Effect of Climate Change on Strategy of Forage Feeding in Cattle Farms under Dry Continental Conditions

Abstract

This chapter presents the expected climate scenario in corn-producing areas and suggests alternative strategies for producing resilient forage for dairy cattle in dry continental climate zones. The consideration of irrigating corn for silage production arises due to the alterations in climate. However, it is anticipated that different crop rotations will suffice to sustain the forage supply on intensive dairy farms without requiring additional water resources in the dry season, including drought-resistant crops, early-cut whole-crop cereals, and intense annual ryegrass alongside corn and sorghum. Crop management and crop rotation strategies adapted to local and weather conditions are critical to maintaining milk production. Due to the high digestibility, digestible NDF, and undigestible NDF of the early cut, intensively growing grass silages, rye silage (harvested at the boot stage or earlier), triticale, barley, and wheat silage (harvested at boot-early heading stage) could increase dairy cows’ dry matter intake and milk production under heat-stress conditions. As a result, cattle feed will contain more ingredients than it does today to cope with climate change in cattle feeding.

1. Introduction

An increase in average temperature during the growing season typically results in plants using more energy for respiration to sustain themselves and less for growth. An increase in average temperature of 1°C can reduce major food and cash crop species yields by 5–10 percent [1]. Extremely high temperatures of over 30°C can cause permanent physical damage to plants, and if they exceed 37°C, even seeds can be damaged during storage. The high temperatures can adversely affect photosynthesis, respiration, water relations, and membrane stability, and alter hormone levels and primary and secondary metabolite levels in the plant [2]. Due to climate change, the frequency of periods when temperatures rise above critical thresholds for corn, rice, and wheat is projected to increase worldwide [3]. The general projection is that with climate change, areas that already receive high rainfall will receive even more rainfall while dry areas will become drier [4]. As precipitation patterns become more erratic/unpredictable, farmers may no longer be able to rely on their knowledge of the typical temporal patterns of climatic variables. Changes in planting seasons and weather patterns make it difficult for farmers to plan and manage production.

The extent of climate change can already be measured in the dry continental region of Central Europe through the example of corn silage. The whole plant corn yield range was found to be 17.0–33.5 tons per ha for Hungary during the last decades between 2012 and 2022 [5]. Silage yields exceeded 30 tons per ha in only 5 of the 11 years. Extremely low yields were observed in 2012 and 2022 (19.3 tons per ha and 17.0 tons per ha, respectively). Starch content ranged between 207 and 360 g/kg DM (2012–2022). The whole corn plant was harvested in 2022 with the lowest starch content (207 ± 111 g/kg DM) after a sweltering and dry summer [5]. Corn silage is a common ingredient of dairy rations in most areas of the World. Climate change has increased the frequency and intensity of heat waves in dry continental areas; therefore, the safety yield and quality of corn silage are likely compromised in extensive lands in the future. Consequently, it would be important to consider how crop production and feeding strategies can be adapted to this change in the long term, considering the nutrient requirements of dairy cattle.

Winter cereals are growing during a period of potentially higher rainfall, bypassing periods of heat stress and drought (autumn sowing-early spring harvest), so can be grown with less risk than corn. Therefore, the winter cereals can be part of the climate change strategy. Additionally, the corn-whole crop rye, corn-whole crop triticale, brown midrib (BMR) sorghum-whole crop triticale, or BMR sorghum-intensive high sugar grass double cropping are new crop rotation systems to prevent yield losses due to climate change (drought and heat stress).

Silage can be made from winter whole-crop cereals, but it has a dual function as a cover crop, protecting the soil. There has been a growing interest in seeding winter cereals after corn silage harvest as cover and silage crops. This is due to the recognition by farmers and farm advisors that fall and spring ground coverage is important for erosion control after corn silage harvest. It is also due to the potential of overwintering cereals to retain end-of-season nitrogen, the need for a growing crop to improve the nutrient use efficiency of fall-applied manure, and the addition of carbon to soils through roots and crop residue [6, 7]. Winter crops prevent erosion and give good weed suppression. The rye accumulates much greater biomass than oats in the autumn, providing better winter cover to reduce runoff, erosion, and P loss potential. Rye also has a very strong positive impact on reducing nitrate leaching in the soil profile, as nitrate concentrations at 50 cm depth were extremely low according to experimental results [8].

Double cropping can provide economic and environmental advantages to dairy farmers. Winter cereals harvested early can offer a substantial quantity of extra, nourishing forage while minimally impacting the production of corn silage. Winter cereals, such as rye cultivated as dual crops in corn silage rotations, possess the capacity to enhance on-farm forage production while also offering numerous environmental, economic, and nutritional advantages to dairy farms [9].

The objective of this chapter is to present the projected climate conditions in regions where corn is grown and propose different approaches to develop a robust forage foundation for dairy cattle. We focus on field crops which could be an option for completing the forage sources of countries located in areas with a dry continental climate.

2. The current and future climate situation in dry continental areas

Agricultural production strongly depends on climate conditions. Changes in the mean temperature and precipitation, as well as weather and climate extremes, are already influencing crop yields and livestock productivity in many European regions. A projected increase in the number of extreme weather and climate events throughout Europe is expected to further increase the risk of crop losses and impose risks on livestock production. The impacts of climate change on agriculture vary across Europe. While increases in the length of the growing seasons can improve the suitability for growing crops in northern Europe, the negative effects of climate change will lead to yield losses across Europe, mostly in southern Europe. Elements of climate change affect livestock systems through direct impacts on animal physiology, behaviour production, and welfare and indirectly through water availability [10] and the quantity and quality of forage and feed crops [11, 12].

Animal production based on the use of grain crops may be less sensitive to climate change compared to ruminants that rely on conserved forage (hay and silage) and grazing.

The Intergovernmental Panel on Climate Change (IPCC) has consistently highlighted the significance of anthropogenic influences on the climate system, leading to alterations in temperature and precipitation patterns. The elevated concentrations of greenhouse gases induced by human activity, especially with the highest radiation forces, have played an unequivocal role in modifying the previously quasi-balanced atmospheric processes. Understanding these changes on a seasonal basis is crucial for comprehending the full scope of the impact on ecosystems, agriculture, and society.

The global mean temperature in the last 40 years was significantly warmer than in the second half of the nineteenth century. The global surface temperature was +0.99°C higher between 2001 and 2020 and + 1.09°C higher between 2011 and 2020 than it was between 1850 and 1900. The change over land is more pronounced (+1.59°C) than over the ocean (+0.88°C) [13]. Seasonal differences in Europe are also observed (Figure 1). In summer, the most considerable temperature change happened mostly in the lower latitudes, in the Mediterranean subregion, particularly in the surroundings of the Pirenes, Southern France, North Italy, and the Western parts of the Carpathian basin. The spatial distribution of temperature changes is the reverse in winter. The warming trend becomes more significant as latitude increases with a maximum of above 2°C in the East European Plain and the middle regions of Scandinavia.

Figure 1.

Observed linear trends in mean temperature [°C] and relative precipitation change [%] between 1950 and 2016 in summer and winter (modified, based on Christensen et al. [14]).

Precipitation is the most volatile meteorological element, so analysing its trend variability is also quite difficult. However, the spatial and temporal changes indicate a more uniform pattern. The observed linear trends show a definite reduction in summer in the western basin of the Mediterranean Sea, especially over Spain and along the French and North African coasts. A less significant, but noticeable reduction has emerged in subregions in the whole of Europe. In winter, the spatial distribution of precipitation reduction is similar to those in summer, however with more remarkable changes in the eastern or southeastern parts of Europe, like the Carpathian basin, the Balkan Peninsula down to Greece, or regions around the Black Sea. Furthermore, in summer, the days of heavy rains and storms have increased and will likely further rise in the future, causing severe damage to the natural and built environment. In contrast, the northern parts of Europe can face some increase in the precipitation amount, especially in winter. The mutual effect of the increasing trends in the temperature and precipitation amount indicates a shift in the precipitation type from snow to rain during winters. Consequently, this process reduces the extension of snow-covered areas in winter, which affects the amount of water in the soils and, thereby, the speed and rate of the onset of droughts in spring or summer.

According to the updated Köppen-Geiger climate classification (Figure 2), there are currently large areas in the eastern half of North America and China with similar climate conditions as in Western and Central Europe (Cfa, Cfb, Dfa, Dfb). Higher latitude areas such as Scandinavia and areas with similar climate conditions (Dfc) are experiencing benefits from climate change.

Figure 2.

Updated Köppen-Geiger climate classification by Kottek et al. [15]. Western and Central Europe are located in the Cfb, while Eastern Europe falls in the Dfb climate classification.

Given the anticipated increase in frequency, intensity, and duration of drought periods in the future, it is important to investigate historical and projected patterns of soil moisture availability. The trends in water deficit for grain corn during the growing season between 1995 and 2015 show that the largest contiguous areas most affected by water scarcity are Poland, Spain, Italy, Greece, and the east part of the Carpathian basin (Figure 3). The results of the future projections (2015–2045) based on two different climate models (HadGEM2, MIROC) agree that the crop water deficit will extend to an even larger area; moreover, extreme water shortage is projected to the expanded areas ranging east-west from Slovenia to Bulgaria and north-south from Slovenia through the Western Balkans to Greece.

Figure 3.

Crop water demand for grain corn in the growing season based on observations between 1995 and 2015 (above), and future projections based on HadGEM2 and MIROC between 2015 and 2045.

3. Reducing heat stress for dairy cows

The performance, welfare, and health of cattle are significantly influenced by climatic and meteorological factors. Dairy cows with high genetic potential and intensive metabolism are particularly sensitive to high ambient temperatures. The harmful effects of high ambient temperature in production conditions are enhanced by high humidity and insufficient airflow. If the temperature-humidity index (THI) is above 72, cows are heat-stressed, which means the cows have more heat than they can get rid of. Feed intake usually decreases and, as a result, milk yield also decreases [16, 17]. The effect of heat stress is immediate, 1 day of heat stress results in an average production loss of 1.5–2 litres per cow per day (5–10% of the daily milk yield). Genetic selection specifically aimed at increasing milk production parameters caused a decrease in the heat tolerance of cows. Recently, significant efforts have been made to identify specific genes associated with tolerance and sensitivity to thermal stress [18]. Significant advances in the environmental management of dairy cattle include improved housing and cooling systems (shading, water spraying, ventilation, and combined with fans, sprinklers, and humidification systems). In dairy cattle, part of the milk production lost during heat stress (35–50%) can potentially be restored by nutritional treatment [19]. First, the availability and temperature of drinking water may be a key tool in promoting dry matter intake (DMI) and reducing heat stress. Feed supplements can assist in improving the functionality of the rumen in cows experiencing heat stress [20, 21, 22, 23]. Diets aimed at reducing metabolic heat gain can also contribute to enhancing feed intake and overall performance.

Energy intake is typically the primary dietary constraint for lactating dairy cows in the summer months. One commonly employed method to enhance the energy density of a diet is by decreasing the amount of forage and increasing the proportion of concentrates in the ration. However, this practice should be conducted with care, as this type of diet can be associated with a lower rumen pH. Acute and sub-acute rumen acidosis is often increased under heat-stress conditions and indirectly enhances the risk of developing negative side effects of an unhealthy rumen environment (i.e., laminitis, milk fat depression). Digestion characteristics of neutral detergent fibre (NDF) influence feeding and rumination behaviour, dry matter intake, and efficiency of milk component output [24]. Highly digestible forages can pass through the rumen at a faster rate, which in turn stimulates dry matter intake (DMI) while simultaneously decreasing the heat increment. This process ultimately assists in thermoregulation. Therefore, a rising NDF ruminal degradability not only positively impacts nutrient digestibility, but also influences feed intake and milk production. The correlation between the digestibility of forage NDF and the performance of dairy cows is widely recognised. An increase of one percentage unit in NDF digestibility leads to an additional daily intake of 0.18 kg of dry matter and a daily production of 0.25 kg of 4% fat-corrected milk [25].

When dairy cows are fed high-quality forage, they tend to produce more milk and milk components, experience fewer metabolic disorders, have healthier feet, and live longer. As a result, feeding less grain and focusing on providing quality forage can lead to a higher economic return, specifically in terms of income over feed cost [26]. The various types of whole-crop cereals are excellent sources of fermented forage for ruminants: High NDF digestibility is associated with more fast-pool NDF, less slow-pool NDF, and less undegradable NDF. During the summer months, it is possible to customise the feeding schedule by considering these factors and the NDF characteristics of forage to improve DMI efficiency, especially when animals are experiencing heat stress. Therefore, early-cut whole-crop silage as a high-quality forage type may play a role in alleviating the heat stress of dairy cows in continental areas even under climate change.

4. Possibilities for stabilisation of forage bank in dry continental regions

Climate change increased the number of heat stress days during summer in dry continental Europe. Future changes in temperature, precipitation, and atmospheric CO₂ concentration are expected to carry along an increased risk of mycotoxin contamination of cereals. Recent quantitative estimates have shown that, as a consequence of global warming, increased contamination of cereals with deoxynivalenol (DON) and aflatoxin B1 is expected in certain regions of Europe. Aflatoxins and DON are among the most critical mycotoxins affecting milk production and quality [27, 28]. Difficulties can therefore be expected in the corn silage-based diet of dairy herds; therefore, renaissance of winter whole-crop cereals cut in the early stage of maturity (in boot) is obvious in dry areas. Whole-crop cereals include wheat (Triticum aestivum), barley (Hordeum vulgare), oat (Avena sativa), rye (Secale cereale), and triticale (x Triticosecale) can be harvested as a forage source (silage or haylage) for ruminants, but widely used in many countries in various forms, including pasture, hay, or grain [29]. Small-grain cereals offer many advantages over forage sources, particularly alfalfa (Medicago sativa). They can be grown in a wide range of climatic and soil conditions. Winter cereals are also more drought and cold-resistant than alfalfa [30].

These crops were grown primarily for their grains in the past, but nowadays there are different targets in ruminant nutrition. The soft dough stage was the recommended maturity for ensiling for most small grain cereals as an alternative to corn (Zea mays), especially in areas with too short or too cool growing seasons for silage corn [31]. Recently, in continental regions whole-crop cereals are recommended to harvest at the flag-leaf or early-boot stage for high nutrient quality as a forage supply of high milking dairy cows in intensive systems [32, 33, 34, 35, 36].

Nutrient content and fibre digestibility (48 h in vitro digestibility of amylase treated ash corrected neutral detergent fibre, aNDFomd48) of different ensiled forages in Hungary (2013–2018) are shown in Table 1 [36]. Digestible NDF (dNDF) and NDFD can be used to help us better determine forage quality. The dNDF is an actual nutrient that can be analysed in a lab, whereas NDFD is calculated as the percentage of NDF that is dNDF. Forage with a very high NDFD, but low NDF will not supply much dNDF and other sources of dNDF may be needed in the diet. The NDFD 48 (in vitro NDF digestibility, 48-hour incubation) values of the early dough stage were lower compared to the boot stage. These results confirm the importance of the whole crop cereal silages (harvested in boot stage) in the diet fed in the summertime to maintain the dry matter intake. We can conclude that early cut, intensive growing grass silages (Lolium multiflorum, Festulolium var.), whole crop rye silage (harvested in boot stage or earlier), triticale-, barley-, and wheat silage (harvested in boot-early heading stage) may reduce the DMI drops during the summer in cattle according to the high neutral detergent fibre digestibility (NDFD 48), high digestible NDF (dNDF 48), and low unavailable NDF (uNDF 240) results. In the context of cattle feeding in dry continental regions of Europe, we may refer to these forages as ‘heat stress forages’. Because of the above-mentioned factors, there is an increasing global interest in the production and use of early-cut whole-crop cereal silages in the dairy cow diet, especially during the summer season.

	n1	DM2	CP3	TS4	aNDFom5	ADF6	ADL7	aNDFomd 488	daNDF omd 489	uNDF 24010
		g/kg	g/kg DM	g/kg DM	g/kg DM	g/kg DM	g/kg DM	%NDF	g/kg DM	%NDF
Alfalfa silage/haylage (medium quality)
	1811	408	193	—	426	327	62	40.5	171	48.9
Grass silage/haylage (intensive growing on arable: Lolium multiflorum, Festulolium var.)
	462	343	141	—	502	305	26	65.1	323	24.2
Rye silage (in boot-early heading)
	789	294	136	—	554	330	27	66.2	363	19.3
Triticale silage
in boot-heading	24	316	106	—	579	348	28	59.4	341	19.3
early dough stage	59	362	81	124	516	320	34	47.4	249	28.1
Barley silage
in boot-heading	17	318	132	—	552	329	30	60.4	332	19.3
early dough	59	337	93	134	494	289	31	47.9	232	29.8
Wheat silage
in boot-heading	10	293	118	—	571	337	34	57.9	322	19.3
early dough	32	365	92	122	499	301	34	46.6	237	26.3

Table 1.

Nutrient composition, fibre degradability, degradable, and undegradable NDF content of different ensiled forages in Hungary between 2013 and 2018 [36].

¹

Number of samples.

²

Dry matter.

³

Crude protein.

⁴

Total starch.

⁵

Amylase-treated ash-corrected NDF.

⁶

Acid detergent fibre.

⁷

Acid detergent lignin.

⁸

Degradability of amylase-treated ash-corrected NDF, 48-hour in vitro incubation.

⁹

Degradable aNDFom, 48-hour in vitro incubation, organic matter digestibility in vitro 48-hour incubation.

¹⁰

Undegradable NDF, 240-hour in vitro incubation.

4.1 Early-cut whole-crop winter rye

Winter rye is an excellent forage crop when seeded after early-fall harvested crops. It is ready for harvest in Central Europe in mid-April, which provides great opportunities for double-crop options, and can also fill the gap in years when forage supplies are short [32, 37].

The average yield of early-cut whole-crop rye was 3.63 tons of DM per ha over 3 years in New York State, USA (Table 2). Most cereal rye trials (70%) yielded between 2.5 and 5 t DM per ha [9]. The average yield of early-cut whole crop triticale was 4.88 tons of DM per ha [33].

Forage	Year	Number of fields	Average; t DM/ha	Min; t DM/ha	Max; t DM/ha	Standard deviation
Rye	2012	1	5.38
	2013	7	3.65	2.24	5.35	1.23
	2014	11	3.47	1.64	5.40	1.16
	All	19	3.63	2.22	5.38	1.19

Table 2.

The nutrient content of rye harvested between 2012 and 2014 in New York State [33].

The BBCH (Biologische Bundesanstalt, Bundessortenamt und Chemical Industry) scale is the main system in cereals, based on developmental phases––the principal growth stages. Orosz et al. [37] have found that the effect of three different phenological stages (boot stage: BBCH 49–51, heading: BBCH 57–58; early flowering: BBCH 61–62, respectively) was significant on DM yield of the whole-crop rye cut in very early stage (April-May 2013: 5.0–8.6 tons of DM per ha). Growth stages had a seven-times higher effect on variation of DM yield, than varieties (BBCH 49–51: 5.0–6.2 tons per ha, BBCH 57–58: 6.9–8.2 tons per ha, BBCH 61–62: 8.6–9.5 tons per ha). Therefore, cutting time is critical. Winter rye is faster growing and earlier maturing in the spring than the other winter cereals, including wheat, barley, and triticale. Rye matures rapidly at the flag-leaf, boot, and early-heading stages, with significant reductions in forage quality. This can create the challenge of a very narrow harvest window (the timeframe in which rye can be harvested), particularly if there are rain delays [32]. There can be a very large range in forage quality with only a few days difference in harvest. Quality, palatability, and thus consumption reduce very quickly at the heading stage. The delayed harvest had a significant detrimental effect on nutrient content: The crude protein content at the boot stage (BBCH 49–51: 191–215 g per kg DM) reduced with maturation (BBCH 61–62:114–137 g per kg DM, P ≤ 0.01). The NDF digestibility (aNDFomD 48) declined also with maturation (BBCH 49–51: 60–65% NDF, BBCH 57–58: 51–56% NDF, BBCH 61–62: 44–50% NDF, P ≤ 0.05). The NDF rumen degradability decreased by 8–16% during 7 days and 18–32% during 14 days after the boot stage (P < 0.05) in whole crop rye silage. It can be concluded that nutrition value and digestibility drop very quickly at the heading stage of winter rye, so the optimum harvest window is very narrow. The authors concluded that the harvest window was less than 7 days in the boot stage.

According to the results of a country-wide survey in Hungary [36], the rumen degradable NDF content in corn silage was 209 g/kg DM in 2018 (n = 370). While the rye silage cut at the boot-heading stage contained 363 g/kg DM degradable NDF (2013–2018, n = 789). The degradable NDF content of the whole-crop winter rye cut at the boot-heading stage was higher by approximately 40–50% as compared to the corn silage; therefore, the early-cut whole-crop rye can be denoted as an important source of rumen degradable fibre for the high-lactating dairy cows, especially during the summer heat stress period in dry continental Europe.

Based on the experimental results we can conclude that early-cut whole-crop rye silage harvested in the boot stage (in April), in dry continental areas of Central Europe may be an alternative additional forage besides the corn silage for high-performing dairy cows.

4.2 Early cut, whole-crop winter triticale

Triticale has become more commonly used in dairy cropping strategies in recent years, in part due to the double cropping option with corn or sorghum, and environmental aspects such as the desire to capture nutrients from land-applied manure or to provide winter ground cover that improves land stewardship.

There are new triticale varieties that show promise, as they are multifunctional crops: that triticale can be harvested in the boot stage for high-producing dairy cows, or in the early-milk or dough stage for growing/beef cattle and the grain yield can also be a good commodity (for laying hens, other poultry, sheep, pigs, and cattle). This increases resilience and adaptability to environmental conditions in the face of climate change.

Furthermore, they have a much wider harvest window compared to the forage rye, so a bit more convenient to harvest because it can be harvested later and ages more slowly than rye. Mowing after early rye can open the window further, reducing the risk from weather. Finally, different triticale varieties can be cut 5–10 days later in early spring than forage rye. A week difference can be significant in terms of temperature. We are more likely to achieve successful wilting and ensiling of triticale when compared to rye, especially in regions with a longer growing season.

Experimental data confirmed that the triticale varieties can produce similar or even higher DM yields (Table 3) at the end of April (5.94–5.96 tons DM per ha) and in early May (7.67–7.88 tons DM per ha) as whole crop rye in the similar growth stage (BBCH 45–50, in boot) under normal growing conditions [35]. Yields of forage triticale harvested in New York State (USA) are in Table 4 [33].

Variety	BBCH		Date	Mean
R	45	Before heading: 5–6 cm head in boot	17 April 2016	3.52^aA
	49	Before heading: 7–9 cm head in boot	21 April 2016	5.32^aB
T1	41	Before heading: 3–4 cm head in boot	21 April 2016	5.04^A
	45	Before heading: 5–6 cm head in boot	27 April 2016	5.96^bB
	50	Before heading: 6–10 cm head in boot	06 May 2016	7.88^bC
T2	41	Before heading: 3–4 cm head in boot	21 April 2016	4.79^A
	45	Before heading: 5–6 cm head in boot	27 April 2016	5.94^bB
	50	Before heading: 6–10 cm head in boot	06 May 2016	7.67^bC

Table 3.

Dry matter yield of rye var.

^a–cValues with different letters within the BBCH 45 or 49/50 category differ statistically compared to the rye (P ≤ 0.05).

^A–CValues with different capital letters within a variety differ statistically–effect of the phenological stage (P ≤ 0.05).

Ryefood (R), triticale var. Hungaro (T1), triticale var. Dimenzio (T2) according to the different sampling dates [35].

Forage	Year	Number of fields	Average DM/ha	Min.; t DM/ha	Max.; t DM/ha	Standard deviation
Triticale	2012	13	5.13	1.95	10.44	2.551
	2013	28	4.82	2.46	6.76	1.23
	2014	3	4.35	3.34	5.35	1.01
	All	44	4.88	2.37	7.75	1.68

Table 4.

The nutrient content of triticale harvested between 2013 and 2014 in New York State (USA), sown after corn harvest and harvested in May [33].

Orosz et al. [35] found significantly higher (P ≤ 0.05) dry matter yield with similar NDFD 48 values (Table 5) for the triticale varieties (BBCH 50) 2 weeks later than the rye variety at the stage of the same growth stage (BBCH 49). It can be concluded that there is a wider ‘harvest window’ of triticale, a longer time for harvest compared to the whole crop rye. Moreover, the optimal period of triticale harvest is later by 1–2 weeks compared to rye, when there are more favourable weather conditions for wilting.

Cereal		Rye	Triticale 1		Triticale 2
BBCH code		49	45	50	45	50
Sampling time		21 April 2016	27 April 2016	06 May 2016	27 April 2016	06 May 2016
Dry matter	g/kg	157^a	146^aA	147^aA	169^bA	160^bA
Crude protein	g/kg DM	193^b	257^cA	196^bB	159^aA	150^aA
Crude fibre	g/kg DM	252^b	223^aA	247^bB	231^aA	255^bB
NDF	g/kg DM	545^a	540^aA	570^c	532^aA	556^bB
ADF	g/kg DM	274^b	243^aA	270^bB	245^aA	271^bB
ADL	g/kg DM	20.3^a	21.3^aA	24.7^bB	20.3^aA	23.0^bB
NDFD 481	%NDF	68.2^a	76.5^b	69.6^aB	76.7^bA	70.0^aB
dNDF 482	g/kg DM	372^a	413^c	396^bB	408^cA	389^aB
OMD3	%	76.4^a	80.5^b	75.3^aB	80.0^bA	75.3^aB

Table 5.

Nutrient content and in vivo digestibility of rye var.

¹

In vitro NDF digestibility, 48 hours incubation expressed as a percent of NDF. NDFD = dNDF/NDF * 100.

²

Digestible NDF measured from an in vitro NDF digestion for 48 hours.

³

in vitro digestibility of organic matter.

^a–cValues with different letters within a row differ statistically compared to the rye (P < 0.05).

^A–CValues with different capital letters within a variety differ statistically––effect of the phenological stage (P < 0.05).

Ryefood (R), triticale var. Hungaro (T1), triticale var. Dimenzio (T2) according to the different sampling dates in fresh forage [35].

Two triticale varieties (Table 5) had high NDF digestibility at the early growth stage (BBCH 45, 5–6 cm in boot: NDFD 48 76.5 and 76.7%, respectively). Nine days later there was a significant decrease in fibre digestibility (BBCH 50, 6–10 cm in boot: NDFD 48 69.6 and 70.0%, respectively). Crude protein content dropped, while the NDF, ADF, and ADL content lifted during 10 days [35]. Triticale silage harvested at an early stage (BBCH 45–50) can be an excellent forage for high-yielding dairy herds, while triticale harvested at a later stage (BBCH higher than 50) can be more suitable for beef cattle and dairy heifers.

Consequently, triticale varieties can be additional alternative forages in very early cut systems alongside the rye, but mowing can be executed (1–2 weeks later), under better weather harvesting conditions for wilting [35]. The area can be utilised in the season after triticale has been removed, as there is still time to sow corn, sorghum, and sudangrass.

4.3 Early-cut high-sugar grass (grown on arable in an intensive system)

Italian ryegrass (Lolium multiflorum Lam., var. italicum) evolved in the Mediterranean region, and northern Italy, its cultivation as forage for livestock dates back as far as the twelfth century [38]. Preserved Italian ryegrass is frequently used as forage for dairy cows and is known for their high energy value and highly digestible fibre [39]. Plant breeders have developed annual and perennial ryegrass cultivars with an elevated concentration of water-soluble carbohydrates (WSC) relative to conventional cultivars [40]. The new generation of intensive or sweet grasses, the so-called silage grasses, are gaining ground in arable crops. Nowadays, in addition to Italian ryegrass, the less water-intensive Festulolium, a successful cross between fescue and ryegrass, and hybrid ryegrass are also popular in the dry continental region.

This breeding has focussed on increasing the accumulation of high molecular weight storage sugars (i.e. fructans), particularly in leaf blades rather than sheath bases [41]. Research proposed that perennial ryegrass with a high WSC may improve the balance and synchrony of the nitrogen and energy supply to the rumen [42]. Italian ryegrass exhibits a higher sugar content in comparison to other varieties of grass silage provided that it is harvested in the early stages of harvesting. In this regard, Baldinger et al. [38] reported that Italian ryegrass, which is harvested at the second cut, had a significantly higher (71.87%) sugar content than corn silage.

Narasimaluhi et al. [43] reported that the apparent digestibility of DM, NDF, and ADF of Italian ryegrass were 63.6, 57.3, and 64.1%, respectively. According to Orosz [36], ryegrass silage had higher NDFD 48 values (66.2%, P ≤ 0.05) compared to alfalfa silage (40.5%). NDF rumen degradation rate of ryegrass silages has a higher degree at the point of 12, 24, 30, 48, 120, and 240 hours in vitro compared to alfalfa silages, and similar to the rye silage cut in the boot (Table 6). It can be concluded that the intensive ryegrass silage has a significantly (P ≤ 0.05) higher NDF degradation rate compared to alfalfa silage/haylage (at 12, 24, 30, 48, and 120 hours in vitro incubation time). Moreover, the undegradable NDF content was found to be 24.2% NDF in intensive grass silages (n = 462) compared to the alfalfa silage/haylage samples (48.9% NDF, n = 1811).

	Number of samples	NDFD 12	NDFD 24	NDFD 30	NDFD 48	NDFD 120	NDFD 240	uNDF 240
Forage		%NDF	%NDF	%NDF	%NDF	%NDF	%NDF	%NDF
Alfalfa silage/haylage	1811	17.8	28.7	32.6	40.5	47.3	49.6	48.9
Grass silage/haylage	462	29.2	46.8	52.9	65.1	74.8	75.7	24.2
Rye silage; (in boot)	789	28.9	47.1	53.6	66.2	79.3	80.7	19.3
Triticale silage; (in heading)	24	24.3	41.1	47.4	59.4	78.0	80.6	19.3
Triticale silage; (milky-dough stage)	59	16.6	29.1	34.2	47.4	65.6	71.3	28.1

Table 6.

The NDF rumen degradation rate* of different ensiled forages in Hungary (2013–2018) [36].

^*NDFD 12 = NDF degradability at 12 h, NDFD 24 = NDF degradability at 24 h, NDFD 30 = NDF degradability at 30 h, NDFD 48 = NDF degradability at 48 h, NDFD 120 = NDF degradability at 120 h, NDFD 240 = NDF degradability at 240 h, uNDF 240—undegradable NDF, 240-hour in vitro incubation.

According to the NRC [44] and Jacobs et al.’s [45] report, the CP contents of Italian ryegrass silage were 12.8 and 12.5%, respectively, which is higher compared with other grass and cereals, including corn silage. Orosz et al. [36] have found 14.1% DM CP content, as an average between 2013 and 2018 (n = 462) in Hungary (Table 6).

The total-tract NDF digestibility (TTNDFD) measurement aims to assess the NDF digestibility of feed and rations in animals [46, 47]. TTNDFD can be used to compare the fibre utilisation of different feed or fibre sources. Research work at the University of Wisconsin [47] demonstrates the accuracy of TTNDFD for predicting NDF digestion in vivo (in dairy cows). Typical TTNDFD values for corn silage, alfalfa, and grasses are summarised in Table 7 [48]. It can be concluded that NDF in intensive temperate annual or perennial grass silages degrade faster (kd) and potentially at a higher rate (pdNDF) compared to the corn silage and alfalfa silages. TTNDFD in vivo values confirmed a better NDF digestibility of grass silages.

	Sample number	pdNDF1	kdNDF2	TTNDFD3	TTNDFD range
	(Rock River Lab.)	% NDF	%/hours	% NDF	% NDF
Corn silage	7000	75–85	2–3	42	20–60
Alfalfa silage	7000	60–65	4–6	43	30–60
Temperate grass silage	1200	80–90	6	47	20–80

Table 7.

Typical total-tract NDF digestibility (TTNDFD) values of corn silage, alfalfa, or grass [48].

¹

pdNDF = potentially degradable NDF.

²

kdNDF = rate of NDF degradation.

³

TTNDFD = total-tract NDF digestibility.

Replacing one-third of the corn silage and alfalfa mixture with grass silage increased the NDF content of the forage and increased the TTNDFD. Partial replacement of corn silage and alfalfa fibre with more digestible fibre from grasses increased TTNDFD and improved milk fat without reducing milk production [49].

Reports regarding the positive effects on the forage intake of dairy cows are frequent [50, 51] and some researchers even reported better feed efficiency than feeding corn silage [52]. The favourable nutrient digestibility of these grass silages can be attributed to their relatively low lignin content, resulting in a high concentration of energy. Therefore, new grass varieties that produce high yields offer cows a source of fibre that is both easily digestible and structurally beneficial.

Early harvesting grass silages have the potential to mitigate the negative impacts of climate change on dairy cows during the summer season. By extending the growing season beyond the summer period and avoiding the reduction in biomass harvested per hectare through double cropping with sorghum-type forage, these characteristics offer a viable solution.

4.4 Cereal-cereal and cereal-grass mixtures

The mixtures serve to complement the available forage resources within a nation, instead of replacing the current array of varieties. Italian ryegrass-cereal mixtures harvested in April and May can be an alternative feed to corn silage for high-yielding dairy cows in the dry continental areas of Central Europe. The mixtures have been formulated through extensive research and development efforts conducted by Agroteam, an esteemed company based in Italy. These mixtures possess exceptional qualities that set them apart from other feed options available in the European market. The development process relied on the careful selection of specific species and varieties, aligning their breeding periods, and establishing the appropriate germ count and germ ratio. The special mixtures of Italian ryegrass and winter cereals (triticale, oats, barley and wheat; triticale, barley, and wheat; Italian ryegrass and oats; Italian ryegrass, oats, triticale, barley, and wheat) used in practice have several feeding advantages maintain normal rumen environment, improve fibre digestibility and in situ rumen degradation of fibre [53, 54, 55, 56], and fermentation processes in the rumen [9, 54, 57]. Italian ryegrass and winter cereals can be grown together [58, 59]. Legumes are excluded from special blends due to their lower fibre digestibility compared to winter cereals or Italian ryegrass. The wide harvest window results in a good quality of silage in the case of rainy weather or technical failure. The double cropping of winter cereals with Italian ryegrass and corn plants also has environmental and economic advantages, as two different fodder crops are harvested in the same season [33, 60, 61]. The silage mixtures can be successfully used in feed rations for high-production dairy cows due to their highly degradable dry matter and protein content and favourable rumen fermentability [55]. Results and experience suggest that the wider harvesting window, potential yield, multifunctionality, and flexibility make them an excellent element of a new feeding and climate strategy.

4.5 New types of sorghum

Repeated climatic challenges, such as drought, high summer temperatures, or late planting pose significant risks to corn. Therefore, more and more dairy farmers are seeking sorghum varieties suitable for silage-making, which could serve as an alternative to fully or partially replace corn silage for dairy cows. Sorghum’s water usage is much more efficient than corn’s, it can be planted later, it yields significant biomass, and it can still provide acceptable yields even under dry conditions, especially in areas with poor water management [62, 63, 64, 65].

The most important modern hybrid types of sorghum (Sorghum bicolour) are as follows: brown midrib sorghum type (BMR), brachytic dwarf sorghum type, male sterile sorghum type (MS), photoperiod sensitivity sorghum type (PPS), and hybrids of sudangrass and sorghum. A summary of yield, lodging, and quality (DM basis) by sorghum forage types is given in Table 8 [66].

Lodging	DM1	Yield2	CP3	aNDF4	Lignin	Starch	NDFD 485	uNDF om 2406	Milk/ton7
%	%	t/ha	%DM
Brown midrib forage sorghum trait
BMR (34)
2.3	32.5	18.2	7.8	44.9	1.5	8.4	60.8	13.9	3386
Non-BMR (37)
4.1	32.6	18.2	7.9	46.8	2.3	8.7	58.1	15.2	3292.1
Photoperiod response forage sorghum trait
PS (6)
5.6	27.2	17.9	7.2	53.7	1.7	0.3	61.9	16.1	3001
Non-PS (65)
3.0	33.1	17.9	7.9	45.2	2.0	9.3	59.2	14.4	3368
Brachytic dwarf forage sorghum trait
0	32.8	17.9	8.4	45.5	1.8	8.0	60.7	13.9	3337
4.5	32.4	18.2	7.7	46.1	2.0	8.8	58.9	14.8	3337
Corn checks
Corn (3)
0	38.2	11.6	9.9	37.8	2.2	13.8	53.0	13.9	3662

Table 8.

Summary of yield, lodging, and quality (DM basis) by forage type.

¹

Dry matter.

²

Average yield (DM 35%).

³

Crude protein.

⁴

Amylase-treated ash-corrected neutral detergent fibre.

⁵

NDF digestibility, estimated fibre digestibility after the specified length of time (48 hrs.)

⁶

Undigested NDF after fermentation for the specified length of time (240 hrs.) expressed on an organic matter basis to account for the ash.

⁷

A standard dairy cow to project milk produced per ton of forage.

The number in parentheses represents the number of hybrids that make up each sorghum type in 2020 [60].

4.5.1 Brown midrib sorghum type

The digestibility of silage corn in the rumen is much better than that of silage made from traditional sorghum species. Lignin, as an indigestible component of the cell wall, inhibits the breakdown of carbohydrates found in the cell wall. Corn plants contain less lignin than sorghum, and they have more easily digestible starch. Since lignin reduces the digestibility of NDF and the amount of digestible fibre [67], it slows down the ruminal passage, increasing the feeling of fullness in the rumen, which impairs dry matter intake and milk production in traditional and old types of sorghum silage [68]. In the case of BMR-type forages, both the lignin content and the chemical composition of lignin are modified [69, 70, 71]. To date, the most direct and effective way to reduce lignin content and increase the digestibility of forage sorghum is through genetic control of the lignification process via the BMR traits [72]. Both in situ and in vitro digestion studies have shown that BMR forages have better NDF digestion than traditional sorghum species [69, 73].

4.5.2 Brachytic dwarf brown midrib sorghum type

As stated earlier, the BMR trait leads to a decrease in lignin content, thereby enhancing the digestibility of the forage. However, this may increase the risk of stalk lodging. Therefore, in many cases, the BMR genotype has been further developed and combined with the dwarf, but leafy plant phenotype. The term brachytic refers to the dwarf trait, which results in fewer stems and more leaf surface area. The yield was found 18-ton silage per ha in 2020 [66]. The combination of a higher leaf-to-stem ratio and the lower lignin content from BMR brachytic dwarf sorghum results in forage quality similar to or better than corn. The NDFD 48 value (Table 9) was found to be 59–61% [66].

	Risk factor	First year		Second year		Third year
		Spring	Autumn	Spring	Autumn	Spring	Autumn
Traditional crop rotation	+++	Silage cornA	Forage ryeA	Silage cornA	Forage triticaleA	BMR sorghumB	Forage ryeA
Safe version	+	SudangrassC	Forage ryeA	Silage cornA	Forage triticaleA	BMR sorghumB	Forage ryeA
	++	Silage corn (short growing season)A	Italian ryegrass/FestulolliumA	BMR sorghumB	Forage ryeA	Silage cornA	TriticaleA
Irrigated area	+	Italian ryegrassA	Forage ryeA	Silage cornA	Forage ryeA	Silage cornA	Italian ryegrassA
Yield-focus; (for heifers)	++	Silage cornA	Barley with peaC	Forage milletA	Forage triticaleA	SudangrassC	Forage ryeA
	++	BMR sorghumB	Barley with peaC	SudangrassC	Forage ryeA	Silage cornA	Forage triticaleA

Table 9.

Crop rotation examples entirely for forage crop production (Németh and Fazekas, unpublished).

^A

Good for lactating dairy cows.

^B

only for dual-purpose cattle breeds.

^C

only for breeding heifers, fattening, lactating beef cows in winter.

4.5.3 Male sterile sorghum type

According to Kilcer [74, 75, 76], the modern BMR forage sorghum male sterile variety provides excellent quality for silage production in dairy farming. Sorghum cultivation per hectare is cheaper than most corn varieties. The issue is that most sorghum is headed and seed-producing type, which increases the risk of lodging due to ‘look-up head’ and complicates harvesting. The use of MS varieties eliminates the heavy head on the thin stem. Instead of increasing starch content by filling the seeds (glassy and poorly digestible starch), it keeps the components in the cells of leaves and stems. This increases milk production capacity while simultaneously increasing the DM content of the forage. If the sorghum is harvested 1 week after heading, it shows low DM content and moderate energy content compared to corn silage. Seven weeks after heading, the sugar content increases by 500%, and the DM content increases by 18.85% [74]. The nutritive value and milk production capacity of the MS sorghum increases the longer the plant is left after heading. The longer the plant photosynthesizes after heading, the more nutrients accumulate in the stem and leaves. In one trial, non-fibre carbohydrates increased to 71% (corn silage: 82%). Non-starch carbohydrates increased by 185% by the seventh week after heading. NDF decreased by 15%. NDF digestibility, which generally decreases with maturity, decreased by only 8% over the 7 weeks and neutral detergent fibre digestibility (NDFD 30) was 64.1% [75]. During the harvest, kernel cracking should not be used as it increases the risk of effluent formation.

4.5.4 Photoperiod sensitive sorghum type

A photoperiodic sensitivity is a characteristic of sorghum species that allows for the initiation of heading for forage sorghums only when the daytime photoperiod decreases to less than 12.5 hours. The photoperiod-sensitive trait refers to sensitivity to day length, meaning long-day plants require extremely long daylight periods for flowering. This allows for a wider harvest window and ensures favourable fibre digestibility for a longer period. Under limited light conditions, they do not flower and produce seeds, thus maintaining good digestibility for a longer period. Due to this trait, their foliage is generally more abundant than non-long-day species. They can generally be harvested with high sugar content. Neutral detergent fibre digestibility (NDFD 48) was found at 61.9% and lignin content at 1.7% DM (Table 8) in Texas [66].

4.5.5 Hybrids of sudangrass and sorghum

Sorghum-sudangrass hybrids are intermediate in plant size between sorghum and sudangrass. Yield typically falls below that of forage sorghums but is comparable to or slightly greater than sudangrass. Larger stems make drying for hay more difficult than for sudangrasses. Sorghum-sudangrass hybrids are suitable for grazing and can be harvested with a mower-conditioner for silage. When grazed, they yield similar to sudangrass. Nevertheless, sorghum-sudangrass hybrids demonstrate superior yield performance compared to sudangrass upon harvesting the green material. The advantage of sorghum-BMR sudangrass hybrids lies in their favourable fibre digestibility, and they should be grown similarly to sorghum-sudangrass hybrids [77].

4.5.6 The impact of modern forage sorghum silage production on cattle

Feeding trials with lactating dairy cows [68, 78] have demonstrated that BMR-6 forage sorghum (BMR Gene 6 is the highest BMR level, meaning that it contains the lowest level of lignin of any sorghum) resulted in greater DMI, cell wall digestibility, and milk performance when fed to dairy cows compared with non-BMR forage sorghum (Table 10). Moreover, it was found that milk production was similar for cows fed the BMR-6 forage sorghum to a dual-purpose corn hybrid commonly grown in the Midwest, USA.

Reference	Non-BMR sorghum	BMR-6	BMR-18	Corn silage
Oliver et al. [78]	29.2	33.7	31.2	33.3
Aydin et al. [68]; Study 1	20.7	23.7	—	29.0
Aydin et al. [68]; Study 2	31.4	33.8	—	32.4

Table 10.

The effect of BMR, non-BMR sorghum, and corn silage on milk production (4% FCM, kg/day).

Similarly, the meta-analysis of nine different articles published between 1984 and 2015 by Sánchez-Duarte et al. [79] also concluded an overall improvement in lactation performance when cows were fed diets containing BMR forage sorghum silage compared to those based on traditional forage sorghum silage. In the case of diets containing BMR forage sorghum silage, DMI (0.83 kg/day), milk production (1.64 kg/day), milk fat concentration (0.09%), milk fat yield (0.08 kg/day), milk protein yield (0.04 kg/day), and milk sugar yield (0.16 kg/day) improved compared to diets based on traditional forage sorghum silage. Compared to diets containing corn silage, cows fed BMR forage sorghum silage showed increased milk fat concentration (0.10%) and milk sugar yield (0.05 kg/day), but decreased milk protein concentration (0.06%).

In an experiment conducted in the warm weather of Iran, feeding forage sorghum silage (with 2.5% starch and 49.5% NDF) at 25% DM level in the diet did not result in lower milk production when completely substituting corn silage (with 20% starch and 42.3% NDF) at a milk production level of 30 kg/day [79].

BMR-6, BMR-12, and BMR-18 forage sorghum hybrids are known, depending on which allele the mutation occurred [80]. However, the different mutations cause differences in lignin biosynthesis among different hybrids. In a Nebraska experiment [78], cows fed total mixed rations containing BMR-6 or BMR-18 forage sorghum silage (at a ratio of 40% DM, respectively) and corn silage (at a ratio of 40% DM) had similar milk production levels. The apparent digestibility of NDF was similar between diets containing corn silage (54.1%) and those containing BMR-6 forage sorghum silage (54.4%), but lower for BMR-18 forage sorghum silage (47.9%), and the worst for traditional forage sorghum silage-based diets (40.8%). These data confirm that certain BMR forage sorghum hybrids (with starch contents of 14.5 and 16.8%) are capable of achieving similar results to corn silage with lower starch content (19.9%) in 30–35 kg/day milk-producing dairy cows, hence being potentially suitable for (at least) partial substitution of corn silage (Table 10).

4.6 Sudangrass

The brown midrib sudangrass is more palatable and significantly lower in lignin content, making it more digestible than traditional sudangrass. According to research by the University of Wisconsin Extension Forage Team, sudangrass hybrids can yield between 7.5 and 12.5 tons of DM per hectare. In several European countries (The Netherlands, Germany, and Italy), sudangrasses are harvested directly for silage at the heading stage. At this phenological stage, the DM content exceeds 30%, eliminating the need for wilting. Presumably, this technique is chosen to achieve higher yields. However, research indicates that the post-heading phenological stages of sudangrass result in a significant decrease in OM and fibre digestibility and an increase in NDF content. The heading phenological phase is not favourable for feeding silage to dairy cows. Numerous experiments conducted over an extended period have provided evidence that the most favourable period for harvesting dairy cows lies within the timeframe from the appearance of the flag leaf and the beginning of the heading. However, at this time, the DM content ranges from 20 to 27% (depending on the hybrid), which is not yet optimal for direct ensiling. The wilting as a harvesting technique is advisable at this phenological stage. However, it may increase silage ash content.

In a multi-cut forage system (early-stage harvests) 2–3 harvests can be carried out in the same area in the dry continental region. This flexible harvesting technology, combined with excellent fibre digestibility, makes the new sudangrass varieties promising plants for climate change forage strategy.

4.7 Whole crop cereal-legume mixtures (as winter crops)

The cultivation of mixtures of legumes and cereals offers several potential agronomic benefits. Coming from two different plant types, legumes and cereals complement each other in the capture of resources. Differentiation in the size and depth of the root systems of cereals and legumes allows them to utilise water and nutrients from different soil layers, resulting in the compensatory growth and development of plants. Cereal crops growing in the vicinity of legumes benefit from nitrogen assimilated by legume root nodule bacteria. Mixtures are particularly relevant to the exploitation of poorer soils that are unsuitable for the production of either component grown as a sole crop. Yielding of the mixtures is highly dependent on the species and proportions of components. Legumes tend to enhance the quality and nutritional worth of mixed forage owing to their elevated protein concentration. Researchers found that cereal/legumes (fava bean, lupin, and pea) mixed cropping resulted in a significant increase of CP of mixed forage up to 132 g/kg of DM [81].

The University of Wisconsin forage advisor suggests that the timing of harvesting pea barley, pea wheat, and pea triticale mixtures should depend on the production group intended for feeding the silage [82]. The author links the harvesting of the barley-pea mixture to the cereal’s phenological phases. When the barley is in the boot, with only a few heads visible in the field within the mixture (peas not yet flowering) he recommends this excellent digestibility but lower-yielding silage for dairy cows. The starch level is below 2%, yet it possesses a notable amount of energy. At the end of the milky growth stage to the early dough stage of barley (peas in mature flowering with pod initiation), he suggests this high DM and energy-yielding, cost-effective material for heifers and dry cows [82]. Its starch content is over 10%, but its energy content is lower than younger mixes in the boot stage.

Whole crop cereal-legume mixtures harvested at the early waxy growth stage are excellent and cost-effective forages for the growing heifers due to the balanced energy-protein ratio, allowing more corn silage to be used in the dairy herd. Consequently, these silages can be important parts of climate change strategy (Table 11).

	Growth stages of cereals
	In boot	Heading	Milk stage	Dough stage
Change in the proportion of peas in the mixture
Pea ratio	24%	28%	38%	42%
CP (% DM)
Barley	16.6	13.3	10	6.9
Barley and pea	18.6	15.9	14.0	11.3
ADF (% DM)
Barley	35.5	39.8	40.1	45.8
Barley and pea	36.4	38.9	38.7	42.5
NDF (% DM)
Barley	56.1	61.0	58.8	68.8
Barley and pea	53.3	57.5	54.3	60.3

Table 11.

Changes in the nutrient content of grain and mixed silages (2-year average) [83].

	Risk factor	First year			Second year		Third year
		Spring	Summer	Autumn	Spring	Autumn	Spring	Autumn
Emergency situation	+++	Forage oatA	Forage milletA	Forage ryeA	Silage cornA	Forage triticaleA	SudangrassC	Forage triticaleA
	+++	Forage triticaleA spring triticaleA	SudangrassC	Forage triticaleA	BMR sorghumB	Forage ryeA	Silage cornA	Forage triticaleA
	+++	Oats with peasC	Forage milletA	Forage triticaleA	BMR sorghumB	Forage ryeA	Silage cornA	Forage triticaleA

Table 12.

Crop rotation examples in case of failure of crops in spring (Orosz, unpublished).

^A

Good for lactating dairy cows.

^B

only for dual-purpose cattle breeds.

^C

only for breeding heifers, fattening, lactating beef cows in winter.

5. Forage growing and feeding strategy for dry continental regions under climate change situation

As is well known, crop rotation involves growing different crops in a specific order. The following tables list strategies that can be used to effectively implement crop rotation under dry continental conditions (Tables 9 and 11–13). These different crop rotation examples that meet the requirements of high-producing dairy cows may reduce the heat stress of the dairy cattle during the summer in continental regions, and stabilise the farm forage bank providing adequate biomass yield per ha per year, even after a dry and hot vegetation summer period.

	Risk factor	Forages
Forage + grain focus	++	Silage corn	Wheat (grain)		Sudangrass + legumes	Sunflower	Forage rye
	++	Rapeseed	Sudangrass/forage rye	Silage corn	Wheat (grain)		Rapeseed
Forage and seed production	+	Sudangrass	Seed production: clover		Sudangrass + legumes	Oilseed rape	Forage triticale
Forage + grain +seed production	++	Festulolium/Italian ryegrass + clover	Seed production: vetch and wheat		Sudangrass + legumes	Corn(grain)/sunflower	Festulolium/Italian ryegrass + clover

Table 13.

Crop rotation examples for various purposes (Németh and Fazekas, unpublished).

6. Conclusions

Based on the large number of literary data and scientific findings, the following most important conclusions can be drawn.

• Corn silage in the dry continental region faces significant challenges due to extremely low yields, high variability in poor nutritional values, and is therefore considered a high-risk crop. Strategic crop management decisions are essential to enhance the security of the feed bank and improve the quality of silage for dairy cattle. In regions with high levels of risk, it may be deemed necessary to eliminate corn silage from the feed ration; however, there exist alternative measures to ensure the stability of the corn silage supply.

• Winter cereals, which are cultivated from autumn to early spring, have the advantage of growing in a period of increased rainfall while avoiding the adverse effects of heat stress and drought. This presents a promising opportunity to mitigate the risks and minimise yield losses of corn caused by climate change. Therefore, the whole crop winter cereals can be part of a new forage strategy.

• The implementation of novel crop rotation systems, such as corn-whole crop rye, corn-whole crop triticale, brown midrib sorghum-whole crop triticale, or brown midrib sorghum-intensive high sugar grass double cropping, has proven to be highly efficient in mitigating yield reductions caused by climate change in arid continental areas. Moreover, these innovative systems contribute to the stabilisation of the forage bank within dairy farms.

• Intensive cultivation of grass silages (Lolium multiflorum, Festulolium var.), whole crop rye silage (harvested in boot stage or earlier), triticale, barley, and wheat silage (harvested in boot-early heading stage) could potentially enhance the dry matter intake of dairy cows in hot summer conditions due to their high NDF digestibility, digestible NDF content, and low undigestible NDF levels. These forages may be classified as heat-stress forages in the context of cattle feeding in dry continental areas of Europe.

• The degradable NDF content of whole-crop winter cereals harvested at the boot stage exceeds that of corn silage by around 40–50%. Consequently, early-cut whole-crop cereals serve as significant sources of rumen degradable fibre for high-producing dairy cows, particularly in dry continental Europe during the summer heat-stress period.

• In dry continental areas, it is advisable to take into account the utilisation of summer drought-resistant crops such as sorghum and sudangrass. Provided that the NDF digestibility surpasses 60%, these particular forages can be incorporated into the diet of dairy cows.