Herbage Utilization Research Articles

Calculating herbage utilization and intake by dairy cows under subtropical conditions using conventional field measurement techniques or the HerbValo method.

This study aimed to evaluate the HerbValo method in comparison to conventional field measurement techniques as a tool for estimating the herbage utilization and dry matter (DM) intake by grazing dairy cows under subtropical conditions. It was carried out during 18 months in a commercial farm of Southern Brazil. The herbage utilization was estimated monthly in two to four randomly selected paddocks (total n = 40) using the rising-plate meter or the double-sampling technique. In parallel, the herbage utilization was estimated by the HerbValo method, which is based on simple descriptions of the herd, supplements, pasture and grazing management. Values of herbage utilization estimated by field techniques were linearly (P < 0.01) related to those estimated by HerbValo, with no effect of pasture type (tropical vs. temperate) on the origin or on the slope of the regression (slope = 0.97; origin = -0.1; R2 = 0.81; rsd = 0.17 t DM/ha). At cow × day level, values of herbage intake estimated by field techniques were also linearly related to those estimated by HerbValo (P < 0.01; R2 = 0.82; rsd = 1.30 kg DM/cow/day). A negative linear relationship (P < 0.01) between herbage and supplement intake was obtained for both field (slope = -1.06; R2 = 0.72; rsd = 1.64) and HerbValo (slope = -0.92; R2 = 0.82; rsd = 1.08) approaches. Herbage utilization and intake by a dairy herd in a subtropical grazing-based system can be reliably estimated by the HerbValo method with the advantage of not requiring direct field pasture measurements.

Appropriate livestock grazing alleviates the loss of plant diversity and maintains community resistance in alpine meadows

Alpine meadows constitute one of the major ecosystems on the Qinghai-Tibetan Plateau, with livestock grazing exerting a considerable impact on their biodiversity. However, the degree to which plant diversity influences community stability under different grazing intensities remains unclear in this region. This study conducted controlled grazing experiments across four levels of grazing intensity (no-, low-, medium-, and high-grazing) based on herbage utilization rate to assess the influence of grazing intensities on plant community structure and diversity-stability relationships. We discovered that high-grazing reduced plant diversity and attenuated the temporal stability and resistance of above-ground biomass. No- and low-grazing could alleviate plant biomass loss, with community resistance being optimal under low-grazing. The direct effects of livestock grazing on temporal stability were found to be negligible. Plant characteristics and diversity accounted for a substantial proportion of livestock grazing effects on community resistance (R2 = 0.46), as revealed by piecewise structural equation model analysis. The presence of plant diversity enhances the resistance of alpine meadows against disturbance and accelerates the recovery after grazing. Our results suggest that low-grazing intensity may represent a judicious option for preserving species diversity and community stability on the Qinghai-Tibetan Plateau.

Long-term effects of extensive grazing on pasture productivity

Context In grazed grassland, the per area output of animal-source products usually declines with decreasing stocking rates because of lower herbage utilisation efficiency. Consequently, nutrient export is larger with increased stocking intensity, which should decrease the productivity in the long term. However, little information is available on long-term productivity of extensive grasslands under varied stocking intensities receiving no input. Aims The effect of stocking intensity was investigated in a long-term grazing trial over 16 years of production. We hypothesised that, despite minimal nutrient export under grazing, no reduction in productivity occurs over long-term periods, but expected an interaction between stocking intensity and year. Method The net pasture productivity was determined in terms of animal performance assessed from Fleckvieh cows grazing in a randomised block design with three replicates in three different stocking intensities (moderate, lenient, and very lenient, corresponding to stocking rates of 1.1, 0.7, and 0.5 livestock unit/ha.year respectively), recorded from 2005 to 2020. Metabolisable energy in GJ/ha.year (MEtotal) provided by the pasture and the livestock unit grazing days/ha.year (LUGD, 1LU = 500 kg) were calculated on the basis of liveweight measurements. Key results The interaction of year and treatment significantly affected LUGD (F = 16.85, d.f. = 30, P &lt; 0.0001) and MEtotal (F = 12.81, d.f. = 30, P &lt; 0.0001) and indicated a cyclic trajectory with increases and decreases in performance over the study years. Overall, the moderate stocking intensity led to and maintained significantly higher performance than did very lenient grazing of up to 60% and 55% in LUGD and MEtotal respectively. However, structural equation modelling indicated a negative temporal trend irrespective of stocking intensity. Conclusions On the basis of existing data of herbage quality and botanical composition from the same experiment, this trend was likely to be a result of nutrient redistribution within pastures that probably changed the botanical composition and grass sward productivity in conjunction with drier years towards the end of this study period. Implications This study showed that productivity in low-input grassland under continuous grazing declines over time irrespective of stocking intensity. Productivity decline in all treatments implies tradeoffs for farmers grazing at lower stocking intensities.

Herbage utilisation method affects rumen fluid and milk fatty acid profile in Holstein and Montbéliarde cows

Compared with maize silage- and concentrate-based diets, herbage-based diets were repeatedly shown to favourably influence the milk fatty acid (FA) profile. However, it is unclear how the herbage feeding mode (grazing vs indoor green-feeding) and conservation (fresh herbage vs hay vs silage) modify the milk FA profile. Therefore, the aim of the present experiment was to investigate the effect of different herbage utilisation methods (including herbage feeding mode and herbage conservation method) on the ruminal biohydrogenation of dietary FA and the consequences on the milk FA composition in cows of two breeds (Holstein and Montbéliarde). Concomitant effects of botanical composition and phenological stage of the herbage on milk FA profile were controlled for by harvesting barn-dried hay and silage simultaneously as first cut from the same ryegrass-dominated grassland in a semi-mountainous region. Seven weeks later, the first regrowth of the same plot was used as fresh herbage, either grazed or fed indoor (indoor green-feeding). Twenty-four Montbéliarde and 24 Holstein cows were randomly allocated to four groups of 12 cows balanced by breed, parity, and milk yield. In a free-stall barn, three groups were given ad libitum access to hay, silage, or fresh herbage, respectively. The fourth group was strip-grazing. All cows were supplemented with 3 kg DM/day of the same energy-rich concentrate. After 2 weeks of adaptation to the forage, samples of forage, concentrate, milk, blood, and rumen fluid were collected. Fatty acid composition of forages, rumen fluid, and milk was analysed by gas chromatography. Haymaking reduced total FA content of the herbage, in particular that of linoleic acid (LA) and α-linolenic acid (ALA). Still, rumen fluid lipids of hay-fed cows had the highest proportion of rumenic acid, LA, ALA, and total polyunsaturated fatty acids (PUFAs). Milk fat from hay-fed cows had the highest proportion of LA, and the apparent transfer rates from feed to milk of LA and ALA were higher in hay-fed cows than in silage-fed cows. The proportion of PUFAs was highest in milk fat from grazing and indoor green-fed Montbéliarde cows and lowest in silage-fed cows of both breeds. In conclusion, the herbage utilisation method affects the ruminal biohydrogenation of LA and ALA, whereby herbage drying particularly increases their transfer from herbage to milk.

Nutrient utilization of native herbage and oat forage as feed for Tibetan sheep (Ovis aries)

AbstractSatisfying the animals feed demand from the forage supply by grasslands remains a major challenge in the grassland–livestock ecosystem. To provide an alternative forage sources, this study conducted two feeding trials in the summer of 2015 and 2016 to compare the nutritive value, digestibility and nutrients utilization of native pasture (NH) and oat forage (OT) fed to Tibetan sheep (Ovis aries). Twelve Tibetan sheep with a mean body weight of 39.11 ± 3.66 kg in 2015 and 27.97 ± 2.69 kg in 2016 were use in this study. The experiment was 2 (year: 2015 and 2016) by 2 (forage: NH and OT) factorial. Data on proximate analysis, fiber fraction and nutrients digestibility were collected and analyzed using general linear model. However, the crude protein (CP) and water‐soluble carbohydrates contents in OT were higher (P &lt; .001) than those in NH by 7.81–8.93% and 46.40–47.05%, respectively. In contrast, the neutral detergent fiber (NDF) and acid detergent fiber contents were higher (P &lt; .001) in NH by 14.28–15.78% and 15.62–18.00%, respectively. The dry matter digestibility coefficient in OT (0.82 in 2015 and 0.79 in 2016) was significantly higher than that in NH (0.68 in both years). In addition, the OT diet had higher (P &lt; .001) organic matter, NDF and CP digestibilities. Animals fed OT retained significantly more nitrogen (2.66 g/day in 2015 and 1.93 g/day in 2016) than those fed NH (0.96 g/day in 2015 and 0.42 g/day in 2016). The digestible energy and metabolizable energy were higher (P &lt; .001) in OT than in NH. Our data indicated that Tibetan sheep urinary N excretion increased by 0.726 g with increase of 1 g in the nitrogen intake. Conclusively, the OT had higher nutritive value than NH and could therefore use to satisfy livestock demand and reduce the grazing pressure on grasslands.

Intra and inter-annual climatic conditions have stronger effect than grazing intensity on root growth of permanent grasslands

Understanding how direct and indirect changes in climatic conditions, management, and species composition affect root production and root traits is of prime importance for the delivery of carbon sequestration services of grasslands. This study considers the effects of climatic variability and gradients of herbage utilisation by grazing on root production over the course of two years. The root and leaf traits of the plant communities were determined to detect their capacity to predict above- and below-ground net primary production, ANPP and BNPP, respectively. A long-term field experiment was used to compare the effects of abandonment and low (Ca-) and high (Ca+) grazing intensities (resulting in mean residual plant heights of 15.2 cm and 7.7 cm, respectively) induced by grazing rotations on upland fertile grasslands after 10 years of treatment application. Ingrowth cores and exclusion cages were used to measure, respectively, the root and shoot mass production several times each year and at an annual scale. The root and leaf traits of the communities were measured near the vegetations peak growing season. We observed strong seasonal root production across treatments in both a wet and a dry year, but the response to grazing intensity was hardly observable within growing seasons. In the abandonment treatment, the spring and autumn root growth peaks were delayed by approximately one month compared to the two cattle treatments, possibly due to a late plant canopy green-up induced by lower soil temperatures and an accumulation of litter. The BNPP was slightly lower in the abandonment treatment compared to the cattle treatments only during the dry year, whereas a decline of the ANPP in the abandonment treatment compared to the Ca+ treatment was observed during the wet year. In response to drought, which occurred during the second year, the root-to-shoot biomass ratio was stable in the cattle treatments but declined in the abandonment treatment. The higher allocation to root mass could benefit plant communities under drier conditions. Rotational grazing pressures and climatic condition variabilities had limited effects on root growth seasonality, although drought had stronger effects on the BNPP than on the ANPP. The stability of the root-to-shoot biomass ratio during the dry year evidenced a higher resistance to drought by grazed versus abandoned grassland communities.

Optimization of Profit for Pasture-Based Beef Cattle and Sheep Farming Using Linear Programming: Model Development and Evaluation

A linear programming optimization tool is useful to assist farmers with optimizing resource allocation and profitability. This study developed a linear programming profit optimization model with a silage supplement scenario. Utilizable kilograms of pasture dry matter (kg DM) of the total pasture mass was derived using minimum and maximum pasture mass available for beef cattle and sheep and herbage utilization percentage. Daily metabolizable energy (MJ ME/head) requirements for the various activities of beef cattle and sheep were estimated and then converted to kg DM/head on a bi-monthly basis. Linear programming was employed to identify the optimum carrying capacity of beef cattle and sheep, the most profitable slaughtering ages of beef cattle, the number of prime lambs (sold to meat processing plants), and sold store lambs (sold to other farmers for finishing). Gross farm revenue (GFR) and farm earnings before tax (EBT) per hectare and per stock unit, as well as total farm expenditure (TFE), were calculated and compared to the average value of Taranaki-Manawatu North Island intensive finishing sheep and beef Class 5 farming using Beef and Lamb New Zealand (B+LNZ) data. The modeled farm ran 46% more stock units (a stock unit consumed 550 kg DM/year) than the average value of Class 5 farms. At this stocking rate, 83% of the total feed supplied for each species was consumed, and pasture supplied 95% and 98% of beef cattle and sheep feed demands, respectively. More than 70% of beef cattle were finished before the second winter. This enabled the optimized system to return 53% and 188% higher GFR/ha and EBT/ha, respectively, compared to the average values for a Class 5 farm. This paper did not address risk, such as pasture growth and price fluctuations. To understand this, several additional scenarios could be examined using this model. Further studies to include alternative herbages and crops for feed supply during summer and winter are required to expand the applicability of the model for different sheep and beef cattle farm systems.

Feeding cows with hay, silage, or fresh herbage on pasture or indoors affects sensory properties and chemical composition of milk and cheese

In European countries, silage-free feeding is an ancient tradition and has a particularly positive reputation among consumers. In the present study, we compared grass-based forages from the same plot conserved as hay or silage or fed fresh either on pasture or indoors, and we evaluated the differences in sensory properties of milk and uncooked pressed cheese. All herbage from the first cut of a grassland dominated by perennial ryegrass was harvested on the same day and preserved either as hay or silage. The first regrowth of the same plot was used for strip grazing or green feeding indoors. Balanced by breed, 24 Montbéliarde and 24 Holstein cows were allocated to the 4 treatments. Apart from the forages, the late-lactation cows received 3 kg/d of dry matter from concentrate. After 2 wk of dietary adaptation, the bulk milk of 3 subgroups, each with 4 cows, was collected. Part of the milk was pasteurized, and part was left raw and partly transformed to small-sized Cantal-type cheese ripened for 9 wk. Milk and cheese underwent descriptive sensory analysis by a trained sensory panel, as well as analyses of physicochemical traits. Volatile organic compounds of the cheeses were also analyzed. Raw and pasteurized milk from hay-fed cows had less intense odors of cooked milk, cream, and barnyard than milk from grazing cows, whereby the effect of pasteurization did not differ between herbage utilization methods. Cheeses obtained from cows fed fresh herbage (grazing and indoors) were clearly yellower than cheeses from silage- and hay-fed cows, which coincided with the color intensity perceived by the panelists. Moreover, cheeses from cows fed fresh herbage had more intense barnyard and dry fruit flavors, were perceived as creamier and having less lactic odor, and exhibited more fat exudation than those from cows fed conserved herbage. Only a few differences were observed in milk and cheeses from hay-fed compared with silage-fed cows, and those differences were far less pronounced than those of milk and cheeses from cows fed fresh herbage. In conclusion, the present study did not substantiate assumptions of clear sensory differences of milk and uncooked pressed cheese from hay-fed compared with silage-fed cows. For the first time, this study reports that the global flavor intensity of cheeses from indoor green-fed cows is similar to that of cheeses derived from cows fed conserved forages, whereas cheeses from grazing cows have the greatest global flavor intensity.

Impacts of cutting frequency and position to tree line on herbage accumulation in silvopastoral grassland reveal potential for grassland conservation based on land use and cover information

AbstractIn agricultural grassland, high herbage utilisation efficiency (HEFF), which is the proportion of gross live‐green herbage production that is utilised before entering senescence, is ensured by frequent defoliation. The decision upon which defoliation frequency to apply depends on the farming intensity. Assuming a reduced total herbage accumulation near trees in silvopastoral systems, frequent defoliations with high HEFF become less worthwhile—at least in specific spatial configurations. This makes an extensive management near trees an interesting option because it promotes other grassland‐related ecosystem services such as biodiversity. The present study first analysed the interaction between defoliation frequency and position to trees on the total, dead and live herbage accumulation and the HEFF at two silvopastoral sites with short‐rotation coppices in Germany. In addition, the total grassland–tree interface in Germany was assessed from land use and land cover maps of Germany based on satellite data to approximate the potential of grassland extensification near trees. The total herbage accumulation near trees declined by up to 41% but the HEFF was not affected by the position. Consequently, any intensification is not paid‐off by adequate productivity and herbage quality in terms of HEFF and tree‐related losses in herbage accumulation are expected up to a distance of 4.5–6 m. Applying a 4.5 m border on satellite data, we found that up to 4.4% (approximately 2200 km2) of the total grassland area in Germany is at a tree interface and potentially suitable for extensification. These findings indicate substantial potential for biodiversity conservation in grasslands with low trade‐off for high‐quality yield.

Seed Quality in Forage Crops: Current Status and Gaps in Ethiopia

This paper summarizes forage seed quality attributes, stages to be considered for quality seed production, current status, and gaps of forage seed quality in Ethiopia. Seed quality is one of the main factors affecting crop production potential. Seed quality such as genetic quality, physiological quality, physical quality, and pathological quality should be considered during seed production. The pre-planting stage is the first stage to be considered for the production of good quality seed. The environmental conditions under which the forage crop is grown and the cultural practices used for production can affect seed quality. Several environmental factors such as soil conditions, nutrient deficiency, water stresses, extreme temperatures, and pest infestation may affect seed quality by reducing its viability and vigor by the time the seed reaches physiological maturity. Besides, identification of suitable sites, use of proper seedbed preparation, sowing time, seed rates, and planting methods are also considered to affect quality forage seed production. The post-planting stage such as weeding, pest and disease control, time of harvest, and field inspections at different stages is the second stage to be considered for quality seed production. Determination of seed harvesting stage of some forage species is more complex compared to food crops due to unsynchronized seed maturity and seed shattering problems so that identification of optimum seed harvesting stage for species which have indeterminate growth habit is very important. The post-harvesting stage such as drying, threshing, cleaning, packing, storing, transporting, and marketing is the third most important stage to be considered for quality seed production. Forage plants are cultivated mostly for herbage utilization so that seed production does not virtually exist in the country. The price of small-seeded perennial forage species and their cost of production are very high globally due to low seed yield performance, unsynchronized seed maturity, seed shattering problem, and difficulty in postharvesting and handling processes compared to most annual forage species. Some of the beneficial qualities of forage seeds can be stored for a longer time, relatively free of disease, and not attacked by pests like weevils compared to food crops. Some forage seeds have a problem of seed dormancy but the problem can be solved by mechanical, chemical, and hot water scarification. Generation of different forage seed production technologies which are feasible for different agroecologies are extremely important for higher and quality seed production but the technologies are not yet well known for most forage species.

Sheep and Goats Respond Differently to Feeding Strategies Directed to Improve the Fatty Acid Profile of Milk Fat.

Simple SummarySheep and goat milk, as well as dairy products, are considered good sources of high-quality nutrients, particularly proteins and fats. Many positive effects on human health have been attributed to the consumption of dairy containing specific fatty acids, including some compounds originating from the polyunsaturated FA (PUFA) biohydrogenation operated by rumen microbes. In this bibliographic review, several nutritional strategies able to improve the milk fatty acids (FA) profile, in terms of an increase in the concentration of fatty acids considered beneficial to human health, are presented and discussed, with special attention to the differences between the two species.This bibliographic review presents and discusses the nutritional strategies able to increase the concentration of beneficial fatty acids (FA) in sheep and goat milk, and dairy products, with a particular focus on the polyunsaturated FA (PUFA), and highlights differences between the two species. In fact, by adopting appropriate feeding strategies, it is possible to markedly vary the concentration of fat in milk and improve its FA composition. These strategies are based mostly on the utilization of herbage rich in PUFA, or on the inclusion of vegetable, marine, or essential oils in the diet of lactating animals. Sheep respond more effectively than goats to the utilization of fresh herbage and to nutritional approaches that improve the milk concentration of c9,t11-conjugated linoleic acid (c9,t11-CLA) and α-linolenic acid. Dietary polyphenols can influence milk FA profile, reducing or inhibiting the activity and growth of some strains of rumen microbes involved in the biohydrogenation of PUFA. Although the effectiveness of plant secondary compounds in improving milk FA composition is still controversial, an overall positive effect has been observed on the concentration of PUFA and RA, without marked differences between sheep and goats. On the other hand, the positive effect of dietary polyphenols on the oxidative stability of milk fat appears to be more consistent.

Herbage utilisation efficiency of continuously stocked pastures during periods of restricted pasture growth

ABSTRACTThe aim of this study was to evaluate the defoliation patterns of individual tillers, efficiency of herbage utilisation, and forage production in continuously stocked Brachiaria humidicola cv. Comum swards during periods of the year of restricted pasture growth. The experiment was conducted at the Embrapa, Campo Grande-MS, Brazil, from April to October 2012. Treatments consisted of two grazing management strategies, defined by two ranges of sward height (10–15 and 20–25 cm) managed under continuous and variable stocking rates. The experiment was conducted as a completely randomised block design with three replications. During periods of resource constraints, grazing management strategies based on ‘steady state’ sward heights did not alter defoliation patterns, herbage utilisation efficiency (HUE), and forage production in Brachiaria humidicola swards under a continuous stocking method. A direct implication of our results is that grazing management strategies during the driest and coldest periods of the year in the tropics should be developed based on the conditions most suitable for better promoting faster pasture recovery and a return to production in the following spring; it is unlikely that any grazing management strategy would be successful in increasing herbage production and/or HUE in periods of restricted pasture growth.

The Effect of Herbage Conservation Method on Protein Value and Nitrogen Utilization in Dairy Cows

Ruminant production systems frequently rely on grassland utilization and conservation of herbage as hay or silage. Conservation affects the crude protein (CP) composition and protein value, which is particularly recognized during ensiling. The aim of the current study was to describe the effect of the conservation method on forage protein value and N utilization in dairy cows. Herbage from the same sward was cut and conserved as silage (SI), barn-dried hay (BH), or field-dried hay (FH). Laboratory evaluation indicated differences in CP fractions and ruminal degradability of CP. Conserved forages were fed to six lactating Holstein cows in a replicated 3 × 3 Latin square design, and N balance was assessed. Partitioning of N into milk, feces, and urine was affected only moderately. Lower concentrations of serum, milk, and also urinary urea indicated lower N turnover for FH compared to SI and BH, likely due to lower N intake for FH. However, the use efficiency of feed N for milk N did not differ between the types of forage. Further, high CP concentrations and the unbalanced concentrations of CP and energy in the forages led to excess excretion of N in all treatments and presumably superimposed effects of the conservation method on N utilization.

Mitigation of enteric methane emissions through pasture management in integrated crop-livestock systems: Trade-offs between animal performance and environmental impacts

We evaluated the effect of different grazing intensities by steers on animal performance, herbage intake and CH4 emissions in the stocking period of a soybean-beef cattle integrated system in southern Brazil. Treatments consisted of different grazing intensities, defined by target sward heights (10, 20, 30 and 40 cm) of mixed black-oat (Avena strigosa Schreb.) and Italian ryegrass (Lolium multiflorum Lam.) pastures under continuous stocking. Grazing management affected herbage utilization and, consequently, animal performance and CH4 emission. At the individual level, CH4 emission and animal performance had optimal values when pasture height was managed within a range of 23–30 cm. At the farm level, we found a positive linear effect of grazing intensity on animal live weight gain per hectare and the associated environmental costs of land use. Liveweight gain increased by 90 g ha−1 day−1 and CH4 emissions increased by 500 g CO2eq ha−1 day−1 for each cm of target sward height reduction. Given that most producers graze pastures to very short heights, large-scale adoption of target heights within 23–30 cm in southern Brazil has the potential to achieve 13–14% of the mitigation target for GHG emissions from the whole agricultural sector and 22–25% of the target for enteric fermentation from the livestock sector pledged by the Brazilian Government in the Paris Agreement. We conclude that adequate grazing management is the key strategy to improve animal production and reduce the environmental impact from livestock in ICLS.

Seasonal changes in dry matter yield from Karst pastures as influenced by morphoclimatic features.

Pastures are strongly affected by local environmental variables in terms of their species richness, plant composition and herbage production. A multi-site monitoring study was conducted over three years to investigate the influence of morphoclimatic factors on the seasonal variations in dry matter (DM) yield from Karst pastures. Seven sites located on the Italian and Slovenian Karst regions were investigated that differed in terms of their geological and geomorphological features, as well as their soil types. At each site, the daily DM yield (kg ha-1 d-1) was determined using Corral-Fenlon method which permits to simulate herbage utilization from grazing herds. The morphoclimatic features were also analysed, with the aim to evaluate the link between seasonal DM yield and geomorphological and environmental factors. Generalized non-linear mixed models were built to study the observed seasonal variations in DM yield, using day of the year (DOY), growing degree days (GDD), and cumulative rainfall. Furthermore, environmental descriptors were included in the model in order to evaluate their effects on DM yield. The seasonal variations in yield showed two growing periods (spring and late summer), which were described by Gaussian curves. For the spring growing period, the model improved when the interaction between soil granulometry and growing degree days corresponding to the curve peak was taken into account. This confirms the influence of soil type and air temperature on pasture yield. For the late summer growing period, the interaction between the sand classes and the number of rainy days from the beginning of the period to the peak of the curve improved the model. The curve parameters of our models are correlated with environmental descriptors depending on the lithology and particle size of soils. The results are essential for the optimization of pasture management and avoiding degradation due to over- or under-grazing.

Understanding factors associated with the grazing efficiency of perennial ryegrass varieties

Abstract Herbage utilisation is of primary importance to grassland farmers due to its strong association with profit, yet it is not assessed in routine grass evaluations. On commercial grassland farms, grazing efficiency of varieties is believed to influence their level of herbage utilisation. To understand grazing efficiency the interaction between plant and animal is critical; mechanically simulated grazing protocols are limited in the information they provide. The objective of this paper was to further understand the grazing efficiency of perennial ryegrass varieties by identifying grazing traits which can be used as selection criteria by breeders striving to develop varieties with improved herbage utilisation. Fifty-five perennial ryegrass varieties, both diploid and tetraploid with intermediate and late heading dates, were sown in plots (3 m × 7 m; 21 m2) following a randomised block design with three replicates per variety. Swards were rotationally grazed by lactating dairy cows during the 2015 and 2016 grazing seasons. Sward structural, morphological, and chemical characteristics were measured and related to grazing efficiency, as measured by post-grazing sward height. These data were analysed using the PROC MIXED procedure to test the fixed effects of traits and the GLM procedure to test their relationships with grazing efficiency. Varieties were shown to differ in their level of grazing efficiency (p

Effect of daily herbage allowance restriction on pasture characteristics and milk production by grazing dairy cows in spring

The cumulative effects of daily herbage allowance (DHA) restriction on pasture characteristics and the sustainability of pasture-based dairy systems were evaluated. Sixty-four dairy cows were randomly assigned to one of two grazing treatments (20 and 30 kg DM cow-1 day-1). Milk yield and pre- and post-grazing herbage mass were recorded for every grazing event. Botanical and chemical compositions of the pasture were evaluated. Low DHA increased the stocking rate by 0.7 cows ha-1 and consequently increased grazing efficiency from 41 to 47%. Daily herbage allowance restriction did not affect pasture characteristics or milk production per cow, but DHA restriction increased milk production per hectare (+27%). The results suggest that restriction on daily herbage allowance ensures a higher level of herbage utilization and milk output per ha than high DHA, without affecting pasture characteristics. Therefore, DHA might be a useful grazing management tool for improving the profitability and sustainability of grazing-based dairy systems.

The effect of grazing intensity on the performance of high‐yielding dairy cows

AbstractThe study evaluated the impact of High, Moderate and Low grazing intensities throughout the grazing season, within a rotational stocking system, on the performance of high‐yielding dairy cows receiving a high level of concentrates. Sixty‐three Holstein‐Friesian dairy cows, 21 at each grazing intensity, were rotationally grazed. Average paddock size, post‐grazing sward heights and seasonal grazing stocking rates within the High, Moderate and Low grazing intensities were 0.143, 0.167 and 0.200 hectares, 5.2, 6.1 and 6.8 cm and 7.8, 6.7 and 5.6 cows ha−1 respectively. Grazing intensity had no effect on milk fat and protein content, end‐of‐study body condition score or end‐of‐study live weight although the latter tended towards significance (p = .057). Average daily milk yield per cow was higher within the Low grazing intensity (33.2 kg day−1) than High grazing intensity (30.5 kg day−1), and average daily fat‐plus‐protein yield was higher for Low and Moderate than High. Milk output per hectare was higher for the High grazing intensity than Low grazing intensity (33,544 and 26,215 kg ha−1 respectively). Grazing intensity had no effect on grazing bite number, blood metabolites or concentrations of milk fatty acids or on sward morphological components, although dead matter increased with time across all grazing intensities. Herbage utilization efficiency (above 1,600 kg DM ha−1) was 52%, 74% and 87% for Low, Moderate and High respectively. It is concluded that high‐producing dairy cows can graze at high levels of utilization when they are receiving high rates of concentrates. Although cow performance will be reduced, milk yield per ha will increase.

Combination of legume-based herbage and total mixed ration (TMR) maintains intake and nutrient utilization of TMR and improves nitrogen utilization of herbage in heifers

Diets combining herbage and total mixed rations (TMR) are increasingly used in temperate regions for feeding ruminants, but little information is available regarding the effects on nutrient intake and digestion of this feeding management in beef cattle. The aim of this study was to determine the effects of combining TMR (10% CP and 13% ADF), and legume-based herbage (14% CP and 27% ADF) on intake, nutrient digestion, ruminal fermentation, microbial N flow and glucose and nitrogen metabolism in heifers. The experiment was a 3×3 Latin square design replicated three times; each period lasted 18 days (10 adaptation days and 8 measurement days). Nine cross-bred (Aberdeen Angus×Hereford) heifers (214±18 kg) fitted with permanent rumen catheters and housed in individual metabolic cages were assigned to one of three treatments: 24 h access to TMR (T), 24 h access to herbage (H) or combined diets with 18 h access to TMR and 6 h access to herbage (T+H). Data were evaluated using a mixed model. Animals fed T+H (TMR 71% and herbage 29%) diets tended to have a higher dry matter intake as a proportion of their BW than animals fed T. The T+H diet did not change ruminal fermentation (pH, N–NH3 and volatile fatty acids) or the N metabolism relative to the T diet, but increased the glucagon concentration and altered glucose metabolism. Conversely, animals fed T+H had increased purine derivatives excretion, increased N use efficiency for microbial protein synthesis and decreased plasma urea and urinary N excretion relative to animals fed H diet. The use of combined diets led to consumption of nutrients similar to a TMR diet, without reducing nutrient use and could improve N utilization compared with the herbage-only diet.

Effect of ewe prolificacy potential and stocking rate on primiparous flock performance

The objective of this study was to investigate the effect of ewe prolificacy potential (PP; predicted number of lambs born/ewe/year) as dictated by sire breed type, stocking rate (SR; ewes/ha), and their interaction on animal performance in a primiparous flock. The study had a 2×3 factorial design, consisting of two PP levels and three SR incorporating 360 primiparous ewes, comprising of two ewe genotypes (180 medium prolificacy potential (MP – Suffolk crossbred ewes) and 180 high prolificacy potential (HP – Belclare crossbred ewes)). Stocking rates were low (LSR; 10ewes/ha), medium (MSR; 12ewes/ha), and high (HSR: 14ewes/ha). There were 60 ewes per treatment and each treatment was assigned to an individual farmlet of five paddocks for the duration of the study. There was no PP by SR interactions observed for ewe body weight (BW) and body condition score (BCS; P>0.05). Medium prolificacy potential ewes had a higher BW and BCS at initial mating, pregnancy scanning, 6 weeks post-lambing and weaning (P<0.001). At lambing and second mating ewe BCS did not differ by PP (P>0.05). Lambs born to HP ewes achieved a lower average daily gain (ADG) up to 6 weeks of age, but a higher ADG from 10 to 14 weeks of age compared to MP lambs (P<0.01). Post-weaning, and lifetime lamb ADG, carcass traits (weight, conformation, fat score), and days to slaughter (DTS) did not differ by PP. Low SR ewes had a higher BW than ewes at the MSR and HSR, which did not differ from each other at second mating (P<0.001). Lower lamb ADG was recorded at the MSR and HSR pre- and post-weaning (P<0.01) compared to LSR, with MSR and HSR lambs subsequently requiring longer to reach slaughter (P<0.001). Total herbage utilisation was highest at the HSR and lowest at the LSR (with the MSR not differing from either; P>0.05), above the post-grazing sward height of 4.0cm pre-weaning and 3.5cm post-weaning (P<0.05). Carcass output per hectare increased as both PP and SR increased (P<0.001). In summary, Primiparous flock performance was significantly reduced as SR increased from 10ewes/ha to 12ewes/ha and 14ewes/ha, with no further decrease in performance from 12 to 14ewes/ha. Increased carcass output per hectare is achievable through the use of greater PP and SR levels within a temperate grass-based lamb production system.