Morphological development and nutritive value of herbage in five temperate grass species during primary growth: analysis of time dynamics

In a 2‐year field experiment, morphological development and measures of the nutritive value of herbage for livestock during primary growth in Meadow foxtail, Tall oatgrass, Cocksfoot, Perennial ryegrass and Yorkshire fog were investigated. All measured variables were affected significantly by both species and sampling date, and their interaction (P < 0·001), in the period of primary growth. Changes with time in mean stage weight for Meadow foxtail and Cocksfoot were different from the other species due to their indeterminate growth habits. Mean stage weight of Tall oatgrass and Yorkshire fog increased more rapidly than that of Perennial ryegrass with time. Changes in mean stage weight with time were described by linear, parabolic and sigmoid relationships. Crude protein (CP) concentration of herbage was higher for Cocksfoot and Meadow foxtail than for Perennial ryegrass. A parabolic relationship of CP concentration with time was typical for all the species. Concentrations of neutral‐detergent fibre (NDF) and acid‐detergent fibre (ADF) in herbage of the species differed most during the mid‐period of primary growth. Their increases with time showed curvilinear (sigmoid and parabolic) relationships. Perennial ryegrass had lower concentrations of both NDF and ADF in herbage than the other species. Differences between the in vitro dry matter (DM) digestibility among the grasses increased in mid‐ and late periods of primary growth. Perennial ryegrass had higher values for in vitro DM digestibility but the difference from other species was small in the early period of primary growth and from cocksfoot in the late period of primary growth. In vitro DM digestibility showed, in most cases, a sigmoid and, in others, a linear decrease with time. Principal component analysis showed that perennial ryegrass and meadow foxtail were the most distinctive of the species in characteristics relating to morphological development and the nutritive value of herbage to livestock.     

Open pasture,silvopasture and sward herbage maturity effects on nutritive value and fermentation characteristics of cool‐season pasture

In Appalachian USA, silvopasture offers promise of increased farm productivity. A synchronized, temporal understanding of open pasture (OP) and silvopasture (SP) nutritive characteristics is essential for grazing system development. We examined pasture‐type nutritive‐value relationships when herbage was harvested based on morphological maturity rather than calendar date. Neutral detergent fibre and acid detergent fibre (ADF and NDF) content were greater in silvopasture, while organic matter (OM) was lower (P < 0·05). Digestibility of SP herbage dry matter (DM) and OM tended (P = 0·10) to be lower (418 vs. 471 and 437 vs. 491 g kg^?1 respectively). Neutral detergent fibre digestibility was greater (P < 0·05) for OP than SP forage (538 vs. 480 g kg^?1), and ADF tended to be greater (P = 0·10; 551 vs. 501). Open‐pasture forage fermentation effluent exhibited slightly higher microbial richness and Shannon diversity than SP. However, overall community composition of both bacteria and archaea did not differ between pasture types or sampling times. Pasture types show proximate analyses differences generally favourable to OP, although both have similar overall nutritive value. In addition, the SP sward exhibited a 4‐ to 6‐days delay in reaching equivalent maturity. Conversion of farm woodlots to SP would increase overall herbage production and improve pasture management flexibility.     

Influence of solar radiation on the productivity and nutritive value of herbage of cool-season species of an understorey sward in a mature conifer woodland

Silvopastoral systems in the Appalachian region of the USA could increase the carrying capacity of livestock and contribute to a reliable supply of high‐quality herbage. In 2000, 2001 and 2002, the influence of solar radiation [0·20, 0·50 or 0·80 of maximum solar radiation (MSR); treatments 20‐, 50‐ and 80‐MSR respectively] on the productivity and nutritive value of a mixture of sown grasses and legumes established under a mature stand of conifers was investigated. Yields of dry matter (DM), crude protein (CP), total non‐structural carbohydrates (TNC) and total digestible nutrients (TDN) were greater for the 80‐MSR treatment except in 2000 when DM yield did not differ. As a proportion of the sward, introduced species (Dactylis glomerata L., Trifolium repens L., and Lolium perenne L.) increased over time for the MSR‐80 treatment, corresponding with a decrease in the proportion of bare area and of non‐introduced species. CP concentration of herbage was 207 g kg^?1 DM or greater across treatments and years with higher concentrations on the 20‐ and 50‐MSR treatments. Herbage from the 80‐MSR treatment had a greater concentration of TNC than that of the 20‐ and 50‐MSR treatments. Estimated concentration of TDN was similar for all treatments in 2000 and greater for the 80‐MSR treatment than the other two treatments in 2001 and 2002. High CP concentrations in herbage, as a result of appropriate thinning of trees in an Appalachian silvopastoral systems, could be utilized as a protein supplement to herbage with low CP and higher fibre concentrations.     

Effect of humic substances on nutrient uptake by herbage and on production and nutritive value of herbage from sown grass pastures

The effect of humic substances on the nutrient uptake, herbage production and nutritive value of herbage from sown grass pastures was studied in six field experiments. Commercial humic substances were applied in combination with mineral fertilizer or slurry, either as a solution (HF liquid; 8·3 kg humic substances ha⁻¹) or incorporated into the mineral fertilizer (HF incorporated; 3·6 to 6·4 kg humic substances ha⁻¹). A series of cuts, ranging from two to five cuts, was taken during the growing season. The general response in herbage production to application of humic substances was an increase in herbage mass of dry matter (DM) at the first cut although this was only significant in two experiments for the HF incorporated treatment. Total herbage production of DM over the growing season, however, was similar for treatments with or without application of humic substances. The overall effect of HF incorporated and HF liquid on the herbage mass of DM at the first cut across the experiments was calculated using a meta-analysis technique and it was shown that there was a significant proportional increase of 0·14 ( P  <   0·05) with the HF incorporated treatment and a non-significant increase of 0·08 with the HF liquid treatment compared to the control treatment. The nutritive value of the herbage at the first cut was similar across all treatments. In general nitrogen, phosphorus and potassium uptake at the first grass cut was higher after application of humic substances but only in one experiment was this increase statistically significant.     

Nutritive value of acetylated and hydrolysed rapeseed proteins in rats

Acetylated, hydrolysed and unmodified rapeseed proteins were compared to casein for nutritive value as determined by net protein ratio (NPR) and nitrogen apparent digestibility coefficient (ADC). The NPR and nitrogen ADC values of rapeseed proteins did not change significantly (P<0.05) after hydrolysis but decreased significantly (P<0.05) after 30% and 70% acetylation. Acetylation (30%) followed by protein hydrolysis decreased significantly (P<0.05) the NPR value but increased significantly (P<0.05) the nitrogen digestibility compared to the control and unmodified rapeseed proteins. Casein gave the highest value (P<0.05) for NPR and nitrogen ADC. Modification of rapeseed proteins significantly (P<0.05) decreased the nutritive value, and the effect was more pronounced with increasing level of acetylation.     

Proximal sensing of the seasonal variability of pasture nutritive value using multispectral radiometry

The nutritive value of pasture is an important determinant of the performance of grazing livestock. Proximal sensing of in situ pasture is a potential technique for rapid prediction of nutritive value. In this study, multispectral radiometry was used to obtain pasture spectral reflectance during different seasons (autumn, spring and summer) in 2009–2010 from commercial farms throughout New Zealand. The analytical data set (n = 420) was analysed to develop season‐specific and combined models for predicting pasture nutritive‐value parameters. The predicted parameters included crude protein (CP), acid detergent fibre (ADF), neutral detergent fibre (NDF), ash, lignin, lipid, metabolizable energy (ME) and organic matter digestibility (OMD) using a partial least squares regression analysis. The calibration models were tested by internal and external validation. The results suggested that the global models can predict the pasture nutritive value parameters (CP, ADF, NDF, lignin, ME and OMD) with moderate accuracy (0·64 ≤ r² ≤ 0·70) while ash and lipid are poorly predicted (0·33 ≤ r² ≤ 0·40). However, the season‐specific models improved the prediction accuracy, in autumn (0·73 ≤ r² ≤ 0·83) for CP, ADF, NDF and lignin; in spring (0·61 ≤ r² ≤ 0·78) for CP and ash; in summer (0·77 ≤ r² ≤ 0·80) for CP and ash, indicating a seasonal impact on spectral response.     

Nutritive value of protein fractions extracted from soybean,rapeseed and wheat flours in the rat

The nutritive value of various protein fractions was studied. Fractions 2S and 12S from rapeseed, 2S, 7S and 11S from soybean were obtained by dissolution in ammonium sulfate solutions. Albumin-globulin, gluten, glutenin and gliadin fractions from wheat were obtained by dissolution in salted water (albumin-globulin), acetic acid (glutenin) and alcohol (gliadin). Liveweight gains, protein efficiency ratio (PER) and apparent digestibility coefficient (ADC) were used as measures of the nutritive value. The protein fractions had a lower nutritive value than the unfractionated proteins except for the albumin-globulin fraction of wheat which had a nutritive value higher than that of the unfractionated wheat protein. PER obtained with the rapeseed 2S and 12S fractions were 2.49 and 2.21, respectively, as compared to 2.64 for unfractionated rapeseed. With soybean fractions, PER were 0.92 for 2S, — 0.007 for 7S and 1.47 for 11S, as compared to 2.19 for the original protein. The wheat albumin-globulin fraction gave a PER of 2.78, as compared to 1.45 for the unfractionated wheat protein. Gluten, glutenin and gliadin fractions had a lower PER than that of unfractionated wheat protein. ADC of all fractions were higher than those of the original proteins. The difference in liveweight gains and PER observed between protein fractions can be partially explained on the basis of the essential amino acid content.     

Impact of spatial heterogeneity of plant species on herbage productivity,herbage quality and ewe and lamb performance of continuously stocked,perennial ryegrass–white clover swards

The benefits of white clover (Trifolium repens L.) in pastures are widely recognized. However, white clover is perceived as being unreliable due to its typically low content and spatial and temporal variability in mixed (grass‐legume) pastures. One solution to increase the clover proportion and quality of herbage available to grazing animals may be to spatially separate clover from grass within the same field. In a field experiment, perennial ryegrass (Lolium perenne L.) and white clover were sown as a mixture and compared with alternating strips of ryegrass and clover (at 1·5 and 3 m widths), or in adjacent monocultures (strips of 18 m width within a 36‐m‐wide field). Pastures were stocked by ewes and lambs for three 10‐month grazing periods. Over the 3 years of the experiment, spatial separation of grass and clover, compared with a grass–clover mixture, increased clover herbage production, although its proportion in the sward declined through time (0·49–0·54 vs 0·34 in the mixture in the first year, 0·28–0·33 vs 0·15 in the second year and 0·03–0·18 vs 0·01 in the third year). Total herbage production in the growing season in the spatially separated treatments decreased from 11384 kg DM ha^?1 in the first year to 8150 kg DM ha^?1 in the third year. Crude protein concentration of clover and grass components in the 18‐m adjacent monoculture treatment was greater than the mixture treatment for both clover (310 vs 280 g kg^?1 DM) and grass (200 vs 180 g kg^?1 DM). There was no clear benefit in liveweight gain beyond the first year in response to spatially separating grass and clover into monocultures within the same field.     

Nutritive value of rapeseed proteins and fractions supplemented with methionine and tyrosine in rats

Rapeseed protein concentrate (RPC), rapeseed 2S and 12S fractions, a blend of 2S and 12S fractions, retentate (RET) and precipitate (PRE) proteins obtained during rapeseed fractionation were compared to casein for nutritive value as determined by net protein ratio (NPR) and apparent digestibility coefficient (ADC). Tyrosine concentration in rapeseed 2S fraction was the lowest compared to all other protein sources and methionine was the first limiting amino acid. The NPR and ADC of RPC, RET, and fraction 12S did not change significantly (P<0.05) following supplementation with methionine, but for PRE the NPR was decreased significantly (P<0.05). However, the rapeseed 2S fraction supplemented with tyrosine had a NPR significantly (P<0.05) higher than that of RPC and not significant (P<0.05) different from that of casein. The NPR of the 2S and 12S blend was significantly (P<0.05) higher than that of RET and PRE; however, no significant (P<0.05) difference was observed in NPR and ADC of the blend when supplemented with tyrosine. The nutritive value and digestibility of rapeseed 2S fraction were improved by supplementation with tyrosine and by blending with the 12S fraction.     

Identifying suitable temperate grass species and cultural practices for herbage production in the mountain regions of North Vietnam

In North Vietnam, during winter, shortage of herbage constrains the profitability of dairy farming. The first objective of this study was to evaluate the potential of alternative temperate (C₃) forage species, namely common oat ( Avena sativa L.), lop-sided oat ( Avena strigosa Schreb.), Italian ryegrass ( Lolium multiflorum L.) and a commercial forage mixture (Avex), to address the shortage of herbage during winter in the mountain regions of North Vietnam. The second objective was to measure the effects of cultural practices (sowing rate, harvest interval and irrigation level) on yield of dry matter (DM), chemical composition, digestibility of DM and metabolizable energy (ME) concentration of herbage from the best adapted C₃ species previously tested (lop-sided oat). Four experiments were conducted. Oat species proved to be the best adapted species and produced the highest annual yield of herbage (7600 kg DM ha⁻¹) with a high nutritive value. Yields of DM of lop-sided oat were not affected by sowing rate of seed but increased as the length of harvest intervals increased from 30 to 45 and 60 d ( P  <   0·001). Crude protein concentration, digestibility of DM and ME concentration decreased as the harvest interval increased ( P  <   0·01). Irrigation increased the yields of DM of lop-sided oats by 1·3 ( P  <   0·05) but had no effect on the nutritive value of herbage. It is concluded that both common oat and lop-sided oat are suitable species to provide herbage in the winter for the mountain regions of North Vietnam.     

Herbage mass and nutritive value of herbage of extensively managed temperate grasslands along a gradient of shrub encroachment

Semi-natural grasslands often serve as important reserves of biodiversity. In Europe extensive grazing by livestock is considered an appropriate management to conserve biodiversity value and to limit shrub encroachment. However, little is known about the influence of shrubs on agronomic values. A gradient analysis of shrub-invaded temperate grasslands (from shrub-free to pioneer forest) in Germany was carried out to test the hypothesis that herbage mass and variables describing nutritive value of herbage decrease with increasing shrub encroachment. The herbage mass of dry matter (DM), variables describing the nutritive value of herbage, composition of the vegetation and mean of Ellenberg's indicator values were analysed with respect to the extent of shrubs. There was a reduction of herbage mass of DM from 3570 to 210 kg ha⁻¹ with increasing shrub encroachment. Metabolizable energy concentration of herbage ranged from 8·9 to 10·2 MJ kg⁻¹ DM and crude protein concentration from 72 to 171 g kg⁻¹ DM, both measures being positively correlated with shrub occurrence. Increasing shrub occurrence was associated with a decrease in water-soluble carbohydrates concentration (from 151 to 31 g kg⁻¹) and a reduction in the indicator 'forage value'. The results indicate a potentially large agronomic value for shrub-encroached temperate grasslands.     

Effects of livestock breed and grazing intensity on biodiversity and production in grazing systems. 1. Nutritive value of herbage and livestock performance

Reduction of grazing intensity and the use of traditional instead of commercial breeds has frequently been recommended to meet biodiversity and production goals in sustainable grazing systems in Europe. To test the impact of such practices across a range of contrasting grassland types, integrated measurements of foraging behaviour, agronomic production and botanical, structural and invertebrate biodiversity were made over three years on four sites in the UK, Germany, France and Italy. The sites in the UK and Germany were mesotrophic grassland with high productivity and low to moderate initial levels of plant diversity, and were grazed by cattle. The French site was a semi‐natural, species‐rich grassland grazed by cattle. The Italian site contained a wider range in plant diversity, from species‐rich to mesotrophic grassland, and was grazed by sheep. The treatments were: MC, moderate grazing intensity with a commercial breed – this was designed to utilize herbage growth for optimum livestock production; LC, lenient grazing intensity with a commercial breed – this was designed to increase biodiversity by not fully utilizing herbage growth; and LT, lenient grazing intensity with a traditional breed – this was also designed to increase biodiversity. Neither fertilizers nor pesticides were applied. The nutritive value of the herbage and the performance of the livestock were measured. Mean stocking rates were proportionately 0·30–0·40 lower and mean sward heights and herbage mass on offer were 0·30–0·50 higher on the LC and LT treatments compared with the MC treatment. The proportion of live and dead material, and leaves and stems in the herbage, its chemical composition and nutritive value were little affected by the treatments. Individual livestock performance, measured as liveweight gain, showed no consistent response to treatment. In Germany, performance on the MC treatment was slightly lower than on the LC and LT treatments but no such difference was found on the sites in the other countries. Livestock breed did not have a strong effect on livestock performance. In the UK and France the traditional breeds had a lower performance but this was not the case in Germany or Italy. Livestock performance per ha of the LC and LT treatments was up to 0·40 lower than of the MC treatment. It is concluded that biodiversity‐targeted extensive grazing systems have potential to be integrated into intensive livestock production systems because the individual livestock performance reaches a similar level compared to a moderate grazing intensity. Traditional breeds did not have a production advantage over commercial breeds on extensively managed pastures.     

Influence of cutting regime and fertilizer application on the botanical composition,yield and nutritive value of herbage of wet grasslands in Central Europe

The changes in dry matter (DM) yield, botanical composition and nutritive value of herbage to ruminants of two wet grasslands, Arrhenatherum elatius grassland (Experiment 1) and a Molinia caerulea fen meadow (Experiment 2), in which a range of cutting and fertilizer treatments were imposed in 1999, were assessed after 4–7 years of treatment imposition. Both experiments had a split‐plot design with four replicates. In Experiment 1 the three main‐plot cutting treatments were two cuts with a delayed first cut, three cuts and four cuts during the growing season of each year. In Experiment 2 the cutting treatments were two cuts with a traditional harvest time, two cuts with a delayed first cut and three cuts. The four sub‐plot fertilizer treatments were an unfertilized control, application of a phosphorus and potassium (PK) fertilizer, application of a nitrogen (N) and PK fertilizer to the first cut only (N₁PK) and application of PK plus N applied to each of two, three or four cuts (N_c PK). Application of fertilizer influenced yield and botanical composition of herbage more than the cutting treatments while the opposite occurred for nutritive value of the herbage. Application of fertilizer increased the proportion of tall grasses in Experiment 1 and forbs in Experiment 2. The proportion of Equisetum palustre, present only in Experiment 1, was reduced from 0·33 to less than 0·01 by increased cutting frequency together with the NPK fertilizer treatments. In Experiment 1 diversity of vascular plants was negatively affected only by the four‐cuts treatment while on both wet grasslands other cutting and fertilizer application treatments had no effect. Changes in DM yield of herbage caused by the cutting and fertilizer application treatments were similar for both vegetation types with DM yield increased significantly by fertilizer application but only slightly or not reduced by increasing the cutting frequency. Nutritive value of herbage was positively correlated with cutting frequency and was most influenced at the first cut.     

Developing an approach to assess farmer perceptions of the value of pasture assessment technologies

Measurement and monitoring of pasture have been identified as foundations for profitable and sustainable grazing systems. The value that farmers place on pasture assessment in feed management is difficult to ascertain and has seen limited research. The objectives of this study were to test a survey to quantify the perceived value of pasture assessment and identify key criteria for design of pasture assessment technologies. An online survey methodology was piloted with 44 New Zealand farmers to assess perceptions of actual and great grazing management outcomes, good and great pasture assessment, and the value associated with moving from good to great pasture assessment. Results highlighted that many farmers perceive a small potential for improvements in their current pasture performance, whereas industry-level studies suggest that this is not the case. We found limitations with farmers linking better pasture management performance with eventual improvements in milk production. There were anomalies with assessing current and potential improved pasture performance through this type of survey methodology, with many farmers claiming very high levels of current performance, and some rating themselves as performing at more than 100% of potential. This research highlights that pasture assessment technology designers need to be aware of the high expectations of farmers regarding performance, for example measurement accuracy and data timeliness. Over, or under, specification of technology for specific tasks, such as daily allocation of pasture at a herd level, may lead to farmer dissatisfaction around costs of technology, return on investment, and if the technology is fit-for-purpose.     

Effect of defoliation management, based on leaf stage, on perennial ryegrass (Lolium perenne L.), prairie grass (Bromus willdenowii Kunth.) and cocksfoot (Dactylis glomerata L.) under dryland conditions. 2. Nutritive value

A field experiment was undertaken between April 2003 and May 2004 in southern Tasmania, Australia, to quantify and compare changes in the nutritive value of perennial ryegrass (Lolium perenne L.), prairie grass (Bromus willdenowii Kunth.) and cocksfoot (Dactylis glomerata L.) under a defoliation regime based on stage of leaf regrowth. Defoliation interval was based on the time taken for two, three or four leaves per tiller to fully expand. At every defoliation event, samples were collected and analysed for acid‐detergent fibre (ADF), neutral‐detergent fibre (NDF) and total nitrogen (N) concentrations and to estimate metabolizable energy (ME) and digestible dry matter (DDM) concentrations. Amounts of crude protein (CP) and metabolizable energy (MJ) per hectare values were subsequently calculated. There was a significantly lower (P < 0·001) NDF concentration for perennial ryegrass compared with prairie grass and cocksfoot, and a significantly lower (P < 0·001) ADF concentration for cocksfoot compared with prairie grass and perennial ryegrass, regardless of defoliation interval. The CP concentration of cocksfoot was significantly greater (P < 0·001) compared with the CP concentrations of prairie grass and perennial ryegrass. The estimated ME concentrations in cocksfoot were high enough to satisfy the requirements of a lactating dairy cow, with defoliation at or before the four‐leaf stage maintaining ME concentrations between 10·7 and 10·9 MJ kg^?1 DM, and minimizing reproductive plant development. The ME concentrations of prairie grass (10·2–10·4 MJ kg^?1 DM) were significantly lower (P < 0·001) than for cocksfoot (as above) and perennial ryegrass (11·4–11·6 MJ kg^?1 DM) but a higher DM production per hectare resulted in prairie grass providing the greatest amounts of ME ha^?1.     

A comparison of methods to assess the likely on‐farm value for meat production systems of pasture traits and genetic gain through plant breeding using phalaris (Phalaris aquatica L.) as an example

The emphasis plant breeders place on improving seasonal dry‐matter (DM) yield of pasture plants may increase farm profitability through greater supply of DM for livestock in critical seasons. Economic values (EV) for traits can be used to guide plant breeders when selecting ‘top’ pasture plants. Two methods of calculating economic value (EV) for seasonal DM traits were evaluated. These were based on the cost of otherwise acquiring or replacing the unit change in DM (‘replacement cost method’) and the opportunity cost of not having the unit change in DM, based on changes in livestock production either as a change in stocking rate or a change in liveweight gains of growing livestock (‘change in livestock production method’). Using barley replacement cost, the EV of a 1‐kg increase in phalaris DM on Australian sheep and beef farms ranged between AUD0·234 in summer and AUD0·303 in winter. In contrast, the EV for seasonal DM using the change in weaner beef calf liveweight gains ranged between AUD0·256 in summer and AUD0·515 in winter. The change in livestock production method highlighted in this study offers an alternative to the replacement cost method, or more detailed farm system modelling or experimentations designed to estimate pasture EV.