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Context: Tropical legumes are commonly assumed to share all positive attributes known from temperate legumes such as lucerne. However, increasing evidence exists on the differences between those forages, particularly in terms of their ruminal degradability. Aims: Exploring the 24-h rumen in vitro -fermentation characteristics of tropical legumes, their direct comparison with lucerne, and their interactions with grasses depending on their nutritional quality. Methods: Arachis and stylosanthes (tropical legumes), pennisetum and andropogon (tropical grasses), and lucerne (lucerne_21 and lucerne_35, harvested 21 and 35 days after emergence respectively) were used for the study. On the basis of the nitrogen and neutral detergent fibre (NDF) concentration, arachis and pennisetum were classified as of good quality, while stylosanthes and andropogon as of poor quality. The following four incubation series were performed: first, forages alone were incubated under iso-nitrogenous conditions; second, forages were incubated under iso-nitrogenous conditions with supplemented starch; third, NDF extract of each forage was incubated alone; fourth, NDF extract of tropical grasses and legumes was incubated combined in grass : legume proportions of 33 : 67 and 67 : 33. Key results: When incubated alone, gas production (GP) and total short chain fatty acids were higher for temperate legumes, intermediate for tropical legumes and lowest for tropical grasses. Similar trends were observed for GP when the forages were incubated with starch, but the differences between arachis and lucerne_35 disappeared; short chain fatty acids did not differ among all tropical forages. Moreover, acetate : propionate ratio was highest for tropical legumes, intermediate for temperate legumes, and lowest for tropical grasses. Gas production of NDF extracts was highest for the lucerne samples and lowest for the tropical legumes. Improvements in GP were found when the NDF from the poor-quality grass (andropogon) was combined with the legumes, particularly the good-quality legume (arachis). Conclusions: On the basis of the gas production, tropical legumes appear to have lower degradability than do temperate ones, while also showing a different fermentation pattern. Fibre of tropical legumes is less degradable than that of tropical grasses, but when combining both fibre sources, there seems to be a synergistic effect on degradability. Implications: The current results give important insights on the fermentation characteristics of tropical legumes, helping better understand their role in ruminants' nutrition, while giving inputs towards improving their utilisation. The effects of feeding tropical legumes on the animal responses are strongly dependent on the quality of both the legume and the grass they supplement. We found that tropical legumes are more fermentable than are tropical grasses, but their fibre fraction is less degradable than that of grasses. Synergism occurred between the fibre of grasses and legumes, particularly when a good-quality legume supplemented a grass. These results can help understand and optimise strategies to successfully feed tropical legumes to ruminants. [ABSTRACT FROM AUTHOR]

The aim was to determine the effect of substituting pumpkin seed cake (PSC) or extruded linseed (ELS) for soya bean meal in goats’ diets on milk yield, milk composition and fatty acids profile of milk fat. In total, 28 dairy goats were divided into three groups. They were fed with concentrate mixtures containing soya bean meal (Control; n=9), ELS (n=10) or PSC (n=9) as main protein sources in the trial lasting 75 days. Addition of ELS or PSC did not influence milk yield and milk gross composition in contrast to fatty acid profile compared with Control. Supplementation of ELS resulted in greater branched-chain fatty acids (BCFA) and total n-3 fatty acids compared with Control and PSC (P<0.05). Total n-3 fatty acids were accompanied by increased α-linolenic acid (ALA, C18:3n-3; 0.56 g/100 g fatty acids) and EPA (C20:5n-3; 0.12 g/100 g fatty acids) proportions in milk of the ELS group. In contrast, ELS and PSC resulted in lower linoleic acid (LA, C18:2n-6; 2.10 and 2.28 g/100 g fatty acids, respectively) proportions compared with Control (2.80 g/100 g fatty acids; P<0.05). Abovementioned resulted in lower LA/ALA ratio (3.81 v. 7.44 or 6.92, respectively; P<0.05) with supplementation of ELS compared with Control or PSC. The PSC diet decreased total n-6 fatty acids compared with the Control (2.96 v. 3.54 g/100 g fatty acids, P<0.05). Oleic acid (c9-C18:1), CLA (c9,t11-18:2) and t10-,t11-C18:1 did not differ between treatments (P⩾0.08), although stearic acid (C18:0) increased in ELS diets compared with Control (12.7 v. 10.2 g/100 g fatty acids, P<0.05). Partially substituted soya bean meal with ELS in hay-based diets may increase beneficial n-3 fatty acids and BCFA accompanied by lowering LA/ALA ratio and increased C18:0. Pumpkin seed cake completely substituted soya bean meal in the diet of dairy goats without any decrease in milk production or sharp changes in fatty acid profile that may have a commercial or a human health relevancy. [ABSTRACT FROM PUBLISHER]

Milk fatty acid (MFA) have already been used to model methane (CH4) emissions from dairy cows. However, the data sets used to develop these models covered limited variation in dietary conditions, reducing the robustness of the predictions. In this study, a data set containing 140 observations from nine experiments (41 Holstein cows) was used to develop models predicting CH4 expressed as g/day, g/kg dry matter intake (DMI) and g/kg milk. The data set was divided into a training (n = 112) and a test data set (n = 28) for model development and validation, respectively. A generalized linear mixed model was fitted to the data using the marginal R2 (m) and the Akaike information criterion to evaluate the models. The coefficient of determination of validation (R2 (v)) for different models developed ranged between 0.18 and 0.41. Form the intake-related parameters, only inclusion of total DMI improved the prediction (R2 (v) = 0.58). In addition, in an attempt to further explore the relationships between MFA and CH4 emissions, the data set was split into three categories according to CH4 emissions: LOW (lowest 25% CH4 emissions); HIGH (highest 25% CH4 emissions); and MEDIUM (50% remaining observations). An ANOVA revealed that concentrations of several MFA differed for observations in HIGH compared with observations in LOW. Furthermore, the Gini coefficient was used to describe the MFA distribution for groups of MFA in each CH4 emission category. The relative distribution of the MFA, particularly of the odd- and branched-chain fatty acids and mono-unsaturated fatty acids of observations in category HIGH differed from those in the other categories. Finally, in an attempt to validate the potential of MFA to identify cases of high or low emissions, the observations were re-classified into HIGH, MEDIUM and LOW according to the proportion of each individual MFA. The proportion of observations correctly classified were recorded. This was done for each individual MFA and for the calculated Gini coefficients, finding that a maximum of 67% of observations were correctly classified as HIGH CH4 (trans-12 C18:1) and a maximum of 58% of observations correctly classified as LOW CH4 (cis-9 C17:1). Gini coefficients did not improve this classification. These results suggest that MFA are not yet reliable predictors of specific amounts of CH4 emitted by a cow, while holding a modest potential to differentiate cases of high or low emissions. [ABSTRACT FROM AUTHOR]

Two trials with multiparous dairy cows were conducted. Experiment 1 tested the effects of increasing forage proportion in the diet (500, 600, and 700 g/kg DM) when a mixed sorghum (Sorghum bicolor) and jackbean (Cannavalia ensiformis) silage was used as forage. Experiment 2 studied the substitution of sorghum silage and soybean meal by jackbean silage or fresh cowpea (Vigna unguiculata) forage in the diet. All diets were iso-energetic and iso-proteic. In each experiment, 30 cows were used and separated into three groups. In experiment 1, there were no differences in dry matter intake (DMI), milk yield (MY), or apparent total tract digestibility (aTTd) among the three diets, but milk fat content increased with increasing forage proportion, even though the similar neutral detergent fiber of all diets. Nitrogen use efficiency was highest in the diet containing 600 g forage/kg DM, and some evidence was observed for a better profitability with this forage proportion. In experiment 2, feeding legumes increased DMI despite no effects on aTTd. Milk yield increased in line with DMI, with a larger increase for the fresh cowpea. Nitrogen use efficiency and milk composition were not affected by the diets. The increased MY and lower feed costs increased the economic benefits when feeding legumes, particularly when feeding fresh cowpea. Feeding fresh cowpea or jackbean silage to dairy cows appears to be an alternative to soybean as protein source, ideally at a forage proportions of 600 g/kg DM, without altering milk yield and quality and increasing the farm profitability.