Australian Journal of Agricultural Research · 2005 · 444 citations · 34 references
AgricultureAnimal SciencesPlant SciencesPlant BiochemistryPlant NutritionRuminant NutritionForage Crop NutritionForage NutritionLegume-grass InteractionsLegume-grass MixturesLivestock NutritionNitrogen NutritionForage Grass NutritionForage Legume NutritionMicrobial Nitrogen TurnoverRed CloverRumen Ammonia UtilizationRyegrass SpeciesTannin Effects On NutritionUrinary Excretion Rate
The study aimed to evaluate how replacing ryegrass with red clover or alfalfa, with or without Acacia mearnsii tannin extract, affects nitrogen metabolism and methane emissions in sheep. Sheep were fed diets where ryegrass was partially replaced by red clover or alfalfa, with or without 41 g kg⁻¹ Acacia mearnsii extract, and nitrogen excretion and methane production were measured in respiration chambers. Tannin supplementation lowered ruminal ammonia, urinary nitrogen, and methane by about 13 % without altering body nitrogen or energy retention, while legume replacement had no benefit and ryegrass–alfalfa reduced nitrogen and energy utilization and ryegrass–red clover increased methane.
The objective of this experiment was to assess the effects of a partial replacement of ryegrass (Lolium perenne) by red clover (Trifolium pratense) or alfalfa (Medicago sativa) supplemented with 0 or 41 g Acacia mearnsii extract (containing 0.615 g/g condensed tannins)/kg dietary dry matter on nitrogen turnover and methane release by sheep, using the respiration chamber technique. Across all variables, there was no significant interaction between basal diet and tannin supplementation. The partial replacement of the grass by the legumes remained without effect on the amounts of nitrogen excreted through faeces or urine. Nitrogen and energy utilisation was lower (P < 0.05) with ryegrass–alfalfa than with ryegrass alone, and methane release (kJ/MJ gross energy intake) was higher (P < 0.05) with ryegrass–red clover than with ryegrass alone. Tannin supplementation decreased (P < 0.05) ruminal ammonia concentration and urinary nitrogen excretion without affecting body nitrogen and energy retention, and reduced (P < 0.001) methane release by 13% on average. The results suggest that supplemented Acacia mearnsii tannins can be useful in mitigating methane and potential gaseous nitrogen emissions, whereas a replacement of grass by legumes obviously shows no advantage in this respect.
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Thomas H Terrill, Angela Rowan, G. B. Douglas et al. · Journal of the Science of Food and Agriculture · 1992 · 777 citations