Abstract
ObjectiveThe main objective of this study was to evaluate the effect of different feeding levels of a total mixed ration silage-based diet on feed intake, total tract digestion, enteric methane emissions, and energy partitioning in two beef cattle genotypes.MethodsSix mature bulls (three Thai natives, and three Thai natives - Charolais crossbreeds) were assigned in a replicated 3×3 Latin square design, with cattle breed genotype in separate squares, three periods of 21 days, and three energy feeding above maintenance levels (1.1, 1.5, and 2.0 MEm, where MEm is metabolizable energy requirement for maintenance). Bulls were placed in a metabolic cage equipped with a ventilated head box respiration system to evaluate digestibility, record respiration gases, and determine energy balance.ResultsIncreasing the feeding level had no significant effect on digestibility but drastically reduced the enteric methane emission rate (p<0.05). Increasing the feeding level also significantly increased the energy retention and utilization efficiency (p<0.01). The Thai native cattle had greater enteric methane emission rate, digestibility, and energy utilization efficiency than the Charolais crossbred cattle (p<0.05). The daily metabolizable energy requirement for maintenance in Thai native cattle (388 kJ/kg BW0.75, where BW0.75 is metabolic body weight) was 15% less than that in Charolais crossbred cattle (444 kJ/kg BW0.75).ConclusionOur results suggested that the greater feeding level in zebu beef cattle fed above maintenance levels resulted in improved energy retention and utilization efficiency because of the reduction in enteric methane energy loss. The results also indicated higher efficiency of metabolisable energy utilization for growth and a lower energy requirement for maintenance in Bos indicus than in Bos taurus.
Highlights
Energy loss in ruminant livestock through enteric methane emissions is a problem because of the impact on climate change and owing to the considerable effect on animal productivity
Beef and dairy cattle contribute the most to methane emissions due to their greater body size, energy intake, and population size; they produce 61% of the emissions attributed to all domestic animals [1] and cause a loss of enteric methane energy accounting for 2% to 12% of gross energy (GE) intake
Thai native cattle showed higher values for dry matter (DM) and nutrient digesti bility than Charolais crossbred cattle (p
Summary
Energy loss in ruminant livestock through enteric methane emissions is a problem because of the impact on climate change and owing to the considerable effect on animal productivity. Cattle (Bos taurus [B. taurus] and Bos indicus [B. indicus]), produce significant amounts of methane via anaerobic gut digestion. Beef and dairy cattle contribute the most to methane emissions due to their greater body size, energy intake, and population size; they produce 61% of the emissions attributed to all domestic animals [1] and cause a loss of enteric methane energy accounting for 2% to 12% of gross energy (GE) intake. The use of feeding strategies to reduce enteric methane emissions is a priority in improving animal productivity and environmental sustainability [3]. Zebu cattle (B. indicus; referred to in this report as Thai native cattle) and their crossbreeds with European cattle (B. taurus) provide the main genotypes for beef cattle populations www.ajas.info
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