Effects of Dietary Energy on Growth Performance, Rumen Fermentation and Bacterial Community, and Meat Quality of Holstein-Friesians Bulls Slaughtered at Different Ages

Abstract

The objective of this study was to evaluate the effects of dietary energy levels on growth performance, rumen fermentation and bacterial community, and meat quality of Holstein-Friesians bulls slaughtered at different ages. Thirty-six Holstein-Friesians bulls (17 months of age) were divided into a 3 × 3 factorial experiment with three energy levels (LE, ME and HE; metabolizable energy is 10.12, 10.90 and 11.68 MJ/kg, respectively) of diets, and three slaughter ages (20, 23 and 26 months). Results indicated that bulls fed with ME and HE diets had higher dry matter intake, average daily gain, and dressing percentage at 23 or 26 months of age. The ME and HE diets also reduced bacterial diversity, altered relative abundances of bacteria and produced lower concentrations of acetate, but higher butyrate and valerate concentrations in rumen fluid. Increasing in dietary energy and slaughter age increased the intramuscular fat (IMF) and water holding capacity. In summary, Holstein-Friesians bulls fed with ME and HE diets, slaughtered at 23 and 26 months of age could be a good choice to produce beef with high IMF. Slaughter age may have less influence than dietary energy in altering fermentation by increasing amylolytic bacteria and decreasing cellulolytic bacteria, and thus, further affecting meat quality.

Effects of dietary energy on antioxidant capacity, glucose–lipid metabolism and meat fatty acid profile of Holstein bulls at different ages

“…In this study, at the age of 20 months, bulls in the LE group had higher IGF1 expressions than those in the ME and HE groups; at the age of 26 months, bull in the LE group had lower IGF1 expressions than those in the ME group. Consistent with those results, we previously observed that the average daily gains were similar at the age of 20 months, whereas increased at the age of 23 and 26 months (Wang, Li et al., 2019). Serum cholesterol is a predictor of energy balance status in cattle (Kim & Lee, 2003).…”

“…The bulls were randomly allocated into three diet treatments, and diets were designed according to the nutrient requirements of beef cattle (NRC, 2016) to achieve metabolizable energy contents of 10.12 (low energy, LE), 10.90 (medium energy, ME) and 11.68 (high energy, HE) MJ/kg. Bulls were individually fed the total mixed rations at 07:00 and 16:30, and the dry matter intake was reported in our previous research (Wang, Li et al., 2019). The dietary ingredients and nutrient composition are shown in Table 1.…”

“…Consequently, the regulation of liver metabolic pathways may affect fatty acids composition of ruminant products. We previously reported that Holstein bulls fed diet with the metabolizable energy at 10.90 MJ/kg and slaughtered at the age of 26 months or Holstein bulls fed diet with the metabolizable energy at 11.68 MJ/kg and slaughtered at the age of 23 or 26 months have higher growth and slaughter performance, and higher IMF content (Wang, Li et al., 2019), but the metabolism and beef fatty acid are still unknown. Therefore, this experiment was to evaluate the antioxidant capacity and glucose–lipid metabolism and beef fatty acid profiles of Holstein bulls.…”

Effects of Dietary Protein Levels on Growth Performance, Carcass Traits, Serum Metabolites, and Meat Composition of Tibetan Sheep during the Cold Season on the Qinghai-Tibetan Plateau

“…Previous studies have indicated that dietary nutrients play a pivotal role in regulating the meat composition of livestock. For instance, increased dietary energy increased the content of intramuscular fat of Holstein-Friesians bulls [42]. Moreover, dietary supplementation with sea buckthorn pomace increased the crude fat content of lambs, but had no significant influence on other nutrient contents [43].…”

Chopping Roughage Length Improved Rumen Development of Weaned Calves as Revealed by Rumen Fermentation and Bacterial Community

“…In this study, the decreasing length of roughage increased the abundance of Pyramidobacter , suggesting that chopping roughage length is beneficial to the health of weaned calves. In addition, our results showed that decreasing the length of roughage increased the abundances of genera Papillibacter and Eubacterium_hallii_group , whose abundances affect butyrate production in the rumen [ 45 , 46 , 47 ], indicating that chopping roughage altered the rumen bacterial community and promoted the development of the rumen.…”