Abstract
ObjectiveThe main objective of this study was to determine the effect of different diets for early-weaned (EW) calves on rumen development, and how this affects fat deposition in the longissimus dorsi of adult Korean Hanwoo beef cattle.MethodsThree EW groups were established (each n = 12) in which two- week-old Hanwoo calves were fed for ten weeks with milk replacer+concentrate (T1), milk replacer+concentrate+ roughage (T2), or milk replacer+concentrate+30% starch (T3); a control group (n = 12) was weaned as normal. At six months, 5 calves of each group were slaughtered and their organs were assessed and rumen papillae growth rates were measured. The remaining calves (n = 7 in each group) were raised to 20 months for further analysis.ResultsTwenty-month-old EW calves had a higher body weight (BW), backfat thickness (BF), longissimus dorsi muscle area (LMA) and intramuscular fat (IMF) than the control (p<0.05). Organ growth, rumen histology, and gene expression patterns in the 6-month-old calves were positively related to the development of marbling in the loin, as assessed by ultrasound analysis (p<0.05). In the group fed the starch-enriched diet (T3), higher BW, BF, LMA, and IMF were present. The IMF beef quality score of 20-month-old cattle was 1+ for the T2 and T3 diets and 1 for the T1 diet (p<0.05).ConclusionPapillae development was significantly greater in calves fed on high-concentrate diets and this may have resulted in the improved beef quality in the EW dietary groups compared to the control.
Highlights
Weaning of calves using a high energy diet can induce early postnatal metabolic imprinting and offers a possible means for improving carcass yield and beef quality
Our results indicate that hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) regulates efficient energy spending in response to enhanced levels of volatile fatty acids (VFAs) and long-chain fatty acids as a consequence of the introduction of a starch rich concentrate feed into the rumen
We predict this increase in ruminal propionate concentration in calves at early stages corresponds to the increased backfat thickness (BF), longissimus dorsi muscle area (LMA), and intramuscular fat (IMF) score in the body, and influences body weight (BW) gain in the EW-high energy concentrate feed groups in later growing and fattening stages
Summary
Weaning of calves using a high energy diet can induce early postnatal metabolic imprinting and offers a possible means for improving carcass yield and beef quality. Schoonmaker et al [3] reported that an ad libitum high-concentrate feed improved intramuscular fat (IMF) deposition in early-weaned (EW) steers during the growing stage; fat deposition rates were lower when they were fed the same diet in the finishing period. The utilization of starter diets for young calves at an early age is the best approach for improving both rumen papillae development and subsequent performance to attain a favorable growth rate [5]. An alternative strategy to a high energy diet is to wean the calves early and to feed them a high concentrate diet for a defined period to stimulate rumen development with rich VFAs before calves are switched to growing stage diets. The study sought to estimate the effects on Korean Hanwoo steers of a post-early weaning calf management system on growth performance and carcass characteristics
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