Effects of various weaning times on growth performance, rumen fermentation and microbial population of yellow cattle calves

OBJECTIVE This study was conducted to investigate the effects of weaning times on the growth performance, rumen fermentation and microbial communities of yellow cattle calves. METHODS Eighteen calves were assigned to a conventional management group that was normally weaned (NW, n = 3) or to early weaned (EW) group where calves were weaned when the feed intake of solid feed (starter) reached 500 g (EW500, n = 5), 750 g (EW750, n = 5), or 1,000 g (EW1,000, n = 5). RESULTS Compared with NW, the EW treatments increased average daily gain (p<0.05). The calves in EW750 had a higher (p<0.05) starter intake than those in EW1,000 from wk 9 to the end of the trial. The concentrations of total volatile fatty acids in EW750 were greater than in NW and EW1,000 (p<0.05). The EW treatments decreased the percentage of acetate (p<0.05). The endogenous enzyme activities of the rumen were increased by EW (p<0.05). EW had no effect on the number of total bacteria (p>0.05), but changes in bacterial composition were found. CONCLUSION From the present study, it is inferred that EW is beneficial for rumen fermentation, and weaning when the feed intake of the starter reached 750 g showed much better results.