- Volume 4 Issue 4
Sixteen Holstein heifer calves were used in an 112-day trial to study the effects of probiotic supplementation on growth performance and rumen metabolism. Calves were divided into four groups of four calves each, with two groups receiving the probiotic supplement and two groups serving as controls. Calves were limited to 1.6 kg dry matter of a corn-barley based grain mix per day. Long-stem bromegrass hay was fed as forage the first 56 days and bromegrass silage the last 56 days of the trial. Probiotic (28 g/d/calf) was fed along with the grain mix twice daily. Data were analyzed for the entire trial and also for the separate hay and silage feeding periods. Total weight gain and average daily gain were not affected (p>.05) by probiotic supplementation. Dry matter intake was lower (p<.05) and feed efficiency (kg feed/kg weight gain) was improved slightly during the hay feeding period for the probiotic-supplemented calves. Wither height gain was greater (p<.05) during the hay period and lower (p<.05) during the silage period for probiotic-supplemented calves. Heart girth gain was improved (p<.07) by probiotic supplementation, particularly during the hay feeding period (p<.05). Total rumen volatile fatty acid (VFA) concentration was higher (p<.05) with the probiotic-supplemented calves. Molar proportions of individual VFA were not affected (p>.05). Rumen ammonia-N and plasma urea-N concentration were lower (p<.05) for probiotic-supplemented calves during the hay feeding period. Total tract nutrient digestibility was not affected (p>.05). Some improvements in animal performance and changes in rumen and blood metabolites were observed when calves were supplemented with probiotic. Effects due to probiotic supplementation were most pronounced during the hay feeding period.