Effect of yeast cultures supplementation on live weight change, rumen fermentation, ciliate protozoa population, microbial hydrolytic enzymes status and slaughtering performance of growing lamb

Yeast cultures are being exploited as a substitute of antibiotics in animal feeding to promote gut health and performance. This experiment assessed the effect of supplementation of the live yeast cultures on live weight change, rumen fermentation, ciliate protozoa population, microbial hydrolytic enzymes status and slaughtering performance of growing lamb during post weaning phase of growth. Sixty weaner lambs were fed ad libitum a composite feed mixture (CFM) for 91 days in five equal groups. The CFM had roughage to concentrate (R:C) ratio of 25:75. In addition to CFM control lambs were supplemented sterilized culture while other lamb groups received either Kluyveromyces marximanus (NRRL3234; KM), Saccharomyces cerevisiae (NCDC42; SC), Saccharomyces uvarum (ATCC9080; SU) or mixed (all tree cultures in 1:1:1 ratio) culture. The yeast cultures contained 1.5–2.0 × 109 cells per ml, which were fed at 1 ml per kg live weight to each lamb of treatment groups. Dry matter intake was similar among control and yeast culture supplemented lambs ranging from 68.4 to 81.2 g/kg W0.75. However, daily gain was higher (p = 0.002) in SC and mixed yeast culture supplemented lambs. Half carcass weight ranged from 14.2 to 15.1 kg and dressing 52.2 to 53.5% were similar among five lamb groups. Similarly, other carcass traits did not change by yeast supplementation. The SU and mixed culture supplementation declined rumen fluid pH and total volatile fatty acid (TVFA) concentration. Individual yeast cultures increased but mixed yeast culture reduced total ciliates protozoa. Individual cultures increased Entodinomorphs while mixed culture reduced its number in rumen ecosystem. The SU culture increased (p = 0.023) Diplodinomorphs population. Proteases activity was 499, 407, 284 and 144 units higher respectively, in mixed, SC, SU and KM culture supplemented lambs. Cellular activity of α-amylase enzyme was lower in SC, KM and mixed yeast culture lambs. Extra cellular activity of β-glucosidase enzyme was similar (p = 0.581), whereas cellular (p = 0.007) and total activity was higher (p = 0.029) in SU culture lambs. The extra cellular and total activity of xylanase was not different but cellular activity was higher (p = 0.042) in KM lambs. The carboxymethyle cellulase activity was similar among the five animal groups. The SC, SU and mixed culture supplementation improved feed intake (p = 0.722) by 8.0, 13.3 and 18.8% and daily gain (p = 0.002) by 26.6, 11.7 and 18.8% respectively in lambs. The SC culture feeding promoted feed intake and growth by 8 and 26.6% respectively showing the suitability of growth promoting microbial feed additive. The SC culture supplementation in rumen ecosystem also facilitated microbial growth and improved activity of short chain polysaccharides degrading micro-organism. Therefore, SC culture can be used as a growth promoting feed additives in meat animal production.