Evaluation of yeast supplementation in steers housed under suitable temperature-humidity index

The objective of the experiment was to study the effect temperature-humidity index and of live Saccharomyces cerevisiae (NCYC Sc47 E1702) supplementation on protein fractions and haptoglobin serum levels in steers during the growing and finishing phases. Forty Charolais steers were divided into two equal groups: treatment (YS) and control (C). Each animal of the YS group received 5 g/day of yeast supplement added to the same ration of C group. Blood samples were analyzed for total proteins (TP), protein fractions (albumin, alpha(1) -, alpha(2)-, beta(1)-, beta(2) -,gamma- globulins) and haptoglobin (Hp). Ratios between albumin and globulins (A/G) were calculated. Yeast supplementation had a positive effect on TP, albumin, alpha(1,) and beta(1)- globulin levels. Starting from day 1, the differences between C and YS increased during the growing phase and decreased during the finishing phase. Haptoglobin was lower in YS group than C group during growing and finishing phases. These results suggest that the inclusion of Saccharomyces cerevisae in the diet of feedlot steers can modulate protein metabolism as well as haptoglobin concentration when animals are housed in suitable THI conditions.