The effect of yeast associated with yeast cell wall on performance and blood parameters from Nellore in stocker grazing phase

The aim of this study was to evaluate the effect of yeast (live yeast concentrate) plus yeast cell wall in the supplement on the intake, average daily gain (ADG), final body weight (BWf) and blood parameters of animals in stocker grazing phase at the rainy season. Sixty Nellore young bulls with initial BW of 349.1 ? 27.4 kg were randomly assigned to four treatments, with three replicates. The animals were distributed in 12 paddocks, with 1.8 hectares each (3 paddocks per treatment), of Brachiaria brizantha cv. Xara?s with a height of 30 cm. Supplement were formulated to fed animals with 0; 2.5 g/an/d of yeast plus 2.5 g/an/d of yeast cell wall; 5 g/an/d of yeast plus 5 g/an/d of yeast cell wall; or 10 g/an/d of yeast plus 10 g/an/d of yeast cell wall. The supplement was constituted of cottonseed meal, citrus pulp, urea, and mineralized salt, containing 22% of crude protein. The animals were group-supplemented at 40 g/100 kg of BW, daily, at 1000 h, in collective feed bunks. Animals were fed for 85 days. The animals were weighed and blood samples were collected in the beginning and in the end of the experiment, after 16 hours of solids and liquids fasting period to evaluate the ADG. Dry matter intake (DMI) was estimated follow the prediction equation: DMI = -2.7878 + 0.08789ABW^0.75 + 5.0487 ADG - 1.6835 ADG². Where DMI = dry matter intake (kg/d); ABW^0.75 = average metabolic body weight; ADG = additional daily gain. Data was analyzed using the GLM procedure of SAS program and the effects of treatments were considered significant at P < 0.05. The inclusion of the yeast plus yeast cell wall in the supplement does not affect the glucose (P = 0.26), insulin (P = 0.91) and NEFA (P = 0.50) concentration. There was no statistical significance (P > 0.05) among the treatments, for ADG, BWf, DMI, and feed efficiency (G:F ratio), with mean values of 0.709 kg/d, 406.7 kg, 7.46 kg/d and 0.096, respectively. The inclusion of the yeast plus yeast cell wall in the supplement did not affect the performance, DMI and blood parameters of Nellore young bulls in pasture at the rainy season.