Levedura seca integral na alimentação de vacas lactantes / Dry yeast for lactating dairy cows

Os efeitos da inclusão de levedura seca de cana-de-açúcar (Saccharomyces cerevisiae) na dieta de vacas lactantes foram avaliados com base no fornecimento de quatro dietas constituídas de diferentes níveis de substituição do farelo de soja pela levedura de cana-de-açúcar (0,00; 0,33; 0,67 e 1,00kg/kg de MS). O delineamento utilizado foi o quadrado latino 4 × 4. Não houve efeito dos tratamentos sobre o consumo de MS, MO, EE, FDNi e NDT, porém ocorreu redução linear no consumo de PB e FDNcp e aumento do consumo de CNF. Diferenças estatísticas não foram verificadas para os coeficientes de digestibilidade aparente da MS, MO, PB, CNF e NDT; no entanto os coeficientes do FDNcp e do EE decresceram linearmente. Não foi observado efeito sobre a produção e eficiência de síntese microbiana, utilização dos componentes nitrogenados e produção e composição do leite. Conclui-se que a levedura seca pode substituir 100% o farelo de soja na alimentação de vacas lactantes.

The effects of the inclusion of sugar cane dry yeast (Saccharomyces cerevisiae) in dairy cows feeding were evaluated based on the provision of four different diets with increasing proportions of sugar cane dry yeast (0.00; 0.33; 0.67 and 1.00kg/kg of DM). The design adopted for this research was the latin square, 4 × 4. It was observed that the levels of yeast inclusion did not affect the intake of DM, OM, EE, NDFi and TDN. However, the CP and NDFcp intake decreased linearly, whereas the NFC intake increased linearly with the increasing levels of yeast. No effect on the digestibility coefficient of DM, OM, CP, NDFcp and NCF was observed. Nevertheless, the EE digestibility coefficient linearly decreased with the yeast inclusion in the experimental diets. There was no treatment effect on the production and efficiency of microbial synthesis, usage of nitrogenous components, as well as milk production and composition. It was concluded that the dried yeast can fully replace the soybean meal in diets of dairy cows.

Evaluating the efficacy of selenium-enriched yeast and sodium selenite on tissue selenium retention and serum glutathione peroxidase activity in grower and finisher swine.

Three experiments conducted with grower-finisher pigs evaluated sodium selenite and a Se-enriched yeast source at various dietary Se levels on Se retention, tissue and serum Se concentrations, and serum glutathione peroxidase (GSH-Px) activity. Experiment 1 was a balance trial conducted in a 2 x 3 factorial arrangement in a randomized complete block (RCB) design in six replicates. Both Se sources were added at .1, .3, or .5 ppm Se. Crossbred barrows (n = 36) averaging 35.9 kg BW were placed in individual metabolism crates and fed their treatment diets, with feces and urine collected for a 7-d test period. Selenium retention increased as dietary Se levels increased, particularly when the Se-enriched yeast was provided, resulting in a Se source x Se level interaction (P < .01). As dietary Se levels increased, urinary Se increased more when pigs were fed sodium selenite, whereas fecal Se increased more when the Se-enriched yeast was fed; both excretion routes resulting in Se level x Se source interaction responses (P < .01). Experiments 2 and 3 were conducted as RCB involving grower (n = 210) and finisher (n = 266) pigs, respectively, and evaluated the two Se sources each at .1, .3, or .5 ppm Se with a non-Se-fortified basal diet serving as a negative control. In Exp. 2, pigs were fed their treatment diets from 22.2 to 60 kg BW in five replicates, whereas in Exp. 3 diets were fed from 65.8 to 105 kg BW in six replicates. Grower pigs fed sodium selenite had serum GSH-Px activity that reached a plateau at .1 ppm Se and .3 ppm when the Se-enriched yeast source was fed, but the interaction response was not significant (P < .15). During the finisher period, serum GSH-Px activity reached a plateau at .1 ppm Se for both Se sources. Serum Se concentrations were lower at .1 ppm Se when the Se-enriched yeast source was fed, resulting in a source x level interaction response for both grower (P < .05) and finisher (P < .01) periods. Loin Se contents were higher in grower and finisher pigs as dietary Se levels increased when the Se-enriched yeast was fed, resulting in a Se source x Se level interaction (P < .01). The results suggest that more Se was retained in muscle tissue when the Se-enriched yeast source was fed, that serum GSH-Px activity reached a plateau at approximately .1 ppm Se, and that sodium selenite may be more biologically available for GSH-Px activity than the Se-enriched yeast source.