Desempenho e desenvolvimento ruminal de bezerros em sistema de desaleitamento precoce recebendo aditivos alternativos aos antibióticos / Performance and rumen development of calves under early weaning program receiving alternative additives to replace antibiotics

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

Two studies were conducted to evaluate alternative additives to replace antibiotics on dairy calves production under early-weaning program. On the first trial, the addition of mannanoligosaccharides (MOS) in the diet of dairy calves on performance and plasma parameters indicative of rumen development, as well as the route of administration, milk replacer or starter feed, were evaluated. Twenty-four male Holstein calves were utilized in a completely randomized design. Calves were distributed in the following treatments: 1) control; 2) mannanoligosaccharides (4 g / d Bio-Mos®, Alltech Biotech.) via starter feed; 3) mannanoligosaccharides ( 4 g / d Bio-Mos®, Alltech Biotech.) delivered via milk replacer. The animals were housed in individual hutches, with free access to water, and received 4L / d liquid diet, split into 2 meals, until weaning at six weeks, and starter feed ad libitum. Fecal scores were evaluated daily. Weekly calves were weighted and growth measurements and blood samples for glucose, urea-N and -hidroxibutyrate (BHBA) were taken until the eighth week of age, when the experimental period ended. There was no significant (P>0.05) effect of treatment or treatment x age interaction for intake, weight gain or body growth. However, there was an age significant effect for all evaluated parameters (P <0.0001). The fecal score was not affected by treatments; however, animals fed MOS via milk replacer presented averages numerically smaller in the first two weeks of life, showing a lower incidence of diarrhea. No significant effects (P>0.05) of treatment or the interaction treatment x age were also observed for plasma concentration of glucose, urea-N or BHBA. However a significant age effect was observed for plasma parameters, with increasing concentrations for urea-N and BHBA, suggesting adequate rumen development. On the second trial, the inclusion of humic substances in the starter and its effects on performance and rumen development were evaluated. Twenty Holstein male calves were used in a completely randomized block design and distributed in two treatments according to inclusion of humic substances in the concentrate starter: 1) Control; 2) Humic substances (Nutrihume®). Nutritional management and evaluated parameters were the same as described for the first trial. However, calves were weaned at the eighth week of age and slaughtered for rumen development evaluation. There were significant effect (P>0.05) for treatment or the interaction treatment x age for concentrate intake, weight gain or growth measurements. Fecal scores were also not affected (P>0.05) by the inclusion of humic substances, even though calves presented frequently high fecal scores, indicating high incidence of diarrhea. There were no significant effects (P>0.05) of humic substances inclusion on the rumen morphometrics measures and papillae number, height or width. On the conditions of these studies, the alternative additives presented no beneficial effects on performance, rumen development or general health of milk-fed dairy calves.

ASSUNTO(S)

additives alimentação animal desmama precoce humus. calves bezerros acids early weaning húmus Ácidos suplementos concentrados para animais. antibióticos antibiotics animal nutrition

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