Resumo

POSADA, Sandra L et al. Productive and microeconomic evaluation of commercial sources of bovine somatotropin application in dairy cows. Rev Colom Cienc Pecua [online]. 2008, vol.21, n.1, pp.27-38. ISSN 0120-0690.

This study was proposed with the aim to analyze productive and microeconomic responses of holstein friesian cows that were treated with one of two commercial sources of recombinant bovine somatotropin (BST-r). Thirty cows form 1 to 4 parity and 60 to 180 days in milk (DIM) were evaluated. Daily milk production was recorded; incidence of mastitis and body condition score (BCS) were measured once a month. In addition, open days (OD) were measured in not pregnant cows at the begging of the study. Milk yield variable was analyzed by a completely randomized design with a factorial 2 x 3 x 7 arrangement plus a covariable. Factors considered in the model were: calving (primiparous or multiparous); hormone treatment: group 1, BST-r1 (500 mg) + vitamin E (1665 UI) + lecitine (166.5 mg), group 2, BST-r2 (500 mg), and control group without treatment; and time (application 3 to 9). DIM at the beginning of the study was used as a covariable. Open days (OD) variable was e by a completely randomized design with a 3 x 3 factorial arrangement. Factors considered in the model were parity (2, 3 or 4) and hormone treatment (with the same three levels above mentioned). The BCS variable was analyzed by the non-parametric Kruskal-Wallis method (five times). Hormone treatment or parity did not significantly differ (p> 0.05), although number of application (p<0.01) and DIM at the beginning (p<0.01) did. There was a significant effect of the interaction between hormone treatment and parity on OD variable (p<0.05). Neither BCS nor mastitis incidence showed significantly differences between treatment groups (p> 0.05). To perform the micro economical analysis, a one-year-projected-simulation was performed for each treatment group in order to establish a benefit/cost ratio, where BST-r2 treated group exhibited the best ratio. However, hormone treatment increased OD and induced economic losses in production process.

Palavras-chave : body condition score; mastitis incidence; milk production; open days; relationship benefit/cost.

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