Resumen

GUARNEROS ALTAMIRANO, Rafael et al. Conditioning around weaning of calves grazing in the dry tropic: effects upon body weight and health condition. Rev. mex. de cienc. pecuarias [online]. 2017, vol.8, n.4, pp.341-351. ISSN 2448-6698.  https://doi.org/10.22319/rmcp.v8i4.4643.

Three experiments (two in the dry season and one in the rainy season) were conducted utilizing 96 Simmental x Zebu calves, with the aim to evaluate the effect of preconditioning during 112 d starting at d 28 preweaning. In four periods of 28 d each, body weight and body condition score of the animals, blood urea nitrogen (BUN) and glucose (SG) in serum, as well as disease frequency in grazing calves were evaluated. Data of BW, cumulative body weight gain (BWG) BUN, and SG were analyzed with ANOVA in a 2 treatments x 2 sex factorial arrangement; morbility was analyzed by Ji square. BW (P=0.552) and BCS (P=0.891) of nursing cows did not vary due to treatments. Interaction conditioning x sex was not significant (P=0.853), and sex did not influenced growth of calves (mean=357 g/d). Conditioning led to better BWG (507 vs 281 g/d; P=0.001) in the dry season and less morbility (P=0.001) than the control group. During the rainy season preconditioning increased 31 % the cumulative BWG in 112 d compared to control (370 vs 281 g/d; P=0.026). Concentrations of BUN (P=0.425) and SG (P=0.270) were similar between treatments. In conclusion, preconditioning of calves improved BWG postweaning, reduced morbility and loss of weight and BCS of lactating cows during the dry season.

Palabras llave : Pre-weaning; Conditioning of calves; Body weight gain; Dry tropics.