Resumen

GONZALEZ-DOMINGUEZ, Gabriel et al. Preweaning growth analysis of Blackbelly lambs in hot humid weather. Nova scientia [online]. 2016, vol.8, n.17, pp.181-197. ISSN 2007-0705.

To estimate genetic, non-genetic and environmental effects on the response variables birth weight (BW), adjusted weaning weight (AWW) and preweaning average daily gain (ADG) in Blackbelly lambs in Af(m) warm-humid climate, a retrospective observational study of a farm of Tabasco state, Mexico was carried out. Heritabilities of BW and AWW were estimated and a progeny test of sires was performed. Records of 650 BW, 445 AWW and the ADG were used from years 2000, 2002 and 2004. WW and ADG were adjusted to 102 d of age. Two analyzes were made: the first model included the fixed effects of sex (male and female), type of birth (single and multiple), number of parity (primiparous and multiparous), the sire effect and year-season as a blocking factor. In the second analysis, a mixed model that included the above fixed effects and the random effect of sire (eight to BW and seven to ADG and AWW) within year-season was used. All independent variables affected the BW (P < 0.01). The sires affected preweaning ADG and AWW (P<0.01). The AWW was affected by number of parity. Lambs from multiparous ewes were heavier at birth and weaning with respect to lambs from primiparous. In the studied animal population, the estimated heritabilities values were 0.16±0.05 and 0.48±0.03 for BW and AWW, respectively.

Palabras llave : Hair sheep; humid tropic; lactation; heritability.