Efectos genéticos en el crecimiento predestete de corderos Hampshire.

The 30-day weight (P30; 1072) and the weaning (P75; 1750) of 10 flocks were analyzed in Hampshire lambs, to develop two objectives: to evaluate the expression of the genetic effects in the pre-weaning growth, and to analyze the possible implications in the genetic progress. The analyzes were univariate (ANAU) and bivariate (ANAB), through mixed models that included the fixed effects of contemporary groups and the covariable age of the mother; and as random, the direct and maternal genetic effects, the genetic covariance between them and the maternal effects of the permanent environment. Direct herilabilily (h²) and maternal (m²), genetic correlations (rdm), and genetic values (VG) were estimated. With the rank correlations (CR) in the VG, the ranking of the population and of the sire was analyzed; in addition, the genetic trends (TG) of the VGs were analyzed. The h² was in the range of 0.14±0.03 to 0.19±0.04; the m² in ANAU was 0.08±0.04 and 0.02±0.03, with ANAB the estimate was of 0.22±0.05 and 0.13±0.03. The rdm of ANAU was +1±0.15 in P30 and -1±0.18 in PD, changing in the ANAB to -0.46±0.10 and -0.20±0.07, respectively. The behavior of the TG in the ANAU was associated to the magnitude and sign of the rdm; likewise, the rdm of the ANAU implied changes in the ranking of sires, which was reflected in the TG and the CRs. [ABSTRACT FROM AUTHOR]