Efeito da endogamia direta e materna sobre características de prolificidade de suínos Landrace e Large White

Abstract

Data from Landrace (LD) and Large White (LW) sows were used to quantify the levels of direct and maternal inbreeding and evaluate their effects on litter traits for total number of piglets born (NNT), number of piglets born alive (NNV) and number alive at day 5 after birth (NV5). Was utilized the method of least squares by linear regression to assess some proposed models based on the variables studied. The full model described the NNT and NNV traits included the following variables: contemporary group, mother's birth year litter, reproductive cycle (linear and quadratic), direct and maternal inbreeding. For NV5 feature, the variable maternal inbreeding was excluded from the model, due to the practice of exchange between different litters of piglets during lactation. The inbreeding coefficients were found for NNT 0,38 piglets /% (maternal) e 0,12 piglets /% (direct) breed LW e 0,16 piglets /% (maternal) e 0,03 piglets /% (direct) breed LD. For NNV were found to -0,02 LW piglets /% (maternal) and 0,11 piglets /% (direct) and LD -0,003 piglets /% (maternal) and 0,004 piglets /% (direct). For NV5 values obtained were LW 0,09 for piglet /% (direct) and breed LD -0,009 piglets /% (direct). The results suggest that selection for NNT characteristics NNV and NV5 is effective for survival of piglets, even in a virtually closed breeding nucleus. In general, maternal and direct inbreeding coefficients suffered highs during the study period, possibly due to the efficiency of selection of the most prolific female in the litter, born in previous years. Even though there were rising inbreeding coefficients from year to year, it has not identified the occurrence of inbreeding depression.