02052naa a2200325 a 450000100080000000500110000800800410001910000190006024501200007926000090019952011260020865000170133465000240135165000170137565000100139265000130140265000340141565000100144965000190145965300170147865300110149565300270150665300180153365300180155165300210156965300250159070000290161570000220164477300600166619125222016-01-22       2012    bl uuuu     u00u1 u    #d1 aLOBO, R. N. B.  aGenetic (co)variance components for ratio of lamb weight to ewe metabolic weight as an indicator of ewe efficiency.  c2012  aData from a multibreed commercial flock located at Mid-West of Brazil, supported by Programa de Melhoramento Genético de Caprinos e Ovinos de Corte (GENECOC),were used to estimate genetic parameters of traits related to ewe productivity by Average Information Restricted Maximum Likelihood method applied to an animal model. The analyzed traits were litter weight at birth (LWB) and atweaning (LWW), eweweight atweaning (EW)and ewe production efficiency, estimated by WEE=LWW/EW0.75. The heritabilities were 0.26±0.05, 0.32±0.06, 0.37±0.03 and 0.10±0.02 for LWB, LWW, EWand WEE, respectively. Significant effects for direct heterosis were observed for LWWand EW. Recombination losseswere important for EWandWEE. Genetic correlations of LWBwith LWW, EWandWEEwere 0.68, 0.37 and 0.15, respectively; of LWWwith EW and WEE were 0.30 and 0.34, respectively; and between EW and WEE was ?0.25. Even though it is a low heritability trait, WEE can be indicated as a selection criteria for improving the ewe productivity without increasing the mature weight of animals due to its genetic correlations with LWWand other traits.  aBirth weight  aGenetic correlation  aHeritability  aSheep  aCordeiro  aMelhoramento genético animal  aOvino  aPeso ao nascer  aAnimal model  aBrasil  aCorrelação genética  aHerdabilidade  aModelo animal  aMultibreed flock  aNon-additive effects1 aFERNANDES JÚNIOR, G. A.1 aLOBO, A. M. B. O.  tLivestock Science, Amsterdamgv. 143, p. 214-219, 2012.