ASPECTS QUANTITATIFS DE LA PRODUCTION LAITIÈRE DES BREBIS. III. - COEFFICIENTS D'HÉRITABILITÉ

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Abstract
Heritability coefficients of the different criteria characterizing milk production in the Lacaune ewes in the Roquefort region were estimated. We retained for this study 651 dam-daughter couples known by their 1-year-old performances, 830 known by their 3-year-old ones, 326 known by their 4-year-old performances and 1251 by the average of all adult (3-years and more) lactations. The production averages of this sample were higher than those of the total ewe population recorded in Roquefort. The intra-flock heritability coefficients and their confidence limits were 1st estimated. Thereafter the adjusted heritability coefficients were calculated, after correction for the year and year-flock effect, the non-genetic differences between flocks, and the limited number of maternal grand-fathers in the sample. For the 1- and 3-year-old ewes the corrected heritability coefficients obtained were respectively 0.43 and 0.26 for total milked yield, while being 0.50 and 0.23 for the maximum daily control yield and 0.54 and 0.11 for the average daily yield. The validity of these estimations was also discussed. The author must note here the similarity of these results to those generally obtained with dairy cattle and underline the great interest of an early selection based on the 1-year-old milk performances.

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