Genetic and Non-Genetic Effects on Body Weight of West African Dwarf Sheep

The purpose of this study was to evaluate the genetic parameters of monthly weights from birth to 180 days and of preweaning daily gain (0-90 days) and post weaning (90-180 days) of West African Dwarf sheep from the Betecoucou breeding farm of Benin Republic. The variance and covariance component for growth traits were estimated using Multiple Trait Animal model and Sire model. The average Weights at Birth (BW), 30 days Weight (W1), 60 days weight (W2), 90 days (W3), 120 days (W4), 150 days (W5) and 180 days weight (W6) were 1.93 +/- 0.02, 4.25 +/- 0.06, 7.60 +/- 0.12, 10.97 +/- 0.12, 13.58 +/- 0.15, 14.85 +/- 0.20 and 17.30 +/- 0.21 kg, respectively. The pre and post weaning Average Daily Gains were 100.41 +/- 1.30 g day (ADGH and 71.08 +/- 1.70 g day(-1) (ADG2), respectively. The sex of lamb, birth type, parity of ewe, season and year of birth, revealed significant effects on all weights and daily gains using the General Linear Model procedure (proc GLM) of SAS (R). Estimates of heritability from animal model and sire model were 0.43 and 0.44 (BW), 0.10 and 0.07 (W3), 0.13 and 0.09 (W6), 0.05 and 0.05 (ADG1), 0.10 and 0.05 (ADG2), respectively. From sire model, heritability estimates were 0.20 (W1), 0.25 (W2), 0.08 (W4) and 0.10 (W5). Genetic and phenotypic correlations ranged from -0.02 to 0.87 and -0.16 to 0.95 in the animal model and from -0.21 to 0.99 and -0.20 to 0.99 in the sire model. Selection for body weight would not affect other weight but could increase probably the frequency of dystocia and to avoid this situation, selection of heavier W1 could be used.