Genetic parameters for body weight of egyptain farafra lambs with random regression model

الملخص EN

Genetic parameters of body weight were estimated for a total of 13996 records of Farafra lambs.

Data were collected during the years 1991-2001 from a single experimental sheep flock raised under accelerated lambing system and belonging to Animal Production Research Institute (, El-Menia Governorate, Egypt) Lamb body weights were measured at birth (wt0) and monthly thereafter up to 12 month of age (wt12).

Lamb weights were analyzed using random regression model (RRM) to estimate (co)variance components.

Fixed effects included in the mixed model were year-season of birth, age of dam at lambing, type of birth and sex of lamb.

Heritability estimates were 0.36, 0.37, 0.37, 0.33, 0.32, 0.32, 0.32, 0.34, 0.35, 0.35, 0.35, 0.33 and 0.30, respectively.

The corresponding permanent environmental effects were 0.59, 0.55, 0.53, 0.59, 0.63, 0.64, 0.64, 0.63, 0.63, 0.63, 0.63, 0.65 and 0.69, respectively.

Genetic correlations between each pair of weight records varied from -0.27 to 1.00.

Phenotypic correlation ranged from -0.35 to 0.97.

In view of the obtained results, genetic selection to improve body weight in Farafra lambs is expected to have good response from birth to 8 weeks of age.