Heritability and variance components estimates for growth traits in Saudi Ardi goat and Damascus goat and their crosses

Abstract

Objective: To study the genetic and non-genetic factors and their interactions affecting growth rate and body weights at birth, weaning and at 6 months of age in Saudi Ardi, Damascus goats and their crosses.Methods: Crossbreeding program between Saudi Ardi(A) goats with Damascus(D) was carried out to improve the meat productivity of Ardi goats through crossbreeding. The pedigree records of the body weights were obtained from 754 kids (397 males and 357 females) produced from 46 Sires and 279 Dams. Birth weight, weaning weigh and 6 months weight as well as average daily gain during different growth stages from birth to weaning (D1), weaning to 6 months (D2) and from birth to 6 months of age (D3) were recorded during winter/autumn and summer/spring. Data were classified according to breed, generation, sex, season, year, and type of birth. Data were analyzed using GLM procedure for the least-squares means of the fixed factors. Heritability and genetic parameters were estimated with derivative-free restricted maximum likelihood procedures using the MTDFREML program.Results: The percentages of variations were moderate for body weights and high for daily gains. Genetic groups had a highly significant (P<0.01) effect on the body weights traits. Damascus goats had higher (P<0.01) birth and weaning weights, but ½D½A group kids had a higher (P<0.01) body weight at 6 months. The genetic groups had a significant effects on the daily weight gains for D1 (P<0.01) and D3 (P<0.05) periods, whereas, it had no effects on D2 period. The fixed effects of sex, season, year and type of birth were significant differences for body weights. Male kids were heavier (P<0.01) than females for different growth stages. Body weights and daily gains during winter/autumn were significantly higher (P<0.01) than summer/ spring. Kids born and raised as singles were significantly (P<0.01) heavier than those were born as twins or triplets. The genetic and phenotypic correlations between birth and weaning weights were positive for both Damascus and Ardi goats.Conclusions: Genetic program for Ardi goats through upgrading with Damascus is possible to improve meat production.

Keywords

• Goat
• Heritability
• Heterosis
• Growth rates
• Genotype
• Phenotype