Heritability for reproduction traits in Polish and Norwegian populations of dairy goat

Abstract

Estimation and verification of the variance components of the reproduction traits in dairy goats was the purpose of the investigation. The study included Polish and Norwegian populations. Since the numbers of goats were generally lower and the pedigree information poorer, in the Polish population, the results obtained for the Norwegian one were treated as the reference. The Polish data included records on 9283 goats maintained in herds from 1983 till 2001. The information on the first parity litter size (LS1), number of kids born alive (NBA1), and total losses (TL1) regarded 8479 does while the data on the second parity traits (LS2, NBA2, TL2) included 5729 does. Age at first kidding (AK1) was known for 7370 does and age at second kidding (AK2) and kidding interval (KI)—for 4545 does. The pedigree included 13 618 animals with the eldest born in 1977. The Norwegian data set covered 68 240 does with 64 903 having recorded LS1 and K1, 51 266—LS2 and AK2, and 45 704—KI. The goats were maintained from 1991 till 2002. The pedigree data covered 150 677 animals with the eldest born in 1966. The variance components were estimated with the REML method using animal model. The heritability estimates of LS1, NBA1, TL1, and AK1 were 0.14, 0.11, 0.04, 0.13; of LS2, NBA2, TL2, and AK2—0.11, 0.09, 0.04, and 0.13, in the Polish population. The heritability of KI reached only 0.015. In the Norwegian population the heritabilities of LS1, LS2, and KI were 0.18, 0.13, and 0.03, respectively. The estimates of heritabilities in the second parity were lower or at most equal to those in the first one. The magnitude of the heritability estimates for LS1, LS2, NBA1, and NBA2 indicate possibility of an effective selection for those traits.