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Structure and the non-genetic and genetic effects on milk traits in Polish dairy goat population

Emilia Bagnicka
Polish Academy of Sciences, Institute of Genetics and Animal Breeding in Jastrzębiec, 05-552 Magdalenka, Poland
Abstract :
The aims of this study were to analyse the structure of Polish dairy goat population and to estimate
the non-genetic and genetic sources of variation in five milk traits. The data set comprised 18,563
lactation records of 8,938 dairy goats, while the pedigree file covered information on 13,159 animals
6 generations deep. To estimate the environmental effects the GLM procedure, using a model with
the random effect on the herd-sire interaction, the fixed effects of herd-year-season of kidding
interaction, breed, litter size, parity, year of birth and regression on day-in-milk. To estimate the
co(variance) of the components of milk, fat, and protein yields, as well as fat and protein contents
the REML method based on the repeatability animal model was applied. The average inbreeding
coefficient was 0.61% (sd=3.12%). Milk, fat and protein yields were affected by all the factors
except for breed. The nanny goats with more than two kids had higher milk, fat and protein yields,
but they had a lower percentage of milk components than those with one kid or twins. The goats
in their first lactation had the lowest milk, fat and protein yields, but the highest fat content. The
heritability estimates were moderate (0.21, 0.18, 0.19 for milk, fat and protein yields, respectively).
Repeatability estimates ranged from 0.30 for milk, 0.28 for fat, and 0.27 for protein yields, and 0.25
and 0.28 for fat and protein contents. Genetic correlations between milk yield and fat and protein
contents were negative and moderate (-0.27 and -0.30), between fat and protein contents (0.58) while
those between yields were ranged from 0.71 to 0.86. In turn, correlations between fat yield and its
content, and protein yield and its content were positive and moderate (0.35, 0.23).
Keywords :
dairy goats / genetic parameters / production traits

Date Deposited : 02 Apr 2015 14:05

Last Modified : 02 Apr 2015 14:05

Official URL:

Volume 33, Number 1, - 2015

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