Biotechnology in Animal Husbandry 2011 Volume 27, Issue 4, Pages: 1433-1441
https://doi.org/10.2298/BAH1104433P
Full text ( 364 KB)
Regression analysis of milk production traits in simmental cows
Petrović M.D. (Faculty of Agronomy, Cacak)
Bogdanović V. (Faculty of Agriculture, Belgrade-Zemun)
Petrović M.M. (Institute for Animal Husbandry, Belgrade-Zemun)
Rakonjac S. (Faculty of Agronomy, Cacak)
The relationship between milk production traits over whole lactations was
evaluated across three generations of Simmental cows, i.e. between daughters,
dams and grand dams, by a phenotypic regression analysis with whole lactation
traits in the daughter generation being used as the dependent variables (x1),
and those in the dam and grand dam generations being used as the independent
variables (x2 and x3). The results were obtained from a sample of 1170
daughters and as many dams and grand dams. The significance of the partial
regression coefficients b2 and b3 was separately evaluated by a t-test. An
analysis of variance was used to estimate the significance of the
simultaneous effect of the production traits of dams and grand dams on the
milk production achieved in the daughter generation. The calculated value of
the partial regression coefficients for the whole lactation production traits
across three generations (grand dams, dams and daughters) and their
statistical significances determined by the t and F tests, as well as the
regression equations used, suggested that the effect of the grand dam
generation on the milk production traits in granddaughters was substantially
lower than the effect of dams. The calculated partial regression coefficients
(b2 and b3) were positive and statistically very significant (P<0.01),
excepting the regression coefficients b3 for lactation length and b2 for milk
fat content that were not statistically significant (P>0.05). A very
significant change (P<0.01) was observed in all production traits in the
daughter generation as simultaneously affected by the traits in the dam and
grand dam generations.
Keywords: Simmental breed, production traits, generation, regression