标题：Estimation of nonadditive genetic influences on standard lactation production (305 days) in upgrading of Serbian-Fleckvieh to Holstein-Friesian cattle breed
摘要：The purpose of this paper is to estimate the effects of systematic factors, primarily the degree of crossing, on the standard lactation lengths of 305 days in 6 different genotypes of cows (F1, R1, R2, R3, R4, R5) obtained by the upgrading of the Serbian Fleckvieh (SF) to the Holstein-Friesian (HF) breed of cattle. The systematic effects included in the general linear model (GLM) exerted a significant (P<0.05) influence on the milk yield, as well as the fat yield and content. During the upgrading process, statistically significant (P<0.05) differences were recorded between the traits of the genotypes examined. With an increase in the share of HF genes, the milk yield increased from 5020 kg (F1) to 5801 kg (R5) and the fat yield from 176.2 kg to 201.6 kg, whereas the fat content simultaneously decreased from 3.55 % (F1) to 3.49 % (R5). The F1 cows had the highest heterosis realized (hR) regarding the milk yield (185.8 kg), while the R1 and R2 cows displayed negative heterosis effects (-21.0 and -205.7 kg) and negative recombination effects (rI). The highest value of hR (regarding the milk fat yield) was recorded in the F1 cows (6.07 kg) in comparison with the R2 cows, which had the negative hR (-3.79 kg), whereas the negative rI was recorded in the R1 and R2 genotypes. The positive rI (regarding the milk fat content) was recorded in the R1, R2 and R3 genotypes accompanied by the positive hR.
关键词：upgrading; crossbreeding; recombination; heterosis; standard lactation length
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