RESEARCH ON THE CORRELATION BETWEEN THE AGE AT THE FIRST CALVING AND MILK PRODUCTION CHARACTERS

TL;DRAbstract

The paper aimed to present the genetic determinism of milk yield traits and age at first calving using a number of 2,237 half sibs, offspring of 989 Friesian bulls and raised in various farms in Romania. Taking into account the peculiarities of half sibs families, it was used a linear mathematical model for unbiased cross classification. Average 305-days milk yield at the first lactation was 3,034.88 ± 14.67 kg, while the average milk fat percentage registered 3.79 ±0.004 %. Average 305 days fat yield accounted for 115.12±0.59 kg, average age at first calving regietered 839.25±1.43 days ( 27.5 months). Between milk yield and fat percentage, it was found a correlation of rG - 0.245, reflecting a weak but positive relation between the two traits. The phenotypic correlation was low and a negative one (rF = -0.181), showing a weak and reverse link between the two traits. Between milk yield and fat yield, both the genotypic and phenotypic correlations were very high and had positive values,

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