Effect of age on fertility and longevity of heifers
1993
Blaho, R. | Flak, P. | Ligacova, A. (Vyskumny Ustav Zivocisnej Vyroby, Nitra (Slovak Republic))
From the 1st up to 5th lactation, heifers (crossbreds of the Slovak Spotted breed with a hight share of the Black Spotted Holstein-Frisian breed) mated for the 1st time at different age, reached the following reproductory results: The lowest insemination index at the 1st getting-in as well as in the further period was found in cows with the lowest age of the 1st mating. The number of inseminations was significantly related to age. Regression coefficients moved from 0.02+ to 0.005++ (head per month). The average duration of service-period for the 1st up to 5th lactation was the lowest in the earliest, and the highest in the latest put of animals. The average age of cows according to the age of the 1st putting at culling was 1769.9 days (4.8 years), 1663.7 days (4.5 years), 1674.3 days (4.5 years), 1578.3 days (4.3 years), 1687 days (4.6 years), resp. the length of utility age was 1015, 878.4, 737.4, 745.0 days, resp..
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