The effect of a low level of inbreeding on characters of linear evaluation of the exterior of holstein cows

The objective of the present study was to evaluate the effect of a relatively more frequent occurrence of lower coefficients of inbreeding in a population of Holstein cattle on the exterior characters. The exterior of inbred cows (on the level of Fx = 1.56 – 4.00%) was compared with their outbreed contemporaries, i.e. half-sisters from the same father. Evaluations of the exterior of both inbred cows and contemporaries were conducted on the same day, 60-180 days after the first calving, in the same barn and using the valid mode of operation “Linear description and evaluation of the exterior of Holstein cattle”. The group consisted of 212 inbred cows and 521 contemporaries. This monitoring is part of a more extensive study dealing with the effect of low levels of Fx coefficients on the characters of milk performance. On that score, the evaluations primarily include characters that are associated with milk production.The group of inbred cows was compared with their contemporaries and the increased variability of all the evaluated characters (Vx) was studied. The increased variability was particularly due to the wider variance of characters and/or due to the more frequent occurrence of the characters, in inbred animals including both biological extremes (maximum and minimum). Compared to the contemporaries the average values of exterior characters of inbred animals were lower. The most marked decrease in the values was detected for the fore udder attachment (0.28 points, i.e. 5.5 %) and for the total evaluation of the legs (-0.80 points, i.e. a 1.04% decrease). Although the worsening of the exterior of inbred animals involved all the characters under study, compared to the outbreed contemporaries the differences on the studied level of Fx were not statistically significant.

Abstract licence: CC BY-NC-ND

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