RESEARCH ON COMPARISON OF BREEDING VALUE METHODS FOR SHEEP MILK PRODUCTION.

The aim of this paper is to compare four methods for estimating the breeding value of sheep, for the milk production. The research was conducted at the National Institute of Research and Development for Biology and Animal Nutrition Balotesti, Ilfov. The biological material is represented by a flock of Palas Milk line, consisting of 805 animals: 344 downward, 121 rams and 340 sheep. The character analyzed was the amount of milk in the weaning lamb period to the end of the lactation. Lactation length was between 51 and 230 days. To estimate heritability (h2) and breeding value, BLUP methodology applied to an animal model was used. The heritability value was estimated by the method of single factor analysis of variance, and was 0.73. By the animal model, the heritability was stabilized at 19 1iterations, the value being 0.235. The breeding value was estimated in four ways: a) Performance (PP); b) Average performance of paternal half-sisters (PSS); c) LUSHIndex(IL); d) Individual Animal model (IAM). The best work option was comparatively analyzed through Spearman rank correlation and selection accuracy. The highest rank correlation was obtained with the combination IL -IAM, 0.82 respectively, due to the fact that the methods used commonly a high sources and amount of information. The opposite is the combination of IAM-PSS, where rank correlation is -0.0071. In terms of selection accuracy, the highest value was recorded for the IAM (0.52) and the lowest inbreeding value estimation based on PP (0.48), which indicates a superiority of IAM of 8.33%. In conclusion, to achieve a more precise evaluation of animal breeding, all available sources of information should be use in calculations. Also, the combination of these sources is recommended to be performed by using BLUP methodology, applied to an animal model. [ABSTRACT FROM AUTHOR]