C. Pascal

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C. Pascal, C. Cristian, I. Nechifor, A.M. Florea

   Many research enlightened the fact that heritability of reproduction and production characters at sheep is generally low, making difficult the selection for those characters. Nevertheless, exist also an obvious variation based on which could be improved reproduction and production performances. Lower heritability of characters was interpreted by Hansen in 1983 as a decreasing of additive genetic variation due to natural selection, aspect which gave to artificial selection a limited working margin.
   The analysed biological material belonged to Tigaie breed from private exploitations situated in the North-East part of Romania and represented by different age categories. Working method utilised for determination of characters' heritability was the one of restricted maximum probability (Restricted Maximum Likelihood - REML) because it is based on an iterative procedure and allow the obtaining of values in the normal space of parameters.
   The obtained results show the fact that at Tigaie breed, due to the fact that for calving weight the determined heritability was 0.25 meaning that basic selection of those character is not indicated, recommended being taking in consideration, for selection, live weight at 150 days because heritability coefficient increase at 0.36. Also, determination for mean values of heritability for some tissue characteristics of carcasses show that also those ones have a low heritability due to the fact that had h2 with values between 0.21 for fat quantity in carcass and 0.28 for total mass of carcass.
   Based on the obtained values for the majority of analysed quantitative characters, due those ones presented high values of variability show the existence of some adequate genetic resources to initiate some breeding programmes which will allow achievement of new reproduction and production performances for Tigaie breed.

Key words: Tigaie, sheep Romanien, meat sheep, parameters genetic