NEW RESEARCHES CONCERNING VARIABILITY OF MILK PRODUCTION AT THE MOLDAVIAN KARAKUL EWES
The purpose of this paper was to the revelation of phenotypic correlations of milk production with some morph-productive characters of organism ewe and lamb descendent that influence variability of this production at the Moldavian Karakul ewes. The research was conducted on lactating ewe from flock of sheep of National Institute of Animal Husbandry and Veterinary Medicine from Maximovca village, Anenii Noi district, Republic of Moldova. The ewes milk production was determined by milking control, systematically conducted at every ewe once in 15 days during the whole lactation, according to the Instructions of evaluation of Karakul sheep with improve principles, approved by the Technical and Scientific Ministry of Agriculture and Food. Were investigated correlative connections of the ewes milk production with body weight and skin own qualities (class and type of curls) of the ewe, also with and body weight at birth lamb-descendent and skin qualities (class of evaluation expressed points) in its evaluation marks. It was found, that milk production of Moldovan Karakul ewes is in linear curve relationship with their body weight. This means that with weight gain of ewes up to a certain level (in our case - 60 kg), their milk production is increasing. After reaching the optimum level of body weight, the ewes' milk production tends to decrease. The coefficient value of linear correlation is small and close to zero (rxy = 0.024 - 0.043) but linear curve nature of this relationship is confirmed by the correlation attitude (ηxy = 0.186 - 0.285) which is significant (P < 0.05). The ewes milk production is not in physiological (genotyping) relationships antagonistic qualities of their skin, because have been not detected any significant correlations between skin own qualities (class and type of curls) evaluation marks we have at the moment after ewe birth at the age of lamb and its milk production after calving there of. Between the milk production of ewes-mother and the skin qualities of descendents lambs there is a positive correlation, direct linear and significant (rxy = 0.133 ± 0.062; tr = 2.14; P <0.05). This correlation additive influence on the selection process geared both towards improving milk production and the skin lambs qualities in the flock. Between the lamb body weight at the birth and the ewe milk production, what have been obtained in lactation that following after the birth of this lamb, there is a correlation quite close, directly linear high significance (rxy = 0.460 ± 0.055; tr = 8.36; P <0.001). The existence of positive correlation between these two important morph-productive characters favoring selection efficiency by both characters, obtaining the additive effect in its improvements. In the researched flock, the coefficient of direct linear regression of the milk production depending on lamb body weight at birth have been was Rx/y = 12.20 ± 0.09 kg, what it means, that with increasing of body weight of lambs at birth with 1 kg, the ewes milk production will increase on average by 12.2 kg.
Key words: Karakul ewes, milk production, variability, phenotypic correlation