THE MILK PRODUCTION VARIABILITY OF MOLDOVAN KARAKUL EWES
The research purpose of this work was to identify and assess the main factors that determine the milk production variability of Moldovan Karakul ewes and selection efficiency according to this character. The research was done on lactating ewes of the Karakul sheep flock from National Institute of Animal Husbandry and Veterinary Medicine, from the village of Maximovca, Anenii Noi district, Republic of Moldova. Ewes milk production was determined, by milking control, systematically done at every ewe, once every 15 days, throughout whole lactation. Variability of ewes milk production was examined according to their age (lactation) and fodder conditions of different years. The character of ewes lactation curve, in these years, was examined, in function of the average milk quantity, obtained daily, depending of ewes calving terms. The research has shown that the ewes milk production depends on the genotype of the parents. From the ewes mothers, with increased milk production, of over 110 kg, were obtained progeny daughters, with milk production, also increased, on average of 87.10 ± 8.24 kg. The hereditary power and the influence degree of parental genotype on the variability structure of the milk production, are expressed by the heritability coefficient value (h2), which was 0.316. The data obtained show that 2/3 of the total phenotypic variability of milk production is determined by external factors, such as forage conditions of the year and the ewes calving terms. Thus, in years when satisfactory forage conditions, ewes milk production was on average over 80 kg and in the forage conditions less satisfactory, it was comprised only up to 70 kg. The late calving ewes (February, March) had an average daily productivity for the whole lactation less (381-554 g/day) compared to early calving ewes (April, May), which had a productivity of 428-616 g/day. The ewes lactation curve, in effect, represents a line increasing slowly from 500-700 g/day at calving, up to 600-700 g/day at 6-7 weeks, and with a slowly decrease up to 100-200 g/day at 25 - 27 weeks after calving. Biological curve (theoretical) of Moldovan Karakul ewes lactation, in the optimal nutrition conditions and care represents, in our view, a straight line with a relatively high level, starting from calving with 700-800 g/day, remaining at this level up to 13 - 14 weeks, with a slow decrease after up to 150 - 200 g/day in the range of 25 to 26 weeks after calving. The ewes milk production is based on their age at calving. The maximal quantity of the milk production at this race is performed starting with the age of 4.5 years, or with the third lactation. The ewes in the first lactation reach the milk production at the level of 74.3 % and in the second lactation - at the level of 90.3 %, compared to the ewes in the third lactation.
Key words: milk, Karakul ewes, variability, heritability, lactation curve