Objective: to study the dependence of productive longevity of cows of black and motley breed on genetically determined factors - linearity and bloodiness in Holstein breed.
Methods: zootechnical, biological, statistical.
The materials of the studies were pedigree cards of cows and bulls, bull catalogs, zootechnical reports on pedigree work with the herd, the cattle base of the Grodno region, and also registers of rearing and rearing of the litter.
To study the effect on the longevity of cows and their lifelong productivity of the "linear accessory" factor, all animals that were eliminated in 2006-2014 were divided into groups according to the lines: Adema 25437, Annas Adema 30587, Vis Eidial 933122, Montvik Chiftein 95679, Nico 31652 , Pabst Governera 882933, Reflection Sovering 198998, S. Sensation 1267271, Hiltes Adema 37910.
Depending on the bloodiness of the Holstein breed, the animals were divided into four groups: I - up to 25% of Holstein genes, II- 25,0 – 49,9% of the genes of the Holstein genus, III - Holstein blood 50% and more, IV - purebred black-motley cows.
Indicators of milk productivity (life-time milk yield (kg) and lifetime yield of milk fat (kg), milk yield for 1 day of lactation (kg), total duration of the lactation period (days) were studied in the experimental animals, and the duration of economic use (lactations).
Main results. The results obtained during the statistical processing of data indicate that the cows belonging to the Pabst Governera line 882933 differed in the longest period of economic use among the abandoned animals. Duration of use in animals of this line was 8.43 lactations, which is more than for cows of other lines at 1,72-6,67 lactation. It should be noted that cows belonging to the Adem 25437 lines (6,71 lactations) and S. Sensation 1267271 (5,49 lactations) were also characterized by a rather long period of economic use.
Due to the long period of use of the cow, the Pabst Governera line 882933 had the highest indicator of lifelong milk yield – 51535,58 kg of milk and the yield of milk fat – 1914,03. But as for milk for one day of lactation, here the leadership belonged to individuals belonging to the line Vis Eidial 933122 and amounted to 21,19 kg of milk per day. Also, a fairly high indicator of milk yield for one day of lactation was observed in animals belonging to the line Montvik Chiftain 95679 – 21,02 kg of milk.
As a result of the research it was found that the largest term of economic use was characterized by low-breed hybrids with Holstein breed (up to 25%) – 3,63 lactations. This group of animals exceeded the individuals of the remaining groups by 0,21-0,76 lactations. It is worth noting that purebred black-motley individuals also differed by a long period of productive use – 3,42 lactations.
Conclusions. Analysis of the impact on productive longevity and indicators of lifetime productivity of the "linearity" factor among abandoned animals in the "Progress-Vertelishki" made it possible to establish the existence of significant differences in the duration of economic use of cows of different linear affiliation. Cows of the Pabst Governera line 882933 – 8,43 lactations, 51535,58 kg of milk and 1914,03 kg of milk fat were distinguished by the greatest period of productive longevity, and also by the highest milk yield and milk fat content. It was established that the crossing of black and white cattle with Holstein breed positively influenced the productive longevity of animals, but on condition that the blood on the improving rock did not exceed 25%. Low-breed hybrids with Holstein breed exceeded the animals of other groups by the duration of their economic use by 0,21-0,76 lactations. Thus, we recommend breeding cows of black and motley breeds in the "Progress-Vertelishki", taking into account the impact on productive longevity and milk productivity of such factors as linearity and bloodiness in Holstein breed.
EFFECT DEGRADABLE PROTEIN LEVEL G/MJ METABOLIZABLE ENERGY THROUGH DIFFERENT STAGES OF LACTATION ON MILK YIELD AND COMPOSITION OF AWASSI EWES
