Dynamics of milk productivity and service period by lactation in cows of different lines

Abstract

Abstract. The purpose is to study the dynamics of milk productivity and service period of Holstein black-and-white cattle by lactation, depending on origin. Methods. Milk productivity was assessed by the method of control milking, milk quality indicators – by the instrument method on the Lactan-1M device, reproductive qualities – by conventional methods. Results. The breeding farms breed animals that belong to the following genealogical lines: Vis Back Ideal, Reflection Sovering, Montwick Chieftain, Pabst Governor and Siling Trijun Rockit. The main livestock is represented by 3 lines. Most of the cows belong to the Vis Back Idial line – 55 % of the total livestock of more than 11.5 thousand heads, of which 61.51 % for the 1st and 2nd lactation. The dynamics of changes in milk yield during lactation confirms a well-known pattern, increasing to full-age 4th lactation. The greatest significant increase was found on the 2nd relative to the 1st (P ≤ 0.01). From the 5th lactation, milk yield gradually decreases by 9.4–9.8 % for each subsequent lactation. The effect of the duration of the service period on milk productivity has not been established. KVS is 0.86 on average for livestock, which allows us to conclude about certain problems with reproduction in cows of this line. The productive longevity of cows of this line is 2.36 lactation. The group of cows of the Reflection Sovering line includes 31.5 % of the total number of dairy cows with a share of young cows of 70.1 %. The duration of productive use is lower and amounts to 1.95 lactation, and the coefficient of reproductive ability varied depending on lactation from 0.88 to 0.93, reaching a maximum of 0.96–0.98 in the 9th and 10th lactation. The longest duration of productive longevity was established in the group of cows belonging to the Siling Trijun Rokita line, which are used for 5.6 lactation, more than 41 tons of milk were obtained from them, but lower productivity indicators were revealed. In general, there is an increase in milk yield in livestock, which leads to a decrease in productive longevity. Materials of breeding and zootechnical accounting of the Selex database, breeding cards of cows were used for research. The scientific novelty of the work lies in the fact that the influence of origin on productive longevity has been proven, which allows through breeding work to have a positive effect on increasing the duration of productive use.

Evaluation of the productive qualities of Holstein dairy cattle

“…In the process of their operation, certain problems have been identified, which are related to: a decrease in the duration of productive use, which is associated with a deterioration in reproductive abilities; increased demands on feeding and housing, etc. [5][6][7][8]. The productive qualities of cows are influenced by many factors, including genetic ones, such as genotype, selection method, and origin.…”