Realization of the genetic potential of milk productivity of Holstein cows for an extended lactation period

Abstract

Cite this article: Honchar, A. O., Pishchan, I. S., Lytvyschenko, L. O., & Pishchan, S.G. (2019). Realization of the genetic potential of milk productivity of Holstein cows for an extended lactation period. Theoretical and Applied Veterinary Medicine, 7(2), 120‒125. doi: 10.32819/2019.71022 Abstract. The intensive conditions of industrial milk production require animals with a strong constitution and health, in order to maintain high levels of productivity and reproduction over a long period of time. The aim of the research was to determine the peculiarities of realization of the genetic potential of dairy productivity by cows during commercial exploitation in the industrial complex. An experimental part of the research was conducted on the industrial complex for the production of milk of Holstein breed cows of private JSC “Agro-Soyuz” (Ukraine) on healthy animals, which were formed in six groups from the first to the sixth lactation. With the intensive technology of exploitation in the industrial complex, the lactation activity of first-heifers and full-age cows varies within the range of 439.6–446.7 days, and the calving-to-calving interval is 497.3–506.3 days. At the same time, the relatively low milk productivity is characterized by first-heifers, in which the milk yield is 9,439.2 kg of physical or 9,091.6 kg of 4% milk, whereas in animals of the second lactation, these indicators are higher respectively by 10.03% (P < 0.05) and 11.17% (P < 0.01). In the fourth lactation observed further increase of milk yield, reaching the level of 11,725.3 kg of physical or 11,455.4 kg of 4% milk, which is more than the index of cows at third lactation, respectively, by 10.96% and 11.72%. Substantially higher milk productivity in cows at fifth lactation is 11,960.0 kg of physical or 11,833.9 kg of 4% milk, which is higher than the animals of the third lactation, respectively, by 12.70% and 14.54%. The highest milk yield have Holstein cows in the sixth lactation – 12,071.1 kg of physical or 11,919.9 kg of 4% milk, which is more than the animals of the third lactation, respectively, by 13.51% (P < 0.001) and 15.16% (P < 0.001). The production of milk butter and protein is the lowest in first-heifers and is an average of 661.2 kg. In animals of the second and third lactation, these products are higher respectively by 11.39% (P < 0.01) and 10.77% (P < 0.05), and in animals of the fourth to sixth lactation, by 20.72% and 22.96%. With the extended lactation activity, the correlation relation between live weight and total milk yield in first-heifers and cows of the second lactation is positive and is, respectively, r = 0.509 and 0.202. Instead, in cows of the third-sixth lactation, such the relation is negative and r = 0.339–0.163. In general, lactation animals of all ages are characterized by satisfactory adaptive properties: in cows in the fourth to fifth lactation, the adaptation index is on average –8.7 ± 0.34 units; in animals of the second-third lactation – respectively –9.6 ± 0.37 and –9.8 ± 0.53 units. The lowest value of adaptation index has first-heifers (–10,5 ± 0,44 units), and relatively the highest – in animals of the sixth lactation – –8,3 ± 0,24 units, which is less than the value of first-heifers on 26.51% (P < 0.001). The value of adaptation index has a functional relation with the total milk yield of Holstein cows of all ages and ranges from r = 0.426 in cows of the sixth lactation to r = 0.675 units in cows of the fourth lactation. Consequently, Holstein cows of the fifth and sixth productive periods are technologically adapted for intensive use.