The Assessment of the Adaptability of Jersey Breed Cows

Abstract

The results of the studies carried out highlight the assessment of the adaptive ability of Jersey cows. The conditions of keeping Jersey cows in the Dan Milk subsidiary contribute to the realization of high milk productivity, which is due to heredity, but cause a deterioration in their reproductive capacity.
 At the same time, a high manifestation of milk productivity and satisfactory reproductive ability have observed only in the daughters of DJ Jante 302761 – whose adaptation index was closer to zero and amounted to -2.7. The force of influence (ηx2) of paternal origin on the signs of milk production in first-calf calfs was 21.1% versus 5.9% of the generalized mean value for cows belonging to the line.
 It has been founded that according to the adaptation index, the state of animals those characterized by the absence of harmonious interaction with the environment – cows show high productivity with a significant deterioration in reproductive capacity, which indicates the presence of a feedback between these characteristics.
 It was found not high enough, but statistically significant influence (P < 0.01 – P < 0.001) on the adaptation level of first-calf cows by milk yield for 305 days of lactation (8.0%), milk fat and protein (7.0%). A statistically significant effect (ηx2 = 82%) of the signs of reproductive ability of cows (service period and period between calving) was found depending on their level of adaptation (P < 0.001).
 With an increase in the level of milk production of cows, was established a clear connection between the deterioration of the adaptive qualities of livestock. So with an increase in milk yield for the entire lactation from 6000 to 10000 kg of milk, the adaptation index decreases from -0.5 to -9.5, which is confirmed by a statistically significant difference between the extreme groups of animals with different levels of productivity (P < 0.001).
 According to the adaptation index, the condition of animals were characterize by the lack of harmonious interaction with the environment - cows show high milk productivity with a significant deterioration in reproductive capacity, which indicates the inverse relationship between these traits.
 The influence of the father and belonging to the lines on such indicators of milk productivity as: yield for 305 days of lactation, milk fat and protein (P < 0.05 – P < 0.001) was statistically significant. Significant effect of increasing the level of milk yield of cows was observed on such signs of reproductive capacity as: service period, period between calves and reproductive ability coefficient (P < 0,001). There was no statistically significant effect of belonging to the lines and offspring of specific breeders on the signs of reproduction of cows in general (P > 0.05). We found that the reproductive quality of cows is more influenced by the level of milk yield of cows during lactation (23.1%, at P < 0.001), which is confirmed by our previous studies.
 The conditions of keeping Jersey cows in the Dan Milk State Enterprise contribute to the realization of high milk productivity, which is due to heredity, but causes a deterioration in their reproductive capacity.