INFLUENCE OF THE DEVELOPMENT OF LINEAR CONFORMATION TRAITS CHARACTERIZING THE BODY STATE, ON THE VIABILITY OF COWS UKRAINIAN BROWN DAIRY BREED
Authors: Ladyka V. I. , Hmelnychyi L. M. , Hmelnychyi S. L. 
Published: December 2019

In the aspect of the search for predictors of longevity of dairy cattle animals, the dependence of longevity of Ukrainian brown dairy cows on indicators of descriptive conformation type traits has been investigated. We studied the linear type traits of the exterior of first-calf cows in the leading farms of the Sumy region, characterizing the state of the body development.

According to the results of this research was determined, a reliable dependence of the cows longevity on the level of assessment of the descriptive conformation type traits: chest width, body depth, angularity, rump angle and width, and body condition score. The correlative variability of the relationship between cow’s longevity and these features was depending on the level of assessment of specific type trait of body structure of the animal.

Dependence of the cows longevity on the development of chest width was different by curvilinear variability. The longer life of cows was found in animals with an estimate for the development of this type trait at 4–6 scores that averaged 2.726–2.895 days with the best 5 scores. When comparing the group of animals with an average 5 scores with the groups having 6–9 scores, a significant difference was found in favor of the first, ranging from 169 (P < 0.01) to 561 days (P < 0.001).

Studies on the dependence of the longevity of brown cattle cows on the value of body depth assessment have shown that the most longevity was inherent in animals estimated by type trait development at 7–9 scores, with the highest rate in 2.856 days and estimate – 7 scores.

The type trait of angularity similar to deep-chested and was also directly related to the cow's longevity. Cows with excessive angularity and the highest lifetime (2.713–2.855 days) were estimated by the higher scores (7–9) with the best evaluation results in 8 scores. A significant decrease in cows longevity was observed with a decrease in the assessment for this trait starting from 6 scores (-244 days; P < 0.05) to 1 (-701 days; P < 0.001) compared with the best result of 8 scores.

The desired state of the linear trait development, the rump angle, was within the average assessment level of 5 scores, which similar to the optimal sacrum slope between the extreme points on the conditionally drawn line at the level of the top point of hip bones and the ischial hump, which was 2–4 cm. Deviations towards the assessment of the rump angle to 1 score (raised) or 9 scores (sloped) are the disadvantages of the body structure. The study of this trait has shown the curvilinear nature of the relationship between estimates for the state of rump angle and longevity of cows. Cows with an optimal 5 scores rating had the highest longevity of 2.796 days, while with increasing and decreasing estimates, the number of days of life of cows decreased.

The longevity of cows of brown cattle was determined on the level of assessment for the trait of the rear width. Cows with a maximum estimate for the state of this descriptive trait in 9 scores were used for 575 days longer compared to animals rated at 1 score (P < 0.001).

According to the results of research of animals by the trait of body condition, it was found that the degree of fatness was associated with the longevity of brown cattle in the opposite direction. That is, a thinner animals, which are valued lower scores, and used to live much longer. The influence of body condition score on the longevity of animals was confirmed by the highly reliable difference between the maximum (9 scores) and the minimum (1 score) estimates, which was 457 days (P < 0.001). A significant decrease of the longevity was observed in cows with an assessment of body condition in 6–9 scores.

Thus, the existence of a correlative variability between estimates of descriptive traits of conformation type and the longevity of cows of Ukrainian brown breeds was determined. Each of the estimated type traits of the body structure correlates with the longevity of cows with varying variability within the classification scores in accordance with their desired development. Thus, the selection of animals for the desired development of linear traits at the age of the first lactation allows them to be used as indirect predictors to increase the duration of use of cows.