Всероссийский научно-исследовательский институт физиологии, биохимии и питания животных – филиал Федерального государственного бюджетного научного учреждения «Федеральный научный центр животноводства – ВИЖ имени академика Л.К. Эрнста»
ABSTRACT. The aim is to analyze empirical data on the dynamics of survivability of Black-and-White cows to identify patterns in the relationships between obtained parameter estimates. The material of the study was the data of production records of the age composition of a herd of cows in 21 production herds of Leningrad oblast in the period 1985-1990. The culling rate of cows for the sum of reasons was described by the exponential Gompertz function, the values of the pre-exponential parameter B and exponent index c were determined from the age structure of the herd (number of cows with consecutive lactation numbers) averaged over 5 years to compensate for deviations from stationary regime of herd turnover. A negative correlation between the parameters B and c was found for the 16 production groups studied (c = 0.19 - 0.15*B, R2 = 0.69). In the computer simulation experiment, an analogous correlation was obtained on the assumption that the herds are heterogeneous in the survival dynamics, and the constituent groups (subpopulations) have the same value of "c", but the unequal values of B and the different initial group sizes. For 16 model subpopulations, a negative correlation was found between the mean life span of T (the average number of lactations) and the parameter B (T = 5.12 - 6.73*B), consistent with earlier obtained data that the initial value of the culling rate can be use as a longevity predictor (potential) for cows. Concluded that to prolong the productive life of highly productive cows, it is necessary to increase the "initial" value of the general resistance, i.e. functional reserves at a young age, including by eliminating adverse abnormalities during embryonic, fetal and postnatal development, by monitoring the physiological condition of animals and using technological influences at a young age that contribute to an increase in the level of overall resistance.
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