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 develop the basic elements of the system for predicting the lifetime productivity of cows, taking into account the dynamics of the herd turnover. The idea of constitutive resistance (CR) is used as an age-dependent background steadiness of the body's systems to the action of risk factors. The initial level of the CR is largely determined genetically, but it may also depend on the epigenetic effects, manifested in the pre- and postnatal life. With the aim to predict the productive longevity of cows, two types of positive relationships can now be used: 1) the level of the CR on the first lactation (potential of viability, PV) − productive longevity, and 2) viability, estimated by culling risk on the first lactation − the length of productive life. Results of the analysis suggest that the main factors determining the cows lifetime milk yield are potential of productivity (PP) and potential of viability. The mean group levels of these factors can be determined currently by indirect features − according to milk yield records and to culling risk on the first lactation. Age dynamics of 305-days milk yield in groups with different productive longevity is determined by a combination of gradations PP and PV. Estimates of genetic PP on the highest lactation will always be shifted off due to "down" influence of viability factor on the degree of realization of the lactation activities potential. To predict the economic efficiency of milk production, taking into account the dynamics of herd turnover, it would be advisable to use the value of the length of effective productive life (excluding the contribution of milk yield of cows with highest longevity on the level 1-2%). This quantity is approximately twice the average length of productive life. As the length of productive life does increase, the magnitude of the profit on milk output increases, and in the presence of a pronounced inverse relationship between RA and RV, reaches its maximum when the average length of productive life is 3.5-4 lactation with subsequent reduction.
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