Welfare of dairy cattle in conditions of global climate change

Abstract

. This review of literature sources is devoted to the problem of the influance of climate change on dairy husbandry, as well as approaches to welfare evaluation of the animals and the search for reliable markers of the functional state of the body in conditions of high temperatures. Global climatic changes connected with rising temperatures and fluctuations in weather conditions have the influence on agrarian production in general and dairy husbandry in particular. Decrease of yield capacity and food value of plants as a natural source of forage for animal husbandry, favorable conditions for the development and spread of pathogenic microorganisms, as well as the direct action of extreme high temperatures on health, productivity and reproductive capacity of animals, cause significant economic losses in hot periods of the year, not only for tropical regions of the world, but also for most European countries. Today, among the immediate environmental tasks, priority in the context of global food security is the use of urgent measures and the search for long-term (perspective) strategies to prevent the possible consequences of climate change. It is known that horned cattle, especially highly productive horned cattles, are better tolerate to lower temperatures than high, because their thermoneutral zone, in most reports, is in the range from +5 to +20–25°С. The animals, are being present in an artificial, limited space of premises, unable to show the whole range of natural behavioral reactions, and therefore the level of their welfare depends entirely on the conditions created by man. Under such circumstances, monitoring of the air environment and its direct influence on the physiological state of dairy cattle is better done by calculating special indices that take into account several environmental parameters (temperature, relative humidity, air velocity), which act on the organism of animals in a dynamic complex. However, such indices have not been sufficiently disseminated among domestic researchers. Although for more than half a century, the most commonly used in the world practice for evaluation the comfort of animals during periods of heat, is a temperature-humidity index. It is convenient in calculation and informative enough. Numerous studies indicate a close relationship between temperature-humidity index and animal body temperature, respiratory rate and heart rate, which are widely used to elevation the clinical conditions during thermal stress. The relatively high correlation between temperature-humidity index and productivity (milk yield and content of its components) allows using this index in prognostic models of influence of environmental on the dairy cattle. A various biological markers of the functional state of animals deserve attention. The possibility using such markers as predictors of the effects of high temperatures on the welfare of animals is reported in the proposed literary review.