Seasonal effects on milk yield, erythrocytic and leukocytic indices of Kankrej cattle (Bos indicus)

Materials and Methods Mammals, including ruminants, exhibit seasonal rhythms of physiological functions to cope with climatic fluctuations in order to establish equilibrium [1]. The seasonal rhythms reflect the ability of endogenous adaptive mechanism of animals to react in advance to environmental changes associated with seasons [2]. In fact, physiological equilibrium is maintained by blood and hence every change that takes place in mammalian body is reflected in the blood indices [3]. Thus, blood profile reflects physiological responsiveness of animals to its internal and external environments [4] and form the very basis for diagnosis, treatment and prognosis of many diseases [5]. Further, it is also an important tool to assess the level of stress due to various environmental stressors and nutritional factors [6]. The environmental stressors in turn vary from season to season.According to bio-climatological variables, the climate of Gujarat, India falls under semi arid zone coupled with hot and humid condition, which itself poses as harsh abiotic factor for optimum productivity of livestock. Nonetheless, Kankrej ( ), a native cattle breed of the state, is known for yielding good quantity of milk with high fat content even in these extreme climatic conditions. The breed is being maintained as elite herd at Livestock Research Station (LRS), SDAU), Sardarkrushinagar and proved to be superior to crossbreds and other native breeds with respect to milk production and disease resistance [7]. Surprisingly, the milk yield of this breed has been observed to be increased over the last five years during summer, though no scientific report has been made in this aspect. It is universal that the maintenance of productivity of an animal is essentially a function of environment, since genetic potentials cannot be expressed unless a congenial environment is provided [8]. Therefore, proper understanding of how climatic factors affect the physiological response of animals provides a firm basis of improving the husbandry practices. In the light of above discussed features, the present investigation was planned to assess the seasonal influence on milk production and haematological indices of Kankrej cattle between different production groups.