Different sigmoidal nonlinear growth models were fitted in the growth data of triple cross (Friesian×Sahiwal×Hariana) breed and double cross (Friesian×Sahiwal) breed at Agra and Dehradun farms which have different climatic conditions. On the basis of minimum RMSE, the Gompertz model was found to be the best fit. The estimates of growth rates and maturity weights of Friesian×Sahiwal×Hariana breed were considered better under homoscedastic and heteroscedastic error conditions at the Agra farm. Similarly, the growth rates and maturity weights of Friesian×Sahiwal breed were better at the Agra farm, as compared to the Dehradun farm. Therefore, it may be concluded that the climate of Agra (plain area) was more suitable for both the breeds for attaining the maturity weight, as compared to Dehradun (hilly area).

The paper is aimed at studying the effect of different climates on the growth of crossbred cattle. For this purpose, two cattle farms, in Agra and Dehradun, were selected. The two stations have quite different climates due to their geographical location on Indian map. In Agra, the weather and climate are extreme and tropical. The summers are extremely hot and the maximum temperature goes as high as 45 °C, while the weather during winter remains cold and foggy at times. During the monsoon season, Agra city receives heavy rains and the weather becomes hot and humid. The overall climate of Agra can be summed up as extreme, i.e., mercury rises too high in summers, and during the winter months of December-January, the weather becomes cold. The average elevation of Agra is 554 ft above sea level.

In contrast, the climate of Dehradun is moderate due to its location at the foot of the Himalayas. The climate of Dehradun also depends upon the altitude; the higher you go, the colder you feel. Summer temperatures do not go too high, though in winter, the temperature sometimes falls below the freezing point. During summers, the temperature ranges between 36 °C and 16.7 °C. In winters, the temperature lies between 23.4 °C and 5.2 °C. The average elevation of Dehradun is 2,241 feet above sea level.

Growth studies are very important for livestock production because growth is the foundation on which associated products, such as milk, meat and wool rest. Growth models are used to predict growth rates and change in the shape of the organism. In general, the growth data of animals is nonlinear in nature, therefore nonlinear growth models are fitted to study the growth of various animals. Various forms of nonlinear models were attempted for establishing the body weight and age relationship, and the most suitable growth model was finally selected on the basis of known statistical criteria. Brown et al. (1972) compared different nonlinear models for weight-age data in cattle under homoscedasticity. Brown et al. (1976) and Kolluru et al. (2003) studied nonlinear growth models for cattle. Lambe et al. (2006) also studied different growth models in the case of lamb.

In this paper, a comparison of the performance of different breeds maintained at different farms in different climatic regions was made using nonlinear growth models under homoscedastic and heteroscedastic error conditions for the same breed.

Genetics & Evolution Journal, CEL-I Endonuclease, Heterozygous Mutants, Homozygous Mutants, Biological Processes, Plant Mutants, Solanum Lycopersicon, Microcentrifuge Tubes, Homozygous Plants, Plant Genes, Cross Pollination, Heteroduplex Formation.