Using of Logistic Regression in Animal Science

This study was carried out to examine the effects of environmental factors on different growth with Chi-square, G-test and logistic regression analysis after body weights of these growth periods were categorized as binary. Besides, logistic regression was also based on concordant statistics except Chi-square and G-tests as model fit criteria. With respect to three fit criteria, the relationships among categorized birth weight with categorized body weights in 45th, 60th and 75th days were significant (p<0.01). Moreover, the relationship between periods of the lambs born in early March of 2001 year by using logistic regression. The relationships between categorized body weights and categorized birth weight and/or environmental factors were analyzed sex and only categorized body weight in 75th day was significant (p<0.05). It could be said that birth weight, one of environmental factors, improved model fit more than the other factors when considered all model fit criteria in logistic regression.As a result, it can be suggested that in addition to Chi-square and G-tests used for providing relationship between two traits, logistic regression in terms of obtaining from different information will be an alternative analysis in place of variance analysis

Growth Performances of Female and Male Holstein Calves Fed Milk and Milk Replacers

The objective of this study was to compare growth performances of male and female Holstein calves fed milk and milk replacers. A total of 60 Holstein calves were used in the study. Calves were divided into three equal groups. In each group, there were 10 female and 10 male calves. Calves were offered colostrum for 3 days after birth and were weighed at fourth day for the trial. Initial body weights of calves in dietary treatments were statistically similar. The first, second and third groups were fed milk, milk replacer-I (CP 21% and CF 16.5%) and milk replacer-II (CP 24% and CF 18%), respectively. In addition to milk and milk replacers, calves were supplemented with ad libitum concentrate feed and alfalfa. Dietary treatment was significantly effective (P<0.05) on body weight of calves at 60 days of age. In conclusion, growth performances of calves increased with increasing protein content of milk replacer had better than those of calves fed milk replacer containing low-protein. Therefore, during the suckling period, in feeding of Holstein calves, milk or milk replacer containing high-protein should be preferred primarily