Changes in body water and solids contents in native and crossbreed growing calves during winter and hot summer seasons of Egypt

The objective of this study is studying the effect of genetic crossing on body water and body solids in growing calves under winter or summer season in Egypt. Twenty calves including 10 native calves and 10 F1 calves (♀ Egyptian cow × ♂ Holstein) were used through two experiments. The first experiment was conducted during winter season on ten calves including 5 native and 5 F1 calves with average 5-6 months of age. The second experiment was conducted during summer season on another ten calves with the same age and body weight including 5 native calves and 5 F1 calves. Results showed that summer season induced significant decreases in live body weight (LBW) by 27.2 kg in native and by 32.9 kg in F1 through 3 months and F1 calves were better than native calves by 23.2 kg and 17.5 kg under winter and summer seasons, respectively. Total body water (TBW) as percentage of LBW values increased significantly and total body solids (TBS) as absolute values through three months decreased significantly by 6.9 kg in native calves and by 9.0 kg in F1 calves due to exposure calves to summer season. Daily gain (BG) and daily solids gain (SG) decreased significantly due to exposure calves to summer season and F1 calves were better than native calves in live BG as well as in SG. The best values in gain were in F1 calves under winter condition and the worsted values were in native calves under summer season.