NATTAPHON CHONGKASIKIT1, THERDCHAI VEARASILP1, KESINEE GATPHAYAK1, JOHN DAVID KABASA2
1Chiang Mai University, Department of Animal Science, Thailand
2Georg-August-Universität Göttingen, Institute of Animal Physiology and Animal Nutrition, Germany
In dairy farming, environmental differences influence performance significantly especially between the temperate and tropical countries. The question of a possible genotype-environment interaction between these two completely different production environments thus arises. In the tropics, there are more differences in dairy cattle performance because the climatic variability between seasons and years is more. In Thailand, a tropical country with three different seasons, climatic and weather differences between seasons and years are immense. This might affect productive and reproductive traits of cows that calve during the different seasons and years. The objective of this study was to determine the effect of calving season and calving years on productive and reproductive traits.
The results revealed no significant effects of calving season and calving years on milk yield at 100 days, milk yield at 305 days, % protein, % fat, % lactose, total solid and solid not fat. However, a clear interaction between calving season and calving years on milk yield at 100 days and milk yield at 305 days was observed. During the rainy season, days open and days of heat return were higher (p < 0.05) than in the winter and summer season. During winter, service per conception was lower (p < 0.05) than in the rainy and summer season. Meanwhile, in summer, the calving interval was higher (p < 0.05) than in the rainy and winter season. For the calving years, no effects on days open, gestation length, days of heat return after calving and calving interval could be observed. However calving years affected the service per conception.
Keywords: Environmental effect, productive traits, reproductive traits