EFFECTS OF FEEDING METHODS, SEASON AND PRODUCTION LEVEL ON LACTATION PERFORMANCE AND FEEDING BEHAVIOUR OF DAIRY COWS

摘要

The present study was conducted to investigate the effects of feeding methods, season and production level on lactational performance and feeding behaviour of dairy cows. Twenty Holstein Friesian cows having 513 kg liveweight, 140 DIM, 25 kg milk/d for summer and the same number of cows having 543 kg live weight, 121 DIM, and 28 kg/d for winter were allocated 4 experimental groups consisting of 2 feeding methods (single feeding and choice feeding) and 2 production levels(low:~21 kg/d and high:~29 kg/d) combinations in a factorial arrangement. Single diet(TMR) was formulated with barley, corn, soybean meal, corn gluten meal, wheat bran and alfalfa hay grounded in 1.5-2 cm size with 60/40 concentrate/roughage ratio. These feed ingredients were offeredto choice-fed cows ad libitum seperately and simultaneously. Choice-fed cows made diets containing less alfalfa hay and corn, and more barley than those fed single diet. High yielding cows preferred more barley than those of TMR compared to low yieldingcows. Choice fed cows had lower dry matter intake and fat corrected milk than those fed with single diet. Nutrient intakes were lower for choice fed cows than those fed with TMR due to lower feed intake. Milk fat and milk urea level were lower for choice fed cows than those fed TMR. Milk protein contents were decreased as milk production increased. Season affected significantly milk yield, feed intake (as a percentage of body weight), milk yield & live weight changes and 4% FCM yield. These changes influenced the intakes of dry matter and nutrients, eating patterns and, consequently, the nutrient requirements of dairy cows in both production levels and seasons. The results revealed that choice fed cows changed their diet selection according to the changed season and milk yield but this did not affect milk yield positively.