Effects of calf separation and injection of oxytocin on milk performance and milk composition of the Polish Red cows
Abstract. The aim of this study was to analyse the yield and composition of milk from Polish Red cattle after 12-hour isolation of calves. Sixty six Polish Red cows were kept together with calves. Control milkings were carried out once a month after 12-hour isolation of calves. Five subsequent milkings after calving were taken under consideration. In the season (May–July 2012) oxytocin (OXT, 1 ml, 3 min before control milking) was injected. The milk of cows milked mechanically after 12-hour isolation of calves was characterized by a very low fat content (0.47–0.58 %) depending on the month after calving. There were no differences in protein and lactose content compared to the standard composition of cow’s milk. The milk yield was 6.16 kg in the first milking after calving and 3.55–4.01 kg in the four further milkings. After administration of OXT a significant increase of milk was observed in the first (12.9 kg) and subsequent months of lactation (8.5–12.4 kg). Milk fat content was significantly higher (4.14 % in the first and 3.39–3.86 % in the further milkings).