CISTERNAL MILK IN THE DAIRY-COW DURING LACTATION AND AFTER PRECEDING TEAT STIMULATION

Experiments were designed to determine the cisternal milk during machi ne milking in unfamiliar surroundings, which has previously been shown to inhibit milking-related oxytocin (OT) release and milk ejection. T he first experiment was performed with 22 cows in early, mid and late lactation. After cisternal milli. was removed, 10 i.u. OT were twice i njected intravenously to remove the remaining milk. Total milk yield, cisternal milk yield, cisternal milk fraction (17 and 12% in early and late lactation) and the milk yield obtained in response to the first OT injection significantly decreased from early to late lactation. Cis ternal milk yield was similar in front and rear udder halves. However, owing to higher total yield, the cisternal milk fraction was lower in rear than in front halves. Cisternal milk yield and cisternal milk fr action were smaller in primiparous than in older cows. In a further ex periment milk distribution in the bovine udder was evaluated after pre ceding teat stimulation and milk ejection. Teats of 12 cows were manua lly stimulated for 1 min at 15, 60 or 120 min before milking. Total mi lk yield was not significantly different with or without teat stimulat ion. However, cisternal milk yield and fraction were significantly hig her in teat stimulated cows than in unstimulated controls but were sim ilar whether cows were stimulated 15, 60 or 120 min before milking.