Abstract

Serial measurements of udder volume in 11 multiparous and 4 primiparous Jersey cows in mid-lactation were used to establish the time of cessation of milk production after a period of milk accumulation. Udder volume was determined from measurements of udder height, length and width. Functional udder capacity (defined as the litres of contained milk in the udder when milk secretion ceased) was greater in cows (15.5 ¦ 0.8 litres) than heifers (9.3 ¦ 0.7 litres). Expressed as hours-worth of secretion, on average, heifers possessed 25.9 ¦ 1.5 and cows 33.6 ¦ 2.9 hours-worth of capacity - data which indicate some potential for reduction in milking frequency without loss of production. Functional udder capacity (l.) was correlated with empty udder volume (tissue volume), and was greater in cows showing high residual milk volumes. The data show that once functional capacity is reached the shut down in milk secretion is rapid, occurring over a 2-4 h period, the rate of accumulation of secretion being constant up to this time.