INFLUENCE OF MILKING 3 TIMES A DAY ON MILK QUALITY

Lactations were divided into three periods: early (1 to 99 d), mid (10 0 to 199 d), and late (200 to 299 d). One hundred Holsteins were rando mly split into four groups that were balanced for parity. Groups 222 a nd 333 were milked twice and three times a day, respectively, througho ut lactation. Group 233 was switched from twice to three times daily m ilking at 100 d, and group 223 was switched at 200 d. Compared with gr oup 222, milk yield for group 333 increased by 10.4%, and fat and prot ein yields increased by 4.7 and 7.3%, respectively. Mean milk SCC for all groups was <175,000 cells/ml within each lactation period. The per centage of CP was lower for cows milked three times a day than for cow s milked twice a day during each stage of lactation (early, 2.78 and 2 .91; mid, 3.08 and 3.19; and late, 3.16 and 3.28, respectively). Casei n as a percentage of CP was significantly higher for cows milked three times a day during midlactation. The acid degree values (milliequival ents of FFA/ 100 g of fat) were significantly higher for milk from cow s milked three times a day than for cows milked twice a day during ear ly and midlactation, (early, 0.75 and 0.55; mid, 0.82 and 0.61; and la te, 0.88 and 0.75, respectively). No differences were detected in milk flavor or plasmin activity because of milking frequency. Casein as a percentage of CP decreased, and plasmin activity increased, as parity and stage of lactation increased.