EFFECT OF RUMINANT GRADE MENHADEN FISH-MEAL ON REPRODUCTIVE AND PRODUCTIVE PERFORMANCE OF LACTATING DAIRY-COWS

Menhaden fish meal, fed at 0.7 kg/d [2.7% of dietary dry matter (DM)], replaced blood meal and meat and bone meal (2.0% of dietary DM) in th e diet fed at dairy A (n = 341) and replaced blood, meat and bone, and corn gluten meals (3.2% of dietary DM) in the diet fed at dairy B (n = 300). Cows consumed the experimental total mixed diets from similar to 24 to 109 d postpartum. Cows were synchronized for estrus using inj ections of GnRH agonist at 51 d postpartum, PGF(2 alpha) 7 d later, an d artificial insemination at detected estrus. Resynchronization occurr ed using the same program if estrus was not detected. Diet failed to a lter reproductive responses at synchronized artificial insemination. P regnancy rate at 120 d postpartum was not altered by diet at dairy A ( 65.4% vs. 60.2%) but was improved by dietary fish meal at dairy B (31. 9% vs. 41.3%; interaction of dairy and diet). The dynamics of corpus l uteum regression were altered in cows fe fish meal at dairy B. Dietary fish meal did not influence milk production of cows at dairy A but in creased production of milk (2.3 kg/d) and protein (0.1 kg/d) of second parity cows at dairy B. When dietary fish meal was fed to cows at dai ry B, production of milk at and 4% FCM was higher for cows in parity 5 or greater than that for cows in fourth parity.