Production by ewes rearing single or twin lambs: effects of dietary crude protein percentage and supplemental zinc methionine1

Eighty Targhee ewes with single or twin lambs were used to investigate the effects of chelated zinc methionine and level of dietary CP on milk and wool production, DMI, and ewe and lamb BW change. Treatments were arranged as a 2 x 2 x 2 factorial. Dietary treatments started 30 d prepartum and continued until 42 d postpartum. Milk production was estimated at 4, 10, 18, and 28 d postpartum. During gestation, DMI by ewes receiving zinc methionine and the 14.9% CP diet was greater (P < .10) than DMI by ewes not supplemented with zinc methionine and ewes fed the 11.3% CP diet. Ewes fed the 14.9% CP diet tended (P < .14) to gain more BW from 30 d prepartum to 4 d postpartum and lose more BW from 4 to 42 d postpartum than ewes fed the 11.3% CP diet. Ewes fed zinc methionine and the 14.9% CP diet produced more (P < .10) milk on d 28 than their counterparts. Ewes rearing twins produced more (P < .05) milk on d 4, 10, and 18 than ewes rearing single lambs. However, milk production on d 28 was not affected by number of lambs reared (P = .68). Lamb ADG at 28, 42, and 59 d postpartum was greater (P < .05) for both the zinc methionine treatment and the 14.9% CP diet. Zinc methionine (P = .11) and the 14.9% CP diet (P = .02) increased weaning weights by 6 and 9%, respectively. We conclude that both the zinc methionine supplement and the 14.9% CP diet resulted in more persistent milk production. In addition, when ewes and lambs were fed for an average of 42 d during early lactation, a 14.9% CP diet, and to a lesser degree, a chelated zinc methionine supplement, lamb weaning weights were improved.