Production of ewes rearing twin or triplet lambs fed grass silage with a commercial concentrate or a mixture of beet pulp and soybean meal

Abstract

Forty multiparous Outaouais ewes were used to investigate the effects of number of suckling lambs (2 versus 3) and type of feed supplement in grass silage-based diets on ewe and lamb performance. Treatments were arranged in a 2 × 2 factorial design. Isonitrogenous and isoenergetic supplements were either a mixture of beet pulp and soybean meal (BP) or a commercial concentrate (CO). Dietary treatments continued from 28 d prepartum until 42 d postpartum. Milk yield was measured weekly. Dietary treatments and number of suckling lambs had no effect (P > 0.10) on DM intake. Feeding BP resulted in similar milk yield for ewes nursing twin (TW) and triplet (TR) lambs, and feeding CO resulted in higher milk yield for ewes nursing TW compared to those nursing TR; this resulted in a significant interaction (P = 0.08) between diet and the number of suckling lambs. Dietary treatments and number of suckling lambs had no effect (P > 0.10) on milk composition. Loss of body weight was greater (P < 0.01) for ewes nursing TR than for those nursing TW, while there was no difference (P > 0.10) between ewes fed BP and those fed CO. Body weight at birth and on day 42, and ADG of TW were greater (P < 0.01) than those of TR, but type of supplement had no effect on lamb performance. Intake of DM was below requirements of ewes nursing TW. These data suggest that DM intake is not responsible for all differences observed in milk yield. Factors such as greater body weight loss could have contributed to increased milk yield. Feeding BP compared to CO may have contributed to maintain similar milk yield for ewes nursing TW and TR, but lamb growth was limited by milk yield as less milk was available per lamb for TR compared to TW. Key words: Ewes, lambs, lactation, beet pulp