Effects of maturity of silage and protein content of concentrates on milk production of ewes rearing twin or triplet lambs

Fifty-one Outaouais Arcott ewes were used to study the effects of silage ma turity, protein level and number of lambs suckled on milk production and la mb growth in a 2 x 2 x 2 factorial design experiment. Ewes were given ad li bitum access to either an early-bloom (EB) or full-bloom (FB) bromegrass si lage supplemented with 725 g d(-1) of a 15 or 21% CP concentrate. Number of lambs suckled were two or three per ewe. During the 6 wk of lactation, ewe s receiving the EB silages consumed more DM (2.07 vs. 1.74 kg d(-1), P < 0. 01), and gained more (1.3 and -2.7 kg, P < 0.05) than ewes fed FB. Ewes tha t raised three lambs had greater silage intake (2.00 vs 1.86 kg d(-1)) and lost more weight during lactation (-2.8 vs. +0.3 kg) than those suckling tw ins. Milk yields of ewes offered the EB and FB silages were 2.42 and 2.28 k g d(-1), respectively (P < 0.05), for the first 4 wk of lactation. Ewes tha t raised three lambs produced less milk (2.25 vs. 2.43 kg d(-1)) than those nursing twins (P < 0.05). Milk fat content (8.2%) was not influenced by tr eatments, whereas milk protein content was higher (P < 0.05) from ewes rece iving the EB silage compared with the FB silage (5.05 vs. 4.76%). At 4 and 6 wk of age, twin lambs were 2.6 kg (9.5 vs. 6.9 kg) and 3.5 kg (12.0 vs. 8 .5 kg) heavier (P < 0.01) than tripler lambs for EB and FB silages, respect ively. However, at the end of thr 6-wk period, ewes nursing triplets weaned 1.3 kg more lambs than did ewes nursing twins (P < 0.05). Lambs from ewes that received the EB silage were 1.1 kg heavier at 6 wk (P < 0.05) than tho se from ewes fed with the FB silage. Also, lambs from ewes receiving the 21 % CP concentrate were 1.1 kg heavier at 6 wk (P < 0.05) than the lambs from ewes fed the 15% CP. Litters were heavier at 6 wk with 21% CP concentrate compared with 15% (25.1 vs. 24.1 kg, P < 0.05), and tripler litters were he avier (P < 0.01) than twin with the EB silage. Within litter weight variati on (weight difference between the biggest and the smallest lambs in a litte r) proved to be greater (P < 0.05) with triplets (4.2 kg) than twins (2.2 k g). In conclusion, providing a higher quality silage (lower ADF and higher CP contents) improved ewe feed intake, milli production, lamb growth and li tter weight, while feeding a higher protein concentrate only improved lamb growth with the lower quality silage.