Energy supplementation of silage for ewes in late pregnancy

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Abstract
SUMMARY: 1. Four groups of 20 ewes were individually fed in late pregnancy on: (1) silage ad libitum, (2) silage ad libitum and 12 kg rolled barley, (3) silage ad libitum and 23 kg rolled barley, (4) pelleted milled dried grass ad libitum. The concentrate was offered on a rising plane over the last 6 weeks of pregnancy. After parturition the ewes and lambs were put on spring pasture.2. The intake of silage by twin-bearing ewes fell slightly but nonsignificantly during week 16 of pregnancy but thereafter remained steady up to lambing. There was no other decline in intake on any of the treatments. Barley, however, significantly depressed silage intake when the quantity was increased above 282 g per day.3. Single-bearing ewes, except those on treatment 1, gained in net body weight during late pregnancy. Twin-bearing ewes on treatment 4 gained in net body weight while those on the other treatments lost weight.4. Birth weights of single lambs from ewes on treatment 1 were significantly lower than those from treatment 3. This was the only significant difference in birth weight or subsequent growth rates of single lambs. Birth weights of twin lambs on treatment 1 were significantly lower than those on the other treatments.5. The birth weight of twin lambs appeared to be an important determinant of subsequent performance, and may thus be a valuable criterion of the adequacy of the ewe's diet in late pregnancy.6. With medium-quality autumn silages, 12 kg of barley given during late pregnancy is sufficient to ensure good reproductive performance in ewes.