The effect of litter size and sward height on ewe and lamb performance

Abstract

This study compared ewe and lamb performance in twin-and triplet-bearing/rearing ewes offered varying sward heights from day 64 (P64) of pregnancy until weaning at day 87 (L87) of lactation. Ninety-six twin-and 90 triplet-bearing Romney ewes were randomly assigned on P64 to four replicated sward height treatments (2, 4, 6, and 8 cm sward height). Within 24-36 h of parturition (L1) the ewes were reassigned to two (4 and 8 cm) replicated sward heights until weaning at L87. Ewes grazing the 2 cm sward height during pregnancy were significantly (P < 0.01) lighter at P99 and P132 and at L1 than ewes grazing 4, 6 or 8 cm swards. These ewes also had significantly (P < 0.01) lower dry matter intakes, condition scores, and ultrasonic backfat depths. Litter size had no effect on ewe intake, ewe liveweight or condition score throughout pregnancy and lactation. Ewes grazing the 2 cm sward height had significantly (P < 0.05) lower dry matter intakes during pregnancy than ewes on the 4, 6, and 8 cm treatments. Estimated herbage dry matter intakes measured using n-alkanes were similar to calculated energy requirements. Lambs born to ewes grazing the 2 cm swards during pregnancy were lightest at birth (P < 0.01), but sward height during pregnancy or lactation had no effect on lamb weaning weight or lamb survival rate to weaning. Tripletborn lambs were 0.9 kg lighter (P < 0.05) than twins at birth, with the difference increasing in those lambs reared as a full triplet set to 4.7 kg at L87. Lamb losses were 14% in twin-born lambs and 32% in triplet-born lambs. There was no sward height by litter size interaction for ewe liveweight, intake or lamb birth and weaning weight or survival, therefore the results suggest ewes rearing either twins or triplets should be fed sward height allowances of 4 cm or better during pregnancy. However, there is no need to feed above 4 cm in pregnancy or lactation to optimise lamb weaning weight, lamb survival or ewe liveweight and condition score gain.

Trend analysis of plasma insulin level around parturition in relation to parity in Saanen goats1

“…This was possibly due to the fact that in the multiparous group there was a greater number of goats that gave birth to triplets of kids in comparison to the primiparous group. A positive relationship between plasma NEFA and litter size was observed in ewes and goats (Morris and Kenyon, 2004;Laporte-Broux et al, 2011). In the present study, plasma NEFA concentration and litter size were positively correlated on the day of parturition.…”

The effect of ewe size and nutritional regimen beginning in early pregnancy on ewe and lamb performance to weaning

“…interestingly, there was a tendency for higher NEFA and β-hydroxybutyrate concentrations in mid to late pregnancy in the ad lib ewes compared to their Maintenance fed counterparts. Higher concentrations of these metabolites are observed under conditions of less than optimal nutrition (Morris & Kenyon 2004). However, given the relatively poor body condition scores, a subjective measure of level of adiposity, of the Maintenance fed ewes in late pregnancy it is possible that they had few body reserves to utilise, explaining the lower NEFa and β-hydroxybutyrate concentrations observed in this group.…”

“…The "Ad lib" nutritional regimen aim was to provide ad lib grazing conditions. Morris & Kenyon (2004) have previously shown that ewe intakes do not differ above a minimum cover of approximately 1200 kg DM/ha. Therefore, from P21 until P140, the four treatment groups included; large-ad lib (n = 151), large-Maintenance (n = 153), Small-ad lib (n = 155) and Small-Maintenance (n = 153), all of which contained singleton-and twin-bearing ewes.…”

“…Ewe plasma glucose, β-hydroxybutyrate and nonesterified fatty acids (NEFa) concentrations are known to be affected by ewe nutrition and pregnancy rank (Morris & Kenyon 2004). Therefore, 86 ewes, including ewes from within each ewe size and nutritional regimen, were randomly selected and blood sampled (10 ml) via jugular venepuncture (Heparin, Becton Dickinson Vacutainer Systems, USa) on days P23, P64, P100 and P140.…”

Does early pregnancy nutrition affect the performance of triplet-bearing ewes and their progeny to weaning?

“…The effects of differing herbage or concentrate feeding levels in mid and late pregnancy on triplet-bearing ewes and their offspring's performance has been examined in several studies (Everts 1990;Kleemann et al 1993;Hinch et al 1996;Morris & Kenyon 2004;Kenyon et al 2005Kenyon et al , 2010aKenyon et al , 2010bEverett-Hincks et al 2005;Corner et al 2008, Corner et al 2010Kerslake 2009Kerslake , 2010. Under pasture-based conditions, under-nutrition in mid to late pregnancy can result in reduced ewe liveweight, ewe body condition and lamb liveweight (Morris & Kenyon 2004;Corner et al 2008), poorer ewe and lamb behaviour post-birth (Everett-Hincks et al 2005;Corner et al 2010) and reduced indices of colostrum uptake .…”