Effect of liveweight and condition score of ewes at mating, and shearing mid-pregnancy, on birthweights and growth rates of twin lambs to weaning

Abstract

Liveweight and condition score of ewes at mating had small positive effects on growth rates to weaning of twin lambs. Shearing mid-pregnancy increased birthweights and weaning weights of twin lambs. To achieve high weaning weights of twin lambs, farmers should ensure ewes attain high liveweights and condition scores at mating and shear mid-pregnancy. It is speculated that the effects of liveweight and condition score of ewes at mating on weaning weights of twin lambs would be greater than those observed in the present study under conditions in which nutrition of the dam is below optimum.

Effect of liveweight and teasing of ewe hoggets prior to breeding on lambing pattern and weight of singleton lambs

“…However, little effect was observed in ewes offered a level of herbage which maintained maternal weight. In contrast, Kenyon et al (2004a) reported a small positive relationship between the weight of ewes at mating and birthweights of twin lambs (0.02 kg/kg liveweight of the dam) under conditions in which the total weight of ewes increased at a level similar to the expected weight of the conceptus at term. Similarly, in the present study liveweight of the hoggets pre-breeding had a small positive effect on singleton lamb birthweights (0.046 kg/kg liveweight of dam) under conditions in which the total weight of hoggets increased at a level similar to the expected weight of the conceptus at term.…”

“…It is known that "fat" mature ewes produce more milk than thin ewes (Rattray 1986) during periods of restricted feeding as their body reserves can be used to support milk production, especially in twin-suckling ewes. Both McCall et al (1986) and Kenyon et al (2004a) reported a positive effect of pre-lambing weight of mature ewes on lamb growth. Similarly, late pregnancy liveweight and body condition of mature ewes has been reported to positively effect growth rates of lambs (Gibb & Treacher 1980;Wilson et al 1985;Hossamo et al 1986).…”

“…However, the effect of hogget liveweight on the birthweight and growth rate of the resulting lamb(s) is unknown. In mature ewes, positive relationships between liveweight and both birthweight and growth rate of lambs have been reported (Gibb & Treacher 1980;Russel et al 1981;Wilson et al 1985;Hossamo et al 1986;McCall et al 1986;Kenyon et al 2004a). If these observed effects were found in hoggets, heavier birthweights of lambs might improve survival and higher growth rates should increase lamb weaning weight.…”

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

“…Lamb growth to weaning is influenced by lamb birth weight and dam milk production (Peart 1967;o'Connor 1996;Muir et al 1998;Kenyon et al 2004a). Milk production itself is affected by ewe pregnancy rank, body condition and liveweight of the ewe and her nutrition in pregnancy, and size of lamb at birth (Peart 1967;Treacher 1970;Rattray 1986;Bencini & Pulina 1997;Muir et al 1998;Bizelis et al 2000).…”

Birth weight effect in twin‐born lambs from mid‐pregnancy shearing is associated with changes in maternal IGF‐I concentration

“…Shearing ewes between days 50 and 100 of pregnancy has been identified as a technique that consistently increases lamb birth weight under pastoral (Kenyon et al 2004;Corner et al 2007) and winter-housed, sheep management systems (Dyrmundsson 1991). This increased birth weight has also been associated with an increase in lamb survival rates to weaning (Morris et al 1999;Kenyon et al 2006).…”