Influence of weaning age, management, and slaughter age on export lamb carcass production and slipe wool weights

Abstract

A series of five experiments was conducted over a period of 4 years with lambs weaned at 4,5,6,9, 12, 15, or 18 weeks of age. Management treatments included restricted milk intake, creep grazing, rotational grazing, and set stocking. Slaughter ages ranged from 12 to 30 weeks. Early weaning at 4,5, or 6 weeks caused varying post-weaning growth checks, lasting from I to 4 weeks, the most severe following 4-week weaning in the absence of creep grazing. Subsequent growth rates were similar to those for later-weaned lambs. Weaning lambs at 9 weeks of age resulted in similar final live weights to those obtained by weaning at 12 or 15 weeks. The reductions in final slaughter weights caused by early weaning (up to 21%) were associated in some experiments with lower killing-out percentages and reduced carcass fat. In one experiment, where treatments were compared at a common carcass weight of 17.5 kg, 4-week weaning resulted in 2-5% lower levels of chemical carcass fat and up to 4% and I % higher values for water and protein respectively than in later-weaned lambs. Creep grazing in association with early weaning tended to minimise the growth check. Restricted milk intake before weaning at 5 weeks of age caused a prolonged growth reduction followed by no compensatory growth. Set stocking resulted in heavier weights for both early-and late-weaned lambs. A liberal supply of milk and grass before early weaning and the lack of subsequent compensatory growth are discussed. Favourable reasons for early weaning include reduction of carcass fat and removal of competition by ewes under conditions of feed shortage. The practice can also be used in association with sheep dairy production, accelerated lambing, or progeny test programmes. It is recommended that the conventional lamb weaning age be reduced to about 9 weeks.

Effect of weaning age on growth rates of lambs infected by gastrointestinal parasites

“…Early weaning was used as a tool to investigate the effect of gastrointestinal parasites on young lambs with and without milk intake. Early weaning had a major impact on performance of young, light animals as found in earlier studies (Rattray et al 1976;Geenty 1980) but little or no effect on heavier lambs weaned on good quality forage. Lambs failed to compensate for the significant early setbacks from lack of milk within the duration of either study and any later compensation will be limited (Bray et al 1990).…”

Forward creep grazing of lambs to increase liveweight gain and post‐weaning resistance to endoparasites

“…This could potentially further increase lamb performance, especially from those reared as multiples. Furthermore, this would reduce the inefficient use of quality pasture by ewes and reduce the post-weaning check to lamb liveweights described by Geenty (1980).…”

Destete artificial en ovinos: respuesta de estrés y bienestar animal. Revisión

“…Los mismos autores observaron los mismos cambios de comportamiento, y una menor tasa de crecimiento de los corderos cuando el destete se realizó a las 13 que a las 16 semanas (46) . El efecto de la edad al destete sobre el crecimiento de los corderos ha sido ampliamente estudiado (44,45,47,48) . De manera general lo que vocalizations are greater after weaning lambs at 2 than at 4 mo (6) .…”

“…The effect of age at weaning on the growth of the lambs has been widely studied (44,45,47,48) . In general, the rate of growth is more affected when weaning is performed earlier, which is probably due to a slower adaptation to solid food intake in younger lambs (49) .…”