Pasture management to minimise the detrimental effects of pre‐lamb shearing

Abstract

The purpose of this study was to examine whether the performance of pre-lamb shorn sheep is influenced by pasture allowance in the immediate post-shearing period and whether the relationship between performance and pasture allowance differs according to whether the ewes are shorn by standard comb or cover comb. The trial was replicated across two years to allow for climatic variations between years. Fifty-four ewes were used in each year in a 3 × 3 × 2 factorial design with three shearing treatments (standard comb, cover comb, and unshorn), three sward surface height (SSH) treatments (nominal 3, 5, and 7 cm), and two pregnancy status treatments (single and twin). Rectal temperatures of standard comb or cover comb ewes were significantly lower (P < 0.05) than those of unshorn ewes on day 2 following shearing (S2), and on S4, S8, and S20. Pasture allowance, however, did not affect rectal temperatures of shorn ewes. There was an interaction (P < 0.05) between shearing treatment and SSH. Thus, liveweight gains during the period from pregnancy day 115 (P115) to P135 were 275, 613, and 4518 g; 1557, 2314, and 3997 g; and *Author for correspondence 3623, 2894, and 3997 g for standard comb, cover comb, and unshorn (control) ewes set-stocked on 3, 5, and 7 cm SSH, respectively. There was no interaction between shearing treatment and SSH for lamb birth weight, but the birth weights of lambs born to standard comb ewes (4.9 ± 0.1 kg) were significantly greater (P < 0.05) than those of lambs born to unshorn ewes (4.3 ±0.1 kg). There were no effects of shearing treatment or SSH on lamb weaning weight, ewe wool growth rate or mean fibre diameter. Likewise, there were no effects of shearing treatment or SSH on ewe organic matter intake (OMI), except on the second day following shearing when the OMIs of ewes set-stocked on 3 cm (941 ± 147 g) were significantly (P < 0.05) lower than those of ewes grazing 5 cm (1628 ±101 g) or 7 cm (1349 ± 135 g) SSH pasture. The results suggest that hypothermia, as determined by rectal temperatures and induced by pre-lamb shearing, cannot be avoided by pasture management, provided SSH exceeds 3 cm. This reflects the fact that, in the period immediately after shearing, ewes do not increase feed intake when provided with increased pasture allowances.

The effects of shade and shearing date on the production of Merino sheep in the Swartland region of South Africa

“…Although smaller responses have been observed under pasture conditions in a temperate climate (i.e. Cloete et al, 1994), the majority of literature sources found no improvements in growth or weaning weight under pastoral conditions (Dabiri et al, 1994;1995;Cloete & Durand, 1996;Husain et al, 1997). From these references it appears as if growth responses in the progeny of ewes shorn prior to lambing are transient and unpredictable, although they may occasionally be present.…”

“…Results of studies conducted under free-ranging conditions in temperate areas are much less consistent. Birth weight responses are variable under these conditions (Dabiri et al, 1995;Husain et al, 1997). In a recent study, Kenyon et al (1999) not only found that responses in birth weight varied under outdoor conditions, but also that the realized response in groups shorn prior to lambing could be related to the mean birth weight of the control group.…”

“…It was concluded that the response in birth weight to pre-lambing shearing may be maximized under conditions where maternal constraints limit fetal growth in unshorn ewes. The practice of shearing prior to lambing is seen as a means of enhancing lamb survival (Kenyon et al, 1999), but variable results have been reported (Alexander et al, 1980;Irazogui & Giglioli, 1984;Husain et al, 1997).…”

Environmental controls on lambing rate in Patagonia (Argentina): A regional approach

“…Both factors are known to affect the ELR by increasing lamb mortality (Olaechea et al, 1981;Bellati and von Thu¨ngen, 1988;Coronato, 1999). Management practices, such as stocking rate, mating time, supplementary feeding and shearing time, are also known to affect ELR (Rattray and Jagusch, 1978;Husain et al, 1997;Golluscio et al, 1998b). There are also methodological constraints that could account for the unexplained residual.…”

Returns to investment in on‐farm research: A case study of cover comb technology

“…The IRR is the discount rate at which the net present value is 0 (Gittinger 1982 (Table 1). Direct costs for the trials were based on the budgets submitted in the research proposals, the "Materials and Methods" sections of related publications Holmes et al 1992;Dabiri et al 1995aDabiri et al , 1995bBurnham et al 1996;Husain et al 1997), and personal communication with the authors of these papers. The labour contribution by postgraduate students was costed at technician rates to fully reflect the cost of the research.…”