Wool growth of pregnant and lactating Merino ewes

Abstract

The wool production of pregnant, lactating and non-pregnant, non-lactating (dry) Merino ewes eating one of three diets: chaffed oaten hay (OH), chaffed lucerne hay (LH), and a 50/50 (w/w) mixture of OH and LH, was determined. Measurements were made for 2 months prior to mating, during pregnancy and for 3 months after lambing, and for the dry ewes over the same period.Production of clean wool (Y, g/day) by dry ewes was linearly related to digestible organic matter intake (X, g/day): Y = 00301X-3-34, r = 0-97. Clean wool growth was significantly less (P < 0-01) than dry ewes in the 4th and 5th month of pregnancy and throughout lactation. During pregnancy the total deficit in clean wool growth (calculated as the difference between observed wool growth and that expected on the basis of the relationship between feed intake and clean wool growth of dry ewes) was 456 g for ewes bearing a single lamb and 578 g for those bearing twins, with no difference between diets. In lactation the total clean wool growth deficit increased as milk production increased, and for every litre of milk produced there was a deficit of 12 g clean wool.Wool fibre diameter was reduced during the 1st month of lactation. There was no consistent effect of pregnancy or lactation on the number of wool follicles per mm 2 , the ratio of primary plus secondary to primary wool follicles, or on the thickness of skin on the midside.Digestibility of dietary organic matter (DOM) was reduced during the last 3 months of pregnancy, and the first 2 months of lactation. However, this was insufficient to account for the magnitude of the decrease in wool growth seen during pregnancy and lactation.Wool sulphur content increased during pregnancy (P < 0-001), but not during lactation. The relationship between total plasma cyst(e)ine concentration and DOM intake during pregnancy was similar to that in dry ewes, but during lactation total plasma cyst(e)ine concentration was less than expected. It was calculated that during pregnancy the amount of sulphur saved through reduced wool growth was greater than that deposited in the conceptus, and during lactation the amount of sulphur saved in reduced wool growth matched that excreted as milk.These results are discussed in relation to control of wool growth during pregnancy and lactation. a n d a P P e a r s t o b e dependent on the quantity and quality of feed available (Corbett & Furnival, 1976). Annual wool growth in Merino ewes is decreased In different strains of Merino ewes the effects of from 7 to 26 % as a result of bearing and rearing pregnancy and lactation can be quite different lambs (Corbett, 1979).

Effects of pasture allowance in winter on liveweight, wool growth, and wool characteristics of Romney ewes

“…The differences in wool growth between the pregnancy categories were consistent across allowances, as found by Oddy (1985). Oddy calculated the reduction in the wool growth of single and twin-bearing ewes from the wool growth/feed intake regression for dry ewes and found that this did not change significantly over a wide range of feed intake and wool growth values.…”

On-farm factors affecting physical quality of Merino wool. 1. Nutrition, reproduction, health and management

“…As a result, while dry matter intake increases during pregnancy and lactation, the efficiency with which dry matter is turned into wool decreases (SCA, 1990). With the same nutrition, ewes that lamb in a given year produce approximately 0.4-0.5 kg less CFW than dry ewes, with the deficit being higher for twin bearing ewes (Oddy, 1985;Waters et al, 2000;Lee et al, 2009). FD tends to decrease along with reduced wool growth (Lee and Atkins, 1995) although Lee et al (2009) found that it varied little between flocks of ewes which differed in reproduction rate by as much as 1 lamb/ewe/year.…”

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

“…The adverse influence of the stress of reproduction on fibre traits is well-documented (Turner et al, 1968;Corbett, 1979;Oddy, 1985;Charlick & Arnold, 1990). The clean wool production of ewes shorn prior to lambing was increased (P < 0.05) compared to contemporaries shorn prior to joining.…”