Growth of sheep to the age of three years after a severe nutritional check in early post-natal life

Abstract

At Mount Derrimut Field Station from 1982 to 1985, growth and body composition was studied in three groups of wethers from the same flock. A control group (C) and a restricted group (R) were housed from the age of 1 day until slaughtered. The first slaughter was at the age of c. 1 year (reported elsewhere) and the second at the age of c. 3 years. Apart from the first 36 days, when group R was fed a severely restricted ration, both groups were fed a high quality diet ad libitum throughout the experiment. At the end of the second year, a group of 2-year-old wethers (G) was introduced, to compare the growth of these sheep with those in groups C and R. Group G sheep were reared on their dams, kept as grazing animals and killed at the second slaughter.At the age of c. 3 years there was no significant difference between groups C and R for mean fleecefree body weights, but the sheep in group G were significantly lighter (P 0n01) in spite of reaching mature size for grazing sheep in the general flock.After the age of 7 months there was no significant difference between groups C and R in rate of wool production. Rate of wool production in group G sheep was not significantly different from that of sheep in the other groups except during the last 6 months, when they produced significantly less wool (P 0n05).Regression analyses for surface and X-ray measurements against fleece-free body weight (independent variable) showed no differences between groups C and R, except for width of metacarpal (X-ray measurement). In this case, the regression coefficients were different (P 0n01) but, at slaughter, actual bone measurements were the same. Both X-ray measurements and those at dissection showed that the metacarpals of group G were significantly (P 0n05) longer and narrower, and had a narrower cortex, than those in the other two groups (P 0n05).There were no significant differences between groups C and R in mean weight and chemical composition of the parts and tissues examined ; however, the carcass fat content of sheep in group G was significantly less (P 0n01) than in the other two groups. The sheep in group G had higher weights (P 0n01) for the brain, the digestive tract (DT), kidneys and liver than those in groups C and R.Cell size in the semitendinosus muscle, as indicated by the protein : DNA ratio, increased (P 0n01) between the first and second slaughters. There were no differences between groups in protein : DNA ratios, but the DNA and protein contents were significantly higher (P 0n05) in the kidneys and liver in group G than in the other groups. Although the weights of the semitendinosus muscle were heavier (P 0n01) in groups C and R than in group G, on a fat-free basis, there were no significant differences between treatments in muscle weight or in DNA and protein contents.It is concluded that sheep will make a complete recovery after a severe nutritional check in early post-natal life if given the opportunity to do so. Even though large differences in body weight may develop between sheep, this appears to have little e...

Efeitos das restrições pré e pós-natal sobre o crescimento e o desempenho de cordeiros Santa Inês do nascimento ao desmame

“…A curva de crescimento dos animais deste experimento foi similar àquelas obtidas por Huidobro & Villapadierna (1992) e Krausgrill et al (1997), que verificaram rápido crescimento nas primeiras fases de vida dos cordeiros.…”

Improving the nutrition of Merino ewes during pregnancy and lactation increases weaning weight and survival of progeny but does not affect their mature size

“…This result is perhaps surprising given that feed on offer during lactation was the major factor influencing weaning weight. While the precise reasons for this are unknown, it is likely that developmental processes that impact on mature size are more sensitive to nutritional insult during fetal rather than postnatal life (Greenwood et al 2010), even when early postnatal nutritional restriction of sheep is severe (Krausgrill et al 1997).…”

“…The lightest 20% of Merino weaners within a flock are~3 times more likely to die than those from the middle 20% of weaning weights, and Campbell et al (2009) reported that increasing growth rates from~10 to 20 g/day during the 5 months after weaning reduced the risk of mortality by more than 70%. If restriction of growth of sheep before weaning is severe and prolonged the growth of muscle and bone may be limited (Greenwood et al 1998(Greenwood et al , 2000Tygesen et al 2007) and ultimately mature size may or may not be reduced (Schinckel and Short 1961;Everitt 1967;Krausgrill et al 1997;Kelly et al 2006). Lamb growth to weaning is largely determined by intake of milk (Doney and Peart 1976;Snowder and Glimp 1991) and increasing the dietary energy intake of ewes during lactation increases ewe milk production and lamb growth (Langlands 1977;Jordan and Mayer 1989).…”

Effects of birth weight and postnatal nutrition on neonatal sheep: II. Skeletal muscle growth and development.

“…Furthermore, maternal undernutrition during late pregnancy resulted in lower mature weights of offspring up to 5.5 yr of age (Reardon and Lambourne, 1966;Gunn, 1977). In contrast, severe nutritional restriction of lambs during the first 5 to 6 wk of postnatal life did not impair subsequent growth, including that of muscle, to 4 mo (Tulloh et al, 1986), 12 to 14 mo (Hopkins and Tulloh, 1985), and 3 yr of age (Krausgrill et al, 1997). Similarly, the present study, consistent with the findings of Johns and Bergen (1976), did not find any effect of postnatal nutritional treatment on DNA content of muscle when assessed relative to weight of muscle.…”