Changes in the body composition and efficiency of mature sheep during loss and regain of live weight

Abstract

The body composition of eight Merino wethers was estimated from the tritiated water (TOH) space and live weight at intervals during a cross-over experiment in which they were fed to either maintain a uniform live weight (about 34 kg) or to lose and, later, recover live weight over a 17-week period. The diet was a pelleted mixture of lucerne and wheat.The multiple regression equations used for these estimates were established from the chemical analysis of 24 sheep, including six from the cross-over experiment, which were killed at intervals during these two feeding regimens. The inclusion of TOH space in addition to live weight in the regression equations decreased the standard error of the estimates of body water, fat and energy by two-thirds. Correction of TOH space and live weight for gut water did not increase the precision of the equations.Sheep which ate, during the first 4 weeks of the experiment, one-third of the amount of food required to maintain their original live weight, lost 16% of their weight and 30 % of their total body energy. This weight loss consisted of 45 % water, 39 % fat and 13% protein. It appeared that tissue was mobilized inefficiently to meet a sudden energy deficit.When food was offered ad lib. to these sheep after they had maintained a liveweight deficit of about 11 kg for 8 weeks, they regained their weight in 5 weeks but only 75 % of their energy deficit. This was due to the high content of water (60 %) and low content of fat (23 %) in the regained tissue.The sheep that lost weight and then recovered it were, over-all, about 86% as efficient in their use of food to maintain body energy and produce wool as the sheep that maintained their original weight. s P a ce by Panaretto (1964) also indicated a marked decrease in fat during underThe efficiency of sheep during periods of alternate nutrition, but Hight & Barton (1965) concluded that under-nutrition and recovery can be assessed only protein loss was of greater importance, if the accompanying changes in body compositionThe aim of the present work was to measure the are known. Most of the reported work has been done changes in body composition of sheep which underwith growing animals, but Robinson (1948), by dis-went a period of severe caloric restriction, were section, and Beames & Morris (1965) by chemical then maintained at a low live weight and finally analysis of mature animals slaughtered at different recovered when food was offered ad lib. and to cornlevels of under-nutrition found that fat was more pare their efficiency with that of sheep which mainseverely depleted than other tissues. However, the tained their original weight. The changes in the body large variation between animals prevented a quanti-composition of living sheep during the experiment tative interpretation of these changes. Estimates of were predicted from multiple regression equations the body composition of living sheep derived from which related composition to the tritiated water • Present address: Abbott Laboratories Pty. Ltd., (TOH) space and live weight...

Utilization of nutrients as influenced by different restriction levels of feed intake under sub-tropical conditions in crossbred calves

“…Based on data from various experiments carried out at intakes higher than or equal to maintenance (Tyrrell and Moe, 1975), an increase in digestibility with reduction in level of intake was expected owing to a higher mean retention time of particles in rumen. However, absence of change in digestibility at low intake has been observed by some of the authors who worked at levels of intake lower than maintenance (Graham, 1964;Keenan et al, 1969) in sheep and (Agabriel et al, 1995) in cattle and Gingins et al (1980) observed the lowest digestibility at the lowest intake as has also been observed in the present study (Table 2). In the experiments where low intakes resulted in a decrease in digestibility, particle retention time, when measured, increased (Grimaud et al, 1998(Grimaud et al, , 1999.…”

Comparison of three methods for the in vivo estimation of body composition in dairy ewes

“…The lactation stage may introduce an error due to mammary development or water turnover changes [ I I ] but, in our conditions, this effect was not statistically significant, as previously observed in goats [13] [28]; 467 pl: [3]; 1 140 pl: [33]), in pregnant ewes (478 pl: [37]), at lambing (444 pi: [28]) or postweaning (369 pl: [37]; 161 pl: [28] [17], in mature wethers and rams [32] and in mature ewes [33]. The same tendency was observed in mature dry or lactating Holstein cows [6] and in steers [21 ].…”

The effects of diet, slaughter weight and docking on growth, carcass composition and meat quality of fat-tailed Barbarine lambs. A review

“…The carcass gain of lambs with an earlier nutritional history on L regimen had the higher muscle (524 vs. 399 g/kg) and lower fat (344 vs. 471 g/kg) concentration than unrestricted ones . The restriction of nutrients and subsequent compensatory growth can affect body or carcass composition particularly protein and fat deposition (Keenan and McManus 1969;Drouillard et al 1991). It was observed that in the compensatory period, lambs recovering from a period of food restriction deposited more protein and less fat in the carcass than did continuously high lambs (Hegarty et al 1999).…”