The effect of live weight gain and live weight loss on body composition of Merino wethers: chemical composition of the noncarcass organs and the empty body.

Chemical composition of the noncarcass organs, combined noncarcass organs, and fleece-free empty body (FFEB) was measured during live weight gain (LWG) and live weight loss (LWL) to determine the effect of different periods of normal and retarded growth on chemical composition of noncarcass organs and FFEB. Thirty-five Merino wethers had ad libitum access to the experimental diet (17.23% CP and 12.09 MJ/kg of DE) to grow from 23.0 to 33.0 kg live weight and then were fed to lose a total of 10 kg in three periods of 25 d each at the rate of 133 g/d. Groups of five wethers were slaughtered at live weights of 23.0, 26.3, 29.6, and 33.0 kg during LWG and 29.6 (first period), 26.3 (second period), and 23.0 kg (third period) during LWL. The lower combined noncarcass weight in LWL wethers than in LWG wethers at 23.0 and 26.3 kg of live weights was due to the significantly lower protein weight at 23.0 and 26.3 kg (P < .01) and water weight at all common slaughter weights (P < .01). Chemical fat in the combined noncarcass organs was significantly greater in LWL wethers than in LWG wethers at 23.0, 26.3 (P < .01), and 29.6 kg (P < .05). The general increase of chemical fat in the combined noncarcass organs of the LWL wethers was mainly due to the significant increase in the chemical fat in the head and feet at 23.0 (P < .01), 26.3, and 29.6 kg (P < .05), liver at 23.0 kg (P < .01), and total alimentary tract fat at 23.0 (P < .01) and 29.6 kg (P < .05). Although fleece-free empty body weight (FFEBW) was similar in LWG and LWL wethers at all common slaughter weights, FFEB water weight was lower significantly in LWL wethers at 23.0, 26.3 (P < .01), and 29.6 kg (P < .05) and that of chemical fat was greater significantly in LWL wethers at 23.0 (P < .01), 26.3, and 29.6 kg (P < .05) than in LWG wethers. Wethers after weight loss had more chemical fat and less water in their FFEB than normal growing wethers at the same FFEBW.

The effect of live weight gain and live weight loss on body composition of merino wethers: noncarcass organs.

The weight of the noncarcass external tissues, thoracic organs, and visceral organs was measured during live weight gain (LWG) and live weight loss (LWL) to evaluate the effect of different periods of normal and retarded growth on noncarcass organs. Thirty-five Merino wethers were allowed ad libitum access to an experimental diet of 80% alfalfa chaff and 20% cereal grain (17.23% CP and 12.09 MJ/kg of DE) to grow from 23.0 to 33.0 kg live weight and then fed to lose 10 kg at 133 g/d. Groups of five animals were slaughtered at live weights of 23.0, 26.3, 29.6, and 33.0 kg during LWG and 29.6, 26.3, and 23.0 kg during LWL. Although total weight of noncarcass organs was significantly lower in LWL animals than in LWG animals at 23.0- and 26.3-kg (P < .05) common slaughter weights, the weight of some noncarcass organs was significantly greater in LWL animals. For example, the weight of the head at 23.0 and 26.3 kg (P < .05), of the feet and esophagus at 23.0 (P < .01) and 26.3 kg (P < .05), and of the total alimentary tract fat at 23.0 kg (P < .01) was greater in LWL wethers. Weights of other organs, however, were lower in LWL animals.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of live weight gain and live weight loss on body composition of merino wethers: chemical composition of the dissected components.

Chemical composition of the dissected side parts and dissected side was measured during live weight gain (LWG) and live weight loss (LWL) to determine effects on the chemical composition of the dissected side parts. Thirty-five Merino wethers had ad libitum access to the experimental diet (17.23% CP and 12.09 MJ/kg of DE) to grow from 23.0 to 33.0 kg live weight and then were fed to lose a total of 10 kg in three periods of 25 d each at the rate of 133 g/d. Groups of five animals were slaughtered at live weights of 23.0, 26.3, 29.6, and 33.0 kg during LWG and 29.6 kg (first period), 26.3 kg (second period), and 23.0 kg (third period) during LWL. The greater dissected side weight in LWL animals than in LWG animals at 23.0 kg of live weight was due to the significantly greater chemical fat (P < .05) in the LWL animals than in the LWG animals at 23.0 kg. There were no significant differences between treatments in the protein and water weights in the dissected side. The general increase in the chemical fat in the dissected side of the LWL animals was due to the significant increase in the chemical fat in the muscle (P < .01) and bone (P < .01, 23.0 and 26.3 kg and P < .05, 29.6 kg) at each common slaughter weight and subcutaneous fat (P < .05), intermuscular fat (P < .05) kidney and channel fat (P < .05), and total side fat (P < .01) at 23.0 kg.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of live weight gain and live weight loss on body composition of Merino wethers: dissected muscle, fat, and bone.

Sheep were slaughtered after live weight gain (LWG) and live weight loss (LWL) to evaluate the effect of different periods of normal and retarded growth on dissected carcass components. Thirty-five Merino wether sheep were allowed ad libitum access to the experimental diet of 80% alfalfa chaff and 20% cereal grain (17.23% CP and 18.10 MJ/kg of GE) to grow from 23.0 to 33.0 kg live weight and then fed to lose 10 kg at 133 g/d. Five animals were slaughtered at live weights of 23.0, 26.3, 29.6, and 33.0 kg during LWG and 29.6, 26.3, and 23.0 kg during LWL. Fleece-free empty BW was similar in both LWG and LWL animals at all common slaughter weights because of the lesser and greater weights of the alimentary tract contents and the fleece, respectively, in the LWL animals. Carcass weight or dissected side weight was greater in LWL animals at each common slaughter weight but significantly so (P less than .05) at the 23.0 kg live weight only. Total side muscle weight was similar in LWG and LWL animals at each common slaughter weight, but the proportion of muscle in the dissected side weight was lower (P less than .05) in LWL animals at 23.0 kg live weight. Total side fat, subcutaneous fat, intermuscular fat, and kidney and channel fat weights were all greater in LWL animals at each common slaughter weight, but significantly so (P less than .05) at the 23.0 kg live weight only. Total side bone weight was higher at both 26.3 kg (P less than .01) and 23.0 kg (P less than .05) in the LWL animals. Weight loss in young sheep mobilized more weight of muscle than fat from the carcass, whereas bone weight was constant.