No abstract

Rate of gain by final weight response surfaces for gain of empty body water, protein, lipid and ash were defined with data from 62 male Sprague-Dawley rats. Rats were fed for 21 days at 100, 88, 76, 64, 52 or 40% of ad libitum intake within each of five initial weight groups ranging from 84 to 286 g. Forty additional rats were killed at the beginning of the growing period to provide initial estimates of amount and composition of empty body weight. Water in the gain decreased (P less than 0.05) and lipid increased (P less than 0.05) with increasing final weight. Gains of protein and ash were not significantly affected by final weight. Gains of water, protein and lipid increased (P less than 0.05) linearly with increasing rates of gain. The relationship between rate of gain and composition of gain was not affected by different final weights. Averaged across final weight, at all rates of gain each gram of gain was composed of about 66.9% water, 18.8% protein, 10.6% lipid and from 1.0 to 2.5% ash. Thus, each additional unit of gain per unit time was composed of the same amount of water, protein, lipid and about the same amount of ash. Therefore, over the stage of growth examined, these results demonstrate that the rates at which rats grow do not influence the composition of their gain to a particular weight.

Chloroform was a satisfactory replacement for ether in solvent extraction for lipid determination in freeze-dried animal tissues, although values obtained were not identical. Fat content of tissues used in this study ranged from less than 10 to more than 95%. Chloroform has the great advantage of being fireproof, but proper fume hoods should be used. An antifoaming agent should be added to chloroform, both in the Soxhlet apparatus and when it is redistilled.

Suppressed development of edible portion in carcasses from cattle fed hay during the early feeding period (216-340 kg live weight) was followed by compensatory growth during the intermediate (341-409 kg live weight) and final (410-454 kg live weight) periods. However, when silage in the early feeding period was followed by corn concentrate in the intermediate period, no increased 'edible portion' development was achieved beyond that produced by continuous silage. The final feeding period (corn concentrate) resulted in a decline in ' edible portion' percentage in cattle that previously received concentrate in the intermediate period whereas those that previously received silage remained at about the same percentage.Cattle fed hay during the early period had less (P < 0-01) carcass weight, less (P< 0'01) fat cover, and more (P < 0-01) reticulo-rumen weight than those fed corn silage for the same period, regardless of slaughter weight.In the heavy (409 and 454 kg) slaughter groups, cattle fed silage in the early period had higher (P < 0-05) marbling scores than those fed hay. Feeding silage in the intermediate period resulted in lower colour (P < 0-01) and firmness (P < 0-01) scores in the longissimus dorsi muscle than feeding concentrate at that time. The dietary regimes used in these studies resulted in widely varying growth rates among treatments with consequential differences in the average age of the animal groups at slaughter. Therefore, the treatment effects observed seem to be easily explicable on the basis of age differences.

. 1993. Effect of oat bran, cotton seed hulls and guar gum on chicken egg and blood lipids during the early laying period. Can. J. . Fifteen Leghorn pullets were assigned to each of four experimental diets: basal layer ration or basal ration containing 30% oat bran, 3% cotton seed hulls or 0.5% guar gum from 19 to 25 wk of age. Inclusion of oat bran and cotton seed hulls lowered (P < 0.05) egg yolk cholesterol concentration 6to7%, but had no significant (P > 0.05) effects on early production parameters.