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Male broiler chickens were fed corn-soybean diets providing 2,700, 2,900, 3,100 or 3,300 kcal ME/kg. In all experiments, each treatment was tested with three replicate groups of 30 birds grown to 49 d of age. In Experiment 1, birds consumed the various diets ad libitum whereas in Experiment 2, all birds received identical and restricted quantities of feed so as to ensure variable intakes of energy. In a third experiment, after 7 d of age, broilers had access to feed in two feeders that contained only the highest level of energy, or the 3,300 kcal ME/kg diet in combination with one of the other diets previously described. Providing diets of 2,700 to 3,300 kcal ME/kg for ad libitum consumption had no effect on growth rate (P > 0.05) and energy intake was constant; however, reducing the energy level of the diet did result in reduced carcass fatness (P < 0.01). When feed intake was controlled in Experiment 2, there was reduced growth (P < 0.01) rate as energy level of the diet was reduced. This reduced growth was associated with dramatic reduction in carcass fatness (P < 0.01), although breast meat yield was not affected. When broilers were offered a choice of diets, they showed remarkably precise control of intake, such that energy intake was again constant across all treatments. However, even though energy intake was constant, broilers consuming the choice diets involving the lower energy content diets tended to have less carcass fat. It is concluded that the broiler still possesses a good ability to control its feed intake based on desire to normalize energy intake. As energy intake is decreased, or there is increased protein intake, the bird deposits less carcass fat.

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SYNOPSISMicrowave radiation has been clearly shown to result in enhancement of the rate of reaction for an imidization reaction. Analysis of the kinetic parameters showed that the apparent activation energy for the reaction was reduced from 105 to 55 kJ/mol, under the conditions of this experiment. The mechanism which has been proposed to explain this enhancement is based on the concept of a nonuniform temperature on a molecular scale, rather than a true reduction in the activation energy. 0 1992 John Wiley & Sons, Inc.

No abstract

Two experiments were carried out with male broiler chickens in which diets from 35 to 49 d of age were diluted by oat hulls and sand. In one experiment only energy was diluted; in the second experiment, both energy and protein (amino acid) levels were affected. Each diet was tested with four replicate floor pens each containing 25 1-d-old birds. All birds received a standard starter diet to 16 d and then grower diet to 35 d. In Experiment 1, dilution of only energy resulted in a significant linear (P < 0.01) reduction in body weight at 42 d, although there was growth compensation after this time such that all birds weighed the same at 49 d. Diet energy dilution resulted in increased feed intake, although energy intake was not maintained (P < 0.01). Diet energy dilution generally had little effect on carcass weight or yield of breast meat, although there was less abdominal fat (P < 0.01). In Experiment 2, dilution of both energy and protein had a comparable effect on growth rate as described in Experiment 1; however, in this study there was a linear decrease in carcass weight and breast meat yield as the diet was diluted. These results suggest that the male broiler chicken can grow quite well on very low energy diets but that a period of at least 7 d is required for adjustment to feed intake. Even with compensatory increase in feed intake, however, the bird is unable to maintain its energy intake when fed such diluted diets.

Day-old broilers were offered diets varying in dietary protein (16, 20, 24, 28, 32, 36%) and energy (2600, 2800, 3000, 3200, 3400, 3600 kcal [metabolizable energy] ME/kg) to 49 days of age to determine the effect of alteration in nutrient density on carcass composition and efficiency of nutrient utilization. Abdominal and total carcass fat contents responded similarly to alterations in dietary protein and energy, whether expressed on a percentage or absolute weight basis. However, maximum protein deposition occurred with the 20% crude protein diet, in contrast to the increase in percent carcass protein observed above this level. Although percent carcass protein decreased throughout the energy range tested, absolute carcass protein remained constant regardless of the dietary energy level. Dietary protein exerted similar effects on both absolute and percent carcass moisture. However, an increase in dietary energy resulted in a decrease in percent carcass moisture and an increase in absolute carcass moisture. Protein utilization decreased with each increment of dietary protein but increases in dietary energy resulted in small increases in protein utilization throughout the range tested. Changes in dietary protein and energy resulted in small differences in efficiency of energy utilization. Regression equations derived for carcass composition demonstrated that although diet composition is inadequate as a predictor of carcass parameters, the addition of carcass moisture (%) to the equation improves the reliability of the estimate. Equations for the prediction of nutrient utilization from diet composition are also presented.

The effect of dietary energy to protein balance, and early life caloric restriction on abdominal fat pad development in the male broiler chicken was studied. Dietary energy concentration had no significant (P s 0.05) effect on abdominal fat pad size, although decreasing the calorie.protein ratio of the diet resulted in a significant (P £ 0.05) reduction in the proportion of this tissue in the body. Reducing the calorie: protein ratio from a level considered optimum, by the addition of feather meal to the diet was equally as effective in reducing fat pad size as was the addition of a higher quality protein as exemplified by soybean meal plus DL-methione. Restricting the caloric intake of broilers in the 0-3 week growing period by the use of an ad libitum fed low energy diet (2233 kcal. M.E./kg.) had no significant (P s 0.05) effect on fat pad development. It is suggested that the degree of calorie restriction was not of sufficient magnitude to influence adipocyte hyperplasia. These results are discussed in relation to findings with other avian and mammalian species.