2. Food intake was measured daily for 21 d. Body composition was determined at 42 d and gains in body mass, protein, fat and gross energy calculated by comparison with a group analysed at 21 d. Heat production was calculated by difference between AME intake and energy gain.
3. Decrease of food mass intake with increased dietary AME concentration limited the increase in AME intake to about 25%, despite the near 2‐fold range of AME concentrations.
4. There was no effect of CP concentration on food mass intake. CP intake was directly related to CP: AME ratio.
5. When body weight differences were taken into account, heat production was independent of dietary AME concentration, but increased by about 8% on the higher‐protein diets.
6. There were strong linear correlations between dietary CP:AME ratio and carcase protein: energy ratio, carcase fat content and carcase protein content.
7. It was concluded that the growing fowl responded to dietary nutrient: energy ratio, and the associated differences in nutrient and energy intakes, by varying the rate of energy deposition as fat, without regulatory variation of energy dissipation as heat. 相似文献
2. Fenfluramine produced a curvilinear decrease in food intake and body weight in adult layers and growing broilers.
3. Inconsistent responses to furanone and crotonolactone were obtained with adult layers and broilers in cages, but a similar decrease in food intake and body weight for both drugs was recorded in male broilers raised in floor pens.
4. The responses to subcutaneous injection of 20 mg/kg of each drug on food intake over 24 h were comparable to those for dietary inclusion. Fenfluramine, however, produced a greater response in male compared with female broilers and induced signs of hyper‐thermia in broilers and layers.
5. Subcutaneous injection of 50 mg crotonolactone/kg was associated with decreases in the food intakes of 4 strains and there was evidence of different responses between lines.
6. It was concluded that none of the drugs used were likely to be suitable for the control of food intake in broiler breeder flocks. 相似文献
2. Hyperphagia, amounting to twice the intake of control birds early in the experiment, occurred on the repletion day.
3. Final body weight attained 80% of that of the controls.
4. Body fat concentration decreased at first but returned to that of controls after 3 weeks.
5. A consistent hyperlipaemia was observed after food deprivation or restoration.
6. There was a marked increase in the digestive enzymes found in the small intestine, but not in the pancreas during the repletion day.
7. These responses may be considered as mechanisms to reduce the physiological manifestations of starvation. 相似文献
2. LLM appears to be a good source of protein and calcium.
3. Food intake was not significantly affected (P>0.05) with dietary LLM inclusion up to 200 g/kg.
4. Inclusion of LLM up to 150 g/kg diet did not influence significantly (P>0.05) the performance of broilers in terms of body weight gain and food efficiency. However, inclusion of LLM at 200 g/kg diet had an adverse effect on weight gain and food efficiency, when compared to other dietary treatments. The profitability over food costs was low with the 200 g LLM/kg diet compared to those of other diets.
5. It may be inferred from these experiments that LLM can safely be included in broiler diets up to 150 g/kg.
6. Studies using force‐feeding and restricted feeding techniques indicated that reduced food intake was not responsible for the growth depression in diets containing higher amounts of LLM. 相似文献
2. Increases in food consumption were accompanied by increases in egg production.
3. The food required per dozen eggs was improved by up to 100 g dietary DPM/kg and variation in the sizes of eggs laid depended on the hybrid.
4. Concentrations of DPM up to 100 g/kg did not affect the water‐soluble nitrogen content of the egg but the crude albumen nitrogen content was depressed at concentrations of 80 g/kg or above.
5. Feeding DPM to laying pullets depressed body weight. 相似文献
2. Brain serotonin, 5‐hydroxyindoleacetic acid and norepinephrine concentrations were increased dose‐dependently with 1.0, 2.0 and 3.0 g/kg supplemental dietary tryptophan.
3. Supplemental dietary tryptophan had no effect on body weight gain, food intake, food efficiency or mortality.
4. Carcase and individual thigh weights were significantly heavier in those birds fed l.0 g/kg supplemental tryptophan. 相似文献
2. The quail were kept in open‐circuit respiration calorimeters, so that diet selection could be related to energy requirement.
3. Increasing ambient temperature had no significant effect on food intake by weight, but the proportion of the high energy choice decreased and, conversely, the proportion of the lower‐energy but higher‐protein choice increased.
4. Energy intake was therefore negatively correlated with ambient temperature, but protein intake per unit of energy intake increased, allowing the birds to gain weight at about the same rate at all temperatures.
5. Heat production decreased as ambient temperature increased. Respiratory quotient decreased with increasing temperature, which indicates a reduced utilisation of carbohydrate as an energy source.
6. Water intake increased with temperature but there were no overt signs of heat stress and there was no significant change in body temperature.
7. Japanese quail selected a dietary mixture which maintained similar growth rates over a wide range of ambient temperature, by sustaining protein intake but altering energy intake in line with thermoregulatory energy demands. 相似文献
2. Treatments did not affect egg numbers, food consumption, conversion efficiency of food to egg, bodyweight gain or mortality.
3. Increasing dietary calcium (Ca) significantly increased plasma Ca and inorganic phosphorus (P), breaking strength at the radius and egg specific gravity and significantly decreased plasma alkaline phosphatase and egg weight.
4. Increasing dietary phosphorus increased plasma P and decreased egg specific gravity significantly.
5. Plasma Ca, P and alkaline phosphatase and radius breaking strength were suitable indices of the Ca status of the hens. 相似文献
2. In two experiments, newly hatched hybrid and Brown Leghorn chicks were reared in isolation and in small groups of different sizes, and their growth, food intake and feeding activity were measured for several eeks.
3. Initially, chicks of both strains grew faster when they were grouped than when they were in isolation, as a result of a more efficient conversion of food rather than as a result of increased consumption.
4. Later, chicks in the largest groups converted their food less efficiently, possibly because of increased disturbance.
5. From 6 to 12 weeks, when the chicks were in larger cages, growth rate was not affected by group size, but food intake and food conversion were affected differently in the two strains.
6. In general, the isolated chicks ate about the same amount as the grouped ones, and it is doubtful whether social facilitation of feeding occurred at all in these experiments. 相似文献
2. The inclusion of AA improved egg production, food intake and efficiency of utilisation, and decreased the cost of food per kg egg. The addition of 400 mg AA/kg diet gave the most efficient performance.
3. Palm oil inclusion reduced the effect of heat stress and increased egg production, egg weight, food intake and efficiency of utilisation.
4. When 200 mg AA and 50 g palm oil/kg were used, additive responses were obtained with further improvements in egg production, food cost and efficiency.
5. Ascorbic acid and palm oil when fed alone or in combination reduced the incidence of cracked eggs.
6. Thus, 400 mg ascorbic acid/kg of diet, 50 g palm oil or 200 mg AA plus 50 g palm oil/kg diet ameliorated the effects of heat stress in laying hens. 相似文献
2. In the first experiment (winter), food denial for 8 h/d improved food conversion efficiency and increased dressing percentage. Increasing nutrient concentration increased growth rate; decreased food intake; and improved conversion efficiency.
3. In the second experiment (summer), food denial for 8 h/d tended to increase growth rate and to improve conversion efficiency, but not significantly. Increasing nutrient concentration had the same effect as in experiment 1.
4. It is concluded that restricted access to food generally improves food efficiency. 相似文献
2. Groundnut meal, groundnut meal adjusted with indispensable amino acids or sesame meal supplied the dietary CP at 180 g/kg diet. Increments of lysine (1.5 g/kg diet) were added to each of these diets.
3. The gain, food intake and food efficiency responses of broiler chicks were analysed using a quadratic equation and a two‐slope method. An estimate of lysine requirements was also obtained from a survey of college students.
4. The different methods produced widely different estimates of lysine requirement.
5. The average lysine requirement was estimated at 50.1 g lysine/kg CP for groundnut meal, 61.7 for adjusted groundnut meal and 54.9 for sesame meal.
6. Reasons for the effect of statistical analysis and protein source on lysine requirement are discussed. 相似文献
2. Several combinations of dietary PHGG and GG at 50 g per kg diets were prepared for a feed intake experiment. Birds (17‐d‐old) were given diets for 3 h after 16 h fasting, and food consumption was measured at 1 h intervals. The food intake rapidly decreased as the dietary GG content increased even at 1 h after feeding.
3. The rate of food passage from the crop was also investigated with birds (20‐d‐old) after 16 h fasting. Birds were tube‐fed diets having several ratios of dietary PHGG and GG. After 1 h of feeding, the diet remaining in the crop was measured after drying. The crop emptying rate decreased linearly as dietary PHGG concentration decreased.
4. The present study suggests that partial hydrolysis of dietary GG improve both feeding behaviour and food passage from the crop in growing chicks. 相似文献
2. Growth rate, food intake, food utilisation and proportion of dietary nitrogen retained were much poorer in chicks receiving salseed meal.
3. The chicks receiving salseed meal developed pathological lesions in liver and kidney.
4. The red blood cell count, white blood cell count, haemoglobin concentration and packed cell volume of the chicks receiving salseed meal were lower than those of chicks receiving maize.
5. The apparent metabolisable energy value of salseed meal was determined as 6.83 MJ/kg. 相似文献
The fats concerned were soyabean oil, soyabean soapstock, maize oil, lard, grease and tallow. Their effect was studied by using regression analyses.
It was found that the addition of fat, both animal fats and vegetable oils, diminishes food intake. The food intake decreases significantly with rising percentages of fat according to a linear function. No differences in effect between various fats could be demonstrated.
The incorporation of various fats improves the weight gain, although the increase was not related to the amount of fat added. The improvement in weight gain differs from one fat to an other.
The addition of fats improves efficiency of food conversion, but varies according to the kind of fat. Here the improvement is correlated with the level of fat added.
The difference in improvement of food conversion can be only partially explained by differences in absorbability and metabolisable energy of the fats.
It is concluded that certain fats ameliorate the efficiency of food conversion and, in some cases, weight gain to a higher degree as may be expected from their metabolisable energy content. It might be possible that some fats possess one or more factors which improve the efficiency of metabolisable energy or exert a protein anabolic action. 相似文献
2. Increased mortality, perosis and other pathological changes involving a number of tissues were observed in birds fed on a low‐choline diet.
3. Methionine replaced part of the dietary requirement for choline at low dietary choline concentrations.
4. High dietary concentrations of choline (> 1 750 mg/kg) increased the requirement for dietary TSAA.
5. Increasing the dietary choline while maintaining the TSAA at an inadequate level may decrease performance. 相似文献
2. There was no effect of age at restriction (15 to 18 compared with 19 to 22 weeks) on the number of yellow follicles.
3. The treatment with the larger body weight of two groups given the same degree of restriction (maintenance) had more follicles than the treatment which had a smaller body weight.
4. There was a positive linear relationship between the number of yellow follicles and body weight and food intake. Addition of the weight of fat or age at first egg to the model increased the residual mean squares.
5. The proportion of atresia among yellow follicles and the incidence of internal ovulation increased with body weight at first egg.
6. It was concluded that the physiological processes occurring during rearing which underlie ovarian function are reflected solely in the body weight and food intake of broiler breeders at first egg. 相似文献
2. In only one experiment was weight gain significantly improved when the barley was heated.
3. Autoclaving barley at 120 °C for 30 min reduced dietary dry matter digestibility and treating the barley with dilute acid before heating had no effect on its nutritive value.
4. Supplementing diets containing commercial barley with a‐amylase produced slightly conflicting results in that there was an improved weight gain, food conversion efficiency and digestibility value in two of three experiments.
5. The digestibility and metabolisable energy values of a North American six‐row spring barley (Glacier) were significantly improved by enzyme supplementation.
6. The effect of the enzyme on diets containing a high amylose barley (Glacier Pentlandfield) was positive but not significant. 相似文献
2. Because the traditional method of determination of droppings digestibility coefficients of nitrogen may lead to systematic errors in estimating the feeding value of foodstuffs, a method is proposed to determine the ileal digestibility coefficients. The ileal method is compared with the droppings method for a mixed food and for two foodstuffs: wheat and solvent‐extracted soyabean meal.
3. Birds selected for efficient food conversion showed distinctly higher digestibility coefficients for all nutrients than birds selected for high growth potential or birds from a commercial strain.
4. The influence of age on digestibility coefficients was not consistent.
5. Female birds showed digestibility coefficients which were, in general, 3% higher than those of male chickens.
6. Interactions between genotype and sex and between genotype and age for energy metabolisability were the only interactions observed for digestibility measurements.
7. The method of determination influenced the amino acid digestibility coefficients of the mixed food and the relative feeding values of wheat and soyabean meal.
8. It is important to use well defined animals (genotype, sex, age) in evaluating foodstuffs.
9. The preferred method for determination of digestibility coefficients of nitrogen and amino acids is based on ileal sampling, although the differences in amino acid digestibility coefficients were small between methods. 相似文献
2. Breeder hens fed ad libitum and subjected to either conventional or intermittent lighting ingested respectively, 25 g and 14 to 17 g more than hens restricted to 115 g/d.
3. Body weight was greater in hens fed ad libitum irrespective of the lighting pattern and of the amount of food intake.
4. Persistency of egg production was impaired by intermittent lighting.
5. Ad libitum feeding reduced egg fertility. The decrease was larger in breeder hens on intermittent lighting.
6. Hatchability was increased in hens submitted to the symmetrical lighting pattern (0.5L:3.5d).
7. Egg and chick weights were higher in hens fed ad libitum.
8. Shell index and shell breaking strength increased in restricted hens on the intermittent lighting pattern (0.5L:3.5d) × 6.
9. The best performance was obtained in restricted hens on the conventional lighting pattern. 相似文献