2. Pans which, by measurement, provided similar amounts of linear feeding space, differed significantly at some ages in total number of birds feeding or sleeping in them, and in the proportion of birds eating inside or from outside them.
3. Many design features interacted to influence ease of access to food, making straightforward recommendations difficult. It is desirable that birds be able to reach food easily from outside the pans. This was possible for 1‐d‐old chicks when pans 67 mm in height were filled to the brim. However, it was not until 7 d of age that birds could eat from the outside of pans 73 mm high with a very low food level.
4. Easy access to food from outside depended on the food not being covered up by birds inside; this required an internal width from pan edge to centre of at least 110 mm.
5. If possible, pan design should not permit birds to climb inside because they contaminate food and cover it up. In the designs observed, the width of the gaps in the covering frame was not the most important factor controlling pan entry. The proportion of birds entering pans did not fall to less than 10% until 23 d of age in pans with the smallest gap size, 61 mm. However, it reached this value at 17 d of age in pans with a 66 mm gap.
6. The depth, shape and steepness of the pan floor should not cause all the food to collect at the centre of the pan and out of reach of small chicks because this encouraged birds to enter pans to feed. Steep slopes also provide a poor foothold for birds leaving pans and cause repeated slipping.
7. The findings have implication for the interpretation of data from research trials in which access to food is manipulated but not fully described, and also in the commercial meat chicken industry for the design and purchase of feeding equipment, and the management and performance of birds. 相似文献
2. Chicks showed no significant alteration of their feeding behaviour in response to raising pen walls in the rearing facility from 30 to 60 cm.
3. Further analysis on a different set of birds revealed consistent short term individual differences in the frequency of feeding and non‐feeding pecks.
4. There were significant pen effects on behaviour suggesting the possible development of a pen ‘culture’ of pecking behaviour.
5. Pecking behaviours in 26 to 33 d‐old chicks, with the exception of drinking, were generally negatively correlated, so any non‐food pecking by a chick was generally associated with fewer pecks targeted at food.
6. By the age of two months chicks were pecking at food on the floor to a far greater extent than at any food presented in food trays. 相似文献
2. The least floor area (0.035 m2/bird) depressed production in two‐bird cages. Floor area had little effect on the performance of larger colonies.
3. Birds in colonies of three, four or six laid and survived equally well when feeding space/bird and floor area/bird were constant.
4. Production per hen d and food intake were higher, but return on estimated capital outlay was lower, with 102 mm than with 76 mm feeding space/bird when colony size and floor area/bird were constant.
5. Production and food intake of birds which were not treated to prevent cannibalism declined, and mortality increased, as cage depth increased from 385 to 915 mm concomitantly with increasing colony size from 2 to 7 birds and decreasing feeding space from 152 to 43 mm/bird.
6. Increasing cage depth did not increase the proportion of cracked eggs.
7. Mortality was higher among birds fitted with plastic spectacles than among debeaked birds. 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. Birds in conventional deep cages were more active than those in shallow cages in each of four different periods of day. Activity reached a peak between 11.00 and 13.00 h irrespective of cage shape.
3. Mean feeding activity was greater in the shallow (45.6%) than in the conventional deep cages (39.9%).
4. Mean feeding activity was greater in birds fed ad libitum (43.3%) than in those fed on a restricted diet (40.4%).
5. Although restricted birds in shallow cages showed more feeding activity than those in conventional deep cages they consumed less food (56% against 67%) in the 7 h between supply of their daily ration and the onset of the dark period.
6. Feather damage was greater in the conventional deep cages than in the shallow cages.
7. The more efficient utilisation of food by hens in shallow cages is probably due largely to three factors: reduced levels of motor activity and general disturbance, a more leisurely eating pattern and better feather cover. 相似文献
2. Chicks on treatments 1 and 2 were fed continuously while those on treatments 3 and 4 were fed during the day (from 06.00 h to 18.00 h) and night (from 18.00 h to 06.00 h) respectively. Chicks on treatment 1 received only natural light during the day, while those on treatments 2, 3 and 4 received supplementary lighting during the night in addition to natural light during the day.
3. Food consumption by birds on treatment 2 was significantly higher at 56 days of age, followed by birds on treatments 1, 4 and 3.
4. The pattern of body weight gains was similar to the order of food consumption.
5. Efficiency of food utilisation was poorest for birds on treatment 2.
6. Mortality rates were not influenced significantly by the feeding regimen and lighting pattern.
7. Dressing percentage and proportion of abdominal fat were greatest for birds on treatment 2. 相似文献
2. Four of the birds maintained a circadian rhythm, in two the rhythm was 24 h while in the other two it was slightly in excess of 24 h.
3. In all birds, feeding activity was less in the 12 h before oviposition than in the 12 h after.
4. When only the first egg of a clutch was considered, it was found that a low level of feeding activity was associated with the release of luteinising hormone (32 h before oviposition), there was then a sharp increase at ovulation to a new level which was maintained from about 23 to 18 h before oviposition and then a decline in feeding occurred until a few hours before laying.
5. There was variation in the amount of feeding activity shown in the few hours before oviposition. 相似文献
2. Plasma VLDL concentrations were consistently higher at all ages in fat line hens but were not affected by dietary treatment.
3. Mature body weight did not differ between the lines in birds fed ad libitum but with food restriction throughout life, fat line birds were lighter at 34 weeks.
4. There was little difference between the lines in abdominal fatness of birds fed ad libitum up to 60 weeks. Fat line birds were always fatter than lean line counterparts under food restriction.
5. Egg production was higher in lean line birds fed ad libitum but food restriction improved egg production in both lines. Peak egg productions were similar in both lines but there was evidence that the optimal food allowances for egg production was higher in the lean compared with the fat line.
6. Ovarian yellow follicle numbers were highest at 34 weeks in ad libitum fed lean line birds and declined linearly with decreasing body weight caused by food restriction but there was no such relationship in fat line birds.
7. White follicle numbers were higher and follicular atresia was lower in the lean line.
8. It is concluded that poor reproduction in fat line birds was associated with inhibition of follicular development and atresia rather than by high plasma VLDL concentrations promoting excessive yolk formation. 相似文献
2. In experiment 1, 72 individually caged ISA Brown pullets were fitted at 16 weeks of age (point of lay) with either ‘ring’ or ‘bumper’ beak devices or no device (control), half being fed on pellets and half on mash. The devices were held in place by lugs inserted in the nares.
3. There was evidence of discomfort immediately after fitting the devices, but not thereafter. In the first week, the devices reduced food intake, and were removed from 7 (15%) birds that lost weight consistently. Between 16 and 21 weeks, however, there were no significant effects of beak treatment or food form on either total food intake or egg production with the 65 remaining birds.
4. Beak treatment did not affect feeding efficiency (food intake per minute of feeding). The only behaviour affected was pecking at birds in adjacent cages, which was reduced with the ring device.
5. At 21 weeks, the birds were placed together in groups of 4 to 6 in 12 pens, each group consisting of birds from one of the 6 original treatments, and their behaviour was observed in experiment 2 between 21 and 23 weeks.
6. The only effects of beak treatment on behaviour were that pecking at pen walls was increased with the ring device, while pulling and eating feathers from group mates was seen mainly with control birds fed on pellets. Two birds were cannibalised in a control group on pellets.
7. Devices came off 3 (7%) birds in experiment 1 and were replaced, and rings slipped over lower mandibles of 2 (5%) birds in experiment 2 and were corrected.
8. At 23 weeks, beak lengths were increased with ring and bumper treatments, and pecking damage scores were low with all treatments.
9. It is concluded that these devices are not applicable commercially, but further trials would be justified with new improved designs. 相似文献
2. Birds exposed to a 2 h light(L): 10 h dark(D) lighting schedule with feeding restricted to the light periods ate significantly less food and grew more slowly than conventionally‐reared birds. Satisfactory growth and efficiency of food utilisation were obtained by allowing these birds access to food during the dark periods.
3. Altering the lighting schedule to 2L:6D resulted in birds with food intakes and growth rates similar to those reared conventionally, even when feeding was restricted to the light periods.
4. Releasing birds from the light and food restriction for the 2 weeks preceding slaughter resulted in greater food consumption which was not characterised by significantly better growth or food utilisation.
5. Feeding a diet of high energy or pelleting a diet of low energy during the period of restriction increased food intake and improved growth rate.
6. The response of broilers to intermittent lighting and feeding was not significantly influenced by ambient temperature within the range 16 to 35 °C or by the energy concentration of the diet fed before the introduction of the intermittent schedule. 相似文献
2. The proportions of ingredients eaten by the chickens given a free choice varied widely during the first 56 h of the trial. Thereafter, the proportions did not vary widely and birds given the free choice ate approximately ½ of their intake as whole wheat, ? of their intake as concentrate (high protein meals plus vitamin and mineral premixes), and 1/7 of their intake as whole sorghum each week for the three‐week trial period.
3. The nutrient composition of the free‐choice diet selected by the birds over the trial period averaged 12.09 MJ ME/kg feed, 210 g/kg crude protein, 14 g/kg calcium and 7 g/kg phosphorus.
4. At the end of the trial the average live body weights of the birds differed significantly according to method of feeding, in the descending order of pellets > mash > free choice.
5. The empty gizzard weight of birds differed significantly according to the method of feeding, in the descending order of free choice > mash > pellets.
6. The plucked empty bodies of birds given the free choice had a significantly lower concentration of crude protein than the plucked empty bodies of birds fed on mash or pellets. There were no significant differences between the treatments in the plucked empty body concentrations of fat, calcium or phosphorus.
7. Financial analysis indicated that free‐choice feeding was more profitable than feeding mash or pelleted diets to broiler chickens by 3.6% and 33.4% respectively. 相似文献
2. Food‐restricted birds spent a large proportion of time scratching and pecking the litter compared with birds fed ad libitum.
3. The heterophil/lymphocyte ratio and the proportion of basophils were raised at 8, 12 and 16 weeks, and the plasma concentrations of corticos‐terone were higher at 8 and 12 weeks of age in restricted birds compared with those fed ad libitum.
4. Creatine kinase activity was higher in broiler breeders fed ad libitum compared with layers and restricted broiler breeders. The activity of aspartate transaminase was higher in restricted layers compared with birds fed ad libitum and was similar in broiler breeders.
5. Plasma viscosity was lower in food‐restricted compared with ad libitum‐fed birds.
6. Limiting access to water had little or no effect on the welfare indicators although food‐restricted birds with free access to water spent more time drinking than birds fed ad libitum.
7. There were no important differences between the two broiler strains. Layers spent less time resting than broiler breeders and had higher plasma corticosterone concentrations at 3 and 16 weeks of age.
8. It was concluded that there was evidence for physiological stress associated with restricted feeding at least between 8 and 16 weeks of age. It was suggested that the altered behaviour of broiler breeders kept on litter may indicate that they can cope with food restrictions and that this may be acceptable in relation to the long‐term benefits of limiting body weight during rearing. The same may not be true for layers. 相似文献
2. Predation was higher in BA than HB.
3. Mortality through disease was higher in RIR than BA and HB.
4. Crossbred HB birds show the lowest combination of mortality and predation, suggesting a heterosis effect.
5. Mortality did not differ on farms and in field environments, suggesting an inability to improve biosecurity in farm conditions.
6. There was a positive relationship between eggshell strength and mortality. Calcium depletion from the birds’ bones, limiting foraging and escaping ability may be the explanation, which ultimately increases susceptibility to disease and predation. 相似文献
2. More eggs were produced per hen housed from 30 to 70 weeks in the shallow cages; the difference approached significance.
3. The pattern of feeding activity over the day was significantly more U‐shaped in the shallow cages; this pattern accords more closely with physiological requirements.
4. Feather damage caused by pecking was slightly but significantly more severe in the deep cages at 70 weeks.
5. The proportion of cracked eggs (collected from 60 to 70 weeks) was significantly lower in the shallow cages.
6. The arrangement of the hens was such that within the shallow cages a higher proportion of birds was present in the front half.
7. It is suggested that some of the advantages conferred by the shallow cage may be related to the greater accessibility of the food trough. 相似文献
2. The extent of agreement between inspection and revision ranged between 83.2 and 86.2%.
3. Agreement between inspectors and revisors was higher for the category of approved birds than for the condemned category.
4. Differences in the criteria used to assess the birds were observed.
5. The conclusion was drawn that findings in meat inspection require further discussion to reach an agreed standard. 相似文献
2. Starving and resting rates of heat production (SHP and RHP) were measured, over 1‐d periods, at intervals during a 25‐week period in which the experimental birds were individually restricted to 80% of their previous energy intake ad libitum.
3. In both strains mean RHP per bird was about 7% lower in the restricted birds than in controls fed ad libitum, but when RHP was expressed in terms of metabolic body size (kg0.75) the two groups did not differ.
4. Mean SHP per bird was about 18% lower in the restricted birds of both strains than in the corresponding controls; the decrease in SHP per kg0.75 was 12%.
5. Heat increment of feeding and calculated maintenance energy were higher, and net availability of metabolisable energy for maintenance and production was lower, in the restricted than in the control groups.
6. Gross efficiencies of egg production, in terms of both mass and energy, increased in the restricted birds.
7. Live‐weight and total carcass energy after 25 weeks of restriction were respectively about 15% and 30% lower in the restricted groups of both strains than in the groups fed ad libitum. 相似文献
2. Wet mashes fed in the hot dry season caused significantly lower rates of panting, a major thermoregulatory behaviour. This may be an indication of increased comfort in hot dry conditions for birds fed wet mashes.
3. Feeding activities of birds fed dry and wet rations respectively increased and decreased with decrease in seasonal temperature. The peaks of both feeding activity and consumption in the cool‐dry season were attained by birds fed dry diets and in the hot dry season by those fed wet mashes.
4. Diurnal distributions of food and water intakes were more even in the hot dry season for those fed wet mashes. This may again suggest a higher degree of comfort on the hot dry season when birds are fed wet mashes.
5. In the hot dry season, 60% of birds preferred wet mashes, whereas 80% of birds preferred dry meal in the cool dry season. This may be attributable to the lower temperature of wet mashes.
6. Similar patterns in feeding activity, food consumption and daily weight gain occurred in response to dietary presentation and season.
7. Feeding of dry meal under cool dry conditions and wet mashes in the hot season may be advantageous. Irrespective of season, water temperature may have to be raised to about 30°C before addition to meals for chicks under brooding. This may be necessary as preliminary investigations in this laboratory indicate that food temperatures below 22°C may at the brooding stage discourage food intake and activities. 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. Extrusion cooking of rice bran resulted, in improved chick weight gain and food efficiency for the first two weeks of feeding, but this advantage was lost by the end of the feeding period.
3. Addition of 10 g calcium/kg to the stabilised rice bran diet prevented the decline in performance after two weeks of age, and birds fed on this diet continued to gain at an increasing rate until the end of the experiment.
4. Calcium supplementation of stabilised rice bran diets produced significantly greater gains and superior food utilisation compared to stabilised rice bran diets without added calcium.
5. Calcium supplementation did not affect weight gain of chicks fed on diets containing raw rice bran.
6. Taste panel evaluation of meat from birds fed on diets containing raw rice bran, stabilised rice bran, or no rice bran indicated a significant preference in only one combination tested. Any ‘off flavour could not be related to dietary treatment. 相似文献
2. Whole blood viscosity was more than twice as high, and plasma triglyc‐eride and haemoglobin concentrations were over 30% higher in fat line than in lean line females fed ad libitum or in restricted birds of both genotypes.
3. Mean cell haemoglobin concentration was higher and mean cell volume lower in fat compared with lean line females.
4. Food restriction was associated with lower plasma triglyceride concentrations, lower numbers of heterophils and monocytes and a lower heterophil‐lymphocyte ratio.
5. Fat line birds had a higher blood pCO2 and lower pH than lean line birds.
6. Thermal stress was associated in ad libitum‐fed birds with a rise in blood pH and a decrease in pCO2, and in restricted birds with a decline in blood pH and an increase in pCO2.
7. Blood creatine kinase activity increased in all groups under thermal stress. 相似文献