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2. Body weight and food utilisation efficiency of White Leghorns at 10 d of age were not affected by diet, whereas the lower concentrations of lysine and methionine depressed these traits in White Rocks.
3. Tryptophan deficiency reduced food intake of White Leghorns, but not White Rocks.
4. With choice feeding of balanced and deficient diets from day 10 to 16, preferences between the diets were minimal for White Leghorns, whereas for White Rocks there was an almost immediate preference for the balanced diet, followed by lack of preference or preference for the deficient diet.
5. Apparently for some genetic stocks there is rapid adjustment to deficiencies in these amino acids with overconsumption, followed by compensation for preference of the balanced diet. The response, however, will vary depending on the deficient amino acid. 相似文献
2. The EMC was 600 mm wide, 450 mm deep and 450 mm high at the rear; it had a softwood perch and at one side a 250 mm wide nest box (containing litter or artificial turf) with a dust bath direcdy above. It housed 4 birds and provided 675 cm2/bird in the main cage with an additional 281 cm2 /bird in the nest box. The nest box and dust bath had automatically controlled doors which were closed at night. There were 18 EMC; in the first trial these were compared with 6 control cages with perch but without next box or dust bath.
3. Hens spent 32 to 37% of day time on the perch, 5 to 7% in the dust bath and 5 to 6% in the nest. At night 92 to 98% roosted on the perch.
4. Initially only 55 to 70% of eggs were laid in the nest box partly because some eggs were laid before dawn. Once the door was retimed to open 3h before lights‐on the proportion rose to 91 to 96%. Very few eggs were laid in the dust bath. Pre‐laying behaviour lasted longer in treatments with nest boxes (55 to 76min) than in control cages (48min); disturbance was slight in all treatments, but lowest in control cages.
5. Dust baths were well used, with on average 61% of hens dust bathing during a 3‐h afternoon observation period compared with only 17% in control cages. Two birds could use the dust bath simultaneously.
6. It was concluded that although a number of minor design features still required attention the EMC has potential to reduce the disadvantages of conventional cages for welfare while retaining their advantages and has possible commercial application. 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. Liver fat, carcass fat, liver weight and body weight increased markedly at the onset of sexual maturity.
3. Within the liver, the protein to DNA ratio did not alter significantly during development; glycogen was not consistently depleted by egg production.
4. Liver fat content was significantly correlated with carcass fat, liver weight and DNA concentration, and plasma total lipid and cholesterol, independent of stage of development; with body weight, liver protein, moisture, and protein to DNA ratio, excluding the period prior to commencement of sexual maturation; and with plasma phospholipid during lay.
5. Obesity was a feature of faster growing fowls which matured earlier, consumed more, utilised food less efficiently for egg production and produced fewer saleable eggs. 相似文献
2. In both experimental phases birds on treatment 3 produced significantly fewer eggs of smaller mean weight and shell weight. Plasma calcium, inorganic phosphorus concentrations and alkaline phosphatase activity were indicative of decreased calcium status. 相似文献