2. Time of day of injection did not modify the response to corticosterone of 3‐week‐old chicks kept under natural daylight nor of 7‐week‐old broilers receiving additional illumination.
3. Pure White Rock chicks and Cornish x White Rock crossbred chicks responded similarly to corticosterone injections at 3 weeks of age.
4. Seven‐week‐old female birds treated with corticosterone had significantly larger abdominal fat pads than similarly treated males.
5. Corticosterone injection was more effective in increasing the proportion of liver fat in 7‐week‐old birds than in 3‐week‐old ?hicks.
6. The increased amount of abdominal and liver fat due to corticosterone injections administered at 3 weeks of age disappeared after 3 weeks, but growth depression was still evident. 相似文献
2. In each group of birds the concentration of plasma GH was inversely related to age. The mean prolactin concentration was highest in the youngest (20‐d‐old) birds.
3. The concentration of plasma GH in the intermittently‐fed birds deprived of food for 24 h (depleted birds) was significantly higher than that in the controls at 33, 56 and 83 d of age. The mean GH concentration in the intermittently‐fed birds 24 h after refeeding (repleted birds) was less than that in the depleted ones.
4. The overall mean concentration of plasma prolactin in the depleted birds was significantly less than that in the control and repleted birds.
5. These results are consistent with the effects of fasting on GH and prolactin secretion and demonstrate that growth retardation in the intermittently‐fed birds was not due to impaired GH secretion. 相似文献
2. Restricted birds were lighter throughout the experiment.
3. Relative adrenal weight tended to be greater in restricted birds but the difference decreased with time.
4. There was no depletion of adrenal cholesterol: from week 5 there was a significantly greater amount in the adrenals of restricted birds.
5. After 1 week of restriction plasma corticosterone concentration was 73% greater than in controls. It decreased progressively, falling within the normal range at 5 weeks.
6. Restricted birds were hypoglycaemic from weeks 2 to 7 and hyper‐lipacidaemic throughout. A negative correlation between plasma glucose and free fatty acids was found. 相似文献
2. Environmental enrichment improved body‐weight gain, relative body‐weight gain and gain: food ratio but had no effect on circulating GH or prolactin concentrations.
3. Weight gain and gain : food ratio were greater in the broilers than in the layer chicks, while plasma GH and prolactin (females only) concentrations were less.
4. There were no sex differences in weight gain and relative weight gain but gain : food ratio was significantly greater in females than in males. In both strains plasma GH concentrations were higher in males than in females and prolactin concentrations were higher in male than in female broilers. 相似文献
2. Although the protein content of all tissues varied with age, the only statistically significant effect was on the level of protein in the gizzard.
3. The moisture content of the gizzard was significantly affected by age and blood by age and sex.
4. The fat content of the gizzard was significantly affected by age, as was the effect of sex on the fat content of blood.
5. The ash contents of heart and gizzard were significantly affected by age.
6. The phosphorus contents of the gizzard, heart and liver were significantly affected by age, as were the chloride content of heart and the calcium content of the liver. Blood potassium was significantly affected by sex. Fluctuations in the contents of other elements are discussed.
7. The variability in organ composition is discussed with respect to the degree of trimming and preparation of the samples. 相似文献
2. Protein and energy metabolism were studied in males from these selected lines fed on a diet of intermediate protein content.
3. All selected birds retained more nitrogen than those studied 10 years previously.
4. There was no difference in nitrogen retention between groups, although relative growth rate of group B birds was higher.
5. Heat productions relative to gross energy intake were 0.38 (group B) and 045 (group A). Energy retentions relative to gross energy intake were 0.39 (group B) and 0.35 (group A); the difference being primarily due to higher fat retention in group B.
6. Using a common maintenance requirement for metabolisable energy, group B utilised metabolisable energy for growth (0.78) better than did group A (0.71).
7. At 53 d of age plasma glucose (10%) and insulin (50%) were higher in group B than in group A. 相似文献
2. Half the hens had undergone beak trimming at 18 weeks, but in many cases regrowth had occurred.
3. Plumage damage and loss was significantly reduced in beak‐trimmed birds compared with birds with normal beaks. Tier and cage design had no effect.
4. This finding supports the idea that feather pecking is the important factor in causing plumage damage, rather than abrasion.
5. A comparison between 64 birds in which beak regrowth had occurred, and 64 in which it remained truncated, showed that both groups had similar plumage scores.
6. It appears to be the beak‐trimming procedure which is important; subsequent regrowth being irrelevant. 相似文献
2. A randombred control population of known pedigree was used to measure the environmental trends.
3. Selection in pure lines resulted in concomitant improvement in the crosses for the selected as well as the correlated traits.
4. Cross performance was comparatively more than expected on the basis of mid‐parent values, indicating involvement of non‐additive gene action in the expression of cross performance.
5. Crosses responded better to independent culling level selection for egg weight than their parents.
6. Heterosis appeared to increase in later generations as compared with initial generations of selection. 相似文献
2. A circadian system was postulated to control the restriction of ovulation to an 8‐h period of the day under conventional 14 h light: 10 h dark regimes.
3. The final phase of follicular maturation was postulated to commence after ovulation of the preceding ovum in the hierarchy.
4. Ovulation was postulated to occur when a mature follicle was present in the ovary during the appropriate phase of the circadian‐linked system.
5. The predicted times of oviposition were within the standard error of the observed times of oviposition under 21‐, 24‐ and 28‐h photoschedules.
6. It was concluded that this hypothesis for the control of the ovulatory cycle of the hen is consistent with current knowledge. 相似文献
2. In 4 consecutive trials, 4752 hens were recorded for keel bone status. Evaluation of plumage condition was made for 1440 hens and bone breaking strength was recorded for 1200 hens. A total of 4962 eggs were analysed for internal and external egg quality traits. Analyses involved 30 small group compartments per trial.
3. The layer line had a much more pronounced influence on humerus breaking strength than on tibia breaking strength.
4. Plumage condition, particularly on the neck, was positively correlated with humerus breaking strength in both layer lines.
5. An average of 34% of LB and 23% of LSL hens showed keel bone deformities, with higher proportions of slight deformities.
6. Slight keel bone deformities, rather than moderate to severe, increased significantly during the laying period.
7. Stocking density had no influence on bone breaking strength, keel bone status and egg quality traits.
8. LB layers had a 1.4-fold higher humerus, but only a 1.06-fold higher tibia breaking strength compared to LSL layers.
9. Tibia breaking strength was significantly affected by the interaction of group size and layer line. LSL layers in small groups had lower tibia breaking strengths than those of the large groups. 相似文献
2. Dry plucking increased weight loss due to plucking and eviscerating, and reduced chilled carcass yield.
3. Dry eviscerating increased carcass water uptake during chilling.
4. Pre‐chilling with running water increased carcass water uptake compared with chilling in ice and water alone.
5. Water uptake during chilling appeared to be increased by longer eviscerating time. 相似文献
2. Intra-abdominal (IA) injection of LPS significantly suppressed feeding behaviour and significantly increased mRNA expression of IL1β and IL8 in the diencephalon when compared to the control group, while IL6 tended to be increased.
3. Intracerebroventricular (ICV) injection of 200 ng IL1β significantly decreased food intake at 60 min after the injection while IL6 and IL8 had no effect.
4. IA injection of these ILs (200 ng) had no effect on food intake in chicks.
5. ICV injection of 200 ng IL1β did not affect water intake and plasma corticosterone concentration, suggesting that central IL1β might not be related to the regulation of drinking behaviour and the hypothalamus–pituitary–adrenal axis.
6. The present study demonstrated that central IL1β but not IL6 and IL8 might be related to the inhibition of feeding in 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
2. The different varieties of wheat investigated contained different proportions of water‐soluble to water‐insoluble hemicelluloses.
3. By comparison of the arabinose to xylose ratios it was concluded that water‐soluble and insoluble arabinoxylans of wheat were branched to the same degree.
4. Starch from six wheat varieties grown in the U.K. was very well digested by adult cockerels and true metabolisable energy values of the wheats were high.
5. Small amounts of cell wall carbohydrates were digested by adult cockerels. 相似文献
2. A comparison with an unselected control flock (C) over 50 weeks of lay in the final generation indicated a number of statistically significant correlated responses in commercially important traits in the S line in addition to the direct response of + 0.004 in specific gravity.
3. With an increase in specific gravity, there was a decrease of 3.4 in the percentage of soft‐shelled eggs laid.
4. The weight and albumen height of eggs measured within 1 hour of lay declined by 1.8 g and 2.1 Haugh units respectively.
5. There were reductions in the weight and albumen height losses of eggs stored over a 10‐d period (C 0.74, S 0.62 g and C 17.9, S 15.0 Haugh units respectively), so that at the end of this period the albumen heights in both lines were the same.
6. Average body weight and daily food intake were less by 0.28 kg and 7.5 g respectively.
7. Although there was no change in egg production, the average age at first egg was reduced by 11.3 d. 相似文献
2. The poults were free from contamination on arrival at the rearing house but were contaminated via the water supply from troughs which had been ineffectively fumigated.
3. Foodstuffs did not appear to be a source of contamination.
4. The spread of salmonellae in this turkey rearing enterprise was very similar to that in chicken rearing houses. 相似文献
2. The Na and water contents of skeletal muscles were increased by TA treatment while K was unaltered.
3. The extracellular space expressed as a proportion of starved body weight was unaffected by TA implantation.
4. Plasma or serum concentrations of P, Ca, Mg, Na and K and activities of the enzymes aspartate aminotransferase [EC 2.6.1.1], creatine kinase [EG 2.7.3.2] and γ‐glutamyl transferase [EC 2.3.2.2] were not changed by TA treatment.
5. Packed cell volume was significantly increased by TA implantation after a delay of some 2 to 3 weeks while plasma protein concentrations were immediately decreased for a period of two weeks before nearly normal concentrations were obtained again.
6. Erythrocyte sedimentation rate was decreased by TA treatment, but serum protein electrophoretic pattern was unchanged. 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. Reduction in the duration of illumination did not impair growth rate.
3. The sexes showed a differential response to the treatments.
4. There was evidence that the enhanced performance of females was due to an improvement in food conversion efficiency. 相似文献
2. The water content was highest in White Leghorn eggs, which were the heaviest.
3. Cholesterol content was similar in all eggs except for Dwarf Sussex in which it was less.
4. English Gamecock eggs contained a higher proportion of protein than those of the other breeds.
5. From the data presented, egg size, under similar conditions of feeding, does not determine the contents of components of the egg, but there are underlying genetic factors. 相似文献