2. Approximately half of the flocks were fed on either a high (163 mg/kg) vitamin E or on a normal (44 mg/kg) vitamin E‐containing diet throughout production.
3. Approximately half of the flocks were the progeny of breeder flocks which had been fed on a high vitamin E‐containing diet throughout production.
4. The improvement in target income in the vitamin E‐supplemented broiler flocks was 8–44% (P < 0.01).
5. The residual improvement in target income in these flocks, after the cost of the additional vitamin E was taken into account, was 2.74% and failed to reach statistical significance.
6. The increased net income was achieved by a significantly improved food conversion ratio and average weight per bird (P < 0.05).
7. There was no overall effect of vitamin E supplementation of broiler breeders on subsequent broiler performance. 相似文献
2. After feeding RSM, hepatic TMA oxidase was very low (P < 0–001) in one group (sensitive) but was unaffected in the other group (resistant). Thyroid size was increased in both groups receiving RSM but was larger (P<0–001) in sensitive birds.
3. Plasma half life of thyroxine (T4) and its metabolic clearance rate were not affected by feeding RSM; thyroidal secretion was reduced (P < 0–05) to the same extent in both groups.
4. Plasma concentration of triiodothyronine was decreased in both groups after feeding RSM (P<0–05); plasma T4 concentration was increased (P<0–05) only in sensitive birds.
5. The results indicate that the short‐term depression of TMA oxidation in birds sensitive to RSM is not mediated by the thyroid. 相似文献
2. Ligation of the caeca significantly improved nitrogen balance and utilisation by up to more than 2 times as much as those of controls (P< 0.05).
3. The treatment significantly decreased uric acid excretion by 77 mg nitrogen/day (P< 0.01) and also total nitrogen excretion (P<0.05): the former decrease almost explained the latter.
4. No effect of the ligation of caeca on urea and ammonia excretion was observed.
5. It is concluded that nitrogen metabolism in chickens is affected by possible changes in caecal fermentation by preventing entry into the caeca of substances from urine and digesta. 相似文献
2. The data conformed to a mixed model and adjustments were made for the fixed effects sex, hatch date and location. Adjustment improved the precision of the estimates by reducing the error variances significantly.
3. Rearing equal numbers of birds from each family at different locations made the interactions negligible.
4. Weight gain was greater if illumination intensity up to 35 d was less.
5. Females were not heavier on the 1st day but were heavier on the 14th and 35th days than males.
6. Variance components and genetic parameters were estimated. 相似文献
2. Substituting triticale for maize, weight for weight, but not on a iso‐nitrogenous basis, in a groundnut oil cake (GNC) starter diet improved weight gain (P < 0.05) when the substitution exceeded 75% without affecting the protein efficiency ratio (PER).
3. A similar substitution in a soybean oil meal diet, improved weight gain (P < 0.05) at 50% or more but PER declined (P < 0.05).
4. The net protein utilisation and protein retention efficiency values of the diets in which maize protein was replaced by triticale protein were significantly reduced.
5. The maize‐GNC diet was equally limiting in methionine and lysine while the triticale‐GNC diet was not.
6. The growth and food efficiency obtained with a triticale‐GNC diet was higher (P < 0.01) than with the maize‐GNC diet but not with a maize‐GNC supplemented with fish meal and methionine.
7. It is concluded that triticale could quantitatively substitute maize in the starter diets. 相似文献
2. The taint was due to the inclusion of either 25 or 70 g Icelandic capelin fishmeal/kg of the diet.
3. Babcock hens produced significantly more (17%) tainted eggs than Warrens (1.2%).
4. Tainted eggs were significantly reduced to a very low proportion (1.3%) by the third day of feeding a fishmeal‐free diet.
5. The taint was due to the presence of up to 17 mg/trimethylamine kg in affected eggs. 相似文献
2. Using one of these methods a survey was conducted on eggs which had failed to hatch from commercial hatcheries.
3. An assessment of the level of contamination in the eggs examined indicated an average level of contamination of 12.7%.
4. The contaminating flora was composed mainly of Micrococcus sp. and Enterobacteriaceae, with Streptococcus sp., Staphylococcus sp., Bacillus sp. and Pseudomonas sp. present at lower levels.
5. Various interrelationships between contamination and hatchability are discussed. 相似文献
2. The inclusion of low glucosinolate RSM (100g/kg) in the diet did not affect egg production adversely. Inclusion at a rate of 125 or 150 g ‘ of this type of meal per kilogram resulted in non‐significant reductions in egg production when compared with that of the birds fed on the control diet.
3. Egg weight, specific gravity and Haugh unit values were unaffected when low glucosinolate RSM was included at rates of up to 150 g/kg whereas inclusion of high glucosinolate RSM at the rate of 100 or 150 g/kg decreased egg production and Haugh unit values when compared with the results obtained from a control diet based on soyabean meal.
4. Thyroid glands were slightly enlarged when low glucosinolate RSM was included in the diet at concentrations up to 150 g/kg, while 100 or 150 g high glucosinolate RSM/kg caused marked enlargement in thyroid glands.
5. None of the treatments affected liver weight, spleen weight, composition of liver, liver fat score or the incidence of haemorrhagic liver syndrome. 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
(i) The heritability of weight gain declined sharply with age over consecutive periods after 12 weeks. The genetic correlation of body weight at 12 weeks with gain in subsequent periods was low. There appeared to be sufficient genetic variance in growth rate in these later periods to alter the growth curve substantially by selection. For example, it should be possible to breed strains with a rapid early growth and low mature body size.
(ii) There was evidence of genetic variation in the change of egg weight with time. The genetic variation was, however, so low that in any selection programme to improve 28‐week egg weight without changing 44‐week egg weight the progress would be very slow.
(iii) Body weight at 12 weeks was genetically negatively correlated with sexual maturity. Its correlation with production in the first 44 weeks was positive in both strains, but not significantly different from zero.
(iv) Body weights after 28 weeks were apparently uncorrelated with egg production or sexual maturity.
(v) Egg weight and production traits show considerable heterogeneity of variance between years, probably partly due to their distribution not being normal.
(vi) The pattern of genetic variation appeared to differ significantly between the two strains so that correlated responses would not necessarily be the same.
(vii) There was a suggestion of maternal effects acting upon body weight but the evidence was somewhat contradictory and inconclusive due to the high standard error of the estimates.
(viii) None of the 15 traits measured regressed over the 3 year period of relaxation of selection. 相似文献
2. Live‐weight gains, from 8 to 63 d, were depressed when the diet contained 150 g RSM/kg and there was a highly significant negative correlation between weight gain and inclusion rate of RSM over this period.
3. The efficiency of food utilisation was worse when the diet included 150 g solvent RSM/kg than when it contained no RSM: food efficiency was consistently poorer whenever RSM was included in the diet but the difference was significant only when the diet contained 10 g tallow/kg.
4. Carcasses from birds fed on diets containing 10 g tallow/kg had a better appearance than those from birds on diets containing 30 g tallow/kg, while the flavour of meat from birds fed on a diet containing 150 g solvent RSM/kg treatment was adversely affected. However, up to 100 g solvent RSM/kg may be included in broiler diets without affecting appearance, taste, texture or acceptability of the meat.
5. Inclusion of 50 g or more, solvent RSM/kg reduced growth rate and worsened food efficiency. 相似文献
2. An Individual Poultry Weighing System (IPWS) was developed to record time, duration, location and body weight of visits of individual hens to 4 weighing scales.
3. The number of hens that visited the weighing scales per 3 h period varied from less than 10 during the dark‐period to more than 60 during the light‐period.
4. The average number of visits per individual hen was 1–4 and the average number of successful weighings per hen was 0–6 during the light‐period.
5. Body weight showed a diurnal rhythm: the difference between the maximum body weight at night and the minimum body weight in the morning was 63 g.
6. The location of the scales influenced number of visits, number of weighings, mean body weight, flock‐uniformity and duration of visits.
7. Body weight per 3 h period did not differ between hens which were individually recognised and those which were not.
8. Flock‐uniformity was 2–6% higher during the light‐period if it was based on weighings of identified hen visits.
9. The average duration of the visits to the scales in the middle of the feeding tier during the light‐period was 63 s.
10. Of all the hens that visited the scales during a 24 h period, 54% visited them only once.
11. Automatic weighing systems without individual hen recognition can deliver reliable management information on mean body weight and flock‐uniformity in aviary systems if the weighing scales are located on the feeding tier in the middle of the house and if they are used during the light‐period. 相似文献
2. Very large egg batches are required to detect small improvements in the hatchability of good hatching strains.
3. Small‐scale laboratory studies on hatchability are best confined to strains and species of low hatchability in which larger between‐treatment differences may be expected.
4. The results of hatchability studies should always be subjected to tests of statistical significance.
5. There is a strong case for studying continuous variates in the laboratory before proceeding to large‐scale hatchability studies. 相似文献
2. Food intake and food conversion ratio were greater (P<0.05) in the F line than in the E and C lines.
3. Metabolisability of the diet was 0.8% higher in the E line than in the other lines.
4. Metabolisable energy (ME) intake and heat production were greater (P<0.05) in the F line than in the E and C lines, and energy balance was greater (P<0.05) in the F than in the W and E lines.
5. During starvation, excreta energy and heat production were greater (P < 0.05) in the F than the other lines.
6. Availability of ME (net energy) was the same (85%) for all lines but calculated daily maintenance energy requirements (kJ ME/kgW) were W, 860; F, 937; E, 796 and C, 810.
7. By 9 weeks the F line contained more fat and less water than lines E and C. 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. The volume of water taken up by eggs that had been sanitised was significantly (P < 0.001) greater than that taken up by the control eggs. The volume of water taken up by the sanitised eggs increased as the flock age increased, whereas water uptake was maximal for the control eggs at 42 weeks of age.
3. There was no correlation between water uptake values and shell thickness or egg weight for either the sanitised or control eggs.
4. Sanitised eggs tended to dominate the “poor cuticle quality” category at all flock ages, when a subjective assessment of cuticle quality was made using the stain Edicol Supra Pea Green.
5. Egg sanitising did not affect shell reflectance values, shell thickness or the percentage of cracked shells.
6. When flock age reached 49 weeks of age, the sanitising process significantly (P < 0.001) reduced hatchability. 相似文献
2. Myofibrils were prepared from 0.1 M and 0.2 M lactic acid marinated muscle and control (non‐marinated samples) sampled at 0, 1, 3, 7 and 14 d post mortem.
3. Changes in myofibril fragmentation index (MFI), myofibrillar proteins and Z‐line structure were examined.
4. Marination of duck breast muscle in lactic acid at 5°C enhanced fragmentation of myofibrils and degradation of myofibrillar proteins and Z‐line structure as compared to control samples.
5. In summary, lactic acid marination at 5°C can accelerate the post mortem degradation of myofibrils in Tsaiya duck breast muscle. 相似文献
2. Changes in plasma cholesterol were equivocal, though there was perhaps a trend towards hypercholesteraemia.
3. Birds became hypoglycaemic within an hour but were hyper‐glycaemic between 2 and 4 h. At 24 h they were normoglycaemic.
4. Plasma corticosterone was increased markedly at 1 h but was decreased compared with the control at 2 h (P<0.01). Thereafter the concentration was in the normal range.
5. There was an enhanced hyperlipacidaemia in the treated birds after 1 h.
6. Adrenal cholesterol stores were decreased by 10% at 4 h but were unaffected at all other times.
7. Colonic temperature decreased by 1–6 °C after 2 h but was normal by4h.
8. It is concluded that propranolol has mild stressor activity which is lost within 24 h. 相似文献
2. Peptide maps of cyanogen bromide‐cleaved ovomucoids from Muscovy duck and domestic duck were very similar to one another, but differed from that of goose.
3. Muscovy duck ovomucoid showed the same protease inhibitory pattern as ovomucoid from domestic duck, inhibiting trypsin in the molar ratio of 1:2 and chymotrypsin 1:1.
4. Inhibitory complexes could be detected between chymotrypsin and ovomucoid from both Muscovy and domestic duck, but not from goose, by using non‐denaturing gels.
5. No complexes could be detected between DFP‐inactivated chymotrypsin and any of the ovomucoids.
6. The results show that of ovomucoid from Muscovy duck more closely resembles that from domestic duck than goose. 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