2. The broilers ate more and grew twice as fast as the layers. They also converted their food more efficiently, partly because they digested their food slightly better than the layers did, but also because their total energy expenditure was probably considerably less than that of the layers. They were very inactive and spent less time feeding, so presumably they could devote proportionately more food energy to growth than the layers could.
3. In the same experiment broiler and layer chicks were reared together in mixed groups, and it was found that each strain affected the other's growth and behaviour slightly. The broilers grew slightly faster in the mixed groups than in the single‐strain groups, whereas the layers grew slightly slower. 相似文献
2. After fumigation with formaldehyde from 40 ml formalin (372 g formaldehyde/1) and 20 g potassium permanganate/m3 for 1 h, no bacteria were recovered from clean eggs by agar plate culture, while a small number of bacteria were detected in three out of five dirty eggs.
3. Average numbers of bacteria detected in clean fumigated eggs were 100.8 to 101.1 during the first 19 d of incubation and 101.2 and 101.4 were recovered on days 20 and 21 of incubation, respectively. At the end of hatching, eggs containing dead embryos were highly contaminated with 103.8 organisms on average.
4. Fluffs of newly‐hatched chicks scattered inside the hatcher were contaminated with bacteria at 104.0 to 108.4 organisms/g. Water in the basin placed in the hatcher and floating fluffs in water were highly contaminated with bacteria. 相似文献
2. After 48 h of food and water deprivation, birds of both species lost about a tenth of their initial post‐hatch weight. Weight loss was more marked in poults subjected to heat stress. Thus, duration of the holding period adversely affected early growth.
3. During the 48‐h holding period, the relative weight of residual yolk decreased in both species by approximately half of its weight in the just hatched chicks and poults. Relative yolk size was much higher in poults than in broilers.
4. On day 1 weight loss was attributed to degradation of the yolk sac, whereas on day 2 only about two‐thirds of the loss could be attributed to residual yolk. Body composition of newly‐hatched broiler chicks did not differ from those held for 24 h despite shortages of energy. However, after 48 h body fat content was markedly reduced compared to newly‐hatched or 24‐h‐old birds.
5. Irrespective of access to food, the relative size of the gastrointestinal tract increased with holding time in both species, reflecting its importance.
6. It was concluded that post‐hatch birds deprived of food and water for 48 h face a severe shortage of energy, causing alterations in body composition. This in turn adversely affects early growth and increases mortality rate under heat stress. 相似文献
2. Birds given a diet containing an increasing proportion of whole wheat supplemented with fresh green vegetable matter (special diet) were compared with conventionally‐fed controls. At 12 weeks of age those receiving the special diet had 10 to 100‐fold higher counts of Escherichia colt and faecal streptococci in the duodenum and lower small intestine and showed differences in the intestinal incidence of species and biotypes of lactobacilli.
3. Evaluation of cooked breast‐meat samples by a trained sensory panel showed a significant difference in flavour (P < 0.01) between conventional and special‐diet birds which varied from perceptually very slight to slight. The main terms used in distinguishing special‐diet birds from conventional controls included ‘richer’, ‘meatier’ and ‘sweeter’.
4. Storage of plucked, uneviscerated birds at 4 °C for 8 d maintained the flavour difference between the dietary groups but the effect of storage on flavour was greater in both groups of birds than the influence of diet alone. The likely influence on flavour of autolytic changes occurring in the muscle during storage of the birds is discussed. 相似文献
2. The rate of lay in both strains was lower in the older hens. The 82‐week‐old hens were subdivided into good and poor layers: the poor layers produced eggs at about half the rate of the good layers.
3. The yellow‐yolky ovarian follicles in both strains were smaller, more numerous and more closely ranked in hierarchies in 26‐week‐old hens than in 82‐week‐old hens.
4. No marked differences were seen between the strains at 26 or 82 weeks of age in the sizes, numbers or hierarchical arrangements of yellow‐yolky ovarian follicles.
5. The ovaries from 82‐week‐old good and poor layers from both strains contained similar numbers of yellow‐yolky follicles.
6. After feeding a fat‐soluble dye, the number of days over which eggs containing dye were laid did not differ between 26‐, 52‐ and 113‐week‐old hens from an egg laying strain. However, fewer eggs with dyed yolks were laid by the older hens.
7. These observations suggest that the decrease in egg production with age is due initially to a reduction in the rate of recruitment of yellow‐yolky follicles. Towards the end of the laying year it may also be due to an increased incidence of follicular atresia, internal ovulation and the production of membraneous or soft shelled eggs. 相似文献
2. Chicks fed on the HPLE diet consumed significantly less food than those fed on the LPHE diet during periods A and B, but not in G. They also produced a significantly larger amount of droppings during periods B and C. Food‐to‐droppings ratio, which was consistently and significantly lower in chicks fed on the HPLE diet, decreased markedly in period C only in these birds.
3. Absolute and relative retention (RR) of dry matter (DM) and starch, and RR of nitrogen (N) from birds fed on the HPLE diet, were consistently and significandy lower than from those fed on the LPHE diet, but fat retention (absolute and relative) was higher. RR of DM and of N in period C was significantly lower than in periods A and B, while RR of fat and of starch was not affected by age. The effect of age on RR of N was observed only with the HPLE diet.
4. AMEn of the HPLE diet, but not of the LPHE diet, in period C was significandy lower than in periods A and B, resulting in a significant interaction between age and diet and a general reduction with age. The calculated AMEn contents of the maize in periods A and B were essentially the same (14.91 and 14.85 MJ/kg, respectively), and lower than in period C (15.28 MJ/kg). It is concluded, therefore, that because of its effect on AMEn of the HPLE reference diet in chicks older than 17 d, bird age is of considerable importance in the determination of AMEn in grains when substituted for the entire diet. 相似文献
2. Birds which received diets containing the exogenous enzymes grew faster for the first 3 weeks but after that there was no apparent difference in rate of growth.
3. β‐Glucanase activities in the crop and small intestine of birds given exogenous enzymes were generally higher than those of birds given only the basal diet.
4. Viscosity of intestinal fluid in birds given only the basal diet decreased with age but there was no corresponding increase in β‐glucanase activity. This discounts bacterial β‐glucanase as a contributory factor in the adaptation to β‐glucanase apparent in older birds. 相似文献
2. TEX-OE® is a patented total extract of the fruit of Opuntia ficus indica, which has been demonstrated to accelerate the development of HSPs in several animal species.
3. One-day-old commercial broiler chicks were treated with TEX-OE®; HSP was measured by enzyme-linked immunosorbent assay (ELISA), and a large commercial field trial investigated key performance indicators (KPIs) in treated versus untreated controls chicks.
4. TEX-OE® significantly increased HSP concentrations in treated chicks versus controls. Final cumulative mortality, liveweight and percentage factory-rejects were better than in controls.
5. The accelerated HSP response may enable chicks to cope with early stressors, which is reflected in improved KPIs. 相似文献
2. The mass of the breast muscles was increased by 10 to 31%, while subcutaneous fat plus skin and abdominal fat pad were reduced by 8 to 23% and 20 to 37%, respectively, in the ducks supplemented 1 to 5 mg CL/kg diet.
3. Increased RNA:DNA ratios in the breast muscle, reduced uric acid and increased free fatty acid concentrations in the serum were observed in clenbuterol‐fed ducks. 相似文献
2. In experiment 1, broilers were grown on 6 experimental diets covering a range from 6.9 to 9.6 g SAA/kg. The diets were fed from 15 to 33 d of age. Similarly, in experiment 2, 6 diets containing 6.0 to 8.5 g SAA/kg were fed to finishing broilers 33 to 43 d of age. In each experiment 60 birds per treatment were processed, and carcase yield and breast meat percentage were determined.
3. Significant responses in weight gain, efficiency of food conversion and breast meat percentage were detected, which could be described well by exponential regression curves. Dietary SAA requirements to obtain maximum efficiency of food utilisation and maximum breast meat deposition were estimated to be about 9.0 g/kg from 15 to 33 d of age, and about 8.0 g/kg from 33 to 43 d of age.
4. Economic aspects were considered to calculate optimum SAA specifications from the results. In both trials, the dietary optimum of SAA was found to be higher for birds to be further processed than for birds to be marketed as whole carcases. 相似文献
2. In all trials fat deposition increased progressively as the protein concentrations of well‐balanced standard finisher diets were lowered by replacing soybean meal with sorghum grains (milo).
3. The increased degree of fatness was the result of graded increases in food consumption, and consequent decreases in food utilisation, caused by inadequate dietary protein.
4. In three out of four trials the above negative trends could be partly or completely reversed by special supplementations with methionine and lysine in amounts to restore the dietary concentration of these first‐limiting amino acids to those of the control diets.
5. It appears that broilers overeat in a compensatory attempt to obtain the limiting amino acids required for optimal growth rate, as long as the deficiency is not severe enough to cause an amino acid imbalance. 相似文献
2. 1,25‐Dihydroxycholecalciferol prevented the tibial dyschondroplasia and rickets caused by feeding a low calcium diet. Gain:food was decreased, but body weight was not affected by feeding 10 μg/kg 1,25‐dihydroxycholecalciferol. Phytate phosphorus retention was increased by dietary 1,25‐dihydroxycholecalciferol.
3. Dietary ascorbic acid did not influence the incidence of tibial dyschondroplasia, but did reduce the incidence of rickets at a dietary concentration of 250 mg/kg. Gakv.food was increased when 250 or 500 mg ascorbic acid/kg diet were added along with 10 μg/kg 1,25‐dihydroxycholecalciferol in one of two experiments.
4. Alkaline phosphatase activity and plasma 1,25‐dihydroxycholecalciferol were not affected by the dietary treatments. Plasma 25‐hydroxycholecalcif‐erol concentration was decreased by dietary 1,25‐dihydroxycholecalciferol.
5. Ascorbic acid had no synergistic effects with 1,25‐dihydroxycholecalciferol on the blood and bone variables investigated in broiler chickens at the dietary concentrations of 1,25‐dihydroxycholecalciferol used in this work. 相似文献
2. Crambe meals were prepared to differ in E‐PG (19, 36 and 40 g/kg) and CHB contents (0.1, 0.7 and 1.9 g/kg), and with either active or inactive thioglucosidase.
3. Meals were fed to 7‐d‐old broiler chicks at 50 or 100 g/kg of the diet for 12 or 13 d. In separate studies, isolated E‐PG or CHB were mixed into the diet or administered by gavage to 7‐d‐old broiler chicks in amounts equivalent to 50 or 100 g/kg crambe meal diets for 10 and 12 d, respectively.
4. Weight gain decreased (P<0.05) in chicks fed on the high glucosinolate crambe diets or isolated E‐PG. Food consumption decreased (P<0.05) in chicks fed on the diet containing the high E‐PG meal with active enzyme.
5. Mild liver lesions and increased serum aspartate aminotransferase were found in chicks fed on the diet containing the high glucosinolate meal with active enzyme. Other organs, including thyroids, were normal.
6. Commercially‐processed crambe meal appeared safe at an inclusion rate of 50 or 100 g/kg diet, but could not be recommended at this point for long term feeding. 相似文献
2. In the first week after trimming, when trimmed birds were compared with untrimmed controls, they were less active (sat and slept more), fed less, preened less and generally engaged in less beak‐related behaviour.
3. These differences waned sharply during week 2 and had disappeared by week 5. There were very few differences between hot‐ and cold‐cut birds.
4. There were also differences in production variables: trimmed birds grew more slowly during the week after trimming, their food intake was depressed for 3 weeks and food conversion efficiency improved for 2 weeks.
5. The only significant effect on feather scores was better plumage condition in the groups trimmed at 1 d and scored at 6 weeks.
6. To examine the anatomical effects 36 ISA Brown chicks trimmed by hot or cold cut at 1 d or 10 d of age were killed at 21 and 42 d after trimming, and their beaks were processed and examined histologically. In all trimmed groups healing was very rapid and no scar tissue was seen but, unlike the controls, the regrown tips contained no afferent nerves or sensory corpuscles.
7. Beak lengths immediately after trimming were 40% to 50% shorter than controls; the anatomical consequences of both methods were identical.
8. Overall, it was judged that the effects on behaviour and beak anatomy were much less severe than previously reported for birds trimmed at older ages. If birds do have to be trimmed then the procedure should be carried out in young birds: from the birds' standpoint 1 d appears to be the most suitable. 相似文献
2. In experiment 1, replacing 75 μg cholecalciferol/kg with the same weight of 25‐HCC decreased significantly (P<0.01) the incidence of TD from 65 to 10%.
3. In experiment 2, the incidence of TD in the control group was lower, but feeding amounts of 25‐HCC up to 250 μg/kg had a linear effect on the incidence of TD that was significant at P=0.06. There was no effect or interactions with dietary addition of 250 mg ascorbic acid/kg. Dietary addition of 5 μg 1‐HCC/kg decreased TD incidence from 21 to 5%, though the effect was not significant (P>0.1).
4. TD incidence in experiment 3 was too low to determine an effect of 25‐HCC or 1,25‐DHCC on TD incidence, though in this, as in both other experiments, the severities of TD lesions were always lower with diets containing cholecalciferol metabolites.
5. Hypercalcaemia was not observed after feeding up to 250 μg 25‐HCC/kg in either experiments 2 or 3.
6. It is concluded that 25‐HCC may be an effective practical means of improving broiler leg health by alleviating the incidence and severity of TD. 相似文献