2.?White, 1-d-old, Hy-Line hybrid chicks (n?=?840) were divided into 4 main groups, each comprising 7 replicates of 30 chicks (n?=?210): (1) control; (2) 1000?mg/kg yeast cell walls (YCW) added; (3) 1000?mg/kg Yucca schidigera extract (YE) added; and (4) 500?mg/kg YE?+?500?mg/kg YCW added. The trial lasted 60?d.
3.?Daily weight gain of the chicks was positively affected between d 45-60 in the YE and YCW?+?YE groups compared with the control group.
4.?Overall, feed consumption did not differ between the control and YCW, YE, YCW?+?YE groups during the 60?d study period. Feed efficiency was better in the YE and YCW?+?YE groups than in the control group between d 1-60.
5.?During the 60?d evaluation period, live weight gain, and final live weight were higher in YE and YCW?+?YE groups than in the control group.
6.?Antibody titres against infectious bronchitis and infectious bursal disease did not differ among the 4 treatments, but those for Newcastle disease were higher in the YE?+?YCW groups than in the control, YCW and YE groups on d 45.
7.?There were differences in intestinal histomorphometry between the 4 treatments. The height of the jejunal and ileal villi was greater in the YE and YCW?+?YE groups than in the control and YCW groups
8.?It can be concluded that YCW and YE supplementation for layer chicks is beneficial for growth performance and intestinal histology during the 1-60?d growing period. 相似文献
2. Higher rates of fertility and hatchability of Japanese quail eggs were observed from parents of 10 to 19 weeks of age, with peak fertility and hatchability at 14 and 12 weeks of age, respectively.
3. Sex ratios of 1:2 to 1:5 gave comparable fertility and hatchability results.
4. The hatching performance of quail eggs from cage and deep litter reared breeders was comparable.
5. Fertility and hatchability were directly proportional to the egg weight.
6. Quail egg shell colour, tints and blotches were found to influence hatching performance.
7. Storing quail eggs at 16 ± 2°C and 75 ± 5% relative humidity for more than 4 d reduced hatchability.
8. Hatchability of eggs stored at room temperature was improved if they were sealed in polyethylene bags.
9. Provision of light during the first 14 d of incubation resulted in a photo‐acceleration of about 3.2 h. 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. Microbial strains for the efficient elimination of uric acid were isolated.
3. Suitable, cheap carbon sources (methanol, glycerol, glucose) were tested in attempts to increase cell yield.
4. These criteria were used to study the 41 bacterial and 8 yeast strains which were the most prolific on slants and which were isolated from experiments with a shaker. A strain was selected for experimentation with a fermentor.
5. Fermentor experiments were done on a laboratory scale (101) and in a non‐sterile semicontinuous system (150 1), cell mass production being similar in both systems. 相似文献
2. Rocking embryo cultures during the first half of incubation enhanced embryo growth.
3. Embryos explanted into ‘surrogate’ eggshells of either other individuals or other species have been successfully ‘hatched’.
4. A normal chorioallantois is formed in these surrogate eggshells. This enables a functional albumen sac to form and eggshell resorption to be achieved.
5. Embryos grown in ‘surrogate’ eggshells are slightly smaller than controls but otherwise normal.
6. The technique provides opportunities for genetic engineering experiments. 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
2. The difference between the NPU values, 0.66 for yeast and 0.80 for the soyabean meal and fish meal mixture, could largely be attributed to the high nucleic acid content of the yeast.
3. Chicks given the diet containing yeast (190 g/kg) did not grow as rapidly as those given the soyabean meal and fish meal reference diet, and the reduced growth could only partly be explained by a marginal deficiency of methionine.
4. Food conversion efficiency with the yeast diet was improved by maize oil while responses to α‐tocopheryl acetate and sodium selenite were inconsistent.
5. Chicks grew well when yeast replaced fish meal in the mixture of soyabean meal and fish meal, and when fish meal (194 g/kg diet) was the sole protein supplement. 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. Hens of the population with the high incidence of whitening appeared to be more fearful than hens of the population with the low incidence of whitening.
3. Brown colouration of the egg shell and the incidence and degree of shell whitening declined as the hens aged.
4. Brown colouration and egg shell whitening were most pronounced on the blunt ends of the eggs.
5. A large part of the variation in egg shell whitening was attributable to the individual (hen) component of variance.
6. Differences in egg shell whitening, between the two populations, were detectable throughout the 26 weeks of the experiment.
7. Oviposition intervals were similar for normal and coated eggs when birds were not exposed to disturbance.
8. Disturbance of hens increased oviposition intervals and the incidence and degree of shell whitening, to a similar extent, in both populations.
9. It is concluded that stress‐related egg retention is not the sole factor responsible for abnormal egg shell whitening. Shell whitening may occur as a consequence of the premature termination of shell pigmentation as well as a consequence of the retardation of oviposition which occurs when hens are disturbed. 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. Photoperiod treatments consisted of computer simulations of day lengths which occur naturally in the spring and autumn of the year. Both photoperiod treatments were given to hens in the autumn and spring.
3. Data were collected for growth evaluations at 2‐ to 4‐week intervals to 16 weeks of age. No significant season × photoperiod interactions occurred.
4. The spring trial resulted in greater body weights and better food conversions (food/gain) than the autumn trial.
5. Simulated autumn daylengths resulted in greater body weights and improved food efficiency at 16 weeks of age compared with simulated spring daylengths.
6. The pattern of growth (period changes) was influenced by season, but not photoperiod.
7. Season and photoperiod both have important and independent influences on the growth of the turkey hen. 相似文献
2. It was fed at 16 weeks of age to five separate groups (groups 2 to 6) each of 50 to 60 birds.
3. Group 2 was fed on a normal layers’ diet at 23 weeks of age, group 3 at 27 weeks, group 4 at 31 weeks, group 5 at 35 weeks and group 6 at 55 weeks while the control group (group 1) of similar size to groups 2 to 6 was subjected to a normal commercial treatment for laying stock.
4. In all the experimental groups the onset of sexual maturity occurred normally, but only one or two eggs were laid before laying ceased under the influence of the treatment.
5. Laying re‐started when the hens were fed on a normal diet and production rapidly rose to a high level.
6. Groups 1, 2 and 3 differed little in the total number of eggs produced up to 72 weeks of age.
7. In all experimental groups there were fewer very small, small and medium eggs than in the control group.
8. It is suggested that the use of a low‐calcium diet before the onset of lay may have advantages which could be exploited on a commercial scale. 相似文献
2. Xylanase supplementation improved food conversion ratios by 2·2–2·9% and body weight gain by 0·2–2·5%. This was independent of wheat characteristics but slightly dependent on the wheat content of the diet. These effects were related to a lowering of digesta viscosity.
3. Differences in extract viscosity of wheat were not reflected in broiler digesta viscosity.
4. Reduction of digesta viscosity resulted in only a slight improvement of litter score. Reduced intestinal viscosity decreased relative pancreas weight and to a lesser extent relative small intestinal weight.
5. Baking quality wheat Baldus gave better performance than the feed quality wheats Apollo and Slejpner.
6. It was concluded that xylanase supplementation of wheat‐based diets invariably had a positive effect on broiler performance. 相似文献
2. Reactivity of CD3 antiserum in chicken intestine was very good.
3. Increased numbers of epithelial lymphocytes as well as infiltration of CD3 cells into the lamina propria were demonstrated.
4. Intestinal homogenate caused impaired growth and bad feathering in broiler chickens until 21 d of age. 相似文献
2. The response in shell thickness to ahemeral lighting was more rapid (2.2 d) than for egg weight (4.2 d).
3. Differences between genotypes were evident in both the speed and magnitude of response.
4. Overall, egg weight and shell thickness on the 28‐h cycle were 7% and 8% greater than on 24 h.
5. The allometric increase indicates that the increase in shell weight was on average 14% more than the increase in egg weight. 相似文献
2. Replacing groundnut oil cake (GNC) by Niger oil cake (NC) on an isonitrogenous basis, did not affect egg production, egg weight or the amount of food required per dozen eggs.
3. The percentage retention of nitrogen from diets containing 30% GNC or 30% NC was similar.
4. The ME value of NC used was 3025 kcal/kg.
5. It is concluded that NC can replace GNC in layers’ diets. 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. Oiling slowed the decline in albumen height (Haugh units) to that which occurred in unoiled eggs stored at 12 °C.
3. Oiling slowed the increase in albumen pH equally at 28 and 12 °C.
4. Oiling markedly decreased the weight loss of eggs stored at either temperature.
5. Oiling and temperature of storage were without effect on the whipping volumes of either albumen or unseparated albumen and yolk. 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. Deformation was not completely reversible due to crumbling at the points of contact with the force.
3. There are three components of non‐destructive deformation: (a) local deformation at the points of contact, (b) local surface crumbling and (c) deformation of the over‐all shell structure.
4. The latter two are uncontrolled, contributing to errors in the prediction of fracture force and depending on the non‐destructive force applied.
5. These effects should be considered in test selection and interpretation.
6. The optimum non‐destructive force was found to be 1 kg. 相似文献