2. Selection for increased growth was practised for two generations using ten females and five males as parents in each line.

3. A significant interaction between time and temperature was observed in the third generation progeny; when exposed to heat stress, the stress‐adapted lines showing a superior growth rate.

4. A sex × temperature interaction was also observed and was due largely to the control females being more sensitive to stress than the males.

5. A cumulative realised heritability estimate of 0.47 ± 0.15 for 5‐week body weight was obtained.  相似文献   

2. Realised heritability estimates calculated after five generations of selection were : 0–37 + 0.04 for weight gain (WG); 0.44 + 0.05 for food consumption (FC); 0.21 + 0.04 for food conversion ratio (FCR).

3. Realised genetic correlation estimates were: WG and FC, +0.71 ±006; WG and FCR, ‐0.40±0.09; FC and FCR, +0.27 + 0.09.

4. Zero‐generation heritability and genetic correlation estimates were greater than the realised estimates, and sex linkage appeared to be important in the expression of all three traits.

5. The genetic correlation between FC and FCR was asymmetrical with considerable positive response in FCR in line F (r_g = +0.79) but negligible response in FC in line E (r_g = —0.01).

6. There was an apparent plateau in response in FCR in line E from the third to the fifth selected generations.  相似文献   

2.?Fifty-eight laying hen farms in France were studied, including 21 flocks housed in conventional cages, 7 in furnished cages and 30 kept on-floor.

3.?Sixty eggs per flock were analysed to obtain counts of the total mesophilic flora. Data on equipment and hen management were collected.

4.?Mean bacterial count on eggshells tended to be higher in on-floor systems (4·82 ± 0·51 log CFU/eggshell) than in cage systems (4·57 ± 0·58 log CFU/eggshell, P = 0·09).

5.?Contamination increased with age of the hens, airborne dust concentration, manual packing of the eggs, and packing in plastic rather than in recycled-pulp egg-flats.

6.?The effect of the housing system on eggshell contamination, previously described in experimental assays, was confirmed under production conditions.  相似文献   

2. Differences (P < 0.05) in growth existed between sexes. Mature mass values of 148.0 ±3.00 and 191.9 ±5.35 g respectively were found for males and females. Males reached maximum growth at 13.4 ± 0.33 d while a value of 16.4 ± 0.46 d was found for females.

3. A plateau in daily food intake was reached when the time of mature mass was approached.  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. Fertile eggs (n = 150) were injected into the air sac or yolk sac with 0.5 ml normal saline solution or normal saline and pure RJ. The eggs were randomly divided into 5 groups of 30 eggs each: NC, control eggs receiving no injection; ASA, air sac–injected eggs given normal saline solution; ARJ, air sac–injected eggs injected with pure RJ; YSA, yolk sac–injected eggs receiving normal saline solution and YRJ, yolk sac–injected eggs given pure RJ.

3. Injection of RJ significantly decreased hatchability (46.7%) compared with injection of saline solution (68.3%). Hatchability was lower in ARJ (33.3 %) and YRJ (60.0%) groups than in the NC group (90.0%). Hatchability in ASA (70.0%) and YSA (66.66%) groups were comparable to the NC group.

4. In ovo injection of RJ into both sacs increased chicks’ absolute and relative body, heart, liver and testes weights compared to the control group whereas plasma testosterone concentration was similar among the different groups.

5. It was concluded that in ovo injection of RJ may be an effective method to increase the body weight of hatched chicks as an absolute value (CWT) and chicks' internal organ weights.  相似文献   

2. Mean GH concentration, baseline and amplitude of pulses were slightly, but not significantly, greater in LF chickens. Length and frequency of pulses were similar.

3. LF chickens exhibited higher plasma triiodothyronine (T3) concentrations. This difference between genotypes disappeared when the diet was supplemented with 1 mg/kg T3.

4. Specific binding of GH to liver membranes was higher for the fat line but was depressed by T3 supplementation to the same level in both lines. No difference was observed between lines for affinity constants.

5. It is concluded that direct selection for leanness has a less pronounced, if any, effect on GH pulsatility as compared with selection for food conversion efficiency; therefore, different physiological mechanisms are triggered to achieve leanness.  相似文献   

2. GH and prolactin concentrations were highest in young birds and higher in males than in females.

3. In both sexes GH and prolactin concentrations were correlated inversely with age and body weight and positively with relative weight gain.

4. Differences in growth rate between broilers and layers were related to differences in blood GH concentrations.

5. Water deprivation for periods of 6, 12, 18 or 24 h increased plasma prolactin markedly but did not affect GH secretion significantly.  相似文献   

2. Differences in the 4 genotypes, additive direct and maternal crossbreeding effects and heterosis were estimated on the following traits: age at first egg, egg production to the ages of 30, 35, 40 and 52 weeks of age, egg weight at 30 weeks of age, and (egg) fertility by artificial insemination with Muscovy drakes’ pooled semen.

3. Egg production up to 52 weeks of age was higher in Ts than in Pk (respectively 214 ± 7 and 150 ± 8 eggs), but not statistically different from that of the reciprocal crossbreds. The ratio of settable eggs to total eggs was nearly 90%, without any difference between genotypes.

4. Average egg weight at the age of 30 weeks was 75 ± 0.9 g for Pk, which was higher than the corresponding values for Ts (62 ± 0.8 g), but not significantly different from the crossbreds.

5. An effect of genotype was found on egg fertility: the Pk strain exhibited the lowest value, 71.3 ±3.1% compared with 75.9 ±2.1% for Ts, 80.6 ± 2.6% for Ts × Pk and 74.6 ± 1.9% for Pk × Ts.

6. Crossbreeding genetic variables showed favourable direct genetic effects for egg production and (egg) fertility in Ts, while Pk had favourable direct genetic effects on egg weight. The Pk genotype had a favourable maternal effect on fertility. Direct heterosis was 34% and 10% for egg production up to 30 and 52 weeks of age respectively, 8.8% for egg weight and 5.4% for (egg) fertility.

7. Crossing Ts with Pk seems profitable for the production of mule ducklings.  相似文献   

2. T4 concentration increased in the order SS, RR, LL in both sexes and did not vary significantly between sexes; the SS line had a significantly higher value than that of the LL line.

3. The body temperatures of SS, RR and LL lines were 42.45, 42.03 and 41.25°C in males, and 42.7, 42.03 and 41.63°C in females.

4. The oxygen consumptions of SS, RR and LL lines were 63.4, 46.0 and 43–8 ml/kgW^0.75 min. in males, and 61.4, 44.8 and 37.2 in females. The value for SS was significantly higher than those of RR and LL lines in both sexes (P< 0.01). The carbon dioxide productions of SS, RR and LL lines were 31.8, 33.8 and 27–3 ml/kgW⁰⁷⁵ min. in males, and 31.2, 31.9 and 27.3 in females. In both sexes, that of the LL line was significantly lower than those of the SS and RR lines (P< 0–01).

6. The heat productions of SS, RR and LL lines were 1.178, 0.994 and 0.842 k]/kgW^01b min. in males, and 1.142, 0.879 and 0.736 in females. In both sexes, the heat production of the SS line was higher than those of the RR and LL lines (P< 0–01).

7. It was demonstrated that selection for body weight in Japanese quail was accompanied not only by changes in growth rate and conversion efficiency but also by changes in thyroid function and energy metabolism.  相似文献   

2. At T_a 32 °G there was no panting. At T_a 35 °G panting occurred without any increase in T_r but there was a slight alkalosis (pH 7.55).

3. At T_a 38 °G T_r increased and panting was accompanied by moderate alkalosis (pH 7.58).

4. At T_a 41 °G T_r increased considerably and severe alkalosis developed (pH 7.65).

5. From the relation between T_r , f and pH it is concluded that some degree of alkalosis is a normal response to panting in the laying hen.  相似文献   

2. Male and female day-old Ross 308 chicks were fed on a standard commercial diet containing 0, 2.5, 5 or 10 g/kg feed ground M. officinalis for 84 d before slaughter.

3. Weight gain and feed conversion ratio were significantly improved in the broilers receiving either 5 or 10 mg M. officinalis/kg feed.

4. Inclusion of M. officinalis did not affect muscle chemical and fatty acid composition.

5. On the basis of microbiological and sensory experimental data and subsequent extension of meat shelf life, M. officinalis did not reduce the microbial populations of the meat, but was effective in limiting lipid oxidation.  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. Total RNA was extracted from the breast muscle, and cDNA was amplified using real-time PCR with primers specific to the examined genes.

3. Quail fed the diet with 12% glycerol supplementation presented higher growth hormone (GH) mRNA expression than did those fed 0% glycerol. Supplementation with 12% glycerol negatively influenced IGF-I mRNA expression and reduced ANT mRNA expression in comparison with the treatment with no glycerol. COX III mRNA expression in the pectoralis superficialis muscle was decreased by 26% in quail fed 12% glycerol compared with those fed 0 and 4% glycerol.

4. There was no difference in UCP mRNA expression between quail fed 0 and 4% glycerol; however, UCP expression was reduced (73%) in birds fed the 12% glycerol diet compared with the level in those fed the 4% glycerol diet.

5. The inclusion of 4% glycerol in the diet produced results similar to those of the diet with no glycerol. Based on quail performance and the expression of the GH, IGF-I, ANT, COX III and UCP genes, 4% glycerol can be used in quail feeding without any harmful effects.  相似文献   

2. Twenty male broiler chickens were used. Animals were divided into two groups, each comprising 10 animals. An intravenous dose of 0.75 mg of deltamethrin/kg body weight was given intravenously to the first group and the same dose (0.75 mg/kg body weight) was administered by intracrop by gavage to the second group. Blood samples were also collected at specified intervals.

3. Serum deltamethrin levels were measured via micro-electron capture detection with gas chromatography equipment. According to the serum deltamethrin level-time curve, deltamethrin tended to distribute according to a two-compartment open model.

4. The half-life at β phase (t_1/2β), mean residence time (MRT) and area under the concentration time curve in 0-∞ (AUC_0→∞) values after intravenous application of deltamethrin were 4.00 ± 0.76 h, 4.65 ± 0.75 h and 702.27 ± 236.07 ng h/ml, respectively. Furthermore, the absorption half-life (t_1/2a), maximal concentration in serum after intracrop administration (C_max), time needed to reach C_max (t_max), t_1/2β, MRT and AUC_0→∞ values after intracrop application of deltamethrin were determined to be 0.18 ± 0.06 h, 19.65 ± 4.58 ng/ml, 0.70 ± 0.10 h, 7.27 ± 1.36 h, 10.46 ± 1.84 h and 153.33 ± 30.83 ng h/ml, respectively. The bioavailability of deltamethrin was 21.83%.

5. It was concluded that deltamethrin was rapidly but incompletely absorbed after intracrop administration and bioavailability was at a low level. The t_1/2β and MRT of the deltamethrin were short for both intracrop and intravenous applications, and the risk of toxic and residual effects of deltamethrin is therefore limited.  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. Significant correlations were found between DP and DME (0#lb50; P < 0#lb01), DP and DAF (0#lb61; P < 0#lb01), and DME and DAF (0#lb65; P < 0#lb01) contents.

3. Using multiple regression models, growth and food utilisation efficiency (FUE) were found to be dependent on the linear and quadratic effects of DME (r² values = 0#lb67 and 0–64 respectively). Growth and FUE were also dependent on the linear and quadratic effects of DP (r² values = 0#lb70 and 0#lb49 respectively).

4. By including the effects of DME, DP and DAF in the gain and FUE models it was shown that growth and FUE were dependent on DME, DP and DAF (r² values = 0#lb76 and 0#lb79 respectively).

5. It was concluded that hypotheses concerning the broiler's response to DME and DAF were both correct but incomplete. DME, DP and DAF contents must all be known to predict accurately growth and FUE.  相似文献   

2. A total of 320-d-old chicks (Ross 308, average BW 44.0 ± 3.4 g) were randomly allotted to 4 dietary treatments on the basis of initial body weight (BW). The dietary treatments were negative control (NC; basal diet), positive control (PC; basal diet + 15 mg avilamycin/kg diet) and AMP-A3 (basal diet supplemented with 60 or 90 mg/kg AMP-A3). The NC diet was considered as 0 mg/kg AMP-A3 treatment. Experimental diets were given in two phases: starter phase (d 0–21) and finisher phase (d 22–35).

3. The overall BW gain and retention of dry matter (DM), gross energy (GE; d 19–21) and crude protein (CP; d 19–21 and d 33–35) were greater in birds fed on the PC and 90 mg/kg AMP-A3 diets than in birds fed on the NC diet. Also, an increase in dietary AMP-A3 linearly improved BW gain and retention of DM, GE (d 19–21) and CP (d 19–21 and d 33–35).

4. Birds fed on the PC and 90 mg/kg AMP-A3 diets had fewer excreta coliforms (d 21 and d 35), total anaerobic bacteria (TAB) and Clostridium spp. (d 35) and ileum and caecum coliforms (d 35) than birds fed on the NC diet. In addition, birds fed on the diet supplemented with increasing levels of AMP-A3 had linearly reduced excreta TAB (d 35), Clostridium spp. and coliforms (d 21 and d 35) and ileum and caecum coliforms (d 35).

5. Birds fed on the PC and 90 mg/kg AMP-A3 diets had greater villus height of the duodenum, jejunum and ileum than birds fed on the NC diet. Moreover, birds fed on increasing levels of AMP-A3 diet had increased (linear) villus height of the duodenum, jejunum and ileum.

6. These results indicate that 90 mg/kg AMP-A3 has the potential to improve growth performance, nutrient retention and intestinal morphology and to reduce harmful microorganisms in broilers and can be used as a potential antimicrobial growth promoter.  相似文献   

2. Heritability estimates of performing FP were 0.05 ± 0.06, 0.14* ± 0.07 and 0.38** ± 0.12 for 6, 38 and 69 weeks respectively for sum of pecks (PECKS) and 0.13* ± 0.07, 0.13* ± 0.07 and 0.35** ±0.12 for sum of bouts (BOUTS).

3. Heritability estimates of receiving FP were not significantly different from 0 except at 6 weeks (0.15* ±0.07 and the average of the 3 age classes (AVG) (0.22** ± 0.09) for PECKS and at 6 weeks (0.15* ±0.07) using BOUTS.

4. Genetic correlations of performing FP among age classes were in general high and significant. This was not the case with receiving FP.

5. Plumage cover at 51 weeks had a negative genetic correlation with performing FP at 69 weeks and AVG, but not with receiving FP. No phenotypic correlations were significant between plumage and FP.

6. Body weight at 51 weeks had a negative genetic correlation with performing FP at AVG.

7. Heritability estimates for performing and receiving FP at 6 weeks correspond to those in the literature. No estimates have previously been reported on feather pecking at 38 weeks or 69 weeks.

8. Selection of birds with no or a very low tendency to perform feather pecking should, on the basis of our results, be feasible.  相似文献   

2. A control diet containing corn–soybean meal and test diets containing 50, 100, 150, 200 and 250 g/kg of three lupin species were fed to broiler chickens during a 35-day study period. There were 10 replicate cages of 8 broiler chickens per treatment.

3. Growth performance of the birds fed with yellow and white lupin diets was found to be similar to that of the birds in the control group. The use of narrow-leaved lupin seeds in the diet quadratically decreased the body weight gain of birds and increased feed conversion ratio during all the experimental periods (0–14, 15–35 and overall 0–35 days of age).

4. A significant interaction between lupin species and their inclusion levels for apparent metabolisable energy and apparent ileal digestibility of starch was observed, showing a negative effect of increasing levels of narrow-leaved lupin. Pearson correlation coefficients demonstrated that the presence of raffinose and non-starch polysaccharides is a key factor affecting the nutritive value of lupin,

5. Yellow and white lupins could be utilised as an alternative ingredient for soybean meal in the diet of broiler chickens without any adverse effects on growth performance. The narrow-leaved counterpart diet reduced broiler performance, and hence did not provide a satisfactory outcome.  相似文献