New approach of testing the effect of heat stress on eggshell quality: mechanical and material properties of eggshell and membrane

1. The effect of high temperature on eggshell quality was investigated by measuring the mechanical and material properties of shell and membranes. 2. Heat exposure resulted in a decrease in zootechnical performance and eggshell thickness, increase in egg breakage, and unchanged egg shape index. 3. The static stiffness (Kstat), dynamic stiffness (Kdyn) and modulus of elasticity of the eggshell were not significantly affected by high temperature. Membrane prolongation increased significantly while membrane attachment strength and breakage strength tended to decrease and increase, respectively. The relationships between these variables were changed by high temperature. 4. Neither Kstat nor Kdyn could give a reasonable explanation for the changed eggshell quality induced by heat stress. The decreased eggshell thickness and changed properties of shell membrane may be responsible, at least partially, for the decreased shell quality of eggs from heat-stressed hens.     

Physiological inhibition of growth hormone secretion by both insulin‐like growth factors‐I and ‐II in chickens

1. The role of both insulin‐like growth factors (IGF)‐I and ‐II in regulation of growth hormone (GH) secretion in chickens was examined. Seven‐week‐old male broiler chickens were injected intravenously (iv) with recombinant human IGF‐I or IGF‐II or specific anti‐IGF‐I or IGF‐II immunoglobulins. Blood samples were taken before treatment and at 15 min intervals afterwards for 1 h. Controls received saline iv.

2. Both IGF‐I and IGF‐II administration resulted in a rapid, significant decrease in plasma GH concentrations, but the concentrations of both triiodothyronine and thyroxine remained unchanged.

3. Immunisation against both IGF‐I and IGF‐II produced a significant elevation in plasma GH.

4. These data show that both IGFs can regulate GH concentrations in birds. Furthermore, the immunoneu‐tralisation data suggest that these hormones have a physiological role in the regulation of GH secretion.     

Increased sensitivity to triiodothyronine (T3) of broiler lines with a high susceptibility for ascites

1. In the studies reported here, broiler lines divergently selected for susceptibility to ascites under low temperature conditions were tested for their sensitivity to 3,3’,5‐triiodothyronine (T3) with respect to growth rate, rate of mortality, plasma concentrations of T3, right ventricular hypertrophy (RVH) and incidence of ascites.

2. Mean body weight of the ascites‐susceptible line (BC‐line) was higher than that of the ascites‐resistant line (A‐line). Adding 0.5 mg T₃/kg of the diet depressed growth rate to the same extent in both lines. The effect of T3 on growth was more pronounced for males than for females.

3. T3‐supplementation increased the relative weight of the heart and the incidence of RVH to the same extent in both lines. More of the T3‐treated BC‐line chickens had fluid accumulation in the abdominal cavity than the T3‐treated A‐line chickens.

4. Dietary T3‐treatment depressed the plasma concentration of growth hormone (GH) profoundly and insulin‐like growth factor (IGF‐I) slightly but to the same extent in both lines. The coefficient of variation of GH concentrations indicate that T3 treatment mainly decreased GH‐pulsatility in young growing broilers.

5. Higher doses of dietary T3 (1 and 2 mg/kg) increased mortality in a dose‐dependent manner. With 2 mg T₃/kg, mortality in the BC‐line was almost double that in the A‐line.

6. These studies indicate that the development of ascites could be linked with thyroid function. Moreover, dietary T3 supplementation could be used to help identify ascites‐inducing factors or genetic lines with differential sensitivity for ascites.     

Effects of high CO2 level during early incubation and late incubation in ovo dexamethasone injection on perinatal embryonic parameters and post-hatch growth of broilers

1. A total of 1200 Cobb broiler breeder eggs were incubated under either standard conditions (C group) or high CO(2) levels (CO(2) group) during the first 10 d of incubation. The CO(2) level of the CO(2) incubator was attained gradually by a natural build-up of CO(2) due to air-tight closure of the incubator. From d 10 of incubation onwards, all eggs were incubated under standard incubation conditions. At d 18 of incubation, the eggs of both incubation groups (CO(2) and C group) were either injected with water-soluble dexamethasone (DEXA group) or with saline (0.9% NaCl; saline group) or were not injected (control). 2. Body weights, plasma hormonal concentrations (T(3), T(4) and corticosteroid) and glucose concentrations were measured regularly during the perinatal (at IP, internal pipping) and post-hatch period (at 1, 2, 4 and 6 weeks post-hatch). Additionally, hatchability and pattern of embryonic mortality were determined after hatch. 3. The results showed that high CO(2) levels during the first 10 d of incubation or dexamethasone injection at d 18 of incubation decreased embryo mortality, mainly because of a reduction in embryo malpositioning. However, a combination of a CO(2) incubation and a dexamethasone injection led to an increase in embryo mortality and therefore a decrease in hatchability. 4. Although dexamethasone injection at embryonic d 18 decreased body weight in the second week of the rearing period and CO(2) incubation increased body weight during the first 2 weeks of the rearing period, no consistent effect of both the incubation and injection treatments on body weight at slaughter age was observed.     

Influence of whole wheat inclusion on optimal feed withdrawal duration

1. The objective of the present study was to examine whether the commonly applied duration of feed withdrawal (10 h) should be altered if broilers receive a commercial whole wheat (WW) diet instead of a completely pelleted (C) diet. 2. Inclusion of whole wheat in the diet did not affect weight gain, feed intake or feed conversion.3. The effect of different feed withdrawal (FW) durations on body weight loss was similar for both diets. 4. Gall bladder content was not significantly greater after longer feed withdrawal periods, irrespective of diet composition. Birds given the WW diet had significantly greater gall bladder contents than birds receiving the C diet. 5. Both diets had similar effects on wet weight of the total gut contents, mean relative wet contents of each gut region and percentage water content of the gut contents. 6. These results indicate that a feed withdrawal period of 10 h is sufficient for broilers on the WW diet.     

Polybrominated diphenyl ethers in seafood products of south China

South China is probably one of the heaviest polybrominated diphenyl ether (PBDE) polluted regions in the world, thanks to the presence of huge and rapidly growing electronics manufacturing industries, as well as several of the world's largest e-waste recycling sites in the region. In the present work, a wide variety of nonfish seafood products collected from South China was analyzed for PBDE residues. The concentrations of PBDEs in seafood products were highly species-specific, and the magnitude of PBDE pollution was moderate in South China compared to the global levels. Congener patterns of PBDEs in seafood samples suggested that seafood products are prone to accumulating low-brominated congeners, and possible metabolic debromination of BDE-99 to BDE-47 could occur in certain organisms, such as crabs and mantis shrimp. Generally, the congener profile was dominated by BDE-209, and to a lesser extent by BDE-47 and BDE-99, which was consistent with the fact that Deca-BDE is mass-produced in China and with previous sediment results from the same area. The occurrence of BDE-209 in aquatic species from South China suggests that BDE-209 appears to be more bioavailable than previously thought, and the environmental fate and safety of BDE-209 require further investigation and call for a thorough reassessment.