The influence of line and laying period on the relationship between different eggshell and membrane strength parameters.

We investigated the correlations between different eggshell and membrane strength parameters and their changes over time. Eggshell and membrane characteristics were measured for 2 different lines of laying hens, Hisex Brown and Bovans Brown, from wk 33 up to wk 78. Several parameters were investigated: 2 parameters concerning total eggshell strength (static and dynamic stiffness), 1 structural parameter (i.e., eggshell thickness), 2 parameters describing the material characteristics of the shell [dynamic Young's modulus (EM) and nitrogen content], and 3 parameters to measure the membrane characteristics (attachment force breaking strength and nitrogen content). This study shows that the correlations among parameters change during the laying period and among lines. The EM of the eggshell increased during the laying period for the Hisex line. No difference was observed in case of the Bovans line. In general, a negative correlation was obtained between eggshell thickness and the EM. The correlation between static and dynamic stiffness increased during lay. Finally, the attachment force and breaking strength of the membranes declined during the laying period.

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.

Measuring the eggshell strength of 6 different genetic strains of laying hens: techniques and comparisons.

1. Eggshell quality was compared in 6 different strains of laying hens. Three strains were commercial; the three others were experimental. 2. Four different variables describing the strength of eggshells were investigated. Three of them were the classical ones eggshell thickness, shell stiffness measured during quasi-static compression and breaking force. Dynamic stiffness, introduced by Coucke (Ph.D. Thesis, KU Leuven, 1998), was the 4th. The fact that this measurement is dynamic could be helpful in genetic selection for eggshell breakage, because forces applied to the egg in practice are dynamic, rather than static. 3. Hisex White hens produce eggs with the strongest eggshell, in terms of all 4 eggshell variables. However, their shell quality in terms of breaking force did not remain constant over the laying period, unlike 4 other strains. 4. All strains showed a decline in quasi-static stiffness over time. 5. The eggshell thickness of three strains showed a decline over time. 6. Dynamic stiffness remained constant or improved in all strain. 7. All variables describing the mechanical eggshell strength gave different information.

Early and temporary quantitative food restriction of broiler chickens. 2. Effects on allometric growth and growth hormone secretion.

1. An experiment was conducted with male broiler chickens to investigate the effect of different early food restriction programmes on proportional weights and allometric growth coefficients of carcase parts and on pulsatile growth hormone secretion. 2. At 4 d of age the animals were restricted to 80% or 90% of the ad libitum intake for 4 d or 80% for 8 d. When the restriction was finished, all birds received ad libitum food again. 3. On d 1, 8, 11, 14, 21, 28, 35 and 42, from each group 8 birds were weighed, stunned and killed and the weights of the stomachs, liver, heart, sternum, right thigh, right drumstick, breast and abdominal fat pad were determined. On d 29, 30, 31, 32 serial blood samples of 2 birds from each group were taken to determine the plasma growth hormone (GH) content. 4. Only the most severe restriction resulted in a tendency for the stomachs to mature earlier and the thighs to mature later. No other significant effect on the allometric coefficients could be observed. 5. It is concluded that during the restriction the birds give priority to the development of the supply organs such as the stomach, which are more important during early development at the expense of the demand tissues like breast and thigh. 6. No significant differences concerning the GH secretory parameters could be observed.

Renal transplantation in end-stage sickle cell nephropathy.

BACKGROUND: The role of renal transplantation as treatment for end-stage sickle cell nephropathy (SCN) has not been well established. METHODS: We performed a comparative investigation of patient and allograft outcomes among age-matched African-American kidney transplant recipients with ESRD as a result of SCN (n=82) and all other causes (Other-ESRD, n=22,565). RESULTS: The incidence of delayed graft function and predischarge acute rejection in SCN group (24% and 26%) was similar to that observed in the Other-ESRD group (29% and 27%). The mean discharge serum creatinine (SCr) was 2.7 (+/-2.5) mg/dl in the SCN recipients compared to 3.0 (+/-2.5) mg/dl in the Other-ESRD recipients (P=0.42). There was no difference in the 1-year cadaveric graft survival (SCN: 78% vs. Other-ESRD: 77%), and the multivariable adjusted 1-year risk of graft loss indicated no significant effect of SCN (relative risk [RR]=1.39, P=0.149). However, the 3-year cadaveric graft survival tended to be lower in the SCN group (48% vs. 60%, P=0.055) and their adjusted 3-year risk of graft loss was significantly greater (RR= 1.60, P=0.003). There was a trend toward improved survival in the SCN transplant recipients compared to their dialysis-treated, wait-listed counterparts (RR=0.14, P=0.056). In comparison to the Other-ESRD (RR=1.00), the adjusted mortality risk in the SCN group was higher both at 1 year (RR=2.95, P=0.001) and at 3 years (RR=2.82, P=0.0001) after renal transplantation. CONCLUSIONS: The short-term renal allograft result in recipients with end-stage SCN was similar to that obtained in other causes of ESRD, but the long-term outcome was comparatively diminished. There was a trend toward better patient survival with renal transplantation relative to dialysis in end-stage SCN.