Search

1. Using the so-called TOBEC (Total Body Electrical Conductivity) method, which allows the determination of egg composition in vivo, correlations between egg composition, hatchability and hatched chicks' development were studied. 2. A total of 1500 hen eggs (Ross-308) were measured by TOBEC, and eggs with extremely high (10%, n = 150), extremely low (10%, n = 150) and average (10%, n = 150) electrical conductivity values were chosen for further investigation. 3. During the incubation period, it was observed that eggs with high electrical conductivity had a significantly higher mortality than eggs with low electrical conductivity. 4. It was observed that both the increase in electrical conductivity at the same egg weight, and the increase in egg weight at the same electrical conductivity resulted in an increase in the hatching weight. 5. It was found that the dry matter, protein and fat content of the chicks hatched from eggs with low electrical conductivity was higher at hatching than that of the chicks hatched from eggs with high electrical conductivity. 6. At 42 d of age the liveweight of cocks and pullets hatched from eggs with low electrical conductivity was 3.2 and 8.2% higher than the liveweight of cocks and pullets hatched from eggs with high electrical conductivity. 7. Because of the higher liveweight at slaughter, there was a significant superiority of the chicks hatched from eggs with low electrical conductivity in the case of the examined carcase traits at slaughter. 8. Similar tendencies were found also in the ratios of carcase variables to liveweight, but the between group differences were not statistically significant in this case. 9. Based on the results it was concluded that TOBEC seems to be a useful method for separating eggs with different composition. 10. This could be a good starting point for further in vivo investigations in order to clarify the effect of egg composition on hatchability and further development.

A follow-up study was performed to describe characteristic physiological alterations by means of computer tomography, direct chemical analysis and histology of the liver, and blood biochemical parameters during conventional force-feeding of Landes geese. 30 birds were exposed to an 18-day long force-feeding. Sampling was performed at the start and during force-feeding (7th, 11th, 14th, 18th days). Computer tomographic data were plotted in 3D histograms, effectively indicating the volumetric development and the fat deposition of the liver. Applying the so-called fat index, a saturation process was found for the hepatic fat content. Histological sections indicated the appearance of microvesicular fat forms in the hepatocyte cytoplasm, which first turned to a total fatty infiltration, later changing to a macrovesicular form with progressing inflammation; membrane damage was not visualized. In blood metabolites triglyceride, total and HDL cholesterol and uric acid increased measurably, while creatinine concentration decreased. Alanine aminotransferase, aspartate aminotransferase activities increased strongly, while that of lactate dehydrogenase only slightly. Based on the results of macroscopic and microscopic imaging techniques and blood biochemical parameters, a comprehensive follow-up study was performed, elucidating still unknown processes during force-feeding of geese.