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The experiment was carried out with 60 TETRA BLANCA laying hens chosen from 250 TETRA BLANCA pullets based on their body fat content, predicted at 16 weeks of age by means of computer tomography (CT). Pullets with the highest (n=20), lowest (n=20) and average (n=20) body fat content were chosen for the investigation. Changes in the body fat content of the experimental animals were followed by means of computer tomography in vivo, scanning the hens at every fourth week of the experiment, between 20 and 72 weeks of age. Eggs produced by these birds, were collected at 32, 52 and 72 weeks of age and, after breaking them, their yolk, albumen and egg shell ratio was determined and their dry matter, crude protein and crude fat content was chemically analyzed. Based on the results it was established that the body fat content of the hens started the egg production with high body fat content being higher than that of the hens started the egg production with average or low body fat content during the whole experimental period. The differences in the body fat content of the two extreme groups were statistically proven between 24 and 48 weeks of age (P0.05) by the starting body fat content of the hens.

Non-invasive computerized tomography was performed on commercial broiler chickens, in both sexes, between 4 to 18 weeks of age, with the aim of body composition measurement. On the basis of 16–32 scans gathered from each bird during the scanning procedure, volumetric measurement of the breast muscle was performed. These values were at the 259; 493; 786 cm3 and 195; 460; 668 cm3 in male and female birds at the age of 6, 12 and 18 weeks, respectively. The total body fat content was characterized by the so called „fat index”, a value independent of the live weight. This indices were 7,3; 7,14; 9,48 and 8,8; 13,3; 21,6 following the above order. Total body fat and crude protein was determined both by CT and chemical analysis. The variables of the prediction equations were taken from the density values of the Hounsfield scale between −140 and +150, by summarizing the frequencies within each interval of 10 values. Several models were developed with Principal Component Analysis. The R² values of the estimations were high (R2 = 0,89; 0,88) for total body fat but moderate (R2 = 0,39; 0,44) in the prediction of crude protein content. The investigation of the tissue development in the body was carried out by means of 3D histograms.

1. The aim of this study was to compare the changes in the production and in the body and egg composition of 45 TETRA SL brown egg layers and 45 TETRA BLANCA white egg layers during the first egg-laying period. 2. Changes in the body composition of the hens were followed in vivo by means of computed tomography (CT) four-weekly, between 20 and 72 weeks of age. The measurements covered the whole body of the hens using overlapping 10 mm slice thicknesses on a Siemens Somatom Emotion 6 multislice CT scanner. 3. The yolk, albumen and shell ratio of the eggs, produced on the days of the CT measurements by the hens, were determined and their composition was analysed chemically. 4. The body fat content of the hens increased continuously until 44 weeks of age and plateaued thereafter in both genotypes. However, the body fat content of the white egg layers was always higher than that of the brown egg layers. 5. The yolk ratio and the dry matter and crude fat content of the eggs of white egg layers were higher than the brown egg layers throughout the experiment. 6. Moderate correlations were observed in both genotypes between the body fat content of the hens and egg yolk ratio of their eggs.

A total 120 laying hens (60 TETRA BLANCA white egg layers and 60 TETRA SL brown egg layers) were selected from 250 TETRA BLANCA and 250 TETRA SL pullets based on their predicted body fat content by means of computed tomography (CT) at 16 weeks of age. Three groups of pullets were chosen for the investigation with the highest (n = 20), lowest (n = 20) and average (n = 20) body fat content. Changes in the live weight, body fat content, egg production and egg composition of the chosen animals were recorded at 32, 52 and 72 weeks of age. Based on the results, it was established that differences in starting body fat content of the hens remained the same during the experimental period. The differences between the two extreme groups were statistically significant at each age. The starting body fat content of the hens affected the rate of egg production, i.e. hens with high starting body fat content produced 11-14 eggs fewer than the hens with a low or average body fat content but had no effect on the composition of the eggs. Genotype affected almost all of the examined traits: TETRA BLANCA hens had lower live weight and higher body fat content during the experimental period and produced fewer eggs with lower albumen and higher yolk, dry matter and crude fat content than the TETRA SL hens.

Title of the paper: Effect of selection on body fat content by means of the TOBEC method on some reproductive traits of rabbit does and on the body composition of growing rabbits In this experiment body fat content of Pannon White growing rabbits was determined at 10 weeks of age using an EM-SCAN SA-3152 type Small Animal Body Composition Analyser (TOBEC method). Based on the fat content determined the best and worst 16% of the does and the best and worst 8% of the bucks were chosen and mated with each other (fatty doe with fatty buck and lean doe with lean buck). It was found that the conception rate was significantly higher and the number of inseminations needed for the second kindling significantly lower in the case of fatty rabbits. An important, but not significant difference was observed in the case of total litter size at birth, which decreased in the case of live born litter size. This reason was the significantly higher ratio of the dead born pups in the case of non-fatty rabbits. Due to the higher ratio of total litter loss and suckling mortality in the case of fatty rabbits the litter size at 21 days differed notably, but again not significantly. In the offsprings of the F1 generation it was found that the fat content estimated and also the ratio of scapular and abdominal fat to the live weight calculated differed significantly (P < 0.05) from each other in the two experimental groups. The estimated fat content was 42% higher in the offsprings of fatty than in the offsprings of non-fatty rabbits. The differences in the ratio of the scapular and abdominal fat content to the live weight were 26% and 51%, respectively.

[EN] An experiment using Magnetic Resonance lmaging (MRI) tomography were done inwlving 87 rabbits el four genotypes, 12 or 16 weeks old. MRI was applied on the day before slaughter. The slices were taken in three orthogonal planes. The resufting pictures indicate that MRI provides very detailed slices. The volume of the fat deposit around the kldneys, the tml body fat volume of the body and the muscle el the hind part was collected from the MRI pictures. Correlation coefficients were computad between the volume of the perirenal fat ancl its weight, the muscle volume el the hind part ancl its weight, the tctal body fat volume and the crude fat content. The correlation values were found to be very high (O. n to 0.94) in the group of age 16 proving that the MRI tomograph is a excellent In vivo method to determine the volumes of fat and muscle. The la.ver correlation values in the group el age 12 (0.39 to 0.76) indicate that the MRI tomography is sensitiva to the digital sampling errors., [FR] Un total de 87 laplns appartensnt lt 4 génotypes ~s de 12 lt 16 semalnes ont été étudlés par lmsgerie en résonance magnétique (IRM). Les laplns ont été ana/ysés par IRM Is vei//e de fsbattage. Les "coupes• ont été réalisées dans 3 p/Bns orthogonaux. Les images obtenues pour chaque coupe sont tres détaillées. Le volume de la masse adipeuse p(riénBle, de fensemble des masses adipeuses du COITJS et ce/ui des masses musculaires de farrilJre de fanimal ont été détermlnées par analyse de coupes. Les coefficients de corrélation entre ces volumes détermlnés par IRM et /eur poids mesuré par dissection aprés abattage sont de O, 77 lt 0,94 chez les laplns de 16 semalnes. Ceci atieste que f/RM est une bonne méthode pour la mesure in vivo des volumes de tissu adipeux ou musculaire. Les vBleurs beaucoup plus faibles des corrélations obtenues chez les laplns de 12 semalnes, (0,39 it O, 76) montrent la limite de f/RM pour ce type d'étude (faible masse des tissus adipeux) en raison de se sensibilité aux erreurs d'analyse des images infonnatiques numérlsées, This work was supported by the E.C. (Copernicus) as a part of project CIPA-CT93-0206. The authors gratefully ackowledge E. Biro-Németh, L. Radnai and the staff of the CT Biological Centre of the Pannon Agricultural University for their expert assistance

[EN] For 267 Pannon White growing rabbits of both sexes slaughtered at a body weight of 2.2-2.4, 2.4-2.6, 2.6-2.8, 2.8-3.0, 3.0- 3.2, 3.2-3.4 and 3.4-3.5 kg, the average dressing percentage was 59.5, 60.7, 61.9, 62.2, 61.4, 62.4 and 62.1 % respectively. While the weight of live animals increased by about 50 % between 2.29 and 3.42 kg the change in the weight of blood (23 %), full gastrointestinal tract (26 %) and head (35 %) were the lowest, whereas the intermediate part (65 %), liver (82 %), skin (73 %), meat on hind legs (74 %), meat on the intermediate part (85 %) and perirenal fat (326 %) gained weight the most rapidly. 129 Pannon White rabbits were slaughtered between 2.2 and 3.5 kg live weight. The water, protein, fat and ash content of their meat was analyzed in the M. longissimus dorsi (LD), hind leg (HL) and M. /ongíssimus dorsi + belly (LD + B). Water content averaged 74.8, 73.8 and 71.0 % in LO, HL and LD + B respectively, whereas protein, fat and ash content averaged 23.1, 22.1 and 21.7 %, 1.08, 3.24 and 6.39 %, 1.15, 1.09 and 1.04 % respectively, in the arder of the meat parts Usted above. Water content decreased and fat content increased with increasing weight (r = -0.47, -0.33 and -0.51, r = 0.38, 0.31 and 0.45 for water and fat contents of LD, HL and LD + B respectively). Protein and ash content did not change significantly with weight., [FR] Pour 267 /apins en croissance de génotype Pannon White, des deux sexes, abattus au poids vif de 2,2-2,4; 2,4-2,6; 2,6-2,8; 2,8-3,0; 3,0- 3,2 ; 3,2-3,4 ; 3,4-3,5 kg, le rendement moyen a /'abattage a été de 59,5 - 60, 7 - 61,9 - 62,2 - 61,4 - 62,4 et 62, 1% respectivement. A/ors que le poids vif des animaux augmente d'environ 50% entre 2,29 et 3,42 kg, les augmentations de poids du sang (23%), du tractus gastrointestinal plein (26%), et de la téte (35%) ont été inférieures a cene du poids vif. A /'inverse, les augmentations de poids du rSble (65%), du foie (72%), de la peau (73%), des muse/es des pattes arriares ou du rSble (7 4% et 85%) et surtout du gras périrénal (326%) ont été plus rapides que ce/le du poids vif. Par ailleurs, 129 lapins Pannon White ont été abattus entre 2,2 et 3,5 kg de poids vif. Les teneurs en eau, protéines, lipides et matiares minéra/es ont été déterminées pour le muse/e longissimus dorsi (LO), /es muse/es d'une patte arriare (HL) et /'ensemble muscu/aire longissimus dorsi + paroi abdominale (LO + B). La teneur moyenne en eau est de 74,8- 73,8 et 71,0% pour LO, HL et LO+ B, tandis que les teneurs moyennes en protéines, lipides et minéraux des mémes ensemb/es muscu/aires sont de 23, 1 - 22, 1 et 21, 7 % ; 1,08 - 3,24 et 6,39% ; 1, 15 - 1,09 et 1,04 respectivement. Quand le poids vif augmente, la teneur en eau diminue et la teneur en lipides augmente (r = -0,47, -0,33 et -0,51 ; r = +0,38 ; +0,31 et +0,45 pour /'eau et les lipides de LO, HL et LO + B, respectivement). Les teneurs en protéines et en matiares minérales ne varient pes significativement avec le poíds vif.

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.

The effect of egg size and composition on the viability of the offspring has been tested in several former experiments, but the clarification of these correlations was mainly hindered by the lack of a reliable technique/equipment, capable of determining the egg composition in vivo. In the course of the present work electrical conductivity (the so-called TOBEC method) was applied for determining the fat-free mass and the fat content of intact eggs in vivo. Using hen’s eggs in this trial it was established that for predicting the fat-free mass in hen’s eggs, the weight of eggs seems to be a very good predictor (R2=0.99) and therefore the use of the TOBEC method is not necessary in this case. In prediction of the weight and ratio of fat, the common use of the E-value (total conductivity index) and weight of eggs in the regression models resulted in a medium accuracy of prediction (R2=0.48-0.49).