Effect of starting body fat content and genotype of laying hens on the changes in their live weight, body fat content, egg production and egg composition during the first egg-laying period.

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.

Effects of different rearing systems on muscle and meat quality traits of slow- and medium-growing male chickens.

1. This experiment was conducted to evaluate the effect of production system on the meat quality of slow- and medium-growing chickens. A total of 1075 1-d-old male chicks were equally divided into 6 experimental groups, represented by three strains (SG: TETRA-H, MG1: TETRA HB Color, MG2: Shaver Farm) and were reared in a poultry house in floor pens (12 males/m(2)). 2. On d 49, 150 healthy birds (50/genotype) were placed in a free-range family farm while the rest of the birds remained indoors. All birds were fed ad libitum and consumed the same diet. On d 70, 20 birds of each experimental group were slaughtered and muscle samples were taken from the left breast and thigh muscles. 3. Thigh muscle of SG males kept on free range was darker (L* = 75.12 vs. 78.33) with lower frying loss (45.9% vs. 55.9%) compared with the indoor group. Similar results were obtained from the MG1 group. Free-range MG2 males had lighter thigh meat (L* = 50.7 vs. 57.8) and lower frying loss compared to the indoor group. 4. In general, the indoor treatment had a lower impact on breast meat than the outdoor system. Regardless of the rearing system, genotypic differences were more pronounced in thigh than in breast muscle.

Comparison of changes in production and egg composition in relation to in vivo estimates of body weight and composition of brown and white egg layers during the first egg-laying period.

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.

Application of computed tomography to assess the effect of egg yolk ratio on body composition in chickens of different genotype and gender at hatch and during the rearing period.

1. Computed tomography was used for the in vivo determination of yolk ratio in 7000 domestic hen eggs, originated from two markedly different genotypes, in order to examine the effect of egg yolk ratio, gender and genotype on the development of hatched chicks. 2. Eggs with extremely low, average and extremely high yolk ratio were chosen for further investigation (n = 350 in each group in both genotypes). After incubating the selected eggs, hatched birds were reared and slaughtered at 11 weeks of age. 3. The yolk ratio of eggs significantly affected the body composition of the chickens at hatching and during rearing to 8-9 weeks of age. 4. Chickens of a genotype selected partly for weight gain had significantly higher live weight from hatching to the end of the rearing period and had better slaughter characteristics than those of the dual purpose TETRA-H genotype. 5. At hatching, only the dry matter content of the body was affected by the gender of the birds. The effect of gender on the live weight and body composition of chickens was evident from the 5th week of age to the time of slaughter. 6. It was concluded that eggs with a low yolk ratio were most beneficial for broiler production, because chickens hatched from these eggs had the highest slaughter weight and muscle index and the lowest fat index for their body mass.

Computed tomographical (CT) anatomy of the thoracoabdominal cavity of the male turkey (Meleagris gallopavo).

In the present work, our goal was to match high-resolution computed tomography (CT) scans with cross-sectional anatomical pictures of the turkey (Meleagris gallopavo). Two male BUT 6 (a commercial line) turkeys were used. CT scans with 1 mm slice thickness were performed. The images covered the trunk from the level of the 9th cervical vertebra to the end of the coccyx. The anatomical sections and the CT scans were matched, and the important structures were identified and labelled on the corresponding pictures. The aim of this study was to create a reference for evaluating CT scans of avian species.

Effect of egg composition on hatchability and on growth and slaughter characteristics of meat-type chicks.

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.

Developmental dynamics of some blood biochemical parameters in the growing turkey (Meleagris gallopavo).

Blood serum clinical biochemical parameters of fasted BUT Big 8 male turkeys were determined at the ages of 3 days, 4, 8, 12, 16 and 20 weeks, for a follow-up of the developmental changes of some serum metabolites, enzymes and ions. The serum protein content (total protein, albumin, globulin) increased with age, indicating also the moulting-associated metabolic changes in the age interval from the 8th to the 12th weeks. Creatinine was shown to have a peak at 3 days of age (role of muscle activity in thermogenesis), while urate concentration sensitively reflected the dietary protein amount. Serum triglycerides peaked at the time of yolk catabolism, while cholesterol was shown to indicate the moulting, as was serum malondialdehyde. Serum sodium content increased throughout the study. Alanine aminotransferase and aspartate aminotransferase activities increased along the ontogeny, while alkaline phosphatase activity decreased in parallel with the growth. Serum creatine kinase activity showed an over one-magnitude increase. General metabolic and enzymatic alterations were characteristic and applicable for the description of the ontogenetic development of a precocial (post-hatch triglyceride peak), large bodied, meat-type (lactate dehydrogenase, continuously increasing creatine kinase) bird species.

Noninvasive characterization of the turkey heart performance and its relationship to skeletal muscle volume.

The cardiovascular capacity of turkeys is considerably affected by the selection procedure for meat production. To determine the body weight-related changes of some quantitative characteristics of the turkey heart function, serial measurements were carried out. BUT Big 6 turkeys (both sexes) were examined using whole-body magnetic resonance imaging (MRI) and spiral computer tomography (CT). Based on dynamic MRI examinations the following significant age- and sex-dependent quantitative differences were found. Means of the left ventricular stroke volumes were measured at the ages of 12 wk (males, 4.18 mL; females 2.89 mL), 16 wk (males, 6.56 mL; females, 4.14 mL), and 20 wk (males, 8.17 mL; females, 5.16 mL). Average cardiac output (CO) values were 0.76, 1.14, and 1.33 L/min for males and 0.58, 0.79,0.93 L/min for females. A statistically unproven age-dependent increasing tendency in the estimated relative CO value (skeletal muscle tissue volume measured by CT/CO unit) of male and female turkeys was found under sedentary conditions. These changes in the relative CO value and also the determined decrease of CO value related to body surface may, in theory, indicate a disadvantageous process that is more pronounced in males. The combined application of CT and MRI can be a powerful approach for studying the relationship between skeletal muscle development and heart capacity.