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.

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.

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.

Effect of alternative rearing methods on the behaviour and on the growth and slaughter traits of growing rabbits

Abstract. The aim of this study was to compare the behaviour and the production and slaughter traits of growing rabbits reared in different alternative rearing systems and in conventional fattening cages. The experiment was carried out with 312 Pannon White growing rabbits between 5 and 11 weeks of age. According to the pen size, floor type and stocking density 8 experimental groups were created. For analyzing the different behavioural patterns 24 h video recordings were performed weekly by using infrared cameras. The body weight and the feed consumption of the rabbits were also measured weekly. At 11 weeks of age all of the animals were slaughtered and dissected. For the comparison of the behaviour and production of the experimental and control animals the Dunnett-test was used. It was established that the different alternative rearing methods have a significant effect only on the social and stereotype behaviour of the rabbits. The daily weight gain was highest in the control animals, while lowest in the rabbits reared on deep litter. The feed consumption, the feed conversion ratio and the slaughter characteristics were not affected by the rearing method. It was concluded that from the ethological point of view housing rabbits in pens – particularly on deep litter – has a favourable effect on both of the social and stereotype behaviours’ frequency. However, when rabbits are reared on deep litter, some consumption of the litter material should be calculated, but it does not decrease the pellet consumption and the final liveweight of the animals significantly.

Clinicochemical follow-up of broiler rearing--a five-week study

Commercial broilers were raised in a 5-week period and a detailed clinicochemical follow-up was carried out, to characterise a flock selected for one-sided muscle mass production. Blood samples were drawn at the ages of 1 day, 1, 2, 3, 4 and 5 weeks, and plasma enzyme activities, metabolite and ion concentrations were determined. Early increases were found for all plasma nitrogenous compounds (total protein, albumin, creatinine and urate). Triglyceride showed a posthatch peak with a significant effect of age. Plasma total cholesterol was characterised by a marked post-hatch concentration peak, while during the first week its concentration decreased markedly. Plasma AST showed an increase during the rearing, while a one-magnitude increment was found for creatine kinase activity during the study. The main results of the study outlined a typical precocial bird (post-hatch triglyceride peak; decreasing cholesterol and early peaking plasma protein and urate concentrations) with very quick skeletal muscle mass growth (increasing creatine kinase and AST activities, slight hyperkalaemia).

In vivo measurement of total body lipid content of common carp (<i>Cyprinus carpio</i> L.) by electrical conductivity

Abstract. non-destructive method to predict the total lipid content and the lean body mass (LBM) was evaluated by measuring the total body electrical conductivity (TOBEC) with common carp. This technique is based on the principle that body fat and fat-free mass differ in electric properties which can be measured in a low-frequency electromagnetic field. Experimental fish with average body weight of 1225 ± 298 g originated from a commercial stock. Fish were slaughtered immediately after the measurements and homogenized samples were taken from the grinded whole-body. The fat content of the homogenates was analysed using Soxhlet extraction after hydrochloric acid digestion. The weight of lean body mass (LBM) was calculated as the difference between the live weight and the weight of fat determined. The TOBEC method provided very precise estimation of lean body mass (R2 = 0.99). Total body lipid content (in gram) can also be predicted from the E value and live weight with adequate accuracy (R2 = 0.66) in the size range of 706–1989 g in common carp. The predictibility of the crude fat content (in %) was moderate (R2 = 0.37) in the present investigation. It could not be increased significantly by including other body measurements as standard lenght, height and circumference. Fat content of table-sized, sexually matured common carp can be estimated at a precision level that may be adequate only if high selection pressure has to be applied in a breeding program.

Non-invasive body composition measurement of broiler chickens between 4–18 weeks of age by computer tomography

Abstract. 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.

Einfluss des nach der TOBEC-Methode bestimmten Fettgehaltes bei Kaninchen auf die Wurfleistungen und die Körperzusammensetzung der Nachkommen

Abstract. 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.