Gene expression profile of IGF1 and MSTN mRNA and their correlation with carcass traits in different breeds of geese at 70 d of age

1. The expression of insulin-like growth factor-1 (IGF1) and myostatin (MSTN) mRNA in breast and leg muscle was quantified in 70-d-old Taihu and Wanxi geese by using a Multiplex Competitive Fluorescent–PCR method and the correlations between mRNA levels and carcass traits were analysed.

2. IGF1 mRNA expression in breast muscle in Taihu geese was significantly higher than that in Wanxi geese and the MSTN mRNA level in leg muscle in Taihu geese was significantly higher than that in Wanxi geese.

3. There was no significant difference in breast muscle MSTN or leg muscle IGF1 mRNA expression between the two breeds.

4. Within the same breed, the IGF1 mRNA expression in leg muscle of male geese was significantly higher than that in female geese, and MSTN mRNA expression in leg muscle was significantly higher than that in breast muscle.

5. There was no difference in the IGF1 mRNA expression between tissues.

6. There was a positive correlation between IGF1 mRNA and MSTN mRNA and a negative correlation between IGF1 mRNA expression of breast muscle and leg muscle ratio.

7. In Wanxi geese, MSTN mRNA expression in leg muscle was negatively associated with body weight and leg muscle weight.     

Acceleration of post‐mortem changes in Tsaiya duck (Anas platyrhynchos) breast muscle by lactic acid marination

1. The effect of lactic acid marination at 5°C on post mortem changes in breast muscle pectoralis major of spent layer Tsaiya duck was studied.

2. Myofibrils were prepared from 0.1 M and 0.2 M lactic acid marinated muscle and control (non‐marinated samples) sampled at 0, 1, 3, 7 and 14 d post mortem.

3. Changes in myofibril fragmentation index (MFI), myofibrillar proteins and Z‐line structure were examined.

4. Marination of duck breast muscle in lactic acid at 5°C enhanced fragmentation of myofibrils and degradation of myofibrillar proteins and Z‐line structure as compared to control samples.

5. In summary, lactic acid marination at 5°C can accelerate the post mortem degradation of myofibrils in Tsaiya duck breast muscle.     

The occurrence of giant fibres in different muscles of two chicken genotypes

1. The occurrence of Giant Fibres (GF) in three muscles (Pectoralis major (PM), Iliotibialis lateralis and Semimembranosus) with different types of energy metabolism was studied in slow- and fast-growing chicken strains.

2. A total of 20 one-day-old Leghorn chicks (slow-growing) and 20 broiler (Ross 508) chicks (fast-growing) were reared to 100 and 45 d, respectively.

3. A small percentage of GF was seen in pre rigor muscle samples even at 3 min post mortem in both genotypes and in all muscle types studied.

4. From 3 min to 24 h post mortem GF increased both in Leghorn and broiler chickens but to a different extent according to muscle type and genotype.

5. The highest GF 24 h post mortem value was found in the PM muscles belonging to the fast-growing broiler line.

6. It was concluded that every type of muscle can develop GF, but this phenomenon is more evident in the PM especially in animals selected for increased growth rate.     

The influence of factory processing on the development of rigor in the breast muscle of broilers

1. The time course of rigor in broiler chicken breast muscle during factory processing was studied.

2. The texture of the breast muscle was compared with some of the major biochemical constituents at different stages of processing.

3. It was shown that rigor was still developing when the carcass was chilled. Subsequent blast freezing and thawing of chickens resulted in the muscle becoming considerably more tender.     

Possible use of an indicator muscle in future breeding experiments in domestic fowl

1. Domestic fowl were chosen for different body weights in descending order of size, viz. Tetra, Rhode Island Red/Light Sussex cross, White Leghorn and Bantam. The numbers and sizes of fibres in various muscles were determined by quantitative histology, and fibre number was also estimated by DNA measurement.

2. In contrast to the situation in mammals, fibre size (diameter) was of greater importance than fibre number in determining muscle size.

3. Biochemical measurement of DNA content in a muscle was not a reliable estimate of cell number without histological verification.

4. It is suggested that the anterior latissimus dorsi muscle could be used as an indicator muscle in future selective breeding programmes for fibre number because of its fibre arrangement and accessibility.     

Muscle structure and gene expression in pectoralis major muscle in response to deep pectoral myopathy induction in fast- and slow-growing commercial broilers

1. The objective of this study was to determine muscle structure and gene expression in pectoralis major (p. major) muscle of broilers in response to deep pectoral myopathy (DPM) induction.

2. A total of 160 chickens from slow- and fast-growing broilers were raised under same conditions. Half of the broilers from each strain were encouraged to wing flap when they reached 2800 g body weight. Pectoralis minor (p. minor) muscle of the broilers was inspected for the occurrence of DPM and p. major samples were collected from broilers with or without DPM. The muscle fibre area and number, capillary number and the signalling pathways of vascular development (vascular endothelial growth factor A, VEGFA) and muscle contraction regulation (actin alpha 1, ACTA1; myosin light chain kinase 2, MYLK2 and ATPase Ca⁺² transporting gene 1, ATP2A1) were studied in p. major muscle.

3. DPM induction increased fibre area of p. major muscle with a greater rate in the slow-growing strain compared with fast-growing line. Although the capillary number was higher in slow-growing compared with fast-growing broilers, in the case of DPM induction, the number of capillaries was similar between strains.

4. Expression of VEGFA, MYLK2 and ATP2A1 was greater in slow- than in fast-growing broilers. DPM induction increased expression of ACTA1, VEGFA and ATP2A1 in p. major muscle of broilers from both strains; however, MYLK2 expression was downregulated.

5. Changes in capillary density and expression of VEGFA found in the p. major muscle of broilers with DPM suggest increased blood flow to increase oxygen availability. The upregulation of ATP2A1 by DPM induction could be attributable to alterations in calcium ion transportation from the cytoplasm into the sarcoplasmic reticulum.

6. The results are evidence of changes in muscle structure and gene expression pathways in p. major muscle of broilers with DPM.     

Microbial status of chicken portions and portioning equipment

1. The sources and numbers of microbes contaminating poultry portions, which form an increasing proportion of poultry meat production were investigated. Total aerobic count at 30°C, pseudomonads, coliforms, enterococci and Staphylococcus aureus were enumerated.

2. Samples which had undergone different degrees of portioning, from whole birds to individual retail portions of poultry meat, were collected at points along the portioning line. Equipment surfaces, utensils and hands/gloves of factory personnel were examined.

3. In general, microbial numbers on carcase sampling sites were related to ‘exposure factor’, that is, the length of time the site was exposed to potential contamination during processing and portioning.

4. When results for individual sampling sites were analysed separately, no significant differences were found between sites on whole birds and the corresponding half bird sample sites. Comparison of numbers on half birds and on portions revealed a more variable situation.

5. Sites touched by rubber gloves when carcases were hung on the automatic portioning lines had greater contamination than other sites.

6. Provided factory and operative hygiene standards are high, portioning does not significantly increase numbers of microorganisms.     

Influence of heated vegetable oils and α‐tocopheryl acetate supplementation on α‐tocopherol,fatty acids and lipid peroxidation in chicken muscle

1. Chicks were fed on diets containing fresh, heated or α‐tocopheryl acetate‐supplemented heated vegetable oils. The effects on α‐tocopherol status, and on the fatty acid composition and oxidative stability of thigh and breast muscle were determined.

2. Plasma α‐tocopherol was significantly correlated with α‐tocopherol concentrations in thigh and breast muscle.

3. The fatty acid profiles of muscle lipids reflected dietary fatty acid composition.

4. The consumption of heated sunflower and linseed oils reduced α‐tocopherol status, altered fatty acid composition of muscle lipids and increased susceptibility of muscle to lipid oxidation.

5. Supplementation of diets containing heated oils with α‐tocopheryl acetate resulted in some alleviation of these effects.

6. The results indicate that caution should be exercised in the use of thermally oxidised oils in poultry diets if undesirable changes in composition and oxidative stability of carcase lipids are to be avoided.     

Neuromusgular studies of turkeys with trienbolone acetate‐induced and naturally occurring “leg weakness”

1. In vivo sciatic nerve gastrocnemius muscle preparations were made from 14‐ to 18‐week‐old normal turkeys and from those with naturally occurring or trienbolone acetate (TA)‐induced “leg weakness”.

2. Preparations from leg weakness cases displayed neither accelerated muscle fatigue nor decreased nerve conduction velocities as compared with control preparations.

3. The muscles of the TA‐treated turkeys but not of those with naturally occurring leg weakness were hyperexcitable relative to those of controls.

4. Post‐tetanic potentiation of preparations from both naturally occurring and experimentally‐induced cases of leg weakness was less than that of control preparations, both before and after partial neuromuscular blockade, significantly so at the lower pulse frequencies used.

5. It is tentatively suggested that the last finding might be of significance in explaining the clinical signs of leg weakness and might be associated with a disordered calcium metabolism.     

Different growth rates of male chicken skeletal muscles related to their histochemical properties

1. Early, M. pubo‐ischio‐femoralis pars medialis (PIF muscle) and late, M. iliotibialis lateralis pars postacetabularis (ITL muscle), maturing muscles were studied. These two muscles contained different populations of histo‐chemical fibre types.

2. The profile measurements of the muscles showed diphasic allometric growth relative to the weights. In the early stage of growth (up to 15 weeks after hatching), the muscle length, width and depth all increased, while in the later stage (from 15 to 35 weeks) muscle growth resulted mainly from the marked increase in the depth and to a lesser degree, from an increase in the width.

3. Type I fibres, observed predominantly in PIF muscle matured earlier than the Type II fibres of ITL muscle.

4. From these results, the detailed process of skeletal muscle growth in the chicken was discussed.     

The effect of heat stress on GHR,IGF-I,ANT, UCP and COXIII mRNA expression in the liver and muscle of high and low feed efficiency female quail

1. A study was conducted to test the hypothesis that feed efficiency (FE) correlated with the expression of genes from the somatotropic axis and mitochondrial genes involved in energy production, and that the environment to which the birds are exposed influenced the expression of such genes.

2. Quails were divided into High-FE and low-FE groups and maintained in a comfortable or heat stress (HS) (38°C for 24 h) environment to evaluate changes in insulin-like growth factor I (IGF-I), growth hormone receptor (GHR), adenine nucleotide translocator (ANT), uncoupling protein (UCP) and cytochrome oxidase subunit III (COX III) messenger ribonucleic acid (mRNA) expression in liver and muscle tissues.

3. High-FE quails (0.28 g/g) presented a higher final body weight, greater weight gain and a better feed conversion ratio than low-FE birds (0.18 g/g). High-FE birds showed greater IGF-I mRNA expression in the liver and muscle and greater GHR mRNA expression in the muscle.

4. Environmental effects only affected GHR expression in the liver, with quails under comfortable conditions exhibiting greater GHR expression than quails subjected to HS.

5. There was a significant interaction between FE and environmental temperature on ANT mRNA expression in the liver. The greatest ANT mRNA expression was observed for high FE-birds that remained under comfortable conditions.

6. In the liver, UCP mRNA expression did not differ among the quails and was not affected by environment or efficiency. However, comparisons of the low- and high-FE birds revealed higher levels of UCP mRNA in the muscle of low-FE birds.

7. COX III mRNA expression in the liver was dependent on environmental temperature and FE. Higher COX III mRNA expression was observed in animals that remained under comfortable conditions, and high-FE birds exhibited higher expression levels compared to low-FE birds.

8. These results suggest a correlation between IGF-I, GHR, ANT, UCP and COX III gene expression and FE and that environmental temperature could affect the expression of some of these genes.     

Effect of pyridoxine on the distribution of chloramphenicol and its residues in the chicken

1. Chickens were given either a single dose of chloramphenicol (50 mg/kg body weight per os) or a dose of chloramphenicol together with pyridoxine (25 mg/kg per os) given 1 h before or 4 h afterwards.

2. Concentrations of chloramphenicol were determined in samples of serum and the rates of distribution and elimination extrapolated. Concentrations of chloramphenicol in muscle, liver and kidney were also determined.

3. Serum concentrations of chloramphenicol were lower in chickens given both pyridoxine and chloramphenicol compared with those given only chloramphenicol.

4. Differences were most pronounced during the post‐absorptive phase. The rates of disappearance of chloramphenicol residues from tissues were enhanced by pyridoxine.

5. The biological half life of chloramphenicol and area under the concentration‐time curve were both reduced by the concurrent administration of pyridoxine.

6. Availability of pyridoxine may be a rate limiting factor in the biotransformation of xenobiotics, though its indiscriminate use could cause failure of antibiotic therapy.     

Effects of short intermittent lighting on food consumption and performance of dwarf broiler breeders and progeny

1. Two hundred and sixty four dwarf broiler breeder hens were subjected to ad libitum or restricted feeding and to four lighting patterns: 15L (bright light):9D (dark), 15L:9d (dim light), 2L:10d: 1L:11d, (0.5L:3.5d) × 6.

2. Breeder hens fed ad libitum and subjected to either conventional or intermittent lighting ingested respectively, 25 g and 14 to 17 g more than hens restricted to 115 g/d.

3. Body weight was greater in hens fed ad libitum irrespective of the lighting pattern and of the amount of food intake.

4. Persistency of egg production was impaired by intermittent lighting.

5. Ad libitum feeding reduced egg fertility. The decrease was larger in breeder hens on intermittent lighting.

6. Hatchability was increased in hens submitted to the symmetrical lighting pattern (0.5L:3.5d).

7. Egg and chick weights were higher in hens fed ad libitum.

8. Shell index and shell breaking strength increased in restricted hens on the intermittent lighting pattern (0.5L:3.5d) × 6.

9. The best performance was obtained in restricted hens on the conventional lighting pattern.     

Effect of Melissa officinalis supplementation on growth performance and meat quality characteristics in organically produced broilers

1. A trial was conducted to study the effect of Melissa officinalis supplementation on organic broiler performance and meat chemical, microbiological, sensory and nutritional quality.

2. Male and female day-old Ross 308 chicks were fed on a standard commercial diet containing 0, 2.5, 5 or 10 g/kg feed ground M. officinalis for 84 d before slaughter.

3. Weight gain and feed conversion ratio were significantly improved in the broilers receiving either 5 or 10 mg M. officinalis/kg feed.

4. Inclusion of M. officinalis did not affect muscle chemical and fatty acid composition.

5. On the basis of microbiological and sensory experimental data and subsequent extension of meat shelf life, M. officinalis did not reduce the microbial populations of the meat, but was effective in limiting lipid oxidation.     

Effect of early filleting on the texture of breast muscle of broilers stunned with argon‐induced anoxia

1. Eighty broilers were stunned in batches of 10 with less than 1 % oxygen (air displaced by argon) and their chilled breasts were filleted at 2, 3, 5 or 21 h (argon control) post‐mortem. Twenty broilers were electrically stunned and their breasts filleted at 21 h post‐mortem (electrical control).

2. Meat quality variables studied included pH of the pectoralis major muscle measured at 20 min post‐mortem and at filleting, and texture at 24 h post‐mortem.

3. Argon stunning resulted in a rapid early post‐mortem pH fall, but there was no indication of heat toughening in the breast muscles.

4. Filleting at 2 h post‐mortem, after argon stunning, resulted in 5% of the p. major muscles having greater than 4 kg yield force (slightly tough).

5. Although post‐mortem ageing of argon stunned broilers improved the texture of breast muscle, it is inferred that filleting at 2 h postmortem resulted in breast muscle with acceptable texture.     

Association of polymorphism in the prolactin promoter and egg quality traits in laying hens

1. Single strand conformation polymorphism analysis and DNA sequencing was performed in White Leghorn hens to explore the polymorphisms present in the promoter of the prolactin gene. The effects of different genotypes on egg production and quality traits were determined, and expression of the prolactin gene in different genotypes was quantified by real time-PCR.

2. Five genotypes and four alleles at each of two Fragments of the promoter were found, of which the FG genotype in Fragment 1 and the PQ genotype in Fragment 2 were the most predominant genotypes.

3. The genotypes of Fragment 1 had significant effects (P?

4. Prolactin expression in the genotypes of Fragment 1 differed significantly and GH genotyped birds had the highest level of expression. The genotypes of Fragment 2 did not show any significant differences of expression.

5. It was concluded that the prolactin gene promoter was highly polymorphic, and had significant effects on egg quality traits in White Leghorn hens.     

Behaviour of egg shell under compression in relation to deformation measurements1

1. The egg does not completely obey Hook's law when compressed between flat surfaces.

2. Deformation was not completely reversible due to crumbling at the points of contact with the force.

3. There are three components of non‐destructive deformation: (a) local deformation at the points of contact, (b) local surface crumbling and (c) deformation of the over‐all shell structure.

4. The latter two are uncontrolled, contributing to errors in the prediction of fracture force and depending on the non‐destructive force applied.

5. These effects should be considered in test selection and interpretation.

6. The optimum non‐destructive force was found to be 1 kg.     

Growth,food conversion,carcass yields and their heritabilities in ducks (anas platyrhynchos)

1. Live weight, food consumption, eviscerated carcass weight, breast muscle mass and ratios of these traits were measured in a strain of ducks of known pedigree. Heritabilities, genetic and phenotypic correlations were estimated for all traits. From the results the following conclusions are drawn.

2. Selection for live weight at market age would be simplest and most effective in improving growth rate and food conversion efficiency though would not necessarily markedly improve carcass lean meat.

3. Selection to increase the proportion of breast muscle (heritability (h ² ): 0.55) should be effective but might depress body weight as a correlated response. The effect on fat content is uncertain.

4. Selection for food conversion efficiency (h² : 0.21) might be expected to increase body weight, but its effect on carcass lean meat (proportion of breast muscle) is uncertain.

5. Selection for breast muscle mass (h ² : 0.41) should improve body weight and food conversion efficiency but its effect on proportion of lean meat is much less certain (rG = 0.45 + 0.17).