Muscle Growth and Poultry Meat Quality Issues

Over the past 50 years the worldwide growing demand of poultry meat has resulted in pressure on breeders, nutritionists and growers to increase the growth rate of birds, feed efficiency, size of breast muscle and reduction in abdominal fatness. Moreover, the shift toward further processed products has emphasized the necessity for higher standards in poultry meat to improve sensory characteristics and functional properties. It is believed that genetic progress has put more stress on the growing bird and it has resulted in histological and biochemical modifications of the muscle tissue by impairing some meat quality traits. The most current poultry meat quality concerns are associated with deep pectoral muscle disease and white striping which impair product appearance, and increased occurrence of problems related with the meat’s poor ability to hold water during processing and storage (PSE-like condition) as well as poor toughness and cohesiveness related to immaturity of intramuscular connective tissue. This paper is aimed at making a general statement of recent studies focusing on the relationship between muscle growth and meat quality issues in poultry

The influence of linseed on rabbit meat quality

A research was conducted to study the infl uence of the dietary use of whole linseed on rabbit meat quality. A total of 288 growing rabbits were fed ad libitum (from 55 to 81 d old) with a commercial diet (C) or experimental diets containing 3, 6, or 9% whole linseed (L3, L6 and L9, respectively). After slaughtering, L. lumborum muscles and rabbit meat hamburgers were used to determine pH, colour, cooking loss, total lipid content, fatty acid composition and induced TBARS. Hind leg muscles were analyzed for total lipid content, fatty acid composition and induced TBARS. Finally, a sensory test was carried out to establish the level of acceptability of rabbit meat hamburgers prepared with the meat batters stored for 3 or 6 months at −20°C. The use of linseed determined a lower content of total saturated fatty acid and a higher content of PUFA (P<0.01) in all types of meat. The PUFA n-3 content of the meat increased signifi cantly (P<0.01) with the increasing level of whole linseed in the diet, mainly due to the higher content of α-linolenic acid, which also determined a reduction of the n-6/n-3 PUFA ratio. The hamburgers prepared from L6 and L9 groups exhibited higher TBARS values in comparison with L3 and C. Furthermore, the cooking loss of hamburgers was lower in meat from rabbits fed the control diet (C), intermediate in L3 and higher in L6 and L9 (P<0.01). With regard to sensory analysis, the diet did not determine signifi cant differences in the acceptability of the hamburgers produced with frozen meat batters stored for 3 or 6 months. In general, the use of 3% linseed in diets for growing rabbits could be considered suitable for achieving both the enrichment of the meat with α-linolenic acid and maintaining good product quality characteristics

The use of marination to improve poultry meat quality

A study was conducted to determine the effect of marination on turkey breast meat quality traits. Breast meat samples were marinated with two types of solution (containing sodium tripolyphosphate, STPP or a commercial mix with sodium carbonate and citrate, COM) and three solution/meat ratios (14, 18, and 22%). Marination with STPP determined a higher increase of meat pH in comparison with COM (pH measured before and after marination = +0.20 vs. +0.14; P≤0.05). The marinade uptake and AK-shear values did not differ between solutions, whereas STPP determined a higher marinade retention (98.2 vs. 97.9%; P≤0.05) and a strong decrease of cooking loss (21.8 vs. 28.1%; P≤0.01) compared with COM. The increase of solution/meat ratio from 14 to 22% significantly raised meat pH, marinade uptake, and cooking loss of the meat. Taking into account both marinade uptake and cooking losses, the use of a 14% solution/meat ratio allowed to maximise processing yield. Overall, compared to non-marinated meat, marinated meat exhibited a higher lightness and yellowness, and a lower AK-shear value after cooking, confirming that this technique can be successfully employed to improve meat texture

Welfare aspects in rabbit rearing and transport

The review starts with the description of the rabbits' (Oryctolagus cuniculus) main habits and the current situation concerning the rabbit husbandry and management systems, as well as their effects on the welfare of these animals. As far as the intensive rabbit husbandry systems are concerned, the main problems are related to the time since rabbits have been domesticated and their adaptive capacity and coping styles as respects the farming environment and management systems. Both these aspects have implications in the present and future of rabbit rearing for different purposes. Examples are given on the effects of different housing and management systems on rabbit welfare, as well as examples of the ethological, physiological and productive indicators used to evaluate these effects. Transportation and, more generally, preslaughter phases including catching, fasting and lairage at the abattoir are considered major stressors for farmed rabbits and might have deleterious effects on health, well-being, performance, and finally, product quality. A general statement of the recent scientific studies considering the effects of pre-slaughter factors on physiological and productive measurements are reported. Finally, some indications in order to improve rabbit welfare, already present at the European level, are also outlined, together with the European Food Safety Authority opinions

Rabbit meat processing: historical perspective to future directions

[EN] In past centuries, because rabbits are relatively small, animals slaughtered for consumption were generally eaten immediately. However, since a single rabbit would offer little more product than could be consumed at one sitting, little effort was devoted to developing preserved rabbit products (such as salted or dried meat, sausages, etc.). For this reason, although there is a rich history of recipes using rabbit meat in the Mediterranean area, there are few traditional further-processed products. Nowadays, even though the processing industry is pushing more and more towards the introduction of more attractive products (i.e. ready meals, ready-to-cook, etc.) for consumers with little time for meal preparation, most rabbit meat worldwide is still sold as whole carcass or cut-up parts. This review analyses the main strength and weakness factors regarding the use of rabbit meat to manufacture further processed products. Bearing in mind these considerations, it then describes the more promising processing technologies for raw meat materials to obtain added-value products (marinated, formed, emulsified, coated, etc.) by exploiting rabbit meat¿s intrinsic characteristics, such as high protein/low fat content coupled with a balanced n-6 to n-3 PUFA ratio, low cholesterol and heme-iron content. Major trends in meat product formulation (modulation of lipid content and composition, use of novel antioxidants and salt reduction) are also discussed by highlighting strategies to provide healthier meat products meeting current nutritional needs. Finally, major packaging solutions for rabbit meat and meat products (ordinary and modified atmosphere, vacuum) are considered.Petracci, M.; Cavani, C. (2013). Rabbit meat processing: historical perspective to future directions. World Rabbit Science. 21(4):217-226. doi:10.4995/wrs.2013.1329SWORD21722621

Nitrogen availability in organic fertilizers from tannery and slaughterhouse by-products

Agriculture can play a primary role in the context of nutrients recovery by promoting the use of organic fertilizers (OFs). In order to use them efficiently, it is necessary to predict the nitrogen (N) bioavailability, which is a challenging matter due to the different physical-chemical characteristics of commercially available OFs. This study aims to evaluate hot-water extractable N as a rapid and cheap chemical indicator of bioavailable N. The trial was conducted on nine animal-based OFs obtained from different raw materials and treatment processes. They were fully characterized and the bioavailable N was determined by a 7-week soil incubation experiment. The results showed that hot-water extractable N underestimated bioavailable N in the case of leather meal based OFs; however, a significant linear regression fitting was achieved (R2 = 0.53). The C:N ratio was also assessed, which showed a negative correlation (−0.87) and a better linear regression fitting (R2 = 0.76) with the bioavailable N, but manifested some limitations in the prediction of leather meal based products. This experiment showed that both hot-water extractable N and C:N ratio can provide useful information for farmers in managing this class of OFs

Technical note: Estimation of real rabbit meat consumption in Italy

[EN] As in other livestock species, the annual per capita consumption of rabbit meat is currently estimated as the ratio of the total weight of carcasses available for consumption to the number of inhabitants of a certain region. The aim of this work was to establish conversion coefficients from carcass to dible lean meat and estimate real rabbit meat consumption in Italy. Accordingly, a total of 24 rabbits were slaughtered at 2 different ages to obtain carcasses representative of the main market categories in Northern Italy: medium-size (carcass weight of about 1.4 kg) and heavy-size (carcass weight of about 1.8 kg). Chilled carcasses were used to determine offal, dissectible fat, bone and meat weights and yields. Experimentally obtained conversion factors from carcass to edible lean meat and estimated meat waste percentage at retail and consumption levels were subsequently used to estimate the real per capita amount of rabbit meat consumed in Italy. The finding of this study revealed that, if compared to the medium-size group, heavy-size carcasses had higher lean meat yield for both intermediate (92.9 vs. 92.4%; P<0.05) and hind parts (84.3 vs. 79.1%; P<0.001). On the contrary, the meat yield of fore part was higher in the medium-size group (66.2 vs. 65.5%; P<0.001) compared to heavy-size carcasses. Eventually, overall meat yield was higher in heavy-size carcasses compared to medium-size ones (64.4 vs. 63.2%; P<0.001). By using these conversion factors and estimated overall losses at retailing and home-consumption (15%), we estimated that real per capita annual rabbit meat consumption is 0.50 kg in Italy, which is only 54% compared to the estimated apparent consumption (0.90 kg).Petracci, M.; Soglia, F.; Baldi, G.; Balzani, L.; Mudalal, S.; Cavani, C. (2018). Technical note: Estimation of real rabbit meat consumption in Italy. World Rabbit Science. 26(1):91-96. doi:10.4995/wrs.2018.7802SWORD919626

Detection of differentially expressed genes in broiler pectoralis major muscle affected by White Striping – Wooden Breast myopathies

Abstract White Striping and Wooden Breast (WS/WB) are abnormalities increasingly occurring in the fillets of high breast yield and growth rate chicken hybrids. These defects lead to consistent economic losses for poultry meat industry, as affected broiler fillets present an impaired visual appearance that negatively affects consumers' acceptability. Previous studies have highlighted in affected fillets a severely damaged muscle, showing profound inflammation, fibrosis, and lipidosis. The present study investigated the differentially expressed genes and pathways linked to the compositional changes observed in WS/WB breast muscles, in order to outline a more complete framework of the gene networks related to the occurrence of this complex pathological picture. The biochemical composition was performed on 20 pectoralis major samples obtained from high breast yield and growth rate broilers (10 affected vs. 10 normal) and 12 out of the 20 samples were used for the microarray gene expression profiling (6 affected vs. 6 normal). The obtained results indicate strong changes in muscle mineral composition, coupled to an increased deposition of fat. In addition, 204 differentially expressed genes (DEG) were found: 102 up-regulated and 102 down-regulated in affected breasts. The gene expression pathways found more altered in WS/WB muscles are those related to muscle development, polysaccharide metabolic processes, proteoglycans synthesis, inflammation, and calcium signaling pathway. On the whole, the findings suggest that a multifactorial and complex etiology is associated with the occurrence of WS/WB muscle abnormalities, contributing to further defining the transcription patterns associated with these myopathies

Effect of dietary thymol supplementation on lipid oxidation of chicken legs as related to storage conditions

The aim of this research was to evaluate the effect of dietary thymol supplementation on lipid oxidation of chicken leg meat during refrigerated shelf-life. Chickens belonging to Ross 308 hybrid were raised under experimental conditions up to 3 kg of live weight, using three dietary treatments: control (without supplementation, C), treatment 1 (C+0.1% w/w thymol supplementation, T1) and treatment 2 (C+0.2% w/w thymol supplementation, T2). After slaughtering, the chicken legs with skin were stored under conventional (CON) and modified atmosphere (MAP) at temperature of 2-4°C for 14 days. Lipid oxidation was monitored by the determination of primary (peroxide value, PV) and secondary (thiobarbituric acid reactive substances, TBARs) products at 3, 7, 10 and 14 days of storage under both CON and MAP conditions and compared with values found on fresh meat. The three different dietary treatments did not significantly affect the lipid oxidation parameters. PV ranged between 0.5-13.0, 0.7-13.0 and 1.0-11.0 meq O2/kg of lipid in poultry meat obtained with C, T1 and T2 diets, respectively. TBARs varied between 0.1-0.7, 0.1- 0.6 and 0.2-0.5 mg MDA/kg of meat in poultry meat obtained with C, T1 and T2 diets, respectively. On the other hand, interaction effect of diets and storage conditions were significant (P≤0.05) in PV formation, as it was delayed under MAP (maximum PV level after 2 and 5 days of storage in C and thymol-containing diets, respectively) with respect to conventional storage (PV apex after 2 days of storage). However, not significant differences (P≥0.05) were found on TBARs level as related to storage conditions. In conclusion, this study demonstrated that dietary thymol supplementation coupled to MAP storage conditions delay lipid oxidation of chicken legs with skin, thus improving their shelf-life