Preslaughter handling of pigs and the effect on heart rate, meat quality, including tenderness, and sarcoplasmic reticulum Ca(2+) transport

Poultry Response to Heat Stress: Its Physiological, Metabolic, and Genetic Implications on Meat Production and Quality Including Strategies to Improve Broiler Production in a Warming World

The continuous increase in poultry production over the last decades to meet the high growing demand and provide food security has attracted much concern due to the recent negative impacts of the most challenging environmental stressor, heat stress (HS), on birds. The poultry industry has responded by adopting different environmental strategies such as the use of environmentally controlled sheds and modern ventilation systems. However, such strategies are not long-term solutions and it cost so much for farmers to practice. The detrimental effects of HS include the reduction in growth, deterioration of meat quality as it reduces water-holding capacity, pH and increases drip loss in meat consequently changing the normal color, taste and texture of chicken meat. HS causes poor meat quality by impairing protein synthesis and augmenting undesirable fat in meat. Studies previously conducted show that HS negatively affects the skeletal muscle growth and development by changing its effects on myogenic regulatory factors, insulin growth factor-1, and heat-shock proteins. The focus of this article is in 3-fold: (1) to identify the mechanism of heat stress that causes meat production and quality loss in chicken; (2) to discuss the physiological, metabolic and genetic changes triggered by HS causing setback to the world poultry industry; (3) to identify the research gaps to be addressed in future studies.

Acetylation and Phosphorylation of Proteins Affect Energy Metabolism and Pork Quality

Preslaughter handling has been shown to significantly affect meat quality, but the mechanisms are not fully understood. In this study, we investigated protein phosphorylation and acetylation in pig muscles at early postmortem time and their associations with meat quality attributes. Thirty pigs were randomly assigned to traditional (TH, n = 15) or mild handling (MH, n = 15). Compared with TH, MH reduced the incidence of pale, soft, and exudative (PSE) or dark, firm, and dry (DFD) pork. MH induced 65 and 20 peptides that match with 39 and 12 proteins to be more highly phosphorylated and acetylated, respectively. Creatine kinase, β-enolase, α-1,4-glucan phosphorylase, tropomyosin, and myosin heavy chain isoforms 1, 4, and 7 were found to be simultaneously phosphorylated and acetylated, which may involve glycolysis, tight junctions, and muscle contraction. The phosphorylation and acetylation levels of differential proteins showed significant correlations with meat quality traits. These findings indicate that preslaughter MH can improve meat quality by regulating protein phosphorylation and acetylation involving energy metabolism in muscle.

Combined effects of aging and low temperature, long time heating on pork toughness

The combined effects of aging and low temperature, long time heating (LTLT) on meat toughness were investigated. Pork loins were heated at 53 or 58 °C for up to 20 h, and shear force values, cooking loss, moisture content, collagen solubility, electrophoresis of myofibrillar proteins were determined. Structural changes in perimysium were also observed by light microscopy and scanning electron microscopy (SEM). Results showed that aging and LTLT cooking independently affected meat toughness, and higher temperature or longer time were required to decrease toughness of one-day aged meat to the same level as in 10-day aged meat. Collagen solubilization is suggested as the main reason for the tenderization effect of LTLT. Myofibrillar proteolysis might not occur during LTLT cooking, and will not be contributing to meat tenderness.

Invited review: Measurable biomarkers linked to meat quality from different pig production systems

Abstract. Biological processes underlie all livestock traits, including post-mortem meat quality traits. Biomarkers are molecular components of the biological processes showing differential expression associated with the phenotype of the trait. The phenotypes of the meat quality traits are determined by the animal's genotype interacting with the environment affecting the expression of the genome. The omics technologies enable measuring the expression of the genome at all levels: transcriptome, proteome, and metabolome. Associations between the phenotype of the traits and expressions measured with the omics techniques are a first step in developing biomarkers. Biomarkers enable the monitoring, diagnosis, and prediction of changes in meat quality related to external (environmental, e.g. feed and animal management conditions) stimuli and interactions with the genotype. In this paper we review the development of biomarkers for meat quality of pigs in diverse pig breeds, environments, and pork production chains.

PIG SLAUGHTERING IN SOUTHWESTERN NIGERIA: PECULIARITIES, ANIMAL WELFARE CONCERNS AND PUBLIC HEALTH IMPLICATIONS

BACKGROUND

Pig slaughtering methods influence the quality of pig products and also serves as a critical point for the control of zoonosis and other food-borne infections. This study aimed at assessing the peculiarities, the animal welfare concerns and the public health implications of pig slaughtering activities was conducted on three major abattoirs in Southwestern Nigeria.

MATERIALS AND METHODS

Information on pre-slaughter handling, slaughtering and carcass processing were obtained by observation over a continuous 2-week period of normal abattoir activities in each abattoir by the authors. Structured questionnaires were administered and focus group interviews were conducted to obtain information from the abattoir workers and health officials. Data were analyzed using descriptive statistics.

RESULT AND CONCLUSION

The pig slaughtering methods in the three locations vary considerably with some identified areas of animal welfare concerns which include inhumane transportation, restraining, lairaging, and stunning practices.s. These amount to excessive stress and poor animal welfare. The abattoir findings with public health implications include floor slaughtering, inadequate water supply, excessive biological intrusions, poor environmental hygiene, poor waste disposal and failure of abattoir workers to use protective clothing. The implications of the findings are discussed.

Effects of transport stress and rest before slaughter on blood parameters and meat quality of ducks

Zhu, Z., Chen, Y., Huang, Z., Zhang, Y., Xu, Q., Tong, Y., Zhai, F., Chang, G. and Chen, G. 2014. Effects of transport stress and rest before slaughter on blood parameters and meat quality of ducks. Can. J. Anim. Sci. 94: 595–600. Ducks have been transported to be slaughtered at centralized locations since the 2013 avian influenza A (H7N9) epidemics in China. It is unavoidable that a certain amount of stress will occur during the transportation. We investigated the effects of transport stress and rest before slaughter on blood parameters and meat quality in ducks. Pekin ducks (42 d old) were randomly divided into six groups. Each group had five replicates, with four ducks in each replicate. The experimental design included the variables transport time and rest time before slaughter. Transport distance categories were short-distance (1 h transport; n=20), medium-distance (2 h transport; n=20) and long-distance (3 h transport; n=20) transport. Rest time was categorized as short (0.5 h; n=20) or long (2 h; n=20) periods of rest. Blood samples and meat samples were collected after transport or after the post-transport rest period. Blood indicators (triiodothyronine, thyroxine, insulin, glutamic-pyruvic transaminase, aspartate transaminase, creatine kinase, and glutathione peroxidase) were measured using enzyme-linked immunosorbent assay (ELISA) kits. Meat quality characteristics (meat component, pH, malondialdehyde, and protein carbonyl) were also measured. Triiodothyronine, thyroxine, aminotransferase, glutamic-oxaloacetic transaminase, creatine kinase, glutathione peroxidase, pH, malondialdehyde, and protein carbonyl values changed significantly in ducks exposed to the medium-distance transport treatment. Stress indicators improved and meat quality returned to normal by the end of a 2-h pre-slaughter rest. These results indicate that a 2-h transport causes serious stress in ducks. A 2-h rest before slaughter mitigates these adverse effects.

Oxidative stress-induced metabolic changes in mouse C2C12 myotubes studied with high-resolution 13C, 1H, and 31P NMR spectroscopy

In this study, stress in relation to slaughter was investigated in a model system by the use of (13)C, (1)H, and (31)P nuclear magnetic resonance (NMR) spectroscopy for elucidating changes in the metabolites in C2C12 myotubes exposed to H(2)O(2)-induced stress. Oxidative stress resulted in lower levels of several metabolites, mainly amino acids; however, higher levels of alanine were apparent in the (13)C spectra after incubation with [(13)C(1)]glucose. In the (13)C spectra [(13)C(3)]lactate tended to increase after exposure to increasing concentrations of H(2)O(2); conversely, a tendency to lower levels of the unlabeled ((12)C) lactate were identified in the (1)H spectra after stress exposure. These data indicate an increase in de novo synthesis of alanine, concomitant with a release of lactate from the myotubes to the medium at oxidative stress conditions. The changes in the metabolite levels could possibly be useful as markers for meat quality traits.

Effects of loading methods on rabbit welfare and meat quality

The effects of different loading methods on the welfare, carcass characteristics and meat quality traits of hybrid commercial rabbits were investigated. 384 male rabbits, 82 days old, were transported from the farm to the slaughterhouse. At the farm, 192 rabbits were loaded onto the truck smoothly (S) and 192 rabbits were loaded roughly (R). The S loading method consisted of carefully placing each rabbit into the transport crates. In the R method, the loading was hurriedly and carelessly executed by the transport operator, throwing each animal into the crates fixed on the truck. Live weight before and after transport as well as slaughter data were recorded for each rabbit, and a subset of 80 carcasses were evaluated for meat quality. Blood samples from 80 rabbits were analysed for haematological and biochemical parameters. A significant neutrophilia (P<0.001), lymphocytopaenia (P<0.001) and an increase in serum aspartate aminotransferase (AST) (P<0.01), alanine aminotransferase (ALT) (P<0.001) and creatine kinase (CK) activities (P<0.001) were recorded in all rabbits after transport, independent of the loading method. A twofold increase in serum corticosterone concentration (6.23 vs. 14.88 ng/mL; P=0.001) was observed in all rabbits following transport. Results suggest that the stress parameters analysed were more influenced by transport and handling itself rather than by the different loading methods. The results showed that there was no adverse effect of loading method on carcass traits. Furthermore, the stress condition evidenced by haematological and biochemical parameters prior to slaughter did not affect meat quality.