Superior Meat Quality Research Articles

Identification of two $alpha;RYR alleles and characterization of $alpha;RYR transcript variants in turkey skeletal muscle

We hypothesized that a mutation in the turkey skeletal muscle ryanodine receptor α isoform (αRYR) underlies turkey meat quality problems which are strikingly similar to pale, soft, exudative (PSE) pork. RT-PCR analysis of turkey αRYR mRNA covering amino acids 376 to 615 (numbered according to the human sequence) revealed at least three transcript variants. One transcript was homologous to the mammalian skeletal muscle RYR1 sequence in this region. The second transcript variant (AS-81) was characterized by the absence of 81 bases located at the beginning of exon 13, while the third transcript variant (AS-193) carried a deletion of 193 bases, corresponding to the entire exon 13. Two αRYR genomic DNA alleles (αRYR-I and αRYR-II) carrying the region of deletions in the turkey cDNA sequences were identified. Nucleotide sequence analysis demonstrated that the two alleles are identical in exon sequences but different in intron sequences. Comparison of genomic and cDNA sequences indicated that both AS-81 and AS-193 transcript variants probably arose via alternative splicing. Consistent with this mechanism, the last eight nucleotides of the 81 bases form a consensus sequence for a splice acceptor site. Both alleles could give rise to the AS-81 and AS-193 transcript variants via alternative splicing. Birds homozygous for αRYR-II tended to have superior meat quality indicators including significantly higher muscle pH at 15-min post mortem and lower muscle exudate at 24-h post mortem, compared to birds homozygous for αRYR-I.

Identification of two alphaRYR alleles and characterization of alphaRYR transcript variants in turkey skeletal muscle.

We hypothesized that a mutation in the turkey skeletal muscle ryanodine receptor alpha isoform (alphaRYR) underlies turkey meat quality problems which are strikingly similar to pale, soft, exudative (PSE) pork. RT-PCR analysis of turkey alphaRYR mRNA covering amino acids 376 to 615 (numbered according to the human sequence) revealed at least three transcript variants. One transcript was homologous to the mammalian skeletal muscle RYR1 sequence in this region. The second transcript variant (AS-81) was characterized by the absence of 81 bases located at the beginning of exon 13, while the third transcript variant (AS-193) carried a deletion of 193 bases, corresponding to the entire exon 13. Two alphaRYR genomic DNA alleles (alphaRYR-I and alphaRYR-II) carrying the region of deletions in the turkey cDNA sequences were identified. Nucleotide sequence analysis demonstrated that the two alleles are identical in exon sequences but different in intron sequences. Comparison of genomic and cDNA sequences indicated that both AS-81 and AS-193 transcript variants probably arose via alternative splicing. Consistent with this mechanism, the last eight nucleotides of the 81 bases form a consensus sequence for a splice acceptor site. Both alleles could give rise to the AS-81 and AS-193 transcript variants via alternative splicing. Birds homozygous for alphaRYR-II tended to have superior meat quality indicators including significantly higher muscle pH at 15-min post mortem and lower muscle exudate at 24-h post mortem, compared to birds homozygous for alphaRYR-I.

Relationships of myosin heavy chain fibre types to meat quality traits in traditional and modern pigs

Porcine skeletal muscle fibres were molecularly classified, using in situ hybridisation and immunocytochemistry, into four types, according to the isoform of myosin heavy chain (MyHC) that was present in each fibre (MyHC slow/I, MyHC 2a, MyHC 2x and MyHC 2b). The relationship between MyHC fibre types and meat quality traits between two phenotypically divergent muscles [longissimus dorsi (LD) and psoas], and between the same muscles of different breeds (traditional Berkshire and Tamworth, and modern Duroc-based and Large White-based) were examined. We found that the greater abundance of fast oxidative-glycolytic MyHC 2a and 2x fibres in the psoas was associated with superior meat quality traits, and that the greater presence of fast glycolytic MyHC 2b fibres in the LD could account for less favourable quality traits, both in terms of pH, drip loss, grain, colour, yield force and work done. Although significant correlations were found between specific fibre types and quality traits, within either the psoas or LD muscle of some breeds, no consistent correlation was found across both muscles and all breeds. This finding was in line with the view that a given fibre type could have considerable differences in phenotype between breeds, and between muscles. The observed inverse compositional and functional-meat quality relationship between MyHC 2b and 2x fibres, and MyHC 2b and 2a fibres could form a basis of fibre type manipulation to improve meat quality.

Effect of vitamin E on improving fresh pork quality in Berkshire- and Hampshire-sired pigs.

This study was designed to evaluate the effects of vitamin E supplementation on pork quality of two genotypes with distinct differences in pork quality traits. Pigs (n = 240; BW = 87 +/- 0.35 kg) were allotted by weight to one of 20 treatments (4 pens/treatment, 3 pigs/pen) in a 2 x 2 x 5 factorial randomized complete block design. Factors included 1) genotype (Berkshire or Hampshire sired), 2) sex (gilts or barrows), and 3) vitamin E level (12.1, 54.7, 98.8, 174.0, and 350.6 IU of vitamin E/kg diet). Hampshire-sired pigs had greater average daily gain (1.05 vs 0.98 kg) and gain:feed (0.30 vs 0.27) and less average daily feed intake (ADFI) (3.46 vs 3.62 kg) than Berkshire-sired pigs (P < 0.001) for the 6-wk study. Hampshire-sired barrows consumed more feed (3.54 vs 3.38 kg/d) and were less efficient (0.29 vs 0.31) than Hampshire-sired gilts (P < 0.05), but this sex difference was not observed in Berkshire-sired pigs (interaction, P < 0.05). Berkshire-sired pigs had greater backfat (34.1 vs 21.1 mm; P < 0.001), reduced longissimus muscle area (37.6 vs 46.3 cm2; P < 0.001), reduced lean percentage (53.0 vs 55.8; P < 0.001), and a greater head-on yield (79.8 vs 79.2; P < 0.05). Vitamin E increased (P < 0.05) ADFI linearly (P < 0.05), but had no effects on carcass composition. Loin chops from Hampshire-sired pigs had reduced ultimate pH (5.64 vs 5.91), greater drip loss (92.2 vs 66.3 mg), and increased Minolta L* (52.6 vs 48.6), a* (8.9 vs 7.5), and b* (6.9 vs 5.2) values compared to Berkshire-sired pigs (P < 0.001). Vitamin E had no effect on pH, temperature, drip loss, and L* or a* values, but tended (P < 0.07) to increase b* values linearly (P < 0.06). Oxidation as indicated by thiobarbituric acid reactive substances (TBARS) was greatest in Hampshire-sired gilts at the lowest level of vitamin E, and decreased linearly (P < 0.001) with additional vitamin E. However, TBARS responded in a cubic fashion (P < 0.05) to vitamin E in Hampshire-sired barrows and were not affected in Berkshire-sired gilts or barrows (three-way interaction, P < 0.02). Hampshire-sired pigs had greater TBARS than Berkshire-sired pigs (0.053 vs 0.047 mg malondialdehyde equivalents/kg). Vitamin E supplementation increased serum concentrations of vitamin E on d 21 (1.06 to 4.79 microg/mL) and d 42 (1.02 to 2.82 microg/mL) and increased tissue concentrations of vitamin E (1.99 to 4.83 microg/g) linearly (P < 0.001). Vitamin E supplementation was not effective in improving fresh meat quality in genotypes with poor or superior meat quality traits.

CONSERVATION AND UTILIZATION OF BEEF CATTLE GENETIC RESOURCES IN JAPAN

SUMMARYThere are four cattle beef breeds in Japan: Japanese Black, Japanese Brawn, Japanese Poll and Japanese Shorthorn. These breeds were crossed with European breeds in the early 1900's. As a result of introducing European blood, Japanese beef cattle have an expanded and more diverse gene pool. Furthermore, both the breed used for crossing and the selection criteria employed varied significantly from prefecture to prefecture Consequently, a number of distinct strains have been established. At present, however, the genetic diversity is becoming increasingly concentrated around a limited number of strains noted for their superior meat quality. From the genetic conservation view point, it is necessary to stock minor strains by frozen semen and embryos for future domands of genetic resources. This paper discusses the conservation and current utilization of beef cattle genetic resources in Japan.

Description of carcass classification goals and the current situation in South Africa

Carcass classification is an essential part of efficient animal production, price fixing and meeting consumer demands. Carcass classification (or grading) is based on the description of carcasses by means of clearly defined characteristics that are of prime importance to the meat industry, retailers and consumers. Significant variation exists in carcass composition and quality due to the effects of species, age, maturity type, sex and interaction effects with animal production systems. A number of extrinsic and intrinsic factors affects carcass and meat quality and the purpose of carcass classification in South Africa is to classify carcasses to ensure more consistent meat quality, composition and consumer satisfaction. Although carcass inspection is compulsory in South Africa, carcass classification is not a requisite at all South African abattoirs. South Africa employed a carcass grading system from 1944 to 1992, which was replaced by a carcass classification system in 1992. Carcass classification differs fundamentally from carcass grading. In carcass classification there is a shift of emphasis to classifying carcasses in order to provide the meat industry and consumers with a choice of different types of carcasses in terms of carcass composition and physical attributes, while there is no indication of perceived quality as is provided in a grading system. In a carcass grading system, an indication is provided of standard, prime and superior carcass grades which relate to standard, prime and superior meat quality. The conceptual basis of the carcass classification system is therefore based on the principle that producers, retailers and consumers differ in terms of their perceptions and expectations of carcass and meat quality, and subsequent eating experience. More recently it has become apparent that the current classification system is being used as a grading system due to the use of preferred classes, which defeats the original purpose of a classification system. Furthermore, recent research suggests that the variation within carcass classification categories has increased considerably due to differences between livestock breeds and types, animal production systems and the use of modern feedstuffs and growth enhancing technologies. The purpose of this paper is to review the characteristics and goals of the current South African carcass classification system, grading systems in other countries and the implications for effective marketing, price fixing and consumer satisfaction based on the complex cycle from ‘farm to fork’.Keywords: Carcass classification, carcass grading, beef, sheep, marketing, consumer acceptance

The Relation of Age at Sexual Maturity to Some Developmental Characters

THE onset of sexual maturity produces a profound effect on the physiology of the fowl and subsequent developmental processes. The fact has long been known that age at sexual maturity has a significant influence on the development of feather pigments in such breeds as Barred Plymouth Rocks (Martin, 1929) and Rhode Island Reds (Hays, 1932). More recently because of the demand for chickens of superior meat quality, the effect of age at sexual maturity on such characters as rate of growth and adult weight requires attention.A considerable body of data collected a few years ago on Rhode Island Reds may serve a useful purpose in this connection.DATA AVAILABLE FOR STUDYThree generations of pedigreed Rhode Island Red pullets hatched in 1934, 1935, and 1936 in several experiments are available for study. Body weight was taken at monthly intervals throughout the laying year on 1,859 individuals, beginning when the .