Animal factors affecting the meat quality of Australian lamb meat

This paper integrates the key industry findings from the twelve preceding papers in this special edition of Meat science. In so doing, various animal factors important for the quality of Australian lamb meat are highlighted for sensory, visual appeal and human health attributes. Intramuscular fat concentration (IMF) was found to be a key element of eating quality that interacts both positively and negatively with a range of other factors. Shear force, IMF, colour stability and docosahexaenoic acid (DHA) will likely respond to genetic selection whilst other omega-3 fatty acids require nutritional intervention. Australian lamb meat can generally be regarded as a good source of the minerals iron and zinc; and a source of omega 3 fatty acids when finished on green pasture. Breeding priorities for meat quality will likely depend on breed type with improvement of meat colour stability more important for the wool focused Merino breed and improvement of sensory quality for the terminal sire breeds.     

Genetic parameters for meat and fat quality and carcass composition traits in Iberian pigs

Carcass composition and quality traits were measured in heavy Iberian pigs after extensive handling. The weights of trimmed hams, forelegs and loins were recorded on 2170–2553 pigs, intramuscular fat content in M. longissimus (IMF) on 1489 and percentages of palmitic, stearic, oleic and linoleic acids in the subcutaneous fat on 1495 pigs, slaughtered at about 160 kg live weight. For carcass traits the heritability estimates ranged from 0.28 to 0.41. Heritability estimate for IMF was 0.25 and estimates of heritability for the measured fatty acids ranged from 0.29 to 0.41. The estimated genetic correlations (rg) suggest antagonism between IMF and weights of hams (rg=−0.30) and loins (rg=−0.33) and an unfavourable positive association of premium cuts with linoleic acid content (rg: 0.31–0.57). The incorporation of meat and fat quality traits to the selection aims of the breeding scheme for Iberian pigs seems advisable.     

Translating science into the next generation meat quality program for Australian lamb

This paper introduces a series of papers in the form of a special edition that reports phenotypic analyses done in parallel with genotypic analyses for the Australian Sheep Industry Cooperative Research Centre (Sheep CRC) using data generated from the information nucleus flock (INF). This has allowed new knowledge to be gained of the genetic, environment and management factors that impact on the carcase and eating quality, visual appeal, odour and health attributes of Australian lamb meat. The research described involved close collaboration with commercial partners across the supply chain in the sire breeding as well as the meat processing industries. This approach has enabled timely delivery and adoption of research results to industry in an unprecedented way and provides a good model for future research.     

Genetic parameters of carcass and meat quality traits of double muscled Piemontese cattle

Genetic parameters of meat quality (MQ) were estimated on Longissimus thoracis muscle of 1208 Piemontese young bulls, progeny of 109 AI sires. Carcass weight (CW), conformation (EUS) and pH (pH24h) were recorded at 24h and lightness (L*), redness (a*), yellowness (b*), pH (pH8d), drip loss (DL), cooking loss (CL) and shear force (SF) were assessed. The heritability (h(2)) of pH24h was very low (0.06), but h2 of pH8d was markedly higher (0.42). Heritability was 0.32, 0.33, and, 0.14, for L*, a* and b*, respectively, whereas was 0.24, 0.07 and 0.14, for DL, CL, and SF, respectively. The two pH measures showed opposite genetic relationships with color measures. Genetic correlations of DL and CL were positive with L* and b* and negative with a*. Genetic correlations between carcass traits and MQ suggest that animals with superior growth potential tend to exhibit reduced EUS scores and pale meat with lower tenderness and water holding capacity. Conversely, improvement of EUS score through selection would lead to light, bright, and tender meat with enhanced water holding capacity.     

Prediction of lamb meat quality traits based on muscle biopsy fibre typing

The aim of the experiment described in this paper was to determine the relationship between muscle fibre type and meat quality.

Two indicator muscles, the Stylohyoïdeus and the Scutulo auricularis superficialis accessorius, were biopsied on one-month-old lambs and used as an index to select the animals of the redder and of the whiter metabolic types among the lamb population studied. Evaluation of the organoleptic qualities of meats from two groups was performed on the Longissimus dorsi muscle by a taste panel.

The results of the taste panel evaluation suggest, on one hand, that the meat from the redder animals is juicier and has a more intense flavour than that from the whiter. On the other hand, it appears possible to obtain an in vivo prediction of lamb meat quality based on muscle biopsy fibre typing.     

Genetic parameters for methane emission traits in Australian dairy cows

Methane is a greenhouse gas of high interest to the dairy industry, with 57% of Australia's dairy emissions attributed to enteric methane. Enteric methane emissions also constitute a loss of approximately 6.5% of ingested energy. Genetic selection offers a unique mitigation strategy to decrease the methane emissions of dairy cattle, while simultaneously improving their energy efficiency. Breeding objectives should focus on improving the overall sustainability of dairy cattle by reducing methane emissions without negatively affecting important economic traits. Common definitions for methane production, methane yield, and methane intensity are widely accepted, but there is not yet consensus for the most appropriate method to calculate residual methane production, as the different methods have not been compared. In this study, we examined 9 definitions of residual methane production. Records of individual cow methane, dry matter intake (DMI), and energy corrected milk (ECM) were obtained from 379 animals and measured over a 5-d period from 12 batches across 5 yr using the SF₆ tracer method and an electronic feed recording system, respectively. The 9 methods of calculating residual methane involved genetic and phenotypic regression of methane production on a combination of DMI and ECM corrected for days in milk, parity, and experimental batch using phenotypes or direct genomic values. As direct genomic values (DGV) for DMI are not routinely evaluated in Australia at this time, DGV for FeedSaved, which is derived from DGV for residual feed intake and estimated breeding value for bodyweight, were used. Heritability estimates were calculated using univariate models, and correlations were estimated using bivariate models corrected for the fixed effects of year-batch, days in milk, and lactation number, and fitted using a genomic relationship matrix. Residual methane production candidate traits had low to moderate heritability (0.10 ± 0.09 to 0.21 ± 0.10), with residual methane production corrected for ECM being the highest. All definitions of residual methane were highly correlated phenotypically (>0.87) and genetically (>0.79) with one another and moderately to highly with other methane candidate traits (>0.59), with high standard errors. The results suggest that direct selection for a residual methane production trait would result in indirect, favorable improvement in all other methane traits. The high standard errors highlight the importance of expanding data sets by measuring more animals for their methane emissions and DMI, or through exploration of proxy traits and combining data via international collaboration.     

Associations of sire estimated breeding values and objective meat quality measurements with sensory scores in Australian lamb

The impact of selecting for lean meat yield using breeding values for increased eye muscle depth (PEMD) and decreased fat depth (PFAT) on the consumer acceptance of lamb meat was evaluated. Consumer sensory scores (tenderness, juiciness, flavour, odour, overall liking) were obtained for the longissimus lumborum (loin) and semimembranosus (topside) muscles of 1471 lambs. On average loin samples were more acceptable for consumers. Sensory scores increased with higher IMF levels, with lower shear force levels, and when animals were younger and less muscular. Increasing PEMD decreased tenderness, overall liking and flavour scores in both muscles, and decreasing PFAT reduced tenderness within the loin samples only. This negative impact of PEMD and PFAT is not solely driven through the phenotypic impact of IMF and shear force on sensory scores. Our results confirm the growing concerns that selecting for lean meat yield would reduce consumer eating quality, and highlight that careful monitoring of selection programmes is needed to maintain lamb eating quality.     

Microbiological quality of Australian sheep meat

Microbiological quality of sheep carcasses and boneless sheep meat produced in Australia was surveyed during the period June to November 1998. Sponge samples were collected from 917 carcasses, and meat samples were drilled from 467 cartons of frozen boneless meat. Carcass and boneless meat samples were respectively collected from 7 and 10 establishments that concentrated on export, and from 36 and 5 establishments supplying the Australian domestic market of which 31 were very small plants slaughtering cattle and sheep but no more than 1,200 sheep equivalents per week. The mean log total viable counts were 3.55/cm2 and 3.30/g for carcasses and boneless meat, respectively. Escherichia coli was detected on 29.2% of carcasses and 24.5% of boneless meat samples and coagulase-positive staphylococci on 24.1% of carcasses, and 38.6% of boneless meat samples. Salmonella was detected on 0.1% of carcasses and 1.3% of boneless meat samples. E. coli O157:H7 was recovered from 0.7% of carcasses and 1.3% of boneless sheep meat. There were statistically significant differences between establishment types for some microbiological criteria, although there were no significant differences in prevalence of Salmonella or E. coli O157:H7 between establishment types. While there were differences in sampling and microbiological techniques between this study and another conducted in 1993 to 1994 that require detailed consideration, there were small but significant improvements in several microbiological criteria for boneless meat. While data that would allow for comparison of carcass data were not gathered, it is unlikely that improvements in the microbiological quality of boneless sheep meat could accrue without improvements to carcasses.     

Effect of electrical stunning on meat quality of lamb

The effects of stunning on both initial and up to 2 weeks post mortem storage meat quality of Spanish Manchega breed lamb were studied. Twenty-four lambs were distributed into two groups. The first group (US; n =12) were slaughtered without previous stunning. In the second group (ES; n =12) animals were electrically stunned. Meat quality was assessed by examining pH, colour as L*, a*, b* values, water holding capacity (WHC) and shear force (SF). Stunning did not affect any parameter studied in the first 24 h post mortem. There were increasing differences between groups in pH (P<0.001) from 5 days onwards. In general stunning did not have an effect on WHC, SF and colour parameters. Ageing of meat affected SF in the ES group but not in the US one; however, there were no significant differences between treatments at any of the ageing times.     

Genetic parameters for buffalo milk yield and milk quality traits using Bayesian inference

The availability of accurate genetic parameters for important economic traits in milking buffaloes is critical for implementation of a genetic evaluation program. In the present study, heritabilities and genetic correlations for fat (FY305), protein (PY305), and milk (MY305) yields, milk fat (%F) and protein (%P) percentages, and SCS were estimated using Bayesian methodology. A total of 4,907 lactations from 1,985 cows were used. The (co)variance components were estimated using multiple-trait analysis by Bayesian inference method, applying an animal model, through Gibbs sampling. The model included the fixed effects of contemporary groups (herd-year and calving season), number of milking (2 levels), and age of cow at calving as (co)variable (quadratic and linear effect). The additive genetic, permanent environmental, and residual effects were included as random effects in the model. The posterior means of heritability distributions for MY305, FY305, PY305, %F, P%, and SCS were 0.22, 0.21, 0.23, 0.33, 0.39, and 0.26, respectively. The genetic correlation estimates ranged from −0.13 (between %P and SCS) to 0.94 (between MY305 and PY305). The permanent environmental correlation estimates ranged from −0.38 (between MY305 and %P) to 0.97 (between MY305 and PY305). Residual and phenotypic correlation estimates ranged from −0.26 (between PY305 and SCS) to 0.97 (between MY305 and PY305) and from −0.26 (between MY305 and SCS) to 0.97 (between MY305 and PY305), respectively. Milk yield, milk components, and milk somatic cells counts have enough genetic variation for selection purposes. The genetic correlation estimates suggest that milk components and milk somatic cell counts would be only slightly affected if increasing milk yield were the selection goal. Selecting to increase FY305 or PY305 will also increase MY305, %P, and %F.     

Influence of age at slaughter, rearing technique and pre-slaughter treatment on some quality traits of lamb meat

The influences of rearing technique and age on muscle fibre type, and of rearing technique, age and pre-slaughter transport on the meat quality characteristics of sheep were investigated using thirty lambs of a Bulgarian coarse-fleeced breed (Karakatchanska). The animals were reared on pasture or in barns and slaughtered at 22 or 30 weeks of age. Muscle fibre type and meat quality were studied in three muscles of different metabolic type—Longissimus dorsi (LD), Supraspinatus (SS) and Rectus abdominis (RA). Fibre type distribution was influenced by age but not by rearing technique. Pigment content of muscles was higher in older animals. Water binding capacity (WBC) increased—and cooking loss decreased—with age. There was an interaction between muscle and pre-slaughter stress with respect to pH, the latter being increased in SS muscle, as was WBC. Cooking loss was decreased by transport stress in the three muscles and by pre-slaughter stress. However, meat organoleptic characteristics (flavour, tenderness and juiciness, as judged by a taste panel) were not influenced by age, rearing technique or pre-slaughter treatment.     

Effect of artificial rearing on lamb welfare and meat quality

Twenty male Comisana lambs were equally divided into two groups. Ten subjects were artificially reared, 10 others were ewe reared and used as control. Unseparated control animals displayed increased cellular immune response to a percutaneous injection of phytohemagglutinin (P<0.001). During the open field test, ewe-reared lambs showed a higher number of flight attempts (P<0.01). Carcass yield were higher for artificially reared animals (P<0.05). Conversely, legs of ewe-reared animals had significantly more fat (P<0.05) and a higher content of saturated fatty acids (P<0.001). Polyunsaturated fatty acid content was higher in artificially reared lamb meat (P<0.01), although the ratio n-6/n-3 was well above the recommended values. The triangle test showed a significant difference in sensory analysis between the two products (P<0.05). Finally, for both rearing systems legs without subcutaneous fat showed a higher percentage of polyunsaturated fatty acids and a corresponding lower content of saturated fatty acids (P<0.001).     

Chemical composition and quality attributes of goat meat and lamb

Chemically, goat meat had significantly (P < 0·05) less intramuscular fat and significantly (P < 0·001) more moisture than lamb. The sarcoplasmic protein concentration of the goat meat was significantly (P < 0·001) greater than that of lamb while the myofibrillar protein concentration was similar in the two species.

Goat meat was darker red in colour than lamb. It had significantly (P < 0·001) superior water-holding capacity and less cooking losses than lamb. Meat flavour was significantly (P < 0·05) less strong in goat meat than in lamb.     

Effect of different stunning systems on meat quality of light lamb

The present study was proposed to compare the effect that different types of stunning (TS) had on the quality of refrigerated meat from light lambs of the Spanish Manchega breed at 24 h and 7 days post-mortem. Lambs were electrically stunned (ESL; n = 10), using CO₂ (GSL; n = 10) or slaughtered without previous stunning (USL; n = 10). Measurements on meat quality were carried out by evaluating pH, colour coordinates (L^*, a^*, b^*), water holding capacity (WHC), cooking loss (CL), shear force (SF) and drip loss (DL). At 24 h post-mortem, no significant differences were found in any of the variables studied. However, at 7 days post-mortem, meat quality was affected by the different TS: pH, CL and DL were lower (P < 0.001) in the USL group and GSL obtained the lowest a^* (redness) and b^* (yellowness) values (P < 0.01) than in the other groups. Ageing of meat affected SF in the ESL group (P < 0.01), although there were no significant differences due to treatments at any of the ageing times.     

Microbiological quality of Australian sheep meat in 2004

The third national baseline microbiological survey of Australian sheep carcases and frozen boneless sheep meat was conducted in 2004. Carcases (n=1117) sampled at 20 slaughter establishments were found to have a mean log total viable count (TVC, 25°C) of 2.28 cfu/cm(2) and Escherichia coli was isolated from 43.0% carcases with a mean log 0.03cfu/cm(2) on positive samples. In samples from 10 boning (fabrication) plants (n=560) the mean log TVC for frozen boneless sheep meat was 1.85cfu/g and the mean log count for the 8.2% of samples with detectable E. coli was 1.39cfu/g. E. coli O157:H7 was isolated from 6/1117 carcases and from 1/560 boneless samples. Salmonella was isolated from 0/1117 carcases and from 3/560 samples of boneless product. Campylobacter sp. were isolated from 4/1117 carcases and from 1/560 boneless samples. Coagulase positive staphylococci were isolated from 23.4% to 32.7% of carcases and boneless sheep meat samples, respectively, with positive samples having a mean log count of 0.93cfu/cm(2) and 1.14cfu/g, respectively. The low level of bacteria described here is consistent with a very low risk to human health due to bacterial hazards in Australian sheep meat.     

Effects of two transport systems on lamb welfare and meat quality

The aim of this study was to analyse the effect of a direct transport system (DTS) versus transport with a logistic stopover system (TLS) on lamb welfare and meat quality at two seasons. A total of 96 lambs were sampled in a 2 × 2 × 2 factorial design, testing two transport systems and two seasons (summer and winter), with two replicates in each season. Significant interactions (P ≤ 0.05) between transport system and season in both welfare and meat quality were found. In general, lambs subjected to direct transport and logistic stopover during winter had a more intense stress response and poorer meat quality than lambs transported during summer. However, direct transport during the cold season seemed to be the most stressful, compared to the rest of the groups, which was reflected in significantly higher levels of cortisol, lactate, glucose, ratio of N/L, higher pH24 and darker and tougher meat.     

Effects of two transport systems on lamb welfare and meat quality

The aim of this study was to analyse the effect of a direct transport system (DTS) versus transport with a logistic stopover system (TLS) on lamb welfare and meat quality at two seasons. A total of 96 lambs were sampled in a 2×2×2 factorial design, testing two transport systems and two seasons (summer and winter), with two replicates in each season. Significant interactions (P≤0.05) between transport system and season in both welfare and meat quality were found. In general, lambs subjected to direct transport and logistic stopover during winter had a more intense stress response and poorer meat quality than lambs transported during summer. However, direct transport during the cold season seemed to be the most stressful, compared to the rest of the groups, which was reflected in significantly higher levels of cortisol, lactate, glucose, ratio of N/L, higher pH24 and darker and tougher meat.     

辐照对肉品微生物及牛羊肉品质的影响

研究了不同温度、不同包装形式下辐照处理对牛羊肉货架期和营养品质的影响。结果表明,产品经真空包装后,2~4.0KGy低温辐照,产品贮藏在2±1℃环境下,牛羊肉的货架期可达到60d。     

Assessment of commercial lamb meat quality by British and Spanish taste panels

Trained sensory panels in Britain and Spain assessed loin meat from commercial lambs purchased in Spain, which included Welsh lamb (imported from Britain) and two Spanish breeds (Merino and Rasa Aragonesa). The British panel also assessed British lamb purchased in local butcher shops and supermarkets. Sensory panels, in each country, received meat from the same lambs and used their local methods of cooking and assessment. Spanish panels used unstructured line scales to measure lamb odour intensity, tenderness, juiciness, lamb flavour intensity and two hedonic scales of flavour liking and overall liking. The British panel used 8 point category scales with the same attributes. Results from both panels in objective parameters were in agreement, hence showing that different trained sensory panels may arrive at the same conclusion. However, when panellists were allowed to make hedonic judgements (preference), the British panel preferred British lamb and the Spanish panel preferred Spanish lamb. This finding has important consequences for lamb producers who export their lambs and demonstrates that the underlying reasons for different preferences should be investigated. Production variables are discussed in relation to their influence on lamb eating quality and as a way to tailor lamb eating quality attributes familiar to consumers in the importing country.