The effect of nutritional supplements on growth rate, stress responsiveness, muscle glycogen and meat tenderness in pastoral lambs

Microbial spoilage mechanisms of vacuum-packed lamb meat: A review

Lamb meat is an important export commodity, however chilled vacuum-packed (VP) lamb has approximately half the shelf-life of beef under the same storage conditions. This makes the industry more vulnerable to financial losses due to long shipping times and unexpected spoilage. Understanding the spoilage mechanisms of chilled VP lamb in relation to VP beef is important for developing effective strategies to extend the shelf-life of lamb. This review has discussed various key factors (i.e., pH, fat, and presence of bone) that have effects on microbial spoilage of VP lamb contributing to its shorter shelf-life relative to VP beef. A range of bacterial organisms and their metabolisms in relevance to lamb spoilage are also discussed. The data gap in the literature regarding the potential mechanisms of spoilage in VP red meat is highlighted. This review has provided the current understanding of key factors affecting the shelf-life of VP lamb relative to VP beef. It has also identified key areas of research to further understand the spoilage mechanisms of VP lamb. These include investigating the potential influence of fat and bone (including bone marrow) on the shelf-life, as well as assessing changes in the meat metabolome as the spoilage microbial community is developing using an integrated approach. Such new knowledge would aid the development of effective approaches to extend the shelf-life of VP lamb.

The effect of using diet supplementation based on argane (Argania spinosa) on fattening performance, carcass characteristics and fatty acid composition of lambs

The current study was performed in order to evaluate the effect of using argane by-products (oil cake and pulp) as fattening diet of lambs. This was achieved through an experimental lamb fattening investigation using argan by-product as feeding source and the exploration of the fattened lamb performance, carcass characteristics and the chemical fatty acid composition of the quality produced meat. Twenty fattening Sardi lambs (26 ± 0.5 kg body weight and six months old) were divided into two (n = 10) homogenous experimental and control groups. Argane by-products (ABP) and traditional (CF) diets have been used for feeding the experimental and control groups respectively during a period of 75 days. The results obtained for both groups were used to determine the effect of feeding argane by-products on animal weight, average daily gain (ADG), carcass weight, muscle pH values, dressing %, dry matter, ash, ether extract, crude fiber, crude protein, and fatty acid composition. The obtained results showed that the experimental ABP group lambs had higher average daily gain and meat chemical, crude protein and ash and proportion of C18:0 than the control CF group lambs, while the control CF group had a higher feed conversion ratio, ether extract, mesenteric and perirenal fat. The results obtained for pH0 and pH24 were similar for both explored groups. The obtained results showed thus that the use of ABP as a diet to fattening lambs increased their performance and lean meat yield.

The Effects of Production System and Sex on the Sensory Quality Characteristics of Dorper Lamb

The effect of production systems on the sensory quality characteristics of Dorper lambs was investigated. Sixty lambs (ewes, rams, castrates) were allocated into two production groups (feedlot or free-range) at weaning with equal numbers of each sex represented in each group. The lambs were fed for five (slaughter group 1) or six (slaughter group 2) weeks. Feedlot lambs were fed a commercial pelleted diet while free-range lambs utilized natural shrub pastures. Samples of the Longissimus thoracis muscle were used for sensory evaluation. Feedlot lambs produced meat that was juicier and more tender than meat from free-range lambs. Initial juiciness was also higher in the meat from the feedlot lambs. No aroma or flavour differences were observed. The meat from the free-range ram lambs (slaughter group 1) was the least tender, whereas the lamb flavour was also compromised in the free-range ram lambs. Free-range meat may not necessarily be distinguished from feedlot meat as far as aroma and flavour are concerned.

The Effect of Production System and Finish Weight on Carcass and Meat Quality of Kivircik Lambs

Fifty-two male Kivircik lambs were used to investigate the influences of finish weight (LOW: 25–26 kg, MEDIUM: 30–31 kg and HIGH: 35–36 kg) and production system (CON: concentrate-based system, PAS: pasture-based system) on carcass and meat quality characteristics. CON lambs (n=27) were weaned at 76 d of age and then finished on concentrate feed and alfalfa hay until slaughter. PAS lambs (n=25) grazed on native pasture in the day-time and sucked their dams until slaughter. CON group grew 30% faster during the experimental period; therefore significantly fewer days were required to reach the target weight. CON lambs had higher cold carcass weight, cold dressing percentage, and produced fattier carcasses compared with those of PAS system. PAS lambs had lower meat lightness values than CON ones. CON system produced more tender meat than PAS system in terms of shear force and sensory evaluation results. Intramuscular fat of the PAS lambs had higher percentage of ∑PUFA and ∑n-3 PUFA, and lower n-6/n-3 ratio than that of CON ones. Finish weight had no influence on dressing percentage and carcass fatness. Meat of HIGH lambs had lower L* value than other groups. Panellists gave lower scores to meat of MEDIUM lambs for tenderness when compared with other groups. In conclusion, CON system might be considered to obtain higher carcass dressing, lighter meat colour and more tender meat, while PAS system had an advantage of lower n-6/n-3 ratio and of higher ∑n-3 PUFA percentage. PAS lambs had lower fatness level than CON ones. Therefore, if priority is given to fatty acid composition and carcass with lower fat, PAS system might be considered. Finish weight of 35–36 kg might be preferred to increase lamb production, without any adverse effect on carcass and meat quality in both of the production systems.

Main Factors Affecting Animal Welfare and Meat Quality in Lambs for Slaughter in Chile

Consumers have become increasingly demanding about the quality of products of animal origin, particularly regarding animal welfare during production, transport, and slaughter. The aim of the present study was to review the factors affecting the welfare of lambs for slaughter in Chile and show the implications on meat quality. Rounding up and driving the lambs from the fields in large extensive production systems and long distance transport through difficult geographical routes affect the blood variable indicators of stress and reduces muscle glycogen reserves, increasing the risk of high pH of meat. In small farmer sheep production conditions there is a lack of appropriate installations for loading/unloading and deficiencies in vehicle structure specific for lambs; this together with the work of untrained handlers results in a high percentage of mortality and bruised carcasses, compared to European studies. These problems are common for other South American countries and should be addressed firstly by educating and training all the people involved in the lamb meat chain regarding animal welfare. In Chile there is legislation, ongoing since 2013, regarding the protection of animals during production, transport, and slaughter, including compulsory training of animal handlers and livestock transporters, which should improve animal welfare and meat quality.

The Effect of Extensive Feeding Systems on Growth Rate, Carcass Traits, and Meat Quality of Finishing Lambs

This review aims to summarize the relevant published information about the effects of extensive feeding systems on the carcass and meat quality characteristics of lambs. Lambs finished in a feedlot or with supplementation under extensive systems exhibit faster growth rates, achieve target weights quicker, and produce heavier carcass weights when compared to grazing lambs. However, the literature also shows that finishing lambs on high-quality pasture can produce satisfactory growth rates without compromising carcass and meat quality traits. Lately, the consumer demand for products perceived as "healthy" and that are produced where animal welfare is optimal under systems which do not impact negatively on the environment, has heightened the interest in lamb production under extensive systems. Lambs raised on pasture can meet many of these specifications. Also, lambs fed higher quality green pasture can produce meat with greater amounts of health-claimable omega-3 fatty acids such as eicosapentaenoic acid plus docosahexaenoic acid than feeding systems based on feedlot pellets, grain, or dry pasture/straw. It is apparent that in some previous published research, the number of animals allocated for each treatment, and the lack of replicates, makes it difficult to formulate a correct understanding of the effect of forages on lamb carcass and meat quality. Future research should concentrate on the effect of legume, improved pasture, and specialized forage finishing systems on growth rate, carcass traits, and nutritional value of meat using well-designed experiments with an adequate number of lambs and appropriate paddock replicates per treatment.

Efficient halal bleeding, animal handling, and welfare: A holistic approach for meat quality

Traditional halal slaughter and other forms of religious slaughter are still an issue of debate. Opposing arguments related to pre-slaughter handling, stress and pain associated with restraint, whether the incision is painful or not, and the onset of unconsciousness have been put forward, but no consensus has been achieved. There is a need to strike a balance between halal bleeding in the light of science and animal welfare. There is a paucity of scientific data with respect to animal welfare, particularly the use of restraining devices, animal handling, and efficient halal bleeding. However, this review found that competent handling of animals, proper use of restraining devices, and the efficient bleeding process that follows halal slaughter maintains meat eating quality. In conclusion, halal bleeding, when carried out in accordance with recommended animal welfare procedures, will not only maintain the quality and wholesomeness of meat but could also potentially reduce suffering and pain. Maintained meat quality increases consumer satisfaction and food safety.

The effect of forage type on lamb carcass traits, meat quality and sensory traits

The aim of this study was to evaluate the effect of different forage-types on lamb carcass, meat quality and sensory attributes. Sixty-two, White Dorper lambs finished on bladder clover, brassica, chicory+arrowleaf clover, lucerne+phalaris or lucerne, were slaughtered at a commercial abattoir. At 24h post-mortem, the m. longissimus thoracis et lumborum (LL) was removed from the left side and sliced into three equal sub-samples, vacuum packaged and randomly assigned to ageing periods (5, 12 or 40days) and the right side was aged for 5days. The m. semimembranosus and m. adductor femoris were removed and, the former was then aged for 40days. Lambs fed chicory+arrowleaf clover or lucerne had a higher dressing percentage and fat depth. Bladder clover gave the highest level of glycogen in the LL. No sensory or other meat quality trait differences were found between the treatments. In general, no treatments showed any unfavourable effect on the traits examined.

Glycolytic potential and activity of adenosine monophosphate kinase (AMPK), glycogen phosphorylase (GP) and glycogen debranching enzyme (GDE) in steer carcasses with normal (<5.8) or high (>5.9) 24h pH determined in M. longissimus dorsi

Muscle glycogen concentration (MGC) and lactate (LA), activity of glycogen debranching enzyme (GDE), glycogen phosphorylase (GP) and adenosine monophosphate kinase (AMPK) were determined at 0.5h (T0) and 24h (T24) post-mortem in Longissimus dorsi samples from 38 steers that produced high pH (>5.9) and normal pH (<5.8) carcasses at 24h postmortem. MGC, LA and glycolytic potential were higher (P<0.05) in normal pH carcasses. GDE activity was similar (P>0.05) in both pH categories. GP activity increased between T0 and T24 only in normal pH carcasses. AMPK activity was four times higher in normal pH v/s high pH carcasses, without changing its activity over time. Results reinforce the idea that differences in postmortem glycogenolytic/glycolytic flow in L. dorsi of steers showing normal v/s high muscle pH at 24h, could be explained not only by the higher initial MGC in normal pH carcasses, but also by a high and sustained activity of AMPK and an increased GP activity at 24h postmortem.

Effect of production system on carcass measurements and meat quality of Kivircik lambs

Effect of production system on carcass and meat quality was investigated in four groups of lambs: i. W-C lambs were weaned between 45 and 60 days of age and then were fattened with concentrate feed until slaughter; ii. W-G-S lambs were weaned and then taken to pasture and wheat stubble; iii. UW-C lambs were fattened with concentrate feed and they suckled their dams until slaughter; iv. UW-G lambs were kept with their dams and were taken to pasture in the day-time. Hot carcass weight was 13.62, 12.52, 14.37 and 13.88 kg (P < 0.001), and dressing percentage was 55.24, 51.77, 57.83 and 55.38% (P < 0.001), for W-C, W-G-S, UW-C and UW-G lambs, respectively. Ultimate meat pH was higher in W-G-S lambs than lambs from W-C and UW-C systems (P < 0.05). W-G-S lambs had higher shear force value in longissimus dorsi muscle (P < 0.05) and lower meat lightness (P < 0.001) than those of other systems. Panellists gave the lowest sensory scores, except juiciness, to meat of W-G-S lambs.

Sire and growth path effects on sheep meat production. 2. Meat and eating quality

The meat and eating quality characteristics of 627 crossbred lamb progeny from 20 Poll Dorset sires were studied. The sires were selected on the basis of Australian sheep breeding values (ASBVs) for postweaning growth (PWWT), depth of loin muscle (PEMD) and subcutaneous fat (PFAT). Lambs were either weaned at 20- or 30-kg liveweight and then within each of these groups held at their weaning weight for 55 days or fully fed, giving four treatment groups. Restricted lambs were realimentated subsequent to the period of feed restriction and the lambs within each treatment group were slaughtered when their mean liveweight reached 45 kg.Shear force of the M. longissimus thoracis et lumborum (LL) decreased with temperature at pH 6.0, increased with LL ultimate pH and decreased as sarcomere length increased. Within LL aged for 5 days there was no difference between (P > 0.05) between treatments for shear force. There was a treatment effect on M. semimembranosus (SM) shear force, such that for a sire having an average ASBV PWWT of 9.34, topsides from lambs early weaned and restricted had significantly (P < 0.05) lower values. Further within these same lambs, i.e. early weaned and restricted, as the sire ASBV PWWT increased there was a significant (P < 0.001) reduction in shear force. There was a significant (P < 0.05) increase in sensory tenderness as the sire ASBV PFAT increased and across the range of ASBV PFAT this represented a change in sensory tenderness of four points. Overall liking increased with an increase in the temperature at pH 6.0 (P < 0.05) with a coefficient of 0.43 ± 0.19. There was a significant (P < 0.05) interaction between feeding level and the sire ASBV PFAT, such that for restricted fed lambs overall liking increased as the ASBV PFAT increased (coefficient 2.80 ± 0.89) after adjusting for temperature at pH 6.0, but this is not the case for fully feed lambs (coefficient –0.01 ± 0.89). Subtle interactions between sire ASBVs and growth path suggest that the impact of a period of restriction and refeeding on meat and eating quality will be meditated by the sire genetics.

Relationship between sire estimated breeding values and the meat and eating quality of meat from their progeny grown on two planes of nutrition

The meat of 140 female lambs was examined. These lambs were sired by 9 Poll Dorset sires (3 selected for growth, 3 for muscling and 3 control) and fed either a low or high plane of nutrition from birth to slaughter. All carcasses were electrically stimulated and portions of M. longissimus thoracis et lumborum (loin) aged for 5 days before freezing. Subsequently, 10 consumers tested each portion for eating quality traits. A portion of the same muscle from the opposing side of the carcass was divided into 3 sections and aged for either 1, 3 or 5 days and then used to measure shear force (objective tenderness). Portions of the M. semimembranosus (topside) were also aged for 3 or 5 days and subjected to shear testing. Low plane animals produced tougher loins (based on shear force). As ultimate pH increased, shear force of the loin increased for low plane animals, while for high plane animals there was no such effect. This latter group had significantly lower ultimate pH values in all 3 muscles tested. Plane of nutrition had the greatest effect on topside shear force with low plane lambs producing tougher topsides. As ultimate pH increased, the topsides became tougher and as expected ageing improved the tenderness. There was no effect of sire EBVs (estimated breeding values) on shear force or objective meat quality traits apart from loin lightness which increased as the EBV for post-weaning weight (PWWT) increased and intramuscular fat in the loin which decreased as sire EBV for post-weaning muscle depth (PEMD) increased. Plane of nutrition did not have a significant effect on eating quality attributes as assessed by consumers. There was, however, an effect of sire EBV for muscling (PEMD) on tenderness, juiciness, flavour and overall liking, such that increased EBV led to decreased scores for the sensory traits. The findings suggest selection of sires for increasing PEMD will have a detrimental affect on the eating quality of their progeny, but this will not be reflected in shear force values or other objective meat quality traits apart from intramuscular fat. The effects of a low plane of nutrition on eating quality were minimal and largely controlled by the use of best practice processing, but were evident for a number of meat quality traits.