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This paper reports relationships between fatty acids (FAs) and intramuscular fat (IMF)% in M. longissimus lumborum samples from 108 pasture-fed ewe lambs. Samples ranged in IMF from 1 to 6%. Relationships between %FA with total IMF% were mainly linear with percentages of saturated and monounsaturated FAs (MUFA), including trans-FAs, increasing and polyunsaturated FAs decreasing as IMF% increased. Normalized FA content data at 5.5% relative to 1.5% IMF, showed the highest relative increase for C14:0 as rates of endogenous synthesis increase with higher IMF deposition. This can be related to enhanced C12:0 elongation and lower rates of C14:0 desaturation, supported by a preferential desaturation of C18:1 trans-11 and C18:0 compared with C14:0 and C16:0 as IMF increased. The greatest normalized increase after C14:0 was anteisoC17:0 followed by other branched chain FAs and then trans-MUFA and C18:2 cis-9,trans-11. Finally, C22:6 and C22:5 showed higher relative increase than C20:5 indicating greater rates of elongation and desaturation past C20:5 at higher levels of fatness., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Samples of pork longissimus muscle (n=16) cooked to either 60°C or 75°C in a water bath for 90 min were assessed for amino acid composition. Recovery of protein in the cooked meat plus the cooking juice was >93% and was slightly higher at 60°C (P=0.031), but retention in the meat was only 89% and 82% for the lower and higher temperatures (P<0.0001). Individual amino acids varied in recovery and retention with retention being particularly low for taurine and histidine. The balance of indispensable amino acids was less than ideal, with leucine and valine being the limiting amino acids by about 30% for both raw and cooked pork. Cooking had no detrimental effect on amino acid balance. Some examples of small effects of genotype and sex on amino acid composition of pork were shown., (© 2013.)

The aim of the present study was to produce pork with enhanced nutritive value for humans, both in terms of fatty acid profile (mainly long chain n-3 fatty acids by feeding fish oil) and selenium. Forty-eight female pigs were allocated to one of six treatment groups: animal by-products and plant feedstuffs with tallow, plant feedstuffs with a blend of soybean oil and linseed oil with or without a supplement (CLA, selenium, vitamin E and vitamin C), plant feedstuffs with tallow and supplement, plant feedstuffs with fish oil and supplement. The diets containing the fish oil were fed up to either 49 days or 28 days before slaughter. The dietary treatments had no significant effects on growth performance, carcass characteristics and meat quality. When fish oil was included in the diet, higher levels of EPA, DPA and DHA were measured in the subcutaneous fat (up to 3.74%)., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The current EUROP beef carcass classification scheme is still largely dependent on visually assessed fatness and conformation and its purpose is to provide a common basis for the description of carcasses for use in trade, price reporting and intervention. The meat industry, however, aims for accurately predicted saleable meat yield (SMY%) to which the EUROP carcass classification shows highly variable correlations due in part to the variable distribution of fat throughout the carcass as affected by breed, sex, diet, and the level of fat trimming. Video image analysis (VIA) technology is capable of improving the precision and accuracy of SMY% prediction even for specific carcass joints and simultaneously mimics the visual assessment to comply with EU regulations on carcass classification. This review summarises the development and use of VIA for evaluation of beef carcasses and discusses the advantages and shortfalls of the technology and its application., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Norwegian reindeer of Finnmark county live under harsh conditions on extensive feed sources. Thus the meat may have special qualities. M. longissimus lumborum from 30 animals was investigated with respect to carcass and meat quality and compositional/nutritional characteristics. Meat from calves had a higher myofibrillar fragmentation index and tenderness, and had lighter, redder and more yellow colour than meat from adult reindeer. Regarding nutritional compounds the meat from calves had lower antioxidant capacity, and higher taurine levels than adults, while the levels of iron, carnosine, anserine, and vitamin E were similar. Carcass weights of the adult reindeer were lower than the weights reported for Swedish reindeer and New Zealand farmed red deer. Reindeer muscles had higher antioxidant capacity, shorter sarcomeres, smaller muscle fibre diameters, higher n-6/n-3 ratios of fatty acids in the intramuscular fat and higher muscle taurine levels relative to values for the same muscle of New Zealand farmed red deer., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The results reported here showed that threshold concentrations of skatole and indole in rice-bran oil for Singaporean consumers were 0.028 μg/g and 0.051 μg/g, respectively, and that skatole and indole levels in subcutaneous fat of pigs can be affected by diet. In Experiment A, 31 female pigs were fed with diets based on plant products only (P) or plant plus animal by-products (AP), with added levels of garlic essential oil from zero to 2.15 g/kg feed. Concentrations of skatole and indole increased with increasing garlic concentration (P < 0.001). In Experiment B, P and AP diets were fed to 47 female pigs with different dietary lipid sources (fish oil, tallow, and a mix of linseed oil and soya oil). Skatole and indole concentrations were higher in backfat of pigs fed with the AP diet (P < 0.05), but were unaffected by the type of lipid., (Copyright © 2010 The American Meat Science Association. Published by Elsevier Ltd. All rights reserved.)

Meat quality and composition characteristics are reported for the longissimus muscle from 10 red deer stags and 10 hinds aged about 20 months. All animals were pasture-finished but the stags and hinds came from different farms. The average carcass weight was 3.4 kg greater for the stag group (55.8 vs 52.4 kg; P=0.04), but measures of GR as a measure of fatness were similar and intramuscular fat content was significantly greater for the hind group (1.12% vs 0.63%; P<0.0001), as expected. The tenderness of cooked venison in terms of shear force and compression measures was significantly better for venison from the hind group, possibly due to the greater amount of intramuscular fat and slightly longer sarcomeres. The gender groups did not differ in absolute measures of colour or in the rate at which it deteriorated on display. However, the rate of colour deterioration was more rapid than other meats such as beef, as has been demonstrated elsewhere. The average ultimate pH and water-holding capacity were similar for the two groups. Venison from hinds contained more coenzyme Q(10), taurine, anserine, carnosine, and vitamin E. Group differences in fatty acid composition of intramuscular fat appeared to be mainly due to levels of fatness, which was greater for the hind group., (Copyright (c) 2010 The American Meat Science Association. Published by Elsevier Ltd. All rights reserved.)

Garlic essential oil (GEO) added directly to pork mince or to the diet of pigs was evaluated for its effectiveness in masking undesirable mutton flavour. Pork was from 31 female pigs (Duroc x (Large White x Landrace)) grown on diets containing either animal-plus-plant products (AP diet) or plant products only (P diet) with four levels of GEO: 0, 0.55, 1.44 and 1.84 g/kg feed and 0, 0.55, 1.44 and 2.15 g/kg feed in the AP and P diet, respectively. Garlic flavour increased and mutton flavour decreased in pork from pigs that consumed more than about 150 g and 220 g of GEO in P and AP diets, respectively over the 57-day feeding period. The garlic flavour was stronger and the mutton flavour less intense for pork from pigs on the P diet. When GEO was added to pork mince at 125 ppm, it significantly reduced mutton flavour., (2009 Elsevier Ltd. All rights reserved.)

A range of composition characteristics of the longissimus (LL) and semimembranosus (SM) muscles were compared between pigs raised in intensive and extensive production systems in New Zealand (NZ), and pigs raised in an intensive system in Indonesia for supply to the Singapore market (n=8/group). Ultimate pH was slightly higher for the Singaporean LL muscles (P<0.05), while LL muscle of the NZ extensive group was redder (higher a(∗) values) and contained more fat (P<0.05). Muscle iron levels were highest for the NZ extensive group and lowest for a lighter group within the Singapore pigs (P<0.05). Differences in fatty acid concentrations, which were also measured in a sample of the belly cut, could largely be attributed to the effects of diet, with higher levels of alpha linolenic acid for the NZ extensive group (P<0.05) due to linseed in the diet, and much higher levels of linoleic acid and the P:S ratio for the Singapore group (P<0.05). Some statistically significant differences in amino acid concentrations were shown between muscles and groups, but they were not large. With respect to compounds with potential bioactive properties, coenzyme Q10, and taurine levels were higher in pork from NZ pigs, and carnosine levels were highest for the NZ intensive group (P<0.05). The LL muscle contained more coenzyme Q10 and taurine, but less carnosine than the SM muscle (P<0.001). It is concluded that some of these composition differences in the pork from the muscles and groups compared may be of commercial importance, but several are likely to have been due to dietary or weight differences.

The dromedary camel is a good source of meat especially in areas where the climate adversely affects the performance of other meat animals. This is because of its unique physiological characteristics, including a great tolerance to high temperatures, solar radiation, water scarcity, rough topography and poor vegetation. The average birth weight of camels is about 35kg, but it varies widely between regions, breeds and within the same breed. The meat producing ability of camels is limited by modest growth rates (500g/day). However, camels are mostly produced under traditional extensive systems on poor levels of nutrition and are mostly slaughtered at older ages after a career in work, racing or milk production. Camels reach live weights of about 650kg at 7-8 years of age, and produce carcass weights ranging from 125 to 400kg with dressing-out percentage values from 55% to 70%. Camel carcasses contain about 57% muscle, 26% bone and 17% fat with fore halves (cranial to rib 13) significantly heavier than the hind halves. Camel lean meat contains about 78% water, 19% protein, 3% fat, and 1.2% ash with a small amount of intramuscular fat, which renders it a healthy food for humans. Camel meat has been described as raspberry red to dark brown in colour and the fat of the camel meat is white. Camel meat is similar in taste and texture to beef. The amino acid and mineral contents of camel meat are often higher than beef, probably due to lower intramuscular fat levels. Recently, camel meat has been processed into burgers, patties, sausages and shawarma to add value. Future research efforts need to focus on exploiting the potential of the camel as a source of meat through multidisplinary research into efficient production systems, and improved meat technology and marketing.

Samples of longissimus (LT) and infraspinatus (IS) muscles from five contrasting groups of pasture-finished cattle (n=7/group) were assessed for quality and composition characteristics in order to determine whether features of pasture-finished beef reported previously apply across different muscles and different classes of cattle. The cattle were not raised together or slaughtered at the same time. Wagyu-cross steers had the highest intramuscular fat levels, particularly in the LT, followed by Angus steers, Charolais-cross steers and Belgian Blue-cross steers, with the lowest levels for Friesian bulls. Relative to the LT, the IS muscle had longer sarcomeres, higher cooking losses, higher concentrations of vitamin E, and lower myofibrillar fragmentation indexes, while its ultimate pH was slightly higher but less variable. Beef from Wagyu-cross steers had the highest chroma values and the lowest shear values, while Friesian bull beef was darkest and least tender. Intramuscular fatty acid composition and concentrations of bioactive compounds such as coenzyme Q(10) and carnosine, were similar to those reported previously for cattle finished on New Zealand pastures although taurine levels were lower. Generally concentrations of bioactive compounds differed more between muscles and groups than between cattle finished on pasture or grain as reported previously.

Pork from the LM and semimembranosus muscle (SM) of 59 female Duroc-cross pigs with a mean carcass weight of 80.1 kg (SD = 3.2) were assessed for quality. The pigs were grown on diets containing either animal and plant products (the animal group) or plant products only (the plant group), with or without a supplement (0.31% of the diet) containing extra CLA, selenium, and vitamin E. The 45-min postmortem pH of LM was unaffected by dietary treatment (mean 6.44, SD = 0.21), but the ultimate pH (pHu) was lower for the supplemented animal group for both muscles within the animal group (P < 0.04). Water-holding capacity in terms of drip loss for SM and expressed juice levels for LM, but not cooking loss, was also lower for the supplemented animal group (P < 0.01), but this difference was reduced after adjustment to a constant pHu (P < 0.07). Warner-Bratzler shear force (WBSF) values were greater for the plant group for LM only (P < 0.05), both before and after pHu adjustment. Differences between dietary treatment groups for color (L*, a*, and b*) were small and seldom significant before or after pHu adjustment. Sensory assessment of LM samples (with 5% subcutaneous fat added) from 32 pigs (8 per group) for 8 odor notes and 11 flavor notes by a trained analytical sensory panel of 13 people revealed no differences between the groups, except that the percentage of instances in which a rancid odor was detected was greater for the supplemented plant group compared with the control plant group (25 vs. 12%). Differences (P < 0.001) were shown between the muscles such that, relative to SM, LM had lower pHu values, greater drip losses, greater WBSF values, greater L* values, and lower chroma values, but similar levels of cooking loss. It is concluded that the dietary treatments imposed to improve the nutritional value of pork had some effects on certain meat quality parameters, but that the overall effects on appearance and palatability were small and unlikely to be of practical importance.

The objective of this study was to evaluate the effect of dietary manipulations on the fatty acid composition, Se content, and vitamin E content of pork. Sixty Duroc-cross gilts were randomly allocated at weaning to 1 of 4 dietary treatment groups (n = 15 per group). The 4 experimental diets were based on animal plus plant components or plant components only, with or without the inclusion of a dietary supplement (0.614%) containing CLA, Se, and vitamin E. The growth performance to approximately 100 kg of BW was similar with diets containing animal plus plant components or only plant components. Growth was also similar when either of these diets included the supplement. Inclusion of the supplement led to expected increases in Se and vitamin E contents (P < 0.001) of the LM. The differences found in the fatty acid profile of the lipid in LM, loin subcutaneous fat, and the belly cut (pork belly) between the groups with and without animal components in their diets largely reflected differences in the diet composition. Inclusion of the supplement led to greater CLA contents in all 3 tissues (P < 0.001), and also to lower contents of oleic acid (P < 0.001) and greater contents of stearic acid (P < 0.05), possibly due to an inhibition of stearoyl-CoA desaturase enzyme. The supplement also led to an increase in LM intramuscular fat (P < 0.05), but did not affect P2 fat depths (65 mm lateral to the midline of the spine at the last rib; mean depth of 11.8 mm). It is concluded that changing from a part animal component diet to an all plant diet will not change the growth performance of pigs but changes in the fatty acid profile of pork are likely to occur. It is further concluded that the nutritional value of pork may be successfully enhanced by simultaneously supplementing the diet with CLA, selenium, and vitamin E.

Since the tissue characteristics of monogastric species are readily influenced by the composition of the feeds they consume, the objectives of this preliminary study were to assess the performance of finisher pigs on diets containing 0.05% of essential oils or oleoresins of rosemary, garlic, oregano, or ginger, and to determine the effect of these diets on pork quality. The pigs preferred the garlic-treated diet, and feed intake and average daily gain were significantly increased although no difference in feed efficiency was observed. Carcass and meat quality attributes were unchanged by dietary treatment, although a tendency towards reduction of lipid oxidation was noted in oregano-fed pork. Sensory panelists were unable to detect a flavour/aroma difference between treated and control pork. These results indicate that a higher level of dietary supplementation may be required in order to effect observable differences in pork characteristics.

Longissimus muscle samples from 31 Angus-cross heifers finished on either a high-concentrate feedlot diet or pasture were used to evaluate the effects of cooking (71°C) on the concentration and forms of iron in the meat, and also on concentrations of the bioactive compounds taurine, carnosine, coenzyme Q(10), creatine and creatinine. For a sub-sample of 15 the effects of pepsin and pancreatin digestion were assessed. For iron, cooking resulted in some overall loss together with a major change from soluble haem and non-haem iron to the insoluble forms, but solubility was regained to a significant extent following digestion. Total haem iron percentage, however, decreased at each step from an initial 88% to a final 61% of total iron. For the bioactive compounds, cooking led to a reduction in taurine, carnosine, coenzyme Q(10), and creatine. The effects of digestion on the bioactive compounds varied. No clear differences were shown in the way in which beef from pasture-finished and feedlot-finished cattle responded to cooking and digestion.

Modified atmosphere packaging with carbon dioxide is effective for prolonging shelf-life of fresh meat. Addition of carbon monoxide to the system provides the advantage of enhancing meat colour. The study objective was to determine the effect of CO(2)-MAP+0.4% CO, vs. 100% CO(2)-MAP, on the bacteriology and colour of retail-ready fresh pork stored for 8 weeks in a master-package system. Total plate counts were not affected and listeria was present on meat from both treatments. Colour was enhanced with the inclusion of CO, while no effect on lipid oxidation was observed. Use of CO in MAP provides sufficient storage life and product colour quality to permit shipment of fresh pork to distant markets. However, given the stable fresh colour of CO-treated meat and the lack of inhibition of pathogen growth by CO, there is concern that CO-MAP under certain conditions may pose a food safety risk.

A QTL affecting leg muscle and fat traits has been identified within the New Zealand Texel population. The QTL maps to a region on OAR 2 with a two-marker haplotype test established at markers BULGE20 and BM81124. These markers encompass the likely position of Growth Differentiation Factor 8 (GDF8). The pleiotropic effects of this QTL on meat quality traits are tested. Objective measures of meat quality including pH, color (L*, a*, and b*), and tenderness (as assessed by Warner-Bratzler shear force measurements) were assessed on longissimus and semi-membranosus muscles of 540 progeny from six Texel sires. Four of these sires were subsequently identified as segregating for leg muscle and fat traits. For these segregating sires, comparison of progeny that had inherited the favorable haplotype from their sire with those that had received the alternate haplotype revealed no significant differences in the meat quality traits assessed. This finding suggests that the muscling QTL does not have pleiotropic effects on meat quality. A general scan for meat quality QTL was carried out using genotype data for eight markers from FCB128 to RM356 flanking 122cM of OAR 2 using Haley-Knott regression. This analysis revealed two QTL for a single sire. A QTL detected in the region of Marker INRA40 for color L* mapped to a site close to the muscling QTL, but there was evidence to suggest it is at a distinct locus. The QTL in the region of Marker RM356 might map distal to Marker RM356, as no peak was observed. This QTL, which seems to affect pH, color a*, color b*, and Warner-Bratzler shear measurements, requires further characterization.

Comparisons were made of carcass and meat quality characteristics of pasture-raised Texel-cross ewe (n=269) and ram (n=275) lambs between 5 and 8 months of age with an average carcass weight of 17.2kg. Carcass assessment was based on linear dimensions and dissection of a leg into muscle, fat and bone, and meat quality measurements were made on M. semimembranosus and M. longissimus. At a set carcass weight, ewe lambs had higher dressing percentages (2%), shorter carcasses (0.7cm), and heavier leg cuts (35g) (P<0.01) than males. At the same leg weight, legs of ewe lambs were fatter than males (subcutaneous plus intermuscular fat; 11.2% vs 9.6%; P<0.001), whereas legs of ram lambs contained significantly more muscle and bone than females (P<0.001). Leg muscle to bone ratio (4.7 vs 4.4) and muscularity were higher for females than males (P<0.001). However, the relationship between leg muscle to bone ratio and muscularity was not the same between the sexes, and for any given muscularity value the muscle to bone ratio of ram lambs was lower than females. As a result, if carcass lean meat yield is predicted from a measure of carcass shape, such as muscularity, lean meat yields will be overestimated for males and underestimated for females. Meat quality was lower in ram lambs than in females (P<0.001) as shown by higher Warner-Bratzler shear values (peak value 109.8 vs 97.0N for M. Semimembranosus), higher ultimate meat pH values, and lower redness (a(∗)) and lightness (L(∗), for the longissimus muscle only) values (P<0.001). It is concluded that significant differences between ewe and ram lambs do exist for many carcass and meat quality traits, but for most quality traits the differences are small.

A directed search for QTL affecting carcass traits was carried out in the region of growth differentiation factor 8 (GDF8, also known as myostatin) on ovine chromosome 2 in seven Texel-sired half-sib families totaling 927 progeny. Weights were recorded at birth, weaning, ultrasound scanning, and slaughter. Ultrasonic measures of LM cross-sectional dimensions and s.c. fat above the LM were made, with the same measurements made on the LM after slaughter. Following slaughter, linear measurements of carcass length and width were made on all carcasses, and legs and loins from 540 lambs were dissected. Genotyping was carried out using eight microsatellite markers from FCB128 to RM356 on OAR 2 and analyzed using Haley-Knott regression. There was no evidence for QTL for growth rates or linear carcass traits. There was some evidence for QTL affecting LM dimensions segregating in some sire families, although it was not consistent between ultrasound and carcass measures of the same traits. There was strong and consistent evidence for a QTL affecting muscle and fat traits in the leg that mapped between markers BM81124 and BULGE20 for the four sires that were heterozygous in this region, but not for the three sires that were homozygous. The size of the effect varied across the four sires, ranging from 0.5 to 0.9 of an adjusted SD for weight-adjusted leg muscle traits, and ranging from 0.6 to 1.2 of an adjusted SD for weight-adjusted leg fat traits. The clearest effect shown was for multivariate analysis combining all leg muscle and fat traits analyzed across sires, where the -log(10) probability was 14. Animals carrying the favorable haplotype had 3.3% more muscle and 9.9% less fat in the leg relative to animals carrying other haplotypes. There was evidence for a second peak in the region of marker TEXAN2 for one sire group. It seems that a QTL affecting muscle and fat traits exists within the New Zealand Texel population, and it maps to the region of GDF8 on OAR2.

Samples of longissimus (LL) and triceps brachii (TB) muscles from Angus-cross heifers finished either on a high-concentrate ration in Washington, USA, (US cattle, n=15) or on pasture in New Zealand (NZ cattle, n=16) were assessed for composition characteristics. Half of the NZ cattle were of a similar age to the US cattle (NZAge) and half were of a similar weight (NZWt). Iron concentration was higher in TB (20.9 vs. 17.5μgg(-1); P<0.001) and was higher for the NZWt group than the NZAge group or the US cattle. The proportion of iron as haem iron was highest for the NZWt group (87.3%; P<0.01), but the proportion as soluble haem iron was highest for the US cattle. For a sub-group of 10 pasture-finished cattle, iron levels in cheek muscle were higher than for LL or TB, and liver levels were 66% higher than cheek muscle. The proportion of haem iron, however, was lowest in liver (55.3%) and was lower in cheek muscle (78.4%) than LL or TB. Relative to LL, TB had higher levels of taurine and coenzyme Q(10), but lower levels of carnosine, creatine and creatinine, as expected for a muscle with a more aerobic metabolism. These differences were magnified for the even more aerobic cheek muscle. Differences between the two NZ groups were small, but muscles from the US cattle contained less taurine, carnosine, coenzyme Q(10), and creatinine. Reasons for these differences in various meat components for similar cattle from different production systems are not clear.

The concentrations of fatty acids were measured in intramuscular fat from the longissimus lumborum (LL) and triceps brachii (TB) muscles of Angus-cross heifers finished either on a high-concentrate ration in Washington, USA, (US cattle, n=15) or on pasture in New Zealand (NZ cattle, n=16). Half of the NZ cattle were of a similar age to the US cattle (NZAge) and half were of a similar weight (NZWt). Intramuscular fat levels were higher for the LL muscle and for the US cattle but only within the LL muscle (P<0.05). Aspects of the fatty-acid patterns that are of relevance to human nutrition tended to favour the pasture-finished NZ cattle with lower n-6/n-3 fatty acid ratios (P<0.001), higher concentrations of an anticarcinogenic conjugated linoleic acid (C18:2 c9,t11) (P<0.05) and its precursor (trans-vaccenic acid, TVA) (P<0.01), and lower levels of the 18-carbon trans monounsaturated fatty acids other than TVA (P<0.01). Concentrations of 20 of the 22 fatty acids analysed differed significantly between the two muscles. When values were adjusted to a common intramuscular fat level by covariance, most of the group differences remained, but a number of the muscle differences became non-significant. For almost half the fatty acids considered, there was a significant interaction between treatment group and muscle, which indicates that the results for one muscle do not necessarily apply to other muscles, although the ranking of the groups was usually the same for both muscles.

The influence of final cooked temperature on the form of iron present and on the concentration of taurine, carnosine, coenzyme Q(10) and creatine was investigated in surface and inner parts of 30-mm thick steaks from beef semitendinosus muscle (n=6). The use of a fast, dry-heat cooking method with a Silex clam cooker (set at 200 °C) led to cooking times ranging from 5.6 to 8.6 min for final internal temperatures of 60 and 85 °C, respectively. The proportion of iron as soluble haem iron decreased from 65% in uncooked meat to 22% when cooked to 60 °C and then decreased more gradually with increases in final cooked temperature. The proportion of insoluble haem iron increased in a reciprocal manner, while changes in the proportions of soluble and insoluble non-haem iron were relatively small, but increases in the percentage of insoluble non-haem iron with increasing final temperature were significant (P<0.01). Changes in the forms of iron with cooking generally took place more rapidly in surface samples than inner samples. On a dry-matter basis, concentrations of taurine, carnosine, coenzyme Q(10), and creatine all decreased with cooking, but the decreases were greatest for taurine and creatine. Losses of creatine were at least partly due to conversion to creatinine, and, along with the other compounds, probably included some loss in cooking juices. It is concluded that despite these changes with cooking, beef semitendinosus muscle remains a good source of iron and a useful source of the potentially bioactive compounds taurine, carnosine, coenzyme Q(10) and creatine.

Levels of taurine, carnosine, coenzyme Q(10), and creatine were measured in beef liver and several muscles of beef and lamb and in cooked and uncooked meat. The amino acid taurine has numerous biological functions, the dipeptide carnosine is a buffer as well as an antioxidant, coenzyme Q(10) is also an antioxidant present within mitochondria, and creatine along with creatine phosphate is involved with energy metabolism in muscle. Large differences were shown for all compounds between beef cheek muscle (predominantly red fibres) and beef semitendinosus muscle (mainly white fibres), with cheek muscle containing 9.9 times as much taurine, and 3.2 times as much coenzyme Q(10), but only 65% as much creatine and 9% as much carnosine. Levels in lamb relative to beef semitendinosus muscles were higher for taurine but slightly lower for carnosine, coenzyme Q(10) and creatine. Values for all the compounds varied significantly between eight lamb muscles, possibly due in part to differences in the proportion of muscle fibre types. Slow cooking (90 min at 70 °C) of lamb longissimus and semimembranosus muscles led to significant reductions in the content of taurine, carnosine, and creatine (P<0.001), but a slight increase in coenzyme Q(10). There was also a four-fold increase in creatinine, presumably due to its formation from creatine. It is concluded that biologically, and possibly nutritionally, significant levels of taurine, carnosine, coenzyme Q(10), and creatine are present in beef and lamb, but that these levels vary between muscles, between animals, and with cooking.

The influence of growth potential or growth path on the tenderness of the longissimus muscle was investigated using 117 Angus and Angus-cross bulls and steers raised on pasture over two successive years. Growth rate for a period of 100 d from a weight of about 200 kg was used to identify the faster-growing two-thirds of cattle within the gender groups, half of which were grown fast to a slaughter weight of 530 kg at 16 to 18 mo of age (the Fast group), whereas the other half were restricted in growth (the Restricted group) so they attained a similar final weight as the slower-growing third (the Slow group) at about 26 mo of age. The Restricted group was included to determine whether the tougher meat expected from the Slow group relative to the Fast group (based on previous results) was due to the greater age of the Slow group or to their slower early growth rate. Beef from the Fast group was tenderer than that from both the Slow and Restricted groups based on sensory panels (P < 0.05) and objective measures (P < 0.05), indicating that the early growth-rate potential was less important than the differences in age or the patterns of growth for the Slow and Restricted groups. Improved tenderness for the Fast group was associated with more intramuscular fat (P < 0.05) and higher myofibrillar fragmentation indexes (P < 0.05). Patterns of tenderness differences between treatment groups were similar for bulls and steers, but beef from bulls was tougher (P < 0.001) than that from steers. The more tender beef from steers was associated with a slightly lower ultimate pH (P < 0.001), higher myofibrillar fragmentation indexes (P < 0.001), and more intramuscular fat (P < 0.001). Ultimate pH affected beef tenderness (P < 0.01), but adjustments to a constant pH did not decrease differences between treatment and gender groups. The higher growth rates (P < 0.01) and leaner carcasses (P < 0.01) of bulls compared with steers were consistent with other studies. Increases in age of 8 to 10 mo may be associated with less tender beef for cattle finished on pasture, and beef from bulls is likely to be less tender than that from steers.

Relationships between muscularity and muscle to bone ratio were investigated for beef carcasses of several breeds and crosses, and three genders using data from Bristol and Alberta. Side dissection data in terms of muscle, fat and bone weights were used to calculate muscle to bone ratios (MtoB) and muscularity indexes (MUSC) for the whole side or for the region around the femur bone. Highly significant breed and gender effects on MtoB and MUSC were shown for both the Bristol and the Alberta data sets, but the group differences for MtoB were not the same as those for MUSC despite the fact that these two characteristics were closely correlated. For both sets of data, for example, MUSC values at a common muscle plus bone weight were significantly higher for carcasses of bulls than heifers, but similarly adjusted MtoB values were generally higher for carcasses of heifers than bulls. Differences among breed groups were mainly in a similar direction for MUSC and MtoB, but the size of the differences varied widely. For example, relative to the Friesian, the Jersey breed had a significantly higher MtoB but a significantly lower MUSC, and carcasses of double-muscled bulls had a femur-region MtoB that was 19.2% greater than that of a group of Shorthorn-cross carcasses, but a MUSC that was only 1.7% higher. These findings show that because of the inconsistent relationships between muscularity and muscle to bone ratio among different classes of beef carcasses, lean meat yield cannot always be predicted without bias if measures of carcass shape are used as indicators of muscle to bone ratio.

This study assessed whether relationships between sensory and objective measures of beef tenderness were different for beef from bulls and steers. Trained panelists and instruments were used to measure tenderness of m. longissimus thoracis from bulls (n=58) and steers (n=59). Four measures of sensory tenderness (hardness, cohesiveness, toughness and chewiness) were closely correlated with each other, and moderately correlated with mechanical measures using a Warner-Bratzler device, a MIRINZ tenderometer and a compression cell in an Instron device. With increasing values of objective measures, sensory scores increased at a decreasing rate. Use of a general-least-squares model with sensory measures as the dependent variable and objective measures as covariates (linear and quadratic), showed that, after adjustment to a constant objective measure, significant differences between bulls and steers in sensory measures of toughness remained (P<0.001). Adjusted sensory measures also decreased with increasing ultimate pH in some instances. The bull/steer effects on adjusted sensory measures were smaller when regressions were fitted within the two groups. It is concluded that when using a common prediction equation to estimate sensory scores from objective measures, it can be expected that groups or individual samples with higher scores will tend to be under-estimated, and those with lower scores, over-estimated.

Previous studies have shown that, provided cold-shortening conditions are avoided, increases in ultimate pH from a normal of about 5.5 for beef M. longissimus thoracis (LT) are associated with increased cooked meat shear forces to an intermediate pHu of about 6 and then decreases in shear force with further increases to 7. The current study with LT samples from 156 cattle (40 steers, 116 bulls) investigated this relationship following 1 and 20 days ageing at 1-2°C. The patterns of change in shear values with increasing pHu were similar for both ageing times with a peak at just under 6, but the difference between 20 and 1 day samples (1-20 days) varied so that the relationship between pHu and this difference also showed a peak at intermediate pHu values. In contrast to some previous studies, sarcomere length did not decrease as pHu increased from 5.5 to 6, indicating that it is not necessarily an important determinant of toughening over this pHu range. A myofibrillar fragmentation index (MFI) increased from 1 to 20 day ageing, but the extent of the change was similar as pHu increased from 5.5 to 6.2. Over the wider range in pHu from 5.5 to 7 MFI at 1 day remained essentially constant while that at 20 days, and consequently the increase from 1 to 20 days, increased. These results do not provide evidence that any one factor is responsible for the greater toughness of beef with an intermediate pH, and suggest that factors other than degree of muscle fibre contraction and extent of myofibrillar protein breakdown may be involved.

Previous studies involving fetal decapitation or hypophysectomy, and the treatment of neonates with hormones or antibodies, have suggested that changes in pituitary hormone status during the perinatal period may influence later body composition. In the present study, rats were treated for the first 21 days of life with twice daily subcutaneous injections of saline, recombinant bovine growth hormone (bGH) or pituitary ovine prolactin (oPRL). The bGH and oPRL were administered at doses of 0.2 or 0.4 microgram/g bodyweight/day. One-third of the rats in each treatment group were slaughtered at each of days 21, 60 and 120 of life and measurements made of: length and weight of the body; weights of bones and muscle groups in the hindlimb; weights of four fat depots (120-day group only); and the content of nitrogen (N) and fat in the carcass. bGH, but not oPRL, treatment increased weight of the femur and humerus (across ages) but neither treatment had marked effects on weights of muscle groups, carcass weight or carcass N content at any age. Both bGH and oPRL treatment significantly reduced weight of the subcutaneous scapular fat depot and reduced carcass fat content, but only in animals aged 120 days (i.e. 99 days after the cessation of treatment). It is concluded that treatment of rats with bGH and oPRL during the immediate postnatal period specifically retards the ability of animals to deposit body fat in later life by mechanisms which differ from those involved in the classical lipolytic/antilipogenic effects of bGH.

In order to compare characteristics of lamb carcasses with superior muscularity (the European E class) with carcasses that did not fit the E specification, 114 E carcasses were individually matched for weight and fatness class with 114 Non-E carcasses. The carcasses (mean weight = 17 kg) were processed under commercial conditions into six trimmed, boneless cuts of the leg and saddle (inside, outside, knuckle, rump, striploin and tenderloin) and two bone-in cuts (hind-shank and 7-rib rack). After adjustment for carcass weight, fatness (as assessed by fat depth C and tissue depth GR) and sex, the E-class group, relative to the Non-E group, had a 4.3% higher yield of leg and saddle cuts, a 14.2% higher leg muscularity index calculated from the weights of trimmed boneless cuts around the femur and femur length, a 13.6% higher muscle to bone ratio in the femur region, an 8.2% greater 'eye'-muscle depth (B), and a 3.7% greater 'eye'-muscle width (A) (all P < 0.001). All boneless cuts except the knuckle were heavier for the E group. Carcasses of female lambs had legs with higher muscle to bone ratios and a higher yield from the leg plus saddle (both P < 0.01), but the muscularity index was similar between sexes. It is concluded that although lamb carcasses subjectively selected as having higher muscularity will yield slightly more meat, this difference will be small compared with the greater muscle depth relative to bone length. The importance consumers attach to carcass or cut shape over and above any association with meat yield needs to be assessed.

Arbitrary age limits and offal weights are often used to classify meat and offals from 'bobby' calves as 'immature' and hence unfit for human consumption. Such age limits were not scientifically validated in a comparative study of the ante mortem characteristics, and the physical characteristics of the carcases and offals of groups of Jersey calves aged one, five, 14 and 21 days. The quality characteristics of muscle (pH and water-holding capacity) did not change with increasing age, and the changes in chemical composition (water, protein, fat and ash) were minimal, particularly between the five-day-old and 21-day-old groups. Small changes in muscle colour measured objectively were not detectable visually.

Characteristics of the meat of 15-18-month Southdown rams from lines selected for high or low backfat depths (assessed ultrasonically at position C over the last rib) were compared. Half of the carcasses were electrically stimulated (ES) and within each carcass post-mortem treatments chosen to produce effects on meat tenderness were ageing periods of 1 or 15 days (Semimembranosus), early or delayed chilling (Biceps femoris), and trimming of the s.c. fat cover (Longissimus dorsi). These treatments had the expected effects on shear values, but the sizes of the effects were little affected by selection line or ES treatment. Selection line did not have any direct effects on shear values, reflectance values at several wavelengths, waterholding capacity, cooking loss or sarcomere length. The Semitendinosus muscle had a higher proportion of predominantly oxidative fibres for the high-backfat line, based on succinic dehydrogenase activity (P < 0·05), but there was no line difference in alkaline-stable ATPase activity in the same muscle. Muscle fibre diameter was similar for the two lines., (Copyright © 1992. Published by Elsevier Ltd.)

Samples of longissimus dorsi muscle from 150 cattle comprising Friesian bulls and steers and Charolais × Angus cross steers, were used to investigate the nature of the relationship between ultimate pH and beef tenderness under conditions where cold-shortening was avoided. A modified Warner-Bratzler (WB) shear machine with a square- rather than a vee-blade enabled several aspects of tenderness to be evaluated, including peak force (PF), initial yield force (IY), PF-IY, and an index of total work done. The two steer groups differed little in meat quality characteristics, but, in terms of six major hindquarter cuts, the Charolais cross group yielded 14·3% more meat per unit live weight, due to a combination of a superior dressing-out percent and a higher cutability. Relative to Friesian steers, the bulls produced beef with a higher ultimate pH (P < 0·001), and after adjustment to a common pH, the bull beef was tougher for all WB parameters except PF-IY. Cooking loss was higher for beef from bulls after adjustment for pH. Although reduced by pH adjustment, beef from bulls remained significantly darker than that from steers (P < 0·05) based on reflectance measurements. Maximum toughness in terms of PF, IY, and work index was at an ultimate pH of 6·0-6·1, but the peak was much less clear for PF-IY. The decline in tenderness with an increase in ultimate pH to 6·2 was associated with a decrease in sarcomere length. This result supports a previous suggestion that shortening explains, at least in part, the lower average tenderness at intermediate pH values., (Copyright © 1993. Published by Elsevier Ltd.)

Castrate yearling male sheep were treated for 8 weeks with either 50 micrograms/kg body wt/8 hourly sc insulin-like growth factor-I (IGF-I) (n = 10) or with saline (n = 9). IGF-I treatment increased plasma IGF-I from 235 +/- 17 to 347 +/- 16 ng/ml (P less than 0.001). There was a gradual divergence in body wt (P less than 0.10) between treatment groups. Food intake did not change significantly. The weight of the spleen corrected for body wt increased by 40% (P less than 0.001) and there was a marginal increase in adjusted kidney wt (P less than 0.1). There was no effect of IGF-I on carcass weight or dimensions, or on long bone length, although the weight per unit length of the tibia (P less than 0.05) and femur (P less than 0.10) were increased. There was no effect on wool growth. Plasma IGF binding proteins (IGFBPs) were quantified by ligand blot analysis. In the IGF-I treated group, IGFBP-1 showed a transient increase (P less than 0.05) at day 3 but was similar in both groups at day 55 of treatment. IGFBP-2 was suppressed (P less than 0.05) by day 55 and IGFBP-3 and 4 did not change. Plasma glucose was elevated (P less than 0.05) and plasma insulin was suppressed (P less than 0.01) from 280 +/- 32 pg/ml to 124 +/- 30.4 pg/ml, plasma urea (P less than 0.01) and creatinine (P less than 0.05) were reduced in the IGF-I treated group. The somatogenic effect of IGF-I in this study was minimal suggesting that in the well fed animal with an intact somatotropic axis IGF-I treatment at doses which double plasma IGF-I does not enhance somatic growth performance. However, the marked splenomegaly shows the sensitivity of splenic growth to systemic IGF-I. The suppression of insulin with chronic IGF-I treatment was accompanied by hyperglycaemia--this may explain in part the lack of a significant anabolic response and may limit the utility of IGF-I therapy unless higher doses with insulin-like effects are used.

A measure of muscularity, based on objective measurements, and expressed in terms of muscle depth relative to skeletal dimensions, is proposed and investigated using a simulation model. Average muscle depth is assessed as the square root of the muscle weight per unit length of a bone adjacent to the muscle. Muscularity is then defined as average muscle depth divided by bone length. Evidence based on a theoretical model, results from the literature and data from backfat selection lines of Southdown sheep is used to illustrate how muscularity defined in this way changes with growth, and the extent to which it parallels changes in muscle to bone ratio. It is concluded that although these two characteristics often change together there are situations where differences in muscularity are not accompanied by differences in muscle to bone ratio and vice versa., (Copyright © 1991. Published by Elsevier Ltd.)

Samples of M. longissimus dorsi from 16-20 month Friesian bulls or steers (80/group) were assessed for a range of meat quality characteristics after being held at ambient temperature for 24h (to avoid cold-shortening) and then at 0-2°C for 6 days. Mean ultimate pH was significantly higher for samples from the bulls (6·35 versus 5·89), and as a consequence, reflectance values were lower, sarcomere lengths were shorter, and expressed juice and cooking losses were lower. Mean Warner-Bratzler shear values did not differ between the groups, apparently because the bull values were mainly above the peak of the pH/shear force curve, while the steer values were mainly below it. There was no evidence that the relationship between shear force and pH differed for samples from the bulls and steers. Results suggested that the increased shear force with increased pH up to 6·2 was at least partly due to a decreased sarcomere length. It is suggested that some of the differences in tenderness between beef from bulls and steers, that have been reported elsewhere, may have been largely due to differences in ultimate pH values., (Copyright © 1990. Published by Elsevier Ltd.)

Effects of photoperiod on growth, carcass composition and serum concentrations of prolactin, growth hormone and cortisol were determined in prepubertal and postpubertal Holstein heifers. Forty-two prepubertal (avg body wt 84 +/- 3.0 kg) and 42 postpubertal (avg body wt 303 +/- 7.1 kg) Holstein heifers were utilized. Ten prepubertal and 10 postpubertal heifers were slaughtered before treatment began to obtain initial carcass data. The remaining 32 prepubertal and 32 postpubertal heifers were paired by body weight and randomly assigned to short-day (8 h of light: 16 h of dark) or long-day (16 h of light: 8 h of dark) photoperiods. After exposure to treatments for an average of 139 d, 10 prepubertal and 10 postpubertal heifers from each photoperiod treatment were slaughtered. In prepubertal heifers, photoperiod did not affect (P greater than .10) average daily body weight gain, carcass weight, carcass composition, accretion of carcass fat and carcass protein, or serum concentrations of prolactin, growth hormone or cortisol. However, prepubertal heifers exposed to long-day photoperiods had reduced (P less than .01) urinary N tau-methylhistidine excretion compared with heifers given short-day photoperiods. Postpubertal heifers exposed to short-day photoperiods had greater average body weight daily gain than animals exposed to long-day photoperiods. Although there was no effect of photoperiod (P greater than .10) on carcass or fat depot weights, postpubertal heifers exposed to short days had greater (P = .06) percentages of fat and reduced (P = .07) percentages of protein in the soft tissue of the 9-10-11 rib sections. Fat accretion was greater (P less than .05) in carcasses of postpubertal heifers exposed to short days than heifers given long-day photoperiods, but there was no effect (P greater than .10) of photoperiod on protein accretion. Photoperiod did not affect serum concentrations of growth hormone and cortisol, but serum prolactin tended (P less than .10) to be greater in postpubertal heifers exposed to long days. Under the conditions of this experiment, we conclude that exposure to short-day photoperiods stimulated body weight gain and fat accretion in postpubertal but not prepubertal Holstein heifers.

Muscle growth of male obese (ob/ob) and lean mice at 2, 3, 5 and 8 wk were analyzed on the basis of weights of gastrocnemius, plantaris and soleus muscles from each hind leg. The carcasses (prepared by removing skin, viscera, head, feet and tail) were analyzed for fat content so that the effect of phenotype on the relationship between muscle weight and fat-free carcass weight could be assessed. For each age group the obese mice had less muscle relative to fat-free carcass weight than lean mice, with the difference being significant at 3 wk (P less than .05) and 8 wk (P less than .025). The proliferative activity of muscle satellite cells in 2- and 3-wk-old obese and lean mice was measured on isolated muscle fibers by autoradiography. Muscle fiber diameter and number of nuclei/unit length were unaffected by phenotype, but the proportion of muscle nuclei showing proliferative activity was lower (P less than .01) in obese than in lean mice at 2 wk (1.05 vs 1.93%, respectively) and 3 wk of age (.23 vs .59%, respectively). These results are consistent with the suggestion that muscle growth is limited by satellite-cell proliferative activity, although direct evidence for a cause and effect relationship is not provided.

The nuclear content of skeletal muscles from lean and obese (ob/ob) male mice was investigated. Four lean and four ob/ob mice were examined at 2, 3, 5, 8, and 16 weeks of age. Differences in body weight between the two phenotypes were significant after 5 weeks of age. For all ages in the soleus and after 3 weeks of age in the gastrocnemius, muscle wet weight and length were less in ob/ob mice than in lean mice. Age did not influence the incidence of myonuclei in fiber cross sections for either muscle. Compared to lean mice the incidence of myonuclei per fiber cross section was significantly lower for ob/ob mice in the soleus muscle but not in the gastrocnemius muscle. The incidence of satellite cells in fiber cross sections and the percentage of nuclei within the basal lamina that were satellite cell nuclei decreased as age increased. Muscle fibers of ob/ob mice contained fewer myonuclei either because of shorter muscle length (gastrocnemius), or because of the combined effect of shorter muscle length and fewer myonuclei per unit length (soleus). The lower apparent number of myonuclei in the muscles of ob/ob mice was associated with a lower apparent number of satellite cells.

A cortisol radioimmunoassay in which unbound cortisol is partitioned into the organic phase of a toluene: water scintillation fluid mix at 0 to 5 degrees C is described. Antibody-bound cortisol remained in the aqueous phase. Since liquid scintillation spectrometers detect photons generated from the [3H]cortisol only in the organic phase, the system effectively separates antibody bound from unbound [3H]cortisol. Regression coefficients including linear, quadratic, and cubic components of standard curves were between 0.980 and 0.999. Cross-reactivity was 3% or less with 11 other steroids and cholesterol except for cortisone (16%) and prednisone (12%). Intra- and interassay coefficients of variation were 8 and 13%, respectively. The lower limit of sensitivity of the assay was 1.4 ng/ml. Recoveries of added mass averaged 97.5%. The correlation between concentrations of glucocorticoids assayed by competitive binding to dog plasma and the current procedure was 0.90. The assay procedure described simplifies separation of unbound from antibody-bound cortisol.

The observation that the subcutaneous fat of pasture-fed Southdown rams consists of two distinct regions is reported. Fatty acid composition of fat from the outer and inner regions of subcutaneous tissue taken from the rib region of eight Southdown rams fed pasture were determined. Relative to the harder inner regions (mean melting point 43.1 degrees C), the softer outer regions (mean melting point 31.8 degrees C) were shown to contain more 9:0-, 15:0-, 17:0-, 17:1-, 18:1-cis and total 18:1 fatty acids; less 14:0-, 16:0-, 18:0- and 18:1-trans fatty acids; and a greater variety and a greater concentration of branched-chain components. Proportions of medium chain-length fatty acids, other than 9:0, did not differ between the layers. The fatty acid contents of serial samples taken at 1-mm intervals through these tissues were determined. Changes in concentrations of components among samples were gradual through the tissues. There was no clear connective tissue sheet, as has been reported for pigs. The inner region of the tissues contains apparently nonrandom fluctuating changes in fatty acid composition.