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Over 40 days, lambs were fed: concentrate (C), concentrate containing 20% linseed (L), concentrate containing 35% olive cake (OC), or concentrate containing 10% linseed and 17% olive cake (OCL). The polyunsaturated fatty acids (PUFA) and peroxidation index (PI) in phospholipids were increased by the L and OCL treatments (P=0.007 and P=0.003, respectively). The OC and OCL diets increased the concentration of tocopherol in muscle (P<0.001). Compared to the OC and OCL diet, the L diet increased fatty acid oxidation, measured as conjugated dienes (CD; P=0.003), peroxides (PV; P<0.001) and TBARS (P=0.002) in minced muscle over 11 days of storage in high-oxygen atmosphere. Also, the L diet increased (P<0.001) the levels cholesterol oxidation products (COPs). In conclusion, feeding olive cake improved the oxidative stability of lamb meat and the combination of olive cake and linseed improved the fatty acid composition of meat without compromising its oxidative stability., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Colour and lipid stability of M. longissimus dorsi (LD) from sheep fed diets containing different lipid sources (Megalac (MG), camelina oil (CO), linseed oil (LO), NaOH-treated camelina seed (CS), NaOH-treated linseed (LS) or CO treated with ethanolamine (CA)) were examined. After 100 days on-feed, samples of LD were collected, fatty acid profile determined and colour and lipid oxidation (2-thiobarbituric acid reactive substances; TBARS) measured during retail display in high oxygen packaging. The LS ration was most effective in increasing the 18:3n-3 and conjugated linoleic acid (CLA) concentration in muscle. Within camelina, CA resulted in the highest 18:3n-3 and lowest CLA concentration in muscle. There was no difference in colour stability. Oil (seed) supplementation increased TBARS compared to MG in the early part of display while linseed-based rations tended to cause higher TBARS than camelina-based rations. Higher muscle 18:3n-3 concentration was associated with higher oxidation during early retail display but this was not reflected in a loss of colour stability., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

There is a need for new, non-invasive, rapid and reliable analytical methodologies that can easily be implemented and used for authentication of cattle production systems and the meat derived from them. Easily quantifiable markers could strengthen the current tracing methods for beef authentication. This study investigated the use of a nuclear magnetic resonance-based metabolomic approach as a tool to authenticate beef on the basis of the pre-slaughter production system. Urine and muscle samples were collected from animals fed either pasture outdoor, a barley-based concentrate indoor, silage followed by pasture outdoor or silage followed by pasture outdoor with concentrate over 1 year. A metabolomic analysis was performed on urine (n = 68) and muscle (n = 98) samples collected from animals on the different diets. The results showed that separation according to production system was possible indicating the potential use of this approach in beef authentication. Identification of the major discriminating peaks in urine led to the identification of potential markers of production system including creatinine, glucose, hippurate, pyruvate, phenylalanine, phenylacetylglycine and three unassigned resonances.

Stable isotope analysis of hair has found applications in many fields of science because it provides a temporally resolved, fairly stable isotopic archive of mammalian individuals. We investigated whether this hair archive is modified by natural weathering while attached to a living animal. We analyzed the tail switch hairs of one suckler cow, sampled seven times over a period of four annual summer pasture-winter stall feeding cycles. We compared relative isotope ratios (δ²H, δ¹³C, δ¹⁵N, δ¹⁸O and δ³⁴S) of sections of hair that grew simultaneously but were exposed to natural weathering conditions over different periods of time. Natural wear caused a loss of mass of approx. 0.13% day⁻¹, with no apparent effect of environmental conditions. Changes in δ²H, δ¹³C, δ¹⁵N and δ¹⁸O were below the detection limit, indicating that hair is a reliable archive for the isotopes of these elements. In contrast, δ³⁴S values increased during the grazing period by about 1‰, with exposure to UV radiation appearing to have a major influence on this result. The δ³⁴S values decreased during the subsequent stall period, probably due to abrasion. Seasonal variation in δ³⁴S may indicate alternating environments that differ in their weathering conditions.

The present study was designed to assess the balance between antioxidant and prooxidant components and the oxidative stability of beef from cattle fed exclusively grazed pasture (PAS) or a barley-based concentrate offered indoors (CONC) for 11 mo, or fed grass silage indoors for a 5-mo winter period, followed for the remaining 6-mo summer period by grazed pasture (SiP) or by grazed pasture plus concentrate at 50% of the dietary DM (SiPC). Muscle prooxidant and antioxidant components were determined by measuring fatty acids and α-tocopherol concentration of LM, respectively. Lipid oxidation and color stability were monitored in ground LM, packaged in a high-oxygen modified atmosphere, over 11 d of refrigerated storage. Vitamin E concentration decreased (P < 0.0005) with an increasing proportion of concentrate in the diet (2.59, 2.45, 1.76, and 1.15 μg/g for PAS, SiP, SiPC, and CONC, respectively). A greater proportion of PUFA was found in LM from cattle in the PAS, SiP, and SiPC groups compared with animals in the CONC group (9.62, 11.04, 8.96, and 6.94%, respectively; P < 0.0005). A greater concentration of highly peroxidizable PUFA was found in LM from heifers in the PAS, SiP, and SiPC groups compared with those in the CONC group (0.84, 0.85, 0.87, and 0.65 mg/g of muscle, respectively; P = 0.02). Dietary treatment affected lipid oxidation (P < 0.0005), with greater 2-thiobarbituric acid reactive substance values in beef from heifers in the SiPC group than in beef from those in the PAS, SiP, and CONC groups. Dietary treatment affected myoglobin oxidation (P = 0.002) during storage, with greater metmyoglobin accumulation in beef from animals receiving concentrate (CONC and SiPC treatments) than in beef from cattle in the PAS and SiP groups. Consequently, feeding concentrate impaired meat color stability over the storage duration, with greater H* (hue angle) values (P < 0.0005) in meat from heifers in the SiPC and CONC groups compared with meat from those in the PAS and SiP groups. The results of the present study confirm a positive effect of grass-based feeding systems on meat color stability compared with concentrate-based dietary strategies. It appears that vitamin E in muscle alone does not explain the resistance of meat to oxidative deterioration because a clear interaction with highly peroxidizable PUFA exists.

Stable sulphur isotope ratios ((34)S/(32)S) in animal tissues have been suggested as a tracer of coastal residency of terrestrial animals, but data are lacking that quantify the inland range of the sulphur coastal signal and the effects of seasonality. Here, we present δ(34)S measurements of sheep wool collected seasonally on eight farms across Ireland and wool samples collected opportunistically along the west and east coasts. We observed large (>10‰) δ(34)S differences across the island and we show that wool δ(34)S values were negatively correlated with distance to the west coast. We propose that this is due to the predominantly (south-)westerly airflow, possibly combined with the influence of anthropogenic sulphur deposited from the east. While essentially all the sulphur contained in west-coast wool is of marine origin, relatively high δ(34)S values were still measured >100 km inland, suggesting that marine sulphur can be carried over long distances. Seasonal variations are small at the individual level for sedentary grazing animals. We conclude that sulphur isotopes ratios measured in archival keratinous tissues can be used to describe regional δ(34)S isoscapes primarily defined by distance to coasts and thus provide a tool to detect short-term movements of domestic, feral and wild animals within such isoscapes., (Copyright © 2011 John Wiley & Sons, Ltd.)

Our hypothesis was that carotenoids in bovine subcutaneous adipose tissue (SAT) together with colour and reflectance spectra could be used to differentiate between beef production systems based on grass, concentrates or combinations thereof. SAT was sampled from the carcasses of heifers fed pasture (P), a barley-based concentrate (C), silage followed by pasture (SiP) or silage followed by pasture with concentrate (SiPC). β-carotene in the SAT from the C group (0.09 μg g(-1)) was lower (P<0.05) than that from the P (0.54 μg g(-1)), SiP (0.49 μg g(-1)) and SiPC (0.49 μg g(-1)) groups. Lutein in the SAT differed (P<0.05) between all groups with 0.13, 0.10, 0.08 and 0.04 μg g(-1) for the P, SiP, SiPC and C groups, respectively. Principal component analysis of the carotenoid data, SAT colour variables ['L', 'a', 'b', 'C', 'H'] and the reflectance data made it possible to distinguish between the animals fed a barley-based concentrate diet and the animals fed pasture-based diets, but not between different pasture-based groups., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Beef heifers (n = 48) were offered, daily, a 1.5 kg ration that contained 0, 69, 138, and 275 g of ruminally protected fish oil (RPFO) fortified with vitamin E (5000 IU/kg). The fatty acid profile of neutral (NL) and polar lipids (PL) of neck muscle was analyzed by GC-FID. Minced muscle was displayed in an 80% O(2):20% CO(2) atmosphere under simulated retail display conditions. Muscle α-tocopherol concentrations did not differ. For PL, the proportions of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) increased (P < 0.05, linearly and quadratically, respectively). For NL, the proportion of EPA was not affected but DHA increased linearly and quadratically (P < 0.05). Supplementation did not affect color stability of ground beef, but lipid oxidation was higher (P < 0.001) for 275 g of RPFO on day 10 of display. In conclusion, supplementation with RPFO increased muscle EPA and DHA with no effect on color stability while lipid oxidation was increased only at the highest level of supplementation, after prolonged display.

Multielemental (C, N, H, S) stable isotope ratio analysis was used as an analytical tool to verify the geographical origin of beef from several European and non-European countries. Beef samples were collected from nine different countries, and the (13)C/(12)C, (15)N/(14)N, (2)H/(1)H, and (34)S/(32)S ratios of defatted beef were measured using isotope ratio mass spectrometry (IRMS). There were highly significant differences in the mean isotopic values of the beef from different countries. The results of discriminant analysis showed that the four isotope ratios were significant for the discrimination of geographical origin and that 84.9% of the samples were correctly assigned to the country of origin (82.2% when cross-validated). Beef was also classified according to geographical origin when additional information on different feeding regimens used in Ireland was included, with 85.0% of the samples correctly allocated and 82.9% cross-validated using the isotopic signatures. All of the Irish beef samples verifiable as pasture-fed beef were correctly classified and then cross-validated.

Stable isotope ratio analysis (SIRA) was used as an analytical tool to verify the preslaughter diet of beef cattle. Muscle and tail hair samples were collected from animals fed either pasture (P), a barley-based concentrate (C), silage followed by pasture (SiP), or silage followed by pasture with concentrate (SiPC) for 1 year (n = 25 animals per treatment). The (13)C/(12)C, (15)N/(14)N, (2)H/(1)H, and (34)S/(32)S isotope ratios in muscle clearly reflected those of the diets consumed by the animals. By applying a stepwise canonical discriminant analysis, a good discrimination of bovine meat according to dietary regimen was obtained. On the basis of the classification success rate, the (13)C/(12)C and (34)S/(32)S ratios in muscle were the best indicators for authentication of beef from animals consuming the different diets. Analysis of (13)C/(12)C and (15)N/(14)N in tail hair sections provided an archival record of changes to the diet of the cattle for periods of over 1 year preslaughter.

The aim of this study was to determine the effect of different diets on beef meat volatile organic compounds (VOC). Seven heifers grazed pasture for twelve months (group P); 8 heifers received grass silage ad libitum indoors for six months and then were switched to pasture for six months (group SiP); 8 heifers received grass silage ad libitum indoors for six months and then switched to pasture and also offered 0.5 of the diet dry matter of concentrate for six months (group SiPC); 8 heifers received concentrate for twelve months (group C). The muscle longissimus dorsi was sampled at slaughter and subjected to VOC analysis by SPME-GC-MS. Some aldeyhdes, ketones and furans deriving from lipid oxidation were affected by the treatments. Skatole, 3-undecanone, cuminic alcohol and 1-butanol, 2-methyl allowed the discrimination between animals fed concentrate from animals fed non-concentrate diets. Germacrene D, a terpenoid, was a marker of grass feeding., (Copyright © 2010 The American Meat Science Association. Published by Elsevier Ltd. All rights reserved.)

The objective of this study was to evaluate the impact of diets enriched with plant oils or seeds, high in polyunsaturated fatty acids (PUFA), on the fatty acid profile of sheep intramuscular and subcutaneous adipose tissue (SAT). Sixty-six lambs were blocked according to initial body weight and randomly assigned to six concentrate-based rations containing 60 g fat/kg dry matter from different sources: (1) Megalac (MG; ruminally protected saturated fat), (2) camelina oil (CO), (3) linseed oil (LO), (4) NaOH-treated camelina seed (CS), (5) NaOH-treated linseed (LS) or (6) CO protected from ruminal saturation by reaction with ethanolamine; camelina oil amides (CA). The animals were offered the experimental diets for 100 days, after which samples of m. longissimus dorsi and SAT were collected and the fatty acid profile determined by GLC. The data were analyzed using ANOVA with 'a priori' contrasts including camelina v. linseed, oil v. NaOH-treated seeds and CS v. CA. Average daily gain and total fatty acids in intramuscular adipose tissue were similar across treatments. The NaOH-treatment of seeds was more effective in enhancing cis-9, trans-11 conjugated linoleic acid (CLA) incorporation than the corresponding oil, but the latter resulted in a higher content of trans-11 18:1 in both muscle neutral and polar lipids (P < 0.01, P < 0.001, respectively). Inclusion of LS resulted in the highest PUFA:saturated fatty acid (SFA) ratio in total intramuscular fat (0.22). The NaOH-treatment of seeds resulted in a higher PUFA/SFA ratio (0.21 v. 0.18, P < 0.001) than oils and on average, linseed resulted in a higher PUFA/SFA ratio than camelina (P < 0.01). Lambs offered LS had the highest concentration of n-3 PUFA in the muscle, while those offered MG had the lowest (P < 0.001). This was reflected in the lowest (P < 0.001) n-6: n-3 PUFA ratio for LS-fed lambs (1.15) than any other treatment, which ranged from 2.14 to 1.72, and the control (5.28). The trends found in intramuscular fat were confirmed by the data for SAT. This study demonstrated the potential advantage from a human nutrition perspective of feeding NaOH-treated seeds rich in PUFA when compared to the corresponding oil. The use of camelina amides achieved a greater degree of protection of dietary PUFA, but decreased the incorporation of biohydrogenation intermediates such as cis-9, trans-11 CLA and trans-11 18:1 compared to NaOH-treated seeds.

Fifty-six spring calving Holstein-Friesian dairy cows (body weight=607 kg and body condition score=2.75), destined for culling, were randomly assigned to one of four experimental treatments. Cows were confirmed non-pregnant by rectal palpation. The experiment was split into two periods: over-wintering period (OWP) and spring finishing period (SFP). Animals were assigned to one of four treatments: a control group (C) was slaughtered after am milking on day 0; three dietary treatments, two of which were dried pre-experiment; ad libitum grass silage (GS+G); 75% grass silage and 25% straw (GS+S); and one with the extended lactation concept applied, cows were offered grass silage plus 6 kg concentrate DM/cow/day and milked twice daily (EXTLAC). EXTLAC cows were dried-off 1 week prior to turnout. The OWP lasted 84 days. Subsequent to the OWP cows were turned out to pasture (SFP). All cows were finished to a pre-defined carcass specification; >272 kg cold carcass weight, P+carcass conformation class and 3 carcass fat class. Over the entire experimental period, average daily gain (ADG) was lower (P<0.001) for the EXTLAC treatment compared with the two other dietary treatments. The GS+G treatment finished 33 and 38 days (P<0.001) earlier than the GS+S and EXTLAC treatments, respectively. Total feed utilized on a DM basis was 1.9, 2.0 and 2.5 tonnes/cow for the GS+G, GS+S and EXTLAC dietary treatments, respectively. All finishing treatments resulted in a significant improvement in carcass weight, as well as carcass quality traits, compared to the C group. A significant improvement occurred in muscle redness between the C group and treatments offered a finishing period prior to slaughter., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Background: Despite an increasing preference of consumers for beef produced from more extensive pasture-based production systems and potential human health benefits from the consumption of such beef, data regarding the health status of animals raised on pasture are limited. The objective of this study was to characterise specific aspects of the bovine peripheral and the gastrointestinal muscosal immune systems of cattle raised on an outdoor pasture system in comparison to animals raised on a conventional intensive indoor concentrate-based system., Results: A number of in vitro functional tests of immune cells suggested subtle differences between the animals on the outdoor versus indoor production systems. There was a decrease in the number of neutrophils and monocytes engaged in phagocytosis in outdoor cattle (P < 0.01 and P < 0.05, respectively) in comparison to those indoors. Following mitogen stimulation, a lower level of interferon-gamma was produced in leukocytes from the outdoor animals (P < 0.05). There was evidence of a gastrointestinal nematode infection in the outdoor animals with elevated levels of serum pepsinogen (P < 0.001), a higher number of eosinophils (P < 0.05) and a higher level of interleukin-4 and stem cell factor mRNA expression (P < 0.05) in the outdoor animals in comparison to the indoor animals. Lower levels of copper and iodine were measured in the outdoor animals in comparison to indoor animals (P < 0.001)., Conclusion: Despite distinctly contrasting production systems, only subtle differences were identified in the peripheral immune parameters measured between cattle raised at pasture in comparison to animals raised on a conventional intensive indoor concentrate-based production system.

Evidence is growing that the range of zinc stable isotope compositions, represented by the deviation of (66)Zn in permil units relative to a standard and expressed as delta(66)Zn, is larger in organic matter than in inorganic material. This study reports the variations of delta(66)Zn in various organs of sheep raised on a controlled diet. Zinc was purified by anion-exchange chromatography. The Zn concentrations and Zn stable isotope compositions were determined by quadrupole inductively coupled plasma mass spectrometry and multi-collector inductively coupled plasma mass spectrometry, respectively. The data show that delta(66)Zn variability exceeds 1 per thousand, with bone, muscle, serum and urine enriched in the heavy isotopes, and feces, red blood cells, kidney and liver enriched in light isotopes, all relative to the diet value. The (66)Zn enrichment of the circulating serum reservoir is likely to take place in the digestive tract, probably through the preferential binding of lighter isotopes with phytic acid, which is known to control the uptake of metallic elements. Mass balance calculations suggest that the (66)Zn depletion between diet and feces, which is not balanced by any other outward flux, leads to a secular isotopic drift in serum. A simple time-dependent two-box model, involving the gastro-intestinal tract on the one hand and the muscle and bone on the other, predicts that the maximum (66)Zn enrichment, which equals the difference in delta(66)Zn between diet and bulk (approximately 0.25 per thousand), is reached after about ten years. Therefore, a better understanding of the variations of natural abundance of Zn isotopes in animals and humans will probably bring new perspectives for the assessment of their Zn status., (Copyright 2010 John Wiley & Sons, Ltd.)

Fourteen male Comisana lambs were divided into two groups at 45days of age and were individually penned for 105days. Over this period, seven lambs were fed a concentrate-based diet (C), whereas the remaining animals received vetch (Vicia sativa; H) harvested daily and given fresh to the animals. Lipid oxidation was measured in both minced cooked meat (semimembranosus muscle, SM) over 4days of aerobic refrigerated storage and on minced raw meat stored over 14days in a high oxygen atmosphere. Colour descriptors, haem pigment concentration, and metmyoglobin percentages were also determined during storage duration on the minced raw meat. Lipid oxidation increased over time in cooked and raw meat (P<0.0005), but lower TBARS values were found in both cooked and minced meat from lambs fed vetch compared to those given concentrates (P=0.001; P=0.006, respectively). Higher a* values, lower b* values and lower hue angle values were observed in meat from H-fed animals as compared to meat from C-fed lambs (P=0.006; P=0.02; P=0.005, respectively). Metmyoglobin formation increased over time (P<0.0005), but the H diet resulted in lower metmyoglobin percentages than the C diet (P=0.006). Haem pigment concentration decreased over the 14days of storage (P<0.0005). We conclude that, under conditions that promote oxidative stress in meat, a herbage-based diet can improve the oxidative stability of meat compared to a concentrate-based diet.

Stable isotope ratio analysis of light elements (including C, N, and S) is a powerful tool for inferring the production and geographic origins of animals. The objectives of this research were to quantify experimentally the isotopic turnover of C, N, and S in bovine skeletal muscle (LM and psoas major) and to assess the implications of the turnover for meat authentication. The diets of groups (n = 10 each) of beef cattle were switched from a control diet containing barley and unlabelled urea to an experimental diet containing maize, (15)N-labeled urea, and seaweed for periods of up to 168 d preslaughter. The feeding of the experimental diet was clearly reflected by the delta(13)C, delta(15)N, and delta(34)S values of the LM and psoas major muscles, but isotopic equilibrium was not reached in either muscle for C, N, or S after 168 d of feeding the experimental diet. The slow turnover in skeletal muscle was reflected by the C and N half-lives of 151 and 157 d for LM and 134 and 145 d for psoas major, respectively, and by an S half-life of 219 d in LM. It is concluded that the turnover of light elements (C, N, and S) in bovine skeletal muscles is a slow process; therefore, skeletal muscles contain isotopic information on dietary inputs integrated over a long period of time (months to years).

Fourteen male Comisana lambs were divided into two groups at 45days of age: lambs fed a concentrate diet (C), or lambs fed the same concentrate with the addition of quebracho (Schinopsis lorentzii) tannins (T). Sheep were slaughtered at 105days of age. Lipid oxidation, colour coordinates, haem pigment concentration, and metmyoglobin percentages were measured on minced semimembranosus muscle (SM) over 14days of refrigerated storage in a high oxygen modified atmosphere. Tannin supplementation increased (P<0.01) a(∗) values and reduced (P<0.01) b(∗) values of the SM when compared to C. Lower hue angles (P<0.001) and metmyoglobin formation (P=0.07) were observed in lamb from T-fed compared to C-fed sheep during the 14-days storage period. Furthermore, feeding T resulted in greater (P<0.001) haem pigment concentrations in the SM during refrigerated storage; however, diet had no (P=0.28) effect on lipid oxidation. Therefore, including quebracho tannins in sheep diets can improve meat colour stability of fresh lamb during extended refrigerated storage.

The colour of bovine subcutaneous (sc) adipose tissue (carcass fat) depends on the age, gender and breed of cattle. Diet is the most important extrinsic factor but its influence depends on the duration of feeding. Cattle produced under extensive grass-based production systems generally have carcass fat which is more yellow than their intensively-reared, concentrate-fed counterparts and this is caused by carotenoids from green forage. Although yellow carcass fat is negatively regarded in many countries, evidence suggests it may be associated with a healthier fatty acid profile and antioxidant content in beef, synonymous with grass feeding. Nonetheless, management strategies to reduce fat colour of grass-fed cattle are sought after. Current research suggests that yellow colour of this tissue is reduced if pasture-fed cattle are converted to a grain-based diet, which results in accretion of adipose tissue and dilution of carotenoids. Colour changes may depend on the initial yellow colour, the carotene and utilisable energy in the finishing diet, the duration of finishing, the amount of fat accumulated during finishing and the rate of utilisation of carotene from body fat. Differences in nutritional strategies which cause differences in fatty acid composition may be reflected by differences in fat colour and carotenoid concentration. Fat colour and carotenoids are prominent among a panoply of measurements which can aid the authentication of the dietary history and thus to some extent, the origin of beef, although this potential utility is complicated by the simultaneous rather than discrete use of forages and concentrates in real production systems.

Sixty-eight spring calving Holstein-Friesian dairy cows on completion of lactation were randomly assigned to one of four dietary treatments. The experiment commenced on 17th December 2005 and was completed on 27th June 2006. Pre-experimental live weight and BCS were 605kg (s.d. 68.9) and 2.7 (s.d 0.28), respectively. The four treatments were: ad-lib grass silage (GS), GS+3kg concentrate (GS+3), GS+6kg concentrate (GS+6) and GS+9kg concentrate (GS+9). All cows were finished to a live weight>620kg and a BCS>3.5. Live animal, carcass and meat quality characteristics were measured. Mean (s.d.) total feed utilized was similar, at 1.5 (0.05) tonnes DM/cow across all treatments. There was a linear (P<0.001) increase in ADG (kg/day) for the first three dietary treatments, GS (0.71), GS+3 (0.91), GS+6 (1.14) with no additional response to the final increment, GS+9 (1.15). As concentrate proportion in the diet increased there was a linear decrease (P<0.001) in days to slaughter. Cows on the GS+9 treatment (84 days) finished on average 12, 25 and 38 days earlier than those on the GS+6, GS+3, and GS treatments. The GS+9 treatment had lower carcass fat yellowness ('b' value) than the GS treatment but the GS+3 and GS+6 treatments did not differ from either GS or GS+9. There was no effect of treatment (P>0.05) on muscle redness ('a' value) following exposure to oxygen. When cull cows are finished to pre-defined slaughter criteria, similar carcass classifications and carcass quality can be achieved with diets ranging from GS to GS+9, however significant difference in physical performance and days to slaughter will result.

We present the results of a series of controlled feeding experiments with sheep, designed to investigate the effects of age and level of food intake on the kinetics of incorporation of the dietary carbon signal into wool. Four different groups of three sheep each, ranging in age from 6 to 78 months, were fed a C(3) diet and switched to a C(4) diet for up to 250 days. Different quantities of the same C(4) diet were provided to each group, in order to achieve different growth rates (high, low, and no growth). Wool was repeatedly shorn from each animal and processed for delta(13)C analyses. Results show that newly grown wool does not start recording the isotope composition of the new diet immediately after the diet-switch. The time-lag varies according to the age of the animal, from 6 +/- 1 days in lambs to up to 15 +/- 4 days in the older ewes. Wool from fast-growing lambs approached equilibrium faster than that from slow-growing lambs and young ewes, with old ewes being the slowest. However, 3 weeks after the diet-switch, the differences in wool delta(13)C values between the four different groups of animals were relatively small and represented less than 15% of the isotopic difference between the two diets. These results suggest that a single equation can be used to reconstruct previous diets for animals of different age, provided that the diet is similar and all individuals are in positive protein balance., (Copyright (c) 2008 John Wiley & Sons, Ltd.)

Forty-five Charolais crossbred steers were offered a common diet and accommodated either outside on wood-chips (OWP, 18m(2)/head) or in a naturally-ventilated building in slatted-floor pens (SLA, 2.5m(2)/500kg bodyweight) or in straw-bedded pens (STR, 4m(2)/head) for 132 days. Carcass weight averaged 351, 362, and 372 (sed 6.63)kg (P<0.05), for SLA, STR and OWP, respectively. Accommodation system did not affect the colour, drip loss, shear force or composition of Musculus longissimus dorsi (LD) or Musculus extensor carpi radialis (ECR) muscles or the sensory characteristics of LD. The ultimate pH of ECR was highest (P<0.05) for OWP steers, while their LD was darker at 2 days post-mortem than LD from STR steers. It is concluded that accommodating cattle on OWP had a minor transient effect on beef colour and no impact on beef composition or eating quality.

The effect of sunflower and fish oil supplementation of grazing heifers on lipid oxidation and colour stability in beef was investigated. For 150 days, heifers were assigned unsupplemented grazing (G) or restricted grazing with 2.5kg concentrates containing 1250I.U. α-tocopheryl acetate and 290g sunflower oil (S1), 415g sunflower oil (S2), 290g sunflower+85g fish oil (FS1) or 415g sunflower+85g fish oil (FS2). Longissimus dorsi muscle was excised 24h post-mortem and stored at -30°C prior to analysis. Muscle α-tocopherol in the oil-supplemented groups was higher (P<0.05) than the G group. Lipid oxidation in refrigerated, minced raw or cooked beef was not significantly affected by diet but metmyoglobin was higher (P<0.05) in raw beef from oil-supplemented groups compared to the G group. Lipid oxidation and metmyoglobin formation increased (P<0.001) during refrigerated storage. Vitamin E supplementation together with pasture grazing appeared to offset any potential deleterious effect of oil supplementation on lipid and colour stability.

Background: Recovering high quality intact RNA from post-mortem tissue is of major concern for gene expression studies in animals and humans. Since the availability of post-mortem tissue is often associated with substantial delay, it is important that we understand the temporal variation in the stability of total RNA and of individual gene transcripts so as to be able to appropriately interpret the data generated from such studies. Hence, the objective of this experiment was to qualitatively and quantitatively assess the integrity of total and messenger RNA extracted from bovine skeletal muscle, subcutaneous adipose tissue and liver stored at 4 degrees C at a range of time points up to 22 days post-mortem. These conditions were designed to mimic the environment prevailing during the transport of beef from the abattoir to retail outlets., Results: The 28S and 18S rRNA molecules of total RNA were intact for up to 24 h post-mortem in liver and adipose tissues and up to 8 days post-mortem in skeletal muscle. The mRNA of housekeeping genes (GAPDH and ACTB) and two diet-related genes (RBP5 and SCD) were detectable up to 22 days post-mortem in skeletal muscle. While the mRNA stability of the two housekeeping genes was different in skeletal muscle and liver, they were similar to each other in adipose tissue. After 22 days post-mortem, the relative abundance of RBP5 gene was increased in skeletal muscle and in adipose tissue and decreased in liver. During this period, the relative abundance of SCD gene also increased in skeletal muscle whereas it decreased in both adipose tissue and liver., Conclusion: Stability of RNA in three tissues (skeletal muscle, subcutaneous adipose tissue and liver) subjected to long-term post-mortem storage at refrigeration temperature indicated that skeletal muscle can be a suitable tissue for recovering biologically useful RNA for gene expression studies even if the tissue is subjected to post-mortem storage for weeks, whereas adipose tissue and liver should be processed within 24 hours post-mortem.

Multi-element (H,C,N,S) stable isotope ratio analysis was tested for its suitability as a means for geographical provenance assignment of lamb meat from several European regions. The defatted dry matter (crude protein fraction) from lamb meat was found to be a suitable probe for "light" element stable isotope ratio analysis. Significant differences were observed between the multi-element isotope ratios of lamb samples from different regions. The mean hydrogen isotopic ratios of the defatted dry matter from lamb were found to be significantly correlated with the mean hydrogen isotopic ratios of precipitation and groundwater in the production regions. Carbon and nitrogen isotopic ratios were influenced by feeding practices and climate. Sulfur isotopic ratios were influenced by geographical location and surface geology of the production region. The results permitted differentiation of lamb meat, from most production regions, by inspection. However, more sophisticated evaluation of the data using multivariate methods, such as linear discriminant analysis, achieved 78% correct classification.

Our objective was to determine the effect of oil supplementation of pasture fed, beef cattle on the fatty acids, particularly CLA and PUFA, of muscle and s.c. adipose tissue. Forty-five Charolais crossbred heifers were blocked on BW and randomly assigned to 1 of 3 dietary regimens in a randomized complete block design (n = 15). The 3 treatments were: unsupplemented grazing (GO), restricted grazing plus a sunflower oil-enriched ration (SO), or restricted grazing plus a linseed oil-enriched ration (LO). Heifers were fed the experimental diets for approximately 158 d. Samples of LM muscle and s.c. adipose tissue were taken postmortem, the muscle fat was separated into neutral lipid and polar lipid (no separation was performed on the s.c. adipose tissue), and the fatty acid profile was determined by GLC. No effect of dietary treatment on carcass weight or total fatty acid concentration (mean 2,571 mg/100 g of muscle) in muscle fat was detected. Heifers offered SO had a greater (P < 0.001) proportion of CLA and C18:1trans-11 (1.90 and 9.35 vs. 1.35 and 6.89 g/100 g of fatty acids, respectively) in neutral lipid of muscle fat compared with those offered LO, which had a greater proportion of CLA and C18:1trans-11 than heifers offered GO (0.78 and 3.37 g/100 g of fatty acids, respectively). Similar effects were observed in the polar lipid and s.c. lipid. The PUFA:SFA ratio was greater in muscle fat and s.c. adipose tissue from supplemented heifers than in those offered GO (P < 0.001). Compared with LO, the PUFA:SFA ratio was greater (P < 0.05) in muscle fat of heifers offered SO, but there was no difference between SO and LO for this ratio in s.c. adipose tissue. The n-6:n-3 PUFA ratio was similar in muscle and s.c. adipose tissue for GO and LO, but it was greater (P < 0.05) for SO. It is concluded that supplementation of pasture-fed cattle with plant oil-enriched concentrates resulted in an increase in beef fat of some fatty acids considered to be of benefit to human health. Concentrates enriched with sunflower oil were more effective in increasing the CLA concentration, whereas linseed oil-enriched concentrates resulted in a more favorable n-6:n-3 PUFA ratio. The relevance to human health of the associated increase in C18:1trans-11 merits investigation.

The objective of this study was to ascertain whether sequential sampling and isotopic analysis of bovine hooves could be used to reconstruct the dietary history of cattle. A controlled, on-farm experiment was conducted in which cattle were switched from a barley-based diet to an isotopically different diet incorporating maize, urea and seaweed (the isotopic spacing between diets was 13.6 per thousand for delta(13)C and 8.0 per thousand for delta(15)N) and maintained on that diet for 168 days. Postmortem sampling of the cleaned anterior wall of the lateral, left front claw was carried out on five individuals using a micro-drilling technique. From the first 60 mm of each claw, up to 41 samples with a spacing between them of less than 1 mm were collected. Bands were less than 1 mm deep and had a mean width of 1.2 mm. The hoof keratin showed a rapid increase followed by a slower increase in its delta(13)C and delta(15)N values following the diet switch, suggesting that C and N in hoof keratin originate from more than one pool. However, the response of the N isotope composition of the hoof was somewhat delayed compared with that of C. Estimated mean hoof growth rates for these cattle were 10.5 +/- 2.3 mm per month and 6.7 +/- 1.0 mm per month (+/-SD, n = 5) when receiving the barley-based transition diet and the maize-based experimental diet, respectively. These values are considerably higher than previous estimates obtained by visual methods and they suggest that diet may have a greater influence on hoof growth rates than seasonality. These results demonstrate that hooves are a suitable incremental tissue for high-resolution isotopic reconstruction of the dietary history of bovine animals., (Copyright (c) 2007 John Wiley & Sons, Ltd.)

To investigate the usefulness of bovine hooves as incremental tissues, the objective of this research was to gain a better understanding of hoof growth in three dimensions. In a controlled experiment, cattle were switched from a barley-based diet to a maize-based diet (C isotopic spacing between diets was 13.6 per thousand) and maintained on this experimental diet for 168 days. To compare growth rates along the hoof wall, three slices were sampled post-mortem from one bovine claw. In addition, one claw from each of three different animals was sampled at different depths from the surface to determine any possible time lag ('offset') in the laying down of keratin tissue layers. From each hoof as many as 41 superficial samples were taken over the first 60 mm, starting at the periople, and up to 12 samples were taken sequentially at increasing depths to a depth of 6 mm at five particular points on the surface. The growth rate of the abaxial wall of the bovine claw increased from the anterior to the posterior region of the bovine hoof. Analysis of the deep samples revealed that the deeper layers were younger than the surface layers. This offset was inversely related to the hoof growth rate, i.e. hooves with a high hoof growth rate showed a smaller offset. Observed offsets ranged between 9.2 +/- 1.8 days per mm in depth for a high and 14.0 +/- 2.8 days per mm in depth for a low hoof growth rate and were significantly different (t > or = 3.92, p < 0.0005, n = 19 or 27). The results of this study demonstrate that when sampling hooves or hoof fragments for applications such as diet reconstruction, careful consideration needs to be given to sample location., (Copyright (c) 2007 John Wiley & Sons, Ltd.)

The objective of this experiment was to determine the effect of dietary composition and duration of feeding on subcutaneous (s.c.) adipose tissue and M. longissimus dorsi (LD) colour and pigment concentrations of heifers. Fifteen heifers were permanently housed and fed a concentrate diet (PH-CON). Fifty-four heifers were grazed on pasture (PAS) for 90d, housed and offered concentrates (PAS-CON), 200g grass silage (GS)/kg dry matter (DM) (PAS-GS20), 500g GS/kgDM (PAS-GS50) or zero-grazed grass (PAS-GRA). To facilitate assessment of the temporal pattern of tissue colour, 3 heifers/treatment were slaughtered at housing (following 7d adjustment to diets) and 28, 56, 91 and 120 days thereafter. Yellowness ('b' value) of s.c. adipose tissue and lightness ('L' value) and redness ('a' value) of LD were recorded 48h post-mortem. β-Carotene and lutein contents of s.c. adipose tissue and total LD haem pigments were determined. At housing, s.c. adipose tissue 'b' values of the PAS group (mean=13.47) were higher (P<0.01) than those of the PH-CON group (mean=10.35) but there was no difference in β-carotene or lutein concentrations. The change in s.c. adipose tissue 'b' for each diet following housing was best described by the following equations: PH-CON: y=-0.087 (SE 0.0347) X+0.0005 (SE 0.00029) X(2)+10.06 (SE 0.600), MSE 1.94, R(2) 0.57, P<0.01. PAS-CON: y=-0.102 (SE 0.0286) X+0.0006 (SE 0.00024) X(2)+13.32 (SE 0.598), MSE 2.30, R(2) 0.62, P<0.001. PAS-GS20: y=-0.106 (SE 0.0296) X+0.0008 (SE 0.00025) X(2)+13.10 (SE 0.618), MSE 2.46, R(2) 0.47, P<0.01. PAS-GS50: y=-0.077 (SE 0.0269) X+0.0006 (SE 0.00023) X(2)+13.29 (SE 0.552) MSE 1.95, R(2) 0.38, P<0.05. PAS-GRA: y=-0.018 (SE 0.0079) X+13.77 (SE 0.528), MSE 2.28, R(2) 0.24, P<0.05, where y='b' value, x=days post-housing (d96-d216) and MSE=mean square error. Treatment had a significant effect on s.c. adipose tissue β-carotene and lutein (both P<0.001) with PAS-GRA and PH-CON tending to have the highest and lowest concentrations, respectively. PH-CON heifers tended (P=0.058) to have lower LD haem pigments and lighter LD than other heifers. It is concluded that, while concentrate feeding led to the greatest decrease in s.c. adipose tissue yellowness relative to PAS-GRA, choice of dietary ingredients and duration of feeding will depend on the stringency of the colour criteria in particular markets.

An experiment was conducted to establish the effect of feeding either refined coconut oil (CO) or copra meal containing CO to beef heifers on DMI, animal performance, enteric CH4 emissions, diet digestibility, and the fatty acid profile of the resulting meat. Forty-one Charolais and Limousin crossbred beef heifers (474 +/- 29 kg; 661 +/- 89 d of age) were blocked by BW before being assigned in a randomized complete block design to 1 of 3 experimental treatments (n = 12) or to a pretrial slaughter group (n = 5) used to determine the initial carcass weight. The experimental period lasted for 93 d. Enteric CH4 output was recorded for 2 periods of 5 consecutive days from d 14 to 18 and from d 70 to 74. The 3 dietary treatments were 1) control, a barley/soybean meal-based concentrate with 0 g of CO/ d; 2) RCO, a barley/soybean meal-based concentrate with 250 g of CO/d from refined coconut oil; and 3) CM, a copra meal-based concentrate with 250 g of CO/d from copra meal. Each diet had a 50:50 forage:concentrate using grass silage as the forage source. There was no effect of diet on DMI (P = 0.734) or GE intake (P = 0.486). The addition of RCO increased ADG (P < 0.05) compared with the control treatment. The CM treatment decreased (P < 0.05) average daily carcass gain compared with the RCO treatment only. There was a decrease (P < 0.05) in the digestibility of the DM, OM, CP, and GE fractions of the diet only with the CM treatment. Both the RCO and CM concentrates decreased (P < 0.001) daily enteric CH4 output when expressed in terms of liters per day, liters per kilogram of DMI, percentage of GE intake, liters per kilogram of ADG, and liters per kilogram of average daily carcass gain. The RCO treatment produced the greatest numerical response for all measures. Ruminal protozoa numbers on the RCO treatment were lower (P < 0.05) than on the control treatment. The concentrations of the fatty acid methyl esters, lauric (P < 0.001) and myristic (P < 0.002) acids, were increased in muscle when either of the CCO treatments was compared with the controls, but the differences were of a magnitude unlikely to influence human health status. Although the CM concentrate decreased CH4 comparable with the RCO concentrate, decreased performance resulted in an extended finishing time with implications for lifetime CH4 emissions.

The objective was to determine if exercise has a negative impact on the colour stability of beef and if dietary vitamin E (VE) supplementation could counteract any negative effect. Steers were not exercised or were walked 4.41km/day for 18 weeks. Within exercise treatment animals consumed, on average, either 450 or 1050IU/day of VE. Muscle α-tocopherol increased (P=0.004) from 2.35 to 3.15μg/g with VE supplementation. Following ageing M. longissimus dorsi (LD) and M. semimembranosus (SM) steaks were packaged under 80%O(2):20%CO(2) and stored at 4°C. The LD of exercised steers was more red and more saturated (both P<0.05) after 0 and 2 days of storage than LD of unexercised steers. While redness of both muscles decreased over the display period, LD retained a higher redness than SM from day 2 to 7 (P<0.05). Colour shelf-life of LD was extended by 0.75 days, to 3.25 days, due to VE supplementation.

Darker beef from pasture-fed compared with grain-fed cattle may result from differences in physical activity rather than differences in nutrition. The objective was to determine if steers that were exercised produced darker meat than non-exercised steers and whether any effect was muscle-related. Exercised steers were walked 4.41 km daily in a single bout, six days per week for 18 weeks at an average speed of 5.2 kmh(-1). All steers were fed grass silage on an ad libitum basis plus 6 kg concentrates. Following slaughter, muscle colour coordinates ('L' (lightness), 'a' (redness) and 'b' (yellowness) values) of M. longissimus dorsi (LD), M. semimembranosus (SM) and M. extensor carpi radialis (ECR) were recorded at 48 h postmortem and redness and yellowness were used to calculate muscle hue ('H') and colour intensity/saturation ('C'). The pH of all muscles was measured at 1.5, 3, 6, 22 and 48 h postmortem and LD samples were recovered (90 min postmortem) for glycolytic potential (GP) assessment. Exercise did not affect muscle lightness, yellowness, hue or colour intensity. However, LD was the darkest (P<0.001) and SM the most saturated (P<0.001) muscle. Exercise affected muscle redness in a muscle-dependent manner (muscle×exercise, P=0.038) whereby ECR became more red with exercise but LD and SM were unaffected. There were muscle×time (P<0.001) and time×exercise (P=0.045) interactions for muscle pH. The ECR muscle had the highest pH at all times. The exercised steers had higher (P<0.05) LD muscle pH than control steers at 3 and 6 h postmortem. Exercise did not affect myoglobin concentration, which was muscle dependent, decreasing in the order: SM (6.72 mg/g)>ECR (6.33 mg/g)>LD (5.48 mg/g), which were all different (P<0.001). Exercise had no effect on GP in LD muscle (111 vs. 99 μmol/g for control and exercised steers, respectively; SED=6.6 μmol/g). It was concluded that although application of exercise did not affect muscle lightness and thus, did not cause 'darker' meat, it did affect muscle redness in a muscle-dependent manner.

Lipid oxidation and oxymyoglobin oxidation were measured in bovine muscle homogenates. M. longissimus dorsi homogenates (25% w/w, pH 5.7) were prepared, held at 4 degrees C, and subjected to one of the following treatments: (i) stirred and bubbled with oxygen, (ii) stirred with no oxygen, or (iii) neither stirred nor bubbled with oxygen (control). Lipid oxidation was initiated with 45 microM ferric chloride/sodium ascorbate. Lipid oxidation was highest and oxymyoglobin oxidation lowest in the homogenate bubbled with oxygen while lipid oxidation was lowest and oxymyoglobin oxidation highest in the control homogenate. Dissolved oxygen became depleted over time in the control homogenate, remained high in the homogenate bubbled with oxygen, but decreased and then increased in the homogenate stirred with no oxygen. Free radical formation was lower in the control homogenate than in the stirred homogenates as determined by spin trapping and electron spin resonance detection. The data indicated that lipid oxidation-induced oxygen depletion, as opposed to primary or secondary lipid oxidation products, is a likely cause of oxymyoglobin oxidation in muscle systems.

Our objective was to determine the effect of the duration of grazing before slaughter on the fatty acid composition of muscle fat and s.c. adipose tissue (SAT) of beef heifers. Sixty crossbred Charolais heifers (n = 15 per treatment) were assigned randomly to one of four dietary treatments: 45 animals (Treatments 1, 2, and 3, respectively) were housed at the beginning of the experiment, and 15 (Treatment 4) were fed at pasture. Two groups of 15 heifers were moved to pasture 40 d (Treatment 2) and 99 d (Treatment 3) before slaughter, respectively, resulting in preslaughter grazing periods of 0, 40, 99, or 158 d for Treatments 1, 2, 3, and 4, respectively. Before grazing the predominantly perennial ryegrass pasture, animals were housed and offered grass silage ad libitum and 3 kg of concentrate diet (650 g of grass silage/kg of total DMI). After slaughter, the fatty acid profile of the neutral (NL) and polar lipid (PL) fractions of muscle fat from the LM and the total lipids from SAT were analyzed by gas chromatography. Duration of grazing showed a quadratic tendency on mean carcass weight (P = 0.08), but did not affect growth (P = 0.27) or the lipid content (P = 0.13) of the LM. Increasing the duration of grazing led to a linear increase (P < 0.001) in the concentration (on fresh-tissue basis) of CLA in muscle fat (from 11.80 to 17.75 mg/100 g of muscle in NL, and from 0.52 to 0.82 mg/100 of g muscle in PL) and in SAT (from 3.98 to 10.23 mg/g of SAT; P < 0.001), and increased the concentration of C18:1trans-11 in both muscle fat fractions (P < 0.001) and in SAT (P < 0.001). In the total muscle lipids, the polyunsaturated to saturated fatty acid ratio (P:S) increased from 0.12 to 0.15 with increased duration of grazing following a linear (P < 0.05) and cubic pattern (P < 0.05). Increasing the duration of grazing led to a linear decrease in the n-6:n-3 ratio of muscle fat from 2.00 to 1.32 (P < 0.001), and from 2.64 to 1.65 in the SAT lipids (P < 0.001), mainly as a consequence of the increased concentration of C18:3n-3. It is concluded that muscle fat and SAT fatty acid profile was improved from a human health perspective by pasture feeding, and that this improvement depended on the duration of grazing.

Dietary inclusion of polyunsaturated fatty acid (PUFA)-rich plant oils is one approach to improving the fatty acid profile of ruminant meat and meat products from a human health perspective. Whole crop wheat silages represent a possible alternative forage to grass silage for beef production, however, they may adversely impact the fatty acid profile of ruminant muscle since grass silage is rich in C18:3n-3. The first objective of this experiment was to investigate the relationship between an increase in the dietary supply of C18:2n-6 from sunflower oil (SFO) and conjugated linoleic acid (CLA) concentration in the muscle tissue of beef cattle. The second objective was to investigate the effect of the basal forage type on the muscle fatty acid composition and its response to increasing inclusion of SFO. One hundred and five heifers were blocked according to initial bodyweight and assigned to one of seven silage treatments. The silage treatments were: (1) grass silage (GS), (2) whole crop wheat silage with 38% dry matter (DM) (W1), (3) GS and W1 at a ratio of 1:2 (DM basis) (W1GS) (4) GS and W1 at a ratio of 2:1 (DM basis) (GSW1), (5) whole crop wheat silage with 52% DM (W2), (6) GS and W2 at a ratio of 1:2 (DM basis) (W2GS), (7) GS and W2 at a ratio of 2:1 (DM basis) (GSW2). Within each silage treatment, 5 animals were assigned to one of three concentrate rations, differing in the content of SFO. The levels of inclusion of SFO in the concentrate were 0, 55, 110 g/kg concentrate. Inclusion of SFO in the diet led to an increase in the n-6:n-3 fatty acid ratio in muscle. In animals fed grass silage or mixed silages the n-6:n-3 ratio was lower in muscle compared with those fed whole crop wheat silages, with the exception of animals fed 55 g SFO/kg, for which feeding W1GS led to a higher ratio than W1. Other than the n-6:n-3 ratio there were no significant interactions between the effect of type of silage and the level of SFO on the concentration of fatty acids in intramuscular fat. Increasing the inclusion of SFO led to a linear increase in the CLAcis-9,trans-11 and PUFA concentration in intramuscular fat (P<0.001). This study confirmed the potential for modification, and improvement from a human health perspective, of the fatty acid composition of beef muscle by dietary manipulation.

This study investigated the effect of substituting grass silage (C3 photosynthetic plant product) with maize silage (C4 photosynthetic plant product) on the natural abundance carbon (delta13C) and nitrogen (delta15N) stable isotope composition of bovine muscle tissue. Forty-five continental crossbred heifers were assigned to one of three diets consisting of 3 kg of a barley-based concentrate plus grass silage, maize silage or an equal mixture (dry matter basis) of grass silage and maize silage, fed ad libitum, for 167 days. Substitution resulted in less negative delta13C values (P<0.001) in lipid-free muscle and in lipid, and also a lower delta15N (P<0.001) in lipid-free muscle. Feeding of maize silage was clearly reflected in the delta13C of muscle, with each 10% difference in the dietary C4 carbon intake resulting in a 0.9 to 1.0 per thousand shift of delta13C in lipid-free muscle and a 1.0 to 1.2 per thousand in lipid. Minimum detectable mean differences (95% confidence, power 0.80, n=15) in this experiment were about 0.5 per thousand and 1.0 per thousand for delta13C of lipid-free muscle and lipid, respectively, and about 0.5 per thousand for delta15N of lipid-free muscle. The power analysis presented here is useful for estimating minimum isotopic differences that can be detected between any two groups of beef samples with a given number of replicates. It is concluded that carbon stable isotope ratio analysis of meat can be used to quantify C3/C4 dietary constituents in beef production., (Copyright (c) 2005 John Wiley & Sons, Ltd.)

The objectives of this study were (a) to compare muscle and adipose tissue colour of male progeny of two strains of high genetic merit Friesian cows (New Zealand [NZF] and Irish [DAF]) with those of beef (Belgian Blue)×dairy (Holstein-Friesian) [BBHF] male progeny; (b) to compare bulls and steers (gender) of these genotypes and (c) to examine the effects of slaughter weight (SW) on these quality traits. Bulls (n=48) and steers (n=48) of the three genotypes were grown to nominal target liveweights of 550 kg (light) and 630 kg (heavy). Adipose tissue from the NZF genotype was more yellow (P<0.05) than from DAF or BBHF, regardless of gender or SW. For longissimus dorsi (LD) pH, bulls and heavy animals had higher pH (P<0.05) than steers or light animals, respectively, while NZF and BBHF bulls had higher pH than steers. LD muscle from the BBHF genotype had lighter colour (P<0.05) and lower haem pigments (P<0.01) than NZF or DAF progeny. There was no difference in muscle `L' value between light bulls and steers but heavy bulls had darker muscle than heavy steers. There was an interaction between genotype, gender and SW for LD redness. Thus, NZF animals were most red when slaughtered as light or heavy bulls, but there were no differences between genotypes slaughtered as light or heavy steers. These data demonstrate differences in colour of beef, especially from progeny of NZF, which produced the most yellow adipose tissue and the most red muscle tissue.

The effectiveness of organic acids (acetic, citric, lactic) and a citrus juice marinade as tenderising agents in shin beef muscle was investigated. At 0.2 M, citric acid was more effective as a tenderising agent than acetic or lactic acid. Immersion of shin beef strips in citric acid (0-0.05 M) showed that a significant tenderising effect was obtained above a concentration of 0.013 M. When shin beef strips were immersed in the citrus juice marinade (31% orange juice, 31% lemon juice, 38% distilled water) mean pH decreased from 5.7 to 3.1 and mean sample weight increased by ∼65%. The mean Warner-Bratzler shear force value decreased from 178 to 44 N cm(-2) following marination while mean sensory analysis scores for tenderness and juiciness increased following marination. A mean total collagen content of 1.4 g/100 g was recorded in shin beef of which 9% was soluble in unmarinated samples and 29% was soluble in marinated samples. The results indicated that the tenderisation of beef samples using a citrus juice marinade could be attributed to marinade uptake by muscle proteins and also to solubilisation of collagen.

The effects of supplementation of beef cattle diets with organic Se (0.3 mg/kg) and vitamin E (300 I.U. alpha-tocopheryl acetate/kg feed), for 55 d preceding slaughter, on the antioxidant status and oxidative stability of muscle was examined. Dietary vitamin E supplementation led to an increase (P < 0.05) in plasma, and longissimus muscle alpha-tocopherol levels. In minced longissimus muscle stored in 80% 02:20% CO2, lipid and oxymyoglobin oxidation were lower (P < 0.05) in muscle from vitamin E-supplemented animals compared with unsupplemented animals. Dietary Se supplementation did not significantly affect muscle Se levels, glutathione peroxidase activity, or susceptibility to lipid and oxymyoglobin oxidation in the presence or absence of vitamin E. Covariance analysis indicated that, in addition to muscle alpha-tocopherol, differences in muscle glutathione peroxidase activity, and pH could account for variation in the susceptibility of muscle to lipid and oxymyoglobin oxidation.

The objective was to determine, relative to animals expressing their full potential for carcass growth, the impact on meat quality of increasing carcass growth of grazing steers by supplementing with concentrates or by increasing grass supply. Sixty-six continental (Limousin and Charolais) crossbred steers (567 kg) were assigned to one of six diets: (1) 18 kg grass dry matter (DM); (2) 18 kg grass DM grass and 2.5 kg concentrate; (3) 18 kg grass DM and 5 kg concentrate; (4) 6 kg grass DM and 5 kg concentrate; (5) 12 kg grass DM and 2.5 kg concentrate; or (6) concentrates daily. Animals were slaughtered after an average of 95 days. Samples of the M. longissmus dorsi (LD) were collected at the 8-9th rib interface and subjected to sensory analysis and to other assessments of quality following 2, 7, or 14 days aging. Carcass weight gain averaged 360, 631, 727, 617, 551 and 809 g/day for treatments 1 to 6, respectively. There was no difference between diets for colour, Warner-Bratzler shear force (WBSF) or any sensory attribute of the LD. WBSF was negatively correlated with (P<0.05) carcass growth rate (-0.31) but only a small proportion of the variation in meat quality between animals could be attributed to diet pre-slaughter or carcass fatness. It is concluded that high carcass growth can be achieved on a grass-based diet without a deleterious effect on meat quality.

The effects of grazed grass, grass silage, or concentrates on fatty acid composition and conjugated linoleic acid (cis-9, trans-11-18:2; CLA) concentrations of i.m. fat of steers fed to achieve similar carcass growth rates were investigated. Fifty steers were divided into 10 blocks based on body weight and assigned at random from within blocks to one of five dietary treatments. The experimental rations offered daily for 85 d preceding slaughter were 1) grass silage for ad libitum intake plus 4 kg of concentrate, 2) 8 kg of concentrate plus 1 kg of hay, 3) 6 kg of grazed grass DM plus 5 kg of concentrate, 4) 12 kg of grazed grass DM plus 2.5 kg concentrate, or 5) 22 kg of grazed grass DM. The concentration of polyunsaturated fatty acids (PUFA) in i.m. fat was higher (P < .05) for steers offered ration 5 than for those given any other ration. Decreasing the proportion of concentrate in the diet, which effectively increased grass intake, caused a linear decrease in the concentration of i.m. saturated fatty acids (SFA) (P < .01) and in the n-6:n-3 PUFA ratio (P < .001) and a linear increase in the PUFA:SFA ratio (P < .01) and the conjugated linoleic acid concentration (P < .001). The data indicate that i.m. fatty acid composition of beef can be improved from a human health perspective by inclusion of grass in the diet.

The objective of this experiment was to determine the effect of varying the proportions of autumn grass and concentrates and grass silage and concentrates on the quality of meat from cattle with similar rates of carcass growth. Fifty continental crossbred steers were assigned to five treatments. The experimental diets offered were (1) grass silage ad libitum plus 4 kg concentrate (SC), (2) 1 kg hay plus 8 kg concentrate (CO), (3) 6 kg grass dry matter (DM) plus 5 kg concentrate (CG), (4) 12 kg grass DM plus 2.5 kg concentrate (GC) and (5) 22 kg grass DM (GO). The experiment lasted 85 days after which all animals were slaughtered. The right side m. longissmus dorsi was excised from all animals 24 h post slaughter for assessment of meat quality. Treatments SC and CO resulted in animals with whiter (P<0.05) subcutaneous and kidney/channel fat than all other treatments. There was an interaction (P<0.05) between ageing time and treatment with treatment GC having higher (P<0.05) tenderness, texture and acceptability values after 2 days ageing, but not after 7 or 14 days ageing. It is concluded that supplementing grass with low levels of concentrate produced the most tender and acceptable meat at 2 days post mortem, but that further ageing eliminated all treatment effects on eating quality of beef.

The effect of oxygen level (20, 40, 60 and 80%) in modified atmospheres on the oxymyoglobin content of intact and minced beef (M. semimembranosus, SM) was evaluated. There was no significant difference in the oxymyoglobin content of minced SM stored for up to 4 days in modified atmosphere packs containing 20, 40, 60 or 80% O(2). After 7 days, oxymyoglobin in minced SM decreased significantly (P⩽0.05) with decreasing oxygen level but by day 10 all samples had similarly low oxymyoglobin contents. Lipid oxidation increased significantly (P⩽0.05) between day 7 and 10 of storage in minced SM stored in modified atmospheres containing 40, 60 or 80% O(2). Oxymyoglobin and lipid oxidation occurred in intact SM but the extent of oxidation was lower than for minced SM. Exogenous α-tocopherol, dispersed in olive oil and added to minced SM (300 and 3000 mg α-tocopherol/kg lipid), had no significant effect on Hunter 'a' values when the samples were stored in low (20%) or high (80%) oxygen atmospheres. Exogenous α-tocopherol addition led to a significant reduction in lipid oxidation (P⩽0.05) in minced SM stored in high but not in low oxygen atmospheres.

Minced beef samples stored in high oxygen modified atmosphere packs (80% O(2):20% CO(2)) were evaluated for colour stability during refrigerated storage. The oxymyoglobin content and surface redness (Hunter 'a' value) of m. biceps femoris samples, previously frozen and minced, were significantly lower in samples with a mean vitamin E (α-tocopherol) content of 2.5 μg g(-1) compared with samples with 3.3, 3.9 or 5.5 μg g(-1) after 4, 6 and 8 days of storage at 4 °C. Lipid oxidation was significantly higher in the beef samples with the low vitamin E content compared with the other groups indicating that a likely mechanism for the colour-stabilising effect of vitamin E is through its action as a lipid antioxidant., (Copyright © 1998. Published by Elsevier Ltd.)

The effects of protein polymerization in whey protein isolate-stabilized emulsions on emulsion properties were investigated. Polymerization, involving intermolecular disulfide bonds between whey proteins adsorbed at the oil-water interface, increased with increasing storage time following emulsion formation. Ageing resulted in increased aggregation of emulsion droplets, emulsion viscosity and susceptibility to creaming but these effects were lower when thiol-disulfide interchange reactions were inhibited by N-ethylmaleimide (NEM). Following heating to 75 degrees C, disulfide-mediated polymerization of whey proteins increased as did droplet aggregation, emulsion viscosity and creaming. While NEM lowered the extent of disulfide-mediated polymerization it did not affect the measured physical properties of the heated emulsions. Non-covalent interactions appeared to be the principal forces leading to aggregation of emulsion droplets but aggregates once formed were stabilized by disulfide bonds.

The effect of oxidized corn oil and vitamin E (α-tocopheryl acetate) in pig diets on the oxidative stability of muscle lipids and on the surface colour characteristics of fresh and previously frozen pork chops in refrigerated storage was investigated. Lipid oxidation (TBARS values) and surface redness (Hunter 'a' values) were significantly influenced (P < 0·01) by dietary α-tocopheryl acetate levels but not by degree of oxidation of dietary corn oil. Lipid oxidation and colour deterioration during refrigerated storage were greater in previously frozen chops compared to fresh chops. TBARS values were lower and Hunter 'a' values higher in pork chops from pigs fed 100 and 200 mg α-tocopheryl acetate/kg diet compared to pigs fed 10 mg/kg diet after 2, 4, 6 and 8 days of refrigerated storage. Hunter 'a' values were significantly correlated (P < 0·01) with the logarithm of TBARS values. The results suggest that oxidation of myoglobin precedes oxidation of muscle lipids in pork chops stored at 4°C., (Copyright © 1994. Published by Elsevier Ltd.)

The catalytic effect of haem proteins (haemoglobin and myoglobin) and inorganic iron (FeSO(4)) on lipid oxidation in a muscle model system was investigated. Haem proteins had a greater prooxidant effect than inorganic iron in raw and heated pork muscle residue when these prooxidants were present at levels approaching those in red meats. The rate of lipid oxidation catalysed by each prooxidant increased as the iron concentration increased over a range of 1-17 μg/g muscle residue. The relative prooxidant effects of haem protein and inorganic iron were not affected by the mode of addition of the prooxidants to the muscle residue (addition in a concentrated form or dispersed in water), or by the method of cooking (fast versus slow cooking)., (Copyright © 1993. Published by Elsevier Ltd.)

Sixty-four pigs, approximately 3 weeks old, were fed diets containing 3% beef tallow or 3% soya oil with either a basal (10-50 mg/kg diet) or supplemented (200 mg/kg diet) level of α-tocopheral acetate. In pigs fed the soya oil diet the neutral and polar lipid fractions of muscle tissue and the total lipid fraction of adipose tissue had significantly (P < 0·05) higher C18:2/C18:1 ratios when compared to pigs fed the tallow diet. Muscle from pigs fed the soya oil diet was significantly more susceptible (P < 0·05) to lipid oxidation than muscle from pigs fed the tallow diet. In pigs receiving the α-tocopherol supplemented diet, α-tocopherol levels were approximately 3·3, 2·8 and 2-times higher in plasma, muscle and adipose tissue, respectively, when compared to pigs fed the basal level of α-tocopherol acetate. α-Tocopherol supplementation significantly increased (P < 0·05) the oxidative stability of muscle from pigs fed both the tallow and soya oil diets., (Copyright © 1991. Published by Elsevier Ltd.)

Experiments were designed to investigate the effects of dietary α-tocopherol supplementation for 2 weeks prior to slaughter on plasma and muscle α-tocopherol levels and on the oxidative stability of raw and cooked pig muscle during refrigerated storage at 4°C. Plasma and muscle α-tocopherol levels of the pigs on the α-tocopherol supplemented diet (200 mg α-tocopherol acetate/kg feed) were ∼2·5-fold higher than those of the pigs on the control diet (30 mg α-tocopherol acetate/kg feed). Dietary supplementation with α-tocopherol significantly (p < 0·01) improved the oxidative stability of both raw and cooked muscle after storage at 4°C for up to 8 days. α-Tocopherol stabilized the membrane-bound lipids against metmyoglobin/H(2)O(2)-initiated oxidation and also significantly (p < 0·05) improved the oxidative stability of rendered fat., (Copyright © 1990. Published by Elsevier Ltd.)