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Context Different cereal grain sources may be used in beef production but little is known about their effects on beef quality. Aims This study evaluated fatty acid composition, α-tocopherol concentration and oxidative stability of beef from bulls fed barley or a combination of barley and either ground or toasted flaked maize. Methods Fatty acid composition, α-tocopherol concentration, lipid oxidation and colour stability were measured in beef from late maturing bulls finished on a barley-based concentrate (BC) or on the concentrate with barley partially replaced by either maize meal (MM) or flaked meal (FM). Samples of M. longissimus thoracis were subjected to simulated retail display (4°C) for 3, 7, 10 and 14 days in modified atmosphere packs (O2:CO2; 80:20). Muscle was analysed for fatty acid and α-tocopherol concentrations, colour stability and lipid oxidation. Key results There were differences in the fatty acid concentrations. Total fatty acids, monounsaturated fatty acids and saturated fatty acids were higher (P 0.05) in colour stability of muscle due to dietary treatment. Conclusions Partial replacement of barley with maize in the diet of bulls influences muscle fatty acid concentration and profile, leading to a marginal increase in lipid oxidation with no detrimental effect on colour stability. Implications Toasted-flaked or ground maize may partially substitute for rolled barley in a concentrate ration without affecting colour stability of meat under retail display conditions. The slight increase in lipid oxidation, after prolonged storage, in beef from bulls fed flaked toasted maize is unlikely to be of significance from a product acceptability perspective.

The influence of modifying a traditional 24-mo dairy steer calf to beef production system on the fatty acid composition of the longissimus muscle and its potential to authenticate beef provenance was examined. Fifty-four male calves (n = 18 per sire breed), progeny of Holstein-Friesian cows mated with Holstein-Friesian (HF), Aberdeen Angus (AA) and Belgian Blue (BB) bulls were at pasture from March until August of their second year when they were assigned to a 3 (breed types) × 3 (finishing strategies) factorial experiment. The three finishing strategies were (i) pasture only for a further 94 d prior to slaughter (21 mo of age) (Grass), (ii) concentrates ad libitum indoors for 94 d prior to slaughter (21 mo of age) (EC) and (iii) pasture only for a further 94 d followed by concentrates ad libitum indoors for 98 d prior to slaughter (24 mo of age) (LC). Compared to EC, muscle from Grass had a lower intramuscular fat concentration and omega-6: omega-3 polyunsaturated fatty acid (PUFA) ratio and higher proportion of conjugated linoleic acid. A longer period at pasture pre-concentrate finishing increased the concentration of omega-3 PUFA which was still lower than in Grass. To maximise the omega-3 PUFA concentration, a late-maturing breed is more appropriate while to maximise conjugated linoleic acid, an early-maturing breed is more appropriate and both should be finished on grass. Chemometric analysis confirmed that the fatty acid profile can authenticate “Grass-Finished” beef per se and has potential to distinguish “Concentrate-Finished” beef based on the length of grazing prior to finishing, but not distinguish between sire breeds.

There is a requirement in some beef markets to slaughter bulls at under 16 months of age. This requires high levels of concentrate feeding. Increasing the slaughter age of bulls to 19 months facilitates the inclusion of a grazing period, thereby decreasing the cost of production. Recent data indicate few quality differences in longissimus thoracis (LT) muscle from conventionally reared 16-month bulls and 19-month-old bulls that had a grazing period prior to finishing on concentrates. The aim of the present study was to expand this observation to additional commercially important muscles/cuts. The production systems selected were concentrates offered ad libitum and slaughter at under 16 months of age (16-C) or at 19 months of age (19-CC) to examine the effect of age per se, and the cheaper alternative for 19-month bulls described above (19-GC). The results indicate that muscles from 19-CC were more red, had more intramuscular fat and higher cook loss than those from 16-C. No differences in muscle objective texture or sensory texture and acceptability were found between treatments. The expected differences in composition and quality between the muscles were generally consistent across the production systems examined. Therefore, for the type of animal and range of ages investigated, the effect of the production system on LT quality was generally representative of the effect on the other muscles analysed. In addition, the data do not support the under 16- month age restriction, based on meat acceptability, in commercial suckler bull production.

Finishing late-maturing bulls on grass may alter the antioxidant/prooxidant balance leading to beef with higher susceptibility to lipid oxidation and a lower colour stability compared to bulls finished on cereal concentrates. In this context, lipid oxidation and colour stability of beef from late-maturing bulls finished on pasture, with or without concentrate supplements, or indoors on concentrate was assessed. Charolais or Limousin sired bulls (n = 48) were assigned to four production systems: (1) pasture only (P), (2) pasture plus 25% dietary DM intake as barley-based concentrate (PC25), (3) pasture plus 50% dietary DM intake as barley-based concentrate (PC50) or (4) a barley-based concentrate ration (C). Following slaughter and postmortem ageing, M. Longissimus thoracis et lumborum was subjected to simulated retail display (4°C, 1000 lux for 12 h out of 24 h) for 3, 7, 10 and 14 days in modified atmosphere packs (O2 : CO2; 80 : 20). Lipid oxidation was determined using the 2-thiobarbituric acid-reactive substances assay; α-tocopherol was determined by HPLC; fatty acid methyl esters were determined using Gas Chromatography. Using a randomised complete block design, treatment means were compared by either ANOVA or repeated measures ANOVA using the MIXED procedure of SAS. Total polyunsaturated fatty acid (PUFA) concentrations were not affected by treatment, n-3 PUFAs were higher (P < 0.001) and the ratio of n-6 to n-3 PUFAs was lower (P < 0.001) in muscle from P, PC25 and PC50 compared to C. α-Tocopherol concentration was higher in muscle from P compared to PC50 and C bulls (P = 0.001) and decreased (P < 0.001) in all samples by day 14. Lipid oxidation was higher in muscle from C compared to P bulls on day 10 and day 14 of storage (P < 0.01). Finishing on pasture without supplementation did not affect beef colour stability and led to lower lipid oxidation, possibly due to the higher α-tocopherol concentration compared to concentrate finished beef.

This study was commissioned to assess if there are regional differences in the acceptability of beef between consumers from Northern Ireland (NI), Republic of Ireland (ROI) and Great Britain (GB). Palatability traits were affected by socioeconomic and behavioural factors such as preferred cooking endpoint, animal welfare, value, health aspects of beef product, ease of preparation as well as consumption frequency for specific cuts. "Willingness to pay" (WTP) was influenced by income, preferred cooking endpoint, value of beef product, ease of preparation and consumption frequency for frying steak. Results showed that GB consumers scored higher for the same striploin steak compared to NI and ROI consumers. This may be due to differences in the motivation for beef choice and/or consumption habits. GB consumers were less concerned about the healthiness of beef product and beef origin. In addition, a higher consumption frequency for rump was reported in GB, which may explain the higher sensory scores observed among GB consumers for striploins.

Demand for beef produced from pasture-based diets is rising as it is perceived to be healthier, animal friendly and good for the environment. Animals reared on a solely grass forage diet, however, have a lower growth rate than cereal-fed animals and consequently are slaughtered at an older age. This study focused on the former by conducting life cycle assessments of beef production systems offering only fresh or conserved grass, and comparing them to a conventional pasture-based beef production system offering concentrate feeding during housing. The four suckler weanling-to-beef production systems simulated were: (i) Steers produced to slaughter entirely on a grass forage diet at 20 months (GO-20); (ii) Steers produced to slaughter entirely on a grass forage diet at 24 months (GO-24); (iii) Steers produced to slaughter on a grass forage diet with concentrate supplementation during housing (GC-24), and (iv) Steers produced to slaughter entirely on a grass forage diet at 28 months (GO-28). Two breed types were evaluated: early-maturing and late-maturing (LM). The environmental impacts assessed were global warming potential (GWP), non-renewable energy (NRE), acidification potential (AP), eutrophication potential (marine (MEP) and freshwater) were expressed per animal, per kg live weight gain (LWG), kg carcass weight gain, and kg meat weight gain (MWG). The GO-20 production system had the lowest environmental impact across all categories and functional units for both breeds. Extending age at slaughter increased environmental impact across all categories per animal. The LWG response of EM steers to concentrate feed supplementation in GC-24 was greater than the increase in total environmental impact resulting in GC-24 having a lower environmental impact across categories per kg product than GO-24. Concentrate feed supplementation had a similar effect on LM steers with the exception of NRE and AP. The increase in daily LWG in the third grazing season in comparison to the second grazing and housing resulted in GO-28 having lower GWP, NRE, AP, and MEP per kg product than GO-24. Early-maturing steers had lower environmental impact than LM when expressed per kg LWG. However the opposite occurred when impacts were expressed per kg MWG, despite LM steers producing the least LWG. The LM steers compensated for poor LWG performance by having superior carcass traits, which caused the breed to have the lowest environmental impact per kg MWG. The results reaffirms the importance of functional unit and suggests reducing the environmental impact of LWG does not always translate into improvements in the environmental performance of meat.

Meeting the food demands of a growing global population within planetary boundaries is a challenge. Sustainably producing animal-sourced foods while supplying sufficient protein to meet the requirements of a healthy diet is a particular challenge. This paper informs the development of pathways to sustainable animal production by examining trends in animal-sourced foods since 2000, including the significance of animal- relative to plant-protein sources. Drawing on three distinct scenarios defined by the Food and Agriculture Organization (FAO), (i.e. Business As Usual (BAU), a continuation of historical trends of food preferences including initiatives to address Sustainable Development Goal targets; Stratified Societies (SSs), leaving challenges unattended; and Towards Sustainability (TS); a more equitable global society and more sustainable food system due to effective polices), future demand for animal-sourced foods is projected. Analysis is based on FAO Food Balance Sheet data (2000–2017) and projected national protein demand per capita (2012–2050). Analysis is disaggregated to five global regions defined by the World Health Organization. It finds that patterns of past demand for animal-sourced foods vary by food (e.g. red vs white meat) and region. However, the European region consistently has the highest levels of consumption of animal-sourced foods, while the South-East Asian and African regions have the lowest. The ratio of animal to plant-sourced protein varies across regions, ranging from 0.29 in Africa to 1.08 in Europe in 2017. Over time, the ratio is relatively stable or moderately increasing, driven by rising incomes in low- or middle-income countries. Under the future scenarios, all World Health Organization regions show a marked increase in demand for animal-sourced protein across BAU and SS. The TS scenario, however, projects notable declines in consumption across Europe and the Americas when compared to the 2012 BAU baseline, with a decline in milk also in the Western Pacific. In contrast, meat and milk consumption in Africa and South-East Asia is projected to increase, reflecting their far lower starting consumption levels. The analysis and subsequent discussion highlight the importance of having regional-specific strategies to deal with the challenge of sustainable livestock production and consumption, with a requirement to consider the impact of actions in one region on others. Clearly, the challenge is not merely one for science and technology but one based on wider aspects of the food system and its diverse stakeholders.

8 páginas, 6 tablas., The hypothesis that inclusion of a rumen-inert fat in the diet of dairy-origin bulls would enhance EUROP carcass fat classification and tissue fatty acid composition was tested. Sixty bulls (age = 508 days, s.d. 29.1) were offered ad libitum, a barley-based concentrate ration that contained 0, (control) 26 (MEGA1) or 81 g (MEGA2) calcium salts of palm oil fatty acids (Megalac)/kg such that the rations contained 25, 49 and 116 g acid-hydrolysed ether extract /kg dry matter (DM), respectively. Intake (per pen of 5 bulls), live weight and ultrasonic backfat thickness were measured during a 130 day feeding period after which bulls were slaughtered, carcass characteristics recorded and a sample of longissimus muscle (LT) and subcutaneous adipose tissue (SAT) collected for fatty acid analysis. Subcutaneous fat depth was similar for control and MEGA1 bulls but lower (P < 0.05) for MEGA2 bulls after 60 days of the study. After 125 days, compared to control bulls subcutaneous fat depth was higher for MEGA1 bulls but lower for MEGA 2 bulls (P < 0.05). Carcass gain tended (P = 0.074) to be lower for MEGA2 bulls compared to control and MEGA1 bulls, which reflected their lower consumption of concentrate DM and metabolisable energy (ME) but the efficiency with which consumed DM or ME was converted to live or carcass weight did not differ significantly between rations. There was no difference between control and MEGA1 bulls for any measurement of carcass fatness. Compared to control and MEGA1 bulls, carcasses from MEGA2 bulls were lighter, had a lower depth of fat covering the LT muscle measured post-mortem (P < 0.05) and a numerically lower carcass fat classification. There were only minor effects of ration composition on the fatty acid profile of LT or SAT. With regard to nutritional indices in meat, compared to control bulls, inclusion of Megalac did not affect the polyunsaturated (P) to saturated fatty acid ratio or the n-6 to n-3 P ratio of tissue lipids. It is concluded that for the type of animal and feeding arrangement in this study, rumen inert fat inclusion was not an effective strategy to enhance carcass fat classification or the nutritional value of beef., This study was supported from within Teagasc core funding.

In bulls, with a genetic predisposition for leanness and reared in a grass-based production system dietary fish oil may further enhance the nutritional value of beef by increasing the concentration of the omega 3 polyunsaturated fatty acids (PUFA) eicosapentanoic acid (EPA) and docosahexanoic acid (DHA). The impact of including rumen protected fish oil in the finishing diet of late maturing breed bulls on their growth, feed efficiency, carcass fat classification, aspects of ultimate meat quality and the fatty acid composition of the M. Longissimus thoracis muscle (LT) was examined. Twelve month old bulls were supplemented with a barley-based concentrate (500g/kg dietary dry matter) from turn-out to pasture in spring until housing 94 days later. Bulls were housed indoors and offered ad libitum, either the same concentrate or a concentrate containing rumen protected fish oil (PFO) at a ration fat concentration of 50g/kg dry matter, along with grass silage to appetite, for 88 days pre-slaughter. Inclusion of PFO increased (P

This study aimed to examine the effects of replacing rolled barley (high in starch) with citrus pulp (high in digestible fibre) in a supplement on intake and performance of young growing cattle offered grass silage ad libitum for 101 days. Weaned, early- and late-maturing breed, male suckled beef calves (n=120) were blocked by sire breed, gender and weight and from within block randomly assigned to one of two concentrate supplements based mainly on rolled barley (BAR) or citrus pulp (CIT) and formulated to have similar concentrations of true protein digestible in the small intestine. On day 87, blood samples were taken before and 2 h after feeding, and rumen fluid samples were collected 2 h post-feeding. Supplement type did not affect (P>0.05) grass silage intake, live weight gain, final live weight, ultrasonically assessed body composition or measurements of skeletal size. Rumen pH (6.64 v. 6.79), ammonia (51 v. 81 mg/l) and acetate-to-propionate ratio (2.7 v. 3.2) were lower (P

This experiment aimed to assess the effect of different indoor winter growth rates (WGR) followed by different concentrate supplementation levels at pasture on meat quality of 90 bulls. During the first winter, bulls were offered grass silage ad libitum and either 3 kg (WGR3) or 6 kg (WGR6) of concentrates. After turn-out to pasture, bulls were offered: grass without supplementation (PO), grass plus 0.2 predicted dry matter intake (DMI) as concentrates (PL) or grass plus 0.4 predicted DMI as concentrates (PH). After finishing, colour, chemical composition (unaged), instrumental texture and sensory characteristics (14 days of ageing) of longissimus thoracis were measured. WGR6 bulls had heavier carcasses than WGR3 bulls. There was an interaction between WGR and supplementation for instrumental texture and redness (a). Within WGR3, PO beef was the most tender, whereas within WRG6, PL was the most tender. However, these differences were not detected by the sensory panel. Within WGR3, redness was the lowest for PL, whereas within WRG6, PO was the least red. No differences were found for chemical composition. The multivariate analysis highlighted WGR as the main variable affecting meat quality characteristics. In conclusion, variations in growth path exerted minor effects on appearance and instrumental texture which did not affect the perception of bull beef by a trained sensory panel.

This study aimed to compare the quality of beef from suckler bulls raised on a high-energy concentrate ration and slaughtered at different carcass weights (CW)/ages. In total, 42 spring-born, Charolais and Limousin-sired, weaned suckler bulls were provided with a finishing diet of ad libitum concentrates and grass silage until they reached target CW of 340, 380 and 420 kg. Intramuscular fat (IMF) content tended ( P P P P

The performance of early-maturing breed sired suckler bulls finished at pasture, with or without concentrate supplementation, at 15 or 19 months of age was evaluated. In total, 60 Aberdeen Angus-sired bulls were assigned to a two (slaughter age (SA): 15 (S15) or 19 (S19) months)×two (finishing strategies (FS): grass only or grass+barley-based concentrate) factorial arrangement. There were no (P>0.05) SA×FS interactions. Increasing SA increased carcass weight (265 v. 355 kg), kill-out proportion (542 v. 561 g/kg), conformation (6.7 v. 8.3, 1 to 15) (P

The proximate composition, fatty acid (FA) profile and antioxidant capacity of beef from steers fed varying inclusion levels of dried corn gluten feed (CGF) were examined. Forty-eight Charolais and Limousin-sired steers (424.0 ± 39.0 kg), blocked by breed and body weight, were randomly assigned to one of four concentrate rations (n = 12 steers/treatment, 4.0 kg dry matter basis daily) offered as a supplement to grass silage fed ad libitum for 124 days pre-slaughter. Concentrate rations contained either 0% CGF (control, barley/soybean meal-based ration), 25% CGF, 50% CGF or 75% CGF. Following slaughter, longissimus thoracis muscles (LT) were excised at 48 h post-mortem, vacuum packaged and aged for 14 days prior to further analysis. Diets containing 25% and 75% CGF increased the pH (~ 5.47 to 5.53) of LT compared to control whereas 50% CGF decreased the protein content and increased intramuscular fat of LT compared to 25% CGF. In comparison to the control, 25% and 75% CGF decreased C14:0 and increased long-chain polyunsaturated FA (PUFA, C22:2 n-6 and C20:5 n-3) and total n-3 PUFA (P < 0.01) whereas 75% CGF increased (P< 0.05) conjugated linoleic acids (c-9 t-11+t-9 c-11 18:2) and α-linolenic acid. No treatment effect on the antioxidant status (α-tocopherol content, radical scavenging and iron-chelating activities) of LT was observed. However, the total phenol content and iron-reducing antioxidant power in LT followed the order: control > 50% CGF (P < 0.05) and 25% CGF > control = 50% CGF (P < 0.01), respectively. Lipid and oxymyoglobin oxidation were unaffected by dietary treatment when muscle homogenates were subjected to iron/ascorbate-induced oxidation for up to 4 h at 4 ºC. Overall, results demonstrated that replacement of barley/soybean meal with up to 75% CGF in supplementary concentrate diets of steers increased health-promoting unsaturated FA in beef without negatively influencing the susceptibility of beef to oxidative deterioration.

Beef cattle partition dietary nitrogen (N) into tissues or excrete it in feces and urine, which contributes significantly to water and air pollution. The objectives were to examine the effects of supplementing fresh grass herbage with a low crude-protein, high-energy supplement - citrus pulp - on intake, digestion and N-balance in beef cattle. Sixteen Charolais steers (live weight 585 kg, S.D. 24.1) were used in a randomized block design experiment. Treatments consisted of either unsupplemented zero-grazed grass (predominantly Lolium perenne) harvested 21-d after it received 50 kg N/ha, offered ad libitum (GO), or the same grass supplemented with 2.25 kg citrus pulp DM daily (GS). Following a 21-d dietary adaptation phase, animals were accommodated in metabolism stalls for 10 d (2-d adaptation: 8-d sampling). During this period grass and citrus pulp was offered at 0.85 of the pre-determined daily DM intake; the grass: supplement ratio for GS remained the same as during the adaptation phase. Grass was offered in two equal meals and citrus pulp in one morning meal. Total faeces and urine were collected on a 48-h and 24-h basis, respectively. Data were analysed using AVOVA with terms for treatment and block in the model. Supplementation decreased (P0.05) between treatments. Total N and urinary N excretion were 15 and 23 g/d lower, respectively, and faecal N excretion was 9 g/d greater for GS compared to GO (P0.05). The quantity of N retained and, therefore, N-use efficiency did not differ (P>0.05) between treatments (33 vs. 28 %). Supplementing grass herbage with a low-protein, high-energy feed may be a strategy to reduce total and urinary N excretion in grazing beef cattle.

RATIONALE Hair keratin is a very important material in ecological and archaeological studies because it grows continuously, can be obtained non-invasively, does not require extensive processing prior to analysis and can be found in archaeological sites. Only a few studies have examined seasonal variations in hair isotope values, and there is no published dataset examining the isotope variability recorded in the keratinous tissues of stationary (i.e., non-migrating) domestic mammals. METHODS Thirty-six Irish sheep were sampled in eight farms every three months between September 2006 and June 2007. A shearing strategy was adopted to sample only the most recently grown wool in order to represent an average of the summer, autumn, winter and spring conditions. The stable isotope ratios of the ground samples were measured using two different stable isotope mass spectrometers operated in dual-inlet (C, N) and continuous-flow (O, H) mode. RESULTS Wool O isotope ratios are a good proxy for seasonal variability in climate and can be used to anchor a chronology independently of other isotope records (C, N) that are influenced by diet or physiology. By contrast, interpretation of seasonal variations in hair H isotope composition in terms of climate is more complex probably due to the influence of dietary H. The C and N isotope values of grass-fed animals varied seasonally, probably reflecting the annual cycle of seasonal variation in grass isotope values. The highest δ(13) C values were measured in summer-grown wool, while the highest δ(15) N values were measured in winter-grown wool. Supplementation of the sheep diet with concentrates was detected easily and was marked by an increase in δ(13) C values and a decrease in δ(15) N values in winter-grown wool. CONCLUSIONS The present study demonstrates that time-resolved sampling and stable isotope ratio analysis of sheep wool can be used to identify short-term changes in diet and climate and therefore offer a tool to examine a wide variety of present and past husbandry practices.

The Norwegian Red and Jersey dairy breeds have been evaluated for crossbreeding with Holstein–Friesian dairy cows in Ireland. If such crossbreeding becomes common practice, the resultant male calves will enter the beef industry. The objective was to compare production and carcass traits for Holstein–Friesian (HF), Norwegian Red×Holstein–Friesian (NR) and Jersey×Holstein–Friesian (JE) male cattle. A total of 120 spring-born male calves were reared to slaughter in a 3 breed types (HF, NR and JE)×two genders (bulls and steers)×2 slaughter weights (Light, 570 kg and Heavy, 640 kg) factorial experiment. Following rearing indoors, the calves were at pasture for the first grazing season. Steers were castrated in September. The calves were housed for the first winter in October and offered grass silage ad libitum plus 1.5 kg/day concentrates. They returned to pasture in April for their second grazing season. The bulls were housed in August and the steers were housed in November. Both genders were finished on a total mixed ration of proportionately 0.67 concentrates and 0.33 silage (dry matter basis). Routine slaughter data were collected. The ribs joint was dissected into its components. Across gender and slaughter weight groups, slaughter weights per day of age were 836, 828 and 761 (s.e. 12.2) g for HF, NR and JE, respectively. Corresponding carcass weights and kill-out proportions were 314, 309 and 277 (s.e. 5.2) kg, and 495, 499 and 485 (s.e. 2.9) g/kg, respectively. Carcass conformation class (15-point scale) was 4.7, 5.3 and 4.0 (s.e. 0.23) for HF, NR and JE, respectively. Carcass fat class (15-point scale) was 8.5, 8.6 and 7.7 (s.e. 0.26) for HF, NR and JE, respectively. Feed intake during finishing was similar for the breed types, but intake per kg mean live weight was higher for JE. Slaughter weight per day of age was greater for bulls than steers and for Heavy than Light slaughter weight. Bulls had higher kill out proportions, better carcass conformation, greater M. longissimus area and a greater proportion of ribs joint muscle, and a lower proportion of fat than steers. There were few important interactions. It is concluded that crossbreeding with NR had no negative effects on the beef merit of the male progeny compared with pure Holstein–Friesian but crossbreeding with JE reduced carcass weight and value per kg.

10 páginas, 2 tablas., Growth in demand for foods with potentially beneficial effects on consumer health has motivated increased interest in developing strategies for improving the nutritional quality of ruminant-derived products. Manipulation of the rumen environment offers the opportunity to modify the lipid composition of milk and meat by changing the availability of fatty acids (FA) for mammary and intramuscular lipid uptake. Dietary supplementation with marine lipids, plant secondary compounds and direct-fed microbials has shown promising results. In this review, we have compiled information about their effects on the concentration of putative desirable FA (e.g. c9t11-CLA and vaccenic, oleic, linoleic and linolenic acids) in ruminal digesta, milk and intramuscular fat. Marine lipids rich in very long-chain n-3 polyunsaturated fatty acids (PUFA) efficiently inhibit the last step of C18 FA biohydrogenation (BH) in the bovine, ovine and caprine, increasing the outflow of t11-18:1 from the rumen and improving the concentration of c9t11-CLA in the final products, but increments in t10-18:1 are also often found due to shifts toward alternative BH pathways. Direct-fed microbials appear to favourably modify rumen lipid metabolism but information is still very limited, whereas a wide variety of plant secondary compounds, including tannins, polyphenol oxidase, essential oils, oxygenated FA and saponins, has been examined with varying success. For example, the effectiveness of tannins and essential oils is as yet controversial, with some studies showing no effects and others a positive impact on inhibiting the first step of BH of PUFA or, less commonly, the final step. Further investigation is required to unravel the causes of inconsistent results, which may be due to the diversity in active components, ruminant species, dosage, basal diet composition and time on treatments. Likewise, research must continue to address ways to mitigate negative side-effects of some supplements on animal performance (particularly, milk fat depression) and product quality (e.g. altered oxidative stability and shelf-life)., This work was conducted within the framework of the research projects AGL2014-54587 and AGL2017-87812 (Spanish Ministry of Economy and Competitiveness, MINECO). P.G.T. benefited from a Ramón y Cajal research contract (RYC-2015-17230, MINECO).

Context The finishing of late-maturing bulls on grass is economically more favourable than finishing on cereal concentrates but it may have a negative effect on oxidative stability. Aim To determine the effect of varying levels of pasture feeding during the finishing period on the oxidative stability of bull beef. Methods Groups of eight late-maturing breed sired bulls were assigned to one of the following production systems: (1) pasture only for 200 days (P), (2) pasture only for 100 days followed by pasture plus 50% of the dietary dry matter (DM) intake as concentrate for 100 days (P-C50), (3) pasture plus 50% of the DM intake as concentrate for 200 days (C50), (4) pasture only for 100 days followed by ad libitum concentrates for 100 days (P-C), (5) pasture plus 50% of the DM intake as concentrate for 100 days followed by ad libitum concentrates for 100 days (C50-C) and (6) ad libitum concentrates offered indoors for 200 days (C). The M. Longissimus thoracis et lumborum muscle was excised post-slaughter for proximate, fatty acid and α-tocopherol analysis and for measurement of lipid and protein oxidation and colour stability. Results The polyunsaturated fatty acid (PUFA) concentration and proportion in muscle were higher (P < 0.001) in C50 bulls compared with P, P-C50 and P-C bulls. The concentration of highly peroxidisable PUFA was at least 1.3-fold higher (P < 0.001) in the muscle of C50 bulls than of C and P-C bulls whereas the proportion was at least 1.5-fold higher (P < 0.001) in muscle of P, P-C50 and C50 bulls compared with C and P-C bulls. There was a higher (P < 0.001) concentration of saturated fatty acids and monounsaturated fatty acids in muscle of bulls fed on concentrate in the last 100 days (P-C, C50-C and C) compared with those fed on grass (fully or partially) in the last 100 days (P, P-C50 and C50). α-Tocopherol concentration was at least 1.5-fold higher (P < 0.001) in muscle of P bulls compared with C, C50-C and P-C bulls. Redness, redness stability, lipid and protein oxidation did not differ between treatments (P > 0.05). Conclusions The increase in highly peroxidisable PUFA in beef, by increasing pasture in the finishing ration did not increase susceptibility to oxidation, most likely due to a concomitant increase in α-tocopherol. Implications Beef can be produced from late-maturing bulls grazing on pasture for 200 days without impacting negatively on oxidative stability.

Serial sampling and stable isotope analysis performed along the growth axis of vertebrate tooth enamel records differences attributed to seasonal variation in diet, climate or animal movement. Because several months are required to obtain mature enamel in large mammals, modifications in the isotopic composition of environmental parameters are not instantaneously recorded, and stable isotope analysis of tooth enamel returns a time-averaged signal attenuated in its amplitude relative to the input signal. For convenience, stable isotope profiles are usually determined on the side of the tooth where enamel is thickest. Here we investigate the possibility of improving the time resolution by targeting the side of the tooth where enamel is thinnest. Observation of developing third molars (M3) in sheep shows that the tooth growth rate is not constant but decreases exponentially, while the angle between the first layer of enamel deposited and the enamel-dentine junction increases as a tooth approaches its maximal length. We also noted differences in thickness and geometry of enamel growth between the mesial side (i.e., the side facing the M2) and the buccal side (i.e., the side facing the cheek) of the M3. Carbon and oxygen isotope variations were measured along the M3 teeth from eight sheep raised under controlled conditions. Intra-tooth variability was systematically larger along the mesial side and the difference in amplitude between the two sides was proportional to the time of exposure to the input signal. Although attenuated, the mesial side records variations in the environmental signal more faithfully than the buccal side. This approach can be adapted to other mammals whose teeth show lateral variation in enamel thickness and could potentially be used as an internal check for diagenesis. © 2012 Elsevier Ltd.

Food products, such as meat, from grassland production systems have ‘added value’ for both food producers and consumers because of the perceived nutritional value of such products and the environmental acceptability of the production system itself. To differentiate these products from competing products produced without, or with minimal, grass inputs, robust authentication methods are required. This review reports on the application of stable isotope, α-tocopherol stereoisomer and metabolite analyses to authenticate grass-fed beef. The potential for metabolically inert animal tissues to provide an archival record of changes to diet and of urine to yield information, non-invasively, about grass-fed beef production systems is discussed.

To examine the effect of a modification of a typically Irish dairy calf-to-beef production system, Charolais × Friesian steers were offered a finishing ration of grass silage ad libitum and 5.6 kg concentrates daily for 174 days prior to slaughter at 25 months of age or grass silage ad libitum for 174 days, followed by pasture for 167 days and slaughter at 30 months of age. Finishing at pasture increased carcass weight (376 vs. 342 kg) but did not affect intra-muscular lipid concentration (28 vs. 24 g/kg). Finishing at pasture decreased Longissimus thoracis et lumborum lightness (35.6 vs. 36.9) and increased shear force of muscle at 2 (8.54 vs 4.32) and 7 days (5.21 vs 3.64 kg) post-mortem but not at 14 days post-mortem (4.45 vs. 3.42 kg). Finishing at pasture did not affect the sensory characteristics of tenderness, juiciness, firmness or chewiness and tended (P

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.

The chemical composition, fatty acid (FA) profile and antioxidant potential of beef from steers fed corn (CDG) or wheat (WDG) dried distillers’ grains were determined. Thirty-six Charolais and Limousin-sired steers (421.9 ± 38.9 kg) were blocked by breed and body weight and randomly assigned to one of three dietary treatments (n = 12 steers/treatment). Treatments consisted of ad libitum grass silage supplemented with concentrate ration (4.0 kg dry matter basis daily) containing either barley/soybean meal (control), 80% CDG or 80% WDG (as-fed basis) fed for 124 days pre-slaughter. Following slaughter, the longissimus thoracis muscle (LT) was excised at 48 h post-mortem, vacuum packaged and aged for 14 days prior to subsequent analysis. Feeding CDG increased (P < 0.05) the pH and decreased the ash content of LT relative to the control. Dietary CDG (P < 0.05) increased the protein content of LT compared to WDG. The proportion of C14:0 (P < 0.05) was lower in LT from steers fed WDG relative to the control whereas the percentage of C15:0 and C20:0 (P < 0.01) were greater in LT from WDG compared to the control. Both CDG and WDG increased (P < 0.05) the percentage of conjugated linoleic acids (c-9 t-11+t-9 c-11 18:2) and tended to increase the percentage of α-linolenic acid (P= 0.08), C22:2 n-6 (P = 0.05) and polyunsaturated FA (PUFA, P = 0.06) compared to the control. There was no treatment effect (P > 0.05) on antioxidant status (total phenol and α-tocopherol contents) or activity (radical scavenging and iron-chelating activities, and iron-reducing antioxidant power) of LT. In addition, dietary CDG or WDG did not influence lipid or oxymyoglobin oxidation in muscle homogenates incubated with iron/ascorbate pro-oxidants. Overall, the inclusion of distillers’ grains in supplementary concentrates may improve the FA composition of beef irrespective of distillers’ grains type.

Nitrogen (N) excretion from cattle contributes to water and air pollution. The objective was to determine the effects of inorganic fertiliser N application rate to mid-season grass (July-August) on herbage chemical composition, and intake, digestion and N-balance in beef cattle. Sixteen Charolais steers (live weight 568 kg, S.D. 22.1) were used in a randomised block design experiment. Treatments were zero-grazed grass herbage (predominantly Lolium perenne) harvested 21 d after receiving either 15 (LN) or 80 (HN) kg N/ha. Herbage was offered ad-libitum daily and dry matter (DM) intake measured during a 12-d diet adaptation phase and at 0.9 of this DM intake during the subsequent 10-d period in metabolism stalls. Total faeces and urine were collected on a 48-h and 24-h basis, respectively, for 8 d. Blood samples were obtained by jugular venepuncture immediately before, and 3 and 6 h post-feeding on d 12 and 22; plasma urea concentrations for the six sampling times were averaged giving one value per treatment. Data were analysed using AVOVA with terms for treatment and block in the model. Herbage DM concentration was 138 vs. 149 g/kg, and crude protein concentration was 206 vs. 156 g/kg DM, respectively, for HN and LN. Herbage DM intake (7.8 kg/d) and in vivo DM digestibility (816 g/kg) did not differ (P>0.05) between treatments. Compared to LN, N intake, N digestibility and faecal N loss was 75 g/d, 34 g/kg and 5 g/d greater, respectively, for HN (P

This study aimed to quantify the methane emissions and feed intake, performance, car- cass traits, digestibility, and rumen fermentation char- acteristics of finishing beef cattle offered diets based on whole-crop wheat (WCW) silages differing in grain content and to rank these relative to diets based on grass silage (GS) and ad libitum concentrates (ALC). In Exp. 1, a total of 90 continental crossbred steers (538 ± 27.6 kg of BW (mean ± SD)) were blocked by BW and assigned in a randomized complete block design to 1 of 6 treatments based on 4 WCW silages (grain-to- straw plus chaff ratios of 11:89 (WCW I), 21:79 (WCW II), 31:69 (WCW III), and 47:53 (WCW IV)), GS, and ALC. Increasing grain content in WCW silage resulted in a quadratic (P = 0.01) response in DMI, with a linear (P < 0.001) increase in carcass gain (CG; 577 (WCW I), 650 (WCW II), 765 (WCW III), and 757 g/d (WCW IV)). The G:F also increased linearly (P < 0.001) in response to increasing the grain content of WCW si- lage. A quadratic (P < 0.01) response in daily methane output (295 (WCW I), 315 (WCW II), 322 (WCW III), and 273 g/d (WCW IV)), measured using the sulfur hexafluoride tracer technique, was observed in response to increasing the grain content of WCW; however, lin- ear decreases were observed when expressed relative to DMI (P = 0.01) and CG (P < 0.001). Cattle offered GS exhibited carcass gains similar to those offered WCW silage diets and had greater methane emissions than cattle in any other treatment when expressed relative to DMI. Cattle offered ALC exhibited greater (P < 0.01) carcass gains and decreased (P < 0.001) methane emissions, irrespective of the unit of expression, com- pared with cattle in any of the silage-based treatments. In Exp. 2, rumen fermentation parameters were deter- mined using 4 ruminally cannulated Rotbunde-Holstein steers (413 ± 30.1 kg of BW) randomly allocated among WCW I, the average of WCW II and III (WCW II/III), WCW IV, and GS in a 4 × 4 Latin square design. Ru- minal pH and total VFA concentration did not differ across dietary treatments. Molar proportion of acetic acid decreased (P = 0.01), with propionic acid tend- ing to increase (P = 0.06) with increasing grain con- tent. It was concluded that increasing the grain content of WCW silage reduced methane emissions relative to DMI and CG and improved animal performance. How- ever, the relativity of GS to WCW in terms of meth- ane emissions was dependent on the unit of expression used. Cattle offered ALC exhibited decreased methane emissions and greater performance than those offered any of the silage-based treatments.

Quantitative reconstruction of paleodiet by means of sequential sampling and carbon isotope analysis in hypsodont tooth enamel requires a precise knowledge of the isotopic enrichment between dietary carbon and carbon from enamel apatite ( e D–E ), as well as of the timing and duration of the enamel mineralization process (amelogenesis). To better constrain these parameters, we performed a series of controlled feeding experiments on sheep ranging in age from 6 to 24 months-old. Twenty-eight lambs and 14 ewes were fed isotopically distinct diets for different periods of time, and then slaughtered, allowing the timing and rate of molar growth to be determined. High resolution sampling and stable carbon isotope analysis of breath CO 2 performed on six individuals following a diet-switch showed that 70–90% of dietary carbon had turned over in less than 24 h. Sequential sampling and carbon isotopic analysis was performed on the first (M 1 ) and second (M 2 ) lower molars of four lambs as well as on the third lower molar (M 3 ) of 11 ewes. The changes in diet were recorded in all molars. We found that the length of enamel matrix apposition is approximately one-quarter of the final tooth length during crown extension, and that enamel maturation spans slightly less than 3 months in M 1 , and 4 months in M 2 and M 3 . Portions of enamel in equilibrium with dietary carbon were used to calculate e D–E values. Animals on grass silage diets had values similar to previous observations, whereas animal switched to pelleted corn diets had values ca. 4‰ lower, a pattern consistent with lower methane production observed for animals fed concentrate diets. The tooth enamel forward model of Passey and Cerling (2002) closely predicted the amplitude of isotope changes recorded in tooth enamel, but slightly underestimated the rate of isotope change, suggesting that the rate of accumulation of carbonate during maturation may not be constant over time. Although stable isotope profiles in tooth enamel represent underdetermined systems, our results demonstrate that they can provide useful information about dietary variability if the mineralization process is taken into account.

Longissimus dorsi (LD) muscle from 60 Charolais crossbred heifers, aged for 14 days was used to investigate the effect of cooking on the content of PUFA and CLA fatty acids. Animals were offered a control diet of grass silage and concentrates (CO) or rations designed to enhance the concentration of CLA in tissue, i.e. unsupplemented grazed pasture (G), sunflower-oil supplemented grazing (SFG) or linseed-oil oil supplemented grazing (LSG). The SFG diet was the most effective for increasing the concentration of CLA but also caused the highest n −6/ n −3 fatty acid ratio. There were no changes in the relative distribution of fatty acids upon cooking (140 °C for 30 min) and this procedure can be recommended because it preserves the nutritional value of the meat. It is concluded that irrespective of the change in the fatty acid composition of LD due to alteration in the diet of the cattle, cooking did not cause thermal degradation of PUFA, or thermal degradation or oxidative synthesis of CLA.

The objective of this study was to examine the effect of level and duration of feeding of an n-3 PUFA-enriched fish oil (FO) supplement in combination with soybean oil (SO) on the transcriptional regulation of Delta(9)-desaturase gene expression in bovine muscle. Beef bulls (n = 40) were assigned to 1 of 4 iso-lipid and isonitrogenous concentrate diets fed for ad libitum intake for a 100-d finishing period. Concentrates were supplemented with one of the following: 1) 6% SO (CON); 2) 6% SO + 1% FO (FO1); 3) 6% SO + 2% FO (FO2); or 4) 8% palmitic acid for the first 50 d and 6% SO + 2% FO for the second 50 d [FO2(50)]. Samples of LM were harvested and concentrations of fatty acids were measured. Total RNA was isolated and the gene expression of Delta(9)-desaturase was determined. The mRNA expression of putative regulators of Delta(9)-desaturase gene expression, sterol regulatory element binding protein-1c (SREBP-1c) and peroxisome proliferator activated receptor-alpha (PPAR-alpha), were also measured in the CON and FO2 groups. Expression of mRNA for Delta(9)-desaturase was decreased (P 0.24). Expression of mRNA for SREBP-1c was decreased 2-fold in FO2 compared with CON (P 0.30). There was a positive relationship between Delta(9)-desaturase and SREBP-1c gene expression (P < 0.01), but the expression of both genes was negatively related to tissue concentrations of n-3 PUFA (P < 0.05) and positively related to concentration of n-6 PUFA (P < 0.01). Simultaneous enhancement of tissue concentrations of CLA and n-3 PUFA concentrations in bovine muscle may be hindered by negative interactions between n-3 PUFA and Delta(9)-desaturase gene expression, possibly mediated through reduced expression of SREBP-1c.