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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.

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.

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

In grass-based beef production systems (PS), early maturing (EM) breed types may be preferable to late maturing (LM) breed types in achieving adequate fat cover. Biochemical and organoleptic characteristics of muscle from suckler bulls were investigated in EM and LM (n = 28/breed) assigned to one of two PS (ad libitum concentrates and grass silage to slaughter (C) or ad libitum silage plus 2 kg concentrate daily during winter followed by 99 days at pasture and then an indoor finishing period on C (GSPC)) in a breed type × 2 PS factorial arrangement of treatments. Bulls were managed to have a common target carcass weight of 380 kg. Intramuscular fat (IMF) content was higher ( 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.

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.

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

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.

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.

The effects of varying the grain (G) to straw (S) ratio (G:S) of whole-crop wheat and barley silages on intake and digestibility and whole-crop barley silage on rumen fermentation characteristics were examined in two parallel studies. For the intake and digestibility study, eight Aberdeen Angus cross-bred steers (mean bodyweight 407 kg (S.D. 24.2)) were used in two (barley and wheat) 4 × 4 Latin Square designed experiments. The dietary treatments were four G:S ratios: 0:100, 30:70, 60:40 and 90:10. Intake of grain linearly increased ( P P P >0.05) was observed in total dry matter (DM) intake (DMI) or in DMI per kg liveweight. There was a positive linear ( P P P P P P P P P P P iso - and n -butyric acid, iso - ( P n - ( P P P P P >0.05) was found on the fractional clearance rates of DM, OM, aNDFom or starch or on liquid passage rate. It is concluded that increasing the G:S ratio in whole-crop wheat or barley silage linearly increased the intake of digestible nutrients for both wheat and barley and increasing the G:S ratio for whole-crop barley increased the concentration of fermentation products (total VFA, ammonia and the molar proportions of the VFAs, except acetic acid) in the rumen.

Seventy beef steers, mean initial live-weight 424 (S.D. 33.0) kg, were blocked by live-weight and breed and allocated to one of 5 dietary treatments in a randomised complete block design. Treatments, including supplementation with 3 kg concentrates/head/day, were grass silage (GS), maize silage (MS), fermented whole-crop wheat (FWCW), urea-treated, processed whole-crop wheat (UPWCW), and ad libitum concentrates supplemented with 5 kg grass silage/head/day (ALC). The grain in urea-treated, processed whole-crop wheat (WCW) was cracked and the crop ensiled with a urea plus urease-based additive. The mean dry matter (DM) of the grass silage, maize silage, fermented WCW and urea-treated, processed WCW was 174, 315, 404 and 716 g/kg, respectively. Total DM intake and carcass growth were lowest for GS (P

Our objective was to determine the effect of breed (B) and slaughter age/weight on the fatty acid composition, particularly the conjugated linoleic acid (CLA) concentration of beef. Two strains of a dairy breed [Holstein–Friesian (HF) (n = 16 steers/strain)] and a late-maturing breed [Belgian Blue × Holstein–Friesian (BB) (n = 16 steers)] were used. The HF strains were either of New Zealand (NZ) or European–American (EU) descent (selected in a grazed grass or a high concentrate nutritional environment, respectively). Animals were grown from calves to either a light (L; 560 kg) or heavy (H; 630 kg) target slaughter weight. Samples of M. longissimus dorsi were collected post-slaughter, lipids were separated into neutral (NL) and polar (PL) fractions, and fatty acid composition determined by gas-chromatography. The total fatty acid concentration and the concentrations of cis9, trans11 CLA, total CLA, MUFA and SFA in total intramuscular lipids were lower and the P:S ratio higher for BB than NZ or EU which did not differ. These differences largely reflected the changes in NL. The C18 desaturase index was higher for NZ than EU but EU did not differ from BB. Increasing slaughter weight/age increased the total fatty acid concentration and the concentrations cis9, trans11 CLA (P = 0.06), total CLA (P = 0.06), trans11 C18:1, MUFA and SFA and the C18 desaturase index and decreased the P:S ratio. The n-6:n-3 PUFA ratio was similar at the lighter slaughter weight/age for the three breeds/strains but increased for NZ and EU with increasing slaughter weight/age but was not affected in BB. It is concluded that the CLA concentration largely reflected muscle fatness but that increasing slaughter weight/age differentially affected the n-6:n-3 PUFA ratio of beef from early and late-maturing cattle.

International audience; The present study compared eight breeds of cattle differing in gender (heifers, bulls and steers) to determine associations between muscle characteristics and meat sensory qualities of the Longissimus thoracis muscle. Animal types differed in all the muscle characteristics and sensory qualities. Many correlations among muscle characteristics and among sensory qualities were consistent for most animal types. Isocitrate dehydrogenase (ICDH) activities allowed discrimination of muscles with respect to myosin heavy chain (MyHC)-I proportions for all animal types. Lactate dehydrogenase (LDH) and phos- phofructokinase (PFK) activities were positively correlated for most animal types. Overall liking was correlated with beef flavour and abnormal flavour in all animal types and with global tenderness for all animal types except for Charolais cross breed steers. For all animal types except for Angus×Friesian heifers, beef flavour and abnormal flavour were negatively correlated. Overall liking was not correlated with juiciness. PFK, ICDH and citrate synthase (CS) activities were strongly associated with tenderness, beef flavour and overall liking when average values for all animal types were used. However, associations between muscle characteristics and sensory qualities within animal types were weak and inconsistent.

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 effects of the type of grass silage and dietary inclusion of fish oil (FO) on the fatty acid profile of bovine intramuscular and subcutaneous adipose tissue were investigated. Eighty Friesian steers were assigned (n10) to unwilted or wilted silage, and to one of four rations which contained, per kg, 80 g of sunflower oil and either 0, 10, 20 or 40 g of FO replacing lard. Animals were slaughtered after 108 d and the fatty acid profile of the neutral, polar and total lipid fractions of theM. longissimus dorsi, and the total lipid fraction of the subcutaneous adipose tissue were determined. Wilting of grass prior to ensiling increased the concentration of conjugated linoleic acid (CLA) in intramuscular total lipid (P n-6:n-3 PUFA ratio. Increasing FO supply linearly increased (P cis-9,trans-11 andtrans-10,cis-12 isomers of CLA andtrans-11 18 : 1 predominantly in the neutral lipid fraction of intramuscular total lipid, and linearly decreased then-6:n-3 PUFA ratio. Wilting of grass prior to ensiling increased the concentration of CLA in subcutaneous adipose tissue (P cis-9,trans-11 CLA. From a human nutrition perspective, increasing the level of FO in the ration or wilting of grass prior to ensiling appear to modify the fatty acid composition of beef muscle favourably. However, the health implications of associated increases intransfatty acids remain to be elucidated.

The objective was to determine the feeding value of high moisture grain as an alternative to dry grain for finishing beef cattle. Winter wheat grain was harvested sequentially for rolling, acid treatment and ensilage (ER; 705 g dry matter (DM)/kg), urea whole grain treatment and anaerobic storage (UN; 746 g DM/kg) and whole grain propionic acid treatment and aerobic storage (rolled before feeding; PR; 849 g DM/kg). Friesian steers ( n = 120; mean starting live-weight 518 kg) were allocated on a live-weight basis to 12 replicate blocks and then randomly assigned from within blocks to ten treatments. Treatments were grass silage offered ad libitum together with (i) no wheat, (ii–iv) PR at 3 or 6 kg/head daily, or ad libitum , (v–vii) UN at equivalent DM allowances to (ii) and (iii) above, or ad libitum , (viii–x) ER at equivalent DM allowances to (ii) and (iii) above, or ad libitum . Mean daily live-weight gains were 852 (ER), 726 (UN) and 855 g (PR) (s.e. = 65.5; P P P ad libitum was 7.8, 8.3 and 8.2 kg (s.e. = 0.10; P P

The effect of supplementation of beef cattle diets with tea catechins (TC) (1000mg/animal/day) and rosemary extract (RE) (1000mg/animal/day), for 103 days preceding slaughter, on the oxidative stability of M. longissimus dorsi (LD) steaks was evaluated. Dietary supplementation with TC and RE did not increase plasma total antioxidant status (TAS), LD α-tocopherol concentrations or pH. In LD steaks stored aerobically or in modified atmosphere packs (80% O(2):20% CO(2)) (MAP) for up to 8 days at 4°C, surface redness (CIE 'a' redness value) and lipid stability (TBARS, mg MDA (malondialdehyde)/kg muscle) were not significantly improved as a result of supplementation with TC and RE. Similarly no improvement in the sensory properties and lipid stability of cooked LD slices, stored aerobically or in 30% CO(2):70% N(2) for up to 11 days at 4°C, was observed. An in vitro fermentation study demonstrated that TC and RE were not fermented to any great extent under simulated rumen conditions. Direct addition of TC (1000ppm) and RE (1000ppm) significantly (P

Duodenally and ruminally fistulated steers were offered grass silage and one of three concentrates at a ratio of 60: 40 (forage: concentrate on a dry-matter basis) : F0, F1 or F4 at 14 g/kg live weight. The concentrates were designed to be iso-lipid and to provide the same amount of sunflower oil but increasing amounts of fish oil : 0, 1 and 4 g per 100 g, respectively. Ruminal characteristics were measured along with fatty acid intakes and duodenal flows to determine the effect of fish oil on : ruminal pH, ammonia-N concentration, volatile fatty acid (VFA) concentration and polyunsaturated fatty acid (PUFA) metabolism. Fish oil had no significant effect on ruminal pH, ammonia-N concentration or the molar proportions of the major VFA, although total VFA concentration was significantly reduced at the highest level of fish oil inclusion. Fish oil significantly increased the flow of long chain PUFA, total conjugated linoleic acid and vaccenic acid to the duodenum and decreased the flow of stearic acid. Biohydrogenation, as determined by the net loss of fatty acid between the mouth and duodenum, of oleic and linolenic acid was not affected by fish oil inclusion and averaged 0·64 and 0·92, respectively. There was a small increase in the biohydrogenation of linoleic acid with increasing fish oil from 0·89 to 0·92 (P< 0·01) on F0 and F4, respectively. Biohydrogenation of the long chain PUFA C20 : 5(n-3) and C22 : 6(n-3) increased from 0·49 and 0·74 to 0·79 and 0·86 (P< 0·01), respectively when fish oil in the concentrate increased from 1 to 4 g per 100 g. The net effect of fish oil on lipid metabolism appears to inhibit the transition of vaccenic acid to stearic acid in the rumen resulting in a build up of this intermediate in the biohydrogenation pathway of C18 PUFA.

Duodenal fistulated steers were offered grass silage at 14 g/kg liveweight and one of three concentrates at a ratio of 60:40 (forage:concentrate on a dry matter basis): FISH0, FISH1 or FISH2 designed to be iso-lipid and to provide the same amount of sunflower oil but increasing amounts of fish oil: 0, 1 and 4%, respectively. Fatty acid intakes and duodenal flows were examined to determine the effects of fish oil on polyunsaturated fatty acid (PUFA) metabolism. Fish oil significantly increased the flow of long chain PUFA, conjugated linoleic acid and trans vaccenic acid to the duodenum and decreased the flow of stearic acid. Biohydrogenation of linoleic and linolenic acids was not affected by fish oil inclusion.

The aim of the study was to generate a database of ruminal degradability of dry matter (DM), and organic matter (OM) of different sources of concentrate ingredients (classified as protein, energy or protein+energy feeds) commonly offered to ruminants in European countries. The ruminal disappearance of DM and OM was measured using the in situ nylon bag technique, where the test feedstuffs were subject to ruminal incubation in four Friesian steers offered grass silage and concentrate. Disappearance of DM and OM from the test feeds from the rumen was measured at 0, 2, 4, 8, 14, 24 and 48 h. The exponential model of Orskov and McDonald (1979) was used to calculate degradation kinetics. Test protein feeds were sunflower meal (SUN), rapeseed meal (RAP), soyabean meal (SBM) and cottonseed meal (CSM). Test energy feeds were palm kernel meal (PK), pollard (PO), barley (BA) and beet pulp (BP). Test protein+energy feeds were maize distillers grains (MDG), maize gluten feed (MGF), copra meal (CO) and malt combings (MC). The effective degradability (degradability of feed, whilst considering rate of flow of feed from rumen to small intestine) of DM (EDDM) and OM (EDOM) in the protein feed SBM, where outflow rate k=0.02, was not influenced (P>0.05) by the sample of feed used. For the feeds classified as protein+energy feeds, the EDDM in MGF and MC were not affected (P>0.05) by the sample of feed for k=0.02. For the remainder of the concentrate feedstuffs used in this study, the sample of feed used had a pronounced effect on in situ degradability values. These data have shown that for the majority of feeds examined in this study, the different sources of any one feed are not equal in nutritive value and it is necessary to screen feeds for nutritive value before using them in ration formulation systems.

The aim of the study was to generate a database of small intestinal digestibility (SID) of different sources of concentrate ingredients commonly offered to ruminants in European countries. Test protein feeds were sunflower meal (SUN), rapeseed meal (RAP), soyabean meal (SBM) and cottonseed meal (CSM). Test energy feeds were palm kernel meal (PK), pollard (PO), barley (BA) and beet pulp (BP). Test protein+energy feeds were maize distillers grains (MDG), maize gluten feed (MGF), copra meal (CO) and malt combings (MC). The ruminal undegradable protein (RUP) portion of the test feedstuffs was obtained by ruminal incubation in four Friesian steers offered grass silage and concentrate. The RUP fraction was digested with pepsin and pancreatin enzymes (PPD) or placed into the duodenal cannula of two Friesian cows using the mobile bag technique, which were recovered in the faeces. The average in situ SID (g/kg) of CSM, RSM, SBM, SUN, BA, BP, PK, CO, MDG, MGF and MC was 834 (S.D. 61), 711 (S.D. 47), 978 (S.D. 9), 586 (S.D. 170), 427 (S.D. 80), 712 (S.D. 24), 767 (S.D. 53), 816 (S.D. 38), 860 (S.D. 73), 656 (S.D. 65) and 510 (S.D. 41), respectively. Corresponding in vitro SID values (g/kg) were 641 (S.D. 65), 620 (S.D. 45), 840 (S.D. 27), 606 (S.D. 155), 445 (S.D. 36), 601 (S.D. 17), 640 (S.D. 63), 686 (S.D. 69), 756 (S.D. 63), 634 (S.D. 84) and 504 (S.D. 16), respectively. These results show that the SID of feeds can vary substantially between different sources and indicates that different feeds should be screened for their nutritive value as a result. As the relationship between in situ ( Y ) and in vitro ( X ) SID is best described by the linear regression equation Y =−91.9+12.7 X ( r =0.91), indicating a close relationship between results obtained using both techniques, the in vitro PPD technique offers a quick and reliable method for SID of feeds to be screened on a regular basis.

The objective of this study was to determine the impact of increasing the rate of carcass growth of steers grazing autumn grass by either supplementing with concentrates or by increasing grass supply on fatty acid composition of triacylglycerols within the M. longissmus thoracis . One hundred and ten steers (567 kg) were assigned to ten dietary treatments in a 3 (daily grass allowances: 6, 12 and 18 kg dry matter (DM)/animal) by 3 (daily concentrate allowances: 0, 2.5 and 5 kg/animal) factorial experiment with a control group offered concentrates ad libitum. Animals were slaughtered after 100 days and lipid extracted from samples of the M. longissmus thoracis for fatty acid analysis. There was an interaction ( P P P P P P P

The effect of feeding level (11 and 17 g dry matter (DM)/kg body weight (BW) per day) and ratio of grass silage to concentrate (250:750, 500:500 and 750:250 g/kg DM) on the in situ ruminal degradability of concentrate ingredients was examined. Six ruminally fistulated Friesian steers were used in a six (treatments) by six (21 days period) Latin square experiment. Ruminal disappearance of DM, nitrogen (N) and organic matter (OM) from the test feeds was measured at 0, 2, 4, 8, 14, 24 and 48 h. The exponential model of Orskov and McDonald was used to estimate degradation kinetics. Neither level of feeding nor forage to concentrate ratio had a significant effect on the ‘a’, ‘b’, ‘c’ values or effective degradability (ED) of DM, N and OM, except for an effect of diet on the ED of OM (P

Thirty-eight cross-bred wether lambs, initial liveweight 35.21±0.75 kg were used to evaluate the effects on growth and carcass composition of passive immunisation with anti-ovine adipose plasma membrane immunoglobulin G (IgG). Antibodies were raised in donkeys by active immunisation with sheep adipocyte membrane protein in Freund's complete adjuvant followed by boosting at 3, 5 and 15 weeks and subsequently at 4-month intervals with membrane protein in Freund's incomplete adjuvant. An IgG fraction was prepared from pooled serum by ammonium sulphate precipitation and dialysis. Ten lambs were slaughtered and the remaining lambs ( n =14/group) were injected subcutaneously with 80 ml of IgG from immunised (treated) or non-immunised donkeys (control) on 4 consecutive days at the beginning of the study. Following a 91-day test period the animals were slaughtered, the weights of internal organs and fat depots recorded and carcass composition determined by dissection. Treatment did not affect preslaughter liveweight (Control=47.8 kg, Treated=47.4 kg) or carcass weight (Control=25.9 kg, Treated=24.7 kg). Liver weight tended to be increased ( P =0.07) by treatment (from 751 to 905 g), while the weights of other organs were not affected. The weights of the omentum and kidney/channel fat depots were reduced ( P P P P

The objective of this study was to determine the effects on animal performance and rumen digestion characteristics of supplementing cattle grazing autumn grass offered at two levels of allowance, with concentrates formulated from different carbohydrate sources. Seventy-two steers (494 (s.e. 38·4) kg) were assigned to one of six treatments which were arranged in a two grass allowances (5·5 or 11 kg grass dry matter (DM) per head per day) by three concentrate types (starch, starch + fibre or fibre-based diets) factorial design. The experiment commenced on 22 August and had a mean duration of 84 days. Concentrates were formulated to have similar metabolizable energy and crude protein and animals were offered 5 kg per head daily. Grass allowances were offered daily and concentrates were offered individually. Six rumen fistulated steers were used concurrently in a Latin square design to determine the effect of the diets on rumen digestion characteristics. Grass and concentrates degradabilities were measured using the nylon bag technique. The concentrate DM was degraded at 0·189, 0·102 and 0·094 per h for the starch, starch + fibre and fibre-based diets, respectively. Concentrate carbohydrate source and grass allowance did not affect (P> 0·05) degradation rate of grass DM or nitrogen in the rumen, rumen fluid pH, rumen fluid concentration of volatile fatty acids, total lactic acid or ammonia concentration or plasma concentration of glucose, urea or beta-hydroxybutyrate. Animals offered the low grass allowance had larger (P< 0·05) diurnal variation in the rumen fluid acetate: propionate ratio than those offered the high grass allowance. Increasing grass allowance increased (P< 0·01) carcass gain whereas concentrate type had no effect. There was no interaction between concentrate carbohydrate source and grass allowance on any of the production variables measured. It is concluded that the rumen environment in cattle grazing autumn grass buffered the effects of concentrate carbohydrate degradability such that similar productivity was achieved with each concentrate.

The objectives of this study were (i) to examine the effects on rumen and blood variables when grass silage (GS) was replaced with whole crop fodder beet silage (FBS) in the diet of beef cattle, and (ii) an abrupt change from GS to FBS. Six rumen-fistulated Friesian steers (initial bodyweight (BW) 416 kg, SD 43) were offered GS ad libitum for four weeks. The dry matter (DM) consumed daily by each animal in that period (14.3 g/kg BW) was used as the daily allowance for that animal for three consecutive two-week periods, during which the animals were offered diets consisting of increasing proportions (420, 880 and 1000 g/kg) of FBS DM in the total DM. FBS was then offered ad libitum for 14 days. Cattle were then offered GS ad libitum for 14 days, after which GS was substituted with FBS for 14 days. The DM content (g/kg) and contents (g/kg DM) of organic matter, crude protein and total volatile fatty acids (VFA) were 220 and 174, 905 and 749, 153 and 115, and 26 and 75 for GS and FBS, respectively. Animals fed the diets of 0, 420, 880 and 1000 g FBS DM/kg DM had rumen pH, concentrations of ammonia (mg/l), l-lactic acid (mmol/l), d-lactic acid (mmol/l) and VFA (mmol/l) of 6.44, 6.18, 6.61 and 6.75 (linear p

Passive immunisation of sheep with anti-ovine adipocyte membrane serum was examined. Antibodies were raised in donkeys by primary immunisation with sheep adipocyte plasma membrane protein in Freund's complete adjuvant followed by booster injections at 3, 5 and 15 weeks and subsequently at 4-month intervals with Freund's incomplete adjuvant. Finnish Landrace crossbred sheep were injected with 50 ml of donkey serum on three consecutive days. A control group (n=16) received serum intravenously from a donkey which had not been immunised, while the other sheep were treated subcutaneously (SC, n=16) or intravenously (IV, n=10) with anti-ovine adipocyte membrane serum. Eight SC and eight control sheep were slaughtered after 5 weeks and the remainder after 12 weeks. Immunisation against adipocyte plasma membranes decreased (P

The objective of this study was to determine if isoenergetic rations, designed to result in different ruminal fermentation patterns, altered growth and carcass composition in wethers. Two basal rations, based either on starch (S) or a digestible fibre/sugar mixture (F) were formulated. Sodium propionate was included at 0 (C) or 40 g/kg (P) to give four isoenergetic (12 MJ metabolisable energy/kg dry matter) and isonitrogenous (165 g crude protein/kg dry matter) rations. When fed at 22 g/kg bodyweight (BW)+75 g hay daily to four ruminally fistulated sheep in a 4 (ration) by 4 (period) Latin square experiment, there was no difference between diets in mean volatile fatty acid concentrations in ruminal fluid (92, 90, 86 and 105 (S.E. 7.5) mmol/l for SC, SP, FC and FP, respectively). The acetate to propionate ratio was lower (P

Ardacin is an antibacterial glycopeptide with ruminal activity. The objective of this study was to determine its effects on rumen fermentation, soyabean meal degradability and concentrations of selected metabolites in plasma of steers. Six rumen fistulated steers (initial bodyweight 622, S.D. 99.8 kg) were used in a replicated 3 (0, 0.5 or 1.0 mg ardacin kg−1 bodyweight) by 3 (21 day periods) Latin square experiment and fed a diet of 450 g concentrate and 550 g grass silage kg−1 dry matter (DM) at a daily allowance of 13.5 g DM kg−1 bodyweight. Dietary inclusion of ardacin did not affect mean rumen fluid pH or concentrations of ammonia or total volatile fatty acids in rumen fluid. Dietary inclusion of ardacin increased (linear, P < 0.05) the molar proportion of propionate, decreased (linear P < 0.001) the molar proportion of acetate and decreased (linear, P < 0.01) the acetate: propionate ratio in rumen fluid. At 8 h after the first feed, the butyrate proportion was higher (P < 0.05) in animals fed 1.0 mg ardacin kg−1 bodyweight than in the other treatments. When compared to animals not offered ardacin, the molar proportion of valerate was lower (P < 0.05) in animals fed 0.5 mg kg−1 bodyweight and tended to be higher (P < 0.1) in those fed 1.0 mg kg−1 bodyweight. The rate of disappearance of soyabean meal from nylon bags incubated in the rumen was lower (linear, P < 0.05) in steers fed ardacin. Plasma concentrations of glucose, non-esterified fatty acids and 1-lactic acid were unaffected by inclusion of ardacin in the diet. Plasma urea concentration tended to be increased in the 8–12 h period after the first feed. It is concluded that ardacin altered rumen fermentation in a dose-dependent manner in a direction suggestive of improved growth and/or feed conversion efficiency and may increase the quantity of dietary protein supplied to the small intestine.

Plants are the primary source of omega-3 polyunsaturated fatty acids (PUFA) in the land and marine food chains and provide the basis to produce milk and meat with enhanced nutritional attributes. This chapter describes the range of omega-3 PUFA sources used in animal feeding – including forages, oilseeds and fish oils – and identifies the factors controlling the incorporation of omega-3 PUFA into milk and meat. There is a particular focus on the challenges of increasing omega-3 PUFA in ruminant products as a consequence of rumen biohydrogenation, as well as limitations on elongation/desaturation of omega-3 PUFA and on incorporation of the longer chain omega-3 PUFA into triacylglycerols. The chapter also considers the implications of seeking to modify omega-3 PUFA in products for livestock health and fertility, as well as for product quality attributes such as flavour and shelf-life.

The effects of cimaterol on the growth and nucleic acid concentrations in selected skeletal muscles in purebred Finnish-Landrace lambs were examined. Lambs (initial bodyweight (BW) = 26.3 kg; n = 12/treatment) were individually offered a pelleted concentrate diet ad libitum which contained either 0 or 10 ppm cimaterol. An additional group (n = 6) were slaughtered at the beginning of the study. Half of each treatment group was slaughtered after 36 days of treatment and the remainder after 64 days. Selected muscles were dissected from the right side of each carcass. Muscle type was a significant source of variation for muscle weight and nitrogen content. Cimaterol increased (P < 0.05) the weight of the pool of skeletal muscles examined after 36 and 64 days of treatment and the mean nitrogen content after 64 days of treatment. After 64 days, the weights of the semimembranosus, quadriceps femoris and longissimus thoracis et lumborum muscles were increased (P < 0.05) but the weight of the semitendinosus, adductor, psoas minor, psoas major, infraspinatus and supraspinatus muscles were not affected by cimaterol treatment. Within the pool of muscles examined, cimaterol did not affect muscle distribution at either slaughter day. The allometric coefficient for growth of the psoas major was increased (P < 0.1) and that of quadriceps femoris and supraspinatus decreased (P < 0.01) by cimaterol treatment. The allometric coefficient of nitrogen deposition in the quadriceps femoris muscle was increased (P < 0.1) by cimaterol treatment. After 64 days of treatment, cimaterol decreased (P < 0.05) the RNA concentration in the semimembranosus, psoas major, supraspinatus and longissimus thoracis et lumborum muscles and the DNA concentration in the semimembranosus and quadriceps femoris muscles. It is concluded that the effects of cimaterol on skeletal muscle growth were largely muscle independent but that the mechanism of growth differed among muscles.

The effects of cimaterol on feed conversion efficiency, body composition, nitrogen retention and plasma concentrations of selected plasma hormones and metabolites in pure-bred Finnish-Landrace castrated male lambs were examined. Lambs (initial bodyweight (BW) = 26.3 kg; n = 12/treatment) were individually offered a pelleted concentrate diet ad libitum which contained either 0 or 10 ppm cimaterol. An additional group (n = 6) was slaughtered at the beginning of the study. Half of each treatment group was slaughtered after 36 days of treatment and the remainder after 64 days. Full carcass dissection was carried out only on lambs slaughtered after 64 days of cimaterol treatment. Nitrogen retention and ration digestibility were measured between days 20 and 36, while blood samples were collected once/day periodically, and intensively on day 56. Dietary inclusion of cimaterol increased (P < 0.05) BW gain and feed conversion efficiency (whether measured for 36 or 64 days), decreased (P < 0.05) internal body fat and dissectible carcass fat deposition and increased (P < 0.05) carcass weight and lean meat deposition in the carcass. Both absolute nitrogen retention and nitrogen retention as a proportion of absorbed nitrogen were higher (P < 0.05) in lambs treated with cimaterol. Plasma concentrations of urea and insulin tended to be lower and creatinine and non-esterified fatty acids higher in samples collected on a periodic basis during the study, but there were day of experiment by cimaterol interactions for these variables. Mean growth hormone and insulin concentrations and the frequency of growth hormone pulses, measured on day 56 were lower in cimaterol-treated lambs. It is concluded that the measured repartitioning effects of cimaterol were within the range of effects observed for other breeds of sheep, but that its effects on growth and growth hormone parameters appear to be peculiar to this breed of sheep.

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.

The effects of altering the glucogenic potential of the diet of wether lambs (initial body weight 56·4 kg) offered an energy allowance of 0·25 that required for maintenance on body-weight loss, nitrogen retention and blood and rumen fluid parameters were examined. Whole barley was offered alone or substituted on an isoenergetic basis with 40 or 120 g of a blend of glucose precursors (polyhydric alcohols, propylene glycol, sodium propionate) absorbed on to palm kernel meal (acetona meal), to 36 lambs (no. = 12 per treatment) for 8 weeks. Substituting barley with 40 g acetona meal had a small but non-significant effect in decreasing body-weight loss and plasma aspartate amino transferase activity and in increasing plasma insulin concentration. Increasing the glucogenic potential of the diet by substituting barley with 120 g acetona meal decreased body-weight loss in the early phase of the study, decreased plasma concentrations of non-esterified fatty acids and increased the proportion of propionate in volatile fatty acids in rumen fluid, plasma aspartate amino transferase and gamma-glutamyl transferase activities and plasma insulin concentrations. Increasing the glucogenic potential of the diet did not affect nitrogen retention or plasma glucose concentration. It is concluded that increasing the glucogenic potential of the diet of lambs resulted in an increase in metabolic efficiency at the onset of negative energy balance which was mediated through a change in plasma insulin concentration. The absence of a significant difference in body-weight loss between the diets in the latter part of the study reflects the lack of sustained ketosis.

The effects on rumen fermentation and blood metabolites when barley or cane molasses were offered as isoenergetic and isonitrogenous supplements at 610 g kg−1 of total dietary dry matter (DM) intake were studied in steers fed grass silage. Six rumen fistulated steers were used in a 2 (supplements) × 2 (periods, 28 days duration) cross-over experiment. The animals were offered 35.2 g supplement DM and 22 g silage DM kg−1 bodyweight0.75 daily at 08:30 and 16:30. Rumen fluid samples were collected from all animals on Days 27 and 28 of each period before the morning feed and 1, 2, 3, 6, 8, 9, 10, 14 and 24 h thereafter. Blood samples were collected from each steer on Day 26, before the morning feed and 1 and 3 h thereafter. Mean rumen pH (6.9 vs. 6.9), concentration of total volatile fatty acids (71.2 vs. 71.7 mmol−1) and molar proportion of propionate (15.8 vs. 16.6) were similar for both supplements. The molasses-based supplement resulted in a lower (P < 0.01) rumen concentration (mg dl−1) of ammonia-N (5.6 vs. 9.3) and l-lactate (26.2 vs. 49.3), and as proportions of total volatile fatty acids, lower (P < 0.01) acetate (58.4 vs. 66.5) and higher (P < 0.01) butyrate (23.0 vs. 14.0) than the barley-based supplement. Type of supplement did not affect the concentration of haemoglobin in blood. Plasma glucose concentration was higher (P < 0.01) before the morning feed and mean plasma urea-N was lower (P < 0.06) in animals offered the molasses-based supplement. Sampling time significantly affected all blood metabolites and rumen fermentation variables measured. It is concluded that under the conditions of this study, plasma glucose and urea-N concentrations and the pattern of rumen fermentation differed between barley and molasses-based supplements to grass silage.

The effects of dietary inclusion of yeast culture (Yea-Sacc) on rumen fermentation and digestibility in vivo were examined. In a Latin square experiment with 30-day periods, four rumen fistulated steers were offered 0 or 10 g yeast culture per animal daily in a low quality (4 kg barley straw plus 2.5 kg barley/soyabean meal mixture per day) (L) or high quality (2 kg barley straw plus 8 kg barley/soyabean meal mixture per day) (H) diet. The diets were offered in two feeds at 08:00 h and 16:00 h with no refusals. Rumen samples were withdrawn on 2 days per period at 08:00 (before feeding), 12:00, 16:00, 20:00 and 24:00 h. Mean rumen pH, liquid outflow rate, molar acetate proportion and the acetate to propionate ratio were lower (P < 0.001) and the concentrations of total volatile fatty acids (VFA), ammonia and bacterial nitrogen and molar proportions of butyrate and isoacids were higher (P < 0.001) on Diet H. Rumen ammonia concentration was not affected when yeast was included in Diet L but was reduced (P < 0.05) when yeast was added to Diet H. Inclusion of yeast culture in Diet L decreased (P < 0.05) VFA 4 h after the second feed, but inclusion of yeast culture in Diet H increased (P < 0.1) VFA subsequent to the second feed. Degradability of cotton was lower on Diet H, but unaffected by yeast culture. In a replicated Latin square experiment with 34-day periods, 12 non-fistulated steers were offered the experimental diets. Digestibility of dry matter, organic matter and crude protein (CP) were higher (P < 0.001) and acid detergent fibre lower (P < 0.05) on Diet H. Digestibility of CP was decreased (P < 0.05) when yeast was included in Diet L, but not affected when yeast was added to Diet H. It is concluded that dietary inclusion of yeast culture had a small influence on rumen fermentation parameters and in vivo digestibility, but that its effect on nitrogen metabolism appeared to be dependent on the nitrogen content of the basal diet.