Search

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.

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).

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.

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.

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.

This experiment aimed to quantify the relative intake, digestibility, rumen fermentation, performance and carcass characteristics of beef cattle fed diets based on good quality whole-crop wheat and barley silages, each harvested at two cutting heights, and to rank these relative to good quality maize silage and an ad libitum concentrates-based diet. Ninety beef steers, initial live-weight 438 ± 31.0 kg, were allocated to one of the following dietary treatments in a randomised complete block design: maize silage (MS), whole-crop wheat harvested at a normal cutting height (WCW) (stubble height 0.12 m) or an elevated cutting height (HCW) (stubble height 0.29 m), whole-crop barley harvested at a normal cutting height (WCB) (stubble height 0.13 m) or an elevated cutting height (HCB) (stubble height 0.30 m), each being supplemented with 3 kg concentrates/head/day, and ad libitum concentrates (ALC) supplemented with 5 kg grass silage/head/day for the duration of the 160-day study. Mean dry matter (DM) of the maize silage, whole-crop wheat, head-cut wheat, whole-crop barley and head-cut barley was 301, 488, 520, 491 and 499 g/kg, respectively. There were no differences in total DM intake among treatments, or in rumen fermentation characteristics (except ammonia), or in DM digestibility among the forage-based treatments. Neutral detergent fibre digestibility was lower (P

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.

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.

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 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

The aim of this experiment was to quantify the relationship between autumn grass supply and concentrate supplementation level on grass intake and animal performance. One hundred and ten continental steers (567 kg) were assigned to 10 treatments. The experimental design was a three grass allowances (6, 12 and 18 kg dry matter (DM) per head daily) by three concentrate levels: (0, 2·5 and 5 kg per head daily) factorial with a positive control group offered concentrates ad libitum and no grass. Grass allowance was offered daily and concentrates were given individually. The experiment began on 22 August and all animals were slaughtered after a mean experimental period of 95 days. Grass intake was calculated using the n-alkane technique and diet digestibility using ytterbium acetate as an indigestible marker. There was an interaction (P < 0·05) between grass allowance and concentrate level for grass intake. At the low grass allowance there was no effect of offering animals supplementary concentrates on grass intake, at the medium and high grass allowances, supplementary concentrates reduced grass intake by 0·43 and 0·81 kg DM respectively per kg DM concentrate offered. Increasing grass allowance increased (P < 0·001) complete diet organic matter (OM) digestibility at all concentrate levels and supplementary concentrates increased (P < 0·001) complete diet OM digestibility only at the low grass allowance. Both offering animals supplementary concentrates (P < 0·001) and increasing daily grass allowance (P < 0·001) increased their carcass growth rate. Relative to the animals offered the low grass allowance and no concentrate, supplementing with concentrate increased carcass growth by 116 g/kg concentrate DM eaten whereas increasing the grass allowance, increased carcass growth by 38 g/kg DM grass eaten. As a strategy for increasing the performance of cattle grazing autumn grass, offering supplementary concentrates offers more scope than altering grass allowance.

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

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.

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.