Enteric methane from ruminants accounts for about 11-17% of methane generated globally, or 17-30% of methane from human activity. Methane arises from the activity of methanogens in the rumen that use hydrogen to reduce carbon dioxide, thereby preventing the accumulation of reducing equivalents, which would otherwise impede ruminal fermentation. Although this process is desirable from a fermentation perspective, it is energetically costly, as cattle emit 2-12% of their gross energy intake in this potent greenhouse gas (GHG). Many production practices aimed at increasing efficiency of production, such as including grain and ionophores in diets, also lower methane emissions. These practices were adopted long before issues arose over the role of methane from livestock in climate change. Dietary inclusion of free oils or oil-rich feeds (e.g. oilseeds, distillers' grains and micro-algae), biologically active plant compounds (e.g. condensed tannins, saponins and essential oils), rumen fermentation modifiers (e.g. yeast and bacterial direct-fed microbials), as well as improvements in forage quality may allow for further reductions in methane emissions from cattle. The optimum dietary strategy will depend on the particular farm, its geographic location, the feedstuffs available and the type of animals being fed. Reductions can occur as decreased methane output per animal per day or as decreased methane output per kg of meat or milk produced, but ultimately, it seems prudent that mitigation practices be assessed on the basis of the extent to which they reduce methane emissions per kg of meat or milk produced. Furthermore, potential mitigation practices need to be assessed from the perspective of the entire life cycle, as a reduction in GHG in one sector of the production cycle can often lead to changes in GHG emissions in another sector.

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Canadian beef consumption is approximately 31 kg per annum, or a third of all meats consumed. Beef is a nutrient-rich food, providing good quality protein, vitamins B-6 and B-12, niacin, iron, and zinc. However, animal fats have gained the reputation of being less healthy. The identification of the anticarcinogenic effects of beef extracts due to the presence of conjugated linoleic acid (CLA) has heightened interest in increasing the amount of CLA deposited in beef. Beef cattle produce CLA and deposit these compounds in the meat; thus, beef consumers can receive bioformed CLA. Beef contains both of the bioactive CLA isomers, namely, cis-9, trans-11 and trans-10, cis-12. The relative content of these CLA isomers in beef depends on the feeds consumed by the animals during production. Feeding cattle linoleic acid-rich oils for extended periods of time increases the CLA content of beef. Depending on the type and relative maturity of the pasture, beef from pasture-fed cattle may have a higher CLA content than beef from grain- or silage-fed cattle. In feedlot animals fed high-grain diets, inclusion of dietary oil along with hay during both the growth and finishing phases led to an increase in CLA content from 2.8 to 14 mg/g beef fat, which would provide 77 mg CLA in an 85-g serving of beef. The CLAs appear to be concentrated in intramuscular and subcutaneous fat of beef cattle, with the CLA trans-10, cis-12 isomer being greater in the subcutaneous fat.

This review considers sources of enzymes, measurement of enzyme activity, production responses to exogenous enzymes (beef cattle, dairy cattle, sheep, learning from animal experiments), modes of action (preconsumption effects, rumen effects), and steps towards improving exogenous enzymes for ruminants (matching the enzyme to the feed, lowering enzyme cost).

. 2006. In vitro ruminal digestion of anthocyanidin-containing alfalfa transformed with the maize Lc regulatory gene. Can. J. Plant Sci. 86: 1119-1130. In vitro ruminal digestion was conducted on novel "purple-green" alfalfa forage that accumulated anthocyanidin and proanthocyanidins through the expression of a maize bHLH anthocyanidin regulatory gene (Lc). The Lc-transgenic genotypes were compared with parental (non-transformed, NT) alfalfa in their in vitro ruminal fermentation, dry matter (DM) and N disappearances, and DM degradability. The transgenic genotypes expressed the Lc gene at different levels when grown under high light conditions, resulting in anthocyanidin contents as high as 136 µg g -1 DM. Lc genotypes had lower true DM disappearance than NT alfalfa at 0, 4 and 12 h of incubation, but not at 24 or 48 h. Compared with NT, Lc-transgenic genotypes had a lower content of rapidly soluble DM, but a similar content and rate of degradation of the slowly degradable DM fraction, and a similar lag time for digestion. True disappearance of N was lower for Lc-transgenic than NT alfalfa at the initiation of the incubation. The solubility of both DM and N were negatively correlated with the concentration of anthocyanidins measured in the forage. The results indicate that Lc-transformation reduced the initial rate, but not the extent of DM and N digestion of alfalfa in the rumen. These properties could improve the utilization of protein and possibly reduce the risk of bloat in ruminants consuming fresh alfalfa. However, further increasing the amount of anthocyanidins (or proanthocyanidins) produced in the forage may be required to make this a viable strategy for improved protein utilization and bloat prevention. Les auteurs ont examiné la digestion par le rumen in vitro du nouveau fourrage de luzerne « vert violacé » dans lequel l'anthocyanidine et les proanthocyanidines s'accumulent, consécutivement à l'expression du gène régulateur (Lc) de l'anthocyanidine bHLH du maïs. Ils ont comparé les génotypes transgéniques Lc aux lignées parentales (non modifiées, NM) de luzerne pour la fermentation dans le rumen in vitro, la disparition de la matière sèche (MS) et de l'azote (N) ainsi que la dégradation de la MS. Les géno-types transgéniques expriment le gène Lc à différents degrés quand on les cultive sous un vif éclairage, ce qui entraîne une accumulation d'anthocyanidine pouvant aller jusqu'à 136 µg par gramme de MS. Les génotypes Lc se caractérisent par une disparition véritable de la MS plus lente que la luzerne NM après 0, 4 et 12 h d'incubation, mais pas après 24 ou 48 h. Comparativement à la luzerne NM, les génotypes transgéniques Lc renferment moins de MS soluble rapidement, mais autant de MS dégradable lentement, le taux de dégradation de cette dernière étant analogue. Le décalage de la digestion est lui aussi similaire. L'azote disparaît plus lentement chez les lignées transgéniques Lc que chez la luzerne NM au début de l'incubation. La solubilité de la MS et du N présentent une corrélation négative avec la...

Water is an important nutrient for livestock production and is often provided on rangelands directly from ponds or dugouts. Cattle may defecate and urinate into the water thereby adding nutrients and reducing palatability. A study was conducted to examine the effects of water source on cattle production and behavior, to determine the relationship of selected chemical and biological constituents on the observed response and to test the effect of fecal contamination on water consumption. Four dugouts or ponds were selected at 4 sites: 2 in the Fescue Prairie near Stavely in southwestern Alberta, 1 in the Mixed Prairie at Onefour in southeastern Alberta, and 1 in the Palouse Prairie near Kamloops, British Columbia. Yearling Herefords were tested at 3 sites and Hereford cow-calf pairs at 1 Stavely site. At each site, three paddocks radiated from the pond that were stocked with 10 yearlings or cow-calf pairs randomly assigned to either clean water (water delivered to a trough from a well, river, or pond), pond water pumped to a trough (pond(trough)), or direct access into the pond (pond(direct)). The trials were repeated at each site for 3 to 6 years. Observations were made on cattle weight gains, cow backfat thickness, and activity budgets. Fecal samples were analyzed for selected parasites and pathogens. Other experiments were conducted to determine the effects of manure-contaminated water on feed and water consumption and water selection. Calves, with cows drinking clean water, gained 9% more (P < 0.10) weight than those with cows on pond(direct) but cow weight and backfat thickness were not affected. Yearling heifers having access to clean water gained 23% (P = 0.045) and 20% (P = 0.076) more weight than those on pond(direct) and pond(trough), respectively. Cattle avoided water that was contaminated with 0.005% fresh manure by weight when given a choice of clean water. Cattle that had access to clean water spent more time grazing and less time resting than those that were offered pond(trough) or pond(direct). Cattle management must consider water quality together with forage conditions in order to achieve optimal production from rangeland.

. 2001. Effect of salinomycin or monensin on performance and feeding behavior of cattle fed wheat-or barley-based diets. Can. J. Anim. Sci. 81: 253-261. Feeding behavior and growth performance of cattle fed diets containing monensin or salinomycin were assessed in two trials. In trial 1, 36 Hereford × Angus steers (267.7 ± 4.3 kg) were individually fed (n = 12) wheat-based transition and finishing diets containing no ionophore (control, C), 26 mg monensin (M) or 13 mg salinomycin (S) per kg of dietary dry matter (DM). Cattle fed M consumed less than those fed C or S, and their intake was more stable during the transition to the finishing diet. Overall, steers fed M exhibited lower dry matter intake (DMI) (8.0 vs. 9.2 and 9.2 kg d -1 ) and rates of gain (1.21 vs. 1.62 and 1.56 kg d -1 ) than those fed C or S. Cattle fed S required fewer days (93.3) to reach the targeted finish (5 mm backfat) than those fed C or M (105.8 d). Monensin reduced slaughter weight and carcass weights, relative to controls (414.3 vs. 480.5 kg, and 231.2 vs. 245.8 kg, respectively). In trial 2, M (25 ppm) or S (13 ppm) were included in barley-based diets for 72 yearling steers placed in four pens equipped with radio frequency identification systems. Individual bunk attendance patterns were monitored during transition to a finishing diet, during 11 d of limit feeding the finishing diet twice daily (LF2/d), 13 d of limit feeding once daily (LF1/d), and 21 d of feeding once daily to ad libitum intake (AL1/d). Ionophore type did not affect (P > 0.10) DMI, rate of gain or efficiency of feed conversion. Bunk visits were more frequent (P < 0.05) with M than with S during transition and limit-feeding. With M, total daily attendance (TDA) at the bunk during LF1/d and AL1/d, was higher (P < 0.05) than with S, and variability in TDA was lower (P < 0.05) during LF1/d. In the present study, there was no performance advantage in providing S or M in wheat-based finishing diets. Monensin moderated feeding intensity, but this effect may have been strong enough to suppress intake and even reduce gain on the wheat-based diet. . Lors du deuxième essai, on a ajouté du monensin (25 ppm) ou de la salinomycine (13 ppm) à la ration à base d'orge de 72 bouvillons d'un an répartis dans quatre enclos dotés d'un système d'identification radio. On a surveillé les habitudes de chaque animal pendant la période où les mangeoires étaient remplies de la ration de transition puis de finition selon trois régimes : quantité restreinte de la ration de finition servie deux fois par jour pendant 11 jours (RF2/j), quantité restreinte de la ration de finition servie une fois par jour pendant 13 jours (RF1/j) et ration servie à satiété une fois par jour pendant 21 jours (AS1/j). Le type d'ionophore n'affecte pas le CMS (P > 0,10), le gain de poids ni la valorisation des aliments. Les animaux se rendent moins souvent à la mangeoire (P < 0,05) quand les aliments renferment du monensin plutôt que de la salinomycine durant la période de transition et quand il y a restriction de la quan...

Knowledge of the molecular mechanisms that regulate ovine adipogenesis is very limited. MicroRNAs (miRNA) have been reported as one of the regulatory mechanisms of adipogenesis. This study aimed to compare the expression of miRNA related to ovine adipogenesis in different adipose depots and to investigate whether their expression is affected by dietary fatty acid composition. We also investigated the role of miRNA in adipogenic gene regulation. Subcutaneous and visceral adipose tissue samples were collected at slaughter from 12 Canadian Arcott lambs fed a barley-based finishing diet where an algae meal (DHA-Gold; Schizochytrium spp.) replaced flax oil and barley grain at 0 or 3% DM (n = 6). Total RNA from each tissue was subjected to quantitative real time (qRT-) PCR analysis to determine the expression of 15 selected miRNA including 11 identified from bovine adipose tissues and 4 conserved between bovine and ovine species. MicroRNAs were differentially expressed according to diet in each tissue depot (miR-142-5p and miR-376d) in visceral and miR-142-5p, miR92a, and miR-378 in subcutaneous adipose tissue; P ≤ 0.05) and in each tissue depot depending on diet (miR-101, miR-106, miR-136, miR-16b, miR-196a-1, miR-2368*, miR-2454, miR-296, miR-376d, miR-378, and miR-92a in both control and DHA-G diets and miR-478 in control; P ≤ 0.05). Six miRNA were subjected to functional analysis and 3 genes of interest (ACSL1, PPARα, and C/EBPα) were validated by qRT-PCR. Both diet and tissue depot affected expression levels of all 3 genes (P < 0.05). miR-101, miR-106, and miR-136 were negatively correlated with their respective predicted gene targets C/ EBPα, PPARα, and ACSL1 in subcutaneous adipose tissue of lambs fed DHA-G. Yet miR-142-5p and miR-101 showed no correlation with ACSL1 or C/EBPα. The variability in expression patterns of miRNA across adipose depots reflects the tissue specific nature of adipogenic regulation. Although the examined miRNA appear to be conserved across ruminant species, our results indicate the presence of ovine specific regulatory mechanisms that can be influenced by diet.