The objective of this study was to investigate the potential of reducing enteric methane production from dairy cows by incorporating into the diet various sources of long-chain FA varying in their degree of saturation and ruminal availability. The experiment was conducted as a crossover design with 16 lactating dairy cows maintained in 2 groups and fed 4 dietary treatments in four 28-d periods. Eight ruminally cannulated primiparous cows (96 +/- 18 d in milk) were assigned to group 1 and 8 multiparous cows (130 +/- 31 d in milk) were assigned to group 2. The dietary treatments were: 1) a commercial source of calcium salts of long-chain fatty acids (CTL), 2) crushed sunflower seeds (SS), 3) crushed flaxseed (FS), and 4) crushed canola seed (CS). The oilseeds added 3.1 to 4.2% fat to the diet (DM basis). All 3 oilseed treatments decreased methane production (g/d) by an average of 13%. When corrected for differences in dry matter intake (DMI), compared with CTL, methane production (g/kg of DM intake) was decreased by feeding FS (-18%) or CS (-16%) and was only numerically decreased (-10%) by feeding SS. However, compared with the CTL, feeding SS or FS lowered digestible DMI by 16 and 9%, respectively, because of lowered digestibility. Thus, only CS lowered methane per unit of digestible DM intake. Feeding SS and CS decreased rumen protozoal counts, but there were no treatment effects on mean ruminal pH or total volatile fatty acid concentration. Milk efficiency (3.5% fat corrected milk/DMI), milk yield, and component yield and concentrations were not affected by oilseed treatments. The study shows that adding sources of long-chain fatty acids to the diet in the form of processed oilseeds can be an effective means of reducing methane emissions. However, for some oilseeds such as SS or FS, the reduction in methane can be at the expense of diet digestibility. The use of crushed CS offers a means of mitigating methane without negatively affecting diet digestibility, and hence, milk production.

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.

. 2007. Effects of essential oils and their components on in vitro rumen microbial fermentation. Can J. Anim. Sci. 87: 413-419. The objective of this study was to investigate the effects of essential oils (EO) and essential oil compounds (EOC) on in vitro rumen microbial fermentation. Treatments were: control (no additive), cinnamon leaf oil (400 mg L -1 ), clove leaf oil (200 mg L -1 ), sweet orange oil (200 mg L -1 ), oregano oil (200 mg L -1 ), thyme oil (200 mg L -1 ), carvacrol (400 mg L -1 ), cinnamaldehyde (400 mg L -1 ), eugenol (800 mg L -1 ), and thymol (400 mg L -1 ). Treatments were evaluated using in vitro 24-h batch culture of rumen fluid with a 51:49 forage:concentrate dairy ration [16.7% crude protein (CP), 34.4% neutral detergent fibre (NDF)]. Incubations were conducted in triplicate with gas production (GP) measured at 0, 2, 6, 8, 12, and 24 h, while pH, ammonia (NH 3 ), volatile fatty acid (VFA), in vitro dry matter (IVDMD) and neutral detergent fibre (IVNDFD) digestibilities were determined after 24 h of incubation. Among the EO and EOC evaluated, only the phenolic compounds, carvacrol, thymol, and eugenol affected ruminal fermentation, relative to the control. Carvacrol (400 mg L -1 ) and eugenol (800 mg L -1 ) increased pH and molar proportion of butyrate, and decreased molar proportion of propionate, IVDMD, IVNDFD, and GP. At the concentration of 200 mg L -1 , thymol increased final pH, and reduced molar proportion of propionate, IVNDFD, and GP. None of the EO or EOC affected NH 3 concentration, suggesting that at the doses tested in this study, protein degradation was not affected by EO and EOC. This study showed that among the EO and EOC investigated only phenolics exhibited antimicrobial activity as exemplified by reduced diet fermentability and a shift in VFA profile from less propionate towards more butyrate. These changes in fermentation may not be nutritionally beneficial to dairy cattle. The present study suggests that the types and concentrations of EO and EOC employed to alter ruminal fermentation must be carefully defined before their widespread use in ruminant nutrition can be recommended. , le thymol a augmenté le pH et a réduit la proportion molaire du propionate, DIVNDF, et GP. La concentration de NH 3 n'a pas été affectée par aucun des traitements évalués, suggérant qu'aux concentrations de HE et CHE évaluées dans cette étude, la dégradation des protéines n'a pas été modifiée. Cette étude a montré que parmi les HE et CHE évaluées, seuls les composés phénoliques ont exercé une activité antimicrobienne telle qu'illustrée par une réduction dans la fementation du substrat et une orientation du faciès fermentaire vers moins de propionate et plus de butyrate. Ce genre de changement dans les fermentations n'est pas nutritionnellement bénéfique pour la vache laitière. Cette étude suggère que le type et les concentrations de HE et CHE utilisées pour modifier les fermentations ruminales doivent être définis avec attention avant qu'ils ne soient recommandés pour utilisation à plus gra...

Two continuous culture (CC) systems, the rumen simulation technique (Rusitec) and a dual-flow (DF) fermenter, were used to evaluate effects of the essential oil from cinnamon leaf (CIN) on rumen microbial fermentation. Incubations (d 1 through 8 for adaptation and d 9 through 16 for sampling) were conducted concurrently in the 2 systems, with CIN added at 0 (control) and 500 mg/L of rumen fluid culture. Eight Rusitec (920 mL; dilution rate = 2.9%/h) and 6 DF (1,300 mL; dilution rate = 6.3%/h) fermenters were randomly assigned to treatment. Inoculum was prepared from 4 ruminally cannulated lactating Holstein cows fed a total mixed ration consisting of 51% forage and 49% concentrate (dry matter basis). Ruminal pH, total volatile fatty acid (VFA) concentration, and diet digestibility were reduced by CIN addition in the Rusitec but were not affected by CIN administration in the DF. The addition of CIN in the Rusitec decreased apparent N disappearance, NH3-N concentration, and molar proportions of branched-chain VFA. In contrast, in the DF no effect of CIN was observed on apparent N degradation, NH3-N concentration, and molar proportion of branched-chain VFA. In the Rusitec, the molar proportion of acetate was similar between treatments on d 9 and 13, but was lower from d 10 to 12 and higher on d 14 to 16 with CIN than with control (interaction of treatment x sampling day). The molar proportion of acetate remained unaffected by CIN addition in the DF. In both CC systems, the molar proportion of propionate was decreased whereas that of butyrate was increased by CIN addition. In the DF, CIN decreased microbial N flow and efficiency of microbial protein synthesis. Protozoa numbers were lower with CIN than with control in both CC fermenters. In the Rusitec, CIN increased 15N enrichment in total bacterial fractions, but no effect was observed on the production of microbial N. This study showed that CIN exhibited antimicrobial activity in both CC systems, but the effects were more pronounced in the Rusitec than in the DF system. These differences are likely a reflection of the higher dilution rate in the DF resulting in a lower effective concentration of CIN than in Rusitec. Based on these changes in rumen microbial fermentation, supplementation of CIN at the concentration evaluated in this study may not be nutritionally beneficial to ruminants.

Over half of US dairy operations use tie-stalls, but these farming systems have received relatively little research attention in terms of stall design and management. The current study tested the effects of the amount of 2 bedding materials, straw and shavings, on dairy cattle lying behavior. The effects of 4 levels of shavings, 3, 9, 15, and 24 kg/stall (experiment 1, n = 12), and high and low levels of straw in 2 separate experiments: 1, 3, 5, and 7 kg/stall (experiment 2, n = 12) and 0.5, 1, 2, and 3 kg/stall (experiment 3, n = 12) were assessed. Treatments were compared using a crossover design with lactating cows housed in tie-stalls fitted with mattresses. Treatments were applied for 1 wk. Total lying time, number of lying bouts, and the length of each lying bout was recorded with data loggers. In experiment 1, cows spent 3 min more lying down for each additional kilogram of shavings (11.0, 11.7, 11.6, and 12.1 +/- 0.24 h/d for 3, 9, 15, and 24 kg/stall shavings, respectively). In experiment 2, cows increased lying time by 12 min for every additional kilogram of straw (11.2, 12.0, 11.8, and 12.4 +/- 0.24 h/d for 1, 3, 5, and 7 kg/stall of straw, respectively). There were no differences in lying behavior among the lower levels of straw tested in experiment 3 (11.7 +/- 0.32 h/d). These results indicated that additional bedding above a scant amount improves cow comfort, as measured by lying time, likely because a well-bedded surface is more compressible.

No abstract

An electronic system has been designed that allows for passive monitoring of feeding behavior of individual cows housed in a free-stall barn. The objective of this study was to validate the data generated by this GrowSafe feed alley monitoring system. Twelve lactating cows were each monitored for 24 h using both the GrowSafe system and time-lapse video. The GrowSafe estimation of number of meals consumed by each cow showed perfect agreement with meal frequency identified using the video recordings. The duration of these meals, as estimated by GrowSafe, was highly correlated with the meal duration derived from the video (R2 = 0.98). Despite the excellent agreement for these meal-based measures, for each cow we found some instances in which the video showed that a cow was present at the feed alley but GrowSafe failed to detect cow presence (12.6% of observations) and a few instances in which the reverse was true (3.5% of observations). However, all the missed or extraneous data from the GrowSafe system were closely associated in time with known periods of feeding. These results indicate that this feed alley monitoring system can provide very good measures of meal frequency and meal duration and reasonable estimates of instantaneous feed alley attendance for loose-housed dairy cattle.

. 2006. A review of research progress on cicer milkvetch (Astragalus cicer L.). Can. J. Plant Sci. 86: 49-62. This review of cicer milkvetch includes both published and unpublished information regarding crop and seed characteristics, seed treatments, breeding, agronomic practices and nutritional value for livestock. Cicer milkvetch is a long-lived perennial, acid-and drought-tolerant crop providing high-quality forage throughout the growing season. It does not cause bloat in ruminants. Although it has caused photosensitization in ruminants, this was apparently due to specific environmental conditions and the cultivar used. Cicer milkvetch is compatible with other forage crops in mixed stands and is particularly suitable for pasture. Although the crop has many good qualities and was introduced in North America approximately 75 yr ago, it has not been utilized extensively, primarily due to slow establishment. However, stand establishment has been improved by elucidation of seed and seedling characteristics, followed by selection for heavy seed, rate of emergence, and mature plant vigor. Improved cultivars, developed through recurrent selection for rapid establishment, are now available. Seed scarification, inoculation with rhizobia, and shallow seeding into a pre-packed, warm seedbed are of great importance in cicer milkvetch establishment. Seeding later in the spring (without a companion crop) increases the probability of successful establishment of genetically improved cultivars. Development of cultivars with upright growth characteristics and long-term persistence under grazing stress, improved scarification techniques (to reduce seed loss), and a seeding protocol for successful establishment of the crop, have the potential to substantially increase utilization of this important forage legume. Cette revue bibliographique englobe l'information connue et inédite sur les caractéristiques de la plante et de la graine, les traitements grainiers, l'hybridation, les pratiques agronomiques et la valeur nutritive de cette culture pour le bétail. L'astragale est une vivace longévive qui tolère bien les sols acides et la sécheresse; elle produit un fourrage de haute qualité pendant toute la période végétative. Elle n'entraîne pas le météorisme chez les ruminants. La photosensibilisation qu'elle engendre à l'occasion chez eux semble résulter de certaines conditions environnementales ainsi que du cultivar employé. L'astragale est compatible avec d'autres plantes fourragères dans les peuplements mixtes et se prête particulièrement bien aux pâturages. En dépit de ses nombreuses qualités et de son introduction en Amérique du Nord il y a près de 75 ans, l'astragale n'est pas énormément utilisée, principalement parce qu'elle prend du temps à s'implanter. On peut néan-moins améliorer l'établissement de la culture en triant les semences et les plantules d'après leurs propriétés puis en sélectionnant les plants pour une production abondante de graines, le taux de levée et la vigueur des plants adultes. On trouve désormais sur le ma...