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. 1999. Effect of sainfoin on in vitro digestion of fresh alfalfa and bloat in steers. Can. J. Anim. Sci. 79: 203-212. The effects of sainfoin (Onobrychis viciifolia) on digestion of alfalfa (Medicago sativa) were investigated in vitro and in vivo. Fresh alfalfa and sainfoin were incubated in an artificial rumen (Rusitec) in ratios of 100:0, 75:25, 50:50, 25:75 and 0:100 (as-fed). Disappearances of dry matter and N from sainfoin were 77 and 65% of those from alfalfa, respectively. Protease and endoglucanase activities, NH 3 -N and methane production declined (P < 0.05) as sainfoin increased. Bacterial numbers and microbial outputs were unchanged (P > 0.05), but cells incorporated more 15 NH 3 N as sainfoin in the diet increased. Chopped leaves (100:0, 95:5 and 90:10 alfalfa:sainfoin) were incubated for 48 h with diluted ruminal fluid containing 0 or 50 mg polyethylene glycol, which binds tannins. Gas and volatile fatty acid productions were similar (P > 0.05) across treatments, but including 10% sainfoin (without polyethylene glycol) reduced (P < 0.05) NH 3 concentrations between 8 and 24 h. Sainfoin tannins reduced degradation of forage protein without affecting the digestibility of the nonprotein fraction. Alfalfa herbage was fed alone or with early-to full-bloom sainfoin herbage (at 10 or 20% of ad libitum alfalfa dry matter intake) or with sainfoin hay or pellets, to eight Jersey steers in crossover trials conducted over 4 yr. Including sainfoin in the diet reduced (P < 0.001) the incidence of bloat by 45 to 93% in 3 of 4 yr, irrespective of the form in which it was supplied. Co-feeding sainfoin can markedly reduce the incidence of bloat in ruminants consuming fresh alfalfa. De l'herbage de sainfoin et de luzerne étaient mis à incuber dans un rumen artificiel (Rusitec) dans les proportions, en l'état, de 100:0, 75:25, 50:50, 25:75 et 0:100. La digestibilité apparente de la m.s. et du N du sainfoin correspondait, respectivement, à 77 % et 65 % des valeurs obtenues pour la luzerne. Les activités de la protéase et de l'endoglucanase de même que la production de N ammoniacal et de méthane diminuaient (P < 0,05) à mesure qu'augmentait la proportion de sainfoin. Par ailleurs, les numérations bactériennes et les apports microbiens restaient inchangés (P > 0,05), mais les cellules microbiennes incorporaient plus de 15 NH 3 -N. Des feuilles hachées (100:0, 95:0 et 90:10 luzerne:sainfoin) étaient mises à incuber pendant 48 h en présence de liquide ruminal dilué contenant 0 ou 50 mg de polyéthylène glycol (PEG), substance qui a pour effet de lier les tanins. Les productions de gaz et d'AGL étaient du même ordre (P > 0,05) d'un traitement à l'autre, mais l'inclusion de 10 % de sainfoin, sans PEG avait pour effet de réduire (P < 0,05) les concentrations de NH 3 entre 8 et 24 h. Les tanins du sainfoin diminuaient la dégradation des protéines du fourrage, sans toutefois altérer la digestibilité de la fraction non protéique. Nous avons aussi servi pendant 4 ans à 8 bouvillons de la luzerne, seule ou combinée, soit à du sain...

Results from two decades (1973-1993) of bloat research at Kamloops are reviewed. The trials were conducted with groups of ruminally fistulated cattle either grazing or fed daily fresh-cut alfalfa (Medicago sativa) herbage. Studies were conducted during the growing season (May to September) and in the fall (October and November). The alfalfa was usually in the vegetative to early bloom stages of growth. Visual assessments of bloat severity on a scale of 1 to 5 were made .5 to 2 h after feeding started, at which time ruminal cannulas were opened to relieve ruminal pressure. Every cultivar of alfalfa tested caused bloat, but sainfoin (Onobrychis viciifolia), birdsfoot trefoil (Lotus corniculatus), and cicer milkvetch (Astragalus cicer) did not. This confirms the bloat-safe features of these alternate legume forages. Bloat was positively associated with the level of Fraction 1 protein and total soluble protein in alfalfa, supporting the concept of a decreased probability of bloat with advancing stages of plant maturity. There was no association between alfalfa saponins and bloat. Prefeeding ruminal chlorophyll levels were higher and ruminal clearance rates were lower in cattle that were susceptible to bloat. Cattle that bloated on a given day consumed 18 to 25% less alfalfa immediately before bloat than non-bloaters did in the same time period. Ruminal cations were associated with bloat incidence but cation manipulation through supplementation did not prevent bloat. Of all the feed additives tested, only poloxalene (Bloat Guard) completely prevented bloat.(ABSTRACT TRUNCATED AT 250 WORDS)

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