Pasture management strategies for reducing the risk of legume bloat in cattle

Abstract

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)

Grazing lucerne as fattening management for young bulls: technical and economic performance and diet authentication

“…This increased performance was a result both of a greater energy intake and a 14% higher efficiency in this phase, which agrees with other studies comparing restricted-realimented v. continuously grown animals (Ellenberger et al, 1989;Hornick et al, 2000). The low incidence of bloat in this study is in accordance with the review of Majak et al (1995), who concluded that the risk of bloat was low when cattle grazed on lucerne continuously.…”

Effect of sainfoin on in vitro digestion of fresh alfalfa and bloat in steers

“…Ruminally fistulated 5-to 8-yr-old Jersey steers were confined in groups (usually with four steers per pen) and were fed fresh alfalfa herbage, with and without sainfoin, at 08:00 h daily. Ruminal cannulae of all steers were opened at least once daily, approximately 1.5 h after feeding, for assessment of severity of bloat as described by Majak et al (1995). One or more occurrences of bloat scoring 3 or higher in the same steer on a given day were recorded as a single animal-day of bloat.…”

“…When necessary, ruminal venting was used to relieve ruminal distension and/or distress in steers exhibiting multiple bloats on a given day. Crossover periods were continued until at least 24 incidents of bloat were observed (Majak et al 1995). Comparisons of the effects of sainfoin on the occurrence of bloat were made using Cochran's Q test (Cochran 1950).…”

The effect of feeding hay before fresh alfalfa on the occurrence of frothy bloat in cattle

“…It should be noted that unlike continuous grazing, feeding in confinement is a much more vigorous test of a treatment owing to the higher incidence of bloat (Majak et al 2001). The length of each period of the crossover trial continued until the sum of the cases of bloat reached a minimum of 24 (Majak et al 1995). Between periods, cattle were fed alfalfa hay for at least 1 d. Animals were cared for under the guidelines of the Canadian Council on Animal Care.…”

“…Ruminal cannulae of all steers were opened at least once daily beginning approximately 0.75 to 2.0 h after feeding began, to assess the severity of bloat as described by Majak et al (1995). The average feeding time was approximately 6 h head…”