In Vitro Digestion of Bloat-Safe and Bloat-Causing Legumes by Rumen Microorganisms: Gas and Foam Production

Abstract

Leaves of three bloat-safe legumes -- birdsfoot trefoil (Lotus corniculatus L.), sainfoin (Onobrychis viciaefolia Scop.), and cicer milkvetch (Astralagus cicer L.) -- and of three bloat-causing legumes -- alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), and white clover (Trifolium repens L.) -- were incubated with strained rumen fluid or with mixed rumen fluid and solids. Gas released was measured during the early period (0 to 22 h) of this in vitro digestion. Gas volume was greater with a 1:1 (wt/vol) mixture of solid and fluid rumen contents than with rumen fluid alone. It was greater with whole and chewed leaves from the bloat-causing legumes than with whole leaves from the bloat-safe legumes. However, when leaves were homogenized, volumes of gas from bloat-causing and bloat-safe legumes were similar. More gas was released from homogenized leaves than from the same weight of whole leaves. The amount of foam produced on chewed herbage and homogenized leaves of bloat-causing legumes was greater than on those of bloat-safe legumes. These results are consistent with the rate of disintegration and digestion of legumes by rumen bacteria being an important determinant in pasture bloat. Measurement of gas produced early in in vitro digestion may provide a useful bioassay for evaluating the bloat-causing potential of legumes in breeding selections if variability of the method can be reduced.

Influence of nitrogen source on the fermentation of fibre from barley straw and sugarbeet pulp by ruminal micro-organismsin vitro

“…This effect was more pronounced with PEPHIGH treatment, indicating that the stimulation of microbial growth by peptides could be dose-dependent (Atasoglu et al 1998, at least to the higher concentration reached in this experiment. These results are consistent with the greater VFA values observed in the presence of peptides for both substrates, as increases in the VFA have been observed by including particulate microorganisms in the in vitro medium (Fay et al 1980;Senshu et al 1980). In contrast, Carro & Miller (1999) found that the replacement of ammonia by NAN sources (amino acids, peptides and protein) did not increased the amount of SAM in semi-continuous fermenters.…”

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

“…Protein and ADF did not differ between sainfoin and alfalfa hays fed in 1994 however, which suggests against the latter possibility. Fay et al (1980) and Howarth et al (1982) showed that whole-forage ruminal digestibility is lower for sainfoin than for alfalfa. Although in the present study the alfalfa and sainfoin leaves were crushed prior to their introduction into the Rusitec in order to enhance release of soluble cellular constituents (e.g., proteins, CT) and thereby ameliorate the inherent differences in the forages, the disparity in DM digestibilities was not overcome and continued to exert the primary influence on digestibility of diets in the Rusitec.…”

Variation in alien Lotus corniculatus L. 1. Morphological differences between alien and native British plants

“…Our experience with L. corniculatus is, however, more directly comparable with the work of Sheppard (1951) and Sheppard and Cook (1962) There is no doubt that the alien plants both at Etton and at Scawby have morphological characters suitable for agronomic purposes: large leaflets, long stems, erect habit. The agronomic potential of the species in the U.K. has been advocated for many years (e.g., Ellis, 1743;Robinson, 1934), but it is only in the U.S.A. and Canada that any significant progress has been made (McDonald, 1946;Poostchi and MacDonald, 1961;Fay et al, 1980;Lees eta!., 1981). Indeed, Grant and Marten(1984) have evidence that L. corniculatus is now second only to Medicago sativa L. in importance as a forage legume in North America.…”