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I M ROBINSON

Publications and source records attributed to I M ROBINSON.

8 recordsLinked to original sources
PubMed1962

Some nutritional characteristics of predominant culturable ruminal bacteria.

Bryant, M. P. (U.S. Department of Agriculture, Beltsville, Md.) and I. M. Robinson. Some nutritional characteristics of predominant culturable ruminal bacteria. J. Bacteriol. 84:605-614. 1962.-The effect of enzymatic hydrolysate of casein, NH(4) (+), a mixture of volatile fatty acids (acetic, n-valeric, isovaleric, 2-methylbutyric, and isobutyric), hemin, and ruminal fluid on growth of 89 freshly isolated strains of predominant culturable ruminal bacteria was studied, using basal media containing glucose, cellobiose, or maltose as energy source, minerals, cysteine, and S(=) as reducing agents, and H(2)CO(3)-HCO(3) (-) buffer. Of these strains, 13% (four morphological groups) grew poorly or not at all in defined medium plus casein hydrolysate; 6% (one morphological group) required casein hydrolysate; 56% (four morphological groups) grew with either NH(4) (+) or casein hydrolysate as the main source of nitrogen; and NH(4) (+), but not casein hydrolysate, was essential for 25% of the strains (five morphological groups). The volatile fatty acid mixture excluding acetate was essential for 19% of the strains (five morphological groups), and this mixture and acetate were necessary for good growth of 23% of the strains (one morphological group) when casein hydrolysate was excluded from the medium; 30% of the strains (one morphological group) required hemin. Similar studies are reported on 35 old laboratory strains of ruminal bacteria, most of which were previously identified. The results indicate that most strains of ruminal bacteria can be grown in defined media, and suggest the relative importance of NH(4) (+) and volatile fatty acids and the relative lack of importance of organic nitrogen compounds such as amino acids in the nutrition of these bacteria.

Amino Acids↗
PubMed1961

A note on the flora and fauna in the rumen of steers fed a feedlot bloat-provoking ration and the effect of penicillin.

A study was made of the predominant culturable bacteria and ciliate protozoa present in the rumen of two steers that were regularly bloating on a pelleted ratio containing 22% alfalfa meal, 16% soybean oil meal, 61% barley, and 1% common salt. The ruminal microorganisms in the two animals differed as indicated by a high total culture count of bacteria, an almost complete absence of ciliate protozoa, a low pH, and a difference in the proportions of presumptively identified predominant bacterial groups in one animal (steer 26) as compared with the other (steer 32). The first exposure of the animals to procaine penicillin (75 or 150 mg per day on 2 successive days) resulted in an abnormal ruminal flora 31 hr after the first treatment as indicated by drastic drops in total and cellulolytic bacterial counts and a change in the proportions of predominant bacterial groups. The animals refused feed for 32 to 48 hr after the first treatment. After feed consumption resumed, further treatment with 75 mg penicillin on 4 successive days did not appear to greatly alter the flora and did not result in feed refusal in animal 32. In animal 26, amounts of penicillin progressing from 50 to 200 mg per day did not result in feed refusals and observations on rumen ingesta samples during this period indicated a decrease in total bacterial count, a great increase in numbers of ciliate protozoa, a higher pH, and a change in the proportions of predominant bacterial groups so that the ruminal picture was much more similar to that of animal 32 than to its own during the pre-penicillin period. Bloat was not relieved except during the period of feed refusal. The results indicate that the ruminal flora rapidly adapts to penicillin and that bloat of the feedlot type can occur in animals with widely differing numbers and kinds of bacteria and protozoa. Feedlot bloat does not appear to be correlated with the occurrence or numbers of any of the individual predominant groups of bacteria cultured.

Animals↗