Digestion of two legumes and rumen bacterial growth in defaunated sheep

Lindsay, JR; Hogan, JP

doi:10.1071/ar9720321

Cited by 95 publications

(32 citation statements)

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“…The decreased OM digestibility in the whole tract, observed in the present study as a result of defamation, is consistent with the findings of Klopfenstein et al (1966) and Lindsay & Hogan (1972). It appears therefore that while the rate of cellulose degradation in the rumen may actually be increased (Kurihara et al 1978) and total VFA production unchanged (present study) by defaunation, the availability of energy to the animal may be decreased.…”

Section: Defamation Rumen Fermentation and Digestion 117supporting

confidence: 82%

Quantitative effects of defaunation on rumen fermentation and digestion in sheep

1985

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1. Studies on the quantitative significance of protozoa on carbon and nitrogen digestion and metabolism in the rumen were carried out in sheep given a diet of pelleted concentrate (500 g/d) and chopped hay (500 g/d).2. Measurements were made of apparent digestibility; flows of organic matter and dietary and microbial non-ammonia N (NAN) (using 16NH:) to the duodenum; and rates of production, interconversion and metabolism of the major C fermentation end-products (from mathematical modelling of 14C isotope values).3. The population density of bacteria in the rumen increased as a result of defamation (28.6 compared with 8.2 x lo0 organisms/ml). This high density was associated with greater utilization of volatile fatty acids (VFA) within the rumen.4. The rate of irreversible loss (IL) of bicarbonatefcarbon dioxide from the rumen was greater in the defaunated animals (98.5 v. 57.2 g C/d) but the IL from the blood was greater in the faunated group (138.6 v. g C/d). This is consistent with the hypothesis that the high population density of bacteria found in the rumen fluid of defaunated animals may result in increased fermentation of rumen VFA and digestible dietary carbohydrate, thereby increasing the output of CO, from the rumen and reducing the quantity of VFA (hence energy) available to the host.5. There was no difference in the flow of organic matter (OM) to the duodenum but there was a higher faecal excretion of OM in defaunated animals (apparent OM digestibility: 0.72 in faunated, 0.67 in defaunated).6. Defamation did not significantly increase the flow of NAN to the duodenum, the percentage of duodenal NAN of bacterial origin or the quantity of microbial NAN synthesized/g organic matter fermented. Faecal excretion of NAN was higher in defaunated animals (5.3 v. 3.6 g N/d).

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Section: Defamation Rumen Fermentation and Digestion 117supporting

confidence: 82%

Quantitative effects of defaunation on rumen fermentation and digestion in sheep

1985

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“…In addition the engulfment of bacteria by protozoa is likely to reduce further microbial amino acid availability. This study suggests that the 16% increase in protein availability on defamation of sheep observed by Lindsay & Hogan (1972) is likely to be much higher whenever protozoa numbers reach levels similar to those present in the sheep used in the present studies. The suggestion made here of only a small proportion of protozoa present in the rumen moving into the lower digestive tract is well supported by the studies of Dawson et al (1981) who showed that little or no labelling occurs in the blood lipids when sheep are fed on…”

Section: Discussionmentioning

confidence: 72%

“…Part of the apparent inefficiency in microbial cell growth, and therefore availability of microbial protein to the animal, may be attributable to the turnover ofmicrobial cells in the rumen (Nolan & Leng, 1972). The apparent retention of protozoa in the rumen (Weller & Pilgrim, 1974;Minor et al 1977;Bird et al 1978;Harrison et al 1979) and the increased microbial protein flow to the duodenum on defamation of sheep (Lindsay & Hogan, 1972), together with observation of significant quantitative engulfment of bacteria by protozoa (Coleman, 1975), all suggest that a large population of protozoa may lead to a low rate of microbial protein synthesis or flow-rate to the small intestines or both. In addition recent studies of microbial growth in ruminal digesta in vitro have indicated that the presence of protozoa increased the turnover of bacterial cells and this lowered the net yield of microbial protein (Demeyer & Van Nevel, 1979).…”

mentioning

confidence: 99%

Dynamics of protozoa in the rumen of sheep

Leng

1982

Br J Nutr

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1. Protozoa were labelled by incubating 100ml rumen fluid with [14C]choline for 1 h. The protozoa were concentrated by centrifugation and then washed with rumen fluid. This reduced residual I4C in the fluid medium to insignificant amounts while still retaining the viability of the labelled protozoa. Washing procedures using formal saline (40 g formaldehyde/l saline (9 g sodium chloride/l)) and saline were developed to isolate protozoa for estimation of specific radioactivity.2. The protozoal pool in freshly-collected rumen fluid incubated in vitro retained 90% of the radioactivity for up to 6 h following addition of "C-labelled protozoa produced as indicated previously. The specific radioactivity of protozoa did not change during the incubation period.3. Protozoa labelled with [14C]choline and then stored until they died rapidly lost 14C to methane when they were incubated in rumen fluid or were injected into the rumen. Some [14C]choline was salvaged under these conditions by the live protozoa present as they apparently incorporated up to 13% of the label from the dead protozoa. However, protozoal debris from the injected solution could also have been present in the isolated protozoa.4. The in vitro results suggested that the protozoal preparations were viable, and that the incorporated choline did not have a turnover in excess of the turnover of nitrogen (i.e. specific radioactivity remained constant with time in vitro) suggesting that the dilution of specific radioactivity of protozoa following mixing of a 14C-labelled dose of protozoa represented the rate of irreversible loss and also replacement of protozoa in the rumen.5. IT-labelled protozoa had a half-life in the rumen which was greater than that of rumen fluid and in six animals the protozoal replacement rate was 1 4 . 1 mg N/min. 6. Losses of I4C from labelled protozoa in the rumen in methane or via abomasal digesta were 65 and 35% respectively.7. The results suggest that protozoal growth may be as high as 32% of the total microbial protein synthesis in the rumen but that 65% of the protozoa die and are degraded in the rumen.

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“…With forage diets the amount of energy supplied to the rumen micro-organisms is a major factor limiting their growth, some 15-25 g of bacterial protein being synthesised per 100 g of plant organic matter fermented in the rumen (Hogan & Weston 1967, 1971Lindsay & Hogan 1972). Rumen bacteria contain approximately 2.1 g SAA-N per lOOg total N (Hogan & Weston 1971), and the apparent digestibility of this fraction in the intestines of the sheep is approximately 70% (Bird 1972).…”

Section: Factors Affecting the Sulphur (And Cystine) Content Of Wool mentioning

confidence: 99%

Content and retention of sulphur in wool as affected by formaldehyde treatment of the diet, level of energy intake, and intraperitoneal supplementation with DL-methionine

Barry¹,

Andrews²

1973

New Zealand Journal of Agricultural Research

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ABSlRACfYoung Romney sheep were fed indoors in pens in three experiments. Untreated and formaldehyde (HCHO)-treated casein were fed as supplements to a maintenance ration of hay (Experiment 1); untreated hay and two hays treated with HCHO were fed at maintenance and half maintenance levels of energy intake, with and without intraperitoneal supplementation with DL-methionine (Experiment 2); and untreated and HCHO-treated silage were fed ad libitum with and without intraperitoneal supplementation with DL-methionine (Experiment 3).The amount of sulphur retained in wool was increased by HCHO treatment of casein, by increasing the level of casein intake, and by the administration of DL-methionine, due to increases in both the sulphur content and the growth rate of wool. Formaldehyde treatment of hay had no effect on either the sulphur content or the amount of sulphur retained in wool. Increasing the level of hay intake and HCHO treatment of silage (which caused an increase in silage intake) both increased wool sulphur retention, due only to increases in wool growth rate.Th:: proportion of methionine-sulphur recovered in wool was respectively 35% and 45% on the hay and silage diets. This is discussed in relation to the overall efficiency of conversion of absorbed amino acids to wool. It is considered that the failure of IleHO treatment of hay to increase sulphur retention in wool casts doubt on whether the treatment, in this instance, increased the amount of sulphur-containing amino acids available to the sheep. 545

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Digestion of two legumes and rumen bacterial growth in defaunated sheep

Cited by 95 publications

References 0 publications

Quantitative effects of defaunation on rumen fermentation and digestion in sheep

Quantitative effects of defaunation on rumen fermentation and digestion in sheep

Dynamics of protozoa in the rumen of sheep

Content and retention of sulphur in wool as affected by formaldehyde treatment of the diet, level of energy intake, and intraperitoneal supplementation with DL-methionine

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