Effects of phosphorus deficiency on rumen microbial activity associated with the solid and liquid phases of a fermentor (Rusitec)

Abstract

Summary. The rumen simulation technique (Rusitec) has been used to study the effects of phosphorus (P) deficiency on bacterial protein synthesis and chemical composition and on adenosine triphosphate (ATP) concentrations in the solid and liquid phases of fermentors. 16 g DM of a P-deficient mixed diet was put into each vessel daily and the vessels were infused with about 1 1 of a P-deficient (0 mg of P) or P-supplemented (120 mg of P/1) buffer. Two vessels per treatment were used, and during a second experimental period the deficient and supplemented buffers were interchanged to determine the effects of P repletion and depletion.The proportion of bacterial N directly incorporated from dietary amino acids or peptides was greater in solid-associated bacteria (SAB) than in liquid-associated bacteria (LAB) (46 vs 19 %). P deficiency increased this proportion in both bacterial populations. Protein synthesis associated with the solid phase represented about 30 % of the total protein synthesis in the system. P deficiency induced a marked decrease in microbial protein synthesis in both phases. Microbial yield declined by about 5 points (g of N/kg OMF) in P-deficient conditions. ATP concentrations were greatly reduced in both phases but P deficiency had no effect on protozoal numbers.The effects of P depletion during period II were similar to those of P deficiency in period I, and P repletion showed that the effects of P deficiency were almost entirely reversible.Introduction.

Effects of fermentable carbohydrates and low dietary phosphorus supply on the chemical composition of faecal bacteria and microbial metabolites in the gastrointestinal tract of pigs

“…This is in agreement with literature data on the composition of rumen bacterial mass (e.g. Komisarczuk et al., 1987; Wider, 2005). For example, the N:P ratio in rumen bacterial mass can be altered by changes in the hay and concentrate levels of the ruminant diet (Martin‐Orúe et al., 1998).…”

“…The results of the present study indicate that the P contents of the MBM, ranging between 13.2 and 23.3 g/kg of DM, are in agreement with data reported for rumen bacteria (6.1-19.9 g/kg of DM) (e.g. Van Nevel and Demeyer, 1977;Komisarczuk et al, 1987;Wider, 2005). Moreover, there is evidence that the chemical composition of rumen bacterial mass depends on the composition of the dietary carbohydrates (Martin-Orú e et al, 1998), which is in agreement with the results of the present study.…”

“…This agrees with observations obtained in rumen bacteria kept under P deficient conditions. Despite a considerable reduction in total microbial protein synthesis in the rumen there was a further increase in bacterial incorporation of N (Komisarczuk et al., 1987). In addition, Dufva et al.…”

Mineral absorption in the black rhinoceros (Diceros bicornis) as compared with the domestic horse

“…One potential explanation could be that Ca needs to be absorbed from the ingesta in the small intestine in large quantities to ensure P availability both in the small intestine and in the hindgut. Phosphorus is a major component of bacterial DM (Ca:P ratio in bacteria is approximately 1:100) (Cerkawski, 1976; Van Nevel and Demeyer, 1977; Merry and McAllan, 1983; Komisarczuk et al., 1987a) and therefore a limiting factor for bacterial growth and action. Low levels of available P can reduce microbial growth, organic matter and cellulose digestibility as well as the production of volatile fatty acids (Breves and Höller, 1987; Komisarczuk et al., 1987a,b) – a major energy source for herbivores.…”

“…Phosphorus is a major component of bacterial DM (Ca:P ratio in bacteria is approximately 1:100) (Cerkawski, 1976; Van Nevel and Demeyer, 1977; Merry and McAllan, 1983; Komisarczuk et al., 1987a) and therefore a limiting factor for bacterial growth and action. Low levels of available P can reduce microbial growth, organic matter and cellulose digestibility as well as the production of volatile fatty acids (Breves and Höller, 1987; Komisarczuk et al., 1987a,b) – a major energy source for herbivores. High intraluminal levels of Ca could, theoretically, render P unavailable through the formation of insoluble Ca–P complexes (Ritskes‐Hoitinga et al., 2004).…”