No abstract

I. Examination of the digesta from all regions of the avian digestive tract showed that volatile fatty acids (VFAs) were present in greatest concentration in the caeca and that they comprised mainly acetic, propionic and butyric acids.2. All droppings contained VFAs but they were present in highest concentration in those of caecal origin. Caecectomy was followed by a marked reduction in the total output of VFAs.3. Birds 14-20 weeks of age had similar concentrations of VFAs along the tract and similar numbers and distribution of micro-organisms. 4. Portal blood contained all the VFAs found in the digestive tract whilst peripheral blood contained only acetic and formic acids.5. The almost complete absence of VFAs from the tract contents of germ-free birds showed that the VFAs normally present in the tract were of microbial origin.6. The presence of similar levels of acetate in the peripheral blood of conventional and germfree birds indicated that circulating acetate was mainly of endogenous and not microbial origin.7. The significance of VFAs as an energy source is discussed.The role of the caeca in the digestive processes of the domestic fowl is generally cansidered to be of little importance, largely because removal of the caeca has no apparent effect on growth rate and performance. There is, however, some evidence that caecectomy leads to much lower digestibility coefficients for the crude fibre of wheat and maize; Halnan (1949) and more recently Thornburn & Willcox (1965) have demonstrated that caecectomy of young cockerels is followed by a reduction in droppings dry matter and overall food digestibility. Cellulose digestibility in a given bird was lowered but the effect was not always evident between one bird and another, a finding explained on the basis of differences in the caecal flora of individual birds.The fermentative abilities of the caecal flora have, in fact, been recognized for many years, although surprisingly little is known about their metabolic activities or of the fate of the end-products. Beattie & Shrimpton (1958) were able to show that the microbial activities in the caeca were essentially fermentative. The occurrence of volatile fatty acids (VFAs) was demonstrated (Shrimpton, 1963) and it was subsequently reported that strains of bacteroides in the caeca fermented glucose with the production of acetic and propionic acids (Shrimpton & Stevens, 1965). We have confirmed and extended these observations on caecal VFAs and demonstrated their absorption into the portal system as a preliminary to an evaluation of their significance as an energy source to the fowl. E X P E R I M E N T A LEighteen in-lay New Hampshire x Light Sussex hens and ten Light Sussex cocks, 24 weeks of age, were used during this investigation. They were housed in individual cages and received a standard commercial diet ad lib. (Complete Lay-feed pellets or https://www.cambridge.org/core/terms. https://doi

No abstract

Eleven species of lactic acid bacteria when grown on a milk‐based medium reduced the pH value to < 4.7. The cells of nine of these species inhibited the growth of Escherichia coli on agar in Petri dishes. However, only Streptococcus faecium and Lactobacillus bulgaricus gave significant cell free anti‐E. coli activity. Activity against E. coli enterotoxin was also found only in two species. L. bulgaricus and S. faecalis. Part of the activity in the former species was cell free. Further investigation of the cell‐free anti‐enterotoxic activity from L. bulgaricus showed that it had a low molecular weight probably < 103, was not very stable and was independent of the anti‐E. coli activity. Broths containing L. bulgaricus fermented to produce high levels of antienterotoxin were beneficial when added to diets for early weaned pigs. It was inferred that this effect was likely to be caused by the anti‐enterotoxic activity.

The studies currently reported formed part of an enquiry whose overall objective was to identify a suitable animal model upon which initial screening of compounds and formulations with prophylactic and/or therapeutic potential in periodontitis could be carried out. An earlier study (Rovin et al. 1966) reported that periodontal inflammation could be produced in the conventional laboratory rat by application of a ligature to the molar teeth. The present paper describes the pathological and histo-pathological changes in the periodontium following application of ligatures to the molar teeth of young rats, and the tissue responses observed after topical application of chlorhexidine digluconate. Plaque formed rapidly and an acute periodontitis was induced; application of increasing concentrations of chlorhexidine digluconate gave a progressive diminution in the severity of the lesions. The major bacterial components of the plaque were actinomycetes and streptococci.