Dietary level of fibre and age at weaning affect the proliferation of Clostridium perfringens in the caecum, the incidence of Epizootic Rabbit Enteropathy and the performance of fattening rabbits

An experiment was conducted to investigate the effects of dietary fibre content and weaning age on Clostridium perfringens proliferation in the caecum and fattening mortality in growing rabbits farmed in a facility having Epizootic Rabbit Enteropathy. The experiment consisted in a 2 × 2 factorial arrangement with two weaning ages (28 days vs. 42 days) and two levels of dietary neutral detergent fibre assayed with a heat stable amylase and expressed exclusive of residual ash (aNDFom; 330 g/kg vs. 425 g/kg). Controls were made during two consecutive experimental periods that differed in hygienic environmental conditions by modifying the intensity of cleaning and disinfection in the farm previous to the trial. An interaction (P<0.001) was detected among the independent variables studied on Cl. perfringens enumeration in the caecal contents, as minimal values for this trait were obtained in non-medicated animals reared in a clean environment, and especially when they were weaned at a later age and fed the diet with the lower fibre content. The treatments studied also led to a variation in fattening mortality (from 4.7% to 34.0%), which was highly and positively correlated (P<0.001) to the average Cl. perfringens caecal counts in each combination of treatments. The results of the current study indicate that high counts of Cl. perfringens in the caecum can be used as an indicator of Epizootic Rabbit Enteropathy, and suggest that strategies designed to control its proliferation in the caecum might help to limit fattening mortality in rabbit fed diets not-medicated with antibiotics.     

Protein metabolism. 3. Relationship between albumin metabolism and elevated liver protein synthesis in the guinea pig infected with Trichostrongylus colubriformis

Studies of the incorporation of ¹⁴C-l-leucine into polypeptides by isolated liver ribosomes from guinea pigs confirmed previous in vivo studies that showed that Trichostrongylus colubriformis infection results in an elevated hepatic protein synthesis.The increased rate of protein synthesis was associated with the membrane-bound ribosomes that synthesize the circulating plasma proteins. Inappetance of infected animals was not resposible for the increased rate of synthesis by the membrane-bound ribosomes, but it was found that undernourishment may stimulate synthesis by free ribosomes.Plasma albumin turnover rate and loss into the intestine were both significantly increased in infected guinea pigs. It was concluded that these changes stimulated protein synthesis by membrane-bound ribosomes.The importance of elevated liver protein synthesis and loss of plasma protein in gastrointestinal nematode infections is discussed.