Solid feed provision reduces fecal clostridial excretion in veal calves

Enterotoxemia is characterized by a highly fatal hemorrhagic enteritis in cattle, caused by Clostridium perfringens. Production systems with intensive feeding, such as the veal industry, are predisposed. The primary objective of this study was to determine the effect of solid feed provision on fecal C. perfringens excretion in veal calves. Ten Holstein Friesian bull veal calves were randomly assigned to one of two test diets. Group 1 received solemnly milk replacer twice daily, while group 2 received milk replacer and a maximum of 300g solid feed/day, consisting of a mixture of 30% barley, 30% corn, 30% hulled wheat and 10% chopped straw. The number of C. perfringens per g feces or fecal clostridial counts (FCC) were determined for all calves. Mean FCC were significantly lower in the calves fed milk replacer and solid feed, than in the calves fed solemnly milk replacer. Although the correlation between FCC and enterotoxemia risk remains to be determined, the provision of solid feed to veal calves reduced clostridial excretion, which might contribute to the prevention of this disease.

Non-toxic perfringolysin O and α-toxin derivatives as potential vaccine candidates against bovine necrohaemorrhagic enteritis

Bovine necrohaemorrhagic enteritis is a fatal Clostridium perfringens type A-induced disease that is characterised by sudden death. Recently the involvement of perfringolysin O and α-toxin in the development of necrohaemorrhagic lesions in the gut of calves was suggested, and thus derivatives of these toxins are potentially suitable as vaccine antigens. In the current study, the perfringolysin O derivative PFO^L491D, alone or in combination with α-toxin derivative GST-cpa_247-370, was evaluated as possible vaccine candidate, using in vitro assays. PFO^L491D showed no haemolytic effect on horse red blood cells and no cytotoxic effect on bovine endothelial cells. Furthermore, calves immunised with PFO^L491D raised antibodies against perfringolysin O that could inhibit the perfringolysin O-associated haemolytic activity on horse red blood cells. Antisera from calves immunised with PFO^L491D had a significantly higher neutralising capacity against the cytotoxic effect of C. perfringens culture supernatant to bovine endothelial cells than serum from control calves (P <0.05). Immunisation of calves with PFO^L491D in combination with GST-cpa_247-370 elicited antibodies against perfringolysin O and α-toxin and consequently inhibited both the perfringolysin O-associated haemolytic activity and the α-toxin-associated lecithinase activity in vitro. Additionally, the neutralising ability of these antisera on the cytotoxic effect of C. perfringens culture supernatant to bovine endothelial cells was significantly higher than that from calves immunised with PFO^L491D (P <0.001). In conclusion, perfringolysin O derivative PFO^L491D is an immunogenic antigen that can potentially be used to produce vaccine against bovine necrohaemorrhagic enteritis. Including α-toxin derivative GST-cpa_247-370 has an additional protective effect and therefore vaccination of calves with a combination of both antigens seems even more promising.

Gastro-intestinale Clostridium perfringens-infecties: een blijvend gevaar in de Belgische rundveehouderij

De intensivering van de moderne landbouw wordt geassocieerd met een toename van Clostridium perfringens-gerelateerde, gastro-intestinale problemen bij intensief gevoede runderen, zoals “hemorrhagic bowel disease” bij hoogproductief melkvee en enterotoxemie bij kalveren. Waar de pathogenese van hemorrhagic bowel disease nog grotendeels ongekend is, werden er de laatste jaren nieuwe inzichten in de pathogenese van enterotoxemie bekomen die een belangrijke repercussie op de aanpak van deze ziekte onder praktijkomstandigheden hebben. Ook andere clostridiumgeassocieerde maagdarminfecties, zoals “overeating disease” en neonatale clostridiose, worden regelmatig gediagnosticeerd. Overvoedering met structuurarme, eiwitrijke voeders is een overkoepelende risicofactor bij zowel HBD, enterotoxemie als overeating disease. Een goed uitgebalanceerd dieet dat zo stabiel mogelijk gehouden wordt, is dan ook het belangrijkste aandachtspunt op bedrijven die problemen hebben met clostridiose. Daarnaast dient bij jonge kalveren voldoende aandacht gegeven te worden aan een correcte en hygiënische biestverstrekking om problemen met neonatale clostridiose te vermijden.

Intestinal clostridial counts have no diagnostic value in the diagnosis of enterotoxaemia in veal calves

Enterotoxaemia is an important cause of sudden death in veal calves. This study aimed to evaluate intestinal Clostridium perfringens counts as a diagnostic tool for enterotoxaemia. Field necropsies were conducted on 48 sudden death cases in Belgian Blue veal farms. In 31/48 suddenly deceased calves, the diagnosis of enterotoxaemia was made based on haemorrhagic lesions in the small intestines, while in seven of these cases, no clear-cut diagnosis could be made based on macroscopic appearance of the gut. In the 10 remaining calves, a definitive cause of death other than enterotoxaemia could be identified. Samples of the intestinal content were taken for quantification of C perfringens. After matching cases and controls for diet, and the interval between death and sampling, no significant differences could be detected between the mean C perfringens counts of the small intestines in enterotoxaemia cases and counts in the matching segments in the control group. These results indicate that intestinal C perfringens counts cannot be advised as a discriminative postmortem diagnostic tool for enterotoxaemia in veal calves, not even when sampled within three hours after death.