The efficacy of halofuginone lactate against natural Cryptosporidium parvum infection in 150 neonatal market calves of a mixed Belgian breed was tested. The drug was administered orally in the milk replacer over a period of 3 to 14 days at doses ranging from 30 to 500 micrograms/kg of body weight. Over a period of 4 weeks, the animals were examined twice a week for shedding of C. parvum oocysts and were scored semiquantitatively for diarrhea. Weight gain was assessed after 2 and 4 weeks. Subclinical infections by rota-, corona-, and bovine picobirnaviruses were equally distributed in the different groups. In total, 93% of the unmedicated calves eliminated C. parvum within 10 days after arrival at the rearing unit and 62% of them showed diarrhea. Immediately after treatment with halofuginone was started, no more signs of Cryptosporidium-associated diarrhea were established. From the level of 60 micrograms/kg on, oocysts were no longer detected in 98% of animals 5 to 6 days after the start of treatment. Animals remained negative for at least 7 days after withdrawal of the drug. From 7 to 10 days after withdrawal, some animals excreted oocysts again. The number of shedders was closely linked with increasing doses of the drug, which indicates that lower doses do not interrupt infection completely and allow development of immunity. In this respect, a dose of 60 to 125 micrograms/kg over a period of 7 days seems most appropriate in practice. Toxic side effects were noticed only at 500 micrograms/kg.

SEVERAL enteritis/enterotoxaemia syndromes in mammals and birds are the consequence of an uncontrolled overgrowth of Clostridium perfringens invading the small intestine from the caecum and the colon and producing different exotoxins. In suckling beef calves the α, or CPA, and β2, or CPB2, major toxins act in synergy to produce intestinal necrohaemorrhagic lesions. The CPA toxin subsequently transfers into the bloodstream and reaches the brain, causing sudden death

No abstract

Young calves were vaccinated with belgian foot-and-mouth disease (FMD) vaccine and revaccinated with either the same vaccine or with a foreign FMD vaccine. There was a significant serological response to the primary vaccine strains after the first vaccination which was greater following revaccination. At one and two months after revaccination there was no significant difference between the responses to revaccination with vaccine identical to the primary vaccine or with the foreign FMD vaccine. It was concluded that revaccination of young calves is effective even with an FMD vaccine different from the primary vaccine.

Young weaned calves are susceptible to viral and bacterial infections. In two studies 279 and 500 weaned calves were injected at random with an adjuvant, with saline or were left untreated in order to evaluate their weight gain or illness and mortality during the first 10 weeks of fattening on a fat-stock farm. However, in contrast to studies reported in the literature, no significantly higher increase in weight gain and no significant improvement of illness and mortality were found with adjuvant treatment.