Evaluation of spray dried animal plasma and calcium formate as alternatives to colistin in piglets experimentally infected with Escherichia coli K99

Two trials were conducted to evaluate spray dried animal plasma and calcium formate as alternatives to preventive medication with colistin in piglets experimentally challenged with Escherichia coli K99. Two groups of newly weaned pigs were offered four treatments consisting of: Negative Control (NC); spray dried animal plasma (SDAP); calcium formate (CF) and colistin (COL). All animals were experimentally challenged with a single oral dose of E. coli K99. Their performance was recorded and, in the second trial, 6 piglets from each treatment were killed to obtain samples of jejunal mucosa for histological measurements and digesta from the ileum and the caecum for microbiological determinations. SDAP improved weight gain (P < 0.05) and feed intake (P < 0.06) in the first two weeks after weaning of trial 1, and a similar response, although not statistically significant, was found in trial 2. Colistin also resulted in a numerical improvement in performance, but calcium formate did not. No clear effects on mucosal histology were observed and only colistin had a significant effect on the microbiological composition of digesta.