Bhandari and colleagues at the University of Manitoba evaluated the effect of raw potato starch (RPS) on growth performance, post-weaning diarrhoea and gastrointestinal microbial populations in weaned piglets.

Eighty-four piglets were weaned at 17 ± 2 days of age with an average bodyweight of 6.0 ± 0.9 kg. Pigs were blocked by bodyweight and assigned to one of four diets in a randomised complete block design with seven replicate pens per diet and three pigs per pen. Treatments were:

• a positive control (PC) containing an antibiotic
• a negative control (NC) with no RPS and no antibiotic
• NC + 7 per cent RPS (7% RPS) and
• NC + 14 per cent RPS (14% RPS).

Diets were based on corn, wheat and soybean meal and formulated to meet NRC (1998) recommendations. The average daily gain, average daily feed intake and gain:feed ratio were determined weekly. Faecal consistency scoring was determined daily. After week 3, one pig with a bodyweight closest to the pen mean was killed to evaluate ileal and colonic mucosal-attached Escherichia coli and lactic acid bacteria, as well as digesta pH, volatile fatty acids and and ammonia-nitrogen concentrations. The DNA was extracted from ileum and colon digesta and used for molecular microbial evaluations using terminal-RFLP analysis of 16S rDNA genes.

Average daily gain for week 1 was greater (P<0.01) for the PC diet but diet had no effect on average daily gain during week 3.

Average daily feed intake did not differ among treatments during the first two weeks, and it was lowest for the 7 per cent RPS diet during wee 3.

The NC diet had a greater (P<0.05) faecal consistency score during week 1 than other treatments but diet had no effect on the score during weeks 2 and 3.

Diets had no effect on the colon lactic acid bacterial counts. However, the PC diet had decreased (P<0.05) colon E. coli counts than other treatments.

Ileum and colon digesta pH and total volatile fatty acid concentrations did not differ among treatments. Pigs fed with 7 and 14 per cent RPS diets had greater (P<0.05) ileum ammonia-nitrogen concentration than pigs fed with other diets.

There was more diarrhoea (P<0.05) in the 14% RPS than 7% RPS and control treatments at day 21. This difference correlated with a decline (P<0.05) in microbial diversity in the colon.

The researchers concluded that 7 per cent RPS can be used to prevent post-weaning diarrhoea in weaned piglets but there are no effects on growth performance.

Reference

Bhandari, S.K, C.M. Nyachoti and D.O. Krause. 2009. Raw potato starch in weaned pig diets and its influence on post weaning scours and the molecular microbial ecology of the digestive tract. J. Anim Sci. 2009. 87:984-993. doi:10.2527/jas.2007-0747.