Effect of dietary threonine supplementation on growth performance and diarrhoea in weaned pigs

Abstract

A large proportion of antibiotics applied in pig production is used to treat diarrhoea around 2 to 7 weeks post-weaning (PW). Nutritional strategies to prevent diarrhoea in this period are needed if the antibiotic consumption is to be lowered, and additional threonine (Thr) may be one of such strategies. The objective of this study was to test the effect of five levels of dietary Thr on faecal score (diarrhoea) and growth performance day 21 to 32 PW under commercial conditions. The study was part of a larger quadratic surface response trial with 25 treatment groups. A total of 7,952 piglets, weaned approximately at 28 days of age (average body weight (BW) 7.2 kg ± 0.1), were randomly assigned to one of 25 treatment groups, from two weeks PW to 30 kg BW in a balanced incomplete block design. The five Thr levels represented 87%, 100%, 112%, 125% and 137% of the Danish recommended level of Thr for pigs in this weight interval. At 30 kg BW, there were no differences (P > 0.10) in average daily feed intake (ADFI) between the five levels of Thr, whereas average daily gain (ADG) and feed conversion ratio (FCR) were both affected by Thr level (P < 0.05). Piglets receiving 87% of the recommended Thr supply had lower ADG (479 vs. 505–509 g/day) and a higher FCR (1.70 vs. 1.64–1.65 g feed/g growth) compared to pigs receiving the four higher Thr levels. The probability of diarrhoea, defined as a faecal score 3 or 4, was unaffected (P > 0.10) by Thr level at day 21 to 32 PW. Across Thr levels, the probability of diarrhoea was high (25.7% and 26.1%) at day 21 and 25 PW, and decreased with 10.9 percent units at day 28 PW (P = 0.01). There was no difference (P = 0.83) in diarrhoea probability between day 28 and 32. In conclusion, increasing the dietary Thr levels to 110%-140% of the Danish recommendation did not reduce the probability of diarrhoea from day 21–32 PW on a commercial pig farm.