Cereal and protein sources fed to pigs after weaning influence faecal shedding of β-haemolytic Escherichia coli

Feeding different cereal and (or) protein sources after weaning influences production, the structure and function of the gastrointestinal tract, and the incidence of post-weaning colibacillosis (PWC; Heo et al. 2013). Several studies show that white rice can replace other cereals in nursery diets, and with animal protein sources, can reduce the incidence of PWC (Montagne et al. 2004). However, an imbalance between amounts and (or) types of carbohydrates and proteins entering the large intestine in pigs fed rice-based diets may induce PWC (Pluske et al. 2007). This experiment examined whether feeding a different cereal base (rice or wheat), in combination with sources of animal proteins or vegetable proteins, would influence the excretion of β-haemolytic Escherichia coli and antibiotic treatments given to pigs after weaning.

A total of 84 newly weaned pigs (Large White x Landrace), aged 24 days and weighing 6.7 ± 0.13 kg (mean ± s.e.m.), were used in a 3 × 2 factorial arrangement of treatments with the respective factors being (1) three cereal types (extruded medium-grain rice, extruded long-grain rice, or hammer-milled wheat); and (2) two dietary protein sources (animal v. vegetable). Diets were formulated to contain adequate levels of energy and nutrients for pigs of this genotype and age, and had a crude protein content of 200 g/kg. Pigs were offered their respective diets in groups of four for the first 7 days after weaning, and for the final 2 weeks were housed individually (0.42 m²/pig). Each pen was equipped with a nipple water drinker and a stainless steel feed trough. Pigs were swabbed for the presence or absence of β-haemolytic E. coli upon arrival and then on d 2, 5, 6 and 8 after weaning, and the number of pigs injected with antibiotics for clinical PWC (as assessed by the stockperson) was recorded. Treatment effects were assessed by two-way ANOVA for a factorial design using StatView 5.0 for Windows (AddSoft Pty Ltd, Australia). The results are shown in Table 1.

Table 1.  Interaction means for antibiotic treatments and faecal swab score recorded in pigs after weaning

The number of antibiotic treatments given for clinical PWC after weaning was similar for all treatments (P > 0.05). Feeding vegetable proteins showed a strong tendency to reduce (P = 0.057) faecal shedding of E. coli after weaning compared to pigs fed animal protein sources. This difference was caused predominately by the greater swab score in pigs fed diets with long-grain rice plus animal protein diet (P = 0.069). This suggests feeding this form of rice, which has the most amylose and least amylopectin, in the presence of vegetable proteins reduced ETEC colonisation and subsequent shedding of β-haemolytic E. coli.