Effect of high canola meal content on growth performance, nutrient digestibility and fecal bacteria in nursery pigs fed either corn or wheat based diets

In North-America, soybean meal (SBM) and canola meal (CM) are the most extensively used protein supplements in the feed industry and corn and wheat are the primary sources of energy in swine diets. Recent studies show that piglets can tolerate relatively high levels of CM inclusion. However, it is unclear whether this ability depends on the cereal ingredient of the basal diet. This study was conducted to examine the effect of including CM in wheat or corn-based diet on growth performance, apparent total tract digestibility (ATTD) and fecal microbial communities compared with wheat- or corn-SBM based diet. Ninety-six pigs (Yorkshire-Landrace x Duroc) with an initial BW of 6.63 +/- 0.028 kg (barrows) and 6.78 +/- 0.036 kg (gilts) were used in this 28-d feeding study. There were 8 replicates per treatment, each with 3 pigs. Pigs were randomly allotted to one of the four dietary treatments: corn-SBM diet (CSBM), corn-SBM diet + 200 g/kg CM (CCM), wheat-SBM diet (WSBM), and wheat-SBM diet + 200 g/kg of CM (WCM). A two-phase feeding program was used (phase I, 1-14 and phase II, 15-28 d post-weaning). Average daily gain (ADG), average daily feed intake (ADFI) and feed efficiency (G:F) were recorded weekly. Freshly voided fecal samples were collected on d 21 and 27 to determine ATTD of CP, energy, and fecal bacteria community. Data were analyzed as a randomized complete block design using the MIXED procedure of SAS and differences were declared significant at P < 0.05. No significant differences were observed in ADFI, ADG, and final-BW among treatments. During phase I, pigs fed the WCM diet had higher G:F compared with those fed the CSBM diet (0.95 vs. 0.79, P < 0.01). During phase II, pigs fed CSBM diet had higher ATTD of CP and energy compared with piglets fed the CCM, WSBM and WCM diets (96.6 vs. 89.0, 90.9 and 87.2%; and, 95.3 vs. 89.6, 90.8 and 86.9%, P < 0.01). When compared to corn-based diets, wheat-based diets had a significant reduction in the relative abundance of Lactobacillus (P < 0.05). Likewise, the relative abundance of Enterococcus was reduced (P < 0.05). However, wheat-based diets had a significantly higher relative abundance of Clostridium cluster-IV (P < 0.05). In conclusion, the inclusion of CM into either wheat- or corn-SBM based diet influences G:F, protein, and energy digestibility and relative abundance of the measured fecal microbial community without affecting voluntary feed intake and body weight gain.