Comparing the effects of zinc oxide, milk hydrolysate, yeast β glucan and combination of milk hydrolysate / yeast β glucan on growth, gut microbiota and cytokine gene expression in weaning piglets

Abstract Text:

Concerns over the usage of prophylactic antibiotics and pharmacological doses of zinc (ZnO) are driving the need to develop natural sustainable alternatives to support gut health in the piglet during the post weaning period. Our hypothesis was that a diet consisting of a combination of yeast β-glucan (YBG) and sodium caseinate hydrolysate (NaCASH) will improve gut health in weaning piglets and replace the requirement for ZnO in the diet. Thus, the objective of this experiment was to compare the effects of supplementing the weaning piglet diet with ZnO, NaCASH, YBG and a combination of NaCASH + YBG on piglet body weight (BW), gut microbiota and gut cytokine gene expression. Forty 21 d old piglets (7.3 ± 0.2 kg) were weaned and assigned to either: 1) control diet or control diet supplemented with 2) 3.1 g/kg ZnO, 3) 0.25 g/kg NaCASH, 4) 0.25 g/kg YBG or 5) 0.25 g/kg NaCASH + 0.25 g/kg YBG (combination) for 12 days (n=8). Fecal scores per pen were recorded daily and BW recorded on days 0, 6 and 12. Following sacrifice on day 12, caecal and colonic digesta and colonic tissues were collected. Digesta samples were used to enumerate a selected panel of bacterial colonies by 16s rRNA QPCR, while tissue samples were used to evaluate a selected panel of cytokine gene expression by QPCR. Lower fecal scores were recorded in piglets from d 6-12 supplemented with either ZnO (P<0.01) or combination (P<0.05) compared to control group. Similarly, overall ADG, FI and gain to feed ratio were improved in ZnO and combination (P<0.05) groups compared to the control group. However, only ZnO supplementation improved BW (P<0.05) compared to control group. In caecal digesta, Bacteroidetes abundance was increased by ZnO and NaCASH supplementation (P<0.05) compared to control group, whereas YBG group had higher enteropathogenic AEEC compared to control group (P<0.05). In colonic tissues, while IL-1α, IL-1β, IL-8 and IL-17 expression were downregulated in ZnO group, only IL-1α expression was downregulated in NaCASH and combination diet groups compared to control group (P<0.05). Therefore, NaCASH or YBG individually did not improve weaning piglet growth or health, yet in combination they improved growth parameters similar to ZnO supplementation. Hence, these results substantiate our hypothesis that YBG and NaCASH combination could be a suitable alternative to zinc oxide during the weaning period.

Keywords: gastrointestinal tract, post-weaning nutrition, inflammation