The effect of Lactococcus lactis-produced Epidermal Growth Factor on the Growth and Intestine Development of Early-Weaned Pigs
The transition of weaning is one of the most crucial periods for the development of piglets. Diets offered to piglets at weaning can have a significant effect on the ease of this transition, as well as growth performance in the weeks following. Epidermal growth factor (EGF) is a peptide found in the sows’ milk that plays a major role in the development of pigs. In this thesis, research is reported investigating the effects of incorporating EGF producing Lactococcus lactis (EGF-LL) and its fermentation products into weaned piglet diets on their growth performance and intestinal development. When EGF-LL culture was incorporated into diets with and without blood plasma, EGF-LL only increased growth of piglets not receiving blood plasma, but their growth performance equaled that of piglets receiving blood plasma. This supplementation also increased jejunal alkaline phosphatase activity in piglets not receiving blood plasma. Second, the effectiveness of including the supernatant of the EGF-LL fermentation into piglet diets was investigated. Piglets receiving the supernatant showed increased growth performance and feed efficiency compared to pigs receiving EGF-LL containing fermentation product and controls. They also had increased levels of jejunal sucrase, and increased relative trefoil factor 3 expression after eight days of treatment compared to controls. To understand the mechanisms behind improved growth and intestine development stimulated by EGF, the dynamics of intestinal gene expression was evaluated from birth to 6 weeks of age, and subsequently, how EGF treatment alters this expression. Increases in mucin 2, keratinocyte growth factor, and interleukin-13 gene expression were observed in EGF treated piglets. The later is consistent with the observed increased goblet cell count. EGF treatment also lead to increased sodium-glucose linked transporter 1 and glucagon-like peptide 2 (GLP2) receptor gene expression, which could support increased glucose absorption, enhanced response to GLP2 (an intestinal growth promoter) and increased villi height. The results presented in this thesis suggest that feeding early-weaned pigs EGF containing supernatant improves growth performance in the weeks following weaning, and that this performance is associated with alterations in jejunal morphology, physiology, and gene expression which improve the piglets ability to digest, transport, and utilize nutrients.