Supplementation with a Blend of Capsicum and Artificial Sweetener As a Strategy to Mitigate the Negative Heat Stress Effects on Pig Growth Performance and Intestinal Physiology

Pigs exposed to elevated ambient temperatures exhibit reduced average daily gain, alterations in muscle and fat deposition during growth phases, and decreased overall health. Negative aspects of gastrointestinal (GI) function, integrity and permeability also result from hyperthermia. Artificial sweeteners have the potential to ameliorate the negative effects of heat stress (HS) by increasing GI glucagon-like peptide (GLP)-2 production while capsicum oleoresin has been shown to reduce inflammatory response. Study objectives were to examine the effects of a blend of an artificial sweetener and capsicum oleoresin (CAPS-SUC) on growth performance of pigs. Forty-eight pigs (12 weeks of age, 47.3 kg ± 7.6kg) were assigned to six treatments: thermoneutral conditions (21°C) fed ad libitum with (TN+) or without supplement (TN-), heat stress (35°C) fed ad libitum with (HS+) or without supplement (HS-), and thermoneutral conditions pair-fed to HS intake with (PFTN+) or without supplement (PFTN-). Dietary supplementation began 2 days prior to the 3-day environmental treatment period. Body weight was recorded on day -1 and day 3 relative to start of environmental treatment. Body temperature (BT) and respiration rate (RR) were measured thrice daily and feed intake (FI) were recorded daily. Blood samples were collected on day -1 and day 3 to determine metabolite profiles and complete blood count. Following sacrifice, duodenum, ileum, and colon sections were collected for histology. Pigs in HS conditions exhibited increased BT and RR (~2.7-fold) compared to TN and PFTN groups (P<0.01). Irrespective of day, HS+ animals had increased RR when compared to HS- animals (P<0.04). Heat stress decreased FI compared to TN. Regardless of environmental treatment, supplement with CAPS-SUC increased feed efficiency by 0.12kg (P<0.04); in addition, glucose concentrations in the circulation tended to decrease in CAPS-SUC vs. non-supplemented animals (P=0.1). Insulin concentrations in the circulation increased in HS compared to PFTN (P<0.04), but did not differ from TN so was likely linked to altered feed intake. Similarly, monocyte count increased during HS compared to PFTN (P=0.01), but HS and TN did not differ. Lymphocyte count tended to be decreased in HS compared to PFTN and TN (P=0.052). CAPS-SUC increased basophil count (P<0.03), irrespective of environmental treatment. Ileal villus height tended to decrease during HS and PFTN compared to TN (P<0.08), indicating an effect of intake. Duodenal and colon villus height and duodenal, ileal and colon crypt depth did not differ between groups. Overall, CAPS-SUC supplementation increases pig feed efficiency and may improve immune response.