The overall hypothesis was that increasing the supplementation of niacin to finishing pigs during periods of heat stress can increase skin vasodilation which will improve heat abatement and result in a pig that exhibits fewer signs of heat stress. The overall goal of this research was to find a dietary means to help mitigate the negative effects associated with seasonal heat stress on pig performance and potentially improve pork quality.

The current study suggests that additional supplementation of niacin above the animal’s requirement (14 mg/lb) does not influence ADG or F/G. It should be noted that the main objective of this experiment was not to evaluate the finishing pig’s niacin requirement, as the increasing levels tested were 12 to 33 times requirement (172, 331, 490 mg/lb) which were selected for heat stress abatement potential and based off of research conducted in other species.

For pork quality, the current study suggests that supplementation of niacin at levels 12 to 330 times above the pig’s niacin requirement does not drastically impact pork quality. This contrasts with previous meat quality research which observed improved color and pH with increasing niacin supplementation up to 249 mg/lb. The reasons for the different findings are currently unknown.

As a primary objective, the study was designed to evaluate the influence of increasing dietary niacin in a heat stressed environment. This experiment was conducted in a commercial research-finishing barn in southwestern Minnesota and started June 13th and ended September 18th, 2013. The barn was naturally ventilated and double-curtain sided with completely slatted flooring and a deep pit for manure storage. The daily average temperature ranged from 63.8 to 85.5 °F and daily average humidity ranged from 44.9 to 85.5%. Unfortunately the barn environmental conditions did not achieve both the expected average and high temperatures and humidity as documented in previous year’s summer months. As a result, the degree of seasonal heat stress observed during this study was less than anticipated which may have influenced the lack of response to increasing dietary niacin. This may also explain why we did not observe consistent treatment differences in pig rectal temperatures as well as shoulder and rump skin temperatures. Within the environmental conditions present at the time this study was conducted, increasing niacin was not effective in mitigating any heat stress that might have been present.

Producer bottom line:
1) Additional niacin above the pig’s requirement does not influence growth, carcass or meat quality.
2) Increasing niacin did not influence pig rectal temperatures or shoulder and rump surface temperatures nor did it ameliorate any other indication of heat stress; however, the amount of heat and humidity present at the time this study was conducted was less than anticipated.
3) Due to the success of niacin to reduce heat stress in other species, specifically dairy cattle, more research is needed in a more adverse heat and humidity environment to fully determine if increasing dietary niacin will impact heat stress of pigs.

Dr. Joel DeRouchey
Kansas State University

Department of Animal Sciences and Industry
222 Weber Hall
Manhattan, KS 66506
Josh Flohr
Kansas State University
Department of Animal Sciences and Industry
217 Weber Hall
Manhattan, KS 66506