Impact of PRRS and PED viruses on grower pig performance and intestinal function

Abstract

Porcine reproductive and respiratory syndrome (PRRSV) and porcine epidemic diarrhea (PEDV) viruses are two of the most economically significant diseases to affect the U.S. swine industry today. Yet, little is known about how they impact pig nutrient digestibility, intestinal function and feed efficiency. Therefore, the overall objective of this thesis was to determine the impact of PRRSV and PEDV viruses, alone or in combination, on grower pig performance, tissue accretion and on intestinal function and integrity. To accomplish these objectives, a series of experiments were conducted and are outlined in three research chapters (Chapter 2, 3 and 4). In Chapter 2, an experiment was conducted using growing pigs to assess the longitudinal impact of PRRSV on growth performance, feed efficiency, tissue accretion and apparent total tract digestibility (ATTD). In Chapter 3 pigs were infected with PRRSV, PEDV or a combination of both, to determine their impact on growth performance, feed efficiency, ATTD and apparent ileal digestibility (AID). The final research chapter (Chapter 4) assessed the effects of PRRS and PED viruses on intestinal integrity and function. The results from this research indicate that PRRSV significantly reduces overall growth performance and feed efficiency. It also reduces ATTD of nutrients and energy in an industry setting (Chapter 2), but did not reduce AID of nutrients (Chapter 3). Expectedly, PRRSV infection did not affect markers of intestinal health and integrity, but did improve active glucose and lysine transport in the jejunum (Chapter 4). Jejunum sucrase activity was also improved during the 21 day PRRSV infection. However, no differences in the gene abundance of nutrient transporters between PRRSV and healthy