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The longitudinal impact of PRRS on metabolism, whole body protein accretion and feed efficiency in grow-finisher pigs
Health challenges in nursery-finisher pig production will significantly affect the economic return for pork producers and is a constant issue our industry faces. While significant advances in molecular and quantitative genetics, clinical diagnostics and virology have been made to enhance our understanding of swine health and important pathogens such as Porcine Reproductive and Respiratory Syndrome virus (PRRS), we are still unsure on how to best feed and manage poor health pigs. By understanding the longitudinal impact PRRS virus and its associated inflammation has on digestibility, metabolism, protein accretion and feed efficiency, insights into nutritional requirements and management strategies can be developed to improve poor-health pig production. Recent data we have generated indicates that PRRS infection alone significantly reduces ADG, ADFI and FE (up to 50%, 32% and 25%, respectively) over the peak viremia and sera conversion periods in gilts, compared to their PRRS naïve littermates. Furthermore, on top of this attenuated feed intake, apparent total tract digestibility of energy and nitrogen were reduced. Intriguingly, these impacts on total tract digestibility may be long lasting, while ADG and ADFI have recovered to comparable to that of healthy pigs. Longitudinal whole body composition analysis also clearly showed that PRRS infection attenuated lean, protein, fat and bone accretion rates, compared to uninfected littermates. These data, together with blood metabolite and hormone analysis, suggests that there is a major catabolic cost, particularly to skeletal muscle, to support the energetic and protein synthesis needs of immune system response. Altogether, this paper will discuss the metabolic and physiological response to PRRS infection and inflammation in grow-finisher pigs and potential nutrition management strategies to support the immune response and recovery.
Keywords: Pig, PRRS, Feed Efficiency, Tissue Accretion