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PRRSv reduces feed efficiency and tissue accretion rates in grow-finisher pigs
Porcine reproductive and respiratory syndrome virus (PRRSv) is a major swine virus that causes reproductive impairment in sows, as well as respiratory disease, reduction in growth rates, and increased mortality in all ages of pigs. The objective of this study was to quantify the impact of PRRSv on grow-finisher pig feed efficiency and tissue accretion rates. Thirty PRRSv naïve, littermate pairs of maternal line Choice Genetics gilts (33 ± 3 kg BW) were selected and pairs split across two barns consisting of five pens (n = 6 pigs/pen/barn). Pigs in both barns were fed typical Midwest corn-soybean-DDGS diets. All pigs had ad libitum feed and free access to water. One barn was inoculated (CHAL) via an I.M. injection of a live PRRSv strain isolated from the region (0 days post inoculation, dpi), while pigs in the other barn were given a saline control injection (CONT). Pig performance (ADG, ADFI, GF) in both barns was assessed over an 80 dpi period. Additionally, longitudinal body composition was assessed using Dual-energy X-ray absorptiometry on days -1 and 80 dpi, and lean, protein, fat and bone accretion rates calculated. Serological data showed that the CHAL pigs PRRSv titers peaked 7 dpi and these pigs seroconverted by 35 dpi. According to both genomic and protein PRRSv titers, CONT pigs were naïve to PRRSv throughout the study. Compared to the CONT, CHAL pigs had decreased ADG (0.72 vs. 0.90 kg/d, P < 0.001), ADFI (1.85 vs. 1.98 kg/d, P < 0.001), and GF (0.39 vs. 0.46 kg/d, P < 0.001) over the 80 d test period. Furthermore, CHAL pigs had attenuated whole body lean (547 vs. 633 g/d, P = 0.001), protein (109 vs. 126 g/d, P = 0.001) and fat (169 vs. 205 g/d, P = 0.001) accretion rates compared to their CONT counterparts. The data clearly demonstrate that PRRSv infection reduces feed efficiency and protein accretion rates in grow-finisher pigs. We estimate this to cost producers $6 to $12 per head depending on management style. Supported by the National Pork Board #12-162.
Keywords: PRRSv, tissue accretion