Abstract
The objective of this study was to extract novel phenotypes related to disease resilience using daily feed intake data from growing pigs under a multifactorial natural disease challenge that was designed to mimic a commercial environment with high disease pressure to maximize expression of resilience. Data used were the first 1,341 crossbred wean-to-finish pigs from a research facility in Québec, Canada. The natural challenge was established under careful veterinary oversight by seeding the facility with diseased pigs from local health-challenged farms, targeting various viral and bacterial diseases, and maintaining disease pressure by entering batches of 60–75 pigs in a continuous flow system. Feed intake (FI) is sensitive to disease, as pigs tend to eat less when they become ill. Four phenotypes were extracted from the individual daily FI data during finishing as novel measures of resilience. The first two were daily variability in FI or FI duration, quantified by the root mean square error (RMSE) from the within individual regressions of FI or duration at the feeder (DUR) on age (RMSEFI and RMSEDUR). The other two were the proportion of off-feed days, classified based on negative residuals from a 5% quantile regression (QR) of daily feed intake or duration data on age across all pigs (QRFI and QRDUR). Mortality and treatment rate had a heritability of 0.13 (±0.05) and 0.29 (±0.07), respectively. Heritability estimates for RMSEFI, RMSEDUR, QRFI, and QRDUR were 0.21 (±0.07) 0.26 (±0.07), 0.15 (±0.06), and 0.23 (±0.07), respectively. Genetic correlations of RMSE and QR measures with mortality and treatment rate ranged from 0.37 to 0.85, with QR measures having stronger correlations with both. Estimates of genetic correlations of RMSE measures with production traits were typically low, but often favorable (e.g., −0.31 between RMSEFI and finishing ADG). Although disease resilience was our target, fluctuations in FI and duration can be caused by many factors other than disease and should be viewed as overall indicators of general resilience to a variety of stressors. In conclusion, daily variation in FI or duration at the feeder can be used as heritable measures of resilience.
Highlights
Disease resilience can be defined as the ability to maintain relatively undiminished performance levels under infection (Albers et al, 1987; Doeschl-Wilson et al, 2012; Mulder and Rashidi, 2017)
The objectives of this study were to (1) develop and evaluate novel measures of resilience based on daily feed intake and feeding duration data for finishing pigs in a healthchallenged environment and (2) determine heritabilities and genetic correlations of these measures with mortality, treatments, and other economically important production traits
A natural challenge wean-to-finish protocol was established in late 2015 at Centre de développement du porc du Québec (CDPQ) in Québec, Canada, with the aim to mimic a commercial farm with high disease pressure to maximize expression of genetic differences in resilience
Summary
Disease resilience can be defined as the ability to maintain relatively undiminished performance levels under infection (Albers et al, 1987; Doeschl-Wilson et al, 2012; Mulder and Rashidi, 2017). Selecting animals that maintain performance in a typical commercial system provides a natural weighting of resilience to each disease based on the impact of each disease on productivity, along with the incidence or prevalence of the disease. van der Waaij et al (2000) stated that observed production can be viewed as a selection index where the underlying components are weighted based on their impacts on performance It is important, that the testing environment is representative of the target commercial environments. One of the challenges is to obtain heritable measures or indicators of resilience for selection, as elite breeding populations are typically kept in high-health conditions
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