Patterns of mortality in the finishing stage on 3 experimental pig farms

Introduction: Mortality and its evolution in pig finishing has received little attention compared to pre- and postweaning mortality. Pigs dying at an older age and weight represent, however, a higher investment and value compared to early mortalities. As such, knowledge about pig mortality chances at different ages may influence management decisions. To get an idea of 1) the pattern of mortality in function of bodyweight, 2) the variability of mortality over years, and 3) the differences between farms, we compared mortality records for three experimental farms over 4 years. Materials and Methods: The farms differed in stocking strategy: farm A sold the majority of its piglet production and finished the remaining piglets while farms B and C bought its piglets from a supplier. Cumulative mortality curves in function of bodyweight were constructed per year per farm. For all farms, third degree polynomials were fitted to the cumulative mortality curves. Results: The form of the functions differed between farms A: y = 8E-05x3 - 0.0262x2 + 3.2759x - 52.724; farm B: y = -0.0002x3 + 0.0461x2 - 1.8957x + 26.208 ; farm C: y = -6E-05x3 + 0.0175x2 - 0.5312x + 10.032 with y the cumulative mortality and x bodyweight (kg).Mortality between 20kg and slaughter amounted to 4.55% (2.64 – 6.01% per year) for farm A, 1.05% (0.64 – 1.94%) for farm B, and 1.11% (0.60 – 1.92%) for farm C.On farm A, 25% of the piglets died before 30kg, 50% before 46kg and 75% before 69kg. On farm B, this was 53kg, 70kg and 85kg and on farm C, 56kg, 81kg, and 103kg. While the form of the function was relatively constant over the years in farm A, this was less for farm B or C. A reason may be the difference in total absolute mortality. Less mortalities on farm B and C, increase the influence of one mortality on the function’s form. The difference in total mortality between these farms is large. We hypothesize that stocking strategy may play a role. When selling piglets, it is important to have uniform and healthy groups of piglets. Therefore, aberrant piglets may not be sold and might have a higher risk of dying. This might coincide with the higher percentage of dead pigs at a lighter bodyweight. In contrast, a finishing farm may benefit from selecting healthy piglets, diminishing the risk that pigs die during finishing. This hypothesis needs testing on a larger set of farms. Conclusion: Based on the observed mortality figures in these farms, we conclude that the pattern of mortality in function of bodyweight is subject to differences between farms and years. However further research needs to investigate the use of such mortality curves in management support systems.

Publication year:2016