Cost benefit analysis of health management strategies in finishing pigs
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Research partners: Newcastle University and Thirsk VLA
Sponsor: BPEX
Duration: 2007 - 2010
This PhD research explored the use of different preventative disease management strategies for pigs and their ability to improve detection and limit the spread of disease, thus improving the overall health and productivity of finishing pigs. The focus was to evaluate effective strategies that would aid in improving the monitoring and control of endemic disease within the finishing herd, yet could be employed by producers immediately, at little or no extra cost.
The study began by comparing the use of all-in all-out (AIAO) and continuous flow (CF) systems for finishing pigs with or without a disinfection routine (see annual report 2008-2009). Analysis of blood samples from this trial indicated an elevation in Acute Phase Proteins (APPs), generalised markers of activation of the pig’s immune system, in less hygienic environments. These APPs might provide a useful index of the level of subclinical challenge compromising performance. A second study, in collaboration with the Veterinary Laboratories Agency, Thirsk, examined the efficiency of using cotton rope to collect pooled oral fluid (comprising mainly of saliva) samples from groups of pigs, allowing whole pens to be screened for diagnostic purposes from just one sample (see annual report 2009-2010).
The third study explored the possibility of utilising a pooled oral fluid sample for detection of sub-clinical disease in groups of pigs by monitoring the levels of APPs. To validate the methodology, paired blood and oral fluid samples were taken from a cohort of finishing pigs housed in a building where sub-clinical disease was thought to be contributing to sub-optimal growth rate. Blood and oral fluid samples taken from the same pigs were analysed for two APPs, Haptoglobin (Hp: a protein that increases in concentration in response to a wide variety of acute and chronic immune activation) and C-reactive protein (CRP: a protein that increases in concentration under acute inflammatory conditions). The paired samples were also analysed for antibodies and viremia levels of Porcine Reproductive and Respiratory Syndrome virus (PRRSv), an economically significant disease known to be present at the study farm. This analysis was conducted by the VLA, which has been trialling the techniques to achieve accurate detection of the European strain of the PRRSv in oral fluid.
Results showed that growth rate of the pigs was sub-optimal at 0.65 kg per day, although there were few clinical signs of disease during the study. The concentration of APPs in blood serum correlated to the levels in oral fluid, indicating that the use of oral fluid for APP testing is a feasible, non-invasive method.
Investigation of predictive factors that were related to the concentrations of APPs in individual pigs revealed that the duration of time the pigs had been housed in the continuous-flow finisher building was related to the concentrations of the APPs, demonstrating that pigs were experiencing infectious challenge upon entering the building.
Average daily gain of animals in the finisher period and also the lifetime growth performance of the pigs were related to the concentration of Hp detected, providing evidence that the pigs were experiencing growth depression as a result of immune activation at this time. Testing oral fluid collected in a pooled sample from each pen, the concentration of CRP was positively correlated to the average daily gain of the pen. This provides initial evidence that it may be possible and cost effective to monitor the level of immune activation linked to performance loss of a large group of individuals using APPs tested for in pooled oral fluid samples.
The final study investigated the use of water consumption data to monitor pig performance and provide an early warning of upcoming disease outbreaks. The number of pig businesses in the UK that have automated water consumption recording is growing and there is scope to gain extra value from these data. Data from real-time monitoring of water intake of 24 pens of finisher pigs raised on a farm with chronic respiratory disease pressure is being used to investigate whether there is any link between deviations in daily water intake patterns that could indicate changes in health and growth rate. In the long run, utilising this recording system could provide a reliable automated early warning system of health or management problems, in addition to flagging up water wastage issues.
To determine predictors in the daily variation in water consumption by a pen of growing pigs a preliminary model including the number of pigs in the pen, weight of the pigs, drinker type and environmental temperature found these factors to account for 42% of the total variation in the daily water consumption. The next analysis stage is to clarify whether episodes of disease symptoms can be used to further explain variation in water intake.
Implications
Finisher pigs are the end product of on-farm production and where most money should be made. Underperformance in this area will result in major losses and therefore problem areas need to be picked up quickly so action can be taken. However, action is only possible with consistent, regular and effective observation, and greater emphasis needs to be placed on this.
This research has shown where clinical symptoms are evident, substantial losses to production from decreased growth and increased FCR have already occurred. Improving awareness of where sub-clinical symptoms are occurring can allow prompt action to be taken in treating pigs where necessary. With the technologies being developed in this research, targeting disease at the sub-clinical stage is becoming a reality and one that could be low cost in terms of diagnostics.
Figure 1: Percentage of a pen group of pigs having chewed one or two lengths of rope provided for up to 60 minutes.
Page last updated
11 April 2011