Date Full Report Received01/01/2017
Date Abstract Report Received01/01/2017
InvestigationInstitution: University of Minnesota
Primary Investigator: Yuzhi Li
Co-Investigators: Larry D. Jacobson, Lee J. Johnston, Wayne Martin, Haifeng Zhang
Funded ByNational Pork Board
Background: Tail biting is a common problem in swine production. Tail biting not only causes economic losses for pork producers, but also results in major negative implications for welfare of pigs. Currently, the common method to prevent tail biting is tail docking. While tail docking reduces incidence of tail biting, it does not eliminate the problem completely. Because tail docking is a painful procedure for pigs, it is under scrutiny because of animal welfare concerns. In this project, we quantified the impact of tail docking and tail biting on the welfare and performance of pigs to evaluate the need for tail docking.
Objectives were to: 1. compare incidence of tail biting among pigs with docked tails vs. intact tails; 2. investigate the development of tail biting behavior to predict outbreaks of tail biting; 3. evaluate the impact of tail biting on welfare and performance of victimized pigs and tail biters.
Objective 1: Tail docking reduced incidence and severity of tail damage in both nursery and growing-finishing pigs. During the nursery period, 2% of pigs with docked tails vs. 41% of pigs with intact tails had skin lesions (score 1 or greater) on their tails. None of the docked pigs were scored 2 or greater for their tail lesion, but 7% of undocked pigs were scored 3 or greater, suggesting that undocked pigs suffered from more severe tail damage than docked pigs. During the growing-finishing period, 48% of pigs with docked tails and 89% of pigs with intact tails had skin lesions on their tails at some time point, with 5% of docked pigs and 30% of undocked pigs scoring 3 or greater. Tail docking did not affect weight gain or feed intake of pigs that survived to market. However, compared to pigs with docked tails, pigs with intact tails had higher morbidity. During the growing-finishing period, 5% of docked pigs and 21% of undocked pigs were removed for tail damage or tail biting. As a result, more pigs with docked tails (97% vs. 90%) were harvested without carcass trim loss at the packing plant than pigs with intact tails.
Objective 2: During the growing-finishing period, tail docking reduced tail biting behavior. Pigs with docked tails spent less time tail biting (0.08% vs. 0.33% of observation time; P = 0.01) compared to pigs with intact tails. Outbreaks of tail biting started in pigs with intact tails when they were 11 weeks of age, which was 6 weeks earlier than pigs with docked tails. Pigs with intact tails decreased time spent lying and increased time spent standing/walking 3 days before and during the first outbreak of tail biting, which may be used for prediction of tail biting outbreaks among these pigs. Compared to pigs with docked tails, pigs with intact tails had greater average optical flow, indicating higher activity levels. In addition, optical flow measures of pigs with intact tails changed according to outbreaks of tail biting. Average optical flow of intact pigs was increased during the 1st outbreak of tail biting compared to periods without outbreak. Results of the current study suggest that optical flow analysis might be a promising tool for monitoring activity levels of pigs and predicting outbreaks of tail biting among pigs with intact tails. Results from live observations indicate that tail biting events occurred most at the area near the pen perimeter (37% for docked pigs and 42% for undocked pigs), followed by the feeder area (37% for docked pigs and 26% for undocked pigs), and least at the drinker area (10% for both docked and undocked pigs). Previous studies have shown that tail biting may be alleviated by enriching the environment suggesting that a follow-up study should be conducted placing enrichment devices in locations where tail biting occurs most, such as near pen perimeters and feeders.
Objective 3: Victimized pigs gained less weight between 17 and 21 weeks of age during which tail biting prevailed in this study. More victimized pig carcasses (7% vs. 1%) were trimmed for abscesses or other imperfections at the packing plant, resulting in a lower dressing percentage (74.5% vs. 76.3%; P < 0.05) compared with carcasses from non-victimizedpigs. There was no difference in birth weight, weaning weight, market weight, or overall weight gain during the finishing period among tail biters, victimized pigs and non-victimized pigs. Compared to victimized pigs and non-victimized pigs, tail biters had lower total serum protein (P = 0.01) and Ig-G (P = 0.01) concentrations suggesting that tail biters may suffer from compromised immune functions. For victimized pigs, total serum protein and Ig-G concentrations were elevated 5 days after tail damage suggesting that bitten tails can cause inflammation which in turn may lead to carcass abscesses. No differences in Substance P concentrations were detected among victimized pigs, tail biters, and non-victimized pigs. It is not clear whether tail damage did not cause much pain in the current study or Substance P was not sensitive enough to detect pain in tail-bitten pigs.
Contact details: Yuzhi Li, firstname.lastname@example.org; office: 320-589-1711