Tail Biting in the Nursery: Evaluating Postural, Spatial, and Behavioral Differences Between Tail Biter and Victim Pigs

Authors

• Storey L. Forster, University of Nebraska-LincolnFollow

First Advisor

Ty B. Schmidt

Committee Members

Benny Mote, Gary Sullivan

Date of this Version

5-2026

Document Type

Thesis

Citation

A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science

Major: Animal Science

Under the supervision of Professor Ty Schmidt

Lincoln, Nebraska, May 2026

Comments

Copyright 2026, Storey L. Forster. Used by permission

Abstract

This study examined behavioral differences among pigs classified as tail biters, victims, or neutral during the nursery period. A total of 192 undocked nursery pigs were assigned to eight pens and monitored for 30 days using the NUtrack system. Tail biting events were identified from video observations, and pigs contributing to the top 25% of observed tail biting activity were classified as tail biters. Based on weekly tail scoring, pigs assigned a maximum tail injury score ≥ 2 were classified as victims. All other pigs were considered neutral. A total of 700 tail biting events were observed. Thirty-eight pigs were classified as tail biters, 54 pigs were classified as victims, and 100 pigs were classified as neutral. During observed tail biting events, tail biters were most frequently standing (73%; P < 0.001), while recipient pigs were most often lying sternal (70.0%; P < 0.001). Tail biting interactions occurred most frequently in the middle one-third of the pen (53.6%; P < 0.001). Meters walked/day (classification x day; P = 0.02) and time spent lying lateral (classification x day; P < 0.01) differed among classifications on select days. Other behaviors, including revolutions/day, time spent standing, at the feeder, sitting, and lying sternal, varied across the nursery but did not differ among classifications (P < 0.001; day effect). Changes in revolutions (P ≤ 0.001), meters walked (P ≤ 0.03), and standing (P ≤ 0.01) were elevated from the MTIS-3⁺ event day on multiple days up to 14 days before injury detection in pigs observed with severe tail injury. Changes in sitting and total resting behaviors were reduced compared to the MTIS-3⁺ event day during the same period (P ≤ 0.04). These results indicate that tail biting is associated with specific posture during tail biting and that increases in activity and reductions in resting behavior may precede the onset of severe tail damage. These findings suggest that increases in activity and reductions in resting behavior precede the onset of tail biting and could serve as early indicators that may not be detected through traditional human observation.

Advisor: Ty B. Schmidt