Understanding tail biters and victimized pigs during outbreaks of tail biting

Abstract Text:

Tail biting is a common problem in growing-finishing pigs, which can compromise health, growth and welfare of pigs. Since tail biting is an abnormal behavior performed by tail biters towards victimized pigs, understanding these pigs may help us solve the problem. This study was conducted to evaluate immune function of tail biters and victimized pigs. Pigs (n = 240, initial wt = 25.7 ± 2.9 kg) were housed in 8 pens of 30 pigs for 16 wk. Once visible blood on a tail appeared, pigs in that pen were assessed daily for tail score (0 = no damage; 1 = healed lesions; 2 = visible blood without swelling; 3 = swelling and signs of infection; 4 = partial or total loss of the tail). Victimized pigs were defined as pigs with tail scores equal to or greater than 2. Meanwhile, a 2-h observation was conducted for two consecutive d to identify tail biters. In each pen that tail biting occurred, blood samples were collected from victimized pigs on the day that tail biting was first observed, as well as from tail biters and 2 control pigs with no sign of tail damage. Fourteen biters (6 barrows; 8 gilts), 30 victimized pigs (21 barrows; 9 gilts), and 28 control pigs (14 barrows; 14 gilts) were identified for blood sampling. Total serum protein and Ig-G concentrations were analyzed using the spectrophotometric method. Data were analyzed using the Glimmix model of SAS. Compared with control and victimized pigs, tail biters had lower total serum protein (P = 0.01; Table 1) and Ig-G concentrations (P= 0.01), suggesting poor immunity. There were no differences in total serum protein or Ig-G concentrations between control and victimized pigs. These preliminary results suggest that tail biters may experience compromised immunity.

Table 1. Total serum protein, Ig-G, and tail scores of control pigs, victimized pigs, and tail biters
Item	Control	Victims	Biters	P <
n	28	30	14
Total serum protein, g/L	66.1 ± 1.1a	64.5 ± 1.1a	60.3 ± 1.5b	0.01
Ig-G, g/L	14.0 ± 0.6a	13.1 ± 0.6a	10.6 ± 0.9b	0.01
Tail score	0.1 ± 0.1b	2.5 ± 0.1a	0.2 ± 0.1b	< 0.001

^abMeans within a row without a common superscript differ (P< 0.05).

Keywords: Immunity, pigs, tail biting