Ethological investigations on the perpetrators and victims of tail biting in weaner pigs

Are biters sick? Health status of tail biters in comparison to control pigs

BACKGROUND

Tail biting is a multifactorial problem. As the health status is one of the factors commonly linked to tail biting, this study focuses on the health of identified biters. 30 (obsessive) biters are compared to 30 control animals by clinical and pathological examination as well as blood and cerebrospinal fluid samples. In that way, altogether 174 variables are compared between the groups. Moreover, connections between the variables are analysed.

RESULTS

In the clinical examination, 6 biters, but only 2 controls (P = 0.019) were noticeably agitated in the evaluation of general behaviour, while 8 controls were noticeably calmer (2 biters, P = 0.02). Biters had a lower body weight (P = 0.0007) and 13 biters had overlong bristles (4 controls, P = 0.008). In the pathological examination, 5 biters, but none of the controls had a hyperceratosis or inflammation of the pars proventricularis of the stomach (P = 0.018). However, 7 controls and only 3 biters were affected by gut inflammation (P = 0.03). In the blood sample, protein and albumin levels were below normal range for biters (protein: 51.6 g/l, albumin: 25.4 g/l), but not for controls (protein: 53.7 g/l, albumin: 27.4 g/l), (protein: P = 0.05, albumin: P = 0.02). Moreover, 14 biters, but only 8 controls had poikilocytosis (P = 0.05). Although not statistically different between groups, many animals (36/60) were affected by hypoproteinemia and hyponatremia as well as by hypokalemia (53/60) and almost all animals (58/60) had hypomagnesemia. For hypomagnesemia, significant connections with variables linked to tail damage and ear necrosis were detected (rs/V/ρ ≥ 0.4, P ≤ 0.05).

CONCLUSION

The results suggest that behavioural tests might be helpful in identifying biters. Moreover, cornification and inflammation of the pars proventricularis is linked to becoming a biter. Furthermore, the results highlight the need for appropriate and adjusted nutrient and mineral supply, especially with regard to magnesium.

The gut microbiota and microbial metabolites are associated with tail biting in pigs

Tail biting is an abnormal behaviour that causes stress, injury and pain. Given the critical role of the gut-microbiota in the development of behavioural problems in humans and animals, the aim of this study was to determine whether pigs that are biters, victims of tail biting or controls (nine matched sets of pigs) have a different microbiota composition, diversity and microbial metabolite profile. We collected faecal and blood samples from each individual for analysis. The gut microbiota composition was most different between the biter and the control pigs, with a higher relative abundance of Firmicutes in tail biter pigs than the controls. Furthermore, we detected differences in faecal and plasma short chain fatty acids (SCFA) profiles between the biter and victim pigs, suggesting physiological differences even though they are kept in the same pen. Thus, in addition to supporting an association between the gut microbiota and tail biting in pigs, this study also provides the first evidence of an association between tail biting and SCFA. Therefore, further research is needed to confirm these associations, to determine causality and to study how the SCFA profiles of an individual play a role in the development of tail biting behaviour.

Is There a Link between Suckling and Manipulation Behavior during Rearing in Pigs?

Simple Summary

Tail biting, a well-known problem in modern pig production, reduces pigs’ welfare and causes economic losses. It is influenced by several external and internal factors, such as housing condition, management, genetics, and age of the animals. Within the internal factors, the individual predisposition to tail biting is difficult to identify. In our study, we analyzed the manipulation behaviors of weaner pigs and their relationship with agonistic behaviors of the piglets during suckling to identify groups of piglets which showed similar suckling and rearing behaviors. In our experiment tail biting increased at the middle and end of rearing. Most animals were observed as both biters and victims of tail biting. During our observations, we found indications that tail-biting pigs showed mainly submissive behavior in teat disputes. These pigs might compensate their submissiveness by biting tails to chase other pigs from resources with restricted access, such as feed or enrichment material. Further research should consider more aspects of a pigs’ personality suitable for early identification of pigs predisposed for later tail biting. This early identification would allow intervention measures to be taken earlier, thereby reducing tail biting and its consequences.

Abstract

Inadequate possibilities to perform oral manipulation behavior for pigs can lead to misdirection and thus tail biting. Our study aimed to analyze manipulation behaviors of weaner pigs with focus on tail biting and the relationship with agonistic characteristics of the piglets during suckling. We analyzed the individual manipulation behavior of 188 weaner pigs. General health condition and tail lesions were determined weekly. Correlations were estimated between weight at weaning and at the end of rearing period, frequency of manipulative rearing behaviors and Dominance and social tension index based on suckling behavior. Principal component and cluster analyses were performed to identify groups of piglets which showed similar suckling and rearing behaviors. Tail biting increased at the middle and end of rearing with switching roles of biters and victims. Tail lesions were correlated with received tail biting behavior but occurred with a delay of more than a week. The frequency of performed tail biting was correlated with dominance index (r_s = −0.256, p < 0.01) and weaning weight (r_s = −0.199, p < 0.05). We assume that performed tail biting is more often observed in pigs who show mainly submissive behavior in teat disputes.