Effects of haloperidol, a dopamine D2 receptor antagonist, on feather pecking behaviour in laying hens

https://doi.org/10.1016/j.applanim.2003.11.009Get rights and content

Abstract

Two experiments investigating general behavioural activity and specific pecking behaviour in laying hens under the effect of a dopamine D2 receptor antagonist, haloperidol, were performed. In experiment 1, a total of 240 White Leghorn hens aged 70 weeks were housed in 30 floor pens. Fifty-five of these hens acted as subjects in a dose-response experiment. Behaviour was recorded 30 min before and 30 min after injection of haloperidol or saline. The changes in behaviour were corrected for the effect of saline treatment. The results showed that doses of 0.05, 0.10, 0.20 and 0.50 mg haloperidol/kg body weight (BW) did not give any clear sedative effect, while 1.0 mg haloperidol did so. Thus, the sedative effect seemed to arise at a dose between 0.50 and 1 mg haloperidol/kg and it was concluded that 0.50 mg haloperidol/kg could be used in White Leghorn hens without inducing sedation. In experiment 2, a total of 48 ISA Brown hens aged 118 weeks were used as subjects. The birds were paired with 82-week-old White Leghorn hens chosen at random from an experimental line selected against feather pecking and housed in battery cages. Feather pecking and aggressive pecking were recorded for a period of 50 min before and 50 min after injection of either saline or 0.50 mg haloperidol/kg BW. Feather pecking, but not aggressive pecking, was significantly reduced in the haloperidol treatment (from 1.7 to 0.29 bouts per bird/h, Mann–Whitney U-test N=18, P<0.05; 10.1 to −2.7 pecks per bird/h, P<0.001). The negative value was due to correcting for effect of injection. The results supported our hypothesis that feather pecking behaviour in the adult hen is influenced by dopamine.

Introduction

Feather pecking is a behaviour by which hens destroy the feathers of other hens, in some cases even plucking out feathers and eating these. In some severe cases feather pecking can be followed by cannibalism, where hens eat the blood and tissue of other hens. A wide range of causal factors of feather pecking, such as housing-, rearing-, and feeding factors, have been reported (Sharma et al., 1999) and recently additive (heritable) genetic factors were found to be fundamental (Kjaer and Sørensen, 1997, Kjaer et al., 2001). A majority of authors suggests feather pecking to be a redirection of pecking related to the appetitive phase of feeding behaviour (Blokhuis, 1986, Hoffmeyer, 1969, Wennrich, 1975). Alternatively, mis-imprinting on feathers as a dustbathing substrate followed by redirection of pecking in relation to dustbathing has been suggested that lead to feather pecking and related feather damages (Vestergaard, 1994, Vestergaard and Lisborg, 1993). Stress in relation to lack of coping (Korte et al., 1997, Korte et al., 1999) or stress in more general terms (El-lethey et al., 2001, van Hierden et al., 2001) seem also to affect feather pecking.

The motor patterns of feather pecking are quite similar to those of stereotyped pecking (Bilcik et al., 1999, Blokhuis et al., 1993, Kjaer and Vestergaard, 1999), but no experimental evidence has, hitherto, supported the suggestion of a common physiological background. Self mutilation (plucking and damaging own feathers) in birds is believed to be a variant of stereotyped behaviour (Iglauer and Rasim, 1993). Neuropeptides, particularly endogenous opioids and dopamine, are supposed to play a role in many self mutilating disorders (Cabib, 1993, Goodman et al., 1983), and affected pet birds (e.g. parrots) respond to treatment with various psychoactive drugs (Iglauer and Rasim, 1993, Johnson, 1987, Levine, 1984). Several authors have suggested the influence of the dopamine system in relation to stereotypies in different species of birds. Apomorphine, a D1/D2 receptor agonist, induces stereotypic pecking in pigeons (Cheng and Long, 1974, Goodman et al., 1983), jungle fowl (Kjaer, 2000, unpublished) and domestic fowl (Nictico and Stevenson, 1979). This effect can be reduced by haloperidol, a D2 receptor antagonist (Goodman et al., 1983).

To investigate the potential link between dopamine activity and feather pecking in adult laying hens the objective of the present study was to examine the effects of haloperidol on feather pecking behaviour in adult laying hens. Dopamine antagonists at high doses are known to suppress motor activities in broiler chickens (Kostal and Savory, 1994), but it was not possible to find literature on responses to haloperidol by adult laying hens. Therefore, the study comprised two experiments. First, the general behavioural time budget was recorded in a dose-response experiment in order to find the maximal dose without major sedative effects. Then, in a second experiment we tested the effect of this dose of haloperidol on pecking behaviour. Our working hypothesis was that feather pecking in adult hens would be reduced by haloperidol.

Section snippets

Animals and housing

A total of 240 White Leghorn laying hens from a random-bred control line kept at the institute for several decades (Kjaer et al., 2001) were used. The birds were at 70 weeks of age moved from four-bird battery cages (Big Dutchman) to floor pens, comprising 30 groups of eight birds each. Groups were compounded with respect to previous location on tiers (Jones, 1985) and mixed one bird from eight different cages to ensure equal unfamiliarity between group members. To facilitate individual

Subjects and housing

A total of 48 ISA Brown hens were used as subjects. The birds were 118 weeks old and housed in a two tier cage battery system (same as used in experiment 1) in groups of four hens prior to the experiment. Three days before the behavioural observations each experimental hen was paired with a White Leghorn hen, acting as pen mate and feather pecking recipient and placed in the same type of four-bird battery cage, one pair per cage. The 82-week-old White Leghorn hens were chosen at random from an

Discussion

We have shown that haloperidol selectively reduces the level of feather pecking in laying hens. The selective effect of a dopaminergic drug on feather pecking gives good support to the hypothesis that feather pecking may be related to stress and can be regarded as a stereotypy under control of the dopamine system. Contrary, aggressive behaviour seems not to be under dopaminergic control. This distinction between aggression and feather pecking is in accordance with the behaviour-genetic approach

Acknowledgements

The Danish Ministry of Food, Agriculture and Fisheries financially supported these experiments. The authors wish to thank Jens Malmkvist for valuable comments on earlier versions of this manuscript as well as Kirsten L. Balthzersen and Inger Marie Jepsen for excellent technical support.

References (27)

  • Blokhuis, H.J., Beuving, G., Rommers, J.M., 1993. Individual variation of stereotyped pecking in laying hens. In:...
  • Cabib, S., 1993. Neurobiological basis of stereotypies. In: Lawrence, A.B., Rushen, J. (Eds.), Stereotypic Animal...
  • I. Hoffmeyer

    Feather pecking in pheasants—an ethological approach to the problem

    Dan. Rev. Game Biol.

    (1969)
  • Cited by (49)

    • Where in the serotonergic system does it go wrong? Unravelling the route by which the serotonergic system affects feather pecking in chickens

      2018, Neuroscience and Biobehavioral Reviews
      Citation Excerpt :

      Thus, D1 and D2 receptors play a role in aggression, likely via their influence on 5-HT levels in the RN. Interestingly, D2 receptor activity is also involved in FP, namely in adult HFP hens, a D2 antagonist (Haloperidol) decreased FP, foraging, walking and eating, but not aggression (Kjaer et al., 2004). These results are likely caused by Haloperidol blocking the effects of DA and increasing frontal and NAc’ DA (Bonaccorso et al., 2002; Li et al., 2005) and increase in overall behavior inhibition (Logemann et al., 2017).

    • Abnormal repetitive behaviours in captive birds: a Tinbergian review

      2018, Applied Animal Behaviour Science
      Citation Excerpt :

      Generally, ARBs are reduced through activation of the indirect or suppression of the direct pathway, demonstrated experimentally by administration of dopaminergic and serotonergic drugs (Langen et al., 2011). For instance, apomorphine, a D1 and D2 receptor agonist (van Hierden et al., 2005) induced object-pecking in male Japanese quail, Coturnix japonica (Castagna et al., 1997), and male laying chicks (Machlis, 1980), while Kjaer et al. (2004) reduced FP in laying hens with haloperidol, a D2 receptor antagonist. Similarly, a 5-HT1A receptor agonist that reduces 5-HT synthesis increased severe FP in high FP line laying chicks (also see Section 2.2.1.2: van Hierden et al., 2004a), whereas dietary supplementation of a 5-HT precursor, tryptophan, stimulated serotonergic neurotransmission and reduced FP in young laying chickens (Savory, 1998; Savory et al., 1999; van Hierden et al., 2004b).

    • Quantitative genetic analysis of causal relationships among feather pecking, feather eating, and general locomotor activity in laying hens using structural equation models

      2016, Poultry Science
      Citation Excerpt :

      Van Hierden et al. (2005) reported differences in apomorphine sensitivity between high and low FP lines of laying hens. Furthermore, it has been shown that dopamine D1/D2 receptor agonists influence stereotypic pecking in pigeons (Goodman et al., 1983) and domestic fowl (Nistico and Stephenson, 1979) and FP in laying hens (Kjaer et al., 2004). Linear mixed models have been used to quantify the relationship between FP and FE (Bennewitz et al., 2014) or between FP and activity (Rodenburg et al., 2004).

    View all citing articles on Scopus
    View full text