Feed barrier design affects behaviour and physiology in goats

Abstract

Among other things, feed barrier design for goats can differ with regard to ease of leaving, backward view, and presence of physical separation. The aim of our study was to investigate whether the type of feed barrier influences agonistic behaviour and stress. The study involved 55 adult non-lactating female goats of several Swiss dairy breeds. Three groups of 14 and one group of 13 goats (2 horned, 2 hornless) were rotated between four pens with different types of feed barriers (neck rail, metal palisade, wooden palisade, diagonal fence). Each group stayed four weeks with each feed barrier type. Social interactions in the feeding area were recorded for 12 h per group and feed barrier type (1.5 h on 8 days each group) and corrected by the average number of feeding animals. Heart rate and heart rate variability were measured in lying and undisturbed goats to evaluate chronic stress independently of actual levels of motor activity and agonistic interactions. Individual faecal samples were taken for analysis of the concentration of cortisol metabolites. Data were analysed by linear mixed-effect models taking into account interactions between the type of feed barrier and presence of horns. Hornless goats displayed the most agonistic behaviour with physical contact in the feeding area of the neck rail and diagonal fence and least in the feeding area of the metal palisade, whereas goats with horns showed much fewer interactions of this behaviour; thus, only slight differences depending on the type of feed barrier were found ( p < 0.0001). Hornless goats also displayed the most agonistic behaviour leading to displacements from the feeding place with the neck rail, whereas for horned goats the effect of the type of feed barrier was less distinctive ( p = 0.0009). The duration of leaving the feed barrier was longest with the diagonal fence for both horned and hornless goats, while the horned goats also took longer to leave the neck rail compared to the palisades ( p = 0.0194). The interaction of type of feed barrier and presence of horns showed an effect on heart rate variability in the parameters root mean square of successive interbeat interval differences (RMSSD; p = 0.0355), RMSSD in relation to the standard deviation of all interbeat intervals (RMSSD/SDNN; p = 0.0215) and determinism ( p = 0.0364). The metal palisade distinctly differed from the diagonal fence as well as from the neck rail in hornless goats, with highest heart rate variability (HRV) and thus lowest levels of chronic stress in the pen with the metal palisade. Independently of horn status, the concentration of faecal cortisol metabolites tended to be lowest for goats in the pen with the metal palisade ( p = 0.0600). In summary, the metal palisade showed the most beneficial effects, especially on hornless goats. In contrast to the neck rail and the diagonal fence, both types of palisades seem to be recommendable for feeding goats in loose housing.