Risk factors for vulva biting in breeding sows in south‐west England

Review: Early life predisposing factors for biting in pigs

The pig industry faces many animal welfare issues. Among these, biting behaviour has a high incidence. It is indicative of an existing problem in biters and is a source of physical damage and psychological stress for the victims. We categorize this behaviour into aggressive and non-aggressive biting, the latter often being directed towards the tail. This review focusses specifically on predisposing factors in early life, comprising the prenatal and postnatal periods up to weaning, for the expression of aggressive and non-aggressive biting later in life. The influence of personality and coping style has been examined in a few studies. It varies according to these studies and, thus, further evaluation is needed. Regarding the effect of environmental factors, the number of scientific papers is low (less than five papers for most factors). No clear influence of prenatal factors has been identified to date. Aggressive biting is reduced by undernutrition, cross-fostering and socialization before weaning. Non-aggressive biting is increased by undernutrition, social stress due to competition and cross-fostering. These latter three factors are highly dependent on litter size at birth. The use of familiar odours may contribute to reducing biting when pigs are moved from one environment to another by alleviating the level of stress associated with novelty. Even though the current environment in which pigs are expressing biting behaviours is of major importance, the pre-weaning environment should be optimized to reduce the likelihood of this problem.

Preliminary evaluation of a prototype welfare monitoring system for sows and piglets (Welfare Quality® project)

The Welfare Quality® project aims to develop a European on-farm welfare assessment standard for pigs, amongst other species. A prototype monitoring system was developed for sows and piglets using predominantly animal-based measures of behaviour, health and physiology to assess welfare. The prototype monitoring system was evaluated on a total of 82 farms in the UK and The Netherlands, encompassing a wide variety of farming systems. Preliminary analysis of the data indicates that the incidence of clinical welfare problems were low, with 1.2, 0.8, 1.1 and 0.1%, respectively of pregnant and lactating sows recorded as having substantial skin lesions, bursitis and vulval lesions, and extremely poor body condition. Some clinical problems were more prevalent in certain types of feeding system than others, particularly the severity of vulval lesions with electronic sow feeding (ESF) systems. Fear of humans, assessed by the extent of withdrawal behaviour from an unknown human, was low, and median scores were similar for sows housed in groups indoors, outdoors and in stalls. Some form of stereotyped behaviour was observed on almost 75% of farms visited, with sham chewing the most commonly recorded stereotyped behaviour. System design affected the practicality of some measures, particularly on outdoor farms. Full investigation of the complete data set will enable a refined, final, on-farm monitoring system to be developed and benchmark standards established.

A Descriptive Survey of the Range of Injuries Sustained and Farmers’ Attitudes to Vulva Biting in Breeding Sows in South-West England

The within-farm prevalence of vulva biting in breeding sows in south-west England was investigated using a postal survey sent to 410 pig farmers in January 1997. The response rate was 65 per cent and there were 83 useable replies. The majority of farms where vulva biting was reported indicated a low within-farm prevalence of 1-9 per cent of sows affected, although prevalences as high as 30-60 per cent were reported. The injuries reported ranged from bleeding to removal of the whole vulva, the most commonly reported injuries being bleeding and superficial damage to the vulva. No long-term effects from this injury to service and dry sows were reported by 70 per cent and 76 per cent of farmers respectively. Competition for food, aggressive sows, closeness to farrowing and mixing of sows were the most common reasons suggested by these farmers as causes of vulva biting.