Importance of Providing Roughage to Organic Growing/Finishing Pigs

Pigs are naturally curious and keen to explore their environment. Exploring, foraging and rooting behaviours are a large part of pigs' general activities and are performed to search for possible locations of food and to gather general information on their surroundings. The requirements for increased space allowances and outdoor runs for organically raised pigs allow them more possibilities to be active and express their natural behaviours. Roughage is an important element in organic production systems as it can influence the pigs' activity pattern and social interactions by increasing their motivation to explore and forage (Roberts et al., 1993). By increasing the time spent foraging or rooting; roughage can keep pigs occupied and potentially reduce stress and aggression between individuals.

Roughages can also make a significant contribution to the pigs' diet. Although they are monogastrics, pigs have a capacity to digest forage fibres in the hindgut. Research has shown that roughage can be included in the total diet up to 18-19% of dry matter and that pigs over 60 kg, are able to consume 10% of their daily energy requirement from roughage (Carlsson et al., 1999). Roughages may also be a way to improve the well-being of pigs because they positively affect the development of the micro flora and epithelium in the gut.

In a recent study, Høøk-Presto et. al. (2009) examined the effects of roughage on organic growing/finishing pigs' activity behaviour and social interactions. Their proposal was that access to additional roughage in the outdoor area would make the pigs use this area more frequently, change their activity pattern and reduce aggressive behaviour and stress among the pigs. In the first part of their experiment a total of 377 organic pigs of mixed gender from 3 different herds were used. All pigs were of (Landrace x Yorkshire) x Hampshire breed and were purchased from two organic piglet-producing herds. The pigs were randomly allocated according to sex and live weight to either a control treatment (C) or one of three treatments with access to additional roughages; hay (H), grass silage (GS) or whole crop barley silage (BS).

The experiment was carried out during November-February when the pigs were housed indoors with access to an outdoor run. The average outdoor temperature during this time was 0.7 °C (min. ?10.0°C and max. 10.5 °C). Each barn was divided into pens which contained a bedded lying area, unlimited access to water and feeding troughs which allowed all pigs to eat simultaneously. The total indoor area provided was 1.5 m2/pig. Each pen also allowed access to a concrete outdoor run that provided at least 1.0 m2/pig. Pens that were allocated to roughage treatments (i.e. hay, grass silage or whole crop barley silage) were given their respective roughages ad libitum in feeding hedges in the outdoor area. Roughage was replenished every morning and if needed in the afternoon. Behaviour observations were performed in all pens at arrival and later every four weeks throughout the growing/finishing period.

The researchers found that pigs that had access to roughage in feeding hedges stayed outdoors more frequently than pigs without roughage (Figure 1). Pigs that were provided hay, grass silage or whole crop barley silage stayed outdoors on average 9.6%, 12.5% and 10.9%, respectively, compared to 3.8% for pigs in the control group. Exploring behaviour (defined as rooting in straw or other and eating roughage) did not differ between treatments which may have been due to the availability of bedding in all pens. Interestingly, the percent of observed pigs that were eating roughage did not differ significantly between the hay, grass silage and whole crop barley silage treatments.

When analysing the behaviour variable being active (defined as standing and eating roughage), pigs in roughage treatments were significantly more active than control pigs (Figure 1). Control pigs were significantly less active (standing and eating roughage) outdoors than pigs with additional roughage, which indicates that the roughage encouraged pigs to go outdoors and to be more active.

Figure 1: Effect of Roughage on Pig Activity and Level

Indoors, the frequency of aggressive behaviour in the lying area was lower for pigs with access to roughage than for pigs in the control treatment. Outdoors, the frequency of aggressive behaviour did not differ; however, the frequency of aggressive behaviour outdoors was in general low.

The results from this study show that access to additional roughage outdoors reduced the frequency of aggressive behaviour in the lying area. They also confirm that access to additional roughage in the outdoor run encourages pigs to go outdoors more frequently and suggests that pigs might be more motivated to use the roughage to explore and forage. Although straw bedding was provided indoors, access to additional roughage outdoors increased the activity level of the pigs and reduced aggressive behaviour. This indicates that roughage is an important resource that can influence the well-being and the behaviour of pigs especially in organic production systems.

Sources:

Roberts, S., Matte, J.J., Framer, C., Girard, D.L., and Martineau, G.P. 1993. High-fibre diets for sows: effects on stereotypies and adjunctive drinking. Appl. Anim. Behav. Sci. 37: 297-309.

Carlsson, D., Lærke, H.N., Poulsen, H.D., and Jørgensen, H., 1999. Roughages for growing pigs, with emphasis on chemical composition, ingestion and faecal digestibility. Acta Agric. Scand., Sect. A, Animal Sci. 49: 129-136.

Høøk Presto, M., Algers, B., Persson, E., and Andersson, H.K. 2009. Different roughages to organic growing/finishing pigs - Influence on activity behaviour and social interactions. Livestock Science. 123: 55-62