Motivation for eating roughage in sows : as an indiction of hunger

Abstract: Today’s feeding methods can determine the domestic pig’s abilities to fulfill basic behavioral needs, such as foraging, and the way in which pigs are feed is an important aspect. Feed does not only provide the energy and nutrients critical for survival, but feeding is also associated with a number of other factors contributing to well-being and reproduction. Today the feed for gestated sows is often composed by high energy and low dietary fiber grain products such as wheat. Three kg of this kind of feed can often be consumed by the sow within 20 minutes. Hunger leads to stress which often causes some kind of stereotypic behavior. One way to reduce that kind of behavior and to relieve the feeling of hunger and stress is to allow the sow access to low energy, high fiber feedstuff in the form of roughage. At least half of the sows requirements for energy intake can be covered by roughage without affecting the production and access to roughage gives the sows a possibility to perform a feeding behavior they are highly motivated to perform. The performance of stereotypies has been used as evidence of reduced welfare; when an animal has a high motivation to perform a certain behavior but the environment does not allow the animal to perform this. So how can high motivation to perform a certain feeding related behavior due to hunger, be measured? The aim of this study was to investigate if sows given a lower amount of concentrate feed are more motivated to eat silage. In the study a total of 39 gestated Yorkshire and Yorkshire x Swedish Landrace sows were given either a restricted amount of commercial feed, 60 percentages, or 100 percentage of recommended feed ratio together with free amount of grass-silage. The results showed that the sows with lower commercial feed ratio had a 17 percentage higher frequency of time spend chewing on silage and they also had a 52 percentage lower average duration time from opening the feeding crate after feeding, until chewing on silage for the first time. The results can correspond to that sows given a lower feed ratio have a higher motivation for eating silage due to hunger. During the treatment period weight and backfat thickness gain differed between treatments and was lower among sows given 60 percentage commercial feed ratio. However this did not have any effect on piglet production.