Newer varieties of fava beans have a lower tannin content than previous varieties, which makes them an interesting option as animal feed. A study at Aarhus University in Denmark therefore set out to evaluate the value of feeding fava beans to piglets.
The fava bean, a grain legume and a species of vetch, is used in both animal feed as well as for human consumption. It is nutritious, rich in fibre, can be grown in winter and spring, and is nitrogen-fixing. An interesting advantage of this species is that it has the potential to be grown more widely in northern Europe.
The variegated (tannic) varieties were first tested on piglets. The experiment was designed with 1 control group that was given soy-based compound feed, and 3 experimental groups which each received pelleted dry feed with 25% fava beans. One experimental group received the white-flowered black Columbo (tannin-free) variety and the other 2 the Fuego and Espresso tannin-containing varieties, respectively.
The experiment showed no difference in feed intake across the groups. However, for the entire weaner period (9-30 kg), the results from the 3 experimental groups were just as good or even exceeded results in the control group of piglets.
The 2 groups that received 25% variegated fava bean diet (Fuego or Espresso), had statistically higher daily growth than both the control group and the group of piglets that received 25% white-flowered fava bean diet (Columbo).
The health of the pigs was generally good, and mortality was low across all the groups. Interestingly, however, was that the number of days when pigs became treated for diarrhoea was significantly lower for the Espresso group compared to the Columbo. There was a trend for fewer treatment days for the Fuego group (P = 0.07) compared with the control group.
It has previously been recommended that only white-flowered (tannin-free) fava beans be used as a feed ingredient for pigs, but the results from this test showed that the Fuego and Espresso varieties with coloured flowers (tannin-containing) could advantageously be used in mixtures for piglets from 9-30 kg.
In another experiment, the Fuego variety of fava beans was included at 21% of wet feed for fattening pigs. The pigs had no problem with the taste of the feed and no challenges were noted with feed intake of the fava bean mixture. The pigs performed well with only a marginally lower feed utilization (0.02) per kg gain and a lower production value of 4%.
This experiment confirms the results from the piglet experiment, that white-flowered varieties and the varieties Fuego and Espresso fava beans can be used in up to 20% of pig feed rations.