Pig Nutrition: Forage Feeding with Alternative Protein

There is an urgent need to develop commercially viable feeding systems using organic rations that will meet the nutritional requirements of pigs and support animal health and welfare.
calendar icon 31 July 2015
clock icon 6 minute read
sustainable pig production,forage, the pig site
Figure 1. Gloucester Old Spot pig feeding on a forage-based ration at FAI

The Food Animal Initiative (FAI) and the Organic Research Centre (ORC) are addressing current challenges in UK pig production through practical research that explores alternative, sustainable feeding systems utilising silage and locally grown sources of protein.

The challenges

With wide-scale intensification of pig production and legislative exclusion of waste food in pig diets, the price of grain-based feeds including soybean meal are rising alongside demand.

Feed accounts for up to 65% of the cost of conventional pig production in England (BPEX 2012), placing significant economic pressures on the industry. Increasing global consumption of livestock products has driven the rise in soybean production by more than 400% in the past 40 years, more than any other commodity crop. As a result, large areas of rainforest and other vital biomes are undergoing conversion to agricultural land for soybean culture and ranching, with substantial and extensive environmental and ecological impacts.

In the organic sector, EU regulations require pig producers to feed a 100% organic diet from 2015. As a result, there is an urgent need to develop commercially viable feeding systems using organic rations that will meet the nutritional requirements of pigs (see Figure 1) and support animal health and welfare. In addition, EU legislation requires pigs in all systems to have access to manipulable materials to satisfy their behavioural need to forage, and to displace abnormal aggressive behaviours such as tail biting.

Forage for pigs

Pigs are naturally omnivorous foragers, and their dietary needs are outlined in Table 1. Although pigs are usually offered cereal-based rations, the hindgut can digest cellulosic, fibrous feed and accounts for 48% of the pig’s fermentative capacity (Van Soest 1994).

This enables them to digest a variety of other foodstuffs including plant materials such as grass. Herbage can make a valuable contribution to nutrition at all stages of pig development, offering a source of minerals and vitamins, enhancing feed intake and supporting gut health by reducing the risk of gastric ulceration associated with grain-based feeds.

In addition, the provision of herbage-based diets facilitates foraging behaviours that engage pigs in natural activity for 70% of their time, and as such can displace abnormal aggressive behaviours such as tail biting.

FAI has been feeding home grown silage-based rations to its small indoor pig herd for over 10 years, and has most recently investigated the use of forage legumes such as lucerne silage to improve the contribution of forage to protein provision.

Table 1. Dietary requirements of pigs. ME = Metabolisable energy.
(Whittemore et al 2003)
Live weight of pig (kg)
60+ 40+ 25+ 15+
ME MJ/day 26.87 22.17 12.8 10.1
Crude protein g/day 310 270 219 185
Lycine g/day 25 13.8 10.9 9.5
Voluntary feed intake kg DM/day 3.5 2.5 1.75 1.25

Protein sources for pigs

A highly palatable and digestible foodstuff with high levels of essential amino acids, soybean meal is currently the principle source of protein for the pig industry worldwide. However, in light of the environmental impacts, increasing price and concerns for the future availability of soya, UK-grown grain legumes, including peas and beans, may offer sustainable feed alternatives. As rich sources of metabolisable energy and protein, peas and beans could represent a valuable nutrient source in a balanced ration with other components such as cereal grains and minerals.

The trial

In a trial managed by FAI and ORC, we aim to

a.) Document the growth rates, feed consumption and costs of pig production using a forage-based diet; and

b.) Investigate alternative, locally produced protein sources.

The second (winter) phase of the trial is currently in operation to compare dietary peas and beans with soybean meal as a protein source in a ration with 55% lucerne silage, 30% barley and 1% minerals. 57 pigs aged eight to 11 weeks entered the trial in March 2014. They were divided into three groups and were sex-segregated. Over a 14-week period, the pigs in groups 1, 2 and 3 are fed rations including 14% soya, beans and peas respectively. All pigs are weighed weekly to monitor live weight gain until the pigs reach finishing weights.

Preliminary findings

The first phase of the trial was conducted in summer 2012. Average daily live weight gains were 287g/day for weaned piglets between 10-25kg and increased to an average of 640g/day for growing pigs between 25-60kg.

Pigs fed rations with soya, beans and peas had live weight gains of 662g/day, 592g/day and 665g/day respectively during the growing phase.

Statistical analysis of this preliminary data suggests there is no significant difference in weight gain between pigs fed forage-based rations with soya, peas or beans for 14 weeks from 8-10 weeks of age.

Benefits of the beans and peas-based rations include lower costs of feed in organic systems (see Figure 2), and initial results therefore suggest these feeds may represent economically viable alternatives to soya, with additional environmental and animal welfare benefits.

organic pig production, the pig site, fai
Figure 2. Comparing feed costs from weaning to finishing of forage-based rations (soya, beans and peas)
and commercial rations (based on UK average data from BPEX).

July 2015


BPEX (2012) The impact of feed costs on the English pig industry. BPEX: Kenilworth. P 2.
Van Soest, P.J. (1994) Nutritional ecology of the ruminant. 2nd Ed. New York: Cornell University Press. P 59.

Whittemore, C.T., Hazzledire, M.J. and Close, W.H. (2003) Nutrient requirement standards for pigs. British Society of Animal Science. Pp 9, 11, 12, 24.

© 2000 - 2022 - Global Ag Media. All Rights Reserved | No part of this site may be reproduced without permission.