Cassava as good as wheat for pigs, poultry

 By Michael Dom

CASSAVA is the third most important staple crop for Papua New Guinea village farmers, with total production of over 270,000 tonnes per annum, but its drought tolerance affords an advantage under poor conditions over other crops, particularly in lowlands and coastal areas where it is a dual purpose staple crop. 

Cassava is used for feeding livestock in many developing countries where grain feeds, such as wheat, corn and sorghum, are not readily available or more costly to feed to animals, particularly for the smallholder farming sector which are the major stakeholder for food security. 

Cassava is an excellent source of energy from its starch, which makes up 25 per cent of the roots. 

Additionally, the root starch is as easily digested as wheat or corn starch in the gut of animals such as poultry, pigs and fish. But cassava roots are very low in protein. The leaves can be fed fresh, dried or fermented and can only be offered as feed in small amounts because the fibres affect digestion negatively. 

Another disadvantage with feeding some varieties of cassava is the presence of trace amounts of naturally occurring cyanide (a poisonous chemical), which becomes toxic to animals when consumed in large amounts or over a long period. 

Thankfully most cassava varieties grown in PNG contain very little amounts of cyanide and milling and drying cassava can further reduce cyanide contents.

The shortfall of protein in cassava roots can be compensated for by mixing other feed ingredients into the daily rations offered to animals. This can be achieved if a protein source such as fish meal, copra meal or mill-run is available. 

But, to enable animals to reach their full performance potential in growth and production, it is needful to include ingredients that provide a properly balanced diet. 

These ingredients may contain good proportions of other nutrients not available in a simple diet of cassava blended with a single protein concentrate. 

In addition, using too much of one protein ingredient, such as fish meal, produces other bad effects like meat tainted with fish flavour or even nutritional and gut disorders and diarrhoea caused by too much concentrated nutrient in the gut. Thus effort is made to formulate suitable diets based on the nutritional value of available feedstuffs.

NARI is conducting ongoing research for using the roots and foliage of dual purpose staple crops, sweet potato and cassava, either fresh cooked, dried or fermented form. Two technologies available to smallholder farmers are the Low/High Energy Poultry Concentrate and Ensiling Sweet Potato for Feeding to Pigs. 

Low/High Energy poultry concentrate was combined with sweet potato or cassava to make a nutritious and effective diet for broiler birds and similarly for growing pigs. 

Research has begun on a new pig concentrate especially formulated to blend with sweet potato or cassava to provide a complete nutritious feed for growing pigs. 

This work is partly funded under an Australian Centre for International Agriculture Research (ACIAR) project aimed at promoting the production of formulated feeds using as much of local feed resources and using facilities such as community level mini-feed mills. 

The pig and poultry feed research is being done to prove how effectively local feed ingredients, particularly sweet potato and cassava can be combined with protein and mineral/vitamin premixes to give the maximum growth and production performance for meat animals, namely broiler birds and grower-fattener pigs. 

This highly technical feed research involves testing of nutrients such as protein, energy and minerals in the feed, estimating how much is consumed by the animal and what is lost in the faeces and urine and then determining the proportion of consumed by the animal was converted into growth as lean muscle – meat.

With this nutritional information on different tested diets in hand it will be possible to develop more cost effective diets for other classes of animals, for example lactating sows, large fattened pigs, layer birds and even fish diets through similar experiments.

Cassava and sweet potato are two of the best-bet options for use as livestock feed, substituting around 50 per cent of the dry weight of formulated diets. 

It seems reasonable to suggest that where farmers are already growing and using the roots as livestock feed for pigs and poultry, there would be good opportunity to establish local milling facilities where the feed material could be processed, stored and delivered to farmers.

One farming development option the ACIAR feed mills project proposes is that smallholder farmers based around a community feed mill would be able to provide sweet potato and cassava to the mill for processing and storage as feed either for their own use or for sale to other livestock farmers. 

There are many other added benefits to this scheme, which include use of locally available feed ingredients or staple crops, steady incomes from growing and selling root crops to local mills, employment and income generated by the mills, improved storage of perishable roots as dried or fermented products, improved farming skills and better organisation of the supply chain of feed to livestock farm.