Sweet potatoes and pigs in the nation

 By Michael Dom and Workneh Ayalew

Sweet potato is our most important food crop and pigs are our most popular livestock. Pig keeping is an important part of Papua New Guinea lifestyle, particularly for traditional exchange purposes.  

In the predominant smallholder mixed pig and sweet potato production systems, sweet potato provides human food and pig feed.

This dual purpose role creates an apparent competition between humans and pigs for the tubers. This means that incremental use of the crop for either of these purposes imposes trade-offs in its potential uses for the other purpose.  

Introduction of improved tech­nologies into the traditional sweet potato-pig system can generate productivity gains at farm level in the form of higher root and vine yield and reduced wastages at harvest. Furthermore, preservation and storage of excess tubers and vines for extended use after harvest can add value to garden forage. 

Village farmers regularly pro­vide much of their excess sweet potato production to pigs, like other garden produced feeds such as cassava, coconuts and fresh forages. 

The forage is offered to pigs either cooked or fresh and this practice has not changed for many generations.  The practice has worked well for subsistence needs. But subsistence food supply and social security are no longer the primary objectives for many livestock farmers who want to improve their livelihood options in PNG’s emerging modern cash economy.

The demand for meat products is rising because of increased incomes, urbanisation and expansion of the middle class population owing to the rapidly growing mineral and gas resources.  

A growing formal market pro­vides incentives for better quality of meat in the form of higher market prices. While this scenario offers opportunities for small-to-medium livestock enterprises to grow, it presents three key challenges: 

• Can the natural growth of large scale commercial livestock farms alone meet the fast growing demand for meat; 
• how can smallholder pig far­mers actively participate in the formal market supplying consistently standardised products, and, 
• How will the general public be affected by these changes in supply of and demand for meat, and will the local prices of meat remain affordable to the consumers? 

Pigs are a source of very popular meat protein in the country, more so in the highlands. But like other animal meat products much of the pork available in supermarkets is either produced by large scale piggeries or imported cheap cuts. 

Local small-scale pig farming has not been able to provide pork competitively to the formal market due to limitations in production, uncompetitive cost of production, and restricted marketing that create inconsistency of supply and poor quality product. There are existing supply-chains for sweet potato as food at local markets and this is a potential source of livestock feed. 

It is expected that improved efficiency and productivity at farm level, making full use of the dual purpose sweet potato can lead to increased efficiency and profitability for both livestock and crop farmers. 

It is estimated that only a very small proportion of sweet potato in the highlands provinces is actually traded at major urban markets. It is estimated that only half of the three million tons of sweet potato produced annually is consumed by human. Thus the other half is either fed to pigs or wasted.

From the perspective of livestock farming, it is reasonable to suggest that local sweet potato production may supply adequate forage feed, as tubers, fresh green leaves and vines for pig keepers. This is apart from sweet potato supply for household consumption or sale. 

NARI has undertaken studies to develop improved livestock feeding systems, using lo­cally available feed resources to provide options for smallholders who could not afford commercial feeds to raise their livestock.

Some breakthrough has been made from these studies which saw the release of an adapted technique for ensiling of sweet potato for storing and feeding pigs. Ensiling or ensilaging is a method of processing, packing and sealing fresh forage material for long term storage. 

Sweet potato and cassava contain sugars and starch which result in high quality silage feed after fermenting in airtight silo bins for two weeks and can be stored perfectly for long periods after harvest.

A new project is now testing a protein concentrate mixture that perfectly complements sweet potato and cassava as either boiled or ensiled or as a dry meal blended at up to 50 per cent of the daily feed offered.

The results of pig feeding ex­periments to date show remarkable test diet performance for grower pigs of crossbred commercial and local mixed genotype pigs growing from 25 to 60kg body weights. 

Using local feed crops and the concentrate, which is composed of over 80 per cent locally produced protein feed stuffs, means that the costs of feeding are very likely to be reduced, particularly if farmers are growing SP or cassava feed crops on their own land.

NARI will continue to advance research and development of livestock feeding systems to help smallholder farmers in the country. For details on the livestock feed systems, contact the livestock research and development coordinator on telephone (675) 478 4200 or email to [email protected].