9. Raising pigs in a village pig house.

These little pigs lived in a house of sticks…built to withstand a cyclone

There is every reason that small groups of pigs will grow well on small holder farm sites. Once the matters of feed quality, health and genetics are covered it’s only a matter of space, water, hygiene, air quality and warmth when they're young.

Pig house near Tari.

The last wasn’t an issue in tropical Port Moresby.  We had water on tap, and while it could be an issue in the highlands we had good bore water on Farm Alstonia. 

It was just a matter of building a pig house.  We had seen village pig houses on our trip to Hela province. They had mostly been built of scrap materials.  The floor boards had gaps wide enough to almost swallow a small pig or at do serious injury if a foot went through.  The wall boards or mesh went all the way up to the roof to prevent theft.  

Water was provided once or twice day in buckets.  It might have been OK for one pig but not ten at a time and not for the 16-20 weeks it would take to get them to market.  We needed ten pigs to provide

A row of pig houses near Tari

some economies of scale for transport, premix delivery and supervision.

I’d seen plenty of purpose-built pig houses in Laos, East Timor and Vietnam.  These had been made from local materials.  They had thatch roofs.  Some had woven grass walls. Some had wooden floors made from battens with slots between them to allow urine and faeces to fall through. Some had concrete floors that could be cleaned each day with a shovel or a hose when pressurized water was available. 

Milled timber from a walkabout saw mill

In the highlands we had seen contractors working with portable “walkabout” saws cutting logs with fine precision so, given the ready availability of timber in the highlands, wood for a few pig houses didn’t seem to be a limiting factor. 

I asked the farm staff to build two pig houses.  After all, when we moved to the highlands, the villagers there would build the pig houses. Each one would hold 10 pigs from six weeks of age to 22 weeks of age. They needed a total of about 10 square metres of floor space and the preferred dimensions were 4500*2250 – twice as long as they were wide to encourage dunging at the right end.  

Madeleine's pig house drawing. 
Roof to catch rain, tank to store it.

After several weeks of inaction, I pressed the matter. Our staff said it was outside their skill set. “The best thing to   do," they said, “is hire some local builders.”  It wasn’t quite what I had in mind.  I wanted a building that could be easily erected by relatively unskilled people but there were plenty of builders around and it proved to be the path of least resistance.  The builders agreed to take on the job , but they wanted a drawn-up plan.

It was a reasonable request, so I drew up a rough outline and took it to Madeleine, who ran her own construction design house in Geelong, to draw up and prepare a cutting list.  She had majored in development studies at uni and was keen to be involved. After several iterations it looked OK and work started in earnest.

The village pig house.  

We hunted around local timber yards for quotes and Lester, the assistant manager, eventually found one that could supply all the 150 x 150 mm posts and other timbers as per Madeleine’s specifications.  In some way this simple building, was better constructed than most people’s houses.  It could withstand a cyclone.  We limited the number of different timber dimensions for simplicity in sourcing the wood.

 I knew that the villagers, would take short cuts but I was pleased that they could see what I had in mind – if only to impress upon them the importance of space allowance per pig, hygiene, proper floor surface and air quality.  If these principles were followed in the longer term it didn’t really matter what the building looked like.  

The building was designed to be flexible.  It could easily house ten growing pigs, five pregnant sows, or a sow and her litter from farrowing to weaning and it was big enough and strong enough to be a mating pen for a sow and boar. If villagers found they liked this way of raising pigs and were successful they could build a little row of these pig houses side by side as the business grew. My pig house design was for a space for ten growing pigs, but I elected to put two houses sides by side so our two pens side by side held 20 pigs. The pens in my design also had a corrugated iron roof so that water could be collected off the roof and stored in tanks. The floors were raised about a metre off the ground to provide a bit more air circulation for the tropics and make it easier to load the animals ready for sale onto trucks.

The residents of the village pig house at home.  

There was a great deal of enthusiasm for the construction and cutting the timber. I’d talked through the plans with Lester, the assistant manager.  He was a competent fellow and very capable of supervising the builders.  Along the way I learned that Kulaka, a Huli man, who worked on the farm, had made the thatched roofs on several of the farm buildings. A thatched roof would be perfect for the hot Port Moresby climate, so we changed the plans.  The builders used the timbers bought for the original plan and improvised.  As it turned out they used the timber intended for the floor slats for the thatched  roof supports.  The planks used for the side walls were also judged suitable for the slatted floor. It wasn’t ideal for the longer term because they  would quickly wear out, but they served us well for the two years of the project.

The completed pig house looked terrific. Staff loved it.  They said, “It is far too good for pigs. It should have been a bar in a resort hotel.”  The pigs did exceptionally well.  It was cool, the staff and the pigs kept it clean, we installed a drinker at one end and made a feeder out of a car tyre but staff preferred a big tub as a feeder. None of the pigs in the village pig house caught swine dysentery, a diabolical enteric disease, which was rampant in the main pig shed just a few metres away.  While many others in the main farm were sick over an extended period, these pigs didn’t miss a beat.

Figure 1. Performance of different groups of pigs
based on size in the village pig house.  The bench mark is the
trial pigs fed silage - yellow dots

We put the pigs into the pig house when they were six weeks of age. They had been weaned at 4-5 weeks and spent the next 1-2 weeks in the weaner pens in the main building before being moved to the pig house next door. The pigs themselves were the progeny from our trial gilts.  At this stage the trial gilts had grown to maturity, cycled, were mated, and farrowed successfully in sufficient numbers for us to select 20 pigs to feed the fermented cassava diet and see if we could reproduce the trial result in a different environment. This time they would be fed the diet from six weeks of age as opposed to starting at about 12 weeks of age in the trial. Would the pigs be able to eat enough to grow well?  I was worried that the feed intake of the young pigs would be limited by appetite; that they just couldn’t eat enough cassava silage to get the nutrients required for maximum growth performance.  Their stomachs wouldn’t be big enough.  But maybe, while they would grow a little more slowly to begin with, they would catch up a bit and at the end not be far behind in weight compared to pigs raised on commercial diets. 

We had to be careful about the little pigs. The “Magic Mix” protein- vitamin- mineral supplement was based largely on soya beans. It was OK for older pigs but not so good for those less than four weeks of age.  Our long-term plan was to raise the pigs on the sow farm until they were six weeks of age and then send them out to the villages when they were past the high-risk period immediate post weaning. 

The pigs were about 12 kg and six weeks old when we moved them in.  They were fed a fermented cassava silage diet containing Magic Mix at 30% of the diet until they were about 14 weeks of age. After that we fed them the premix at 25% of the diet. In the third trial, (commencing February 2015) we changed the protein premix (now called magic mix 2) and fed it at 12.5% of the diet until 14 weeks then at 10% of the diet until about 22 weeks of age. Unfortunately, due to Murphy’s Law, we were only able to measure the pigs for the first 100 days of the trial, but it looked like the reformulated, more concentrated Magic Mix 2 worked OK.

How good is cassava silage to eat?

In earlier trials we found the pigs enjoyed the cassava silage as much as the kau kau (sweet potato) silage.  The nutrient content of the two ingredients was so similar for there to be no difference in nutrient intake and hence likely performance. Water availability, quality and feed mixing errors were likely to have a greater impact on performance than any small differences in nutrient intake arising from feeding one tuber over another. Weight and age and body dimensions of the pigs are presented in the   accompanying figures. The data collected from the first pen trials were used as standards for comparison. It all worked rather well.  The pigs thrived in their pig house and we ran three batches through. The data for the first trial are presented in Figure one.  The average performance of the pigs (grey dotted line) was less than in the main trial (yellow dotted line) but in that main trial the pigs went onto fermented sweet potato silage at about 12-13 weeks of age. The difference wasn’t big enough to matter.

In the village pig house, the pigs were fed fermented cassava silage from about 5-6 weeks of age.  Given the limitations of appetite and hence nutrient intake in the young pigs it is not surprising that they grew a little more slowly. Not unexpectedly the biggest pigs grew faster than the smallest pigs.  What did surprise us was that the pigs later fed the more concentrated premix diet (Magic mix 2) at 12.5% and 10% of the total diet grew very well indeed.  These pigs needed to consume more of the silage diet than had been the case in the trial to meet predicted energy intakes.  The sheer bulk of the diet might have been expected to reduce nutrient intake, but it appeared to have no adverse effects. Across all weights and diet groups the

shape of the growth curve was about the same.

In addition to checking weight and appetite we also measured the pigs.  Our thinking was that, based on figure two, if the pigs were normal and healthy, from 110-170 days of age their age would provide a reasonable estimate of weight. However, some extra precision would be valuable in picking early problems.  We used body dimension, primarily heart girth, as a proxy for weight. There would be no scales in the villages, so heart girth became an important predictor of weight for us. 



The relationship between heart girth and age was linear from about 110 days of age, Figure 4. In a separate group of 20 pigs grown out in the pig house the slower rate of change in heart girth is shown in the younger pigs. The curve is pretty much the same shape as weight. Adding length into the equation wasn’t much extra help and just made recording more complex.

Figure 5 summarises data from four groups of pigs.  The data from the batch in April 2014 show the highest and lowest performers. The average is summarized by the yellow line.  The dotted blue line charts the performance of the group fed the 10% premix (Magic mix 2) from 42 to 105 days. The red 
line records the performance of the silage fed pigs in the first controlled trial.  Figure five shows an obvious anomaly demonstrated by the dashed black line in the September 2014 batch. These pigs were grown through periods of serious water restriction that will have affected food intake.  The pigs had been growing so well until 100 days that they could have been expected to maintain that performance but water supply problems plagued the farm during September and October. 

Fig 6.  Heart girth as a predictor of weight

Figures 3-6 show that an estimate can be made future heart girth and weight from a single measurement taken after 80 days of age. Based on heart girth at 80 days of age, heart girth at 150 days can be predicted. However, the standard deviation falls between 2.2 and 8 (it averaged 5,) so it is a blunt instrument for assessing the weight of animals close to sale. For example, at about 150 days of age, a pig with a heart girth of 95 cm will weigh between 86 and 99 Kg. Perhaps we should have measured heart girth more carefully.

The three batches of pigs, fed a cassava silage diet supplemented either with a 10% (Magic mix 2) or 25% protein mineral premix, depending on age, grew consistently and within the expectations generated by the controlled trial.  The pigs in these batches were fed the cassava diet from a much younger age (six weeks) than in the controlled trial (12 weeks) yet they performed well. I think the well ventilated wooden pig house, its simple design and space allowance contributed to the performance. Major limiting factors such as poor air quality or high stocking density were avoided. The pigs were kept scrupulously clean.  

Figure 7.  The redesigned pig house for the highlands

The success of the pilot study provides confidence that pigs can be raised successfully in the highlands on similar diets.  There, of course, it is likely that a kau kau silage diet will be fed. In addition, small changes in the pig house design will be required to protect the pigs from the lower highland nighttime temperatures.  To this end a cover over the end of the pen while the pigs are small will be necessary.  Further, because it is cooler, it will not be necessary to raise the pen, so a concrete floor can be installed at ground level and manure removed by hand, composted and added later to gardens.

Figure 8.  Doug Pope's model pig house

Given the experience of building the first pig house in Port Moresby and recognizing that the Hela villagers might elect to build the pig house themselves and without adherence to any specific plan I asked my friend (the late) Doug Pope, a pastry chef par excellence turned local handyman, for guidance.  “How would you go about this?” I asked. “Make detailed model,” he said. “One that you can look at and see what’s been done, that you can take a measurement from, and scale it up. One where the bolts can be seen.  Where you can take the roof off and see the beams, rafters, battens and reinforcing to stop it from falling over”.