Uniform litters lead to better returns from feeding hogs

Friday, December 5, 2014

Feed conversion, carcass conformation and therefore profit per feeding hog are all greatly influenced by sensitive sow management during gestation – but especially in the first four weeks post-insemination

by NORMAN DUNN

We all know that piglets with birth weight below litter average never really catch up. In fact, Swiss research underlines that underweight litter members actually waste feed through poorer conversion, dragging down the profitability of the whole batch.

The Agroscope research institute at Liebefeld-Posieux (ALP) preaches the gospel of uniform litters as the most sustainable solution to better returns from feeding hogs. Genetic development towards larger litters, points out the ALP swine husbandry department, brings more birth weight variability. Trial results show that the closer birth weights lie together, the lower the losses are. Average feed conversion during subsequent feeding is always better with a uniform litter. Not only that, there's also a higher proportion of the most valuable cuts per carcass. Achieving more uniform litters means looking even closer into foetal development.

ALP research in this direction indicates that poor intrauterine development leads to piglets whose growth has been retarded since embryo stage attempting to compensate later by building muscle with larger muscle cells than those found in normally developed litter mates. But this larger cell muscling ability is naturally limited with higher feed intake often diverted into fat production. On top of this, ALP finds that large-cell muscling has inferior eating quality.

So, how can uniform embryonic development be influenced by the hog farmer? All research so far puts stress as a leading factor negatively affecting litter uniformity. Stress means not just bullying in the sow group, or even rough handling by humans. It is also a product of low, or too high, housing temperatures, thirst or hunger.

In the first month after serving, the establishment of fertilized eggs in the uterus can be negatively affected by stress. Main causes of poor establishment include patchy re-establishment after previous farrowing of the uterus mucous lining (endometrium). This leads to some areas of the lining offering optimal attachment conditions and others giving only scant "bedding" conditions. The result: insufficient development of fertilized eggs and therefore uneven litters. Excess stress for the sow can also affect ovulation. Slowing this process down also gives embryos of differing sizes.

Naturally, no one really needs to tell the experienced stockperson to take it easy with newly inseminated sows – and to make sure they are eating and drinking enough after the intensive suckling period. Nowadays, though, we have to accept that genetic progress, with its inbuilt result of larger litters, can naturally lead to a wider variation of birth weights. This is not making things any easier on this front.

Neither are welfare introductions in Europe stipulating that inseminated sows have to be running loose in groups just a few days after serving. Both factors mean more stress for the newly inseminated sow. Maybe what's wanted now are more breeding programs towards stress-resistant, placid temperament breeding female lines.

Shredded paper as bedding for piglets?
Outside the piglet creep box, it can be pretty cold at ground level in slatted floor farrowing pens, especially in older, poorly insulated, sow barns. Aberdeen University student Elizabeth Dalton measured averages between around 18 and 21 C in the pens of a Scottish 440-sow unit during and after farrowing. Temperatures could drop to below 13 C, this honours degree student found, during the morning control and feeding period.

Floor areas towards the rear of farrowing pens are especially cold – much too cold for piglets immediately after birth. Observations show that, if piglets land in this area after birth, they very rapidly lose body heat and therefore the will to struggle to the mother's udder for colostrum. This loss of vitality means they easily stray in the vicinity of the sow and are not lively enough to react and avoid crushing.

In cold barns, Dalton and earlier investigators have found that almost 50 per cent of pre-weaning deaths are caused by crushing or by other sow-caused injuries (although this figure seems to include high crushing incidence from U.K. outdoor, unsupervised farrowing with the respective figure for indoor farrowings nearer 20 per cent).

The birth period and immediately afterwards are the most risky times in this respect. Making shredded paper particularly attractive as an insulation material along the sides and rear of farrowing crates is the paper's texture and warmth, which seem to attract newborn piglets and draw them away from the immediate vicinity of the sow.

A trial carried out on the family farm of Alison and Danny Skinner in Insch, Aberdeenshire by Dalton showed that bedding each farrowing pen with two to three kilograms of shredded paper did indeed tend to keep piglets away from the danger zones and resulted in fewer litter members being lost through crushing. In fact, out of a total of 589 piglets born alive to 40 sows in the trial with shredded paper, 20 were lost through crushing. A similar-sized farrowing group (599 born-alive piglets) in pens with no shredded paper suffered crushing losses involving 38 piglets.

Extrapolating this benefit to the entire herd over a year equals 392 piglets saved from crushing. Taking a gross margin equivalent of around C$35 per 80 kilograms liveweight hog, this adds a potential extra $14,000 to herd income. Shredded newspaper is deliverable at around $590 a ton in northeast Scotland. Bedding all farrowing pens over the year would therefore cost the equivalent of $1,360, giving the Skinner sow herd a realistically possible annual bonus of more than $12,500.

Shredded paper as insulating bedding on concrete slatted farrowing pens has been recommended by other research institutes, with previous successful trial results in Scotland and Ireland. Farrowing pen floors could certainly be insulated more economically with straw bedding, for instance. But more material per pen is usually needed to offer the same degree of insulation and straw is labour-intensive to apply around the farrowing crates, tending to block slats and slurry pumps. Straw can also pose a dust problem for stock and stock persons.

Paper, on the other hand, is normally dust-free and disintegrates within 24-36 hours, falling through the slats with no further hassles. Paper currently looks good as an insulating alternative in this context – as long as its price as a recycling material remains at present low levels.

Faster healing with infrared creeps
The University of Veterinary Medicine in Hanover, Germany, has announced that using infrared creep heating plates appears to speed up the healing process with piglets – for instance, drying off their umbilical cord, tail removal wounds and castration scars, as well as helping healing with the usual bites, scrapes and scratches incurred by members of a lively litter.

Tested by the veterinary university in piglet creep areas were infrared plates and warm water heating plates, in each case with and without a creep cover. A total of 187 litters spent their suckling period in one of the four variations and results processed to find the most effective system.

It has to be said right away that no significant piglet performance differences were found between the groups using the infrared and water-heated plates. But researchers observed a faster healing process, probably because blood circulation in the affected areas is encouraged by the infrared heating.

Piglets did not favour infrared heating plates over warm water ones for lying on or near. But one distinct advantage for infrared creep heating could not be explained by the researchers. They found that, in 89 per cent of farrowings involving this creep heating, the sows chose to farrow in a position where the udder faced the creep. This made the finding of the teats in the first hours much easier, and less risky, for piglets coming out of the creep. Average heat given off from the infrared plates was slightly higher than that of the warm water ones at 32.6 C against 31.1 C. Heat distribution from the water system was more uniform, according to the Hanover researchers, with the carbon fibre construction of the infrared plates transmitting heat rather more unevenly.    

Where covering the creep really paid off was in reducing crushing losses. These amounted to four per cent for infrared heated litters, three per cent for warm water heating and 5.6 and 6.7 per cent respectively where no creep cover was used. These results were only recorded during the summer.

In the end, the infrared system turned out no cheaper to run than the warm water heating systems. But the infrared application more than paid for any extra costs, felt the researchers, through the quick-healing effect for piglet wounds during suckling.

Slats don't automatically lead to leg problems
Hollywood filming techniques have been brought into British hog production research – and have given slatted floors in swine housing a much better welfare image.

Dr. Sophia Stavrakakis applied Video Motion Capture (VMC) at Newcastle University's School of Agriculture, Food and Rural Development to give three-dimensional film recording of changes in hogs' gait, focusing on the angle of the joints and length of stride. This system is already used to record human expressions and movements and transfer them onto animated images as in James Cameron's Avatar, the epic Lord of the Rings or the latest Dawn of the Planet of the Apes.

Now the technique is being applied at Newcastle University to give very early warning of hog lameness. First results indicate there's no great difference in terms of foot and leg health for feeding hogs on straw-bedded floors and those on the traditional solid/slatted concrete or fully slatted flooring, the systems traditionally cast in a pretty dismal light by animal welfare organizations.

The Newcastle study took 12 male and the same number of female feeders and captured their walking movements using VMC five times over a six-week period. The animals were in three groups on the above-mentioned flooring from 37 to 90 kilograms liveweight.

VMC showed that hog gait did change naturally over the feeding period, but that there were no significant effects directly attributable to the type of flooring. Many of the recorded changes are described by Dr. Stavrakakis as "very subtle and therefore undetectable to the human eye." She adds: "This shows that the three-dimensional motion capture technique may be useful for future detection of subtle leg weaknesses and lameness in hogs."

Such early warning applications are welcomed in Britain with its 400,000-sow national herd, where lameness loses farmers an estimated C$9 million annually, according to the British Pig Executive (BPEX). BP