Better Pork - April 2006Influenza pandemics – where does the pig come in?
Though it has been cleared as a culprit in 1918 “Spanish flu” epidemic, the pig could conceivably act as a “mixing vessel,” paving the way for new influenza viruses. Flu shots for pig and poultry workers are recommendedby S. ERNEST SANFORD
A pandemic is when a disease epidemic is global in scope, affecting populations around the world. Three influenza pandemics were recorded in the last century -- in 1918 (“Spanish flu”), in 1958 (“Asian flu”) and in 1968 (“Hong Kong flu”).
Pandemic influenza outbreaks in humans originate in nonhuman species, usually birds. They then adapt to and become deadly in humans and spread through the human population worldwide with great speed.
Pigs play a key role in transmission of influenza viruses between species, especially from pigs to humans and vice versa. The pig is characterized as a “mixing vessel” for influenza viruses, capable of reassorting segments (genes) of avian, human and swine influenza viruses and producing completely new strains of virus which can then infect humans.
Of the three types of influenza viruses -- A, B and C -- only type A has been implicated in pandemics to date. The others infect humans primarily, have not been implicated in pandemics and will not be discussed further in this article.Influenza type A viruses infect many species, including humans, pigs, birds (wild and domestic), horses, ferrets, seals and more recently, dogs.
Influenza viruses are classified into subtypes based on two antigens on the surface of the virus, one called hemagglutinin (H), the other, neuraminidase (N). There are 15 hemagglutinin antigens (H1 to H15) and nine neuraminidase antigens (N1 to N9).
Mutations of any one (or more than one) of the “H” or “N” antigens in a subtype produce further changes which are classified as strains. Influenza viruses change frequently and can then give rise to local and regional epidemics or, under the right conditions, worldwide pandemics.Mutations account for the creation of most new strains. Reassortments of genetic material between two different strains can also give rise to new strains. Both result in subtle changes that are called “drifts.”
Reassortment between different subtypes, however, can produce a brand new subtype, in essence an entirely new virus. This is a major change and is called a “shift.” These “shift” reassortments can occur among avian, swine, equine and human influenza viruses. The new viruses can have genetic material from two or more host species -- for example, avian, swine and human.This is where the pig comes in handy as a “mixing vessel.” The pig, unlike birds and humans, has receptors that can attract and bind swine, avian and human influenza viruses, thus setting the stage for opportunities for reassortments and creation of brand new subtypes in the pig.
Wild waterfowl seem to be the natural reservoirs for the type A influenza viruses since they harbour all known “H” and “N” subtypes. Avian influenza viruses are classified as highly pathogenic avian influenza (HPAI) or low pathogenic avian influenza (LPAI) based on genetic features of the virus and the severity of disease in poultry. Only the H5 and H7 subtypes have been HPAIs. H5 and H7 LPAIs also exist.
Starting in early 2004, widespread outbreaks of an HPAI H5N1 virus erupted in poultry flocks in the Far East -- Cambodia, China, Indonesia, Japan, Laos, South Korea, Thailand and Vietnam. Outbreaks then occurred in poultry in Europe -- Romania, Turkey, Greece, Russia and Croatia -- in the summer and fall of 2005. Outbreaks of the avian H5N1 also occurred in humans and occasionally pigs in many of the Asian countries.At the time of writing, H5N1 influenza infections have been documented in more than 150 people, predominantly in Asia. So far, more than 80 people have died and the first deaths in Europe (Turkey) were reported in January 2006. The activities of this HPAI H5N1 over the last two years have spawned a worldwide alert for the next influenza pandemic.
The great worldwide concern over this HPAI H5N1 comes because of its increased ability to infect humans, almost exclusively those working in close contact with infected birds. The leap over to a pandemic would occur if the virus starts spreading from person to person, directly, without them being in close contact with infected birds.
So far, direct spread among people has not occurred. However, the rapid spread of HPAI HN1 among birds and its willingness to infect and kill humans raises alarms over the possibility of a mutation which forms a strain that does spread from person to person.
It’s possible that pigs could influence this transformation. On farms where pigs, poultry and people coexist, pigs could become infected with avian and human influenza viruses simultaneously, providing the opportunity for the virus to undergo reassortment and produce a new pathogenic virus that could be transmitted to people and spark the next pandemic.Finance Canada estimates that if the bird flu pandemic were to hit Canada costs could exceed $14 billion to the Canadian economy, with 6.2 million people falling ill and 133,000 deaths.
What about H5N1 in Canadian wild birds? A national survey in the summer and fall of 2005 revealed that six per cent (251 of 4,333 birds tested) of our Canadian wild ducks were harbouring avian influenza viruses. Only Manitoba had ducks with the H5N1 strain, but it was an LPAI and not a source for a pandemic. When domestic ducks were found with the same LPAI H5N1 in British Columbia that same summer, however, two infected duck flocks were destroyed and neighbouring poultry flocks were quarantined for several weeks until tests showed that no other flocks had been similarly infected.
To end on a more positive note, while the pig was identified for most of the last century as the source of the 1918 “Spanish Flu” pandemic, it has recently been determined that that influenza virus did not come from pigs at all. Examination of the influenza virus taken from a mummified person who died from the “Spanish Flu” revealed that the virus was actually of avian origin. It is now believed that pigs actually got the “Spanish Flu” from humans and not the other way around.
Even so, public health officials are recommending that livestock farm workers, especially those working in poultry and pig farms, get their annual flu shots. This reduces the possibility of the human influenza virus spreading from humans to pigs, or vice versa, and minimizes one such avenue for new virus formation. BP
S. Ernest Sanford, DVM, Dip. Path., Diplomate ACVP, is a swine specialist with Boehringer Ingelheim Vetmedica (Canada) in Burlington. esanford@bur.boehringer-ingelheim.com
© copyright 2006 AgMedia Inc..
back How much do you really know about swine feed ingredients?
Here’s our annual swine nutrition quiz, this time to help you test your knowledge of what to include in swine rationsby JANICE MURPHY
Composing a nutrition quiz each April seems to have become a tradition for me. Maybe it’s a throwback to years gone by in college and university when April meant exams. As preparations began for this year’s test of knowledge, I started thinking about what other areas of swine nutrition were left to tackle.
The list is endless, but my attention kept getting drawn to the mountain of information that is available about all the feed ingredients we have available and how we pick and choose what to include in swine rations. Even though we tend to think in terms of corn and soybean meal here in Ontario, there are countless options out there.
As discussions continue around the issue of corn countervail and we face the potential for another challenging year of unpredictable weather, there are plenty of good reasons to look at the alternatives to our favourite Ontario crops.
So, whether you are a straight corn-soybean meal kind of guy or an adventurous try-anything-once kind of girl, here are a few questions about some specific feed ingredients and what’s involved in making those choices to get you thinking. See how you do with these… and just maybe you will reconsider your ration choices as we head into another cropping year.
Questions
1. Whole canola seed does not require heat treating prior to inclusion in a pig ration.
a) True
b) False2. Since the protein content of corn gluten is higher than corn, does that make it a better protein source for pigs?
a) Yes
b) No3. Which of the following accurately describes No. 1 wheat screenings?
a) At least 35 per cent shrunken or broken wheat
b) No more than eight per cent wild oats
c) No more than six per cent small weed seeds
d) All of the above4. Given the choice between any of the ingredients listed below, a pig would eat…
a) Rye
b) Triticale
c) Corn
d) White beans5. Livestock feed ingredients are strictly regulated in Canada by the following:
a) Feeds Act and Regulations
b) Health of Animals Act and Regulations
c) Both of the above
d) None of the aboveAnswers
1. (a) Unlike raw soybeans there is little or no nutritional advantage to heat-treating whole canola seed. Whole canola seed is a good source of protein (about 20 per cent) and has a high oil content (about 40 per cent), which makes it a concentrated source of energy. While the high oil content makes whole canola an attractive energy source, it is also what limits its inclusion rate in many rations.
For grower-finisher pigs, total dietary fat levels should not exceed 5.5 per cent to avoid issues with soft fat in the carcass. For sows, whole canola seed can provide the added fat commonly included up to 12 per cent of the sows’ feed. Practical feeding experience has shown that whole canola seed is best fed to pigs greater than 25 kilograms of weight and is readily accepted at levels up to 12-14 per cent of the diet. As an added bonus, it can help reduce dust as well.
The relatively high oil content in whole canola seed can present some challenges for processing. Vern Racz, executive director at the Prairie Feed Resource Centre in Saskatchewan, suggests mixing the canola seed 50:50 with another dry grain and grinding it through a 1/8-inch hammer mill. This not only facilitates processing but it also flows better.2. (b) Since pigs do not have a specific requirement for protein but rather for the individual amino acids that make up protein, an ingredient’s protein content is not a very good measure of its adequacy. Protein sources differ widely in amino acid content. The level of essential amino acids, specifically lysine, is a much better indication of nutritional quality than percent crude protein.
Lysine is the most limiting amino acid in typical corn-soybean meal diets. For example, corn gluten contains a high level of protein relative to the amount of lysine. If a ration were prepared with corn gluten based solely on the protein concentration, the ration would not meet the pig’s lysine requirement necessary to support optimum performance. As a result, it is important to remember that rations for swine need to be balanced according to the level of lysine, not crude protein.
3. (d) In order to be classified as number 1 wheat screenings according to Canadian Grain Commission guidelines, the screenings must meet all of these criteria -- at least 35 per cent shrunken or broken wheat, no more than eight per cent wild oats and six per cent small weed seeds (such as canola, rapeseed, wild and domestic mustard seed).
Recent research by Phil Thacker in Saskatchewan has shown that number 1 wheat screenings can be successfully used as an energy source for growing-finishing pigs and can be fed at levels as high as 72 per cent of the diet with no negative effects on pig performance or carcass quality. His wheat screenings contained over 88 per cent whole or cracked wheat with the most prevalent weed seeds being wild buckwheat and canola seed.
However, he did warn that if the level or type of weed seeds contaminating the screenings change appreciably from those reported in his research, then it may be necessary to re-evaluate the inclusion level of wheat screenings in the diet.4. (c) In the pig world, corn is considered “good stuff.” Just like humans, pigs have definite flavour preferences and unfortunately rye, triticale and white beans are not among them. Just as a child might turn up his or her nose at brussel sprouts or turnips on the dinner plate, pigs may eat less of an ingredient that is unpalatable. Since pigs have more taste buds than humans (15,000 versus 9,000) flavours, or off-flavours as the case may be, can have a bigger impact on what feed alternatives are feasible.
So, when considering alternative feed ingredients, simply examining the nutritional profile is not enough. Some consideration needs to be given to the pig’s willingness to consume it. Just because palatability is an issue, however, does not mean that an ingredient cannot be used, but limits on inclusion rates may be necessary to accommodate any negative effects on feed intake.
5. (c) In Canada, all feed ingredients for livestock (including cattle, swine, poultry, sheep, goats, horses, rabbits, fish, mink and fox) must be listed in the federal Feeds Regulations. Using the authority of the Feeds Act and Regulations, the Canadian Food Inspection Agency (CFIA) approves and controls livestock feeds and feed ingredients through a comprehensive assessment and registration process.
As an exception to this requirement, feed ingredients for poultry and swine not listed in the Feeds Regulations can be fed as Edible Residual Material (ERM) under a permit issued by the CFIA under the Health of Animals Act and Regulations. The term “ERM,” as defined in the regulations, refers to "edible material that remains after, or is not used in, the processing, manufacturing, preparing, serving or sale of food". Examples of ERM include bread, cookies, ice cream and milk.BP
Janice Murphy is swine nutritionist with the Ontario Ministry of Agriculture and Food in Fergus. E-mail janice.murphy@omaf.gov.on.ca
© copyright 2006 AgMedia Inc..
back Twenty-three steps to an improved barn environment
A check-list to help you do a better job of managing manure, ventilation and general barn healthby RON MACDONALD
To improve manure management:
1. Repair and replace penning and flooring which cause spilled water, manure or urine to lie on floors and alleyways. This raises ammonia and humidity levels in the winter and reduces the room temperature, since it takes energy to evaporate this liquid.
2. Check slats and penning support ledges for spots where manure can build up. This provides a haven for flies and causes similar problems to those mentioned above.
3. Never allow manure to build up closer than 12 inches from the bottom of the slats. Gas begins to enter the confinement area and affect performance if manure builds up beyond this level.
4. Check for leaks through manure pump-out ports or under manure pit dividers. Air entering rooms this way increases gas production from the manure and can cause extreme health problems.
5. Flush manure from gravity flow pits within 15-20 days maximum. Recharge the pits with a few inches of fresh water to absorb ammonia and reduce potential for build up of solids.
6. Ensure radiant heat lamps direct heat onto solid pads. Light passing through slats will heat the manure below and increase gas production.
To improve ventilation:
7. If there is a pit tube/duct ventilation system, be sure to check it periodically for build-up of solids and manure.
8. Repair leaking waterers immediately. Keep replacements handy.9. Verify that there is adequate flow at water nipples and check to see if there are problems during high flow times. Since 70 per cent of water is consumed during feeding, morning or late afternoon is the best time to do this. If some form of water-based cooling is used, it will mean the heaviest load occurs during late afternoon; check when the cooling systems is operating.
10. Ensure that the mechanical ventilation system is performing as required. Use a static pressure gauge to adjust air inlets; Set at 0.04 inches in the summer, 0.08 inches in the winter.11. Verify inlet openings are correct with a velocity meter, such as the Dwyer High Air Speed Indicator.
12. Ensure inlets are of good quality and properly located to mix fresh air uniformly and reduce drafts.
13. Adjust minimum winter ventilation to achieve a relative humidity of 50-70 per cent. Setting it too high causes health problems from air-borne pathogens. Too low increases heating costs and can also cause health problems. An inexpensive digital relative humidity instrument is a good device for checking relative humidity as well as temperature.
14. Verify heaters, fans and shutters and controls are all maintained.
15. If air is drawn in from the attic in summer, ensure the temperature rise is less than
1.5 C. Exterior roof sheathing should be white. Alternatively, a layer of insulation on the underside of the roof will also help to reduce solar heat gain.16. Check and maintain insulation levels. This not only reduces heat load on the building, it reduces the thermal environment effects due to reduced radiation (winter) and excessive radiation (summer).
17. Consider some form of cooling appropriate to the type of production room -- spray cooling, evaporative cooling pads, stirring fans, tunnel ventilation, earth tube cooling, and so on. A 1.6 -6.5 C cooling benefit is achievable, with a resulting improvement in feed consumption.18. Monitor temperature with a good quality digital maximum/minimum thermometer in every room. Older style mercury thermometers do not respond quickly enough.
Some miscellaneous things you can do:
19. Ensure pigs receive adequate light for at least 10 hours a day (Recommended Code of Practise for the Care and Handling of Farm Animals -- Pigs).
20. Use fluorescent tube fixtures or high intensity discharge to achieve this economically. Paint walls and ceilings white. Keep surfaces and lighting fixtures clean to ensure maximum reflectivity.
21. Consider installing windows to improve the environment for management. They add very little to heat load and can provide a psychological lift.
22. Install a good quality alarm system. It should be independent of controls, have a battery back-up and be lightning protected. It should also be managed so that response to alarm is less than 15 minutes. A back-up generator or other emergency contingency plan should be developed in advance to reduce potential for animal suffering and loss. It should operate off all minimum ventilation fans as well as high/low temperature sensors in each room.
23. Conduct a "Barn Health Audit" on the manure, ventilation, and lighting systems at least every spring and fall. Consider having independent experts to do the audit for you.BP
© copyright 2006 AgMedia Inc..
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