Better Pork - October 2004Coccidiosis: a battle still to be fought
Though we once thought we had beaten cocci in suckling pigs back in the 1980s, swine veterinarians and producers report that it is alive and well. Here's how to diagnose and treat itby S. ERNEST SANFORD
It was more than 25 years ago that I made my first diagnosis of coccidiosis (cocci) in baby pigs (neonatal coccidiosis) and, for most of the next decade, we battled cocci in suckling pigs.However, by the end of the 1980s, I thought we had won that battle. Many producers had refurbished their farrowing houses and installed raised crates over the old concrete floors. Tri-bar/tenderfoot and other plastic-covered wire flooring had become the new standard. Disinfection regimens had increased and become more diligent and sophisticated. We had moved on from using flame to kill oocysts (coccidia eggs) and almost burned down a few barns in the process.
I had actually almost shoved thoughts of neonatal coccidiosis out of my head altogether by the mid-1990s as we took on more devastating battles, like PRRS, circovirus and manure management.
In recent years, however, I've been getting a surprising number of calls or hearing increasingly about problems with coccidiosis. Articles kept turning up in journals about a disease that I thought we had pretty well licked more than a decade ago. Not so! I started asking swine veterinarians and producers if they were still having problems with coccidiosis and "and the answer was: "Yes, sir, cocci is alive and well."
Coccidiosis ("cocci") is a parasitic (protozoal) infection that usually causes scours in suckling pigs at around one to two weeks of age and is poorly or totally unresponsive to antibiotic treatments. Baby pigs, however, can develop cocci scours from as early as four days old and as late as three to four weeks of age, but most of an affected litter will scour between seven to 10 days of age.
The scour ranges from white or cream to a very typical pasty gray appearance. The infection can progress to produce a more yellowy, watery scour, causing the pigs to stay damp and have a rancid odour. Piglets continue to nurse but develop a rough hair coat, are dehydrated, depressed and become poor doers. Severity of clinical signs may vary between litters in the same farrowing room and even between pigs in the same litter. Morbidity is high but mortality is usually low, unless secondary bacterial and/ or viral infections intervene.
Diagnosis. Selection by your veterinarian of live acutely scouring pigs for post mortem and histological studies are the best way of diagnosing coccidiosis. Necrotic enteritis is seen on the surface of the small intestines (jejunum and ileum) in severe cases of coccidiosis, but this is not a consistent finding. Much more reliable is the identification of various developing asexual and sexual stages of coccidia seen microscopically in the intestinal cells of freshly euthanized pigs. Oocysts (eggs) seen on fecal examination of acutely scouring pigs are also diagnostic but, like the necrotic enteritis seen at post mortem, is an inconsistent finding.
How do pigs get coccidiosis? For years, we thought that suckling baby pigs got cocci by ingesting coccidial eggs (oocysts) deposited in the sows' feces. Not so! After numerous studies, researchers have been unable to show that sows shed the oocysts in their feces. There are at least nine different types of coccidial infections that pigs can get. Only one, however, Isospora suis, causes scours or any known disease. Various other coccidial eggs can be found in sows' feces from time to time. But not I. suis eggs.
We do know that pigs get infected by ingesting I. suis eggs off the farrowing room floor. Of course this only begs the question, where did those eggs come from? From previous scouring baby pigs residing in the farrowing room is the obvious answer. See where this chicken and egg story is going? And, no, we do not know how the first piglets got cocci in the first place.
Treatment and Control. Toltrazuril (Baycox-Bayer) treatment of baby pigs at a dose of 10-20 mg/ kg is given to each at-risk piglet. Baycox is not registered for pigs in Canada, but is widely used for piglet coccidiosis. Piglets are dosed at a time after oocysts are ingested but before scours have started, usually between three to five days of age. Historical knowledge of when the baby pigs start to scour is the best determination of the exact time to treat. Treatment of the sow, once a significant recommendation for control, is no longer recommended as the sow is not identified as a contributor to the cycle of disease. Prevention via sanitation is still the best means of control. The hot humid conditions in the farrowing house are ideal for perpetuating the coccidial cycle.
Above all else, detailed attention to proper hygiene and sanitation measures in the farrowing house are key to reducing the impact of neonatal coccidiosis. Thorough cleaning of the farrowing crates to remove all organic debris between farrowings, disinfection with bleach (50 per cent) or ammonia compounds and steam-cleaning or high-pressure hot water (>70C) are the recommended methods. BP
S. Ernest Sanford, DVM, Dip. Path., Diplomate ACVP, is a swine specialist with Boehringer Ingelheim Vetmedica (Canada) Ltd. in Burlington.
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back Sweden: Tail biting is a question of taste!
by NORMAN DUNN
An eight-year survey of slaughter swine injuries in animals from more than 300 Swedish farms by the state veterinary service indicates that tail biting is significantly lower than average in units where feed components offer more variety and taste.Average tail biting injuries recorded on-farm and at the slaughterline is 2.7 per cent of all hogs surveyed so far. But those from farms where whey -- a dairy-supplied feed component still popular with northern European hog feeders - is a major part of the rations return a tail-biting incidence of one per cent below average.
Farms that rely on straightforward barley/soymeal dry mixes, on the other hand, are repaid for the bland diet with an above average count of fighting and tail biting amongst the obviously very bored consumers. Worst of all in this context is the damage when triticale is fed as a major ration constituent. Feeders already recognize that this otherwise excellent and high-yielding wheat/rye hybrid has the disadvantage of being slightly less tasty for the hog than other cereals, but the influence on fighting injuries (a plus of just short of one per cent) is only now highlighted by the Swedish survey.
The survey shows other influences on tail-biting incidence include the number of management changes in a hog's lifetime. Animals from fully integrated farrow-to-finish units with no such changes are 0.5 per cent below the average. Interestingly, a similar reduction is achieved on farms that have solid walls between pens instead of railings.
But, as every hog feeder already knows, one of the worst influences encouraging tail biting is lack of feeding space. The Swedish survey finds that where less than 30 centimetres of trough space per hog is available with rationed feed, the tail injuries increase by more than one per cent above average.
Finally, going completely against the recorded trends in other countries, the Swedes have found that large-group feeding pens in their country lead to more injuries and a marked boost in tail biting. For each extra hog added to a 12-head group the injuries increase by 0.2 per cent. BP
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back Strategies to reduce your pigs' nutrient output
Through science-based nutritional strategies, the mineral balance on your pig farm can be substantially improved. Most of these strategies are simple to implement and can have a significant impact on nutrient output and your operation's profitabilityby JANICE MURPHY
Nutrient management on any livestock operation ultimately starts with the feeding program. There are a number of options available to pork producers interested in reducing nutrient output via manure. The nutrients of prime concern are nitrogen (N) and phosphorus (P), which also represent two of the most expensive nutrients in a swine ration. Excretion of nutrients in swine manure can be substantially reduced by a number of strategies.Improve feed efficiency. In general, the better feed efficiency you can achieve, the lower the excretion of N and minerals. Improving feed conversion 0.25 units would reduce N excretion from five to 10 per cent. Over the past 20 years, the feed efficiency of pigs growing from 25 kg to market weight has gradually improved from approximately 4.0 per pound of gain to less than 2.85 in top-producing herds Since feed efficiency is the single most important factor in determining feed cost per pig, at a cost of $265/tonne, each 0.1 unit improvement in feed efficiency can also save $2 per pig.
Reduce feed wastage. Although often overlooked, a significant amount of feed nutrients may end up in manure simply because they were not consumed by the pig. Poor feeder design, improperly adjusted feeders and feed form can contribute to major feed wastage that directly affects nutrient output. Research estimates feed wastage can range from two to 20 per cent, with typical operations at five to six per cent. In general, N and P in manure will increase by 1.5 per cent for every one per cent increase in feed waste.
If there is a noticeable amount of feed on the floor, at least 10 per cent is being wasted and, at $265 a tonne, producers are losing over $6 per pig. To limit feed wastage, producers can feed pelleted rations, pay close attention to feeder design and adjust feeders properly. A good general guideline is to manage feeders so that only 50 per cent of the bottom of the feeder is covered.
Improve feed digestibility. Proper processing of feeds is a very practical way to decrease nutrient excretion through improvements in feed digestibility. It's estimated that pelleting improves feed efficiency through increased energy and protein digestibility by 6.6 per cent and subsequently reduces N excretion by 5 per cent. Particle size can also significantly improve feed efficiency. Research at Kansas State University indicates that, for corn-based diets ranging in particle size from 1,200-400 microns, there is a one to 1.5 per cent improvement in feed efficiency for every 100-micron reduction in average particle size. Kansas State University recommends an optimum particle size for pigs of 700-800 microns. Other means to improve digestibility include using ingredients with highly digestible nutrients and using enzymes, especially phytase.
Improve animal productivity. Pigs with improved lean growth potential can have a better feed efficiency as a result of reduced fat tissue growth and higher carcass lean yield as compared to conventional pigs. Feed additives that promote lean tissue growth may also reduce excretion of N and P as a result of a better feed conversion compared to non-supplemented feeds. In addition, improvement in the herd health status, or in the thermal environment to which pigs are exposed, will lead to improvements in feed efficiency and thus reductions in mineral excretion.
One experiment estimated that converting to a specific pathogen-free herd health status can improve feed efficiency by as much as 10 per cent and, as a result, decrease N excretion by 10 per cent. The most important anti-nutritional factor in swine nutrition is phytate. Phytate P must be hydrolyzed by an enzyme-- phytase -- into inorganic P before it is available to pigs. Research shows that phytase added to the diet can improve P digestibility, allowing a reduction in the total P levels in the diet to improve the efficiency of retention and reduce excretion of P into the environment by 25 to 50 per cent.
In addition, feeds supplemented with phytase for grower-finisher pigs and for pregnant sows may need little or no supplementary feed phosphate. Currently, adding phytase does not appear to add more cost to the diet because it is offset by the savings associated with reducing P and calcium (Ca) in the diet. Despite being cost-neutral, phytase use in Ontario remains at 20 to 30 per cent of pigs marketed compared to 70 per cent in Quebec.
The bioavailability of N and P varies considerably from one feed ingredient to another. The major reason for the inefficiency of P utilization in pigs is the poor digestibility/availability of P that is present in plant products, largely because much of the P in plants is in the phytate form.
In contrast, the availability of P in animal and inorganic sources is much higher. For this simple reason, pig diets should be formulated on available/digestible, rather than total, nutrient basis. Variation in nutritional value of feed ingredients is an economic and environmental concern.
Without complete and timely ingredient analysis, there is a tendency for manufacturers to over-formulate rations, resulting in higher ration costs and increased potential for nutrient losses. Using book values (such as those available from the National Research Council) for feed formulation will not be sufficient in the future. As farmers strive to feed pigs more closely to their requirements, it will become increasing important that techniques are available to determine both nutrient levels and availabilities. Using near infrared reflectance (NIR) technology or other rapid nutrient analysis methods prior to mixing feed could allow for "real-time" feed formulation and significantly reduce safety margins of nutrients.
The key to minimizing nutrient output is in feeding animals according to their nutrient requirements. Overfeeding or underfeeding nutrients will increase output since animals will simply excrete all of the nutrients they are unable to use for maintenance and growth. Accurate estimates of nutrient requirements are essential to optimize the production system, but they are a moving target, depending on factors such as energy density of the diet, stage of development, genetic potential, sex, environmental temperature and health status.
As the liveweight of a pig increases from 30 to110 kg, the optimum concentration of amino acids and P in the feed decreases. So, introducing one or more additional feeds for grower-finisher pigs will help balance the amino acids and digestible P in the diet to the requirements of the animal and therefore less N and P will be excreted. When diets are precisely formulated to meet the protein and amino acid requirements of pigs, N excretion is reduced due to decreased dietary excess and improved utilization of nutrients.
Calculations show that by changing from one feed system (common in Ontario) to a two-phase system, the N needs would be met more precisely, resulting in a reduction in N in manure of 12 per cent.
Feeding barrows and gilts separately can also decrease excretion of N and P. It is well known that barrows eat more feed, grow faster, are less feed efficient and yield lower carcass lean than gilts. Although there is little difference between barrows and gilts up to 25 kg, differences in feed intake and growth rate may be as high as 15 per cent during the finisher phase. Because they eat less feed and have a higher lean growth rate, gilts require higher levels of amino acids and other nutrients than barrows. Different diets can be fed to match the nutrient requirements of the separate sexes more closely, resulting in savings of $1 per pig, while limiting excesses and reducing excretion.
Protein is an expensive nutrient in pig diets, so maximizing the efficiency of protein and amino acid utilization is important. Diets containing amino acids at minimum requirement (for maximum lean growth) are critical.
An experiment using chemically defined diets containing amino acids as a sole source of dietary N, showed that, with a near perfect amino acid balance, a 15 kg pig is capable of converting 87 per cent of its absorbed N above maintenance to body protein. Feed ingredients are combined to meet the pig's requirements for the most limiting amino acid. As a result, the protein content of the diet is higher than required because of the presence of excess amino acids.
For grower-finisher pigs, the greatest strides in N utilization can be achieved by improving the dietary amino acid balance, so that the diet more closely reflects the true balance in which amino acids are required. Through manipulation of the dietary amino acid balance, N excretion in manure can be substantially reduced -- by 35 per cent in grower pigs and 20 per cent in finisher pigs -- without affecting animal performance.
Synthetic amino acids are often added to swine diets. L-Lysine-HCL is the most commonly used, and DL-methionine is used in some diets. Recently, synthetic L-threonine and L-tryptophan have become commercially available.
The swine industry's ability to use competitively priced synthetic amino acids efficiently is limited by our knowledge of pigs' amino acid requirements by the biological availability of amino acids in feed. The order in which amino acids become limiting will vary with pig body weight, body protein gain and feeding level. With the current cost of synthetic amino acids, it does not make sense to include synthetic amino acids other than lysine in grower pig diets. But this will change as the availability and price of other amino acids improves.
The bottom line is that, through science-based nutritional strategies, the mineral balance on pig farms can be substantially improved. Most of these strategies are quite simple to implement and can have a significant impact on nutrient output and the operation's profitability.
The most promising and practical of these strategies focus on two main principles -- minimizing input and maximizing the efficiency of nutrient utilization. Table 1 lists potential strategies and their impact on nutrient excretion. Using phytase, replacing protein with synthetic amino acids and feeding more closely to the animal's requirements, N and P excretion in pig manure can be reduced by up to 50 per cent. Applying nutritional strategies to reduce mineral excretion will increase the need for precise feed ingredient evaluation, feed formulation, manufacturing and delivery.
Table 1. Potential impact of nutritional strategies on excretion of nitrogen and phosphorus. Strategy Used Reduction in Nutrient Excretion Improve feed efficiency 3 per cent for every 0.1 unit in improvement Minimize feed wastage 1.5% for all nutrients for every 1% reduction Match nutrient requirements 6-15% for N and P Phase feeding 5-10% for N and P Split-sex feeding 5-8% for N Phytase 2-5% for N; 20-50% for P Formulate on nutrient availability 10% for N and P Replace protein with amino acids 9% for N for every 1% reduction in crude protein Highly digestible feed ingredients 5% for N and P Pellet the ration 5% for N and P 700-1000 micron particle size 5% for N and P Enzymes: cellulases, xylanases, etc. 5% for N and P for appropriate diet Growth promoting feed additives 5% for all nutrients Low-phytate corn 25-50% for P
For more detailed information, get a copy of OMAF Fact sheet #04-035 --- Nutritional Strategies to Decrease Nutrients in Swine Manure or the 2004 London Swine Conference Proceedings.BP
Sources:
van Heugten, E. and T. van Kempen. 2001. Understanding and applying nutrition concepts to reduce nutrient excretion in swine. North Carolina Co-operative Extension Service. pp. 1-15.Ferket, P.R., E. van Heugten, T.A.T.G. van Kempen, and R. Angel. 2002. Nutritional strategies to reduce environmental emissions from nonruminants. J. Anim. Sci. 80 (E. Suppl. 2): E168-E182.
Janice Murphy is Swine Nutritionist with the Ontario Ministry of Agriculture and Food in Fergus. E-mail janice.murphy@omaf.gov.on.ca
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