Better Pork - August/September 2002How endemic diseases affect pig performance
As the immune system goes to work, it consumes more protein than can be provided by feed intake and the body is forced to break down muscle to meet the system's amino acid needs. Result: poorer growth performanceby JANICE MURPHY
At the Second Annual London Swine Conference, Dr. Gary Dial spoke eloquently about the costs, consequences and control of endemic diseases in the swine industry. He believes that "we have entered a stage in the competitive evolution of the pork industry when we are being forced to consider any technology promising an advantage either in terms of cost management or revenue enhancement."Thankfully, genetic selection has enabled the industry to take advantage of recent, promising scientific advancements in nutrition and health, so the majority of producers know how to feed pigs and manage the influences that health has on nutrient utilization.
One area not well understood, at least until recently, is how endemic diseases affect the pig. Recent research has demonstrated that endemic diseases negatively impact pig performance without causing obvious clinical signs of disease. Infectious agents induce an immune response designed to remove the offending agent from the body. In turn, the immune system gives rise to a cascade of effects, many of them detrimental to growth, on the pig's metabolic system. Experts in this field suggest that technologies which minimize activation of the pig's immune system will enhance the rate and efficiency of growth and improve lean deposition in the carcass.
A series of experiments have been conducted investigating the effect of diseases on metabolism and immune function. These studies show that, during a health challenge, immune substances cause a metabolic response to the infection that shifts nutrients away from tissue growth to support the immune response. Even when the challenge is subclinical in nature, the effect is sufficient to disrupt normal metabolism and cause losses in performance.
Exposure of an animal to any substances, whether pathogenic or nonpathogenic, results in an immune response from the inflammatory cells in the blood and tissues. The substances that are released activate the immune system, causing reduced appetite, an increase in basal metabolic rate, a shift in how both ingested and stored nutrients are used by the body and the possibility of a slight elevation in body temperature. However, sometimes there is no obvious sign that disease is present.
Table 1
Class Observations Examples Type 1 Largely eliminated from herds of Actinobacillus pleuropneumonia progressive producers Swin dysentery No excuse for producers tolerating Pseudorabies these types of infections Mange Lice Type 2 Producers currently under pressure, PRRS for economic reasons, to eliminate Mycoplasma hyopneumonia these types of infections Type 3 Future targets for elimination Salmonella cholerasuis Economically important Ileitis More difficult to eliminate from Swine influenza virus and/or keep out of herd Hemophilus parasuis Actinobacillus suis Streptococcus suis Type 4 Producers will be forced, by market Human pathogens forces and legal pressures, to eliminate ie. Salmonella DT104 Relatively inconsequential to the pig
Source: Dial, G., Rademacher, C., Wiseman, B., Roker, J., and Freking, B. 2002. Costs, consequences and control of endemic diseases. Proceedings of the London Swine Conference. April 11-12, 2002.When animals are challenged by disease, protein synthesis decreases while protein breakdown increases. The balance between synthesis and breakdown shifts toward breakdown as a result of at least three things:
Therefore, protein losses during an immunological challenge are greater than can be maintained by feed intake, an effect that is compounded when feed intake is reduced.
- Feed intake is reduced as the body's supplies of amino acids are gradually consumed while its defenses fight the infection.
- The immune response requires the consumption of amino acids to provide the building blocks to make immune compounds, such as antibodies.
- The amino acid composition of muscle does not match the amino acid needs of immune products, so the body is forced to break down a disproportionate amount of muscle to meet the amino acids needs of the immune system.
In addition to skeletal muscle, the intestinal tract may also provide a source of amino acids to mount an immune response. Research in other animals has shown that the body can initiate protein breakdown to pull nutrients from tissues having a lower priority, making them available for use by the immune system. In essence, the body will literally consume itself in the process of prioritizing resources in its fight against pathogens. In addition to effects on protein synthesis, the processes initiated by an immune challenge cause major shifts in fat metabolism. Typically, as energy is consumed during periods of immune activation, fat reserves are broken down as a source of energy to feed the immune system.
As a consequence of the metabolic and physiological effects of disease, pigs endemically infected with disease agents suffer from poorer growth performance, as reflected in reduced average daily feed intake, average daily gain and feed efficiency. In addition, the dietary lysine requirement to maximize performance is greater for pigs that are healthy compared to those that are experiencing endemic infections. Challenged pigs require supplemental lysine due, in part, to poorer digestibility (as a result of intestinal wall damage) and, to a greater extent, to an inability to efficiently deposit protein.
All pathogens that cause an immune response have the potential to disrupt metabolic processes and interfere with nutrient utilization. Dr. Dial classes diseases into four types (see table). He speculates that, as each of the Types 1, 2 and 3 diseases is eliminated, there will be a gradual improvement in growth performance and, potentially, associated increases in carcass value. He anticipates that, as preventative and therapeutic treatments are reduced, facilities are used more efficiently, productivity improves and costs of production will decline in tune with the elimination of each endemic disease. BP
Janice Murphy is swine nutritionist with the Ontario Ministry of Agriculture in Fergus. Email: janice.murphy@omafra.gov.on.ca
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Better Pork -August/September 2002
Self-policing our industry: Can it work?
Anti-hog farming pressures must be resisted, says the author. Most of us can achieve this without onerous bylaws, expensive new technology or changes in our way of lifeby SAM BRADSHAW
A municipal councillor recently asked me to make a presentation to council, which was trying to fashion a nutrient management bylaw for the community after a hog farmer inquired about a building permit for a small expansion. In considering what I would say to council, I began to reflect on how we are perceived by our neighbours. I also wondered why such a small request would send council into such a panic. This kind of alarm is happening frequently these days, resulting in moratoriums or very restrictive by-laws.To tell our side of the story, we at Ontario Pork have embarked on a determined and much-needed campaign called "Farm to Fork" designed to inform the public about the many initiatives hog farmers have undertaken. This campaign has yielded many positive responses along with some negative ones. Our story is a good one, but as some who have responded to these ads say, we have to walk the talk.
Some municipalities have adopted bylaws aimed at stopping the construction of perceived large barns and liquid manure storages, and some have zeroed in specifically on hog operations. For example, one bylaw states:
"No new liquid manure facilities or expansions to existing liquid manure facilities or replacement of existing or destroyed liquid manure facilities shall be permitted in this municipality. The owner of the livestock operation shall own not less than 60 per cent of the required land base, and the total required land base in a nutrient management plan shall be located within four kilometers of the livestock operation."
Another says: "Within the boundaries of this municipality, no land or building shall be used for an intensive hog operation." (Intensive is any building housing over 600 hogs). Yet another one says: "No livestock operation can exceed 600 livestock units on one site (2400 finisher hogs), and the operator must own 30 per cent of the land used to spread manure."
These municipalities are reacting to pressure from some of their ratepayers to do something about perceptions that hog operations are not environmentally sustainable. And in many cases the ratepayers are reacting to negative articles in the press, although some are responding to real instances where a farmer has had a spill or has not followed proper practices when applying manure.
Some farmers do apply manure excessively, or apply manure beside a neighbour's house or close to a school without incorporating it quickly. Most often, farmers are simply unaware of the impact of their practices, or are doing things the way they have always done them.
Restrictive bylaws will not likely correct these situations, but many municipalities see it as the only way to satisfy a very vocal minority. Farmers operating in these municipalities are finding it very difficult, if not impossible, to make a living and farming in such areas is not the proud profession it should be.
Recent polls have indicated that hog farmers in particular are losing ground in the eyes of the public and, whether we like it or not, public pressure can add considerable complexity and cost to our already difficult job of farming.
Based usually on misinformation, or having seen someone following bad management practices, some would have us do a hydro geological study not only around our barns and storages before building but also in our fields before spreading manure. Others want fields where we are spreading manure posted, as pesticide applicators must do in town. We are resisting these and many other suggestions, but there is strong and constant pressure exerted on policy makers to make these things happen.
For every one farmer disregarding best management practices, there are a hundred doing it properly. The problem, as always, is the one or two bad apples who spoil it for the rest of us.
Helen Johns, the new Ontario agriculture minister, was quoted as telling a group of farmers that "ninety-nine per cent of farmers are good stewards. I'm going to take the one per cent out so the rest of us can live together in peace and harmony. When you see your bad apple friends in the neighborhood, tell them I'm coming after them."
I think the Minister means business, and she needs our support. The Ministry of the Environment already has a "hot line" that the public can use to report a neighbour when they see someone doing something not up to standard. They also have a Spills Action Center where spills can be reported.
These are necessary, but I believe there are other more effective methods to achieve environmental sustainability. Teachers and doctors regulate themselves, and I believe we can do the same.
One way to handle a situation (where it is evident that a fellow producer is not breaking a law) is to actually stop and talk to the person. Most people will skirt the issue by reporting an incident to someone else, rather than facing it head on, by talking to the offender. Try to find out what it is they are doing, and if they are, for example, obviously over-applying manure or irritating someone by an apparent lack of concern. Make them aware that society is watching and that their practices are affecting all producers.
We have already achieved some success in this area of self-policing by advocating that upper-tier municipal councils set up what Ontario Pork calls Community Environmental Response Teams (CERTs). These teams respond to complaints where no environmental laws have been broken. In municipalities that have adopted this approach, CERTs respond quickly to an environmental complaint, gather facts, attempt to mediate a solution, and report back to council. These teams have been quite successful.
Some complain that CERTs have no enforcement powers. But, under the proposed Nutrient Management Act, an operator unwilling to co-operate would be subject to enforcement by the Ministry of the Environment. Peer pressure can work in areas where bylaws cannot.
Some complaints are not straightforward and require technical expertise. Where a complaint deals with an issue of a highly technical nature, perhaps Provincial Environmental Response Teams could be developed. These teams could be composed of specialists from the Ministries of Agriculture and Food and Environment, industry and commodity groups. These teams must be well trained and be able to respond quickly.
An appeal mechanism must also be established to allow for judgments or penalties to be disputed in specified circumstances and resolved in a timely fashion. The Farm Products Appeal Tribunal or the Environmental Review Tribunal could handle these situations, provided personnel are added to the tribunal that are knowledgeable in normal farm practice and agronomic principles.
This shortsighted anti-hog farming trend must be turned around. It is up to all of us to achieve a balance between environmental sustainability and economic stability. Most of us can achieve this without onerous bylaws, expensive new technology, or changing our way of life. Generally, all we need to do is make sure that we are applying manure properly, that that our barns and manure storages are built and maintained properly and that we get to know our neighbours, and treat them with respect.
I know this next part will be difficult, but let's not be afraid to tell everyone who will listen what a good job we are doing. BP
Sam Bradshaw is environmental specialist with Ontario Pork.
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Better Pork -August/September 2002
How do sorting methods affect pig performance?
Experiments performed at Akey Research indicate, among other things, that sorting of at-risk pigs at weaning and applying specialized care is strongly recommendedBy KEN PALEN
For years, swine management experts recommended sorting weaned pigs primarily by body weight into nursery pens and then budget feeding pigs according to average weight of the pen. Concerns with fallback pigs, especially in pens of large pigs, raised questions as to whether this was the best way to sort pigs at weaning. To answer this question, our colleagues at Akey Research in Lewisburg Ohio, conducted two experiments evaluating the impact of sorting method on nursery pig growth performance and resulting variation in closeout weight.
In Experiment 1, which involved 880 pigs weaned at 16-19 days of age, pigs were weighed individually and allotted to one of five pre-determined weight classes: A (6.9 kg), B (5.7 kg), C (5.2 kg), D (4.7 kg), and E (3.9 kg). Weight classes were based on historical distribution of pig weights in the facility.
Pigs were then allotted to one of two treatments: same weight (SW) or mixed weight (MW) pens. The SW treatment had 22 pigs of the same weight class in each pen (22-A, 22-B, 22-C, 22-D or 22-E pigs/pen), which is more typical of current management practices. The MW treatment had 22 pigs from five different weight classes per pen (4-A, 5-B, 5-C, 4-D, and 4-E pigs/pen).
Instead of budget feeding SW pens according to average initial body weight, all pens (SW and MW) of pigs were fed identical feed budgets. Pigs were individually weighed on day 0 and day 42 post-weaning. Pen weights and feed disappearance data were collected on days 7, 14, and 21 post-weaning. During the first two weeks post-weaning, and for the overall 42-day period, no significant differences were detected between sorting treatments for Average Daily Gain (ADG), (Average Daily Feed Intake (ADFI), or Feed to Gain (F/G), (see Table 1).
Day 0 to 14 Day 0 to 42 Item SW MW SW MW Initial weight, kg 5.3 5.4 5.3 5.4 Final weight, kg 8.4 8.4 23.5 24 ADG, grams 227 227 435 449 ADFI, grams 240 245 567 585 F/G 1.06 1.08 1.3 1.3
Table 1. Effects of same weight (SW) or mixed weight (MW) sorting on nursery pig performance (day 0 to 14 and overall) Akey Trial F3-N01-18 (880 pigs)
Sorting method had no effect on the coefficient of variation (C.V.) for initial weight, final weight or ADG when mixed weight and same weight pens were all fed identical feed budgets. Furthermore, mixing pigs of different body weights within a pen at weaning did not increase ADG or final weight C.V. for the different weight classes of pigs (Table 2).
Initial weight class, kg Item 6.9 5.7 5.2 4.7 3.9 Initial weight C.V., % 9.42 2.98 2.49 3.73 6.51 Final weight C.V., % 11.8 10.9 12.43 12.2 10.04 ADG C.V., % 14.56 14.12 15.93 15.28 12.07
Table 2: Coefficient of variation (C.V) by weight class
Akey Trial F3-NO1-18 (880 pigs)
In Experiment 2, two groups of 880 pigs each were visually sorted in five weight classes and allotted to treatment (SW and MW) as in Experiment 1. However, pens in the SW treatment in this study were budget fed according to body weight. In other words, the heaviest pens were given less of the first prestarter diet, whereas the lightest pens were given more of the first prestarter feed. Pigs in the MW pens all received the average budget of the SW treatment. From day 0 to 45, post-weaning, pigs in the MW group had higher ADG and ADFI compared to the SW group, and were 0.54 kg heavier at the end of the 45-day nursery period. (See Table 3)
Item SW/BF MW/AB Initial weight, kg 4.9 4.9 Final weight, kg 23.5 24.1 ADG, grams 408 422 ADFI, grams 558 572 F/G 1.37 1.36
Table 3: Effects of same weight/budget fed (SW/BF) or mixed weight/average budget (MW/AB) sorting on nursery pig performance Akey Trial F3-NO1-29_36 (1760)
The following conclusions can be drawn:
- Sorting at weaning by mixing pigs of different weights within a pen does not negatively impact growth performance or variation in closeout weight when pigs are fed identical feed budgets rather than budget fed by weight.
- Having pigs of mixed weight within a pen may decrease the amount of time it takes pigs to establish pecking order, ultimately resulting in better gains.
- Gate cutting the majority of the pigs at weaning will result in less handling by farm personnel, decreasing stress for pigs and people.
- Identifying pigs of less than 16 days of age at weaning (at the sow farm) allows nursery personnel to focus on the special needs of these very young pigs.
- Perhaps age rather than body weight alone is a better indicator of the physiological maturity of the digestive system in pigs. If a pig is heavy but young, feeding less of the first prestarter feed may increase the incidence of fallback and sick pigs post-weaning.
- When filling nursery pick out and separate extremely disadvantaged or at-risk pigs (extremely light pigs, sick pigs and pigs of less than 16 days of age) at weaning and applying specialized care (mat and gruel) is still strongly recommended. BP
Ken Palen is a livestock specialist with Kenpal Farm Products in Centralia.
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