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What limits growth in piglets?

Ioannis Mavromichalis
We all know very well that young pigs fail to realise their full potential for growth, at least in the period immediately post-weaning. With this statement, I would like to invite our readers to contribute their thoughts on the reasons or factors that limit post-weaning growth and (or) feed intake. My own thoughts on this very controversial topic are below:

The major drive for growth in post-weaned pigs is believed to be feed intake, or rather more correctly, energy intake, as it has been demonstrated very clearly by Campbell et al. (1975). Under this understanding, it appears the failure to provide nutrient-dense diets is one of the major reasons why growth is depressed in young pigs.

Genetics & Sex
It appears genetics and sex play only a minor role, if any at all, at the post-weaning phase, with a few studies showing gilts having a slightly higher feed intake. Under practical conditions, however, these two aspects are not significant enough to cause marked differences in performance post-weaning.

Immunological stress
This appears to be the most widely-talked issue today, yet it is only lately recognised at least in the proper magnitude of significance for growth and feed intake post-weaning. Under the best commercial conditions, pigs are exposed continuously to a myriad of pathogenic and non-pathogenic micro-organisms. Even though disease may not always prevail, chronic exposure to antigens constantly triggers the immune system and causes sub-clinical disease symptoms that are difficult to identify and quantify. Chronic activation of the immune system reduces appetite, increases muscle protein degradation, reduces muscle protein synthesis, and diverts nutrients to the synthesis of components of the immune system such as acute-phase proteins. The negative effects of chronic activation of the immune system (i.e., sub-clinical disease) in pigs reared under immunological stress are illustrated in the following table.

Management stress
It is now understood that stress affects negatively the immune system depressing feed intake and growth, not only in weaned pigs but also in all other phases of production. Pigs exposed to multiple management stress factors have their growth performance depressed in an 'additive' or cumulative pattern. As a rule of thumb, each stress factors depresses growth by about 10%.

So, in your opinion what else is missing from this list?


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    Dr. Elijah Kiarie

    Sure Dr. Ioannis, in addition to your points, there ought to be a question which most experimental designs fail to answer? Pluske et al. (Murdoch) & other groups have shown repeatedly that the gut integrity is impared upon weaning but failed to show why?. Impared gut means reduced digestive and absorptive capacity, & possibly increased gut associated nutrients demand for repair( Nyachoti et al.;Manitoba). My thinking is that the naivity of the piglet intestinal mucosal immune system (i.e. its failure to differentiate innocuous & harmful microbial & non-microbial antigens) is the culprit. In this context, I believe a successful nutrition program for the nursery is the one which is capable of transitioning the piglet to optimal gut integrity in the shortest time possible.
    Dr. Elijah Kiarie
    Puratone cooporation Niverville, Manitoba, Canada

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    Gregg Bisset

    From a stockperson perspective I think the critical factors in the early growth of weaners happens very early in life. This involves getting the piglets to eat creep very early and get them to consume prior to weaning. There is enough stress at weaning without feed refusal for hours or even a day or more. Even a few stressed piglets can impact on the whole group by their distress behaviours causing stress across the whole group. Stress = immune system being compromised = disease & gastric upsets. Excellent intakes prior to weaning are achieved on our farm by feeding procedures, creep bowl design and weaning 10% of piglets at 21 days and mixing them through the pigs weaned at 28 days as they teach the other pigs who haven't learnt how to eat to eat very quickly. We regularly achieve average of 36 kg weights at 9-10 weeks from weaners weaned at 7-8 kg.

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    Dr Nikolaos Kotrotsios


    I would like to emphasize to the knowledge, ability and willingness of the person in charge of the stock to care fully for their needs. Good husbandry was considered to be synonymous with animal care and also with profitability. First and foremost comes to the need to improve the quantity of animal products available to the human population and next to reduce the price of the animal products. The human view of the animal’s state being that of the study of animal behavior and his experience to the subject, provides the basis of proper supervision and stockmanship, and a major means of improving both the level and efficiency of piglets production.


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    Ioannis Mavromichalis

    Gentlemen, first many thanks for your very insightful contributions! Yes, my list is far from being exhaustive, so I am sure many more good points will be brought up. And, I totally agree with your points.

    I believe, it was Pluske's group that proved post-weaning deterioration of gut integrity is due to loss of substrate and that sufficient feed intake would prevent this. This brings us back to the old topic of how to make pigs eat, and here your comments are correct in that the stockperson taking care of the pigs is THE most important factor.

    Gregg, I recall your numbers were always very good and this was not only because you were using high quality diets. Stockmanship combined with a top quality diet, proper environment, etc, is certainly the key to a successful rearing.

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