Small-weight piglets require special treatment if they are to catch up with normal littermates. Post weaning, this is achieved by using the right feed. Not only must the feed match the special needs of underweight pigs, but also its management must meet the reduced appetite for dry feed.

Some producers take the approach that using the most expensive feed or feed ingredients will solve the problem. Unfortunately, this does not work as often as one might hope. Instead, a careful study of the pig production system is needed before a small-weight piglet feed is designed or selected. This, together with “special” management techniques should ultimately produce healthy, economically viable pigs.

Increase in light piglets

A few years ago, a number such as 2% small-weight piglets at weaning was the norm and little was done to address this issue; it was considered and accepted as minimal natural variation. The advent of super hyper-prolific sows weaning up to 35 piglets per year has brought this issue to the highlight, which is already a problem in Europe, though the U.S. is catching up quickly. Now, up to 10% underweight piglets is considered unavoidable if large litters are the ultimate goal. However, these light piglets cannot cope well if fed the same diets given to the rest of the pigs. In the past, the first feed post-weaning was fed for a bit longer to the small pigs, but this never worked very well. Today, a new trend is emerging in designing and using “special feeds” for these “special pigs,” which are not runts or sick pigs but otherwise healthy, albeit very light, pigs.

The challenges with these pigs are threefold. First, their feed intake is extremely low and as such, their diets must be very dense in nutrients and other functional components. Second, their digestive systems are even more immature compared to the rest of the piglets and so, very digestible ingredients are needed to make up their feeds. Third, their health, and especially their gut health, is very fragile and it needs protection and support.

Feed intake

Traditionally, feed intake was enhanced by the addition of "tasty" ingredients and additives. These included dairy products, such as sweet whey, and of course, artificial flavors and aromas. Although such approaches are still valid, more effort is needed to entice smaller pigs to the feed trough. One such approach is through the feed form. A mash (meal) type of diet appears to be working best, especially if it is rather granular in form. This can be achieved by using crumbled pellets, a mix of meal and crumbles, or even a blend of meal and small pellets. When it comes to pellets, durability is not as important as hardness. Small piglets have trouble chewing hard pellets, so a softer pellet is very important in stimulating feed intake. More “advanced” approaches call for semi-moist feed to be used for the first couple or so days post-weaning, but this now belongs more to feed management rather than feed manufacturing, although it is a feed manufacturing challenge itself.

Digestibility

It has been known for a long time now that nutrient digestibility positively affects feed intake. In young, immature pigs, especially those with low feed intake, every mouthful of feed must count. Thus, ingredients with the highest digestibility are needed in such “special” formulas. These ingredients include the best quality sweet whey, low-temperature fish meal, cooked cereals (especially rice), coconut oil (in preference to other vegetable oils), and refined dairy and vegetable proteins with very low levels of anti-nutritional factors (such as pea protein, wheat gluten, soy protein isolate, whey protein concentrate, casein, etc.). Digestibility is also increased by thermal processing, such as pelleting and extrusion. Although piglet feeds are usually pelleted, some manufacturers have started appreciating the advantages of extrusion, while high-dairy formulas pose their own challenges in being extruded. Finally, in lower quality and lower cost formulas, digestibility can be increased by the use of certain enzymes, especially when the diets are based on wheat, barley and other such cereals that are high in non-starch polysaccharides.

Gut health

If piglets are attracted to the feed trough right after weaning and they start eating at least 50-100 grams per day of highly digestible feed in the first two to three days, then few gastrointestinal problems are to be expected. However, even “normal” pigs often abstain from eating anything at all for up to seven days post-weaning (the usual runts and fall-backs that end up in hospital pens). So, it is to be expected that lighter piglets will face at least similar problems. Lack of nutrient intake for as few as 24 hours causes gastrointestinal damage, which becomes more severe as fasting continues.

This damage reduces the secretive (enzymes) and absorptive (nutrients) capacity of the animal. In addition, it induces local (intestinal) inflammation and loosens the junctions between enteric epithelial cells. Under these conditions, opportunistic pathogenic bacteria like Escherichia coli are able to colonize and proliferate due to weakness of the local immune system. Finally, any feed that is subsequently ingested is digested very poorly, thus providing further “fuel” to the growth of undesirable bacteria. In addition, anti-nutritional factors (for example, from soybeans) and toxins (for example, from pathogenic bacteria) penetrate the epithelial barrier through the damaged joints and enter the blood circulation causing systemic damage. The end result: diarrheas, unthriftiness, growth depression, diseases and even death.

It would appear that this must be the most important issue in feeding small piglets. However, it is only because the two issues described above are ignored due to a false notion of economy. Thus, we end up providing other means of protecting and supporting gut health with more or less the same economic result. This is done through two “routes.” First, water soluble medication and other additives like organic acids can provide an early protection even when piglets don’t eat, but do drink water. Second, in the feed, there are two schools of thought on how to address the overall health challenge. One is preventive, the other is supportive. In the prevention camp, additives such as antibiotics, zinc oxide, copper sulfate, organic acids and essential oils belong. In the supportive camp we have additives such as functional fibers, direct microbials, animal plasma and egg antibodies (both sources of immunoglobulins).

Of course, it is quite possible to use both approaches: kill the bad bacteria and feed the good ones. This balance, however, is a delicate one, and quite often overdosage of a good additive can bring the opposite result. This is one major cause of failure for many commercial specialty piglet feeds.

Complications

It appears simple enough to put together a high quality diet by using the most expensive ingredients; but, this is rather deceptive. A few examples will illustrate the underlying complications. For example, fiber is reducing feed intake (bulkiness) and nutrient digestibility (less access to enzymes). But, on the other hand, special types of fiber enhance the proliferation of beneficial bacteria. These, in turn, exclude pathogenic ones to the benefit of the host (animal), while other types of fiber absorb water and reduce the incidence of “soft feces.”

Another example is pelleting, which improves feed intake (compact) and cooked digestibility, but it also promotes gastrointestinal motility (soft feces) and increased digesta liquidity (scours). Finally, when it comes to additives, some organic acids can actually harm certain beneficial bacteria, which is counter-productive especially when such bacteria are being added in the feed, like probiotics.

So, in essence, just piling up all available ingredients and additives simply does not work. Instead, a selective approach depending on end goals is required ensuring a good accord between ingredients, additives and the animal.

Feed management

Placing any feed in a normal feed trough and expecting piglets previously nourished through natural milk to feed themselves rarely works even in normal (heavier) pigs. Although the above approach is labor efficient, any savings in labor are usually spent many times over in additives, medications and expensive feeds; not to mention the profit loss due to unexpressed genetic potential for efficient early growth. Thus, a bit of “tender loving care” in the first two or three days post-weaning can bring about huge benefits in animal performance and overall profitability. The management practices that need to be discussed with the labor force include the following:

1. Feeding little and often, keeping the feed fresh and clean in the troughs.
2. Keeping the bags outside the nursery room to maintain feed aroma.
3. Gruel feeding or feeding a semi-moist feed either manually or by using special feeders.
4. Liquid feeding, implemented on a large scale or done manually in small round pans.
5. Mat feeding, perhaps the most effective way to feed pigs – but wastage can be an issue.
6. Using top-dress appetizers, such as pure sugar or whey, or commercial products.

Parting thoughts

If they are to survive and ultimately thrive, these “special” pigs require both feed that matches their unique needs as well as special management. Although both of these require additional time and energy, most will find the economic return to be well worth it.