Post-weaning feed intake has always been rather low compared to genetic potential for growth in early-weaned pigs. This costly problem is attributed mainly to early weaning at 3 weeks, as opposed to natural weaning at about 8 weeks of age. Under most commercial conditions, weaned pigs invariably experience some degree of appetite depression. This increases production cost and reduces growth performance through the finishing stage, affecting profitability in a negative way. It is not uncommon for pigs to starve for as long as 3 to 5 days after weaning, whereas others may start eating a few minutes after placement in the nursery building.
A low-quality environment and poor health status certainly do not help an already affected appetite.
The reasons for post-weaning anorexia are many and complex. The general consensus is that weaned pigs do not eat because of radical changes in their feeding behavior, and feed form and composition after weaning. Before weaning, the sow was responsible for feeding piglets at frequent intervals, and communal liquid feeding was, thus, the norm for piglets. After weaning, the piglets are faced not only with a stressful physical and social environment, but also with the decision of when and how much to feed themselves. To make things worse, where water was provided before in conjunction with solid matter in sow’s milk, now the weaned pig needs to distinguish between thirst and hunger and also to realize that these needs must be satisfied via separate media — dry feed and water. A low-quality environment and poor health status certainly do not help an already affected appetite.
But why is ensuring a high feed intake during the early post-weaning period so important? Research has repeatedly demonstrated that low feed intakes during the early post-weaning period severely limit future growth potential, increase temperature and management requirements, intensify morbidity and mortality, and reduce turn over of facilities. The following generic rule may be applied to understand this issue:
For every 100 grams of extra feed intake per day during the first week post-weaning, body weight increases by at least 2 kilograms at the end of the fourth week post-weaning.
This has a dramatic effect on overall performance during the growing-finishing period as pigs that barely maintain their weaning weight during the first week may take an extra 10 days to reach market weight compared to pigs that grow at their pre-weaning gain rates (about 200 grams per day) during the same period.
Early-weaned pigs require about 250 grams of dry feed per day during the critical first week post-weaning, to maintain their pre-weaning growth rate. Actual feed intakes, however, rarely exceed 100 grams per day during this period, and this is barely enough to maintain body weight at thermoneutral conditions. Fortunately, progress in nutrition and feeding management has equipped producers with an array of measures to prevent starvation and enhance post-weaning feed intake. All or some of the following are used successfully in profitable operations:
- Management. This may be rather obvious, but it cannot be overemphasized how important hygiene and management are in creating an environment for maximal post-weaning performance. Increased biosecurity, an aggressive farm-specific disease prevention program, improved pig/human flow and continuous staff training are essential parts of a professional nursery site. Well-trained managers are the most valuable and sometimes the hardest-to-find assets.
- Diet digestibility. Feed intake generally increases with improving digestibility of the diet. This is a well-known fact, and it is the main reason why most piglet diets are fortified with cooked cereals, milk proteins, fish meal and simple sugars like lactose and sucrose. Although such diets are more expensive than simple diets (based on maize and soybean), the benefits are tremendous in terms of improved performance and health during the whole grow-out period. Ingredients of poor digestibility pass rather intact along the gastrointestinal tract to the large intestine where they promote bacterial proliferation that invariably leads to diarrhea.
- Specialty ingredients. Antimicrobial agents at growth-promoting levels, zinc oxide and copper sulfate at pharmacological doses, certain organic acids, and in-feed immunoglobulins (from hyper-immunized egg protein or animal plasma) improve post-weaning feed intake and growth. Other highly-digestible protein sources such as fish meal, skim milk and wheat gluten do offer growth promoting advantages as well. An improvement of 10 to 50 percent in growth performance can be easily realized when the proper combination of these ingredients is used. Generally, these ingredients are more efficacious when health, facilities and management are sub-optimal. Improvement in these aspects of production always reduces dependence on such ingredients and reduces feeding cost.
- Balanced budget. Even though high-quality piglet diets are very helpful in promoting growth performance after weaning, their advantages can be easily lost if they are fed for too long or at the wrong amount for each weight class of weaner pigs. A properly designed budget has a higher allowance of the complex diets for light-weight pigs than for heavy-weight pigs. However, a common mistake is to disregard the fact that heavy pigs are accustomed to consuming large quantities of milk and, thus, they tend to take longer than light-weight pigs to adapt to dry diets. Therefore, a small allotment of the first diet should always be budgeted even for the heaviest pigs. This will prevent them for slowing down or even falling back on their growth rates. It will also reduce variability at the upper range of weights.
- Mat-feeding. This is probably the most cost-effective way to increase post-weaning feed intake by spreading a small quantity of feed on floor-mats or on solid floors. It greatly encourages pigs to rut and ingest solid feed as early as the first day post-weaning. A mash provides equal results with pellets, but on mats without a rim, pigs like to roll and push pellets instead of picking them up. Placing the mat near the feeder seems to encourage pigs further to consume more feed from the feeder. Pigs require only 2 to 3 days of floor feeding before they become accustomed to eating from regular feeders. Frequent feeding stimulates pigs to eat more and prevents wastage of uneaten portions. However, based on our own research, feeding more than 3 times daily is not advised because pigs become too fond of mat-feeding. Growth performance comparable to pre-weaning rates can be easily achieved, but wastage can become excessive without proper management of mat-feeding.
- Milk replacers. Nursery pigs will readily consume a warm liquid milk replacer of the proper temperature and composition. Feeding a milk replacer 3 to 4 days can easily double dry matter intake compared to a pelleted starter formula. However, pigs reared solely on a liquid diet may fail to relate to dry feed unless the milk replacer is combined with a high quality starter diet or milk pellets. Good sanitation and frequent feeding are essential to prevent spoilage and attract pigs to eat. Milk replacers are best suited for low-weight and orphan pigs because of cost constrains. An investment in equipment and labor is also required to reap the full benefits of milk replacers.
- Gruel feeding. In farms where pigs are fed dry diets on a regular basis, a warm gruel (50:50) of feed and water (or a liquid milk co-product) can be offered to weaned pigs in special bowl-type feeders during the first 2 to 3 days post-weaning. This practice prevents starvation, and more importantly, dehydration. Unless the gruel is gradually thickened (70:30), some piglets may fail to adapt to dry feed. Precipitation of solid matter in bowls is not problematic as long as the bowls remain filled with water. Field results with this practice are very encouraging.
Learn more: 8 questions to ask when purchasing piglet feeds