High-quality Post-weaning Diet is Critical to Piglet's Transition to Grain-based Diet

Table of Contents

1. Introduction
2. Threonine
3. What is mucin?
4. Arginine and Proline
5. What is a villus?
6. Source

Introduction

This article first appeared in Better Pork, January 2001.

On October 27, 2000, the Canadian Pork Council, in concert with Agriculture and Agri-Food Canada's Dairy and Swine Research and Development Centre in Lennoxville, hosted a swine production research day in Montreal. Nosing around Pig Science brought together a host of researchers from across Canada, covering a wide range of topics. This article will focus on just one of the presentations made during the day-long event.

The goal in feeding weaned pigs is to meet their nutritional requirements for performance and health, while minimizing the post-weaning check, and ultimately to do so economically. According to Dr. Ron Ball, professor and Alberta Pork Producer's Chair in Swine Nutrition at the University of Alberta, the limiting factor in early weaning is intestinal development.

Early-weaned piglets are at a disadvantage because their digestive systems are not adequately developed to handle the digestion and absorption of a typical weaning diet based on grains and vegetable proteins. The digestive enzymes that break down sugars, starch and protein take a considerable amount of time to reach adult levels and can be extremely variable between piglets. As a result, it is common for piglets at this stage to experience a growth lag.

The consumption of nutrients from sources other than milk at this early stage results in an increase in unabsorbed dietary components in the digestive tract, which are used as fuel by particular organisms. What results is a change in the gut microflora, a temporary disturbance in the digestive tract, followed by scouring and a decrease in digestive enzymes. This can result in damage to the gut lining, which increases the absorption of soluble nutrients from the gut and further complicates the problem. As Dr. Ball firmly states, "intestinal development depends on nutrient intake".

Dr. Ball's research has shown that a high-quality post-weaning diet is critical to help the piglet make the transition from highly digestible sow's milk to less-digestible grain-based diets. In order to maximize growth, weaned pigs are currently being fed highly digestible and very expensive diets containing milk and plasma proteins. A diet that would reduce the adaptation time of the pig to the post-weaning diet would be beneficial to both the pig and the producer. A well-developed digestive system during weaning could reduce health and growth problems for the pig, while the producer benefits from lower veterinary bills and lower overall feed costs.

Dr. Ball's research is geared to finding dietary ways of stimulating the development of the digestive tract to shorten the length of time when the high-cost diets are needed. Specifically, his research has focussed on the role of specific amino acids in the process of development and maturation of the small intestine post-weaning. Here are some of the results that have been reported to date.

Threonine

Threonine is an essential amino acid for pigs and the third limiting amino acid in typical corn-soybean meal diets. Dr. Ball's research has shown that the gut uses 55% of threonine intake, indicating it is critical for gut growth, development and function. According to the experimental results, threonine deficiency showed the greatest impact on intestinal mucins (see: What is mucin?). Threonine-deficient diets had an impact on quantity, type and location of mucin in the piglet intestine. During the experiment, every piglet fed the threonine-deficient diet experienced diarrhea, however there was no evidence of bacterial infection. These results suggest that deficiency of threonine could be a factor in poor digestion and digestive upsets after weaning.

What is mucin?

Mucin is mucous that lines the interior surface of the digestive system. In order to maintain normal function in the intestine, mucin:

• prevents digestion of the intestinal wall by digestive enzymes
• prevents water loss through the intestinal wall
• prevents bacteria from adhering to the intestinal cells
• prevents toxins from being absorbed into the body

Arginine and Proline

Dr. Ball and his colleagues have recently proven that arginine and proline are co-essential amino acids in the piglet's diet. Their research determined that the complement of enzymes necessary to manufacture these amino acids is only present in the gut of the piglet, and not in any other organ. With this data, they concluded that piglets require a "fully and normally functional gut" to produce arginine and proline. Results have also shown that the actual metabolic requirement for arginine is at least four times the current National Research Council estimate. Therefore, if the piglet is not consuming adequate amounts of arginine and proline, or adequate amounts of the precursor amino acids from which they are produced, then arginine and proline could become limiting factors for overall growth, as well as intestinal growth and normal metabolism.

Armed with these results, a follow-up experiment was carried out to assess the potential for supplementing commercially available early-wean diets with certain amino acids. The results showed that arginine and glutamate supplementation prevented reduction in villus height (see: What is a villus?) in the small intestine, compared to control pigs. Based on this information, they concluded that glutamate and arginine supplementation could enhance intestinal development of the early-weaned piglet.

What is a villus?

The surface of the small intestine is covered with fine projections called villi (plural) that increase the surface area and absorptive capacity of the gut. The height of the villi is used as a measure of absorptive capacity. On the villi themselves, there are further small projections called microvilli.

Dr. Ball suggests that, in the past, research on gut metabolism has been focused on digestibility of feed ingredients. Meanwhile the gut itself obviously has a major impact on amino acid requirements, suggesting that we need to identify amino acids that are specifically metabolized in the gut. Dr. Ball believes that understanding how the gut of the pig affects the availability of amino acids for growth of the gut, versus that of the rest of the body, will lead to improved early-wean diets and additional help for pigs recovering from gut stress and intestinal disease.

Source

Ball, R.O. 2000. Amino acid requirements of piglets: Implications for early weaning. Proceedings of Nosing around Pig Science - Swine Production Research Day, October 27, 2000.