Lactose has a positive effect on growth performance of piglets in the late weaning period

Lactose is a major ingredient in piglet diet formulations, and even the cheapest piglet diet contains lactose. The reason is simple because lactose growth requires lactose. However, the exact function and mode of action of this important ingredient have not been widely recognized, which limits the rational use of this nutrient to increase feed intake in the post-weaning diet of piglets. This article focuses on the importance of lactose and how best to use lactose in piglets.

Studies have shown that lactose does have a positive effect on the growth performance of piglets in the late weaning period. The most common sources of lactose in these early studies were mainly skimmed milk (50% lactose) and whey powder (70% lactose). Of course, other dairy products may be cheaper now, and the same effect can be achieved with lactose, including crystalline lactose, deproteinized whey, milk chocolate products, cheese powder, and whey protein concentrate.

It has long been known that piglets under 8-10 weeks of age cannot effectively utilize starch. Although starch digestive enzymes can be rapidly caused by diet. However, weaning stress, together with low feed intake, prolongs the developmental maturation of the digestive system. For this reason, monosaccharides (such as lactose) and cooked grains are generally easier to digest than coarse starch. Therefore, it is widely accepted that digestible carbohydrates are more beneficial to the growth and development of piglets before the piglet's digestive system fails to fully digest and absorb the crude starch. In diets with cereals and vegetables as the main source of protein, appropriate supplementation of some dairy products such as whey powder and skim milk powder can improve the growth performance of piglets. In daily diets (corn, soybean meal, and husked oats), adding 10-20% whey powder can increase pig growth by at least 15% at 3 weeks after weaning. Other dairy products can also effectively improve the growth performance of post-weaning piglets, but they are usually more expensive. Initially, the efficacy of dairy products was mainly to increase the palatability of the feed and to increase the digestibility of the protein. However, it has been proven since then that the components of lactose and whey protein can increase feed intake and weight gain in piglets 1 week after weaning. In these trials, supplementation with lactose in diets lacking whey powder restored piglet growth performance, while supplementation with whey protein did not improve growth performance. (See Table 1)

It should be said that the addition of highly digestible proteins or crystalline amino acids to whey-free diets is essential for stimulating the positive effects of lactose. In a similar study (Mahan, 1992), piglets after two weeks of weaning will interact with more supplemental proteins, a sign of a rapidly maturing digestive system, while increasing the density of highly digestible proteins. demand.

Lactose specification

At present, there have been some experiments to determine the level of lactose concentration in the diet to maximize the growth performance of weaned piglets. The results of these tests indicate that piglets require high concentrations of lactose immediately after weaning, which can then rapidly reduce lactose concentrations, and that when piglets weigh more than 10-12 kg, they do not benefit from supplemented lactose.

Although the amount of lactose reaction varies, the demand for lactose in piglets is similar in most trial reports due to factors such as dietary composition, genetic characteristics, environmental and hygienic conditions. Therefore, the recommended recommendations for lactose in the diet are shown in Table 2.

Immunoglobulin

The addition of immunoglobulin (from egg antibodies or animal plasma) to feed may reduce the need for lactose because it increases the feed intake of weaned piglets. For example, within 1 week after weaning, 6.75% of plasma protein in the diet requires an additional 15% lactose to achieve optimal growth performance. Conversely, the use of soy protein concentrate instead of plasma protein requires 30 to 45% lactose in the diet to achieve optimal growth performance. From this result, when the feed intake is high, the dietary demand for lactose is relatively low, perhaps because feed intake is closely related to the degree of development of the digestive system.

Lactose equivalent

Early studies have shown that starch and lactose are more prone to lactose for weaned pigs, but they can also use other forms of monosaccharides. Monosaccharides such as glucose, fructose and maltose, and oligosaccharides such as sucrose and maltodextrin can achieve the same effect as lactose in supporting the growth performance of weaned piglets. The term "lactose equivalent" is proposed to more appropriately express the dietary norms of monosaccharides, such as the piglets themselves do not have the need for lactose. See Table 3 for the value of lactose in several different sources of monosaccharide instead of lactose. However, the use of other different forms of monosaccharides to replace lactose in pelleted feeds may present some new problems. For example, sucrose may increase the hardness of the pelleted feed because sucrose is easily "burned" in the Maillard reaction during granulation. In addition, glucose and other reducing sugars can destroy amino acids during the granulation process. For these reasons, it is recommended to reduce the granulation temperature or even cold granulation in a diet rich in reducing sugars.

Monosaccharides also vary greatly in sweetness. Therefore, changes in adaptability to palatability need to be considered when using lactose substitutes. The preference of piglets for monosaccharides is as follows:

Sucrose > fructose > maltose = lactose > glucose > galactose

It is well known that piglets with high concentrations of monosaccharides are prone to secretory diarrhea. For example, by varying the total amount of sugar (sucrose and starch syrup dry powder), the dietary osmotic pressure can be controlled between 250 and 700 mOsm/kg. Piglets absorb water and carbohydrates from the small intestine, increase osmotic pressure, and minimize the possibility of diarrhea, similar to electrolyte balance. Studies have shown that maltodextrin can even increase the absorption of intestinal water, while glucose promotes intestinal secretion. This suggests that oligosaccharides are more effective than monosaccharides for the prevention of secretory diarrhea.