Glycerides of butyric acid for pig health

Butyric acid is a natural substance present in the gastrointestinal tract (GIT) of swine, where it is produced by microbial fermentation in the large intestine. Numerous studies have demonstrated the positive effect of butyrate on animal performance. Butyric acid not only provides energy to epithelial cells, but it is also involved in processes such as cell differentiation, gut tissue development, gene expression, immune modulation, diarrhoea and enteric pathogen control. It is therefore often chosen as a feed additive for piglets.

Unfortunately, the incredibly bad smell of butyric acid makes it difficult to apply this acid in practice. As a solution, feed additive producers came up with salts of butyric acid. These salts, like sodium- and calcium butyrate, are converted into butyric acid in the acidic environment of the stomach and consequently will be rapidly absorbed. The salts are fat coated in order to release the butyrate further down the intestines with the help of lipase. Due to this coating, the relative amount of butyric acid is low in the product. Another option is to esterify butyric acid to a glycerol molecule, either to form alpha-monobutyrin or tributyrin.

Glycerides of butyric acid

Butyrate glycerides consist of butyric acid molecule(s) attached to a glycerol backbone (Figure 1). An alpha-monobutyrin is formed when the butyric acid molecule is attached to the first (alpha) position of the glycerol molecule. Alpha-monobutyrin is known for its antibacterial effects against Gram-negative bacteria and it is shown that these effects are stronger compared to butyric acid itself. In order to deliver relatively high levels of butyric acid in the intestinal tract, a triglyceride of butyric acid can be used. This molecule consists of glycerol and three butyric acid molecules. Alpha-monobutyrin will reach the small intestine because of its strong covalent bond between the glycerol and butyric acid molecule which furthermore makes the molecules pH independent. Butyrate from tributyrin is liberated from glycerol through the action of lipase in the small intestine. Butyric acid is therefore protected from absorption in the upper GIT and will target the lower GIT.

Figure 1 – Schematic overview of an α-monoglyceride and triglyceride.

The beneficial effect of adding tributyrin has been reported in literature. A trial investigated the effect of tributyrin on growth, intestinal digestive function and intestinal barrier function in intrauterine growth-restricted (IUGR) piglets. IUGR piglets have lower neonatal survival, postnatal growth and immunity. Supplementation with tributyrin has shown to significantly improve body weight compared to IUGR piglets, which did not receive tributyrin. Also intestinal villi were healthier and villi surfaces were larger, resulting in proper nutrient absorption and increased growth.

In scientific literature it has been clearly described that alpha-monoglycerides of fatty acids have stronger anti-bacterial effects than its corresponding fatty acid. Framelco believes that a combination of alpha-monobutyrin and tributyrin will help to maintain gut health, intestinal integrity and microbial control, especially in young animals during times of high bacterial challenge. The antibacterial effect of alpha-monobutyrin helps to control the intestinal microflora, whereas the butyric acid released from tributyrin will provide extra energy for gut development resulting in a better intestinal integrity, immune status and an improved nutrient absorption. For this reason, FRA Butyrin Hybrid Dry, a combination of alpha-monobutyrin and tributyrin was developed.

Weaned piglet trial

A weaned piglet performance trial was conducted at a commercial farm in Denmark to test the effect of the product compared to a negative control group. In total 180 weaned piglets of 26-28 days of age were divided into 2 groups. Piglets were housed in 18 pens to have 9 repetitions of 10 piglets in each pen with an average starting body weight of 6.59kg. In each pen 5 gilts and 5 barrows were placed. All animals received the same basal diets (Feed I & Feed II). The treatment group received mono- and triglycerides of butyric acid at 3kg/ton on top of Feed I for the first 3 weeks and 1.5kg/ton Feed II for the last three weeks of the trial.

Body weight (BW) of all piglets was measured individually by a mobile scale at the start of the trial, at feed transition from feed I to feed II and at the end of the trial. Feed intake was measured every week for each pen. Diarrhoea incidence was recorded twice a week during the whole trial period. Results of the entire trial are presented in Table 1.

A comparison between the control group and treatment group was made for the overall period of 6 weeks. Average daily weight gain of piglets receiving the product increased with 3.7% compared to the control group, resulting in a higher final body weight. Moreover, FCR was improved with 9.5 points (P=0.023). The piglets tended to eat less which could be the result of the energy provided by tributyrin and an improved nutrient absorption because of a better gut development. There was low pathogenic pressure at the farm, but the piglets did suffer from some weaning diarrhoea. There was slightly less diarrhoea in the treatment group during the first 3 weeks after weaning (control diarrhoea score: 1.278, treatment diarrhoea score: 1.167). In the last 3 weeks of the experiment there was no difference in diarrhoea. It is expected that FRA Butyrin Hybrid Dry, including alpha-monobutyrin, would result in an extra beneficial effect when there is higher pathogenic pressure on farm. During this trial in each group one piglet died, the cause of death was unknown.

Feed intake and final body weight six weeks after weaning were calculated for 1,000 piglets to make a clear economical comparison. For each euro invested in the product, a return of € 10.90 was obtained as a result of improved growth and lower FCR. In conclusion, glycerides of butyric acid are a great source of butyrate and improve weaned piglet performances by providing energy and an extra antibacterial agent.

References available upon request

Author: Ellen Damen