Fermented wheat, enzyme use may boost piglet feed digestibility

A team of researchers from the University of Manitoba in Canada examined the use of diets including fermented wheat for weaned pigs. The researchers published their work in the journal Animal Feed Science and Technology​​​.

“This study was performed 1) to investigate the effects of including fermented wheat in the nursery diet on nutrient and energy digestibility as well as microbial metabolites, 2) to compare the effects of Hetero- and Homo-fermented wheat containing diets on nutrient digestibility, and 3) to examine the effects of enzyme complex supplementation during fermentation,”​ the researchers said.

Piglets getting the trial diets demonstrated increased digestibility for several nutrients and amino acids (AA), the researchers said.

“Adding an enzyme complex as a wheat fermentation additive enhances subsequent nutrient digestibility (e.g., minerals and AA) for weaned pigs when the wheat is included in the nursery diet,” ​they said. “However, although fermented wheat diets had a lower pH assuming the presence of lactic acid, they did not alter the pH in the ileum or feces.”​

Why Lactobacillus fermented wheat?​

Using fermented cereals can help young pigs that have an immature digestive capacity and immune system, said the researchers. Microbial activities during the fermentation process partially degrade some of the anti-nutritional factors and can release some nutrients for use by the animal.

The process may reduce large molecules of starch and protein making them easier to digest and absorb, they said. Some metabolites of fermentation, like lactic acid, have been linked to a reduction in gut pH and pathogen suppression.

Lactobacillus ​plantarum or homofermentative Lactobacillus ​plantarum (Homo) has been used to ferment monosaccharides into lactic acid, which can then generate acetic acid, propionic acid and ethanol, they said. Using Homo as an inoculate can lower pH and reduce bacterial action.

Adding L. buchneri​ or hetero fermentative L. ​buchneri (Hetero) in the fermentation process tends to produce volatile fatty acids and antifungal activities, they said.

However, an examination of the inoculants, either used alone or with enzymes, has only been done in ruminants, said the researchers. “In addition, to the best of our knowledge, no studies have investigated the influence of fermented wheat on ileal digestibility of amino acids (AA) and microbial metabolites in weaned pigs,”​ they added.

It is anticipated that using fermented grains would improve digestion of nutrients and energy in the diet, they said. And diets both fermented and with an added enzyme should see a larger boost to digestibility.

Feeding trial details​

In the feeding trial, 14 weaned piglets were fitted with T-cannula in the distal ileum and then given one of seven diets for a period of nine days, the researchers said. Piglets were rotated to a new diet three times during the trial.

The seven experimental diets included a wheat-based basal diet or negative control (NC) and that diet with 0.5g of an enzyme complex as a positive control (PC), they said. The other diets were a “Homo-inoculated wheat diet, 4) Homo-enzyme complex (0.5 g/kg)-inoculated wheat diet, 5) Hetero-inoculated wheat diet, 6) Hetero-enzyme complex (0.5 g/kg)-inoculated wheat diet, and 7) casein-corn starch-based diet.”​

The casein-corn starch diet was used to estimate the basal endogenous losses for crude protein (CP) and amino acids (AA), they said.

Piglets were given a 5-day adaptation period and then diet, fecal and ileal digesta samples were collected for analysis of volatile fatty acid (VFA), pH and other elements including AA, CP neutral detergent fiber (NDF) calcium (Ca), phosphorus (P), acid detergent fiber (ADF), phytate and non-starch polysaccharides (NSP), they said. “All samples were analyzed for dry matter (DM), organic matter (OM), gross energy (GE), ether extracts (EE), and titanium dioxide,”​ they added.

The coefficient of apparent total tract digestibility (CATTD), coefficient of apparent ileal digestibility (CAID), coefficient of standardized ileal digestibility (CSID) of AA and basal endogenous loss all were calculated, the researchers said.

Results​

Piglets remained healthy, found the feed palatable in all diets and average weight gain was similar, the researchers said. Overall, adding the enzyme to the fermented diets improved the digestibility of minerals and amino acids.

“Feeding a nursery diet comprising fermented wheat increased the nutrient and energy digestibility,” ​they said. “Inoculating wheat with Hetero is more beneficial than inoculating it with Homo in terms of energy and mineral digestibility.”​

The fermented diets were found to have less DM, OM, starch, NSP, NDF and GE than the diets with non-fermented wheat, they said. Fermented diets also had less soluble NSP by about 28%, were lower in pH and AA contents tended to be greater.

“Greater CAID of GE and starch was observed in pigs fed the fermented wheat diets than in those fed the NC diet,​” the researchers said. “Similarly, CATTD of DM, OM, GE, and P were greater in weaned pigs fed fermented wheat diets than in those fed the NC diets.”​

Pigs on the PC diet had improved CAID of starch and total VFA concentration compared to the NC diet, they said. But, the use of an enzyme did not alter the CATTD of nutrients or energy.

“Weaned pigs fed a diet containing Hetero-fermented wheat showed greater CAID of DM, OM, and GE as well as greater CATTD of EE, Ca, and P than those fed a diet containing Homo-fermented wheat,”​ they said. “Further, ileal DE was greater in Hetero-fermented wheat diets than in Homo-fermented wheat diets.”​

However, adding an enzyme complex did not alter the CAID for nutrient or energy but did boost the CAID of EE, Ca and P, they said. The enzyme-supplemented diets had greater CAID and CSID of valine, tyrosine and phenylalanine.

Pigs getting the fermented diets also had greater CAID of methionine, alanine, cysteine, and tyrosine along with improved CSID of methionine, alanine and proline, said the researchers.

Source: Animal Feed Science and Technology​

Title: Nutrient and energy digestibility, and microbial metabolites in weaned pigs fed diets containing Lactobacillus–fermented wheat​

Authors: B. Koo, J. Kim, C. Nyachoti

DOI: doi.org/10.1016/j.anifeedsci.2018.04.007​​