Study finds enzymes aid cassava by-product inclusion in poultry feeds

A study by some Brazilian scholars has proven that adding certain enzymes to cassava residues as substitutes for energy-giving ingredients in poultry feeds at a certain age of the birds enhances weight gain, feed conversion ratio, and growth rate.

This, they found out, reduced cost of production marginally in broiler production. Cassava is cheaper than maize, and experts have consistently advocated its use, or its residue, in animal feeds around the world, including Nigeria. The Brazilian researchers have confirmed the efficacy of the substitution.

Uthai Kanto, Associate Professor at Kasetsar University, Thai Tapioca Development Institute, Thailand, had said during an international conference on roots and tubers in China that cassava could replace maize 100 per cent as animal feeds base ingredient to the chagrin of participants.

“We have two types of feeds. One is, we use maize as the base of ingredients and the second is the one we use cassava as the base of ingredients. “If the cassava diet has the balanced ingredients, the performance is not different from maize, but you need to have quality cassava chips for the feeds. The problem in Thailand is that sometimes, the quality of cassava chips is low, with high level of fibers. If cassava has too high fibers, it will deteriorate the quality of chips for animal feeds.

“But if you have high quality cassava chips; if the chips have no more than four per cent of fibres, you will automatically get cassava chips with 70 per cent starch. In that case, cassava as the base of animal feeds ingredients is not different from maize.”

However, what the Brazilian researchers could affirm was supplementing poultry feeds containing cassava by-products with carbohydrase enzymes to help maintain broiler’s feed conversion ratio during the later stage growth. The Brazilians explored the use and influence of dry residue of cassava (DRC) and carbohydrases in the diets of broiler chickens. The study was published in the Journal of Applied Poultry Research​​​.

“The objective of this study was to evaluate the effects of dietary inclusion of DRC supplemented or not with carbohydrases on broilers performance, yield carcass and cuts, blood parameters and meat quality from 22 to 42 d of age,”​ the researchers said.They found that there was a change in the feed conversion ratio (FCR) when carbohydrases and DRC were included in the diets as birds receiving the diet without enzymes saw a linear increase in FCR as more DRC was included in the feed.

Previously, the coproduct has been used without negatively altering performance or carcass quality, they said. It can provide an energy source in non-ruminant diets and replace a percentage of corn.“Dry residue of cassava is a cassava co-product composed of residue of the fibrous material and the starch that was not extracted during root processing,” ​they said. “Dry residue of cassava contains 11% crude fiber, 27% of neutral detergent fiber (NDF), 19.5% of acid detergent fiber (ADF), 60%–70% starch, 3,519 kcal crude energy, and low levels of protein and lipids, in the natural composition,”​ they explained.

Adding exogenous enzymes to DRC could be a way to improve the use of DRC in poultry feeds, the researchers said. Enzymes like carbohydrases, including “xylanase, β-glucanase, β-mannanase, pectinase, and α-galactosidase”​ have been recommended for use with fibrous diets.

“Carbohydrases allow for better nutrient utilization by increasing the digestibility and maximizing the action of the endogenous enzymes on specific substrates,” ​they said. “Carbohydrases can also impact positively intestinal mucosa and reduce undesirable bacteria.”​
During the feeding trial, 950 broiler chicks received one of 10 diets for 21 days, lasting from day 21 to 42 of production, the researchers said. From day 1 to 21 of production the chicks received a pre-experimental corn and soybean meal diet with no DRC or carbohydrases.

Trial diets included DRC at 0, 2.5, 5, 7 or 10% and with or without a supplemental combination of carbohydrase enzymes including xylanase, α-amylase, and ß-glucanase, they said. Diets also contained corn, soybean meal, poultry by-product meal, soybean oil, minerals and vitamins.

Birds were checked for weight gain (WG), feed intake (FI) and feed conversion ratio (FCR) – which were calculated at day 42, they said. Blood samples were gathered on day 42 to check for “cholesterol (COL), triglycerides (TRI), glucose (GLU), total proteins (TP), creatinine (CREA) uric acid (UA), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyl transferase (GGT).”​

A selection of birds on all diets were harvested to assess carcass yield, cuts, meat quality, water retention capacity (WRC) and weight loss by cooking (WLC), the researchers said. The relative weights for liver, gizzard and small intestine were established.Explaining the conclusion of the research, they said, “The DRC can be used in broiler diets up to the level of 10%. “However, it should be supplemented with carbohydrases to maintain FCR in the 22 to 42 day.”​