Optimizing Poultry Feed with Rice DDGS: Balancing Performance and Cost

Dr Subhasish Ray, M.V.Sc, Animal Nutrition

Consultant Animal Nutritionist, Bhubaneswar, Odisha

In current economic scenario of India poultry sector is contributing 1% to national GDP and 14% to entire GDP by livestock sector. As per last livestock census data of 2019 total poultry population of our country being 851.8 million out of which 63.13 % is under organized commercial sector and rest are under backyard poultry sector (DAHD, 2019). As India has poised to become the most populated country in world, it has become really a tough job to balance the food demand and supply of the nation. Poultry industry has proven to be an efficient asset to balance this unavoidable gap. According to Expert Market Research, the India poultry market, currently valued at USD $28.18 billion, is expected to grow at a CAGR of 8.1% in the forecast period of 2024-2032 to reach a value of approximately USD $44.97 billion by 2032. During the 2022-23, India exported poultry and poultry products to 64 countries, generating revenue of USD $134 million.

The India poultry feed market size reached a value of approximately USD 20566.9 million in 2023. The market is further expected to grow at a CAGR of 7.29%. Price fluctuation of the two major ingredients of poultry feed i.e. corn and soya is a constant cause of worry to poultry entrepreneurs and feed formulators. Reduced production of Soya DOC has impacted in increased price which in turn opens door for use of various not commonly used feed ingredients in poultry feed like corn gluten, corn DDGS (Distillers’ Dried Grains with Solubles), rice DDGS, larval meal, different oil cakes etc.

Rice distillers dried grains with solubles (RDDGS) offer a cost-effective and sustainable protein and energy source for poultry feed, but their use comes with challenges like variable quality and potential toxin content. This article explores the potential of RDDGS in broiler and layer feed formulations.

Steps involved in DDGS preparation

DDGS are the co-products of ethanol industry produced by dry milling. Starch rich grains like corn, wheat, shorgum, bajra and rice can be used for ethanol production. Ethanol (C₂H₆O) is a simple liquid alcohol formed from fermentation of sugars in their natural presence or being derived from starch rich grains or lingo-cellulosic feedstocks. Majorly 3 sources are used i) Feed stocks with substantial amount of readily fermentable sugars, ii) Starches and frunctans iii) Ligno-cellulosic biomass. Corn and rice are the most commonly used starch rich feed stocks used for Ethanol production either by wet milling or dry grinding.

Nutritional Parameters of Rice DDGS

Nutritional composition of any DDGS material varies a lot basically due to variation in the raw material used in Ethanol production and the processing variations in plant. RDDGS is rich in Non Starch Polysaccharides (NSPs) and low in starch compared to the parent raw material i.e. rice. As the most abundant nutrient in rice i.e. starch undergoes complete fermentation in the process, all other nutrients present in RDDGS become many folded or concentrated. In general nutrient composition become three to four times as compared to parent raw material.

1. Crude Protein: A good quality RDDGS should contain 44% crude protein (CP). However CP content may vary from 39% to 47%.
2. Crude Fibre: Crude fibre content may range from 1.23% to 5.33% with 53% co-efficient of variation (CV).
3. Ether Extract: Ether extract content in RDDGS may vary from 3.19% to 7.67%. Moisture content varies between 12% to 16%.
4. Energy: Depending upon the proximate composition the Metabolizable Energy level of RDDGS may fluctuate within 2200Kcal/Kg and 2400Kcal/Kg.
5. Amino Acids: RDDGS has comparatively lower Lysine (0.64% to 1.23%) than Soya DOC (2.99% to 3.22%). Methionine content is in reverse trend i.e. higher in RDDGS (2.0% to 2.8%) than Soya DOC (1.21% to 1.30%). Digestibility of Lysine in RDDGS is quite lower i.e. 65% as compared to Lysine in Soya DOC i.e. 89%. Of course all other Amino Acids also vary in digestibility as compared to Soya DOC and hence these variation need to be taken care of accurately while formulating a ration. During the process of Etahnol production there is reaction between carbohydrate and protein under heat (Miallard Reaction) which reduces the digestibility of protein more specifically Amino Acids.

Minerals: There may be presence of higher bioavailable Phosphorus in RDDGS which needs to be quantified by chemical analysis. Also the total Sulphur content needs to be ascertained as there is addition of Sulphuric Acid in the process of Ethanol production to keep the pH in range. Sulfur levels in poultry greater than 0.6% can produce wet litter problems, while 1.20% sulfur resulted in depressed growth.  RDDGS from different producers vary greatly in nutritional contents mainly due to reasons like source grain variability, temperature variation in liquification, drying process variation and uneven mixing of condensed solubles and wet distillery grain soluble. Generally it has been observed that the sun dried RDDGS tends to better in quality as compared to plant dried material. Yeast by products which remain intact in case of sun drying process, positively influence the gut health when used in poultry diet.

Physical and Chemical characteristics of RDDGS

In addition to its nutritional content, the physical and chemical properties of RDDGS are also important factors to consider when using it in poultry feed. Following are some of the important parameters

1. Color of a good quality RDDGS should be light brown (like fresh de-oiled rice bran). A darker color indicates high heat processing in ethanol making process.
2. Fresh RDDGS smells sweet and fermented whereas charred and smoky smell is indicator of poor quality or over heated material (Cromwell et al., 1993).
3. Particle size of good quality RDDGS should be uniform in distribution and should allow easy and good mixing with other raw materials used in feed manufacturing.
4. A fresh and well processed RDDGS should be granual in texture with adequate flowability. Flowability of any granual materials involve measuring of four different physical properties like angle of repose, compressibility, angle of spatula and co-efficient of uniformity (Ronestrater et al., 2006).
5. Moisture content is the major deciding factor for storage stability of RDDGS. Maximum moisture content should be within 12% beyond which there is high chance of more Mycotoxin and rancidity development.
6. Maximum storage period of any RDDGS should be decided basing upon initial moisture and Mycotoxin content, ether extract percentage, atmospheric temperature and humidity etc.
7. Ideal pH of good quality RDDGS varies from 3.6 to 5.0 with an average value of 4.1. Lower the pH better is the efficacy to reduce bacterial contamination (Tangendjaja et al., 2007).
8. Among all the risk factors associated with RDDGS Mycotoxins comes in top of the list. As all the starch undergoes fermention in Ethanol production hence Mycotoxins content in RDDGS also becomes 3 to 4 folds as compared to parent raw material i.e. rice. Major toxins include Aflatoxin, Ochratoxin, T2 and Fumonisin. Maximum permissible limit for Aflatoxin should be within 20ppb, of course finding an ideal RDDGS with minimum level of mycotoxin is always a challenge for feed manufacturers.

Inclusion in Broiler and Layer Diet

Contradictory findings have been reported by various researchers for inclusion of RDDGS in broiler diet. Thein et al. (2020) and Khose et al. (2021) have observed no negative effect of RDDGS included in broiler diet at 20% and 15% level, respectively. Shirisha et al. (2021) and Talasani et al. (2021) witnessed better performance results of RDDGS in broiler diet at 16% and 20% inclusion levels, respectively. Whereas Dingore et al. (2015) observed negative effect at 15% inclusion level. Basing on the production target, cost and raw material quality the optimum inclusion level of RDDGS has to be designed by the nutritionist by addition of suitable feed additives and the range may vary from 5% to 15%

Increased corn-soya price and decreased egg rate forces producers to for alternative raw materials like RDDGS. Shirisha et al. (2021) conducted a trial to assess optimum level of inclusion of RDDGS in layer diet and found a strong positive response up to 15% inclusion with addition of exogenous cock-tail enzyme. Gupta et al. (2016) have reported positive response of RDDGS addition in Layer diet up to 10% level. Age of the birds, production status, stress level, raw material quality along with  addition of suitable feed additives are the key factors to judge the optimum and maximum level of inclusion RDDGS in layer diet. The range of addition may vary within 3% to 10%.

Optimization of feed cost by RDDGS inclusion:

As a viable energy and protein alternative, the use of good quality RDDGS can significantly reduce poultry feed cost. Soya DOC has more Lysine and low Methionine whereas RDDGS contains low Lysine and more Methionine. So, both protein sources are complementary to each other when used judiciously. RDDGS is INR 15 to INR 20 cheaper than Soya DOC per Kg. Considering per unit nutrient costing RDDGS can also be used as a suitable alternative feed ingredient for significant reduction in feed cost without compromising quality. By using RDDGS judiciously and scientifically feed costing can be reduced by INR 300 to INR 600 per MT in layer diet and INR 500 to INR 1000 in broiler diet.

Precautions while formulating feed with RDDGS

1. Analysis: Detail wet-analysis of the raw material to be done to get exact values of parameters like Moisture, Crude Protein, Ether Extraxt, Crude Fibre, Amino Acid etc and those data need to be incorporated minutely in formulation.
2. Quality: Physical qualities like color, smell, texture etc. and chemical parameters like mycotoxin level, pH etc. need to checked properly before incorporating into diet. Storage period of RDDGS should be decided upon initial moisture and toxin level.
3. Maximum inclusion level: Maximum inclusion level of RDDGS has to be finalized by the nutritionist basing on various interacting factors like genetics of birds, climatic condition, other raw material pricing, daily feed intake, target production level, stress level, prevalence of any disease etc.
4. Toxin Binder: A modern generation good quality toxin binder should be chosen by nutritionist to counter probable toxic effects. As it becomes difficult to assess the quality of toxin binders as such, it is always advised to use Toxin Binder of reputed manufacturers.
5. Liver health: Sufficient Biotin, Choline and other methyl donor should be there in diet in order to support Liver health to the fullest. A well maintained Liver is always efficient to utilize all the nutrients present in feed efficiently which gets reflected in production parameters.
6. Immunity status of birds: Adequate Biosecurity as well as Vaccination schedule should be maintained in farm in order to keep the optimum immunity level in birds. It always becomes risky to use higher level of non-conventional feedstuffs in immune-compromised birds.

Summary

Rice DDGS being a co-product of Ethanol industry is not a new or noble feed ingredient in poultry industry. Variation in process of Ethanol production impacts widely on the nutritional parameters of RDGS. Selection of good quality RDDGS is a blend of art and science which need to be developed by experience. Nutritional variability and higher Mycotoxin content of RDDGS needs to be taken care of accurately while formulating poultry feed. Still it is not conclusive to dictate exact maximum level of inclusion, which needs to be decided by nutritionist considering all associated factors. Judicious and scientific use of RDDGS in poultry diet has huge economic beneficial effect without compromising the performance of flock. There is no alternative to extensive research on use of RDDGS in poultry diet efficiently.