Dr. Atul P. Dhok and Dr. Nitin V. Kurkure
Maharashtra Animal and Fishery Sciences University, Nagpur, 440001
Ph. 9921310135 Email: nitinkurkure@mafsu.in
Introduction
Livestock and poultry rearing is one of the most important activities in the rural areas of the country contributing significantly to the national economy. Presently the Gross Value added (GVA) of the livestock sector contributed to Indian agriculture is increasing steadily with a share of 30.79% in the agriculture and allied sector’s GVA and 5.73% in the country’s total GVA.
The livestock feed contains a substantial amount of cereals and oil seed meals, which directly compete with human consumption. Because there is nearly no more room for agriculture, the availability of feed resources could be one of the biggest obstacles to increasing production in the future. Hence it is imperative to look for alternate feed sources and in developing nations like India, there is a greater need for alternative ingredients, which has a significant impact on the need for feed and raw materials. The increased cost and the limited supply of conventional grains have necessitated focusing research and extension efforts towards the potential utilization of energy and proteins from several grain by-products which are cheaper with high nutritive values. Distillers Dried Grains with Solubles (DDGS) can play a vital role in formulating less expensive diets for dairy animals.
Production process to get DDGS
It is a co-product of ethanol production plants that use corn for manufacturing. During the yeast fermentation in ethanol plants, corn is ground, mixed with water, cooked and the liquefied starch from this process is hydrolyzed and fermented to produce ethanol and CO2. As a result, the non-fermentable components of this process which are rich in essential nutrients such as protein, fat, fiber, vitamins, and minerals are recovered in a highly concentrated form as Distillers Dried Grains with Solubles. They are produced by drying mash over an extended period of time after multiple stages of concentration. These products are made up of initial raw material components that are resistant to fermentation (such as non-starchy carbohydrates, protein, fat, and ash), as well as yeast biomass. Protein, exogenous amino acids, B-group vitamins, biotin, and mineral components, including phosphorus, are all abundant in the dried grains of cereal distillers.
The following two major products are available from this industry
Wet Distillers Grains (WDG) contain primarily unfermented grain residues (protein, fibre, fat and up to 70% moisture). WDG has a shelf life of four to five days. Due to the high water content, WDG transport is usually economically viable within the area nearer to the production facility.
Dried Distillers Grains with Solubles (DDGS) is WDG that has been dried with the concentrated thin stillage to 10-12 percent moisture. DDGS has a long shelf life and may be shipped to any market regardless of its proximity to the production facility. Drying is costly, as it requires further energy input.
The conversion rate of grains to ethanol and distiller’s grains varies with the different types of grains and the process used. One ton of corn produces approximately 378 L of ethanol and 479 kg WDG (70% moisture content), or 309 kg of DDGS (10% moisture content). Also, one ton of wheat produces approximately 372 L of ethanol and 457 kg WDG (70% moisture content), or 295 kg of DDGS (10% moisture content).
Nutritional characteristics of DDGS
The high protein DDGS, resulting from the pre-fermentation fractionation of the corn grain, contains approximately 40% crude protein. The solubles stemming from the fermentation of fractionated corn grain are combined with the corn hulls and sold for use in ruminant feed. Except the majority of the starch, which has been consumed during the fermentation process, it contains all the nutrients from grain in a concentrated form. It has 35% soluble distiller’s grain and 65% distiller’s grain. The DDGS from various sources at different locations of the country contained average protein and fat content of rice DDGS as (45.88 and 4.36) and corn DDGS as (28.50 and 7.36). The presence of dead yeast cells gives the protein better amino acid composition and very good nutritive value. Corn dried distillers grain is rich in phosphorus (0.43–0.83% of dry matter) and sulphur (0.31% to 1.93% of dry matter).
Feeding of DDGS to dairy animals
DDGS can be included in dairy animal diets up to 20 percent without decreasing dry matter intake, milk production, and milk fat. When formulating diets containing DDGS for lactating dairy cows, consideration should be given to the type of forage, forage-to-concentrate ratio, crude fat content of DDGS, and the need for supplemental lysine to achieve optimal performance. Rice DDGS can be effectively used in TMR by lactating dairy cows making it a valuable feed ingredient for use in dairy rations. In the case of ruminants, it is important to note that the distiller’s grain is a feedstuff with high UDP, with beneficial fiber content that does not cause rumen acidosis. DDGS has a positive influence on milk yield and its fat and protein content.
Because of the high content of insoluble fiber, DDGS has a positive influence on digestion and lowers the pH in the digestive system. This results in the reduction of the pathogen population and diminishes the occurrence of diarrhoea in young animals. DDGS is also a good source of protein and energy for lactating cows. In DDGS, the main carrier of energy is fat and neutral detergent fiber (NDF), which constitutes 40–45% of dry matter, has a low content of lignin, and easily ferments in the rumen to produce volatile fatty acids. So, DDGS is a feedstuff that can restrict rumen acidosis. DDGS may be a valuable source of phosphorus in the postpartum period preventing hypo-phosphatemia. It is also rich in sulphur and corn DDGS may contain from 0.31% to 1.93% sulphur in dry matter which may provide sulphur anion-reducing cation-anion balance of feed ration (DCAB). This is desirable for preventing postpartum paralysis in animals.
Future Scope of DDGS in dairy animal feeding
Existing research results suggest the effective use of dry and wet distillers grains in livestock nutrition and especially the inclusion of corn dried distillers grains (DDGS) in feed rations for cows. Reprocessing the by-products of agriculture and food industry is likely an alternative to the traditional nutrition of animals. It is also a good way of utilizing the valuable nutrients that these by-products contain. Corn DDGS is particularly a valuable feed for dairy cows in the postpartum period, when its use prevents postpartum paralysis, as it is a good source of phosphorus and sulphur, diminishes the negative balance of energy due to more fat content and chances of rumen acidosis due to favourable composition fiber fraction NDF. It also improves the feed intake due to yeast content. From the environmental perspective, one of the beneficial effects of DDGS as a component in feed rations is the decrease in methane production. Another may be lowering the costs of feed for animals as it is relatively cheap. Additionally, milk producers are now switching from conventional feed to more nutritionally balanced compound feed, which may favour the use of DDGS in the dairy ration.
Conclusions
Feeding distillery grains to dairy cows is a viable option for dairy farmers to provide supplemental rumen undegradable protein and energy to dairy cows, with equal or improved milk production. When feeding distillery grains to dairy cows, nutritionists and producers must pay close attention to dietary CP and RDP, Phosphorus and Sulphur, and fat concentrations to obtain optimum rumen function, productivity, and nutrient excretion.
Utilizing DDGS in livestock feed offers opportunities but requires careful formulation and quality control due to nutritional variability. Compared to other feeds, DDGS is cheaper but its use poses problems, as it is a changeable composition, which requires technological procedures to standardize it. Attention to factors like rumen unsaturated fatty acid load and DCAD is crucial for ruminants. DDGS’s nutritional benefit enhances its potential as a valuable, sustainable feed ingredient for dairy animals.