Methodology of Quality Improvement of Feed Stuff

Introduction

Demand for livestock products is increasing worldwide, along with population growth, urbanisation, and rising incomes (Alexandratos and Bruinsma, 2012). However, shortage and the increasing cost of good quality feed ingredients of animal feed in most developing countries severely constrain the exploitation of feed for improving their livelihoods, food, and nutrition security. The sources of animal feed are natural pasture, crop residues and agro-industrial by-products. The primary feed resource for livestock in traditional production is crop residues of  low quality, high fibre content, low digestibility. Despite the wealth of ‘research-proven technologies for feed improvement, only a few success stories exist in livestock feeding in smallholder systems in such countries because of the low level of adoption of the ‘promising’ technologies by the farmers.

Financially, feed costs account for up to 70% of the total variable costs of livestock production and may reach 90% in more intensive systems (Makkar, 2016a). Good quality feed improves livestock productivity, resulting in lower age at first calving and shorter inter-calving interval thus increases productive life and profitability (Linde et al., 2002). Proper feeding improves animal immunity (Vighi et al., 2008), health and welfare. It enables higher productivity under a given management regimen (Absalón-Medina et al., 2012) and contributes to environmental sustainability by converting energy and nutrients from land. Feed quality enhancement focus on improving nutritional value, palatability, intake, and digestibility of low-quality feeds like straw, stovers.

Nutrition could be a severe limitation to livestock production, especially when feed resources are inadequate in quality and quantity. Quality is defined as the “Degree to which a set of inherent characteristics fulfils requirements”. This indicates that achieving quality means fulfilling requirements. The requirements may come from customers and, in some cases, from regulatory authorities. The quality of feeds is based on the quality of its constituents. In India, quality control is regulated by a statuary body Bureau of Indian Standards (BIS).

Practical feed quality improvement technologies

1. Improving feed productivity: By introducing higher yielding and higher quality forage species, including legumes like Azolla bio feed and Soilless Hydroponics, greenhouse forage production (Foster et al., 2009).
2. Enhancing feed quality: By Physical, chemical, physicochemical and biological treatment and by Fertilization of crop (Reddy et al., 2003; Haileslassie et al., 2013).
3. Maintaining or conserving feed quality of forage: Storing fresh fodder under anaerobic conditions to preserve the quality with minimal energy and nutrient loss and spoilage is called silage making/ ensiling (Titterton and Bareeba, 2000). Surplus, green fodder such as maize, sorghum, bajra available in the rainy season can be preserved as silage for feeding during the lean season. Silage from cereal fodder contains about 2-4% DCP and 50-63% TDN. Reducing nutrients from green fodder by drying is called haymaking (Klinner and Shepperson, 1975). Good quality legume hay may reduce the cost of production by replacing a certain amount of concentrate in the ration. Sorghum lost its cyanide toxicity during drying and Vit. D content is very high in the hay.
4. Fortifying the nutrient content of the diet: We can supplement the diet with commercially available nutrients like amino acids, mineral supplements, vitamins. Chelating Mineral mixture like Metal specific amino acid complex, Metal Amino acid chelate, Mineral proteinates, Mineral polysaccharide can also be used to increase mineral bioavailability (Hudson et al.,2004). Chelating agents like EDTA are used to improve the bioavailability and absorption of Zn. Bypass nutrients prevent negative energy balance in high yielding animals. Protected proteins are digested more efficiently in the small intestine, so extra protein will be available for milk production and improvement in quality (Selemani and Eik, 2016).

Quality Improvement (Feed evaluation) of poor-quality roughages (PQR)

By Supplementation with

1. NPN sources (urea) and molasses: Rumen microorganisms first break down 100% urea to ammonia, which then serves as a nitrogen source to produce microbial protein, ultimately serving as a protein source for the host ruminant. Molasses used at 5-10% level as a carrier for urea impregnation of poor-quality roughages, as a binder for commercial pelleted feeds, as a sweetener for increasing voluntary intake of compounded feed.
2. Urea molasses liquid or solid supplements (UMMB) (Makkar et al., 2007): At Ludhiana, the Uromol compound was prepared by heating urea and molasses in the ratio of 9:1 (w/w) at 110°C. The block is licked by the animal, ensuring a small progressive and regular intake of urea. Multi nutrient blocks provide the opportunity to utilize any locally available agro-industrial by-products, e.g., brans, pulps, poultry litter (Kayouli et al., 1993).
3. Green fodder (either leguminous or non-leguminous) and Legume straws (like sun hemp, horse gram, cowpea, gram straws) can be supplemented with the PQR.

By Treatment

The main objective of treating a poor-quality roughage (PQR) is to increase its digestibility and voluntary intake.

Physical Treatment

1. Soaking: Soaking of wheat straw increased the DMI and VFAs production but no effect on the digestibility of nutrients. Soaking of paddy straw removes some of the oxalates (an ANF) and may improve the nutritional value of straw and improve Ca retention more importantly.
2. Reducing the particle size of crop residues: It is achieved by chopping/chaffing. Fodders are chopped uniformly into course (1-2 cm) particles with a hand or power-operated chaff cutter. Chopping reduces selective feeding and wastage, increases pellet quality, facilitates mixing with other ration ingredients, easy handling, and storage. In addition, it improves the intake and digestion of feed due to exposure to a relatively larger surface area of roughages for microbial digestion (Hamed and Elimam, 2009).
3. Boiling under high pressure/ Steaming Method: This method has a more significant effect on improving the feeding quality of straw. This breaks the chemical bonds through steaming at high pressure, which increases the digestibility of the final product. D.V. Rangnekar (1982) from BAIF, Ahmedabad, proposed using surplus steam in sugarcane industries to treat bagasse.
4. Pelleting: The ground roughages are pelleted and fed to animals. It improves the consumption of poor-quality roughages. A complete feed is made by pelleting poor quality roughage with 30% concentrates.
5. Irradiation: Improvement of digestibility of wheat straw by X-rays is beneficial due to the breaking of the cellulose and hemicellulose bonds, resulting in the formation of oligosaccharides. Forage lignin resists the X-rays. Upon irradiation, ergosterol, a plant sterol, yields vit. D₃. This method involves high cost.

Chemical Treatment

Chemical treatment aims to increase lignin solubility or decrease the bonds between lignin and other cell wall constituents, making cellulose and hemicellulose more susceptible to microbial attack. This increases the voluntary intake as well as digestibility of straw.

1. Treatment with NaOH: This process was first used on straw in Germany in 1919, during the 1^st world war, when there was a critical shortage of livestock feed. Straw was treated with NaOH under high pressure and temperature. The product was called “Fodder Cellulose”. This process was costly and used in emergencies. It has 2 types: Wet and Dry.

(a) Wet Method

• Beckmann Method: Proposed in 1921, it consists of treating chopped straw in 8-10 times its weight of 1.2-1.5% (w/v) solution of NaOH for at least 4 hours. This treated straw is washed thoroughly with a large quantity of water until free from alkali. Unfortunately, the treatment dissolved 20-25% of DM from the straw, so a portion of DM was lost. This also causes river pollution.
• Modified Beckmann Method: Torgrimsby (1971) gave a closed system in which the amount of water added to the system is equal to the amount removed in the treated straw. It uses less NaOH and less water, and DM loss is reduced. There is no pollution problem because it is a closed system.
• Dip Method: This method was developed by Sundstol and coworkers in Norway and Tanzania. After draining the excess alkali solution, the straw is ripened for 3-6 days to increase the digestibility of straws.

(b) Dry method

• It was given by Wilson and Pigden in which treated straw is not washed. The straw is sprayed with NaOH while mixed. 4-6 Kg of NaOH dissolved in 200 litres of water is adequate to wet 100 Kg straw. The treated straw is moist and has a pleasant odour. Intake of straw is increased by 30-40%, and digestibility is increased by 10-15% (Jackson, 1977). The dry method can be industrialised. In general, animals suffer no stress if the diet contains less than 4% of NaOH on DMB. This corresponds to 2.5% sodium in the diet.

2. Treatment with Ca(OH)₂: It is cheaper, safer to use and readily available chemical. Ensiling 4 kg Ca(OH)₂ per 100 kg straw with enough water (50% moisture in freshly treated straw) for 90-150 days has resulted in higher fermentability of treated straw. A reduced NDF level increased Ca and CP, and a slightly improved in vitro digestibility of treated straw has been seen (Bui Van Chinh et al., 1994).
3. Treatment with the combination of Ca(OH)₂ and NaOH: Combined treatment produced somewhat better gains either of the hydroxide alone, and treatment with 4% NaOH made significantly greater gains than with 4% Ca(OH)₂. Treatment of straw with Ca(OH)₂ will be effective when the treated straw does not constitute >70% of the diet because the calcium content increases more than the typical requirement (1.5-2%).
4. Treatment with anhydrous NH₃: This method has become famous under Indian conditions for straw treatment. It serves as an essential nutrient (N₂) to rumen microbes to ensure efficient rumen fermentation. Stacks of straw are wrapped with polyethene cover and injected with 3% of anhydrous NH₃ (Sundstol and coworkers,1970-75). However, when materials with high sugar content (5% sugar like hay) are treated with anhydrous NH₃ at high temperature (70%), a poisonous compound ‘4-methylimidasol’ can be formed, which may cause hyperexcitability (Crazy cow/ Angry cow/ Bovine Bunker) in animals and may also be transferred into the milk of dairy cows.

(b) Treatment with aqueous NH₃: 20-35% NH₃ is also used commercially to treat straw. One advantage is that at an NH₃ concentration of about 20%, the solution can be transported and handled at normal temp. and pressure.

(c) NH₃ through urea hydrolysis/ Urea treatment*: Anhydrous or aqueous NH₃ are costly, not freely available, and their transportation is difficult. Fertilizer grade urea can also be used to generate NH₃ from urea hydrolysis. The urea gets converted into ammonia, and then ammonia reacts with the fibre of straw. It improves the quantity of cellulose and hemicellulose for the microbial attack because the small NH₃ molecules can penetrate the interfibrous spaces of crystalline cellulose to break down the H-bridges. Urine has also been used as a source of NH₃ for straw treatment; however, the acceptability of the treated material is somewhat reduced. The poorer the initial quality of the straw or stover, the higher the effect of treatment. This method was developed by Jackson (Pantnagar, UP) and tested and modified at IVRI, Izzatnagar, NDRI, Karnal and at several SAU’s in India. On-farm trials in India have shown that urea-ammonia treated straw offers a great promise for the future of animal production. These studies have also stressed the necessity for a simple and economical treatment system for rural farmer.

Optimum Conditions for Urea hydrolysis:

• Level of urea: The basic principle is the breakdown of urea to its components of NH₃ and CO₂ by the urease enzyme. It was considered a dose of 3% NH₃ optimal, and this corresponds to 5.3% (w/w) urea for treatment, assuming 100% conversion. Animal response to urea treatment is observed with anhydrous ammonia treatment achieved at the same alkali level.

• Moisture level: (Optimum 30-60%): Water act as a vehicle for the ammonia to penetrate the cell walls. An amount of 50 kg water is generally applied at the practical level, and when added to 100 kg of a 90% DM straw, it leads to a final moisture content of 40%. During the urea treatment of straw, the water: urea ratio should be 10:1 for optimum utilization. Below 30%, it would also be more difficult to compress the mass of forage and expel the air. Beyond 50-60 %, there will be leaching of the urea solution towards the bottom layers leading to toxicity risks. Due to the hygroscopic nature of NH₃, it would bind to the water instead of the plant cell walls at high moisture level.
• Preservative effect of NH₃: When the moisture content of straw is 300gm/Kg DM or more, a concentration of urea greater than 40gm/ Kg DM is required to achieve the preservative effect of NH₃. NH₃ has a fungicidal effect (neutralizes the aflatoxin in feed).
• Source and activity of urease: The urease enzyme is a natural contaminant of straw. The ureolytic bacteria produce sufficient urease during the treatment. However, the addition of a urease source (soybean powder, 8.5%) reduced the treatment time from 21 days to less than 5 days. NDDB workers used watermelon seed powder as a source of urease.
• Temperature: The optimum temperature for urease activity in soil is approximately 30°C, and urease activity tends to decrease at temperatures lower than 20°C. IVOMD (in vitro OM digestibility) values were obtained after a treatment period of one to two weeks at 35°C and approximately six weeks at 24°C.

Steps of urea treatment

1. Take 100 kg of straw or stovers and put them on the cemented floor.
2. Dissolve fertiliser grade urea (4kg) in 20-30 lit. of water and mix it till it completely dissolves.
3. Spray the urea solution with any sprayer on the straw lot.
4. Mix urea solution and straw thoroughly with hand fork (about 5-6 turning).
5. Stack under the plastic sheet/gunny bags cover to having the anaerobic condition and allow it to react for about three weeks.
6. Take the straw out from the stack. Give 2-3 turning so that excess ammonia gets evaporated in the atmosphere.
7. Physical aspects of successful treatment: (a) Change of colour from clear yellow to brown or dark brown (dark yellow is not enough) (b) Strong but good NH₃ smell (c) Smooth texture of the straw or stalks, which become easy to twist and bend (d) absence of any mould. The pH of the treated straw measured after 24 hr aeration was 8.86. Efficacy of treatment can be evaluated by chemical analysis and In-Sacco polyester bag technique.
8. Treated straw is ready to use as animal feed for livestock.

Advantages of Urea treatment on the feeding value of wheat straw

1. The ingredients are readily available in the market.
2. It does not cause any pollution problems and not hazardous.
3. Urea treatment of straw leads to increased intake (20-25%) and decreased NDF and hemicellulose content by 8 and 20%, respectively.
4. Urea treated straw is palatable and easily digestible. It can be stored for several months.
5. The butterfat tends to increase with a few decimal points. No residues of urea in milk are observed.

Constraints of urea treatment: non-availability of sufficient straw, urea, or too high levels of animal produce, Sticky dung produced by the animals, pungent smell from ammonia, fear of fungal spoilage of straw in open stacks, water scarcity, price of urea, cost of polythene covering material, labour cost (Owen et al., 2012).

Biological Treatment

The biological treatments are paralleled with decreased CF with high CP content.

1. Enzyme treatment: Enzymes are mainly used in the diets of non-ruminants but are also added to ruminant diets. Enzymes improve feed efficiency by enhancing nutrient availability. They also enhance the consistency of feed that helps maintain gut health, and the digestion process results in overcoming the growth of disease-causing bacteria. We can use them to reformulate the feed. Cellulases can be used to break down cellulose, which is not degraded by endogenous mammalian enzymes. Cellulases solution is sprayed on straw at 25mg/100 Kg straw. Phytase enzymes have more general application as their substrate is invariably present in pig and poultry diets, and their dietary inclusion generates bio-available phosphorous and reduces the phosphorous load on the environment decreased by as much as 50% (Simons et al., 1990; Adeola et al., 2006; Augspurger et al., 2006; Garcia et al., 2005). The digestibility of all amino acids except proline and glycine increased linearly as phytase supplementation increased. β-Glucanase digests fibre and helps in better digestion of heavy cereal grains such as wheat, barley, and rye in the diet. It hydrolyses the glucans present in these ingredients, thus reducing the viscosity of digesta and helps to revitalise natural peristalsis. Proteases are enzymes that degrade proteins. Amylases catalyse the breakdown of starch and sugar. Amylase breaks polysaccharides (carbohydrates) into smaller disaccharides, finally converting them into monosaccharides. Multi carbohydrase feed enzyme and Super enzymes are also available in the market.
2. Fermentation: Chopped straw is pre-treated with 3-5% NaOH, steamed at 120°C for 15 min, then fermented with bran type media cultured with cellulolytic microorganisms at 40-50°C for two days.
3. White Rot Fungi, mushrooms, and microbes (Kim, J. H., M. Hosobuchi., Kishimoto., T. Seki., H.Taguchi and D.D.Y. Ryu, 1995): Common fungi utilised in feeding programs include Saccharomyces cerevisiae, Aspergillus niger, Pleurotus pulmonarius, Antrodia cinnamomea, and Cordyceps militaris. Some of the white-rot fungi like Phanerochaete chrysosporium degrade lignin to the extent of 65-75%, while other fungi like Ganoderma applanatum and Coriolus versicolor degrade over 45% of lignin in the lignocellulosic materials. Preferences are given to species that degrade only lignin but not hemicelluloses. It must be remembered that whatever organism is grown on the roughage must obtain its energy from the roughage itself. They must be capable of growing on a wide range of carbon sources, have high growth rates to minimize the size of the fermentation system, and have high efficiency in converting substrate to biomass with high protein.

*Indo-Dutch project on Bioconversion of crop residues

Studies have been conducted on white-rot Basidiomycetes, often belonging to the non-toxic and edible mushrooms.

• Zadrazil process: Straw was treated with Pleurotus sp. It is unfit for small level operations at the farmer’s level because of enormous organic matter losses.
• Karnal process: It is essentially a biological treatment of lignocellulose in a solid substrate fermentation (SSF) system under non-sterile conditions. It is a two-stage technique wherein cereal straws are pre-treated with 4% urea and 40% moisture and ensiled for 30 days in the first stage and followed by the second stage in which the urea treated material is mixed thoroughly with 1% single superphosphate, 0.1% Ca(OH)₂ and then moisturize to 60-65% before inoculation with 3% Coprinus fimetarius (alkali tolerant strain) culture grown on millets. The solid substrate fermentation was terminated at the mycelial stage of growth fimetarius. The use of urea in the first stage has many advantages. Besides breaking the ligno-carbohydrate bonds in the treated straw, ammonia also helps in creating a conducive environment (high pH), increases CP content from 3-4% to 12-14% and acts as a chemical sterilant in preventing the growth of unwanted organisms. In the second stage, the fungus traps the excess free ammonia in the urea-treated straw and synthesize amino acids. Thus, there was a substantial increase in the amino acid content of fungal treated straw.

The following methods deactivate various ANFs (Anti-nutritional factors) in feeds:

Conclusion/ Future

As the world population is expected to increase from 6 to about 8.3 billion in 2030 at an average growth rate of 1.1% per year, it is essential to be prepared to produce sufficient food products for the increased population-based on improved quality of feed resources, especially in the developing countries. Thus, present and future livestock nutrition and feed resources improvements are now being directed at using feed processing technology and nanotechnology in livestock nutrition and feeding. Future nanoparticles like the novel ‘Silver-Silica’, Cu nanoparticles may have to be used alongside antibiotics. Techniques of modern biology such as biotechnology, chemical and biological treatment of low-quality animal feed for improved nutritional value have become a reality in the past few decades. Urea treatment and multi-nutritional blocks represent the simplest and easiest way for optimizing PQR in ruminants and widely used in practice. Biotechnology has a role in animal feed improvement in three main ways: value-addition to forage used as animal feed like transgenic forages, production of feed additives (Antibiotics, Enzymes, probiotics, prebiotics) (Ramirez, 2014) and manipulation of rumen microbes like defaunation (protozoal elimination). Designer ingredients that could be applied in designing genetically engineered plants and forage crops to introduce or enhance a desirable characteristic in the plant or seed-like plant genetic modification with genes encoding for a Sulphur amino acid-rich protein, high oil and low phytate maize, manipulating lignin composition and levels in alfalfa to improve their digestibility. Food products derived from animals fed with transgenic forage crops are safer than when humans consume directly modified crops.

There could be the development of carefully balanced partial or total mixed rations. While using TMR, each bite is nutritionally balanced, roughage to concentrate can be varied to regulate nutrient intake, control rumen pH, enhance microbial protein synthesis, minimize feed selection, increase feed intake, reduce labour cost. The level of education or extent of contact with extension services is essential to adopting new technologies. Livestock development agents are required to engage in months of extensive crop production activities (Klerkx et al., 2010).

So a ‘joint approach’ of research, extension and financial institutions and private sectors like local feed manufacturing and agro-pharmaceuticals companies is necessary, including farmers, nutritionists, and dairy scientists. Collectively, these approaches will facilitate the adoption of feed technologies, improve livestock productivity, and contribute to reducing food and nutrition insecurity problems in developing countries. Further research is needed to identify new hope for feed additives and recognize how combinations of these additives can improve livestock production efficiency.

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