Straw Enrichment: A Boon to Dairy Industry

November 16, 2023

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Straw Enrichment: A Boon to Dairy Industry

Straw enrichment has emerged as a transformative practice in the dairy industry, offering a range of benefits that extend beyond traditional cattle management approaches. This article delves into the significance of straw enrichment in promoting animal welfare, improving environmental sustainability, and enhancing overall herd health in the dairy sector.

India, with only 2.29 % of land area of the world, is maintaining nearly 17.4% of human and 10.7% of Livestock population of the world. Growing demand for livestock products by the increasing population and urbanization is one of the major factors responsible for the steady growth of the livestock sector. In view of the current shortage there is an emergent need to enhance the nutritive value of the limited feeds and fodder. Resource wise dry fodder represents the largest amount followed by the green fodder, and the concentrates. Dry fodder mostly comprises of crop residues and is obtained as a byproduct after harvesting the food grains. Crop residues have low palatability, nutritionally poor and have to be supplemented with green fodder or concentrates. Therefore, to improve the productive and reproductive capacity of ruminant animals on small-holder farms, there is a need to develop feeding strategies that will enhance the quality and availability of feed resources. Straw treatment increases the accessibility of low quality forages to the digestive enzymes of the rumen’s microorganisms so as to improve both their digestibility and intake. These treatments are, in fact, very efficient and some of them emphasized below are extremely easy to put into practice.

CHEMICAL TREATMENTS: · Oxidizing agents (peroxyacetic acid, acidified sodium chloride, ozone, etc.) which decompose fairly efficiently the lignin but are limited in use because they are costlier and some are harmful and corrosive. · Strong acids · Alkali based agents (lime, potassium, caustic soda either alone or in association and, more recently, ammonia), which are able to hydrolyze the chemical bonds formed between the indigestible lignin and the parietal polysaccharides (cellulose, hemicellulose). The combined effect of these treatments is to cause a reduction in the rigidity of the cellstructure and a swelling of the cell wall. Thus microbes can colonize more rapidly on the vegetal matter, decomposing it more quickly and intensively increasing its dry matter degradability. Due to the potential dangers involved with caustic soda treatment, these techniques havealmost entirely abandoned in favour of treatment with ammonia. Ammonia (NH3) is a byproduct from industrial “cracking” of hydrocarbons. It is used as a raw material in the fertilizer industry and also applied directly as a fertilizer. It is a gas at the normal atmospheric pressure. It is easy to liquefy and readily dissolves in water. Due to the volatility of ammonia at normal room temperature and pressure, treatment with anhydrous ammonia presupposes that the forages will be treated within hermetically sealed enclosures. Ammonia gas can be added to both dry and ensiled forages. This technique offers no advantage for treatment of legume hays, and often may result in a toxic feed for livestock when high quality, immature forage grasses, sudangrass or small grain hays are ammoniated because of the increased absorption of ammonia from rumen wall. Lower quality crop residues are treated with urea as it is a cost-effective way of improving their feeding value in terms of their voluntary feed intake, dry matter and crude protein degradability. Ammonization increases crude protein (CP) and improves forage digestibility.

The Principle and Effects of Straw Ammoniation

The main component of straw is fibre, including cellulose and hemicellulose that can be digested by ruminants. Some cellulose and hemicellulose are bound to lignin and resistant to microbial attack. Ammonia treatment substantially reduces the concentration of neutral detergent fiber in forages. Most of the loss of NDF is due to destruction of hemicellulose. Ammoniation also reduces the amount of lignin in some forage. Ammonia treatment disrupts chemical linkages between lignin and hemicellulose. Lignin inhibits fiber digestion; therefore, disruption of those linkages makes the hemicellulose more digestible. Cellulose digestibility also increases since lignified hemicellulose encases cellulose. Ammonia treatment also changes the physical characteristics of forages making them more pliable and increases their uptake of water (hydration). Hydration rate has an important role in digestion rate; the faster a forage particle is hydrated, the faster it is digested. Thus Ammoniation usually increases digestibility by 20 percent and CP content up to 1-2 times. It can also improve palatability and consumption rate. The total nutritional value can be doubled. In addition, ammoniation reduces mould development, destroys weed seeds (e.g. wild oat, false sorghum, etc.), parasite eggs and bacteria.

Ammonia sources for Straw Ammoniation

The sources of ammonia to treat straw include anhydrous ammonia, urea, ammonium bicarbonate and aqueous ammonia.

Anhydrous ammonia

Anhydrous ammonia means “ammonia without water.” Its formula is NH3, and its N content is 28.3 percent. The normal dosage is 3 percent by weight of the straw DM.The boiling point of anhydrous ammonia is -33.3°C, its vapour density is 0.59 (that of air is 1) and its liquid density 0.62 (that of water is 1). Gas pressure is 1.1 kg/cm2 at -17.8°C and 13.9 kg/cm2 38°C. At normal temperature and pressure, anhydrous ammonia is a gas. Expensive pressure containers are required not only to keep it as a liquid, but also to transport and store it. Anhydrous ammonia is a potentially dangerous and toxic material, and stringent safety precautions need to be observed when using it. Its natural ignition temperature is 651°C. If the ammonia content in the air reaches 20 percent, an explosion from selfignition could occur. Attention should be paid to possible ammonia explosions, even though it seldom happens.

Urea

The N content of urea is 46.7 percent. Its formula is CO (NH2)2. It is decomposed into ammonia and CO2 by ureases at ambient temperature.

The chemical reaction is: CO(NH2)2 + H2O 2NH3 +CO2

The recommended dosage is 4-5 percent urea on DM basis, taking into consideration the effect of ammoniation and costs. Urea can be transported conveniently at normal temperature and pressure. It is harmless to humans. Treating straw with urea does not need complex equipment and the sealing conditions are not as strict as with anhydrous ammonia. Urea is not as effective as anhydrous ammonia for straw treatment, but it is better than ammonium bicarbonate. Thus Urea treatment is the most economic and easily done treatment method to enhance the nutritive value of poor quality fodders. Key Points regarding Urea: · Easy availability. · Urea spray makes the Wheat Straw soft and easy to digest. · Cheap way of increasing proteins. · It has a number of beneficial effects on the quality of fodder and growth of the animals, with no side effects.

AMMONIUM BICARBONATE The nitrogen content of ammonium bicarbonate is 15-17 percent; its formula is NH4HCO3. It can be decomposed into NH3, CO2 and H2O at a suitable temperature (above 60°C).

The chemical reaction is: NH4HCO3 NH3 + CO2 + H2O

The dosage of ammonium bicarbonate, estimated by its N content, is 14-19 percent of straw DM. Ammonium bicarbonate is a major product of the fertilizer industry and it is readily available at low price and it is easy to use. Since ammonium bicarbonate is an intermediate product of urea breakdown, theoretically, in the right concentration, its effect should be similar to urea It does not decompose completely at low temperature, thus in cold climates the effectiveness of treatment with ammonium bicarbonate is not good. When treating with ammonium bicarbonate in an oven, one day is enough, since the temperature reaches 90 °C and it decomposes completely.

Aqueous ammonia

Aqueous ammonia is a solution of ammonia in water. The concentration is quite variable, but the usual value is 20 percent. At this concentration, the normal dosage is 12 percent by weight of straw DM. It is only adapted to areas near to fertilizer factories because its low N content makes transport expensive.

Other sources

Besides the above sources of ammonia, human and animal urine also can be used to treat straw. Urine can be used as a source of urea. In effect, although it consists of 90 to 95 % water, urea is the most important of the solid constituents and makes up more than 70 % of the nitrogen content in the urine. For domestic mammals, the urea content of urine ranges from 2 to 25 g/litre. One of the reasons why this treatment method has not really been used extensively from the purely practical difficulties involved in collection and storage of the urine.

Reason for low nutritive value of Straw

The degradation of the cell walls requires the microbes to attach themselves to the feed particles so that the enzymes can penetrate inside the fibrous structures. But wheat straw shows a high proportion of lignified walls, incrusted with lignin in a very complex manner ,the lignified walls resist for a long time the microbial degradation and the peristatic mastication (of rumination) and they are thus only digested slowly. Thus in order to have good digestive utilisation, the cellulolytic fermentation process should be correctly carried out, the microorganisms in the rumen must be able to find the nutritive elements which they need for self development and to enable them to degrade the polysaccharides of the cell walls of the wheat straw .

Nutritional Value Enhancement of Straw with Urea:

As straw especially Wheat Straw is not easily digested that’s why it cannot be eaten in a large quantity, and also it does not fulfill the nutritional requirements of animals. For this reason it is treated/ enriched to improve its nutritional value. The quantity of the proteins in the Wheat Straw increases when only urea is used in the preparation but when molasses is mixed with Wheat Straw, then in addition to increase in protein value, its energy content is also increased and animals get more energy. Ammonia treatment (3%) of dry forages generally increases the CP content by about 8 percentage units. Ammoniated straw will contain 12-14% CP as compared to 4-6% for untreated straw. Inclusion of urea is associated with increase in digestibility of OM and increase in the voluntary intake of OM. The volatile fatty acid (VFA) pool in the rumen is also higher in treated straw. The increase in digestibility coupled with the increase in feed intake results in a substantial increase in consumption of digestible energy by animals fed ammoniated forages as compared to those fed untreated forage. In other words, ammoniated straw can provide adequate energy and protein to maintain cattle and sheep under most conditions. Ammoniated fodder is generally adequate in energy and protein but mineral and vitamin supplementation especially Vitamin A and sulfur adequacy should be examined closely.

Wheat Straw Enrichment Process:

Step 1: Chaffing of Wheat Straw Wheat Straw is procured and chaffed

Step 2: Adding of Urea Dissolve 4 kg Urea in 50 litres of water. Since urea is not easily dissolved in water, so add it in water in small quantities, stirring it continuously, this mixture would be enough for 100 kilograms of Wheat Straw.

Step 3: Spraying of Urea Solution Now spread about 9-10 inches of Wheat Straw on the ground and spray the Urea solution on it and mix up the Wheat Straw. Spread the second layer on it and repeat this process. In this way, spray the whole of the solution on the Wheat Straw and press it to remove the trapped air.

Step 4: Covering After that, cover it with a plastic sheet to protect it from air and moisture. If a plastic sheet is not available, cover it with anything like a thatch mat and mud. Mud alone can also yield the required results. Ensure that the moisture in it is not more than 50%. The ideal temperature for all this process is 30-35°C. In the other process, molasses is also used with urea For 100 kilograms of Wheat Straw, 4 kilograms urea is mixed with 50 litres of water and then 10-15 kilogram molasses is added to this mixture. The remaining process is the same. This mixture mixes easily and completely if it is sprayed during threshing at the point where Wheat Straw emerges from the thresher. Cover the Wheat Straw with a plastic sheet after the spray. Keep the Wheat Straw under the plastic cover for 3 weeks to protect it from moisture.

Changes in the Wheat Straw after Urea Treatment:

When Wheat Straw is kept covered in this process, urea is converted into ammonia gas which darkens the colour of the Wheat Straw, thus increasing the proteins in it and making it easily digestible for the animals. Urea also acts as fungicidal to the final product. Urea treatment dissolves the carbohydrates (mainly the hemicelluloses) partially thus swelling the vegetal matter in an aqueous environment, so easing access by the rumens cellulolytic microorganisms and reducing the physical strength of the cells, so easing mastication by the animal and digestion by the microbes and enriching the forage in nitrogen. During summer place the Wheat Straw in an open environment for some time after a 20-day treatment so that the extra ammonia and its smell disappear, before feeding it to the animals. Feed 4-5 kilogram fodder daily to pregnant and lactating animals, and even to those which are non lactating animals. Use the straw by mixing it with green fodder, so that nutritional requirements of the animals are fulfilled.

Precautionary measures during Treated Straw Feeding: · The calf six month should not be fed with treated straw. The pregnant cattle should not be fed with treated straw. · The quantity of the urea should be appropriate during the preparation. · It is also important to ensure that urea is dissolved well in water. · Provide a lot of water to the animal. The cost of the Straw Enrichment process is 60 paisa per kilogram as the cost of urea is 10-15Rs/kg but the use of enriched straw increases milk production by 20%. It means the rate of profit is much higher as compared to the cost.

Beneficial modification to Urea Treatment of Straw:

Urea along with calcium sulphate: However, inclusion of high amount of urea in the poor quality roughage is still limited because of the rapid hydrolysis of urea to NH3–N and absorption from the rumen. This could result in a potentially large part of the N excreted in the urine and faeces as a loss of potential nutrient for production; thus can contribute to environmental pollution .Slow release urea has been achieved by binding urea to calcium sulphate and could improve N utilization in the rumen in increasing microbial protein synthesis as well as milk production in ruminants found that the inclusion of Urea-calcium sulphate at 180 g/kg DM in the feed block could improve in vitro rumen fermentation, microbial mass and digestibility.

Urea along with Calcium hydroxide:

Although, urea-treated (5%) rice straw has been used as roughage during the dry season but the cost was relatively high due to increasing price of urea. Elseed et al. (2003) suggested that when amount of urea was reduced and combined with calcium hydroxide Ca (OH)2, it could improve rumen degradability. The concentrated alkaline agents can chemically break the ester bonds between lignin and hemicellulose and cellulose, and physically make structural fibers swollen. These effects enable rumen microbes to attack the structural carbohydrates more easily, increasing digestibility and at the same time increasing palatability of the treated straw. Moreover, calcium residue which remained in the treated straw causes no serious problems to the animal or environment and can be a calcium supplement to the animals. Based on this study, implications could be made that using 2.2% urea+2.2% calcium hydroxide treated rice straw for straw treatment could be an alternative treatment with regards to its effectiveness and treatment cost.

CONCLUSION

It is clear that urea treatment constitutes a simple and efficient technique which can be used practically in the farms. Essentially, one should consider all the factors, which might influence success and any constraints, which have to be overcome. Urea treatment does not pose difficulties as long as it is carefully done. It constitutes a practical technique which may be used with equal success for small farmer communities, as well as by cooperatives or large farms to improve the nutritive value of the straw and thus to increase animal productivity and overall profitability of the dairy venture. Straw enrichment stands as a boon to the dairy industry, addressing multiple facets of modern cattle management. From promoting natural behaviors and environmental sustainability to improving animal welfare and overall production efficiency, the incorporation of straw enrichment aligns with the evolving expectations of consumers, regulatory standards, and ethical considerations. As the dairy industry continues to embrace sustainable and ethical practices, straw enrichment emerges as a simple yet impactful solution for fostering a healthier, happier, and more sustainable future for dairy cattle and the industry as a whole.

Enrichment & Densification of Crop Residues