Use of Low Quality Crop ResiduesLow quality fibrous crop residues include straws, sugarcane baggasse, hulls, corn cake, etc. These are very low in digestible energy and protein and are highly lignified. There slow turnover in the rumen results in rumen fill becoming a limiting factor. Crop residues contain insufficient nitrogen to support adequate microbial growth in the rumen.

Treatments to improve utilization of crop residues:1. Chemical Treatment : Signification of the cell wall material is the main factor responsible for the very low digestibility of fibers crop residues. Lignin is very indigestible and by encrusting cellulose and other cell wall contents, impedes their digestion too. However, lignin is very respectable to degradation by oxidation and is destroyed by oxidizing agents such as hypochlorite and sulfites. These products are used in the treatment of wood pulp to isolate cellulose for the purposes of paper manufacture. Alkali dissolves lignin and readers the cell wall constituents susceptible to several disadvantages in addition to cost: the need for supplemental nitrogen, the increased sodium load on the animal, sodium contamination of soil, and the hazardous nature of the chemical.An alternative is ammoniation. Ammonia treatment, either as ammonium hydroxide or gaseous ammonia is effective in dissolving lignin, and improving fiber digestibility. It also provides a source of supplementary nitrogen. Ammonia is an effective preservative, and is safer and easier to use. The color of the treated straw is changed to intense yellow-brown; and is more easily reduced to small particle size, facilitating its digestion.

Urea can be used as a some of ammonia, and most roughage have sufficient bacterial urease present to convert urea to ammonia. Ammoniation reduces effects of aflatozins. It also reduces glucosinolates is mustard meal.

Toxicity of Ammoniated Roughages:Ammoniation of feeds may produce toxins and toxicity symptoms in animals consuming such treated feed.

This toxicity has been named as bovine hysteine, bovine bonkers, ammoniated hay toxic-sis, hyper excitability, or crazy cow syndrome. Neurological signs, such as hyperactivity, incardination, tremors and cowulsions occur in affected animals. Cattle may become extremely nervous and difficult to handle. Affected animals may suddenly gallop in circles and sun into fences, gates, and other objects, often causing them selves injury. The causations factor appears to be a 4-methyl-imidizole, formed by the reaction between reducing sugars e.g. glucose and ammonia in the presence of heat. Toxicity does not occur if the temperature of the ammoniated roughages remains below 70C during ammoniation. Ammoniation of molasses may also produce bovine hysteine. Because of the involvement of reducing sugars, amoniation of good quality roughages with abundant reserves of cartbohyohates should be avoided.

Other Chemical Treatment:Treatment of low quality roughages with alkaline hydrogen peroxide solution increase digestibility. In this treatment, the lignin carbohydrate bends are disrupted, which increases accessibility of the cellulose to cellulolytic enzymes, increasing cellulose digestion. Treatment of roughages with ozone has also been shown to degrade lignin and improve fiber digestibility.

Physical Treatment

The digestibility of low-quality roughages can be improved by grinding or chopping the material. However, these benefits are usually offset by a more rapid passage of small particles form the rumen, escaping menial digestion. The major benefits of chopping are reduced feed wastage.

Lignin can also be degraded by various aerobic fungi and bacteria.

Improvement of the Rumen Environment:Low quality roughages lack adequate fermentable nitrogen, true posteine readily available carbohydrates, and minerals for optimal microbial activity. Slow rates of fiber digestion and outflow from the rumen are major constraints to increasing voluntary intake of poor-quality roughages. Supplementation of low-quality roughs with ground alfalfa hay improves fiber digestibility and rumen environment parameters, such as concentration of branched-chain fatty acids and ruminal ammonia nitrogen. Readily fermentable cell wall constituents of alfalfa might stimulate cellulolytic microbes with colonization of the poor-quality roughage. The positive effects of by pass protein on intake of low-quality roughages are well-known.

Feed additives and their use in livestock feeding:Feed additive is an ingredient or combination of ingredients added to the basic feed mix to full fill the specific used. It may also be defined as any chemical incorporate in an animal feed for the purpose of improving rate of gain, feed efficiency, or preventing and controlling disease. A feed additive need not to be a drug.

Types of Feed Additives:Feed additives can be a classified into nutrient feed additives e.g. amino acid, minerals and vitamins, and non-nutrient feed additives e.g. antibiotics, hormones, commomodulators, coccidiostate, enzymes, probiotics, yeast acidifiers, antioxidants, mycotoxin binders, anticaking agents, feed preservatives, plavoring agents, cloring agents, pellet binders, dietary baffers, methane inhibitors, propionate pronotors, defamating agents, heptoses and bloat controlling agents, surfactants, sweetening agents tranquilizers, emulsifiers and stabilizers, etc.

Advantages of Feed Additives:1. Improve feed quality and palatability.2. Improve animal performance3. Improve the final product4. Economize the production costs

Negative aspects of Feed Additives:Hormones and antibiotic have residual effects in meat, milk and eggs. Feeding of low concentration of antibiotics may favors the proliferation of antibiotic resistant microorganisms. Use of antibiotic in ruminants, feed is not common in Pakistan.

Poultry:Antimicrobial feed additives are included in the diets for the prevention and control of coccidiosis, etc. and to improve growth, efficiency of feed utilization, livability and egg production.

Ionophore Antibiotics:These are produced by several strains of streptomyces species e.g. Monensin, Lasalocid, Salinomycine, Hysocellin, which are antomiesobial compounds. Morensin is an

anticoccidial agent for broilers, lambs and beef cattle. It improves feed efficiency and not growth. Heifers having more than 180 kg body weight can be fed 50 to 100 mg/head/day by mixing in about 500 grams of feed. It impact is better in low protein diets.

Effect of ionophores on Rumen Fermentation:1. It increases the rumen propionate and decease acetate concentration.2. It deceases methane production3. Depress the activity of some rumen enzymes like proteases, deaminases, and

urease.4. Decrease the passage rate of feed; thus increaring the ME value per unit of feed

intake. (10%). Both monessine and lasalocid inhibit the growth of ruminal microbes which produce acetate. Butyrate, lactate. Formate and hydrogen as major and products. Other organisms which produce succnate and propionate or utilize lactic acid would grow rapidly in the preauce of ionophores. The production of increased levels of propionic acid in the rumen is related to improved animal performance. Propionate has protein spening effect and stinulate body protese synthesis and thus improve growth promoting activity.

Lasalocid (Trade Name: Bovitec):It is produced by fungi streptomycin lasoliensis and is more protest than monensim. It acts against hydrogen producing bacteria and results in higher propionate production. Its dose is 1 mg per kg body weight or similar to monensin.

Benefits of growth promoting antibiotics in animal feeds include: better weight gain, higher feed conversion ratio and less meruse with lower N and P content. Tetracyclins, oxytetracyclins and chlortetracyclins are absorbable antibiotics. Nonabsorbable antibiotics are zinc bacitracin, anoporcin, monensin, virginiamycin, etc which have beneficial effects on the microflora of the intestinal tract. As per the latest European union regulation (folloved for Setember 1999) only monensin, salinomycin, flevomycin and avilamycin are the from feed grade pharmacentrial antibiotics remaining on the approved list.

Arsenicals improve growth of broilers and such birds have bright red combs and wattles. Arsenicals must be removed from the feed 5 days before slaughter. Accumulation of arsenic in eggs and tissues is proporational to the amount in the ration and well below the allowable levels. Arsanilic acid is tolerated upto 0.1% in the diet of chicks and upto 0.02% in the diet of turkeys. Arsenicals should not be included in the rations of the ducks and gees.

Hormones:The active principles sesected by the endocrine glands into the blood for transporation to target organs and tissues are known as hormone. The two broad types of hormones include:

1. Anabotic hormones e/g/ somatotropin, thyroxine and androgens.2. Catabolic hormones e.g. oestrogens, glucocorticoids.

Hormones as carcass modifiers:Intact males produce less fat and more lean from a given feed than either the females or the castrate males. Bulls contain less subcutaneons fat intermusuclar fat than stears. Anabolic agents evhance nitrogen rectention in the body and particularly in the muscle, and result in production of leaver carcasses. Androgens are mainly used in females and castrated males while estrogens are used in males.

Anabolic steroids:There are banned in EU since 1989, because of health problems they might cause. These include: oestradiol, tranbolone acetrate (TBA), Zeanol (Ralgro)+TBA.

Somatotropin:It is a polypeptide and therefore not orally actic and it is species specific. Hence the little, if any, sometotropin present in animal products get degraded in the GI tract and thus has no influence on human health. Somatotropin and growth hormone (GH) can be used interchangeably. The secretion of this hormone is enhanced following feeding of protein. Somatotropin influences the biosynthesis of protein in the muscles; increase N setention; increases skeletal growth and improves growth and milk production.

Exogenous Bovine Somatotropin (BST) injections:A greater negative energy balance of often observed in cows during the first few weeks after beginning the administration of bST, but cows gradually increase their feed intake to obtain the required nutrients for body weight gain and increased milk production. High yielding cows treated with daily s/c injections of b St (12-50,g) gave 20 to 40% increase in milk yield and 12-14% increased feed efficiency. The increase in milk yield were associated with increase sin feed intake.

The availability of slow relaease device of bST has eliminated the necessity for daily injection. Lactating cows injected 640 mg bST at 28 Day intervals for a period of 112 days gaine 12 to 15% higher milk yield over control animals. Levels of ST in milk produced by treated cows are axcedingly low and constitute no threat to the uman consumer. In beef cattel steroid implants and somatotsopin produced additive increases in performance of finishing steers. In growing lambs chronic administration of ST for 12 weeks led to a 20% increase in rate of daily gain. However, some negative impacts on reproductive performance have been reported.

Growth Promoters for Fattening Ruminants:In the EU, the recommended doses for fattening cattle are 20-60mg/kg feed for nomensin with optimum of 30. Ionophores improve average daily gain and feed conversion efficiency of growing kids by 10%. Ionophores supprescoccidisive; increase propionate /acetate ratio.

Amprolin, clopridol, hasalocid sodium, monensin sodium, slinomycine, robenidine, meduremicin, narecin, etc act as coccidiostates.

Several hormone implants viz oestradiol, trenbolone and testosterone are used in animal production, but are banned in EU.

Anabolic steroids and growth hormone use has been banned in the EU, and also banned meat imported from countries such as USA, when growth hormone is used to achieve improved efficiency and leaner carcasses.

Feed Enzyme Additives:These act as biocatalysts to assist the digestion process and support the utilization of nutrients that otherwise go unused.

The predominant non-starch polysaccharides in cercal grains are cellulose, arabinoxylans and betaglucans.

Feed enzymes such as B-glucanases and xylanases have enabled barley or wheat in poultry diets up-to 50 or 50%. Arabinases, xylanases and pectinases breakdown the arabinoxylans and pectin’s present in sunflower seed meal, rapeseed meal, etc. and release the protein and other nutrients; and bring the nutritional value of sunflower meal equal to soybean meal.

A multi-enzyme preparation with cellulolytic and photolytic activity (celluloses, B-glucanases and protease) can degrade the structural polysaccharides and proteins. Phytase enzyme helps to increase the utilization of phytin P by poultry etc.

“Fibrozyme”, (alltech) in the first feed-grade enzyme that is rumen stable. It significantly increases DM digestibility VFA production and carbohydrate utilization in cattle fed high amounts of fiber. Feeds containing fibrozyme can be pelleted with only a slight loss in enzyme activity.

Probiotics, Yeast Culture and Acidifiers Probiotics are defined as “organisms and substances which contribute to intestinal microbial balance”. The terms probiotic means “for life” in contrast with the term antibiotic means “against life”.

Protiotics are advocated as an alternative to antibiotics for growth promotion. Probiotics are live cultures of non-pathogenic organisms which are administer orally. Later probiotics were redefined as live microbial feed supplements which beneficially affect the host animal by improving its intestinal microbial balance. Probiotics are available in the form of oral pastes, water dispersible powders or liquids or directly fed feed additives and include microbial cells, microbial cultures and microbial metabolites. Most probiotics get destroyed by upto 80% in the presence of antibiotics. The term “pronatrient” is used in place of probiotics. The US Food and Drug Administration used the term direct fed microbial (DFM_ instead of probiotic.

Micro-organisms used as Probiotics:Some important are: lactobacillus acidophilus, L.bifidus, :. Bulgaricus, L. casei. L. fermentrim, L. lactis, L. plantarum, L. ruminis, L. salivaricus, Bifido bacterium bifidum, Aspergillus oryzae, Torulopsis, Streptococus faecuim, s. thermophilus, Saccharomyces cervisiae.

Lactobacillus acidophillis produce lactic acid and the enzyme amylase. Lactobacillus casei complements the growth of L. aciclophillus. Bifido bacterium bifidum is commonly found in mother milk and the intestine of humans and animals.

Aspergillus oryzae produce enzyme cellulose. Torulopsis is the mother culture of yeast. The enzyme lipase is exhibited by Torulopsis. Probiotics at the specific concentration stimulate immunity. A low pH (4-5) favours lactobacillus sp. And a high pH (6-7) is optimal for E.coli.

Shortly after hatching, the chick has a nearly sterile digestive tract with a pH rauge of 5.5 to 6.0. So supplementation of a lactobacillus product in the water or feed along-with an acidifying agent would be effective in controlling the coli-form proliferation.

Yeast Culture: It is known to contain compounds formerly refessed to as UFGs which positively affect animal performance rumen bacterial concentrations increase when fermentation products such as yeast cultures are added to the diet. Metabolites in the

fermentation products serve as nutrients for the bacteria. Byproducts of fermentation include dried brewers yeast, dried distillers soluble, dried bacterial press cakes.

Yeast cells are destroyed by pelleting the feed, storage conditions and strong mineral mixtures. Significant losses of variable yeast cells canals occur over time for yeast products hold at 35oC in paper bags. The rate of deterioration is time and temperature dependant.

Inclusion of live yeast cultures in the diet (3 to 5g/d) decreases body temperature and respiration rate in hot, but not in cool weather. It also act by production of growth stimulating factors in the rumen. Stabilizing rumen pH and reduction of lactic acid production, and increasing rumen bacterial population.

Yeast culture increases rumen bacterial population, which in turn will increase flow of microbial protein, as well as increase degradation of fiber in rumen, leading to increased feed intake, and thus ultimately increasing animal productivity.

Yeast culture may increase milk yield (8%); with more response during early lactation. Responses increase as the ratio of concentrate to forage in the ration increases. Total butter fat and milk protein also increase. Inclusion of yeast in the diet of cows fed a 60% concentrate and 40% when straw was replaced by hay. The addition of yeast culture to diets containing 40 to 80% oat straw increased in sites NDF digestibility in steers. Acetate was reduced which propionate was increased by yeast addition. Ruminal protozoa numbers increased in steers fed yeast culture. Total and cellulytic bacteria were higher in ruminal fluid of calves fed yeast culture.

White rot fungi decompose lignin or lignocelluloses with minimal degradation of hemicelluloses and cellulose. Yeasts are always found in culture of white rot fungi. The potential synergism between yeast (S. cerevisiae) and fungi (Armillaria heimii) had the best potential for increasing forage digestibility. Inclusion of yeast culture diets given to yearling horses.

Supplementation of broilers diet with live yeast culture (1 kg/ton) may increase weight gain and FCR. Combined use of lactobacillus and yeast culture in the feed and water may be effective in reducing morbidity and mortality and improving growth performance and production.

Direct-fed microbial include:Lactobacillus, streptococcus, Bacillus and yeast (saccharomyces cerevisiae). Lactobacilli are delicate microbes that are unable to withstand various environmental extremes, such as the heat and pressure of pelleting. Bacilli are very stable microbes that can survive pelleting. Yeast and streptococcus fall somewhat between lactobacillus and bacillus in their ability to survive pelleting. The ability of the yeast to grow in the rumen is limited, but is able to remain alive and metabolically active in the rumen and postruminelly. DEF, are designed to prevent or reduce E.coli scones in calves. The rational for their use in the calf is that feeding live, non-pathogenic bacteria may displace and suppress intestinal pathogens. DFMs may be of little benefit under good rearing conditions and husbandry practices. Stress such as extreme weather or transportation, would more likely enhance the potential benefits of feeding a DFM to calves.Acidifiers: Organic acids usually are added only as preservations, but they do positively influence performance when included at higher quantities.

Liquid acidifiers are : 1. Formic acid- 6-8kg/ton2. Prop-ionic acid- 8-10kg/ton

Organic acids in powder form are:1. Fumaric acid 12-15kg/ton2. Citric acid 20-25kg/ton.

In diets for laying hens, the feed additive calcium format (1.3%), which is converted to formic acid in the crop, offers potential benefits beyond reducing E. coli and salmonella populations. It inhibits molds; improves consistency of droppings, resulting in fewer dirty eggs; better calcium absorption and egg shell quality. It is stable in storage, safe in food and the environment and without negative effects for other feed supplements, such as vitamins, etc. Calcium format is non-corrosive, odor free and non-caustic. It approved by EU for use as food and feed preservation.

Antioxidants: Oxidation of feed fats causes rancidity spoiling the taste and flavor of the feeds thus a process known as lipid per-oxidation or autoxidation these rained fat containing diets impart undesirable off flavor in the milk and milk products. Oxidation also causes much loss to carotenes; vitamin A and vitamin D. the use of antioxidants limit this oxidative spoilage. Oxidation negatively affects odor, taste and nutritive value of the food, as well as produces harmful by-products. The addition of antioxidants map up the free radicals. Antioxidants may be natural and synthetic. National ones are vitamin E (tocopherol) and ascorbic acid. The most common synthetic antioxidants are ethoxyquin, butyrate hydroxyanisole (BHA) and butylated hydaroxytoluene (BHT). BHT and BHA tend to be more effective in preventing oxidation of animal fats than of vegetable oils which ethoxyguin is most effective in protecting both animal fats and vegetable oils.

Mycotoxin binders: these chemicals are harmful to animals and humans. The major mycotoxin producing fungi are aspergillums, Fusarium and penicillium and the toxins are aflatoxins, zeralemone, trichothecenes, fumonisins, ochratoxin A, etc. Mycotoxin binding agents include activated charcoal, yeast cell wall products, synthetic zeolites and mined mineral days such as aluminosilicates, sodium betonies.

Anticaking agents: these are substances that can pick up moisture without themselves becoming wet. They are added to dry mixes to prevent the particles clumping together and so hup the product free flowing. Anticaking agents include: calcium star-ate, calcium phosphate ferrous ammonium citrate, yellow prussiate of soda, potassium or sodium ferrocyanide, magnesium oxide, kaolin, ball clay, sodium aluminum silicates, hydrated sodium calcium alluminosilicate (HSCAS), calcium aluminum silicate, etc.

Preservatives: The aim of preservatives is to prevent microbial spoilage. e.g. nisin, benzoic acid, methyl-4-hydroxybenzoate, cthyl-4-nitrate, prop-ionic acid, sorbic acid and sulphur dioxide.

Antifungal agents: Sodium propionate, sodium benzoate, nystatin, etc.