OM

Animal Feeds and Feeding Practices – Grade 11

Learning Outcomes

  • By the end of this unit you should be able to:

    • Identify local animal–feed resources and their major types.

    • Categorize feed resources into roughages vs. concentrates.

    • Explain nutrient requirements (maintenance, growth, reproduction, lactation, work, health).

    • Describe the six basic nutrients – carbohydrates, fats, proteins, minerals, vitamins, water – together with functions & common sources.

    • Analyse economic, agronomic & animal‐based factors affecting ration formulation.

    • Formulate balanced rations by the Pearson Square method.

    • Demonstrate two main conservation techniques – hay‐making & silage – plus their step-wise operations.

    • State & outline the industrial flow of compound feed manufacturing (raw-material reception ➜ storage ➜ weighing ➜ grinding ➜ mixing ➜ pelleting / crumbling / bagging ➜ quality control).

5.1 Feed Resources in Ethiopia

  • Animal nutrition = science of preparing & supplying feed.

  • Feed cost is the largest single expense in livestock enterprises: 50\%–80\% of operating cost, depending on location.

  • Overfeeding = wastage & higher cost; underfeeding = poor performance & reduced profit.

  • Four broad Ethiopian feed resources:

    • Natural pastures (seasonal grazing).

    • Crop residues.

    • Cultivated forage crops (improved grasses & legumes).

    • Agro-industrial by-products.

5.1.1 Natural Pasture

  • Self-growing grasses, shrubs & browse; provide >60\% of total feed.

  • Cheapest delivery system = direct grazing. Quality high in wet season, declines in dry.

  • Key management: stocking-rate control (avoid overgrazing), fertilizer application (e.g. urea, DAP), oversowing with legumes, weed / pest / disease control.

  • Illustrative figure (Fig. 5.1) shows typical grassland.

5.1.2 Crop Residues

  • Definition: non-grain portion left after harvest – straws, stovers, cobs, husks, chaff.

  • Nutritive traits: low crude protein (CP), energy & micronutrients; high fibre → low palatability & digestibility.

  • Improvement strategies:

    • Supplement with legumes, grains or other concentrates.

    • Physical (chopping) or chemical (e.g. 5\%–7\% urea) treatments.

  • Unsuitable for pigs & poultry.

5.1.3 Forage Crops

  • Cultivated plants harvested as feed (fresh or conserved). Two botanical groups: grasses & legumes.

  • Grasses (Rhodes, Sudan, Elephant): highest dry-matter yield per area; cheaper bulk; higher fibre.

  • Legumes (Alfalfa, Vetch, Sesbania): higher protein, vitamin, mineral → natural supplement to residues & pastures.

  • Nutritive value declines with maturity – harvest at correct stage.

  • Promoted as a profitable business opportunity in Ethiopia; possibilities for youth/women groups with government support (land, credit). Grass-legume mixtures maximise yield, quality & profit (sell green forage, hay, planting material).

5.1.4 Agro-industrial By-products

  • Derived from processing of cereals, oilseeds, sugar, breweries.

  • Generally richer in energy or protein than roughages; used mainly as supplements.

    • Flour-milling by-products: wheat/rice bran, middlings – palatable, laxative, good in thiamine & niacin, fair CP & energy.

    • Oilseed cakes/meals: soybean, noug, cotton, peanut, groundnut – high CP, minerals.

    • Molasses: sugar-industry residue; \approx54\% TDN, \approx3\% CP; flavour enhancer & dust settler.

    • Brewery by-products: spent grain (high fibre & CP), spent yeast (cheap protein & B-complex vitamins).

  • Key terms:

    • Bran = outer kernel layers + some endosperm.

    • Cereal middlings = non-flour residue from milling.

    • Rice polish = fine powder removed during polishing.

    • Laxative feed = ferments quickly, stimulates bowel evacuation.

5.2 Classification of Feed Resources

  • Two mega-classes: Roughages vs. Concentrates (Fig. 5.5).

5.2.1 Roughages

  • Bulky, >18\% crude fibre (CF), <60\% total digestible nutrients (TDN).

  • Natural base for herbivores; comprise >50\% of typical livestock diets.

  • Forms:

    • Dry roughage: hay, straw, stover, husks, bagasse; 80–90\% DM.

    • Green/succulent roughage: fresh pasture (DM 10–30\%) or preserved as silage.

5.2.2 Concentrates

  • Dense in nutrients; <18\% CF, >60\% TDN; CP range 2\%–80\%.

  • Two functional groups:

    • Energy-rich: cereals, roots/tubers, molasses, bran; CP <18\%.

    • Protein-rich: >18\% CP; plant (oilseed cakes, soybean meal, cottonseed cake) or animal (fish, meat, blood meals).

5.3 Nutrient Requirements of Farm Animals

  • Nutrients = chemical substances required for maintenance, production & health. Six classes examined below (Table 5.1 synthesises sources & deficiency signs).

Water

  • >50\% of body weight. Functions: solvent, transport medium, temperature regulation, excretion. Fresh, clean supply essential; inadequacy lowers feed intake & productivity.

Carbohydrates

  • Primary energy source. From grains (wheat, maize, sorghum), molasses, forages, hay. Deficiency → reduced intake, weight gain, milk yield.

Fats (Lipids)

  • Concentrated energy, body insulation, carrier of fat-soluble vitamins. Present mainly in oilseed meals (up to 10\%). Lack → poor coat, infertility, vitamin-absorption issues.

Proteins

  • Amino-acid polymers; build tissues, enzymes, hormones. No body store, hence daily supply needed. Sources: legumes, oilseed cakes, fish/meat meals. Deficiency → stunting, poor quality product.

Minerals

  • Inorganic macro (Ca, P, Mg, K, Na) & micro (Cu, I, Fe, Mn, Zn) elements; structural & metabolic roles. Provided via bone meal, limestone, mineral lick, salt, agro-industrial residues. Imbalance → metabolic disorders/toxicities.

Vitamins

  • Organic cofactors: fat-soluble (A, D, E, K) vs. water-soluble (B-complex, C). Sourced from green fodder, vegetables, premixes. Inadequate supply → wide range of symptoms (rough coat, eye issues, scouring, pneumonia).

5.4 Feed Formulation Practices

  • Objective: combine ingredients in cost-effective proportions to meet nutrient specs for specific class, species & production stage.

  • Data needed: ingredient prices & availability, nutrient composition tables, animal nutrient requirements.

5.4.1 Types of Rations

  • Maintenance ration = minimum feed to keep body weight constant (≈ 50\% of total intake).

  • Production ration = nutrients supplied beyond maintenance for milk, meat, eggs, work.

5.4.2 Characteristics of a Good Ration

  • Meets dry-matter requirement relative to body weight.

  • Supplies digestible nutrients incl. minerals/vitamins.

  • Highly palatable & free from contaminants.

  • Adequate bulk for satiety & gut motility; digestibility enhanced by processing (grinding, rolling).

5.4.3 Methods of Balancing a Ration

  • Trial-and-error.

  • Pearson Square (most popular for two-ingredient CP or ME balancing).

  • Substitution method.

  • Computer software (linear programming, least-cost).

Pearson Square Steps (CP example)

  1. Draw square; centre = desired CP%.

  2. Upper-left = feed A CP%; lower-left = feed B CP%.

  3. Cross-subtract diagonally (ignore sign) to obtain proportion of each ingredient on right-hand side.

  4. Convert proportion to actual weight (divide by total of right-hand numbers × batch size).

Example: maize 9.5\% CP, soybean meal 42\% CP, target 16\% CP.

  • Parts maize = 42−16 = 26, parts SBM = 16−9.5 = 6.5.

  • Total parts = 32.5. For 100 kg ration: maize =\frac{26}{32.5}×100≈80\,kg, SBM ≈20\,kg.

Exercise (broiler starter 23\% CP, maize 10.5\%, SBM 37.4\%) left to the student.

5.5 Feed Conservation & Compound Feed Manufacturing

5.5.1 Feed Conservation

  • Rationale: bridge seasonal feed gaps; stabilise supply & animal productivity.

  • Two classical techniques: hay & silage.

Hay Making

  • Definition: forage cut during growth & preserved by drying (target moisture 15–20\% or DM 80–85\%).

  • Curing = moisture reduction via sun & wind.

  • Storage options: bales (square, rectangular, round) or tripod stacks (2–3 m high) – baling reduces volume & eases handling.

  • Advantages: low cost, simple equipment, easy transport, cash-crop potential.

  • Limitations: nutrient & palatability variability; weather-dependent; late harvest reduces quality.

Silage Making (Ensilage)

  • Anaerobic fermentation of wilted/chopped green forage sealed in silo/pit/bag.

  • Suitable crops: grasses at early heading, legumes at early bloom, maize/sorghum at dough stage.

  • Fermentation stages produce lactic acid, reducing pH ≤ 4 within 2–4 weeks.

  • Stepwise checklist (see Table 5.2): harvest ➜ wilt / chop ➜ optional additives (molasses \approx1\% DM, urea \approx1\%) ➜ rapid filling & compaction ➜ airtight sealing ➜ controlled opening & gradual feeding (ruminants only; avoid late-pregnant cows, young calves, sick animals).

  • Practical demonstration suggested in Activity 5.4; PPE & correct measurements stressed.

5.5.2 Compound Feed Manufacturing

  • Process flow (Fig. 5.9): raw-material reception & quality check ➜ storage ➜ weighing/batching ➜ grinding ➜ mixing ➜ optional pelleting, crumbling, cooling ➜ bagging / bulk dispatch ➜ laboratory QC.

  • Typical ingredients: cereals + agro-industrial by-products + salt, limestone, vitamin‐mineral premix (definition: micro-level additive blend for balanced micronutrient supply).

  • Quality control critical at every stage to ensure homogeneity, nutrient accuracy, bio-safety (mycotoxins, pathogens), pellet durability, label compliance.

Reflection, Connections & Implications

  • Economics: least-cost rationing directly influences farm profitability because feed dominates cost structure.

  • Environmental: efficient feed use reduces land pressure & methane per unit product; forage legume integration fixes N_{2} biologically, lowering fertiliser need.

  • Social: youth/women forage-production enterprises create rural employment & support national protein security.

  • Ethical: balanced feeding safeguards animal welfare (avoids hunger, malnutrition) and reduces over-feeding-induced metabolic disorders.

  • Policy: government support (credit, land allocation, training) can upscale improved forage & compound-feed industries, aligning with Ethiopia’s livestock development roadmap.

Self-Assessment Prompts

  • Brainstorming 5.1: Why is feed called the "driver" of animal performance? List local feed resources & discuss over/underfeeding consequences.

  • Brainstorming 5.2: Classify community feeds as roughage or concentrate; describe grass vs. legume characteristics.

  • Activity 5.2: Build a two-column table (roughage vs. concentrate) & sort 24 feedstuffs (maize grain, soybean meal, distillers’ grains, etc.).

  • Library/Internet Search (Activity 5.3): Complete a function-source grid for each nutrient class.

  • Exercise 5.1: Use Pearson Square to formulate 2000\,kg broiler starter 23\% CP with maize 10.5\% & SBM 37.4\%.

  • Field Demo (Activity 5.4): Perform silage making, document with photographs, report observations on fermentation aroma, temperature & colour.