AGRICULTURAL SCIENCE CLASS NOTES: ANIMAL NUTRITION

Class: Senior Secondary School 2 (SS 2) Subject: Agricultural Science Topic: Animal Nutrition

---

1. COMPREHENSIVE CORE CONCEPTS

Introduction to Animal Nutrition

Animal nutrition is the study of the food requirements of livestock and the processes by which they take in and utilize food substances for growth, repair, maintenance, and production. Just as humans need a balanced diet to stay healthy and productive, farm animals require a specific combination of nutrients to provide us with high-quality meat, milk, eggs, and wool.

The efficiency of any livestock enterprise depends largely on nutrition; it accounts for about 60-80% of the total cost of animal production. Therefore, understanding what to feed, how much to feed, and when to feed is a critical skill for any aspiring agriculturist.

Classification of Animal Feeds

Animal feeds are generally categorized based on their nutrient composition and physical nature.

A. Basal or Energy Feeds (Concentrates)

These are feeds high in energy (carbohydrates) but low in fiber (less than 18%) and protein. They are easily digestible.

• Examples: Maize (corn), cassava tubers, guinea corn, millet, and rice.
• Function: They provide the "fuel" or energy needed for the animal’s daily activities, such as walking, breathing, and maintaining body temperature. In poultry and pigs, basal feeds form the bulk of their diet.

B. Protein Supplements

These are feeds containing more than 20% protein. They are essential for building body tissues.

• Plant Sources: Groundnut cake (GNC), soybean meal, palm kernel cake (PKC), and cotton seed cake.
• Animal Sources: Fish meal, blood meal, and meat meal.
• Function: Proteins are the building blocks of the body. They are required for the growth of young animals, the repair of worn-out tissues, and the production of eggs, milk, and meat.

C. Roughages

Roughages are feeds high in fiber (more than 18%) and are often low in digestible nutrients. They are primarily fed to ruminants (cattle, sheep, and goats).

• Succulent Roughages: Fresh pasture grasses and legumes (e.g., Elephant grass, Centrosema).
• Dry Roughages: Hay (dried grass) and Straw (dried stalks of cereals).
• Silage: This is fermented green fodder stored in airtight conditions (silos). It is used to feed animals during the dry season.

D. Minerals and Vitamins

Though required in small quantities, these are vital for metabolic processes.

• Minerals: Calcium and Phosphorus for bone and eggshell formation; Iron for blood formation. Common sources include bone meal, oyster shells, and salt licks.
• Vitamins: Vitamin A (vision/growth), Vitamin B complex (metabolism), and Vitamin D (calcium absorption).

---

Nutrient Components and Their Functions

1. Carbohydrates: Provide energy. If an animal consumes more than it needs, the excess is stored as fat.
2. Proteins: Necessary for the production of hormones, enzymes, and the development of muscles.
3. Fats and Oils: Provide concentrated energy (2.25 times more than carbohydrates) and help in the absorption of fat-soluble vitamins (A, D, E, K).
4. Water: The most essential nutrient. It regulates body temperature, aids digestion, and transports nutrients within the body.

---

Types of Rations

A ration is the total amount of feed given to an animal within a 24-hour period.

• Maintenance Ration: The amount of feed given to an animal just to keep it alive and maintain its body weight without any gain or loss. It supports basic life functions like breathing and heartbeat.
• Production Ration: This is feed given over and above the maintenance ration to enable the animal to produce. This includes feed for growth (young animals), pregnancy (gestating animals), egg-laying (poultry), or milk production (dairy cows).
• Balanced Ration: A diet that contains all the essential nutrients in the correct proportions for a specific class of animal.

---

2. REAL-WORLD APPLICATIONS

Scenario 1: The Small-Scale Poultry Farmer

Imagine a family in your neighborhood raising 20 broilers for the December festivities. If they feed the birds only on crushed maize (a basal feed), the birds will look fat but will have very weak bones and poor muscle development because maize lacks sufficient protein and minerals. By understanding nutrition, the family can add "Fish Meal" or "Soybean Meal" to ensure the birds grow large and healthy for sale.

Scenario 2: Dry Season Survival for Cattle

In Northern Nigeria, the dry season leads to the drying up of pastures. Nomadic herders often travel long distances in search of green grass. A modern livestock farmer can apply the knowledge of animal nutrition by making Silage or Hay during the rainy season. This allows them to feed their cattle high-quality roughage at home throughout the dry season, preventing weight loss and death.

---

3. PRACTICAL APPLICATIONS (STEP-BY-STEP GUIDES)

How to Identify Quality Feed Ingredients

To ensure animals are well-fed, a farmer must be able to judge the quality of feed ingredients.

1. Visual Inspection: Maize should be free from mold (which contains deadly aflatoxins) and weevil holes.
2. Smell Test: Fish meal should smell like dried fish; a rancid or "spoilt" smell indicates the oils have gone bad, which can make animals sick.
3. Texture: Bone meal or oyster shell should be gritty, indicating high mineral content, and not mixed with sand.

Formulation of a Simple "Kitchen-Waste" Supplement for Goats

If you have goats at home, you can improve their nutrition using these steps:

1. Collect: Dry cassava peels, plantain peels, and bean husks.
2. Dry: Ensure all peels are thoroughly sun-dried to remove moisture and certain toxins (like cyanide in cassava).
3. Grind: Break them into smaller pieces.
4. Mix: Mix 3 parts cassava peels (Energy) with 1 part bean husks (Protein).
5. Serve: Provide this as a "production ration" in the evening when the goats return from grazing.

---

4. SUGGESTED HOME PROJECTS (PROJECT-BASED LEARNING)

Project: The Mini-Silage Experiment

Objective: To understand the process of fermentation and preservation of animal feed.

• Materials Needed:
  • Freshly cut grass or maize stalks.
  • A large, thick plastic bag (like a heavy-duty trash bag).
  • A small amount of molasses or sugar water.
  • String or twine.
• Procedure:
  1. Chop the fresh grass/maize stalks into small pieces (about 2-3 cm).
  2. Sprinkle a little sugar water over the chopped grass (this helps the "good" bacteria grow).
  3. Pack the grass into the plastic bag. Crucial Step: Press it down very hard to squeeze out all the air.
  4. Tie the bag tightly so no air can get in.
  5. Store it in a cool, dark place for 3 weeks.
• Observation: After 3 weeks, open the bag. If it smells slightly sweet/sour (like pickles) and is yellow-green, you have successfully made silage! If it smells rotten and is black, air got in, and it failed.

---

5. LIFE SKILLS INTEGRATION

Career Connections

• Animal Nutritionist: Experts who work for feed mills or government agencies to formulate diets for different species.
• Feed Mill Entrepreneur: You can start a business processing local ingredients (like PKC or Maize) into bagged feeds for sale.
• Livestock Manager: Ensuring the health and profitability of a farm through precise feeding.

Daily Life Skills

• Critical Thinking: Learning to analyze the "cost vs. benefit" of different feed types. Is it cheaper to buy expensive feed that makes birds grow in 6 weeks, or cheap feed that takes 12 weeks?
• Resourcefulness: Using "waste" products like corn bran or rice husks to create valuable animal feed, reducing environmental waste.

---

6. ASSESSMENT THROUGH APPLICATION

1. Feed Label Analysis: Find a tag from a commercial feed bag (Poultry Mash or Pig Starter). Identify the percentage of Crude Protein and Crude Fiber. Based on these numbers, categorize the feed (is it a concentrate or a roughage?).
2. The "Sick Animal" Case Study: A goat is walking with difficulty, its bones appear brittle, and it is eating its own bedding. Which nutrient is likely missing? Suggest two local ingredients you could feed the goat to help it.
3. Ration Design: If you are given Maize, Fish Meal, and Bone Meal, explain how you would vary the proportions for:
   • A young, rapidly growing chick.
   • An adult hen that is only being kept as a pet (maintenance).

---

7. STUDENT REFLECTION QUESTIONS

1. If you were a nomadic herder, how would your life change if you learned how to preserve hay and silage?
2. Why do you think humans eat meat and eggs? How is the nutrition of the animal connected to the nutrition of the person who eats the animal?
3. Look around your community. What "waste" materials from food processing (e.g., orange peels, corn husks, bean pods) are being thrown away that could be converted into animal feed?
4. Why is water often called the "forgotten nutrient"? What happens to a hen's egg production if she goes without water for 24 hours?