I. Nutritional Terms and Their Definitions
- Nutrition
- The process by which animals consume, digest, absorb, and utilize nutrients for maintenance, growth, reproduction, and overall health.
- Nutrient
- Any chemical substance that provides energy or supports growth, reproduction, and the maintenance of life.
- Macronutrients
- Nutrients required in large amounts, including carbohydrates, proteins, and fats, which provide energy and are essential for structural and metabolic functions.
- Micronutrients
- Nutrients needed in smaller amounts, including vitamins and minerals, essential for enzymatic reactions, immune function, and overall well-being.
- Essential Nutrients
- Nutrients that cannot be synthesized by the body and must be obtained through the diet. Examples include essential amino acids, fatty acids, vitamins, and some minerals.
- Energy
- The capacity to perform work. Energy in animal nutrition is derived from the oxidation of carbohydrates, proteins, and fats, measured in kilocalories (kcal) or megajoules (MJ).
- Metabolism
- The sum of all biochemical processes occurring in the body, including catabolism (breakdown of molecules) and anabolism (synthesis of molecules).
- Basal Metabolic Rate (BMR)
- The minimum energy requirement to sustain life processes at rest, in a thermoneutral environment, and in a post-absorptive state.
- Feed Efficiency
- A measure of the animal’s ability to convert feed into body mass, often expressed as feed conversion ratio (FCR).
- Digestible Energy (DE)
- The portion of energy in the feed that is absorbed from the gastrointestinal tract.
- Protein Quality
- A measure of how well a dietary protein provides essential amino acids to meet the animal’s requirements.
- Lipid Profile
- The composition of fatty acids and cholesterol in the diet, influencing energy provision and cell membrane integrity.
II. Nutritional Aspect of Carbohydrates
- Overview
- Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen, primarily functioning as an energy source.
- Classification
- Monosaccharides: Simple sugars (e.g., glucose, fructose).
- Disaccharides: Two monosaccharides linked together (e.g., sucrose, lactose).
- Polysaccharides: Complex carbohydrates (e.g., starch, cellulose, glycogen).
- Functions
- Primary energy source for metabolic activities.
- Provide structural components in the form of cellulose in herbivores.
- Serve as precursors for other biomolecules like nucleotides and glycoproteins.
- Digestibility
- Starch and sugars are highly digestible in monogastric animals.
- Cellulose and hemicellulose require microbial fermentation in the rumen of ruminants.
- Deficiency
- Leads to reduced energy availability, weight loss, and poor production performance.
- Excess
- Can result in obesity, metabolic disorders, and digestive disturbances like acidosis in ruminants.
III. Nutritional Aspect of Proteins
- Overview
- Proteins are polymers of amino acids essential for growth, repair, and maintenance of tissues.
- Classification
- Based on amino acid composition: Complete (contain all essential amino acids) and Incomplete proteins.
- Based on source: Animal-based (e.g., meat, fish) and plant-based proteins (e.g., soybean meal).
- Functions
- Building blocks of muscles, enzymes, hormones, and antibodies.
- Regulate physiological functions, such as transport of oxygen (hemoglobin) and immune response.
- Essential Amino Acids
- Must be supplied in the diet as they cannot be synthesized by the body (e.g., lysine, methionine, tryptophan).
- Protein Quality
- Measured by biological value (BV) and protein efficiency ratio (PER). Animal proteins generally have higher BV compared to plant proteins.
- Deficiency
- Symptoms include stunted growth, muscle wasting, poor reproductive performance, and reduced immunity.
- Excess
- Results in inefficient use of protein as an energy source, increased ammonia production, and kidney strain.
- Ruminant Considerations
- Rumen microbes can synthesize protein from non-protein nitrogen (NPN) sources like urea, but excessive NPN can lead to toxicity.
IV. Nutritional Aspect of Fats
- Overview
- Fats (lipids) are energy-dense macronutrients composed of glycerol and fatty acids.
- Classification
- Saturated Fatty Acids: No double bonds; solid at room temperature (e.g., animal fat).
- Unsaturated Fatty Acids: One or more double bonds; liquid at room temperature (e.g., vegetable oils).
- Essential Fatty Acids: Required in the diet (e.g., linoleic acid, alpha-linolenic acid).
- Functions
- Primary energy reserve in the body.
- Insulation and protection of organs.
- Essential for cell membrane integrity and synthesis of bioactive molecules (e.g., prostaglandins).
- Digestion and Absorption
- Lipids are emulsified by bile salts and hydrolyzed by pancreatic lipase in the intestine.
- Absorbed fatty acids are either stored or utilized for energy.
- Deficiency
- Leads to poor growth, skin disorders, reproductive issues, and impaired immune function.
- Excess
- Can result in obesity, cardiovascular problems, and liver dysfunction.
- Ruminant Considerations
- Ruminants rely on microbial biohydrogenation to modify dietary unsaturated fats into saturated fats, affecting milk composition.
V. Comparative Nutritional Roles
Nutrient | Primary Role | Deficiency Effects | Excess Effects |
---|---|---|---|
Carbohydrates | Energy source | Weight loss, poor production | Obesity, digestive disturbances |
Proteins | Tissue building, enzymes, hormones | Growth retardation, low immunity | Kidney strain, ammonia toxicity |
Fats | Energy reserve, cell membranes | Poor growth, skin issues, infertility | Obesity, metabolic disorders |