Nutritional terms and their definitions. Nutritional aspect of carbohydrates, protein and fats

I. Nutritional Terms and Their Definitions

1. Nutrition
   • The process by which animals consume, digest, absorb, and utilize nutrients for maintenance, growth, reproduction, and overall health.
2. Nutrient
   • Any chemical substance that provides energy or supports growth, reproduction, and the maintenance of life.
3. Macronutrients
   • Nutrients required in large amounts, including carbohydrates, proteins, and fats, which provide energy and are essential for structural and metabolic functions.
4. Micronutrients
   • Nutrients needed in smaller amounts, including vitamins and minerals, essential for enzymatic reactions, immune function, and overall well-being.
5. 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.
6. 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).
7. Metabolism
   • The sum of all biochemical processes occurring in the body, including catabolism (breakdown of molecules) and anabolism (synthesis of molecules).
8. Basal Metabolic Rate (BMR)
   • The minimum energy requirement to sustain life processes at rest, in a thermoneutral environment, and in a post-absorptive state.
9. Feed Efficiency
   • A measure of the animal’s ability to convert feed into body mass, often expressed as feed conversion ratio (FCR).
10. Digestible Energy (DE)
    • The portion of energy in the feed that is absorbed from the gastrointestinal tract.
11. Protein Quality
    • A measure of how well a dietary protein provides essential amino acids to meet the animal’s requirements.
12. Lipid Profile
    • The composition of fatty acids and cholesterol in the diet, influencing energy provision and cell membrane integrity.

II. Nutritional Aspect of Carbohydrates

1. Overview
   • Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen, primarily functioning as an energy source.
2. 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).
3. 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.
4. Digestibility
   • Starch and sugars are highly digestible in monogastric animals.
   • Cellulose and hemicellulose require microbial fermentation in the rumen of ruminants.
5. Deficiency
   • Leads to reduced energy availability, weight loss, and poor production performance.
6. Excess
   • Can result in obesity, metabolic disorders, and digestive disturbances like acidosis in ruminants.

III. Nutritional Aspect of Proteins

1. Overview
   • Proteins are polymers of amino acids essential for growth, repair, and maintenance of tissues.
2. 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).
3. Functions
   • Building blocks of muscles, enzymes, hormones, and antibodies.
   • Regulate physiological functions, such as transport of oxygen (hemoglobin) and immune response.
4. Essential Amino Acids
   • Must be supplied in the diet as they cannot be synthesized by the body (e.g., lysine, methionine, tryptophan).
5. Protein Quality
   • Measured by biological value (BV) and protein efficiency ratio (PER). Animal proteins generally have higher BV compared to plant proteins.
6. Deficiency
   • Symptoms include stunted growth, muscle wasting, poor reproductive performance, and reduced immunity.
7. Excess
   • Results in inefficient use of protein as an energy source, increased ammonia production, and kidney strain.
8. 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

1. Overview
   • Fats (lipids) are energy-dense macronutrients composed of glycerol and fatty acids.
2. 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).
3. 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).
4. 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.
5. Deficiency
   • Leads to poor growth, skin disorders, reproductive issues, and impaired immune function.
6. Excess
   • Can result in obesity, cardiovascular problems, and liver dysfunction.
7. Ruminant Considerations
   • Ruminants rely on microbial biohydrogenation to modify dietary unsaturated fats into saturated fats, affecting milk composition.

V. Comparative Nutritional Roles