Nutrition Requirements for Growth, Maintenance and Production, Balanced Rations | Animal Husbandry & Veterinary Science Optional for UPSC PDF Download

Growth

• Growth is a natural phase in an animal's life characterized by an increase in size.
• There are two main approaches to understanding the relationship between nutrition and growth.
• The first approach focuses on finding diets that result in high-quality carcasses.
• The second approach involves analyzing the carcasses of animals that have been fed specific diets to achieve a desired end product.
• Understanding growth in terms of carcass composition is essential.

Energy Requirements During the Growth Period:

• The energy requirements for growth include basal metabolism, the energy content of new tissue, the heat increment of feeding, and energy needed for basic muscular activities.
• Basal metabolism is the energy needed to maintain basic metabolic functions and a constant body temperature.
• The energy content of new tissue can be determined using various techniques such as carbon and nitrogen balances or slaughter methods.
• The heat increment of feeding varies based on the type of diet consumed.
• Energy needed for physical activity and overcoming adverse conditions is variable and depends on the species.

Protein Requirements for Growth:

• Growth involves the sequential increase in the size of different organs in the body.
• The protein requirements for growth can be determined through various methods tailored to specific growth standards.
• Three main methods can help establish protein requirements for a particular growth standard within a species.

Biochemical Aspects of Dietary Protein

Consideration of Biological Value in Protein Assessment

• When evaluating different proteins, it is crucial to account for their biological value. This value determines the efficiency of protein utilization by the body for tissue formation rather than energy production. For instance, in a study with calves weighing around 200 kg, it was observed that a 1 kg supplement with 20% protein content resulted in higher nitrogen retention compared to a 0.5 kg supplement with 40% protein content, even though the former provided more energy.

Assessment Through Slaughter Techniques

• Another method involves measuring protein accumulation in the body and calculating nitrogen balances. In these assessments, protein is assigned a biological value of 100, indicating its importance in maintaining the body's growth and functions. For example, a boar weighing 250 kg requires approximately 45 g of protein with a biological value of 100 daily for basal metabolic needs.

Exploration of Amino Acid Requirements

• The third approach focuses on studying the essential amino acid requirements for different age groups and conditions in growing animals. This investigation often involves using purified proteins or amino acids to determine precise nutritional needs. While this method can be costly, it provides valuable insights into the protein requirements for optimal growth and development.

• Protein energy for growth varies with the age of the animal.
• Estimates show protein energy as a percentage of total digestible energy for growth.
• Physiological age 15 to 20 weeks
• Physiological age 20 to 30 weeks
• Physiological age 15-12 weeks
• Physiological age 12-10 weeks
• Physiological age 15-13 weeks
• Physiological age 13-11 weeks
• Physiological age 20-16 weeks
• Physiological age 16-13 weeks
• Physiological age 22-18 weeks
• Physiological age 18-14 weeks
• Protein energy requirements for various animals such as Cows, Horses, Pigs, Sheep, Dogs, Rabbits, Chickens, and Turkeys.

• There are about 20 amino acids considered essential for growth.
• The physiological requirements for growth include both essential and non-essential amino acids.
• A diet containing milk provides essential amino acids for growth.
• Weaning pigs require protein and ammonium citrate equivalent to a certain percentage of protein.

• Milk fat constitutes a significant portion of the energy in mammalian milk.
• Herbivores require lower fat content compared to omnivores and carnivores.
• The ideal fat content in food for pups ranges between 8% to 10% by weight.

• Young mammals and birds have limited ability to digest crude fiber.
• Feeds with more than 2% to 4% crude fiber hinder high growth rates.
• In herbivores during mid-growth, there can be a slight increase in crude fiber content.

• Vitamin requirements vary based on species, diet, and environmental factors.
• Herbivores and non-ruminants have different vitamin needs compared to ruminants.
• Inorganic elements such as Calcium, Phosphorus, Magnesium, Sodium, Iodine, Copper, Cobalt, and Molybdenum are essential for growth.
• Mineral supplements are necessary to fulfill the inorganic element requirements.

• Poultry and pigs often require additional nutrients beyond compounded feed.
• Antibiotics and growth additives are commonly included in the diet of poultry and pigs.
• Colostrum is essential for calves during the neonatal period for proper growth.
• Proper monitoring of rumen flora in calves enhances digestion efficiency.

• Special attention should be given to breeding stock in livestock.
• Mammalian females require adequate energy, protein, calcium, and phosphorus for lactation.
• A less fibrous and more concentrated ration may be necessary to meet increased nutritional demands.

Maintenance of Energy in Fasted Animals

• A well-nourished but not overweight animal, after fasting for 24 hours, expends no energy in:
  (i) Muscular activities like standing, walking
  (ii) Heat production as would be required in a cold environment
  (iii) Sweating or increased pulmonary ventilation needed in a hot environment
  (iv) Muscular movements and osmotic processes of the digestive system for food digestion
• In omnivorous and carnivorous species, and to a lesser extent in mature ruminants, basal metabolism continues during starvation. The duration of this metabolic activity depends on the previous diet.
• Basal metabolism refers to the energy required for maintaining muscular tone, supporting the heart, kidneys, brain, and other vital organs' functions.
• Basal metabolism is essential for basic bodily functions even when an animal is at rest.

• Animals need protein for maintenance, but the 100% increase in energy required for maintenance can be met efficiently by cheaper fat or carbohydrates instead of expensive protein.
• Animal tissue protein has a biological value of 100, making the apparent maintenance cost around 12.5 mg of protein per 2 calories of total maintenance energy.
• For example, a 250 kg boar needs approximately 50 grams of protein per day, which varies based on the animal's size.

• The biological value of dietary or microbially synthesized protein
• Endogenous urinary nitrogen excretion
• The fiber content of the food supplied

• Inorganic Elements: Calcium and phosphorus needs are about 0.25% to 0.3% of the weight of total digestible nutrients. Cobalt, iron, manganese, and zinc are required at specific rates. Vitamins A and D are also essential at specified rates based on the animal's weight.

Nutrients for Production

• Lactational requirements for nutrients are crucial for milk, meat, and work production in animals.
• Energy requirements for milk production are determined by the calorific value of the milk produced and its composition.

Equation for Calculating Energy Value of Milk:

• W(b) = 0.45 * 16F, where W is the weight of milk, and F is the amount of fat it contains.
• Various methods like the factorial method can be used to calculate total daily energy requirements for lactating cows based on specific constants.

• Cows require a specific amount of energy to produce milk efficiently. For instance, to produce one pound of standard milk, cows need around 610 calories of digestible energy.
• The gross efficiency of milk production, which relates the energy of milk secreted to the amount of feed required, increases with higher milk yield. It is approximately 56% for high-yielding cows, 45% for good yielders, and 28% for lower yielders.

Carbohydrate and Lipid Requirements for Lactation

• Carbohydrates are essential for milk production due to their economic and physiological benefits. They are the primary source of energy for milk production in cows.
• Regarding lipids, milk fats primarily consist of glycerides. Adjusting the fat content in cow rations can impact milk fat percentage.

Inorganic Elements in Milk Production

• The lactating animal's requirement for inorganic elements is directly related to the amount of milk produced. Deficiencies in these elements can lead to negative health impacts.
• Essential inorganic elements like sodium, potassium, chlorine, calcium, and phosphorus play crucial roles in milk composition and cow health.

Ration Construction Process

Matching Nutritional Requirements:

• The aim is to align qualitative and quantitative nutritional needs of animals.

Steps Involved:

• Calculation
• Selection, weighing, and potentially grinding of ingredients
• Mixing in two stages with vitamin or inorganic supplements
• Measuring out estimated amounts for a specific duration
• Placing the ration into food troughs

Considerations for Livestock Rations:

• Rations should be suitable for the animal species and conditions
• Must be palatable and meet requirements for dry matter, energy, protein, fat, vitamins, and minerals
• Palatability is crucial for consumption

Feed Variety for Herbivores:

• Coarse food for maintenance, concentrated food for production (e.g., milk or work)
• Balance needed to avoid underfeeding high-yielders

Protein/Energy Balance:

• Most production rations require specific protein to energy ratios
• Blending different food types can achieve the desired balance

Calculation Details:

• Starting from dry matter, considering energy, fat, proteins, vitamins, and inorganic elements
• Complex mixtures sometimes require careful balancing of ingredients

Mixture Computation for Milk Production:

• Energy and protein requirements for milk production
• Blending grains like sorghum, corn to achieve the right protein/energy ratio

Nutrient Analysis:

• Understanding nutrient composition for effective ration construction
• Calculation and examination of nutrient content for balanced rations

Understanding Balanced Ration for Milch Cow

• Ration Balancing: When creating a ration for a milch cow, it is crucial to ensure it is "balanced." This balance is key to meeting the cow's nutritional needs effectively.
• Importance of Net Energy: The net energy of the feed in the ration is essential and depends on factors such as digestible nutrients, crude fiber percentage, protein content, and blending with other foods.
• Role of Nutrients: A balanced ration should be evaluated based on the absorbed nutrients it provides. These absorbed nutrients are crucial for the cow's health and productivity.

Evaluating a Balanced Ration:

• Vitamins and Minerals: The addition of vitamins and minerals in a ration can impact the voluntary intake, palatability, digestibility, and nutrient metabolism of the food.
• Net Availability of Energy: Experimentally balanced rations are said to maximize the net availability of metabolizable energy, as suggested by Mitchell's postulate.

Empirical Formulation of Balanced Ration:

• Customization: A balanced ration is not a one-size-fits-all solution and needs to be formulated empirically and experimentally to suit specific needs.
• Economic Viability: In addition to nutritional considerations, a balanced ration should also be economically viable for practical implementation.