17 Mar 2022
Poultry diet formulation must always consider the inclusion of certain key nutrients. When formulating diets for poultry, the energy level is usually selected as a starting point. An appropriate energy level is one that is likely to result in the lowest feed cost per unit of product (weight gain or eggs). The cost of feed per unit of product, in turn, is determined by the cost per unit weight of the diet and the amount of diet required to produce a unit of product.
The energy level of diets is often used as the basis for establishing most nutrient concentrations in a serving.
This approach to diet formulation in poultry farming is based on the concept that poultry tend to eat to meet their energy needs, assuming that the diet is adequate in essential nutrients.
However, such an assumption should be made with caution and with an understanding of its possible limitations.
For example, if a diet is deficient in some nutrient, daily food consumption may decrease relative to the severity of the deficiency. An exception may occur with an amino acid deficiency, whereby a marginal deficiency may result in a small increase in feed consumption.
Besides energy and nutrient balance, there are other factors that affect food intake like:
The latter can have a considerable impact on pultry’s feed consumption, especially in adult birds. This is due to the fact that feed consumption decreases as environmental temperature rises.
At temperatures above 30°C, the decrease in feed consumption can be 2.5 to 4g for every 1°C increase.
Carbohydrates
Dietary carbohydrates are important sources of energy for poultry. Cereals such as corn, sorghum, wheat and barley contribute most of the carbohydrates to the birds’ diet. Most of these carbohydrates are found as starch, which poultry can digest easily.
Other carbohydrates are found in varying concentrations in cereals and protein supplements. These include polysaccharides such as cellulose, hemicellulose, pentosans, and oligosaccharides (such as stachyose and raffinose), all of which are poorly digested by poultry.
Therefore, these types of carbohydrates have a minor contribution in regards to meeting the energy needs of poultry. Sometimes even having negative effects on digestive processes when they are present in high concentrations within the diet.
Supplementation of diets containing rye or barley with appropriate supplemental enzyme preparations improves nutrient utilization and growth of young poultry.
Proteins and aminoacids
[register]Protein requirements are actually requirements of the amino acids contained in dietary protein. Poultry uses amino acids obtained from proteins to fulfill various functions:
Due to the fact that body proteins are in a dynamic state, involving continous synthesis and degradation, an adequate intake of amino acids is required in diets. If dietary protein (amino acids) is inadequate, growth or productivity reduce or compeltely cease. Animals enter a state of catabolism where they degrade proteins from less vital body tissues to maintain vital tissue functions.
There are 22 amino acids in the body’s proteins and they are all physiologically essential. Nutritionally, these amino acids can be divided into two categories:
If the diet does not provide non-essential amino acids, poultry must synthesize them. The presence of adequate amounts of non-essential amino acids in diets reduces the need to synthesize them from essential amino acids.
Therefore, indicating the dietary requirements of essential amino acids is an appropriate way to ensure that all physiollogically necessary amino acids are provided.
Variations in requirements
Protein and amino acid requirements vary considerably depending on the productive state of the bird. Whether it is the growth rate or egg production. For example
The body size, growth rate and egg production of poultry are determined by their genetics. Amino acid requirements, therefore, also differ between types, breeds and strains of poultry. Genetic differences in amino acid requirements can occur due to differences in the efficiency of digestion, nutrient absorption, and metabolism of absorbed nutrients.
Although dietary requirements for amino acids and proteins are usually expressed as percentages of the diet, the quantitative needs of poultry must be met with a balanced source for maximum productivity.
Percentage requirements for proteins and amino acids should increase in warmer environments and decrease in colder environments, according to expected differences in feed intake.
The protein and amino acid concentrations presented here as requirements are intended to support peak growth and production.
However, achieving maximum growth and production may not always guarantee maximum economic returns, especially when the prices of protein sources are high. If decreased yield can be tolerated, dietary amino acid concentrations can consequently be reduced somewhat to maximize economic benefits.
Fats
Usually, fat is added to the diets of meat poultry to increase the total energy concentration and, in turn, improve productivity and feed efficiency.
Lipid accumulation is most evident in adipose tissue; however, cell multiplication also requires a number of lipids to form associated membranes. These two uses can occur simultaneously; however, the scope of each can vary considerably.
Sources
Fat can come from different sources. Some common sources are: from restaurants, extraction from slaughterhouses, and waste from vegetable oil refining.
The total fatty acids contributed by all lipid categories, the proportion found in free form and the types of fatty acids present, provide information related to the expected digestibility. As well as indicating the way in which fat can be subsequently used. The length of the fatty acid chain, the degree of unsaturation and the nature of esterification influence intestinal absorption.
All dietary fats should be stabilized with an antioxidant to preserve unsaturated fatty acids and should be routinely monitored for the possible presence of undesirable residues such as insolubles, chlorinated and unsaponifiable hydrocarbons, and peroxides.
Fat mix
When animal sebum is added to feed at a low level, it is beneficial to mix it with a small amount of vegetable oil. The metabolizable energy value resulting from these mixtures is greater than what can be explained from the arithmetic combination. Synergism in the absorption of saturated fatty acids related to the added amounts of unsaturated fatty acids is suspected to be responsible for such effect.
The properties of animal tallow can also be enhanced by the presence of food ingredients containing unsaturated fatty acids. Corn is particularly advantageous in this respect because its fatty acids are mostly unsaturated and normally make up a large portion of diets.
Source: Extract from Nutrient Requirements of Poultry, 9 edition, 1994
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