Practical insights into poultry nutrition

Providing poultry with the proper building blocks for growth will help producers attain maximum performance.

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Quoting Liebig’s law, Malala said that growth is controlled not by the total amount of resources available, but by the scarcest resource, and so protein synthesis may be limited due to the lack of a single essential amino acid. (Mark Clements)
Quoting Liebig’s law, Malala said that growth is controlled not by the total amount of resources available, but by the scarcest resource, and so protein synthesis may be limited due to the lack of a single essential amino acid. (Mark Clements)

How chickens access the building blocks for growth and egg production and how the gut responds to them was examined by Douglas Malala, business manager of animal nutrition, and John Owaga, technical services manager, both with Evonik in East Africa. The two spoke at WATT Global Media’s Practical Insights into Poultry Nutrition at Poultry Africa 2019, held in Kigali, Rwanda.

Malala, looking at the role of protein and amino acids, noted that where crude protein is concerned, producers are often encouraged to believe that the higher the crude protein content of a poultry diet the better, but, he continued, this is not the case. Poultry does not have a requirement for crude protein; they need amino acids.

Amino acids can be viewed as the building blocks of a house, he said, and producers should pay more attention to these building blocks, rather than to the house itself.

These blocks can be divided into two groups. Essential amino acids, or those that cannot be synthesized by the bird in sufficient quantities for optimum performance, must be supplied in the feed. Then there are non-essential amino acids, that do not have to be provided in the diet and that the body can synthesize. However, all amino acids are important and must be present in sufficient quantities for the bird to grow.

It is amino acids that are used to build protein and, while some may be more important than others, if even one is missing then protein synthesis will stop.

Each amino acid has its role

This can become particularly evident when a farmer may substitute one amino acid for another, due to price increases for example, with the result that chicks may be stunted or eggs are smaller.

Various repetitions of amino acids form the polypeptide chains that make up proteins, and should there be an insufficient supply of even one component protein synthesis will stop. Any non-incorporated amino acids will simply be wasted.

Using the example of a wooden bucket made up of staves with varying lengths, he pointed out that the bucket could only be filled with water to the height of the lowest stave; all the staves, or in the case of protein production amino acids, must be present if the bucket is to be filled to the top or the bird is to meet its maximum potential.  

Amino acid inclusion in diets must be balanced. A failure to do so will not only directly compromise performance, but also the bird will need to expend energy in excreting what is not used, indirectly compromising growth or production. Without the correct balance birds will never perform in the way that they are supposed to.

Additionally, it is important to look at digestible amino acids. This is affected by the raw materials used in diets, the breed of birds being reared, anti-nutritional factors and feed processing techniques, yet producing diets based on digestible amino acids will help to achieve a more precise formulation. Soya, for example, will not have the same nutritional value as rapeseed, while processing method may increase anti-nutritional factors.

Amino acids are essential nutrients for healthy birds and efficient production, and their inclusion not only lowers requirements for crude protein and saves money but also helps to reduce pollution as fewer nutrients are wasted, Malala concluded.

Gut health

No matter how well a feed may be balanced, a bird must have a healthy gut to gain maximum benefit from it, and this was examined by John Owaga.

The gastrointestinal tract (GIT), he explained, has an enormous surface that is constantly exposed to a wide variety of potential threats, acting as a selective barrier to nutrient absorption, while preventing pathogen entrance.

Seventy percent of all immune cells reside in the intestine which is densely populated with micro-organisms that closely and intensively interact with the host. This gut microbiome is an essential part of the intestinal ecosystem, contributing to the well-being of the host in a variety of ways, especially where nutrition and disease resistance are concerned.

The first few weeks of life are crucial for gut development and mucin production, which are linked to intestinal bacterial populations.  In chickens, microbiota colonization occurs immediately after hatch, and both microbiota from the eggshell and the environment form the first inoculum. 

The characteristics of this first inoculum are highly important, as they impact further colonization and the functional development of intestinal tissue in terms of barrier function and immune programming.  

There are three important areas that affect the gut health of the chicken, said Owaga: diet, environment and the gut microbiome itself.

Any dietary components that escape host digestion and absorption will serve as the substrate for the intestinal bacteria growth. When, for example, protein is oversupplied it will not all be digested, reaching the hind gut where it will support the growth of pathogenic bacteria, impacting gut health.

Type of ingredient used in feed will also influence the microbiota. For example, wheat-, barley- or rye-based diets tend to favor Clostridium pefringens growth which is associated with necrotic enteritis. Protein source also affects gut health, with fishmeal and meat and bone meal, for example, inherently high in bacteria.  When animal fat is added to feed, for example lard or tallow, there is a higher chance of increasing C pefringens, as compared to when using vegetable fat.

Environment will also play a role in gut health, including factors such as flock density, ventilation, pathogen load, and biosecurity.

John-Owaga

Owaga explained that any dietary ingredients that are not digested will reach the hind gut, where they may adversely affect the local bacterial population and negatively affect gut health. (Mark Clements)

 

 

 

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