Feeding to meet the genetic potential of poultry

There remains a gap between birds reaching their genetic potential and feeding practices in poultry production. However, with new feeding techniques, producers may be able to get more than they realize from their flocks.

The role of genetics in poultry production has become the backbone in improving growth and reproductive performance as well as increasing profitability. Over the past thirty years, genetic progress has accounted for 85 percent of the current and future status of the poultry industry. However, while genetics have given us more and more meat in less time, our nutrition program has not kept up.

 Feed the genes 

As poultry nutritionists, we need to continually keep ourselves up-to-date on the latest in feeding practices. We must provide the energy, the amino acid building blocks and the make-it-happen vitamins and minerals to reach the cell level. In addition, we need to utilize feed additives to ensure all these nutrients reach the bird at the cellular level. Some of these additives only work at the intestinal level, while others work for metabolism. If all of these nutritional applications don’t go as planned, the bird will lose performance, which will be observed at the field level.

Decreased weight gains, poor feed efficiency, carcass yield reductions and metabolic disorders can all be found in poor broiler nutrition. For layers, reduced egg production, low egg weight, poor eggshell strength and internal quality have been observed. Metabolic disorders, such as osteoporosis and fatty liver, among others, can also been seen in layers that have not been fed well nutritionally. In breeders, a plunge in egg production, fertility, hatchability and less number of chicks are common in poor diets. A lack of vitamins and trace minerals in breeder diets can also bring about a disaster in embryo development.

Attempts have been made with fairly good success to fill this genetic gap throughout the years. The basic idea has been to feed the animal according to its needs or where we want the animal needs to be (eg. performance, immune response). The idea now is to go one step further and “feed the genes.”

Meeting animal needs

Many years ago, diets were formulated using the productive energy system. However, researchers concluded that metabolizable energy would be a more appropriate system to express energy availability and requirement. Today, as a step beyond, net energy system has been considered in some parts of the world. Likewise, years ago, crude protein and a total amino acid system were used to calculate poultry diets. University researchers and nutritionists then realized that this was not the most appropriate method to be used and thus developed the ideal protein system, which is based on available amino acids. Naturally, the advent of commercially available essential synthetic amino acids has made the whole story easier. The idea is to give no more and no less amino acids than the animal needs.

Energy and protein need to be well balanced, but this is only part of the nutritional story. More available and efficient vitamin metabolites, such as those derived from vitamin D, have allowed for better calcium and phosphorus absorption. More recently, in terms of nutrition history, new technology has been developed in minerals as well. Organic minerals are more bioavailable and can fulfill the metabolic requirements more efficiently. This increase in efficiency allows for lower inclusion levels in the diet compared to the traditional inorganic mineral NRC requirements. Consequently, by feeding organic minerals to animals, an enhancement in metabolism may be observed.

For example, selenium-yeast is used worldwide to improve poultry performance and to enrich eggs and meat. Researchers have also observed that inorganic and organic selenium interact with the genome in different ways. For instance, birds fed selenium-yeast have their genes for antioxidant protection expressed in a more efficient way. The complete replacement of inorganic with organic minerals also supports a reduction in environmental pollution, without sacrificing poultry performance. Organic minerals show less chance of toxicity and no interaction with phytic acid, as this can happen with inorganic minerals.

New feeding applications

While all of these improvements in feeding energy, protein and minerals have helped push the poultry industry farther ahead nutritionally, researchers are finding new feeding applications each year that can close the gap even further. Instead of feeding the birds what we think they should be given, new strategies have been developed to make the bird even more efficient with the nutrients it receives. It is not just what we feed, but when we feed that is important.

Studies have indicated that it is possible to imprint the genes in a very early age of the bird and turn it into a more efficient animal later. One way of doing this is through in ovo feeding. Basically that bird’s first meal can make the difference. We need to synchronize in ovo feeding when the embryo begins to imbibe amniotic fluid (Day 17-18 of embryo development).

Administration of highly digestible nutrients into the amnion of embryos can bring an improvement in chick quality, increased glycogen reserves, advanced gut development, superior skeletal health, advanced muscle growth, higher body weight gain, improved feed conversion and enhanced immune function. New technology utilizing a particular gene chip technique has revealed important information about in ovo feeding. Using this particular gene chip technique, it was observed that close to 30 percent of genes are expressed differently over time by in ovo feeding (Oliveira et. al. 2008). This technique may soon be available for the commercial poultry industry.

Closing the gap

Monitoring nutrient intake post-hatch is another way to imprint genes at a very early age. Production traits, such as a tolerance to immunological environmental or oxidative stress, and energy and mineral utilization, can be imprinted by adaptive conditioning of gene expression. During the first 24 hours post-hatch, the small intestine, liver and pancreas develop at a faster rate than body weight. The chick needs to be fed as soon as possible to provide substrate for gastrointestinal development, weight gain and immune system development. High quality ingredients, mannan-based oligosaccharides, nucleotide-rich ingredients, mycotoxin adsorbents and organic minerals should be part of any poultry diet, especially pre-starters.

While it’s a known fact that our nutrition has not kept pace with the advancements in genetic selection in the poultry industry, we are taking major strides in closing that gap. Expression of genetic potential can be programmed by breeder, embryo and chick nutrition. Epigenetics, in ovo nutrition and post-hatch dietary conditioning can enhance production efficiency to benefit poultry producers while improving meat quality and safety of poultry products for our consumers.