Nutritional Factors: Affecting Egg Quality and Hatchability in Poultry

Pashu Sandesh, 12 July 2023

Anisha¹, Monika Karnani², Sheela Choudhary³ and Manju²

Department of Animal Nutrition

Post Graduate Institute of Veterinary Education and Research (PGIVER), Jaipur

¹ PhD Scholar, Department of Animal Nutrition, PGIVER, Jaipur

² Assistant Professor, Department of Animal Nutrition, PGIVER, Jaipur

³ professor & Head, Department of Animal Nutrition, PGIVER, Jaipur

⁴Assistant Professor, Department of Animal Nutrition, PGIVER, Jaipur

Introduction:

Nowadays Consumers are more and more interested in the health aspects of their food. Therefore, it is essential for egg production to be aware of factors affecting egg quality in poultry. The egg's internal quality depends on different parameters that are related to the yolk and albumin. Several nutrients have an effect on egg quality as well as hatchability. So the adequate supply of these nutrients may have a beneficial effect on egg quality and hatchability. 

1. Nutritional factors affecting egg quality

Important components of egg quality are eggshell quality, nutritional egg composition, egg size, vitelline membrane strength etc. Egg quality is not only the feed composition but the way birds are fed. Feeding and management of poultry have a great impact on egg quality. 

Egg Shell Quality  

Many nutritional factors have a direct and indirect effect on eggshell quality. Direct factors have a strong effect on eggshell quality and indirect factors have an effect on egg size and indirectly on eggshell quality. 

Direct effect 

Calcium deficiency will lead to weaker eggshells with a decrease in eggshell weight and eggshell strength. Phosphorus is an important nutrient for eggshell quality. Phosphorus has a strong effect on bone strength. If calcium provides from the feed is not enough to support the calcium requirement for the eggshell formation, calcium is mobilized from the bone. But this calcium mobilisation is linked with a phosphorus release in the blood. A high phosphorus level in the blood inhibits calcium mobilisation from the bones. Vitamin D is necessary for calcium metabolism. Vitamin D deficiency leads to poor eggshell quality, mainly due to a decrease in eggshell weight. Trace elements like zinc, copper and manganese have been shown to have an effect on eggshell quality. 

Indirect effect 

Indirect effects could be through egg size management or liver protection effect. Smaller eggs have better eggshell strength. Diets rich in fat, in unsaturated fatty acids like linoleic acid, with high levels of protein and amino acids, push up the egg size. The liver is the key organ for egg production. Laying hens suffering from fatty liver produced fewer eggs and eggs with a bad eggshell quality. All the nutritional factors which help to protect the liver, like choline, folic acid and vitamin B12 have also an indirect effect on eggshell quality by preventing the liver's ability to convert vitamin D. 

Cleanness of eggshell 

Eggshell cleanness depends on water consumption, manure structure, manure water holding capacity and interaction between each other. Most of these parameters are linked with nutrients. Soluble fibres, like xylan, β-glucan and pectic substances, increase water consumption. The use of enzymes (xylanase / β glucanase) has been shown to decrease the negative effect of soluble fibre by decreasing water consumption. 

Egg White Quality 

Egg white composition is strongly linked to the diets used. Riboflavin, folic acid, niacin, thiamine, pyridoxine, pantothenic acid, biotin and vitamin B₁₂ are well transferred into the egg white and their concentrations depend on feed concentration. Trace elements are also well transferred into the egg white. Egg white concentrations of iodine, selenium and copper are linked to the levels used in the feed. Blood spots are affected by mycotoxins contamination like ochratoxin, strong choline deficiency, vitamin A and vitamin K. 

Egg Yolk Quality 

Egg yolk composition strongly reflects feed composition. Egg yolk fatty acid profile is directly linked to the fatty acid profile of diets. Diets rich in omega-3 lead to egg yolks rich in omega-3 and omega-6 fatty acids. Fatty acids found in the egg yolk are linked to the feed fatty acid profile. Feed vitamin concentration affect also egg yolk vitamin composition. Compared to the egg white, where water-soluble vitamins are well transferred, egg yolk due to its composition, is mainly fat-soluble vitamins which are transferred like vitamin A, vitamin E and vitamin D. Good transfer rates have been shown for iodine, copper and selenium. Some differences have been observed according to the trace element source; organic forms have a better transfer than inorganic forms. Carotenoids bring colour to the egg yolk which is important for consumers, but modulate the anti-oxidant potential of the eggs too. 

Vitelline membrane 

A membrane is useful to separate white and yolk. A weak membrane leads to important economic losses because once the membrane is broken, egg yolk is polluting the egg white. Like the egg yolk, the vitelline membrane fatty acid profile depends on the feed fatty acid profile. The type of fat in the feed used affects fatty acids incorporated in the vitelline membrane. Elasticity and permeability of the membrane are then affected. Saturated fatty acid increases vitelline membrane permeability. Vitamin E increases vitelline membrane strength.

2. Effects of maternal nutrition on hatchability –

Normal embryonic growth and development depend on a complete supply of all required nutrients within the egg. Deficiency or large excess of nutritional elements makes embryo diseases prone, Creates defects and lethal stress. This supply of nutrients originates in the maternal diet and metabolism. It is further determined by the effectiveness of deposition into the egg. Excesses of certain nutrients or egg constituents may cause problems as serious as those from deficiencies. Here describe some of the known effects on hatchability and embryonic development of nutrient deficiencies, excesses, and interrelationships. 

VITAMINS

Vitamin A

In research, the effect of vitamin A on hatchability was found significantly increased, decreased and non-significant. Excess dietary vitamin A (> 10,000 IU/kg) can cause early embryonic mortality and decreased hatchability. Signs observed in vitamin A-deficient embryos include an increased incidence of malpositions, abnormal circulatory system development, and other problems. 

Biotin

Biotin has been shown to be necessary for normal embryonic development and hatchability. Increased biotin levels in broiler breeder diets appear to partially alleviate severe footpad problems in the progeny. Signs of biotin-deficient embryos include increased mortality peaks before 5 days or after 17 days, a chondrodystrophy or micromelia condition, shortened bones, and a “parrot beak”.

Riboflavin

One of the more common nutritional deficiencies affecting hatchability is that of riboflavin. Maximum hatchability was observed with 2.75 mg riboflavin/kg diet. Riboflavin-deficient embryos may show oedema, increased mortality at 9 to 14 days of incubation, clubbed down, haemorrhages, dwarfing, micromelia, and anaemia. Haemorrhages and clubbed down are the most common signs. 

Vitamin B₁₂

Vitamin B₁₂ is essential for normal hatchability. Excess levels of B₁₂ resulted in reduced deposition of riboflavin in the egg yolk. A vitamin B₁₂ deficiency was found to cause a moderate reduction of egg production in White Leghorns and a more severe reduction in Rhode Island Reds. Abnormalities include oedema around the eyes, poor leg muscle development, haemorrhages, dwarfing, shortened beak, and head between-thighs malposition.

Pantothenic Acid

A diet deficient in pantothenic acid results in decreased hatchability, and chicks with muscular incoordination, swollen hocks, and poor feathering. A synergistic relationship with vitamin B12 has been observed.

Thiamine 

Thiamine is very plentiful in cereal grains that are commonly used in poultry diets; therefore, a breeder flock deficiency is unlikely to occur unless unusual ingredients are utilized. A thiamine deficiency results in polyneuritis and embryonic mortality. 

Niacin

 Niacin is required by the embryo for normal development and hatchability. Excesses of nicotinamide have also caused embryonic mortality and loss of hatchability.

Folic Acid

The breeder hen has a higher requirement of dietary folic acid for hatchability than for egg production. In deficiency conditions, embryonic abnormalities include bent tibiotarsus, shortened bones, beak defects, and syndactylism. Most embryos appeared normal but died after pipping the air cell. 

Pyridoxine

Pyridoxine deficiency in hens resulted in immediate anorexia followed by reduced hatchability and the cessation of egg production. 

Vitamin K

Haemorrhages in the embryo or embryonic membranes have been described as the primary sign of deficiency. 

Vitamin D

A vitamin D deficiency results in late embryonic mortality, mostly on Days 18 and 19 in the chicken. In addition to causing late embryonic mortality, a cholecalciferol deficiency also causes beak deformities and inadequate skeletal formation. Excess levels of vitamin D have also been reported to reduce hatchability.

Vitamin E

 Symptoms in the vitamin E-deficient embryo include cloudy eye spots, blindness, abnormal vascular system and stunting. Vitamin E supplementation of breeder hen diets has been reported to result in increased immune responses in the progeny 

Vitamin Fortification

Fortification of eggs is possible for most vitamins through increased breeder diet levels. Egg levels respond rapidly to dietary increases of riboflavin, cholecalciferol, biotin, vitamin B12, pantothenic acid, and folacin, whereas vitamin A levels respond more slowly. 

MINERALS

Selenium

Decreased hatchability was found when feeding a selenium-deficient diet to poultry. Chicks that hatched were weak and had gizzard muscle myopathy, and many were prostrate with their legs extended backward and curved upward. Abnormalities due to excess selenium include dwarfing, short or missing lower beaks, and shortened bones of the legs and wings. 

Iodine

An iodine deficiency can cause decreased hatchability but naturally occurring deficiencies are rare. Excess dietary iodine will also cause hatchability problems, resulting in embryonic mortality, unhatched pips, and extended incubation periods. 

Manganese

A manganese deficiency results in reduced hatchability and embryonic abnormalities almost identical to those of biotin deficiencies. Ataxia in the form of a tetanic spasm of the opisthotonic type has been described in manganese-deficient embryos. The breeder hen may be able to tolerate a lack of manganese supplementation in the diet for several weeks with no adverse effects on hatchability.

Calcium

Calcium levels in breeder diets affect embryonic development primarily through eggshell quality. Poor shells due to calcium-deficient breeder diets and other causes result in excessive egg weight loss accompanied by increased 1st-week mortality, increased contamination, and embryos with stunted growth, poor bone development, and increased mortality at the end of incubation. 

Phosphorus

Phosphorus is necessary to support normal embryonic bone development and hatchability. Caged layers require 0.4% phosphorus for normal hatchability, whereas broiler breeders on the litter floor had normal hatchability with 0.31% phosphorus. Breeders on litter floors appear to recycle considerable amounts of phosphorus by coprophagy. Excess phosphorus intake through a combination of dietary and coprophagic sources may reduce shell quality and, indirectly, decrease hatchability.

Magnesium

A severe decline in hatchability has been reported when hens were fed diets deficient in magnesium. Embryonic mortality occurred late (Days 19 and 20) and many of the hatched chicks were morbid and suffered convulsions, coma, and death by 2-day post-hatch.

Zinc

Low levels of zinc are necessary in the breeder's diet to obtain normal hatchability. A zinc deficiency in the breeder diet results in decreased hatchability, increased embryonic mortality, and impaired development of the skeleton and feathers. High dietary calcium levels aggravate a zinc deficiency. 

Boron -Feeding high levels of boron in the form of boric acid or borax to broiler breeder hens decreased hatchability but did not affect egg production. 

Chloride - Inadequate dietary chloride intake resulted in decreased hatchability in broiler breeders. 

Potassium - Hens producing eggs with low levels of potassium in the albumen or high levels of iron in the yolk also had lower hatchability.

Protein and Energy - Breeders fed a low energy-high protein diet tend to produce eggs with lower hatchability. This decrease appeared to result from increased embryonic mortality in mid-incubation and unhatched pips. It has also been shown that a high protein intake increases the requirements for vitamin B₁₂ and pyridoxine. Reducing the energy intake of broiler breeders by 12% did not affect the hatchability of fertile eggs.  A 15% dilution of a standard broiler breeder diet caused no significant effect on hatchability but did significantly increase the chicks produced per hen. Relatively severe reductions in protein and energy intake during the growing period of broiler breeders did not affect subsequent fertility or hatchability. 

Fat and Fatty Acids

The fatty acid composition of the diet has been shown to affect the fatty acid composition of the yolk, which in turn can affect embryonic development and hatchability. Adding corn oil, palmitic acid, oleic acid, or linoleic acid to a basal diet increased hatchability and decreased late embryonic mortality. 

Miscellaneous Ingredients

Feed additives, such as drugs, may affect hatchability. For example, dibutyltin dilaurate and a level of 0.4% acetylsalicylic acid have been reported to have a detrimental effect on hatchability.