POULTRY PUNCH - FEBRUARY 2019

ARTICLE NEWS
Infectious determinants affecting egg
quality and production
1. Introduction
Dr. Atul Kumar1 and Dr. Varun Sankhyan2
1Assistant Professor, Department of Veterinary Public Health & Epidemiology
2Assistant Professor, Department of Animal Genetics and Breeding
Dr. G. C. Negi College of Veterinary and Animal Sciences,
CSK HP Agricultural University, Palampur (H.P.) - 176062
Poultry farming is regarded as a highly profitable livestock venture due to the needed demand for its protein by human
beings. Because of this, there has always been a massive investment in poultry business both for meat and egg production.
Therefore, to meet the demand for eggs by farmers, it is important that farmers meet the optimum nutritional needs of
their layers and maintain a conducive and healthy breeding environment. It is equally important that for farmers to make
profit, their layer chickens consistently lay quality eggs which are sold to the public for consumption. However, for any
animal production or agribusiness like poultry farming, it is quite common to encounter farming cycles where there are
intermittent decreases in egg production and general productivity. Moreover, it is frequently difficult to diagnose the cause
or causes of reduced egg quality and quantity because it isoften a combination of factors that needs to be investigated and
corrected. Management, nutrition and disease alone or in combination are important factors that are responsible for drop in
egg production in a poultry farm. This article will address major diseases and syndromes which have been shown, or are
reported to, have adverse effects on egg production and quality.
2. Infectious determinant
Any disease of poultry can adversely affect egg production and quality either directly, by having effects on the
reproductive system, or indirectly by affecting the health of the bird. Disease micro-organisms that affect poultry include
various organisms of bacterial, viral, fungal, protozoan, and parasitic origin. Generally, any disease that affect laying birds
consequently results to a reduction of egg production in a poultry flock. This is because once a disease affects a bird’s
general well-being, it has a direct outcome on the frequency and quality of egg produced. However, some of the diseases
and syndromes are particularly significant in causing reduction and eventual stoppage in the production of eggs in laying
birds. These include the following;
A. Avian Salmonellosis: It is caused by the bacteria belonging to genus Salmonella (family Enterobacteriaceae)
which consists of more than 2500 serologically distinguishable variants. The serotypes responsible for most of disease in
poultry includes Salmonella enterica serovar Gallinarum (fowl typhoid), Salmonella enterica serovar Pullorum (pullorum
disease), S. enterica serotype Enteriditis and S. enterica serotype Typhimurium. In general, young birds are more susceptible
to Salmonella infections than mature birds. S. Gallinarum and S. Pullorum cause septicaemic disease resulting in decreased
egg production and hatchability, as well as morbidity and mortality (Shiva Prasad, 2000). Experimental infection of birds with
Salmonella Enteritidis increased the incidence of hairline cracks in eggs, leading to an increased risk of contamination.
B. Fowl Pox:This is a viral disease that has a characteristic scab-like lesion on the unfeathered parts of the body.
There is also the wet type (diphtheritic) that affects the mucous membranes of the mouth and the respiratory tract. Fowl pox
causes growth disturbance that will lead to poor feed conversion efficiency and a consequent fall in egg production. Fowl
pox can be transmitted by contact with affected birds or by biting insects.
C. Newcastle disease: This is also a viral disease that has varying levels of virulence and pathogenicity on layer
birds. This variation may lead to a partial to complete drop in egg production or production of thin-shelled eggs. Generally,
Newcastle spreads rapidly and can affect the whole flock with clinical signs that include loss of appetite, coughing, depression,
dropping wings, paralysis, and greenish watery diarrhea. There are no effective treatments for Newcastle but laying birds
could be vaccinated at the appropriate time to prevent against the disease.
D. Avian Influenza: Avian influenza is another viral disease that affects the respiratory, digestive and the nervous
systems of birds. The clinical signs of avian influenza include facial swelling, dehydration, cyanosis, coughing, and
respiratory distress. The severity of the disease results to a decline in the production of eggs. To prevent avian influenza,
70 February, 2019