Alterations in serum calcium and phosphorus levels, organ lesions and their relationships to egg production in point of lay pullets infected with Salmonella Gallinarum.

Salmonella Gallinarum (SG) is a bacterial pathogen associated with serious economic losses to the poultry industry worldwide in the form of decrease in egg production. In this study, the dynamics of serum calcium, phosphorus levels as well as lesions in some body organs, and how they relate to egg production in point of lay pullets (POLPs) infected with SG were investigated. Fifty POLPs (18 weeks old) were randomly assigned to two groups of 25 POLPs per group viz.: Infected POLPs orally inoculated with SG (109 SG colony forming units/mL), and uninfected controls. Biochemical parameters were assayed following standard methods, and relevant tissue sections processed for histopathology. The infected POLPs showed significant (P < 0.01) drop in egg production when compared to the controls. The mean serum calcium level was significantly (P < 0.05) lower, whereas the mean phosphorus level, mean serum malondialdehyde (MDA) level, and catalase (CAT) activity were significantly (P < 0.05) higher in the infected POLPs than the control group. There was a strong positive correlation between serum calcium level and egg production which was highly significant (r = 0.60; P < 0.01). The relationship between serum phosphorus level and egg production was negative and moderate, but highly significant (r = -0.45; P < 0.01). There was extensive pericardial effusion as well as inflammatory, necrotic and degenerative changes in the heart, liver, uterus, ovaries, kidneys, lungs and intestine of the infected POLPs. It was concluded that the drop in egg production associated with SG-infected POLPs had a strong and positive correlation with the decreased serum calcium level.