By Kelli Jones etal
Hen diuresis (excessive urination) syndrome has emerged over the past five years as a significant cause of mortality in the US broiler breeder industry. The condition affects hens in production and is characterized by transient muscle weakness in the vent region, transient diuresis (most commonly occurring in the early to mid-morning), and often urate deposits on the skin below the vent. Affected hens are often seen straining to lay an egg, which suggests uterine contraction, is also inhibited.
Related hen mortality, often reaching one percent or more per week, is believed to be primarily the result of male aggression, which causes trauma of the vent region. When male aggression is not present, mortality is generally lower (~0.5 percent a week) and is the result of E. coli peritonitis infections. The exact association between the cause of mortality and this syndrome is unknown, but may be the consequence of transient partial to full oviduct prolapse. Up to this point, cases have been generally sporadic, although in at least three instances the problem has been widespread within individual complexes. Evidence of the condition at low levels has been identified in many flocks with normal mortality.
Based on work done prior to this study, evidence suggests that the underlying problem is metabolic and related to egg production. This problem is difficult to study because of the difficulty of collecting urine in birds, since birds evacuate feces and urine together from the cloaca. In order to study this syndrome, a reliable method to collect urine from chickens is needed. The
ultimate goal of this pilot study was to determine if surgical colostomy of hens would provide a means for collecting urine for analysis.
In this study, colostomy was successfully performed. The colon was surgically separated from the urinary tract and attached to a new surgical opening in the abdominal wall of the birds. Over the course of several days, we collected urine samples from clinically "unaffected" and "affected" birds, which had undergone the colostomy surgery. Analysis of the samples gave an indication of how long after colostomy urine is affected.
Based on normalization of urine sodium levels, colostomy surgery appeared to affect urine content for around 32 hours after the surgery. Based on this finding, sample analysis began at this time point. Two urine values were statistically different between "affected" and "unaffected" groups. "Affected" birds had higher sodium and lower potassium urine values compared to "unaffected" birds. In addition, as was expected, urine output was higher in the "affected" group. Our findings support our hypothesis that this syndrome has a metabolic basis.
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