Western
Meeting of Poultry
Clinicians and Pathologists
|
Clinicians and Pathologists
|
Coccidiosis in Saskatchewan Broiler Chickens
Poultry Extension University of Saskatchewan
In 1998, it was noted that three separate farms in the province were experiencing repeat problems with necrotic enteritis (NE) in 24-28 day old broilers. Post mortem findings indicated that coccidiosis was associated with wheat and barley based diets and not coccidiosis. Outbreaks of cecal coccidiosis do not occur sporadically. Surveys of 21 to 35 day old birds conducted in 1993 and in 1996, that included an evaluation of the gut for coccidial lesions, found no gross lesions associated with coccidial infection. Litter in Saskatchewan broiler barns is typically very dray at 28 days post placement (<24% summer); it is speculated that the low moisture content of the litter prevents oocyst sporulation, resulting in a low coccidial challenge. Because of the low incidence of coccidial disease, rotation of coccidiostats and/or use of shuttle programs was seldom done. In some cases producers have used the same coccidiostat for 5 or 6 years. From May 1999 to August 1999 a survey of eleven broiler flocks was conducted to determine if the incidence of coccidial lesions was increasing in all Saskatchewan flocks or just on specific farms. Two of the three problem flocks were included in the survey. The remaining flocks were selected at random. (One half of these flocks will be monitored in the fall, winter and spring). Eight (8) flocks were visited at 21 and 28 days. Three (3) flocks were visited at 25 days only. All flocks were checked at slaughter. Data Collected: Coccidiostat and Growth promotant Barn Temperature, Humidity and Litter moisture Gross lesion score Fecal Oocyst counts Gut scraping oocyst count Feed conversion and average daily gain Results: It was found that two different coccidiostats (ionophores) and two different growth promotants used by all the feed mills involved. Temperatures ranged from 74oF to 85oF, relative humidity ranged from 55% to 83% (Avg 66.9%), litter moisture ranged from 25% to 38% (Avg 30%). It should be noted that the summer of 1999 had significantly higher precipitation that usual for Saskatchewan, which may account for the higher humidity and perhaps higher litter moisture. Gross lesions were found in all but one flock. The lesions were seen in the duodenum and proximal jejunum and were consistent with those attributed to E. acervulina. Gross lesion scores of +1 was the most frequently observed, no lesions scores greater than +2 were noted. In the flock with no gross lesions no oocycts were seen in the gut scrapings. High litter moisture content did not consistently correspond with increased lesion scores. For each feedmill the poorest feed conversion did correspond with the farm that had the highest gross lesion scores. The findings from this survey indicate that the incidence of coccidial lesions was higher than had previously been found in Saskatchewan broiler flocks. It could not be determined if the climatic conditions played a role in the observed increase. Nor could it be determined if the prolonged use of the same anti-coccidials has resulted in resistance in the coccidia population. The implementation of Rotation and or Shuttle programs has been suggested to producers. |
|
To send us your comments or questions regarding this web site, click here. |