Antimicrobials Used for the Therapy of Necrotic Enteritis and Coccidiosis in Broiler Chickens and Turkeys in Canada, Farm Surveillance Results (2013-2017).

Abstract

Since 2013, the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) has collected antimicrobial use (AMU) and antimicrobial resistance data from sentinel broiler chicken flocks (Br, five provinces) and sentinel turkey flocks (Tk, one province 2013-2015, three provinces 2016-2017). The objectives of this paper were to describe various preventive strategies aimed at controlling necrotic enteritis (NE) and coccidiosis in the broiler chicken and turkey flocks participating in CIPARS and FoodNet Canada Farm Surveillance Program between 2013 and 2017, to quantify and identify trends in antimicrobials used in feed, and to describe temporal changes in the diagnoses of bacterial and protozoal diseases in relation to antimicrobial use in feed. Comprehensive data were collected (by questionnaire) enabling AMU assessment by various count-based metrics (i.e., frequency and number of medicated rations), weight-based metrics (i.e., inclusion rate in feed and kilograms consumed), and technical indicators (i.e., milligrams per population correction unit [mg/PCU]). Qualitative information such as reasons for use and frequency of diagnosed diseases provided context to the trends in AMU. Between 2013 and 2017, 646 broiler flocks (14.9 million kg biomass) and 234 turkey flocks (12.4 million kg biomass) were surveyed. Overall, antimicrobials used for the prevention of Clostridium perfringens infections (NE) contributed to 85% (109/128 mg/PCUBr) and 95% (59/62 mg/PCUTk) of the quantity of antimicrobials administered via feed in broiler chickens and turkeys, respectively. Three NE programs were used: either 1, 2, or ≥3 antimicrobials administered throughout the production cycle. The treatment protocol in which a single antimicrobial was used throughout the cycle was the most frequent NE preventive program for broiler chickens (58%) and turkeys (76%). Bacitracin and virginiamycin were the top two most frequently used antimicrobials in both species for NE. For coccidiosis control, ionophores and chemical coccidiostats contributed to 66% (3091 kg) and 68% (1561 kg) of the total feed antimicrobial exposures in broiler chickens and turkeys, respectively. Documented coccidiosis programs included continuous or straight (1 drug/cycle), shuttle or dual control (≥2 drugs/cycle), and vaccination. Variations in coccidiosis programs between species were noted: broiler chickens frequently used a shuttle or dual-control program (68%), whereas turkey flocks used primarily a continuous or straight program (74%). Flocks raised without antibiotics and organic farms (10.3% of broiler chickens and 9.8% turkey flocks) used vaccines to prevent coccidiosis. A small number of broiler flocks (n = 6) used a combination of a vaccination and a coccidiostat during the cycle. During the surveillance timeframe used for this paper, the total feed AMU decreased over time in broiler chickens from 136 to 120 mg/PCUBr and in turkeys from 85 to 62 mg/ PCUTk, with no remarkable changes in the frequency of flocks diagnosed with bacterial and protozoal diseases. Surveillance findings such as these will be used as valid reference points in light of the upcoming changes in Canadian federal AMU regulations and industry-led initiatives aimed at reducing AMU.