191 Field validation of mob composite sampling protocol to estimate herd parasitism in cattle

Abstract

Cattle, when initially placed into the feedlot, frequently carry a significant internal parasite load, that if unaddressed, can result in weight loss, poor growth, and increased susceptibility to illness due to immune suppression. To combat these challenges, many feedlot animal health protocols include administering anthelmintic treatments immediately upon feedlot arrival. The detection of parasite loads and potential resistance to anthelmintic drugs typically involves fecal egg count protocols conducted using trained laboratory methods. However, these tests can be costly and may not be consistently used across operations. This study aimed to evaluate the efficacy of existing fecal sampling protocols against a modified mob composite sampling approach, intending to reduce cost and time required for results while encouraging more frequent sampling in commercial settings. A total of 920 fecal samples were collected from cattle (both calf-fed and yearling) in commercial feedlots across the midwestern United States. The cattle, originating from various sources (n=13), were either being sold at a sale barn or transported to feedlots or stocker units for finishing. Samples were collected from fresh fecal pats on the pen floor shortly after the arrival of the animals, with effective communication among feedlot managers and employees being crucial to ensure sampling occurred prior to anthelmintic treatments. Each sampling set corresponded to a pen of cattle (n=46), with pen sizes varying from 64 to 225 head, depending on the specific commercial operation. From each identified fecal pat, approximately 15 ml of material was collected from three different sites. This homogenized mixture of approximately 45 ml constituted one individual sample (IDV). The process was repeated with 20 distinct, fresh fecal pats within each pen, reflecting the industry-standard sampling protocol. The average of the 20 samples provided an eggs per gram (epg) value indicative of the parasite load within that cattle group (range 0 to 444 epg). For mob samples (n=92), 7.5 ml from ten individual samples were combined. Each pen produced two composite (MOB) samples, which were mixed by stirring in a smooth-sided cup using a tongue depressor. The averaged values from these two MOB samples yielded an epg representing the parasite load for that group. To evaluate the effectiveness of the MOB sampling method in producing values comparable to the IDV industry standard, Lin’s concordance correlation coefficient was utilized. The analysis revealed a 91.7% agreement in mean fecal egg counts between the MOB and IDV methods, with a 95% confidence interval ranging from 86.4% to 95.0%. These results suggest that the two-sample mob approach, utilizing a tongue depressor and smooth sided cup for mixing, may provide an acceptable method for assessing parasite loads in commercial feedlot operations, thus enhancing efficiency and cost-effectiveness.