Risk factors affecting dairy cattle protective grouping behavior, commonly known as bunching, against Stomoxys calcitrans (L.) on California dairies

Abstract

Bunching is the term used to describe the protective aggregating behavior of cattle against the painful bites of stable flies (Stomoxys calcitrans), where cattle gather in a group with their heads to the center of the group and their tails to the outside to reduce stable fly attack. Both sexes of the stable fly feed on blood, and their painful bites negatively impact cattle health, productivity and welfare. A longitudinal study was conducted from April to July 2017 to estimate the stable fly activity on 20 California dairies (average herd size = 2466 ± 1050), to determine stable fly activity that induced bunching, and to evaluate the association between management and environmental factors, and cattle bunching. Stable fly activity was recorded weekly using trap counts and leg counts. Data was analyzed using linear mixed models with odds ratio. Cattle bunching at the dairy level was predicted by mean trap counts of ≥150 flies/trap/week, while bunching at the pen level was predicted by mean leg counts >1 fly/leg/cow or mean trap counts >50 flies/trap/week for traps closest to the pen. Additional risk factors predicting cattle bunching at the dairy level were study week (May/June vs July), presence of crops adjacent to dairy >2 sides, and feeding wet distillers grain. Additional risk factors predicting cattle bunching at the pen level were study week (May/June vs July), ambient temperature ≤30°C, pen design (freestall vs open dry lot or bedded pack), production status (lactating/dry vs close-up), presence of crops surrounding cattle pens, feeding rations containing molasses. Cattle bunching was reduced at the pen level by relative humidity >50%, and when the cattle pen was surrounded by other cattle pens or was bordered by a main road. At the dairy level, removal of manure along fence lines of cattle pens was protective against cattle bunching.

Virtual Fence Responses Are Socially Facilitated in Beef Cattle

“…Group-level responses in a potentially threatening situation are one of the benefits of group-living (43). Other research has shown cattle will act as a coordinated group in their patterns of avoiding biting pests (44,45). In the case of the VF, the stimuli are initially highly unexpected with no visual cues and a benign audio tone as a warning for the electrical pulse.…”

Possible causes of aberrations in adverse grouping behavior of dairy cows: A field study

“…Additionally, fans can produce noise that may annoy the cows or may be installed to repel biting insects. Grouping behavior of cows as a result of biting stable flies has been observed in California and described by El Ashmawy et al (2019). Interestingly, relative to control farms, the case farms more often mentioned a high burden of flies but less often applied insecticides or applied only nonchemical insecticides (Table 3; P ≤ 0.10), but these factors were not retained in the final multivariable model.…”

“…They hypothesized that avoiding heat as well as stinging insects might be the cause of this behavior. Stinging insects are known to cause grouping behavior of cattle, known as bunching (El Ashmawy et al, 2019).…”

Stable fly activity is associated with dairy management practices and seasonal weather conditions

“…Data for this research was part of a larger study that investigated the epidemiology of cattle bunching [16]. Briefly, the current study data were collected from 20 dairies in Tulare and Kings Counties between April 26 th , 2017 and July 31 st , 2017.…”

“…Bunching can contribute to reduced feed intake, weight gain, and milk production by individual cattle [15]. Cattle bunching is positively associated with the number of stable flies biting cattle on the front legs [16]. The estimated average loss to U.S. cattle industries induced by Stomoxys calcitrans was $2.2 billion per year in 2009, with $360 million lost from the dairy industry alone [4].…”