Short communication: Relationship between serum cortisol concentration and defensive behavioral responses of dairy cows exposed to natural infestation by stable fly, Stomoxys calcitrans

Abstract

The aim of this study was conducted to evaluate the effect of natural infestation by Stomoxys calcitrans on the behavioral and adrenocortical responses of dairy cattle. Twenty Holstein cows randomly selected were individually sprayed with insecticide once every 7d, whereas no insecticide was applied to the other 20 animals. The average number of flies per cow was estimated daily, and the frequency of fly-avoidance behaviors was measured daily; plasma cortisol concentration was measured each morning. No flies were ever counted on the treated cows at any time during the experiment, whereas an average of 17.13±1.14 (±standard error) flies/d were recorded on untreated cows. Tail movement was the most frequent behavior displayed, with stamps or kicks showing the highest increment rate (41.2×) when fly population increased from zero to greater than 51 flies/cow. Cortisol concentration increased to a maximum of 56.81±39.53ng/mL with 26 to 30 flies/cow per day. Coefficients of determination between the number of flies, cortisol concentration, tail movements, and stamps or kicks were 0.73, 0.78, and 0.81, respectively. The multiple correlation coefficient was 0.90, with 81% of the variation in cortisol concentration explainable by variation in the number of flies per cow and the frequency of fly-avoidance behaviors. It was concluded that plasma cortisol concentration is linearly related to a combination of the number of flies and the frequency of fly-dislodging behaviors, producing a maximum response before reaching maximum fly loads.

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

“…Stable flies ( Stomoxys calcitrans) are biting flies that feed on blood leading to high stress and elevated cortisol levels which may impact cattle health, productivity and welfare [1]. Previous studies have reported severe reduction in US dairy and beef cattle productivity due to S .…”

“…Cattle might differ in how aggressively they engage in fly-repelling behaviors according to their breed, color, parity, productivity, and the number of stable flies attacking them [9–11]. Fly-repellent behaviors include tail flicking, foot stomping, head tossing, skin twitching, and ear trembling to reduce the fly attack [1, 9, 10, 12]. Additionally, cattle tend to aggregate in a tight group with their heads to the center of the group and their tails to the outside to protect themselves against the stable fly attack displaying a behavior known as bunching [12–15].…”

A Historical Review of Management Options Used against the Stable Fly (Diptera: Muscidae)

“…Cattle often bunch together when attacked by stable flies to avoid being bitten; this often leads to heat stress and reduced feeding [12][13][14]. Serum levels of the stress hormone cortisol increased in dairy cows in response to higher numbers of stable flies on them and their associated fly-dislodging behaviors [15]. Their painful bites can reduce milk production in dairy cows, decrease weight gain in beef cattle and affect feed efficiency [16] with national losses in cattle production for the US alone being over $2 billion [17].…”

HPLC‐QTOF method for quantifying 11‐ketoetiocholanolone, a cortisol metabolite, in ruminants' feces: Optimization and validation

“…The measurement of the concentration in the blood (serum or plasma) of stress hormones has been the method most commonly used to assess the effects of stressors in large free-ranging vertebrates such as ruminants (Keay, Singh, Gaunt, & Kaur, 2006;Sheriff, Dantzer, Delehanty, Palme, & Boonstra, 2011;Vitela-Mendoza, Cruz-Vazquez, Solano-Vergara, & Orihuela-Trujillo, 2016). However, this technique requires capture and handling of animals for sample collection, which can artificially increase biological stress and therefore give biased plasmatic GC concentrations.…”