A note on the effect of controlling stable flies (Stomoxys calcitrans) in the resting activity and pen distribution of dairy cows.

This study investigated the effect of controlling stable flies (Stomoxys calcitrans) on the number of dairy cows lying down and their pen distribution. The study randomly assigned 80 Holstein cows to 1 of 2 groups. The treated group (T) included cows individually sprayed with insecticide when found with an average of 10 stable flies per cow; in the control group (C), cows received no application of insecticide. The pen had 4 equal-size areas: (a) feeding, (b) drinking and sunny, (c) covered, and (d) manure. The study recorded the number of cows lying and the area of the pen where the nonhuman animal was located. The study found no difference (p > .05) between the proportion of T and C cows lying. However, cows preferred to lie down in pen area 3 when fewer than 10 stable flies per cow were found. Area 4 was the most avoided section of the pen, except when a high incidence of flies was present. The study concluded that high populations of S. calcitrans (> 10 flies per cow) did not affect the number of dairy cows lying down. However, it modified site preferences for lying.