Survival of the Face Fly in Feces from Cattle Fed Alfalfa Hay or Grain Diets: Effect of Fermentation and Microbial Changes 1

Abstract

Feces from cattle fed alfalfa hay or grain diets were mixed in various proportions (wet weight) to study their effect on face fly survival. Fecal mixtures containing 10 to 40% grain feces enhanced larval survival and pupal weight. Greatest larval mortality occurred in fecal mixtures containing > 70% grain feces. Fecal pH dropped below 5 within 24 h in the 75, 85 and 100% grain fecal mixtures. Adult eclosion was lower in mixtures with at least 50% grain feces. Fecal moisture content was proportional to the amount of alfalfa hay feces but was not a significant factor in larval survival. Lactic acid concentrations in alfalfa hay feces increased from 17.2 to 31.5 μg/g feces within 24 h whereas grain feces increased from 52.8 to 810.5 μg/g feces. Lactobacilli in alfalfa hay feces decreased from 104 lactobicilli/g to 103/g after 24 h whereas grain feces initially had 107 lactobacilli/g and increased to 108/g after 24 h. Coliform bacteria populations were not affected by as much as 50% grain fecal mixtures but acid produced in the 100 and 75% grain fecal mixtures destroyed coliform bacteria after 24 and 48 h, respectively.