Effects of feedyard manure dust on performance and health of young Spanish goats

摘要

Dust is an environmental stressor and can become extensive in confined animal feeding operations especially during dry environmental conditions. However, there is very little data on the effects of dust stress on animal performance and health. Thisstudy was conducted to determine the effects of simulated feedyard manure dust on the performance and fever status of young Spanish goats with or without Micotil~(R) protection. Thirty six weanling female Spanish goats (average body weight 20 kg) were randomly allotted by initial body weight into groups (replicates) of 3 and placed in pens (n = 12) where feed consumption could be measured. Six pens of goats were randomly assigned to either a control (no dust exposure) or dust exposure. Within each dusttreatment group were nested Micotil~(R) (3 groups) or no Micotil~(R) protection (3 groups). All goats were fed a standard growing diet. Daily feed intake (by pen) was measured and goats weighed individually every 7 d. The dust events were generated by enclosing goats receiving dust exposure in a semi-air-tight canvass tent (183 cm wide X 244 cm long X 213 cm tall) and ground cattle feedyard manure dust was blown inside the tent to create a dust suspension. There were 22 dust events with approximately 7d of rest following 7 consecutive d of dust exposure. Each daily dust event lasted 4 h (0080 to 1200). The control goats were kept in a similar semi-air-tight canvass tent adjacent to the treated groups, except that no dust was blown inside that tent. Oneach day of dust exposure, rectal temperatures were recorded at 4, 8 and 12 h post-dust exposure. Goats protected with antibiotic received intramuscular injection of 10 mg Micotil~(R)/kg of body weight (BW). Rectal temperature (fever response) was measured at 4, 8 and 12 h post-dust exposure on each day of dust exposure. The results indicated that the control goats consumed less (P<0.01) feed but were also less efficient (P<0.05) in feed conversion than the dust exposed group. This response was contrary to our hypothesis. However, goats protected with Micotil~(R) had better (P<0.05) feed to gain ratio than those not protected with antibiotic. Four and 8 h after dust exposure increased (P<0.002) fever more in the dust treated group than the control group increasing their chance of being considered sick. Micotil protection was more effective (P <0.05) only during the first 4 and 8 h after the first single dust exposure. These data suggest the effects of manure dust on the performance of goats require additional investigation. Furthermore, antibiotic protection is effective in alleviating fever during initial dust events but not during chronic events.