Effects of bill-trimming Muscovy ducks on behavior, body weight gain, and bill morphopathology

In commercial production facilities, ducks are often bill-trimmed to prevent feather pecking and cannibalism. Beak-trimming of chickens and turkeys has been criticized because of its potential to cause acute and chronic pain, but little is known about the effects of bill-trimming on the welfare of ducks. We conducted a study to determine the effects of a commercial bill-trimming method, cutting without cautery, on the behavior and bill morphopathology of ducks. Muscovy ducks were housed in six pens each containing 16 ducks (eight males and eight females). Three pens of ducks were trimmed (TRIM) using scissors at 20 days post-hatch, while ducks in the remaining three pens were sham-trimmed (NOTRIM). The average length removed from the upper bill was 0.51 cm, or 21.1% of the bill length from nares to tip. The behavior of all ducks was recorded during the first week post-trim using scan sampling. In addition, two ducks/sex/pen were randomly selected as focal birds, and observed using 15-min focal samples during the morning (0900-1100) and afternoon (1200-1500) for 7 weeks post-trim. Ducks were weighed weekly. Behavioral and body weight data were analyzed using the General Linear Model. At 12 weeks of age, the male focal ducks were killed and their bills were then collected and subjected to gross and morphopathological analysis. In the days immediately post-trim, TRIM ducks spent significantly less (p < 0.0001) time engaging in bill-related behaviors (preening, feeding, drinking, exploratory pecking) and more time resting than NOTRIM. These differences disappeared by 1 week post-trim. At 1 week post-trim the TRIM ducks weighed less (p = 0.0064) than NOTRIM, but there was no treatment difference in weights by 2 weeks post-trim. By 6 weeks post-trim the upper bill of TRIM was only 11.9% shorter than the lower bill. There was evidence of feather pecking in the TRIM pens, but feather pecking and skin damage were more extensive in the NOTRIM pens. The TRIM bill stumps were covered with epithelium, lacked blood vessels and showed evidence of scarring, but there were no neuromas. These results are consistent with this bill-trimming method causing acute, but not chronic, pain in Muscovy ducks. (c) 2006 Elsevier B.V. All rights reserved.