The process of dehorning is known to be stressful and painful for cattle (Stafford and Mellor
2005). This study was conducted to compare the welfare outcomes of calves dehorned by scoop
dehorners, dehorning knife or hot-iron cautery.
Forty-four Brahman, tropically adapted composites and Belmont Red/Brahman crossbred calves
(2–6 months old; mean liveweight ± S.D., 135kg ± 25.8) were allocated to 4 treatments: scoop
dehorner (Sc); dehorning knife (K); hot-iron dehorner (HI); and sham-dehorned polled calves (C)
(Animal ethics approval RH255/08). Animals were blocked for liveweight, genotype and flight time
(n=11/treatment). Behaviours during dehorning and on 1, 2, 3, 7, 8, 11 and 14 days post-treatment
were modelled using a Generalised Linear Model. Plasma cortisol concentrations, wound areas and
liveweight changes post-treatment were analysed using general ANOVA.
Age and horn base area had a positive linear relationship (P=0.02). Vocalisations during dehorning
were lower (P<0.05) in the HI group (counts ± s.e.; 4.0 ± 1.2) than Sc (9.8 ± 1.9) and K (10.0 ± 1.9).
Pre-treatment plasma cortisol concentrations (nmol/L ± s.e.) did not differ among treatments (mean
28.3 ± 3.9). At 30 minutes post-treatment, cortisol concentrations of all 3 dehorning treatments
(64.6, 62.0, and 62.2nmol/L for Sc, K and HI, respectively) were greater (P<0.05; s.e. 4.4) than C
(45.7nmol/L) and at 5 hours post-treatment, Sc and K (57.3 and 61.3nmol/L, respectively) were
greater (P<0.05; s.e. 7.7) than C and HI (38.8 and 39.7nmol/L, respectively). Wound size was initially
largest in Sc, was largest for HI at 4 weeks, and did not differ by 8 weeks. More (P=0.04) HI wounds
(82%) had not formed a scab (and were possibly infected) at 4 weeks compared with Sc (30%) and K
(38%). The duration of comfort behaviours (e.g. head shaking, scratching and rubbing) 14 days posttreatment
was significantly (P=0.02) longer in the HI treatment (168 seconds) than in C (29 seconds),
with K (131 seconds) and Sc (65 seconds) intermediate. Liveweights increased for all treatments, and
were similar (P>0.05) at 4, 8 and 12 weeks post-treatment. Horn removal with HI was least effective
with regrowth found in 15 (of 22) horns compared with 4 and 5 for Sc and K groups.
The relationship between age and horn base area indicates calves should be dehorned as soon as
possible. Hot-iron dehorning caused less stress on dehorning day compared with the scoops or knife,
but was largely ineffective, resulting in more animals requiring dehorning again, which is detrimental
to their welfare. HI wounds were slower to heal and were prone to infection after dehorning. It was
concluded that hot-iron dehorning should not be used for dehorning calves in northern Australia.