Screening of depigmenting compounds for the development of an alternate method of branding beef cattle.

The impetus to find alternative methods to stressful routine management procedures has increased in recent years in the hope of improving animal welfare. The potential of using depigmenting compounds to create a permanent visible mark was evaluated in two beef heifers. Eight compounds (hydroquinone [H], 4-ethoxyphenol [4-EP], 4-methylcatechol [4-MC], 4-tert-butylcatechol [4-t-BC], 4-methoxyphenol [4-MP], monobenzone [M], hydroquinone bis (2-hydroxyethyl) ether (HHEE), and catechol [C]) were injected intradermally at concentrations of 10 and 20%. These compounds were screened in four different carriers (ethanol, glycerol, propylene glycol, and liposome cream) to test their effectiveness in producing depigmented hair. Transdermal patches containing 5, 7, and 10% liposome preparations of 4-MC and 4-MP produced depigmentation, but this depigmentation was not as visible as when the same preparations were injected. Histological examination of biopsies and observations of the injected sites were compared to sites that were only injected with the carrier solution. Compounds H, 4-EP, 4-MC, 4-t-BC, 4-MP, and M produced visible depigmentation lasting up to 3 mo. The duration of the effect seemed dependent on the hair cycle length and stage of cycle at time of application. None of the depigmenting compounds tested produced a permanent depigmenting effect.