Effect of hot-iron branding on the cheek or upper hind limb on cortisol levels, behaviour and production in feedlot calves

Abstract

Hot-iron branding on the upper hind limb in beef feedlot calves is a usual part of the processing procedure at arrival in many feedlots in South Africa. However, cheek branding is becoming more popular in feedlots due to ease of restraint and better visibility of the brand mark. However, the welfare aspects of cheek branding compared to leg branding have not been investigated. By monitoring physiological and behavioural markers this study was conducted to determine potential stress-related differences between feedlot calves which are branded on the leg, those branded on the cheek and control (sham-branded) animals. Thirty weaned crossbred beef calves, recently arrived at a commercial feedlot, were habituated to handling in a crush for seven days and then randomly divided into three groups of ten. Group A was branded on the cheek, Group B on the hind leg and Group C was sham-branded with a room temperature iron. Group C was further divided into two groups (n = 5) that were either sham-branded on the cheek or on the leg. Blood was collected at 0, 30, 60, 90 and 120 minutes after branding for serum cortisol determination with a commercial radioimmunoassay kit. In addition, faeces were collected from all animals on the day after arrival, as well as at day seven, two and one prior to branding, on the day of branding and for seven consecutive days. Faecal glucocorticoid metabolite levels were determined using a group-specific enzyme immunoassay measuring 11,17-dioxoandrostanes (11,17-DOA). Other outcomes monitored included behavioural traits for seven days after branding, individual average daily weight gain (ADG), morbidity and mortality during the feedlot period and histopathological evaluation of the brand mark on the skin after slaughter. Faecal 11,17-DOA concentrations were higher the day after transport than the day after branding (P < 0.001) indicating higher circulating levels of cortisol during transport. Compared to pre-branding levels, serum cortisol was not significantly higher at 30 minutes after branding in all three groups but hormone levels dropped significantly at 60 minutes post-branding. Concentrations at 90 and 120 minutes were not significantly different from pre-branding concentrations in all three groups. The quantifiable rise seen between 60 and 90 minutes post-branding could have been due to the extended time (up to 2.5 hours) spent in the crush. There were no statistically significant differences in blood cortisol or faecal 11,17-DOA between the cheek, leg or sham branded groups at any time. Vocalization occurred more frequently at the time of branding in the cheek branded group than in either the leg branded (P = 0.030) or the control group (P < 0.001). There were also no significant differences in other behavioural indices between the three groups. Faint brand marks could be seen at the time of slaughter (74 days after branding) on five animals from the leg branded group. No cheek brands were visible. No scarring was seen on histopathological examination. No significant differences were seen in the ADG, and there were no morbidities or mortalities. In conclusion, using the methods described, there were no obvious differences in serum cortisol levels, faecal 11,17-DOA levels, behavioural indicators of pain or production outcomes between feedlot calves branded on the cheek, the leg, or sham branded.