Author(s): Clapp JB, Edward S, Dunn M, Knight M
Abstract: The quality of housing, can impact the welfare and productivity of beef units. This study of 92 Holstein bulls, in 3 age-matched groups per building, compared a conventional barn fattening house with a new design called the Roundhouse. The Roundhouse® (http://www.roundhouseltd.co.uk/) is a new design of farm animal housing, comprising an open sided circular structure with a central handling facility. The original design concept, in addition to reducing operational and building costs, was to mimic the herd environment by allowing a large number of cattle to be in visual contact without being confined in one pen that would increase agonistic behaviour. Additionally, the 3600 field of view from the Roundhouse is argued to reduce perceived risk of predation. Furthermore, the integral handling facility, in full view of conspecifics, reduces separation stress in the cattle. Anecdotal evidence suggests that in the Roundhouse animals are calmer and more easily handled than in conventional housing. Each month while individual bulls were restrained in a crush for weighing, saliva was collected for hormone analysis and their initial heart rate (HRi) was recorded as a measure of stress reactivity. Saliva samples were analysed by LC-MS/MS for cortisol (C), testosterone (T) and progesterone (P). Although there was no effect of housing type on C concentrations, one group had significantly (p=0.020 and p=0.010 respectively) higher T and P concentrations in Roundhouse bulls, suggesting lower chronic stress levels. T and P were highly correlated (r2= 24.7%, p=0.017) in all samples, reflecting the precursor role of P in T synthesis. In time series studies of two crush held bulls, saliva C and T concentrations peaked at 15 minutes, while P remained relatively stable, however dehorning caused all three hormones to be significantly elevated. The expected significant (p<0.05) negative correlation between age and HRi was shown in all bulls. Roundhouse bulls had significantly lower HRi than conventional housed bulls (p<0.001), suggesting the combination of housing and handling facilities was less stressful. Daily weight gain (DWG) from 5 consecutive monthly measurements, showed no significant difference between housing types. For all bulls tested, HRi had a significant negative relationship to DWG (r2=13.1%, p<0.001), importantly linking a higher stress reactivity (HRi) to reduced bull growth rate. Using age-matched groups of bulls to compare housing was problematic because of the wide biological variation between bulls, making a cross over study more appropriate in future. Furthermore because stress responsiveness (HRi) could not separate effects from housing and handling facilities, further studies will use remote heart monitoring of the bulls.