All animal procedures were conducted at the University of Glasgow Cochno Farm and Research Centre (55° 55′N) under Home Office Regulations (Project License: 60/4422). The experimental animals used in this study were Scottish Mule, Texel cross males, born from same sex litters between 23 March and 12 April 2013. At birth, lambs were assigned to one of the treatment groups described below. Lambs from twin and triplet pregnancies were allocated to different groups, so that only 1 sibling was represented in each treatment group. Puberty was delayed in the GnRHa-Recovery (GnRHa-Rec, n = 25) lambs by subcutaneous implantation of the GnRHa, goserelin acetate (Zoladex 3.6 mg, kindly donated by Astra Zeneca, Macclesfield, UK), every four weeks from 8 to 44 weeks of age (average age of pubertal onset in male sheep is 10 weeks of age (Wood and Foster, 1998) and are expected to be sexually competent within the first year of life). Control (n = 30) and GnRHa-Rec rams were grazed on pasture, except during behavioral trials, when they were housed indoors with ad libitum access to hay or silage, with supplements as deemed necessary by standard management practices. All animals were euthanized at the end of the study period, when they were approximately 2 years of age.