For many semi-closed flocks, the introduction of rams can bring diseases like ovine brucellosis (OB) a bacterial disease causing inflammation of the epididymis, leaving rams sterile or sub-fertile.
Its may cause reduced lamb marking percentages, an extended lambing period, ill thrift in newborn lambs and culling of rams due to infertility.
Diagnosis is via palpation of testis to feel for swellings or by a blood test or semen examination.
OB spreads ram to ram or via ewes during joining and the only solution is eradication by culling infected rams.
As always, prevention is better than cure.
Your property can become OB-accredited and when purchasing replacement rams, always buy from a OB-accredited flock. Boundary fencing should be secure to prevent straying animals.
For more contact your local vet, Agriculture Victoria Veterinary or Animal Health Officer, or Local Land Services.