[Truncated abstract] It is well known that cows produce more milk if they are comfortable at milking, because stress from milking may cause them milk ejection problems. Temperament is an intrinsic characteristic of the animals so may affect the level of comfort at milking, and stress from the milking process itself may have a greater impact on animals with nervous temperament than on those of nervous temperament. When the milking becomes a stressor, it may affect secretion of milk ejection hormones that, in turn, may affect milk yield and composition. There is little evidence for how animal temperament affects milk quality in different farm animals. In this thesis, I have examined the effects of temperament on quantity and quality of the milk from Merino ewes and Holstein cows. I also tested whether temperament affected the processing performance (clotting properties) of the milk from Merino ewes. The general hypotheses tested were: 1. Calm ewes would produce more milk of better quality than nervous ewes, and, consequently, the clotting properties would be better in the milk from calm ewes than from nervous ewes. 2. Calm cows would produce more milk of better quality than nervous cows.