A cow's puberty is reached around the age of 15 months (the female will be exposed to the bull only when she will have reached 70% of her adult weight). The first calving will take place nine months later (280 days). Left alone, certain extremely precocious females could give birth at the age of 15-16 months. A cow's heat period takes place all year round at regular intervals. The cow in heat will be much more agitated than normal. We may believe she was on a hunt, by trying to get into a neighbouring pasture or starting a head to head combat with another animal.

Puberty of the calf is reached between 9 and 11 months. To detect the critical and determinate period that will allow fertilization, the bull uses the Jacobson's organ, that is specifically used for this function. During summer, you can observe the strange behaviour of the male who activates this olfactory organ by curling up its upper lip. This allows the male to determine from the smell of the cow's urine if the female is in the final stage leading to the oestrus cycle. It is only in the hours preceding this cycle that the cow will allow the bull to climb on her.

Before domestication, the bulls had to establish a hierarchical order determining the mating dominance before and after the period of heat. The age, the weight of the animal, it's conformation and it's personality were leading factors in keeping this order when the oestrus cycle occurred, because the male will follow the ovulating female continually during these 2-3 critical days. To maintain its role with the cow in heat, the male will literally have to drive away all its fellow bulls.

It is very probable that the heat period of the bovine, in that era, took place from the end of summer to the end of fall, a period of the year when the cows had reached a sufficient weight allowing the oestrus cycle to be awakened consistent with the moments of winter paucity and the spring recovery. Considering the incessant male-female activity, added to the dominance contests, the males loose 10-15% of their weight during rutting season. This behaviour may always be present, as long as a cow within the herd is in heat. We may add to these typical behaviours the characteristic bellowing of the bull, a warning signal, during the rut period meaning that it would be better not to approach his territory and that he is the only master of the pasture. To allow all the cows to be sired the ratio should be of 20 to 25 cows per bull.

The gestation period varies from 270 to 290 days. Birthing can take place anywhere from April to July if, in fact, the bulls are removed from their respective herds in late October and reintroduced early in July. Calving takes place without assistance. The new born calves weigh between 22 to 40 kilos (50 to 90 pounds). At birth, the calf is washed from head to foot by a protective and attentive mother. It is in these first few hours that the calf and it's mother will imprint their respective scents and in a lesser extent the sound of their bellows. This imprinting will facilitate mutual recognition of the cow and her calf in the first all important days of survival of the new-born. In the first 24 hours, the maternal milk is comprised of colostrums, a liquid containing all the necessary antibodies for the development of the new-born's immune system. The Scottish people had said that the milk of the Highland was closer to the appearance of butter than of milk. This particularity will allow the new-born calf to increase it's weight considerably on a daily basis.