Updated: Sep 1, 2021
If the cow is exposed to as little stress as possible during the first days after conception, the chances of successful fertilization and implantation of the fertilized ovum into the uterine wall is enhanced.
Pregnancy is divided into three trimesters, each lasting around three months. During the first trimester, the cow is nursing a young calf while the foetus of her next calf is developing. The dam's milk production peaks at the start of the first trimester and gradually declines as the trimester proceeds. Her calf's milk demand remains relatively high, and she must receive more nutrients from her diet in order to replenish her own body reserves. At this stage, the foetus has a low nutritional requirement.
During the second trimester of pregnancy, the cow's calf rapidly develops into a ruminant capable of providing nourishment for its own needs through grazing. Weaning is usually done towards the middle of the second trimester. The foetus is beginning to require more nutrients from the dam, albeit at a low level. The dam can thus replenish her own bodily reserves easily throughout this time if, in the event of seasonal breeding, the timing of the restricted breeding season is correct and pasture management is of good quality. If overgrazing is an issue, or if the veld is approaching the winter dormant period at higher altitudes, actions must be taken to allow the dam to rebuild her body reserves by supplementary feeding. In the event of severe feed shortages, such as during a drought, early weaning of the calf towards the end of the first trimester should be considered to avoid significant body condition loss in the dam.
Since fetal growth is so rapid during the third trimester of pregnancy, there is a strong need for nutrients from the cow. Seasonal breeding reduces the availability of nutrients from natural grazing fields, especially in sourveld areas, when the cow is in the third trimester of pregnancy. Supplemental nutrition is frequently required. Excessive feeding, which results in excessive fat deposition, should be avoided. A period of at least 6 weeks in which the dam does not suckle a calf will allow her udder to rest, allowing involution of the udder tissue to assure a healthy milk supply for the next calf.