Final answer:
Mother cows need a break between nursing and breeding to allow for recovery. This rest period is crucial to replenish nutrients and energy spent during lactation and prepare for another healthy pregnancy.
Step-by-step explanation:
The question asks why mother cows need a break between nursing and breeding. The correct answer is a. To allow for recovery. After a cow gives birth and during the nursing period, the cow's body undergoes intense physiological changes to provide milk for the calf. Lactation is a demanding process that requires significant energy expenditure and can deplete the mother's body of vital nutrients. Thus, a rest period between weaning the calf and becoming pregnant again gives the mother time to recover and replenish her reserves, ensuring she is healthy enough to support another pregnancy and nursing period. Moreover, during the nursing period, suckling by the calf triggers the release of oxytocin, which in turn stimulates milk release. This mechanism ensures that milk production is adjusted to meet the demand of the nursing calf, which is an example of a positive feedback loop. Lastly, it is beneficial for the cow's overall health and future reproductive capability to have this recovery time, made possible by a temporary cessation of breeding activities.