As the breeding season approaches, University of Arizona extension specialists offer several suggestions on monitoring your herd for potential breeding problems.

* No heat Leading up to the breeding season, watch your cows for signs of estrous activity. Typically, about 5 percent of the herd will be in heat on any given day. If your observations suggest a lower-than-expected percentage of cows coming into heat, consider having your veterinarian examine a sample of cows to determine whether they are cycling normally. For cows that are not cycling normally, rectal palpations can determine causes such as uterine problems or pregnancy. In the absence of obvious physical problems, environmental or nutritional factors are likely causes for interruptions of normal cycling.

* Weak or silent heat Some cows, especially older cows or first-calf heifers, can have difficulty reestablishing their estrous cycles 30 to 60 days postpartum. Marginal copper deficiency is a possible cause of weak heat. If a high percentage of cows show a reduction in heat activity, have some checked for serum copper levels. Short-term removal of calves is another possible method for improving heat activity in a herd showing weak or absent heats.

* Persistent heat Occasionally cows will remain in heat or return to heat every few days. A likely cause is a cystic ovary, in which the egg is not released normally. Palpation can confirm this condition, and cows with cystic ovaries should be treated to induce ovulation.