Animal health matters: When too many cows come up open

Russ Daly Special to the Farm Forum
Farm Forum

The chute was in place and my OB sleeve attached to my left shoulder. The day after Thanksgiving was Don’s traditional date for preg-checking his herd, as he could count on his school-age kids for cow-pushing help. It had been a while since I last caught up with Don and his crew, and the banter and mood was jovial as the first cow moved toward the headgate.

The first cow was cooperative and the answer came quickly. “She’s good!” There’s something about a good result on the first cow of the day that elevates an already good mood; you could see it in the crew’s energy levels. This was going to be a good day.

Cow number two took longer, though. The almost-immediate bounce from a mid-term fetus wasn’t there. Thorough palpation of the uterus revealed no sign of pregnancy. “She’s open,” I called. Don looked puzzled but not dejected. A 100% pregnancy rate would be great, but isn’t realistic. A few open cows are to be expected.

Unfortunately, that open cow wasn’t the only one. Twenty cows in, we’d already found six open. With every “She’s open,” Don’s demeanor soured. As the day went on with a similar percentage of opens, you could almost hear him working through the stages of grief.

Denial: “That cow? She can’t be open, doc. Are you sure?”

Anger: “That #$@% sale barn bull was a dud!”

Bargaining: “If only I would have put out better mineral…”

Depression: “This is terrible. It’s going to break me.”

And finally, acceptance: “OK, doc. This didn’t go so well. What went wrong?”

An obvious question, but not always an easy one to answer. Whether the problem rests with the male or the female side of the equation (or some of both), the list of possibilities is long.

The major challenge in diagnosing the reason for a high rate of open, or non-pregnant, cows is that the recognition of the problem at preg-checking time usually comes long after the causative factors were at play. The current attributes of the herd and its environment are usually quite different now compared to the beginning of the breeding season.

In beginning such an investigation, a calendar and a map might be the most useful tools of all. A full story of the breeding season often gives more clues than anything lingering in the cow or bull. History of bull usage is a good place to start when there’s a high percentage of opens. Were the open cows with just one of the bulls, or were multiple bulls and multiple pastures involved?

What was it about the open cows? Were they older or younger? Maybe in poorer body condition than the pregnant cows? Were they moved or vaccinated at the wrong time? The answers to these questions often provide valuable clues.

That’s not to say that the animals themselves might provide good information. The challenge, however, is that a problem that occurred in July could be healed or resolved by late fall. In bull-bred herds, suspect bulls should be given a thorough once-over, including a breeding soundness examination. Are there injuries (healed or otherwise) in the sheath, limbs or eyes? A poor semen test is telling, but since sperm production problems can be temporary, a satisfactory test at the end of the breeding season doesn’t necessarily reflect what was happening earlier. Trichomoniasis testing should also be part of the exam.

In the cows, infectious diseases such as Bovine Viral Diarrhea Virus or Red Nose are possibilities. Here again, an infection or problem that occurred months ago might be less detectable now. Additionally, most cows have been vaccinated for such diseases, which can confound diagnostic blood tests. Testing open cows and comparing their results with pregnant cows sometimes helps sort that out.

Unfortunately, a lot of times we don’t come up with a clear answer for why our cows didn’t get pregnant. We can, however, come up with a list of possibilities —most of which we can do something about before next breeding season. Your veterinarian is the best person to help sort these interventions out and will help you target the management changes needed to prevent a discouraging preg-check next year.