Southern Plains Bison: Oct 2015

Conception Rates, Culling Decisions & The #1 Factor


This is the time of year when we all prepare to work our bison and make decisions about our herd based on what they are doing for us, or represent to the sustainability of our economic model. I tend to look at a bison-work, as a survey of facilitation or husbandry that the bison participate in. We collect data such as; body weight, body score, weaning weight [whether we wean or not], yearling weights, conception rate, dentition, and humane handling efficiency. While data-sets and surveys, like many analogous ‘whatever’s’, only work if you use them, it is also true that the analysis is subject to our perception.

As owner-operators we are in charge of having a plan and the answers. The plan should also include the charge of the answers, or results, containing questions and not fearing the ‘why’ of it.  This means: checking attitudes at the door and identifying failures as positives and a chance to improve production, rather than a bad grade.  One such scenario may well be conception rates in the southern plains this year. We’ve had back to back [to back] perfect storms for internal parasite explosions and low nutritional regimes. Too much water – no water – and back to too much water. To example the scenario, we will use a bison work, at the end of October, with a conception rate considered low at below 85%.

Answer: 79% conception rate on October 29th. Question 1] why are they open? Q-2] did my worming program work? Q-3] is my mineral program supportive of their reproductive function – and why? Q-4] Is there a correlation between my opens and their body score? Q-5] are they still breeding?  Q-6] when did my green-feed cycles occur? Q-7] what was my nutritional regime during the breeding season, and how do I know? Q-8] what age are the opens, and how is their dentition [teeth]? Q-9] can I replace her more cost-effectively than keeping her? Q-10] was my bull to cow ratio adequate? These are 10 questions, for one answer, that preclude with the exception of question 8, the cow being the problem.

The southern plains ecology is different than other regions, and many locations within regions can be unique. We have multiple growing seasons, and our timing for the habitats catalyzing estrus may be out of sync with other places where the buffalo roam. Our cool season is our strong-suit, which can result in off-season breeding and calving. Personally; I consider a late-bred, or off-season bred cow – half full, as opposed to half empty.

If you have a conception rate below 90 – 100%, there are many factors that apply and if you are a bison rancher, your criteria for culling is complicated by the fact that you are conserving a species. Culling is a decision that sometimes has to be made, and should be made, for the health of the herd, the operation and the land. Personally; I assume that if I have a cow that is less than 20/ish years old and she misses for me…

I’ve missed something for her… The # 1 Factor…