It’s June going on July, and the southern plains and getting hot! This is the time of year that stresses bison in the south most of all. During times of dealing with heat stress, can come a reduced capacity for resisting herd health antagonists which are ever-present and poised to invade. From the end of June until November, we need to be on our toes and watch for changes in body-scores in our bison. In the south, we have a very explosive end of the cool season forages and minor changes in body scores may be observed as the plentiful spring grasses, forbs and other plants go to seed and make way for the warm season or summer plants. This changes the nutritional regime and may result in ‘window’ realities or minor body score changes between growing seasons and as the heat of summer reduces the protein content of some grass-regimes.  With the explosion of the spring forage during its re-germination cycle, can come excessive amounts of internal parasites.  This is not always true, but can be a factor if you are observing body score changes that concern you.  For that reason I like a feed or water-worming protocol, if needed, at the end of June or sometime in July for the following benefits: 1) If the bison have internal parasites, a worming will put them ‘on the gain’ going in to breeding season thereby catalyzing estrus and resulting in higher calving percentages. 2) A cube worming or water application, will allow me a chance to alternate worming medications which will help prevent resistance in the parasites affecting my herd. 3) I like to reduce the physical stress that my bison are experiencing in the summer, and excessive worm-loads add to physical stress.

One of the ways to determine if internal parasites are a factor in your herd is fecal analysis. Your local vet can perform this service, but there’s a trick to it.  First of all, you want to try and collect feces from the animal or animals in the herd that seemed to have the poorest condition or lowest body score, and are not elderly or sick.  Next you should prepare to transport the feces on ice to prevent the eggs from hatching out. Invert zip-lock baggies, scoop, revert the bag from around your hand, zip and lock. It’s a crappy job but sometimes, someone’s got to do it. .  I also like to split the samples and use two different vets sometimes if I do not have a relationship yet with a particular clinic. Fecal samples can give you a false negative, but never yield a false positive.

In many, not all, regions of the south it is very humid. I have notice that bison in humid heat use shade, whereas in dryer climates they don’t seem to seek it out as much. For this reason, if you are cross fencing and rotating pastures, which is also a very effective way to curb internal parasite loads, I make sure that the pastures with shade are available and rotated to, during the hottest part of the summer. I also like to allow the bison access to wild-water, or natural water sources during this time of year for two reasons: 1) they will use the water to cool themselves and evade flies and 2) The late born calves need to get cool in the first 7 days of life because they are not yet homoeothermic and cannot control their body temperature. I have had multiple cases in which late calves were dying and my recommendation was to open all the gates and let the buffalo find pasture on the ranch they favored. In every case this resulted in reduced mortality, or completely stopping it, because the bison are allowed the performance of natural behaviors to survive.

When things are going wrong in a bison herd, it pays to listen to the buffalo. The big trick is: giving them a way to communicate… with you.

Tim Frasier