Link May Exist Between Disposition And Reproduction

By: Ryan Sterry

Experience tells most producers that high strung, poorly tempered stock, sometimes do not perform as well as herd mates with a more moderate disposition.  Science has backed this up in the feedlot with studies showing steers with calmer dispositions outgaining steers with the most excitable temperaments.  Links are also being made by research between disposition and health, including response to vaccination.  Most of all, stock with a bad temperament pose a greater risk to you being injuring during handling.

Determining if a link exits between reproductive performance and disposition has been difficult to prove.  Anecdotally, producers and A.I. technicians have noted that cows with bad temperaments are less likely to conceive to A.I.  However, putting hard numbers to this has proven difficult.

In an experiment at Oregon State University by Reinaldo Cooke, crossbred heifers were divided into two groups.  After weaning one group was trained for handling by being brought up from pasture to a pen three times a week, for four weeks, so that they’d become acclimated to people and going through a working chute.  The other group was not handled during this time and was left on pasture.  Both groups were tested for the hormone Cortisol. 

This hormone is associated with stress and is part of the “fight or flight” response in animals.  When Cortisol levels are elevated, it is an indicator of stress.  Some research indicates elevated cortisol levels impair the naturally occurring reproductive hormones LH and FSH, and could help explain why stressed or poorly tempered animals may have poorer fertility.

Since these were young heifers not ready to breed yet, you might be asking what could possibly be proven by this experiment.  The results of this study found two important differences in the trained group that could impact reproduction down the road.  First, the group that was handled had lower Cortisol levels at the end of the four week training period than the non-trained group. 

Secondly, the trained group reached puberty at a faster rate than the non-trained heifers, with nearly a 20% difference in the number of heifers cycling five, six, and seven months after the project began.  Having these heifers start cycling sooner can greatly improve reproduction by allowing heifers to be bred sooner and calve early in the calving season.  These heifers will ultimately have more time to recover before breeding again as first calf heifers, and have a greater opportunity to maintain an early caving interval throughout their lives.

A similar study was done at the University of Florida by Cooke, this time with mature cows.  One group had the same worker walk the pen twice a week offering the cows a small treat (range cubes), while the control group was left alone on pasture.  In this case, the group that was worked with showed no difference in Cortisol levels or pregnancy rate at the end of the breeding season.  However, when disposition score was looked at alone regardless of treatment, cows with the most agitated and aggressive scores had lower pregnancy rates at the end of the 90 day breeding season.

Putting a temperament score to your own stock is rather easy.  Use a scale of 1 to 5, with one being calm, and five being very excited and / or aggressive towards people.  This scoring scale can be used while animals are in the chute and when they are in the pen.  A chute exit speed score and also be assigned as animals leave the chute, with one being the slowest and five the fastest.  These three scores can be averaged to give an overall score to each animal.

While a definitive link between disposition and reproduction has not been made yet, research is starting to show tendencies that one may exist.  A key point of this early research is temperament and fertility is not just a concern for A.I. breeding.  Studies using natural service bulls have shown the same tendency for poorly tempered cows to have poorer fertility.   Bottom line, there are already many good reasons to cull cattle with bad temperaments, to consider disposition as part of your breeding criteria, and train your stock to be handled.  If you don’t already do so, improving reproduction is one more reason to reconsider adding these management practices to your herd.

Source:uwex.edu