We have been taught that you shouldn’t use a word to define itself. However, there are exceptions. Like, referring to an orange as being orange in color. I believe stress is stressful is also acceptable. Put another way, it may go like this “I don’t know what stress is, but I know it when I see it”.
There was a recent technical conference that covered effects of stress on health and production in dairy cows (Discover Conference #35, Itasca, IL). This newsletter pulls some of the highlights from this meeting to illustrate why we are often focused on minimizing stress.
Stress is Normal
For this discussion the focus will be on the animal’s immune system and physiology as it reacts to stress. Under even ideal conditions the animal is going to experience stress. The correct response by the immune system is; rapid reaction, short in duration, and of appropriate magnitude. The opposite reaction may be thought of as; a run-away train, out of control, crash and burn, a disaster.
The process of giving birth is a good example of a normal stress. It is a complex, integrated process involving the immune system to get it started. Yet plenty can go wrong during this normal event. In order for gestation to end, and lactation begin, the cow experiences an inflammatory reaction. This systemic response is an example of an adaptive physiological process required in going from one state (gestation) to another (lactation). During a normal delivery this inflammatory response helps relax the cervix, is involved with uterine contractions, and is important for the release of fetal membranes.
A stressful transition period seems to over-stimulate the inflammatory response causing the train wreck. This is chemical, hormonal, and immunological dysfunction. A successful transition requires the reactions to be just right.
When we think of transition issues, it is usually retained placentas/metritis, ketosis, and/or milk ever. The train wreck is a combination of all 3. In one study, from 2018, cows that had 2 or more incidences of clinical disease around calving peaked 3 weeks later and with 8 lbs less milk than cows that had no clinical disease.
At what “level” do our required management steps become stressful? Are our modern practices stressful? What stress is too much? These questions are not easy to answer. But since most transitions do proceed with minimal negative outcomes we probably have a pretty good handle on minimizing stress around calving. Correct procedures:
- Proper handling, movement. Slow and calm.
- Few moves before calving.
- Assist only when necessary, ie. During an abnormal presentation, or when progression stops.
- Assist to the extent required.
*This list does not replace a proper calving
At the beginning of the year it is a good idea to set goals. For a dairy, this always includes more milk. One area that doesn’t get attention is reduced stress. At two recent appointments we did talk about ideas to minimize stress. One management step that isn’t going away is pen moves.
Dairy A. Two of our consultants were at an appointment discussing diet X pen interactions. Is the right diet being offered to the right pen? In this case, yes it is, but we did uncover some extra pen moves. Since moves are never good1, we discussed options to reduce them. This meant making more high pens. In this case, fewer moves meant a pretty good reduction in labor.
Dairy B. During goal setting last month the manager wanted to focus on operational efficiency. This dairy used pens and moves for management steps, moving animals primarily based on DIM. The cow flow was from fresh pen at 25-28 days to high pen until about 100 DIM. At this time cows were through the initial OVsynch phase. Diet did not change at this time but we were concerned about social changes. Are they major? Probably not. But if you don’t have to move her, why do it? Why penalize her for doing what she is supposed to do? The dairy added 2 high pens so that they remain in this pen until about 180 DIM, or 90 DCC, or until she drops below a certain, as yet undetermined, production amount. The assistant herdsman offered that maybe udder health, SCC, etc will improve without this move at 100 DIM.
Dairy A and B above have just implemented these changes. Two other herds made some changes with pens and moves a few months ago. NOTE – There is never just one change. And it is never appropriate to compare year-over-year performance. But…. One herd gained about 4 pounds of milk (month-over-month). The other is shipping the same amount of milk as they were when using rBST (year-over-year).
Here is a short history lesson2. Dr. Otto Warburg, in the 1920’s, identified that cancer cells and activated immune cells are large glucose consumers. A resting (non-activated) immune cell is about as active as a sloth. Just hanging out, waiting patiently for some stress. The “Warburg Effect” described the rapid upswing in glucose consumption during activation. This means that the immune cells become effective, yet inefficient, users of glucose. Remember, in the case of immune cells, this is normal and required.
There is an important, practical implication to an activated immune system. A properly functioning immune system’s response is rapid, appropriate, and quickly shut down. This normal reaction uses a significant amount of energy. When the immune system is dysfunctional, it is a huge energy hog. During full activation, the immune system can burn close to 5 lbs of glucose in 24 hours. Left uncontrolled, the animal will exhaust the ability to produce glucose. The immune system has 3 potential impacts on the animal.
- The immune system acts quickly, does its job, then shuts down. The amount of energy used is controlled.
- The immune system is over-stimulated. The stress isn’t controlled; glucose is wasted. The glucose could be used to make lactose, which is the biggest driver of milk volume.
- When the ability to make glucose is exhausted, death is common.
I realize this newsletter is a little choppy. But the points do add up to something. The animal’s reaction to stress involves the immune system. Almost everything we do is stressful to the cow. Keeping the stress to a minimum is the goal. Knowing that excess stress causes lots of energy to be used, will keep us focused on the value of minimizing stress.
1Moves are never good. However, they are required. At best, they are neutral to the cow. She would rather be left alone.
2Deep in your memory bank, you may recall something called the Krebs Cycle. The Krebs Cycle explains the production of energy by most living cells. Dr. Warburg mentored Hans Kreb. Perhaps more interesting, is that Warburg was drinking buddy with Albert Einstein.