It’s likely more research has been done on the period just prior to and after calving than any other part of lactation. This research has led us to a much clearer understanding of the biology of the cow and growing fetus.
We know that when the fetus hits about 190 days inside the cow, it starts needing more energy, which can only be supplied through glucose and amino acids. We know the udder starts to develop around 260 days in pregnancy, which requires a significant amount of protein. And eventually milk production will increase, which triggers calcium mobilization.
We’ve tailored nutrition programs to adjust to these changes. Our rations ensure her needs for amino acids – conveyed through metabolizable protein (MP) – are met, that she has moderate energy and that DCAD levels are negative enough to help with calcium mobilization.
More to learn
We know a lot about the transition period. But we don’t know everything.
If we knew everything that goes on during transition and managed it accordingly, the incidence of metabolic disorders, both clinical and subclinical, would be a thing of the past. But we know that’s not the case. So what are we missing?
All cows have some level of metabolic disorders when they calve. Most of them can handle minor subclinical hypocalcemia or ketosis without incident. In fact, these may be biologically necessary. But what about those that can’t handle it? Or what about the cow that turns up in mid-lactation with what is thought to be milk fever? What causes certain cows to crash?
What we’re likely missing is the impact of inflammation on the cow. To understand this phenomenon, we need to take a systems approach to managing cows from dry-off through early lactation.
Overactive immune system
In general, inflammation is caused by an overly robust immune system, which is triggered when the cow is under any kind of stress. That could include a challenge by a pathogen that enters through the gut, udder or reproductive tract, something weather-related (more likely heat than cold), mycotoxins in the feed, etc. Certainly, calving is stressful enough to cause inflammation.
But remember that cows are creatures of habit. They like space to lie down, clean air to breathe, a readily available feed and water supply, milking at regular intervals, a quiet environment. Anything to disrupt this idyllic setting causes stress on the cow which, if severe enough, leads to inflammation.
We don’t often recognize inflammation when it occurs because there aren’t any real clinical signs – because the cow has a great poker face. All indicators point to the cow feeling fine, until she’s not and she crashes. During this period, the inflammation process consumes a large amount of energy, as well as other nutrients, at a time when the calf is demanding more and more. And protein demands increase as the udder is rejuvenated. What we are realizing is: The inflammatory responses cows go through during the dry and transition period are likely significant reasons for fresh cow problems.
Perhaps there are two metabolic incidents occurring simultaneously. One could be brought on by a subpar nutritional program. The other could be brought on by any number of stressors. Maybe the cow didn’t eat enough to make the diet work properly – or she was heat stressed, or overcrowded, or had limited access to the bunk, all of which led to a leaky gut incident. Or maybe pathogens entered through the mammary gland as her teat ends started to dilate.
The point is: The cow is hit with all kinds of challenges in her environment which she handles without incident, because that’s what cows do. In the process, inflammation grows, energy demand increases, and the balance inside the cow tips toward a clinical metabolic disorder.
Limit stress and variation
If we don’t eliminate the variation caused by improper management, our management system will fail because we’re creating inflammatory responses that we don’t recognize as a significant detriment to the cow. A solution could be as simple as listening to the cows and keeping them as comfortable as possible.
We see the results of a focus on cow comfort when dairies go through renovations. Often, old facilities were built with labor efficiency in mind. It’s not uncommon for cows to flourish in new systems that center on cow comfort. Somatic cell counts (SCC) drop and production goes up because the systems are fit to the cow, not the other way around. We often hear the owners say, “Once the cows got out of that old, run-down facility and into the new barn, they really liked it.” Now we’re beginning to understand why.
Those facilities that center on cow comfort keep cows cool with fans and misters when it’s hot. They balance rations to maintain body condition and deliver a well-balanced ration at the same time every day, so the bunk is never completely empty. There is always fresh and abundant water available. Rations are kept consistent to prevent sorting of high-fiber forage rations and include refined functional carbohydrates (RFCs) to improve gut health. Cows have plenty of space to lie down and ruminate or stand at the bunk without getting pushed around. When handled, cows are handled calmly and quietly. They calve in a clean, well-bedded pen under a watchful eye that assists only when needed.
Proper ration management and better cow comfort lead to less stress, which means less incidents of leaky gut and fewer immune system triggers. That leads to lower inflammation, which means energy can be used to support the growing fetus and the changes that are going on inside the cow. So when she’s ready to calve she is set up to drop the placenta, lick her calf and withstand the subclinical hypocalcemia and ketosis along with the negative energy balance on her way to a healthy, productive lactation.
