Lactation Nutrition Cycle Part I
Transcript of Select Sires' Reproductive Moment Program
on DairyLine Radio Which Aired April 27, 2006
With Ray Nebel,
Senior Reproduction and Herd Management Specialist, Select Sires Inc.

Ray, this week we’re talking about nutrition and how it affects reproduction. Let’s talk about the lactation cycle.

Yeah, Bill, normally we think of the cow coming into lactation. And of course the critical period is the dry period 60 days prior to her calving and coming into milk again. And then there’s the transition period until she gets onto full feed and she goes into peak milk. About the time of peak milk production is the time we want to start catching heat and get her bred and get her pregnant for the next cycle. But there’s different nutrition interaction into that reproductive cycle that goes along with that lactation cycle.

Let’s look at this cycle a little closer. What’s the first phase or the beginning of this cycle?

I think most nutritionists and reproductive physiologists or consultants would say the dry period is the time that really sets up the next lactation. In dry cows have a totally different requirement, and the problem that in most places, dry cows are like the stepchild or neglected. We don’t see them everyday; they’re not at the lactating facility anymore, at the milking parlor, so we bring them to a separate group. We move them away from the main facility. They go into different rations. They still have the final stages of the development of that fetus and then getting ready for that next lactation. So very critical is the concentration of minerals that is going to go into setting her up for the next lactation that is going to fall into what happens at calving.

So what is the nutrition advice at calving?

At calving time, what we want to minimize is post-calving disorders. Some of the big ones is ketosis, would be a major killer as far as a cow can go down in ketosis. They go off feed; it takes them longer on going as far as dry matter intake, which slows down the reproductive cycle. Hypoglycemia is where the cows need extra calcium in them so they can have the full calcium for the bone because they can’t have enough intake, uterine infections, metritis: anything that gets a cow down at calving time. A cow is more susceptible at that time and if we don’t have her immunity built up and ready then she’s more susceptible and it will delay the whole cycle.

Let’s talk about that next step, the negative energy balance.

The next big phase in lactation, we’re going to get her up and we’re going to ramp her up to peak milk production. But to do that, her dry matter intake hasn’t kept up with her level of production yet, so she doesn’t eat enough nutrients to balance out the demands for milk production. So 99% of lactating cows will lose body weight. What we want to do is try to minimize that and a way we do it is to try to make as energy-dense a ration as we can to give her in a small package, the nutrients and energy needed to meet those milk requirements that she’s going to be producing. But if we lose too much body condition, what happens again, it delays cyclicity so that cows are later in starting to cycle. When they cycle later, they normally have lower progesterone concentration, so we have lower conception rates, so the whole cycle is delayed. Could be as much as 30 – 60 days because of things that happen after calving.

We will continue next week with Ray Nebel, Select Sires’ Reproductive Solutions specialist.