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Stages of Lactation

We feed lactating cows and dry cows in certain phases, we call this phase-feeding. We can divide these into six phases. The first is, is the first 35 days of the dry period and we call this the far-off dry period. The second is about the last three weeks before parturition, this will be the close-up period. Fresh cows, the first two weeks in milk. Cows at peak milk yield, so 14 to 80 days in milk. Then, we look at peak intake which occurs somewhere between 80 and 200 days in milk. And then we have tail end cows in the last third of lactation.

Here are some nutrient densities for far-off and close-up cows.

We can essentially meet the requirement for far-off dry cows almost through forage alone. Energy concentrations are relatively low compared to other stages of lactation. Crude protein is the lowest that you will see in any dairy cow diet. And we have relatively high levels of ADF and NDF. As cows get closer to calving, we want to increase nutrient density of their diet to get them prepared for the lactation diet. You can see in the close-up diet, we have increased energy density, protein, and because energy density increased that means ADF and NDF must decrease.

If we look at the different phases of lactation, graphically, we would start at phase three, which is the first two weeks of milk, that is the fresh cows. Then, we will move onto phase four which is peak milk. Phase five, which is peak dry matter intake. The tail end of lactation. And then we will move into the dry period phases one and two.

The solid white line is milk production. Milk production peaks at somewhere around two to three months in milk. We talked about the suppression in dry matter intake in early lactation and this is the dotted yellow line. We can see that dry matter intake lags behind milk yield and actually peaks about one to two months after milk yield peaks. How do cows meet this tremendous nutrient demand in early lactation when milk yield exceeds what the cow is consuming in energy content? A cow mobilizes body weight, which is shown by the dotted red line. Body weight will decrease up until about the point when we get peak dry matter intake and then the cow will regain that lost weight through the remainder of the lactation. So the goal for fresh cows, if they have not been transitioned with the close-up diet, is to stabilize nutrient intake and stabilize the rumen, or step nutrient intake in two or three increments, so that we do not introduce too much grain at once. But, if you have a proper close-up program for your cows, you do not have to worry about stepping nutrient intake in early lactation. Probably the most important thing is to optimize or maximize dry matter intake because it does lag behind milk yield. However, there are certain management factors that we can do. These being healthy cows, palatable rations, cow-friendly facilities that we can optimize intake and prevent this lag in early lactation. Thirdly, observe the cow and observe her often. The majority of the metabolic disorders that cows have occur during the first two weeks of lactation. If we get past the fresh cow in early lactation, or the first hundred days, what we are looking for, or our goals, are a high intake, or high peak intake, a high peak milk yield and healthy cows. We want this high peak intake to occur as soon as possible. Research has shown that for each pound of milk or for each additional pound of milk at peak, this will turn into 250 to 300 additional pounds of milk over the entire lactation. The quicker we can get cows on full feed or maximum intake, the higher their peak milk yield will be and the more milk that they will give over the remainder of lactation. All cows will have some negative nutrient balance during the first 21, 28, 35 days, it is really cow dependant. But they will be mobilizing body weight in early lactation and it is the most difficult time to manage cows. As we move into mid lactation, nutrient requirements decrease because milk production is declining, intake is at the maximum and at this point we can take advantage of lower cost forages, lower costs feeds, take out some grain, add more forages. And also we want to put back on the body weight that was lost during early lactation.

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