Lactation education

Key puzzle pieces that impact first lactation milk production

When building a puzzle, many people start with the corners and assemble the frame first. This process is exciting. You start something new and see the scope of the finished product.

However, after building the frame, assembling the middle may seem laborious and monotonous. It’s easy to walk away from the project and forget about it for days, weeks, or even months. When we come back to it, we always have the impression that at least one piece is missing. Even when a puzzle is missing just one piece, it seems incomplete and will never live up to its potential.

Dairy farmers need to be careful that the same thing doesn’t happen to heifers.

Raising heifers can be a lot like building a puzzle. The new life on the farm is exciting and the pre-weaning part of a heifer’s life could easily be considered part of her first lactation milk production. With good reason, producers often pay a lot of attention to the performance of pre-weaned heifers.

Once heifers are weaned and enter the growing phase, they receive much less attention. While it’s true that growing heifers don’t need as much attention, this phase still contains a lot of important parts. Prepubertal growth rate, weight and age at parturition receive little or no attention despite the impacts they are known to have on milk production in first lactation.

Focus on the following key puzzle pieces to ensure that when a heifer enters the milking parlour, she does not miss the last piece.

The pre-weaning room

It’s no surprise that the pre-weaning stage of a heifer’s life has a big impact on first lactation milk production. After all, most producers are aware of Cornell University research showing that for every pound of average daily gain before weaning, heifers produced 850 to 1,113 more pounds of milk during their first lactation. . Similar results were found in studies from Penn State University and the University of Minnesota.

However, having a positive impact on first lactation milk production goes beyond simply feeding more milk to maximize growth rate before weaning. In fact, studies from Penn State University and the University of Minnesota have discussed large amounts of variation in observed responses. They pointed out that although pre-weaning growth rate was an important predictor, a large majority of the milk production response in first lactation could not be explained by pre-weaning growth rate. This means that many factors, in addition to pre-weaning growth rate, affect first lactation milk production.

What better place to start than colostrum? The importance of proper colostrum management is often one of the first topics of conversation between producers, nutritionists and veterinarians. Recent research from Poland has shown that heifers fed high-quality maternal colostrum with initial total serum proteins greater than 6 grams per deciliter produced approximately 3,427 pounds more milk during their first lactation than those whose baseline total serum proteins were lower.

One of the many reasons for this observed response is likely related to improved calf health with increased total serum protein. One would expect healthy calves to produce more milk in their first lactation. Researchers from Penn State University confirmed these expectations. Their research showed that as the number of days a heifer was sick increased, her first lactation milk production decreased. This research also underscores the importance of treating sick animals promptly and appropriately to minimize their sick days.

Starter grain consumption is another factor in this phase of a heifer’s life worth mentioning. While the Cornell University study did not assess the impact of starter intake, the other studies mentioned above did, and they all found it to be positively associated with milk production. of first lactation. A Penn State University study showed that starting intake had the greatest positive effect on first lactation milk production. The other study from Penn State University showed that the predicted milk response more than doubled when the starter intake was included in the model. This demonstrates that first lactation milk production is more strongly impacted when heifers have improved growth from consuming both milk and starter milk, as opposed to improved growth from milk alone.

The pre-pubescent room

The pre-pubertal stage of a heifer’s life is broadly defined as 4 to 10 months of age (or from shortly after weaning through the onset of puberty). Generally, heifers of this age do not require much attention. As such, they often go unnoticed and producers can unknowingly impact first lactation milk production. A meta-analysis conducted by Penn State University found that growing heifers from 1.8 to 2 pounds per day during this period maximized first lactation milk production. This is likely due to the impacts of growth rate on mammary development during this part of a heifer’s life. Growth rate after puberty has not been shown to have a significant impact on milk production. The goal then should be to grow the heifers at the rate necessary to reach the target body weight and age at calving, which brings us to the next step.

The Refreshing Room

The calving stage of a heifer’s life is largely influenced by body weight and age at calving. It has been established for some time that heifers should be 85% mature body weight and 22-24 months old at calving. Most growers are probably aware of these goals and should work towards them, although there have been some recent setbacks.

Recent research indicates that body condition can impact heifer performance in addition to body weight at calving. Research from the University of Florida and Penn State University concluded that heifers should weigh between 73% and 77% of their adult body weight at calving. They came to this conclusion because the heavier heifers in their data set did not last as long in the herd and, therefore, gave up milk for life. The heaviest heifers also suffered the greatest loss of body weight after calving. This may indicate that the reason the heavier heifers did not perform as well is that they were overconditioned. Producers should continue to target 85% mature body weight, while keeping an eye on body condition to deal with milk production and first lactation longevity.

Considerable research continues to show that cooling heifers at 22 to 24 months of age is the economic sweet spot. It becomes costly to leave heifers on forage beyond 24 months. Although the reasons are still unclear, heifers refreshed before 22 months do not produce as well, even when they reach target weight. There just seems to be a physiological limit to how early heifers can be refreshed and still perform at peak levels.

Complete the puzzle

At this point, it should be obvious that there are many pieces of the puzzle in the heifer growth process that impact first lactation milk production. A lot happens in a heifer’s life before she freshens up, and producers can limit their potential if they don’t carefully consider every element of the growth process. A puzzle is not complete until the last piece is in place. Likewise, all the pieces of the heifer growth process must be in place and executed well to optimize first lactation milk production.

Lucas Mitchell

  • Lucas Mitchell

  • Dairy calf and heifer specialist
  • Vita Plus