The Resurgence of Milk Recording in Spring-Calving Herds
Thirty years ago, milk recording was often abandoned by spring-calving herds as a way to cut costs and streamline operations. At the time, breeding replacements focused on the most fertile cows at the front of the calving block, aiming for a 12-week calving spread. However, as these herds maintained their compact calving patterns over time, there has been a noticeable shift in approach.
Today, many spring-calving herds are reintroducing milk recording, with estimates suggesting that between 50% and 75% of the herds Piers Badnell, a farm consultant from LIC, works with have resumed the practice. This change is driven by several factors, including the requirements of milk buyers who now demand tests for Johne's disease control and cell count data for the selective use of antibiotics during drying off.
Another contributing factor is the availability of more flexible services tailored to grazing systems. These services make it easier for farmers to integrate milk recording into their existing practices without disrupting their operations. Additionally, milk recording has evolved beyond just monitoring milk quality; it has become a valuable source of data that helps identify the best-performing animals for breeding the next generation of heifers.
Grass-Based Systems and Productivity
In grass-based systems, productivity plays a crucial role because the amount of grass that can be grown determines stocking rates and herd size. If land area is the limiting factor, it becomes essential to select the most productive and efficient cows for breeding. This is because buying in large amounts of feed is not economically viable.
Piers explains that efficiency is measured in kilograms of milk solids (MS) relative to a cow’s mature weight. This metric is calculated individually for each cow and reflects how effectively a cow converts feed into milk production. The most efficient cows achieve a 1:1 ratio of MS production to mature cow bodyweight.
For example, a cow that produces 313kg of MS and calves on the first day of the calving block may have excellent fertility but might not be the most efficient in terms of body size. Milk records can highlight this discrepancy, showing that even a seemingly uniform herd can have significant variation in body depth and frame strength.
Case Study: The Importance of Understanding Variability
One case study involved a farm where the average mature liveweight of the herd was 543kg, but the range extended from 417kg to 736kg. This wide variation underscores the importance of not relying solely on averages, as they can mask significant differences among individual animals.
The Role of Sexed Semen in Breeding Strategies
As with any biological trait—such as height, weight, or yield—milk production results typically form a bell-shaped curve, indicating a natural range of values within a herd. Over time, through selective breeding, it is possible to shift this curve to the right by eliminating less productive animals.
Sexed semen is playing a key role in this process. By using dairy sexed semen, farmers can focus on breeding the most efficient cows in the first three weeks of calving, ensuring that heifers are as close in age as possible. This strategy allows for more targeted breeding, reducing the number of animals that need to be served while maintaining genetic progress.
Cows that are equally fertile but lower-yielding can be bred with beef sires, which helps optimize the use of resources. Piers notes that this approach enables farmers to be more selective, potentially breeding with dairy semen for three and a half weeks.
Challenges and Opportunities
Herd culling due to diseases like TB or Johne's can slow down both production and genetic progress. This makes it even more important to focus on breeding the right cows when the selection pool is smaller. With the right tools and strategies, farmers can continue to improve their herds while adapting to changing market demands and environmental constraints.
Post a Comment