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How Well Do You Know Your Heifers - March 2020

How Well Do You Know Your Heifers

Let’s do a quick test. How quickly can you answer the following questions about your herd?

  • How much milk are you averaging per head per day?

  • What is your bulk tank SCC?

  • How many cows are being treated for mastitis?

  • What is your average days open?

Most likely you probably knew some of these answers off your head or if not, you quickly knew where you could go to find the answer. Now how about these questions?

  • What is your mature cow weight?

  • How many heifers have been individually treated for disease at different stages of life?

  • How big are your heifers when you start breeding them?

  • Are your springers 95% pre-calving or 85% post-calving of their mature weight?

Did it take you a little longer to answer these questions, if you could accurately answer them at all? That’s likely because we don’t tend to measure and monitor these kinds of health and growth parameters like we do in the adult herd. Though these, and similar questions, are important to track and know to help raise successful replacements for your herd.

You’ve likely heard that calves should double their birth weight by the time that they are weaned. How do you know if they are doing that if we don’t know how much they weigh when they are born or when they are weaned? If they aren’t doubling their weight in that time, we need to find out why. Twenty-five percent of a heifer’s future milking productivity is determined in the first 42 days of life, so getting them off to a good, healthy start and feeding them to their growth potential has tremendous effects on profitability both now and in the future.

Ideally, we want heifers to be calving in and joining the milking herd somewhere between 21 and 25 months of age. Research has shown that heifers that freshen in this age window tend to be more productive than animals that freshen in outside of that window. But what age your heifers first freshen isn’t the only important thing. Within 2-3 weeks before a heifer freshens, she should be about 96% of her mature hip height and 95% of her mature body weight and 85% of her mature body weight AFTER freshening. To hit these ages and weight targets, we need to make sure that they are reaching an ideal weight before we breed them. Whatever your goal is for age at first calving for your heifers, your first goal should be making sure that they are at least 55% of mature body weight when you start breeding. Seventy-five percent of a heifer’s growth, including frame and structural growth, happens by the time heifers reach 12 months of age. If heifers haven’t reached at least 55% of their mature weight by the time they become pregnant, you’ll end up with heifers freshening in that are undersized. Alternatively, if you try to play catch-up before calving, this typically results in over-conditioned heifers at calving time, both of which can lead to issues with dystocias and early culls.

When we talk about mature weight, you shouldn’t take what the average Holstein or Jersey weighs and base your weights off that. Your animals may be bigger or smaller than those numbers. To find out what benchmarks you should be setting for your heifers, you should know what YOUR average mature cow weighs. To find out, weigh or use a weight tape on some of your cows that are in at least their third lactation and milking between 100-200 days in milk. This will tell you the mature weight of your herd. If you have multiple breeds in your herd or crossbreds do them in separate groups, obviously. When measuring height it is better to do it at the hips versus at the shoulder. Heights can vary by several inches at the shoulders from animals that try to pull back on a headlock and give you inaccurate measurements.

Tracking health events throughout a heifer’s life is also important. A heifer that has a bout of pneumonia is more likely to not make it to the milking herd than one that remains healthy and a heifer that has multiple bouts of pneumonia is more at risk of dying before reaching two years of age. Keeping records of when an animal becomes sick, what they are treated with and how they respond to treatment can give you a lot of feedback. It can alert you to whether or not treatment protocols are working appropriately, if animals are being identified soon enough, and if an animal should be culled due to multiple treatments for disease. It can also be an indicator of facilities that need attention, hygiene issues that need addressing, or workers that need training, retraining, or a reminder of why things are done the way they are.

So it’s important to know how your heifers are growing, where they measure up to your adult herd, and how healthy they are from birth to calving. Getting periodic weights and heights throughout a heifer’s life can help to identify if benchmarks are being met. If benchmarks aren’t being met, we need to look into why that may be and address it. Things like nutrition, stocking, or facilities. Raising healthy heifers, reducing cull rates and death rates, and calving heifers in at an appropriate age AND weight can build profitability into your herd by allowing you to reduce the number of replacements to raise and improving productivity of the ones that you keep. If you have questions about how to implement monitoring your heifers, talk to your herd health vet or any of the doctors at River Valley Vet to help identify what works for you and your herd.

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