• ZISK

Calf Considerations Part 3: How many heifers do I need to raise?

April 28, 2020


Kimberley Morrill



Growing up on a dairy farm, one of the most exciting things was finding out your favorite cow had a heifer calf, on the flip-side, tears may have been shed when you saw it was a bull…I might have also cried when my dad told me my youngest sibling was a boy. The day your favorite cow had a heifer calf stands out, it’s still exciting at 30+ years old when my brother calls to tell me we have a new heifer that goes back to Star, or Scarlett or Carla. It lets you dream about the future, a herd full of red & whites would be my ideal. While, bull calves were a hard lesson, learning that we couldn’t keep every heifer was a harder, more valuable lesson. Dad always had a list of how many cows and heifers my brothers and I owned, and if it started to get out of balance, decisions had to be made. While we were younger, selling cattle gave us a chance to save our money, invest in a new cow family, pay for a car, save for college or have some spending money. As we got older, selling animals became more and more part of a long-term business decision.   

Over the last few years heifer inventories have come under greater scrutiny for many dairy operations. It’s expensive to raise heifers, Jason Karszes (Pro-Dairy, Cornell University) has reported that the average total investment into a heifer (birth to parturition) is $2,232. As producers look at areas to reduce cost, heifer rearing becomes a target. While we can look at ways to reduce the rearing costs, we also need to evaluate – are we raising the correct number of heifers and are we raising quality heifers?

Maybe we should start with the last question…A few years ago I was working with a farm that was having a lot of calf and heifer challenges, and they were not happy with the quality of the fresh heifers. They were having a high number of sick, and dead calves, poor pre-weaning weight gains, and a train-wreck in their weaned heifer facility. After numerous farm visits, conversations, changes to calf protocols, and still being unhappy. This farm did a great job with their lactating herd, with dry cows and with crops, but calves were still a struggle. Finally, the questions was brought up – why are you raising heifers? I believe the response was “they are a necessary evil”. That day a decision was made to sell all open heifers, all future calves (bull or female) would be sold within a few days, and they would buy replacement, lactating animals only. This decision would be evaluated at future team meetings. Nearly two years later, this has been an excellent decision for this farm. The owners and employees have been able to focus on what they are most successful at doing, and they budget to purchase groups of cows as needed. While this is not an option for every farm, it is an option for some farms.

Moving onto the first question, how many heifer calves should I raise? To answer this, we need gather some herd information first.

Herd data needed: ·       Lactating and dry cow information: Herd size, Cull rate, Death rate, Age at first calving and Calving interval ·       Youngstock information: Non completion rate for heifers (sold and died), Calf mortality rate, Percent of heifer calves born.

Once we have all our numbers, we can need to do two calculations:

How many heifers are needed per year = (herdsize) x (cull rate + death rate) x (age at first calving ÷ 12) x (1 + noncompletion rate)

How many heifers will be produced in one year = (herd size) x (12 ÷ calving interval) x (percent heifer calves) x (1 – calf mortality rate) x (24 ÷age at first calving).

If heifers needed and heifers produced are within 5 to 10% you are likely raising the correct number of heifers. A 5 to 10% buffer allows for minor parameter changes, if you are a low risk taker, you may want to bump it up to 15% and monitor heifer inventories as they age. If you want to break these numbers out by how many heifers should I raise per month or even week, you can, but you also need to look at seasonality changes. Do you normally calve in a large number of cows in the spring, avoid calving in January, or August, have calf health challenges in March? These are all factors that need to be thought about before you say – “I need to calve in 120 heifers every year, so I’m only going to raise 10 heifers per month”. You also need to be thinking about changes to herd size over the next 12 to 24 months. Are you going to need more heifers, or maybe less? Now that you know how many heifer you need to raise, the next step is to develop some guidelines on how do you decide who to keep?  There are lots of options, health, growth, genetics, and even space availability…hmm…sounds like a great topic for another article.

Going through this exercise provides you will more information than just heifer needs. It makes you look at your herd data, this may spur other discussions: why is our calf mortality rate so high? How can we reduce our age at first calving? Why is our calving interval 13.5 months? Improving these parameters can in-turn reduce the number of heifers that are needed and help reduce the cost of your replacement heifer program.