How big are your cows? That's a question I ask producers in almost every conversation. Not because I think bigger is better! Rather knowing the size of cows helps me to develop recommendations from feeding through to stocking rates and options for markets.
How much a cow needs to eat each day is driven by her weight. Saying this often seems to be quite simple and not at all surprising! I reckon its so simple, people often don't think about it properly, and more importantly, they don't appreciate how important this simple fact is for cow fertility, beef production and to enterprise profitability.
To show how intake changes, I thought I would refer to the intake chart used in the ProGraze courses.
I like this table for a few reasons. The first is that it shows how intake increases as cow weights increase. What it also shows is how much more feed cows require once they start lactating. In the case of a 500kg cow, she will need an extra 3.8kg of feed each day when she calves.
I guess 3.8kg may not sound like much, but over 100 cows, thats an extra 380kg/DM a day, or 2,660kg/DM a week.
If cows don't get that extra feed at lactation, they will lose weight. In some cases using body reserves for lactation can be an efficient option. However, if cows are in Fat Score 2 or below, they won't have sufficient body fat to really make up the difference. As a result their return to oestrus will be delayed - meaning a longer calving interval. And they will produce less milk, meaning you will have lighter and less valuable calves.
The profit driver on any beef enterprise is kilograms of beef produced per hectare. The key to this in breeding herds is to have a cow produce a live calf every 12 months.
Based on the intake chart above, we can do some quick comparisons between the requirements of 500 and 600 kg cows (based on a mob of 100 head).
The daily intake for 100hd of 500kg cows would be 690kg/DM.
This compares to the intake of 100hd of 600kg cows. They would need 840kg/DM a day.
The difference between the two is 150kg/DM. In practical terms this could mean either you could run around 20 more 500kg cows or more likely you would be probably running a smaller herd of 600kg cows. Less cows will mean less calves and therefore less profits.
If you did try to run the same number of larger cows you would have to be prepared to provide supplementary feeds to meet their daily requirements if your pastures were lacking. Doing this will also erode the profits of the enterprise. However without feed, your cows will be less fertile and productive.
As with any of these questions, the size of your cows should be balanced against your environment and your markets. If you have the pastures and the market options for moderate size cows, then you should be using those resources to improve your productivity. But just remember, bigger cows don't always give you the most flexibility when the season gets touch or your market specifications change.
Its a simple thing, but knowing how much your cows weigh lets you know how much they need to eat and to be productive. Know this, and you can start to manage your herd to be productive and profitable.
If you want some advice or to look over your cows, don't hesitate to get in touch. Often a second opinion can make the evaluation process a lot clearer for you.