It’s that time of year, when you will see lots of articles about the importance of feed testing.
I would certainly agree that feed testing is an important step in planning winter feeding programs for our cow herds. However, it is just the first step of the process. We need to take the information from the feed tests and combine it with other data to adequately plan for our winter feeding programs.
What other information do we need?
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First, we need to have an accurate estimate of the average mature weights of the cows in our herd, as well as their body condition score. This may seem like an easy request, but the fact is many producers don’t have easy access to scales and often dramatically underestimate their mature cow weights.
Accurate body condition scoring requires a hands-on assessment rather than a crude visual assessment. All of our estimates for dry matter intake, protein and energy requirements require an accurate estimate of the average weight of the animal and their body condition score. Without an accurate estimate of these values, we can’t make the best use of our feed testing results.
Secondly, we need to have an accurate estimate of the weights of various baled forages and the quantity of bales available.
We often rely on crude estimates here, as well, and if there is an opportunity to weigh bales, we should definitely record those weights. This inventory will allow us to plan our winter-feeding program more accurately and determine if we need to access additional forage or supplemental feeds.
You will also need to have an estimate of the amount of feed that is wasted. A commonly stated rule of thumb is that if you can see feed on the ground after feeding, then you have at least 15 per cent wastage.
Don’t forget to water test as well. Water quality can have a significant impact on issues such as dry matter intake and mineral absorption.
It’s also important to get some information about the amounts and type of mineral being fed. Keep track of when you put mineral out and how quickly it disappears so that you can estimate the average consumption per cow.
Eventually you are going to have to create some rations on paper.
You will often need at least three rations for the breeding cows, depending on how you use grazing resources and the timing of your calving season: a mid-gestation ration, a late-gestation ration and a lactating ration (post calving).
Your local nutritionist, livestock extension specialist or veterinarian may be able to help you with these, or you can use CowBytes software or some of the other basic calculators that are available through Beefresearch.ca on the Beef Cattle Research Council website.
In the last few years, I’ve started to feel more strongly about the importance of determining cows’ mineral status as a component of a ration balancing program.
It is very difficult to determine the impact of all of the different mineral interactions that can potentially occur.
For example, if your feed or water is high in sulphates, copper can be tied up in the rumen and not absorbed properly.
High molybdenum levels can also result in copper being tied up and poorly absorbed.
Even if we feed test, it is almost impossible to calculate these types of interactions accurately, and the only way to know if you need to change your mineral program is to test cows to determine their mineral status.
This can be done by asking a veterinarian to submit liver samples or blood samples from a few cows to the diagnostic laboratory. This could be done in the early part of the winter-feeding period and/or just before the breeding season begins.
Liver biopsies are not difficult to do and are probably the ideal way to determine the herd’s copper status. However, if you aren’t comfortable with having live biopsies done, blood samples are still quite useful.
If the blood copper levels are deficient, then the cows are truly deficient and have probably used up most of their liver copper stores already.
I’ve seen many infertility cases occur in beef cow herds where we believe the primary reason is due to low copper levels. Evaluating your herd’s mineral status can allow you to see if you need to change your supplementation program or if you need to add an injectable mineral supplement to improve your herd’s status prior to breeding.
Feed testing is an important component of planning a winter-feeding program, but it is definitely only the first step. You are going to have to take this information to create on paper various rations for different production stages of the herd. You are then going to have to adapt that ration into a real-life feeding situation.
We are feeding groups of cows and not individuals, and you have to translate numbers such as grams of mineral per cow per day to bags of mineral per week.
Finally, it is always important to monitor factors such as body condition and intake and adapt as necessary.
Not everything goes as planned, and environmental challenges such as extreme cold will also need to be accounted for and the ration adjusted accordingly.
John Campbell is a professor in the department of Large Animal Clinical Sciences at the University of Saskatchewan’s Western College of Veterinary Medicine.
