SUPPLEMENT INTAKE by Mike Mehren Ph.D.

SUPPLEMENT INTAKE
BY MIKE MEHREN

Checking the intake of any kind of supplement is very important to your bottom line; since winter feed costs (or when cattle are on mature, dry range) are a large portion of the total cost. I know this has been addressed in a past column, but it is so important to cost control and performance that you’ll have to bear with me again.

A gentleman called the other day telling me that his calves were eating mineral like it was candy. He was concerned about the cost and whether they could kill themselves eating too much mineral. Here are the details. There were 100 calves; they had been weaned 2 or 3 days ago. He was putting out 25 lb (1/2 bag) of mineral and it was all gone the next morning when he returned. To calculate how much they ate, we divided 25 lb by 100 head to arrive at 4 oz/head. That’s high, but not really excessive. I asked him what the rate of intake was supposed to be. He checked the label, and found that expected intake of that product was 2 to 4 oz/head/day for cows and 1-2 oz/head/day for calves or yearlings. We decided to let them continue to eat the mineral as it was for the next week or ten days, and then if they were still eating that much, we would add salt to cut down mineral intake.

He asked what caused the higher-than-normal intake by the calves. That’s the million-dollar question. If anybody has the correct answer, I’d like to hear from him or her. Mineral and supplement intake is affected by a variety of factors. We know some of them, but not all. We can control or manage some of them, and some we just have to live with. Some of the factors that affect supplement intake follow:

Weight and age of the animals.

Kind of feed they are eating. Cattle will go from eating no supplement at all to eating quite a bit when moved from one pasture to the next. Cattle on a pasture that is lush and green will eat a different amount of supplement on that same pasture when it is dry and mature. Intake will change when cattle are moved from summer range to winter feed grounds; and again when they are moved out to spring range. I’ve seen situations where supplement intake was normal when one cutting of alfalfa was fed, but then when another cutting from the same field was fed, the cattle quit eating supplement entirely.

Location of the supplement relative to water. This can differ between summer and fall grazing. Hot summer days affect where and when cattle will graze and go to water, when compared with cool or cold days. When there is snow cover, the animals may eat the snow and not go to water, because it is frozen. They may not go near the supplement location if it is near water. When all the water sources are frozen, cattle will drink liquid supplement, which can be very dangerous if it contains urea.

Type of feeder used. We use everything from old drums, liquid tanks that are open, closed liquid tanks w/ a wheel, liquid tanks that are computer controlled, huge molasses tubs, small tubs, compressed blocks for mineral or protein, range cubes, meal forms of protein and mineral, and feeders with a tub and a wind vane, covered feeders where the animals lift the lid. Each feeding device will influence intake.

A study in Montana several years ago found that herd dominance played a huge role in which animals ate the supplement as well as how much they ate. The animals were a mixture of heifers and cows. The cows dominated the situation so well that some of the heifers never got any supplement during the study.

Nutritional status of the animal. This is complex and not well understood.

The taste or smell does not appeal to the animals at that time.

Let’s assume that all supplement manufacturers are capable of making a supplement that your cattle will eat. If anyone tells you ‘they always eat my supplement’, get them out the gate as fast as possible. Another good clue is when someone tastes a supplement and declares ‘cattle won’t (or will) eat this’. Our response to taste or flavor is very different from cattle. Most of us will agree that cattle like molasses. If you ever get a chance, take a little taste of livestock cane or beet molasses yourself. You’re in for quite a shock.

When cattle overeat or don’t eat a product, something ‘unusual’ is happening, or they may not want to eat it right then. If it was left there, they might decide to eat it next month. It may be as simple as having salt blocks out in addition to a supplement. The label states ‘feed as the only source of salt’. This means that the manufacturer believes that the salt in their product will attract the animals to eat, and also limit the amount of intake to a reasonable level. When there is other salt present, some use the supplement, and some use the salt. I’ve encountered problems when cattle were grazing alkali land and wouldn’t eat a mineral that had salt in it. Some other carrier must be used to attract the animals to the product. Sometimes we don’t put out enough feeders or blocks or whatever to give all of the animals a chance to eat some of the supplement. The older more aggressive animals push the younger and more timid animals away.

Here’s a handy little table that might help you compare expected intake with what the cattle are eating:

Intake by 100 head over 7 days. (assume bags weigh 50 lb)

1 oz	44 lb	< 1 bag	2 oz	88 lb	2+ bags
4 oz	167 lb	3+ bags	8 oz	350 lb	7 bags
1 lb	700 lb	14 bags	2 lb	1400 lb	28 bags
4 lb	2800 lb	56 bags	5 lb	3500 lb	70 bags

Sometimes cattle continue to overeat a supplement. This can usually be fixed. A liquid can have a ‘bitter’ compound added. A dry meal can have salt or magnesium oxide
added. For tubs, range cubes, and blocks the only thing that can be done is to put out enough for a certain number of days, and then not feed again until your schedule calls for another feeding. This works well for protein, but I would still limit the days the cattle aren’t fed supplement to no more than 3.

If the cattle won’t eat a supplement, the problem can be much more difficult to solve. If it’s a liquid or a meal, then something sweet or palatable can be added to the mix which will often encourage intake. Sometimes hay can be put on top of a tub or block and give the cattle a chance to smell it as they eat the hay. More often than not, the tubs, blocks, or range cubes will need to be replaced with a different formula. When there is a fall ‘green up’ the cattle may not even recognize the supplement for what it is until the grass is all dry and they re-discover it.

Cattle don’t have nutritional wisdom even though it looks like they do at times. If they were so smart, they wouldn’t eat plants with high levels of nitrates or endophytes. They wouldn’t lick old batteries and kill themselves from lead poisoning. They wouldn’t graze lupine, or eat pine needles. The only nutritional wisdom that science has identified is a craving for salt. In a very extreme case of phosphorus deficiency, animal may eat bones to supply the missing mineral. We use salt craving to get animals to eat trace minerals and vitamins that they need.

Like most of good cattle- raising, it takes skill and observation to accomplish your goals. Just choosing the right supplement is not enough. You have to make certain that the cattle eat the right amount if you hope to get a return on your investment.

Michael J. Mehren, Ph.D. is a livestock nutritionist who uses skill and scale to continue to gain weight throughout the year. He may be contacted by email: mehrens@eotnet.net.