FEEDING FOR BREEDING by Mike Mehren Ph.D.

FEEDING FOR BREEDING
BY MIKE MEHREN

As we approach the breeding season for spring calving cowherds, it might be worthwhile to review some of the research regarding causes for open or late-calving cows. We will specifically focus on the time between calving and breeding. There are many factors that affect whether a cow breeds in a timely manner. Some are environmental; such as a drastic change in the weather. A change to hot or cold weather causes animals a certain amount of stress. Management would also be closely related to a good conception rate or a poor one. This might be seen as not enough bulls, bulls in poor body condition or bulls not given a breeding soundness exam, Cow and heifer body condition plays a huge role in successful breeding. We could call this a management problem...not feeding enough, or feeding enough pounds, but not enough nutrients in the feed (typically I see this as feeding a lot of straw with nothing but a protein or mineral supplement). The heifers may not have been separated from the mature cows and can’t compete for all of the feed they need. Wormy cows won’t gain weight because of the damage done to the intestinal tract and subsequent lack of nutrients. Cows rubbing and continually bothered by lice won’t gain normally either. Diseases that affect the reproductive tract of bull or cow are factors. Research studies indicate that heifers must reach a certain size (60-65%) of mature weight in order to breed successfully. Last, but certainly not least in our hearts, is good old everyday nutrition.

Too often we look for a silver bullet to solve breeding problems. There could be a silver bullet if your feed had everything the cow needed except copper or some other single nutrient. If that happened, we could have chelated copper or copper sulfate, or copper chloride added to the mineral mix. We could also dose the cows with a copper oxide bolus. However that’s pretty unlikely in our part of the world. Most of the time, breeding problems are a combination of factors. Let’s pick on minerals for a moment. I’ve never seen a feed analysis from a forage, grain, or by-product that was adequate in every mineral. To compare the feed you have to what an animal needs, a table from the Nutrient Requirements of Beef Cattle is used. If you’re so inclined, a copy of this publication can be purchased from the National Academy Press. It can be found on the internet or through a book dealer. For instance, grain has a substantial amount of phosphorus, but very little calcium. On the other hand, alfalfa has a lot of calcium and relatively little phosphorus. This is also true of protein; grain has some while alfalfa has an abundance. This is one of the reasons these two feeds compliment each other so well. Many of our grasses and legumes are high in iron and low in zinc, copper, and selenium. This is one of the reasons I prefer mineral mixes that are designed for the Pacific Northwest, rather than something formulated and made in the Midwest and sold out here. Those products often lack the extra copper, zinc, and selenium that our cattle need. The following are some of my recent experiences in feeding for breeding.

A group of really good black heifers had failed to breed as expected. . When the bulls were turned in, a very low percent of the heifers bred. A veterinarian was called in, and he determined that there was no disease causing the problem. He also noted that the body condition of the heifers was a little less than past years. When the manager was reviewing his notes about the herd, he noticed that the bulls were scheduled for a fertility exam, but that something happened and they never got tested. He also reported that he used a mixture of mature bulls and yearling bulls. Since feed costs were so high, he had reduced the amount of grain that was normally fed to the heifers. I got involved after the fact; the bulls had been moved, and the heifers looked great. In fact, they were constantly riding while we stood and watched them. The manager decided to separate the heifers into smaller breeding groups; fertility test the bulls he would use, and then not put mature and yearling bulls in the same group. The result was that virtually every heifer bred during her first cycle. In this case three small omissions combined to cause a big wreck. Feed heifers enough to gain about 1.5 lb/day. Semen test all bulls before each breeding season. Don’t use a combination of mature bulls and yearlings in a confined breeding situation.

Recently we noticed a group of cows that didn’t seem quite right. We reviewed health and vaccinations and found them to be up to snuff. The cows had started calving. The cows were on a circle of corn aftermath, and had been there for quite awhile. We were feeding them about 5 lb of alfalfa along with about 15 lb of grass straw. They were being fed a mineral designed to compliment the corn fodder. We took a hard look at the corn circle and found that the cows had grazed virtually all of the leaves, husks, and cobs. All that was left was stalks. Based on this finding, we decided to change our supplement program. We began feeding a mixture of corn silage and wet distillers grain to increase both the protein and energy of their diet. As you would expect, the cows didn’t hesitate to begin eating the new feed and seemed to be quite a bit more content.

The cows in the example above were grazing corn aftermath. If feed prices continue to be high, we may have more and more corn aftermath baled. Hopefully, I will have some comments on baled corn fodder for a future column. If you have experience with baled corn stalks that you’d like to pass along, I’d be happy to hear from you. Right now, the biggest issue seems to be the amount of waste. We have tried grinding it twice before feeding, and still have some large pieces of stalk that cattle leave behind. The samples that have been analyzed have from 4 to 7% crude protein and 45-55% TDN on a dry matter basis. We could substitute straw for corn stalks and the figures would be identical.

I think the biggest issue will be counting on stalks to provide most or all of the nutrition for a cow when she gets close up to calving, or after she calves. It won’t work...no matter which super-duper supplement you feed! The recent cold weather and snow have not helped matters. Cold weather requires more energy to keep the cows alive and well. If extra energy isn’t fed, then the cow will draw on body reserves of fat to provide that energy. A cow with body condition of 4 or less, won’t have the fat reserves to draw on, may have trouble calving, and will certainly not come into heat in time to calve at the same time next year.

Research on this subject has provided some excellent guidelines. Dr. Karl Hoppe, of No.
Dakota State Univ. Extn Svc. showed what happened to pregnancy at different feeding levels after calving. He reported the pregnancy rates 60 days after calving.

Energy (TDN) in feed	Gain,	Percent Pregnant at 60 days
After Calving	lb/day	Moderate Flesh	Thin cows
Hi	1-2 gain	92	92
Moderate	none	88	92
Low	1-2 lb loss!	85	68
Low –Flush 14 day before and 30 days after bulls turned in	1-2 lb loss!	91	84

This data shows that cows can be kept on a pretty low plane of the nutrition between calving and breeding and a high percent can still get pregnant IF they are fed a ‘flushing’ ration. Look how poorly thin cows bred back when they were fed the poor quality ration only. Normally, young spring grass serves as a flushing feed. However, if a cold wet spring follows your calving, and you expect the cows to calve within a year, then you need to go to ‘Plan B’. In this study, the cows were fed about 11 lb of grain and free choice corn silage as a flushing ration. You may not be able to feed something like that to your cow herd, but at least be aware that the World’s Finest Supplement, be it liquid, dry cake or pellet, or lick tub plus straw, grass hay, or dry range with a hint of green feed will NOT serve as a flush for thin cows. Hay and wet or dry distillers grains would be very effective. Canola meal from a biodiesel producer would also serve as a source of extra protein and energy.

This year’s feed prices and weather may give us a pretty harsh lesson about starving a profit out of a good cow. Feeding a flushing ration if you don’t have high quality spring grass will improve breeding success for thin cows.

Michael J. Mehren, Ph.D. is a livestock nutritionist studying the feeding habits of steelhead and salmon near Hermiston, OR. He may be contacted by Email at mehrens@eotnet.net.