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FAT CONTENT IN COW'S DIET IMPORTANT DURING GESTATION

by: Heather Smith Thomas

Cow nutrition is dependent upon adequate energy, protein, vitamins and minerals in a balanced diet, but recent research is also showing that during the last part of gestation the fat content of a cow's diet is also very important; especially in terms of rebreeding. A number of studies have been done on this, and are still ongoing. Research on fat in the diet has been done at North Dakota State University, Tom A&M, the USDA Livestock and Ranch Research Laboratory at Miles City, Mont., and at the University of Missouri Forage Research Center at Linneus, Mo.

Chris Zumbrunnen, regional livestock specialist at University of Missouri, became interested in this subject a few years ago after seeing an article in one of the beef publications with some results of a project done by Bob Bellows at Miles City.

"What caught my eye was that he reported calves born to cows that had been fed high fat levels late in gestation were better able to maintain their body temperature. The reasoning is that the calves have higher levels of brown adipose tissue surrounding their internal organs, which allows them to maintain body temperature for a longer period of time when suffering cold stress. The thing that got me interested in this is that in our area we have wet conditions during calving; when baby calves hit the ground in March they usually splash. It's usually muddy, and this is a stress factor. You start thinking, what's an extra hour or two worth, in a calf's ability to handle that stress? It could be the difference between saving the calf or not," says Zumbrunnen.

"The Montana study used safflower seed, which is not an option in Missouri. So we started looking at whole soybeans. The fatty acid profile between the beans and the safflower seeds is very similar, and the first year we did this, the beans were inexpensive (mid $4 range), so we decided this would be something we'd like to look at. In the two years we've run the study, we've never seen a difference in calf survivability; but we haven't lost any calves, either; we had mild weather those years, and super people at the research farms (good management)," he says.

Dr Bellows also reported an increase in first service conception rates, and the thing that's hardest to sell to producers about this is that all the feeding that's shown good results has been precalfing. We started feeding fat (soybeans) 45 days prior to calving and stopped it after the cow calved, yet we were still consistently showing a 14- to 15 percent increase in first service conception rate. That's compared to a corn gluten and soybean meal (soybeans with the oil extracted) control diet. The two groups of cows were getting equal protein and equal energy, and the only difference was in the fat levels," he says.

"From what little other work that's been done on this, we feel that since it's a vegetable fat, this is probably the key to what we need to be looking at," says Zumbrunnen. "Our idea with using the whole soybeans was partly because bypass protein was all the rage at one time, and we thought we might be able to get some of those fatty acids through the rumen, using soybeans.

He questions the validity of supplementing a mature cow on a regular basis. "If we're to that point (barring a hay shortage or some other feed crisis) I question whether it's economical. People can't afford to supplement cows; they need cattle who can perform on what their farm or ranch grows. But where this type of supplement really works is for two- and three-year-olds, especially in this fescue area where we have most of our fall calving cows. It cost us a quarter a day to feed them, both winters we've done this, and I think on bred heifers and second calvers, that's money well spent. Once you've got the development cost in a heifer, you have too much money tied up in her to lose it. You need to make sure she doesn't come up open," he says.

"We had a set of cows this year at the University's Thompson Farm near Spickard, Mo. -- 100 mature cows (ages 5 to 12) in excellent body condition (BCS 6 was the low end) -- and we were set up to run the project and went ahead with it even though we all questioned whether these con needed any supplement. David Patterson (the person in charge of Missouri's Show Me Select Replacement Heifer Program) did the AI work. The cows were in two groups: one on whole soybeans and the other on their regular diet (gluten and soybean meal). We used the same bull, same semen tanks, same technician, everything was identical," says Zumbrunnen.

"Patterson got an 87 percent conception rate (first service) on the soybean cows and 63 percent on the control cows, which is a 24 percent difference. I wasn't able to be there when they got the results, but I got a phone call that evening from Patterson and he was just beside himself and really excited. That kind of variation might have been the outside range, but even an increase of 14 to 15 percent on first service, or a 7 percent increase in overall pregnancy rate, would pay off."

The cows were in the 1,300 pound range, and received 3 pounds of whole soybeans daily per cow. "With the hay we were using, and the analysis on the hay that puts us right at five percent fat in their diet" according to Zumbrunnen.

"We have seen good results feeding fat somewhere between 30 to 45 days prior to when the cows are supposed to start calving. We get a little better results going 45 days than we do at 30, which is the bare minimum. Our projects and results show that if you quit feeding the fat when they calve, you still get these responses."

"If you feed it after they calve, it's not as beneficial. The first year we ran this project, we fed some after calving (started feeding the fat when they calved). Not only did we drop body condition score on the cows more by supplementing them, we also didn't see anywhere near the first service conception on the cows as we did when feeding it up until calving."

The interesting thing about it when they calculated calves' average daily gain was that they got a little higher gain on the calves from cows fed fat after calving. "So I think what we were doing was increasing the cows' milk production," he says. The cows were putting the extra nutrients into their milk instead of toward their own body condition. "Yet when we took those figures on out to weaning, there was no difference in the calves; they all evened out. But there was a 60-day period in which the calm picked up an extra 0.2 to 0.25 lbs. of daily gain."

People have asked Zumbrunnen if feeding fit increases birth weights. "We have increased our birth weight only about 3 to 4 lbs. on the cows we fed fat to prior to calving. One of the concerns I hear from a lot of people is that supplementation prior to calving will increase birth weights, but we had no increase in dystocia. The calves went from 87 lb. average birth weight to 90 lbs., which is not bad."

He tells people that with soybeans down to $4.25, they need to think about using fat with the two- and three-year-olds (first and second calvers). Starting 45 days before calving, they can be fed whole beans (3 pounds for the heifers, 3.5 pounds for the young cows).

"We've had a lot of interest in this project. In early December, we started another project on developing heifers. We'll put 200 heifers on different bean diets and see if we can get some kind of response on open heifers with the Show Me Select Program here in this state. If we can tie it in and pick up that kind of increase in first service conception on heifers, it would be fabulous. I think with all the money ranchers have tied up in heifer development; that even if beans got up to $8 again someday it would still pay to feed the bred heifers, if you can get this kind of increase in breed back," he says.

People used to think they needed to cook the beans, but he says raw soybeans work fine for cows. "For hogs, you do have to heat soybeans to destroy a trypsin-inhibiting agent; hogs don't digest whole soybeans as easily as cows do. We use bin run beans and they may have cocklebur or whatever, but we can use them right out of the bin."

People also question digestibility when they see a few whole beans in the manure of cattle, but Zumbrunnen points out this is similar to seeing whole shell corn coming through a feedlot steer; the corn has still been digested and very seldom sprouts. There is some skepticism also about palatability; some people think cattle won't eat soybeans. He says, "We have seen very few cows that refuse to eat whole soybeans. We had a couple of cows that wouldn't eat beans but when we sorted them off and offered them corn, they wouldn't eat that, either."

The other thing he's heard people say is that soybeans will kill cows. "Usually where this idea comes from is a case or two in which a trucker pulls into a grain bin and loads up beans, and then leaves without cleaning up the mess around the auger. Some cows get in there and maybe clean up 200 pounds of beans, and it kills them. But if it had been corn, it would have killed them, too. Letting a cow overeat that much is poor management."

He says cows love the beans. "We got some money from the Soybean Merchandising Council to do this project, and that was one of their questions - to determine palatability. My kids had a few cows that year and we took a set of bred heifers that had calved, and put feed bunks around their pen. We'd put corn in one bunk and beans in the other, and move them around. We got pretty creative about switching them around, and the cows would always go find the beans, to eat them first. They'd eat the corn, too, of course, but given their they'd go to the beans first."

He says, "I think for this part of the country, and for any region where soybeans are available, there is a lot of potential for feeding them to two- and three-year-old cows. It's really exciting and we are in the process of putting together the results of our projects for the Journal of Animal Science."

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