Ivan Rush: Supplementation, cow condition and fetal programming
December 23, 2010
The last third trimester of pregnancy is near for most spring calving cows. Now is the time when maintaining adequate cow condition is very important. In general, most producers desire a body condition score (BCS) of 5 for cows; some feel more comfortable with a condition score of 6 for first-calf heifers.
There is little question that ample body condition is good insurance for the cows to breed-back and for calf vigor. Yet, several years of data at the University of Nebraska Gudmunsen Sandhills Laboratory have shown that mature crossbred cows with a BCS of 4 will breed back just as well as cows with a BCS of 5.
I began to believe that in some cases, enough money could be saved that it was not always economical to maintain higher BCS, when more good research – with economics – was published on the topic. Researchers at Oregon State looked at the effect of supplementing mature cows in either BCS 4 or 6. They supplemented with two pounds per day of basically a dried distillers supplement (actually supplemented 3 times per week). Cows that started the winter in higher body condition had greater overall performance over the thinner cows, but supplementation was of minimal effect in both cow and calf performance.
Cows that were in higher body condition had a $71 greater return if the calves were sold at weaning, and $130 greater return if calves were maintained through the feedlot. This was primarily due to the fact that higher BCS cows had 10 percent more calves at birth and weaning and had a much higher pregnancy rate (91 percent vs. 79 percent). Plus, calves from cows in higher body condition were heavier at weaning.
Interesting to this data, supplementation was of no benefit on the majority of important traits, suggesting that fetal programming did not occur. Although not significant, it did appear to slightly improve reproduction of supplemented cows. Calves from the thin supplemented cows were numerically higher for percent choice grade.
In the last Nebraska Beef Cattle Report (2011) two articles were published concerning late supplementation and its effect on fetal programming in subsequent calf performance. At the Gudmunsen Sandhills Lab, when cows grazing mature winter range were supplemented with a pound of a 28 percent protein supplement, it appears that, unlike the Oregon data, the fetus was “programmed” to gain more up to weaning. However, supplementation did not have any benefit on the weaning weight of the calf when fed to cows grazing corn stalks.
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This data is interesting, as the researchers, led by Dr. Rick Funston, evaluated the effect of protein supplementation on subsequent reproduction and feed efficiency of the heifer calves. Again, heifer calves from cows that were supplemented on winter range had better reproductive performance by reaching puberty earlier and having a higher pregnancy rate, while supplement had no effect when fed to cows on corn stalks. Much to my interest, heifer calves from cows that appeared to offer the fetus the lowest level of nutrients (cows on winter range with no supplement) were the most efficient in the growing phase.
Another paper in the 2011 Nebraska Beef Report was research from the Rex Ranch in the Sandhills of Nebraska which involved approximately 1,500 head of cows grazing winter range where two levels of supplements were offered for two consecutive years. Levels offered varied slightly from year-to-year, but they were approximately one pound daily of a 28 percent protein for the low-level and 2-2.5 lbs. for the high level of supplementation. Weaning weight was not affected by level of supplementation, however the first year feedlot gain was greater for steers from cows receiving the higher level of protein.
Like some of my research, when you get the answer you want, perhaps you shouldn’t repeat it. In the second year of the study, with the same design, no differences were noted due to supplements on feedlot performance. It did appear a slight improvement was made in marbling scores both years when cows were offered a higher level of supplement.
So what does all this mean? It appears that at times when certain conditions exist, it is possible that the dam will “program” the fetus to perform at a level well after birth. Because of the variation in the data, it is difficult for me to recommend feeding protein if fetal programming is the only objective. Obviously it is not the only objective, as added supplementation will add body condition to the cow, especially if the cow is thin. Most data and experience says reproduction and calf health will improve when the cow is in good body condition at calving.
If you didn’t enjoy prime rib for Thanksgiving, I hope you all can sit down to a great delicious prime rib as you celebrate Christmas with your family.