Why does one animal gain 4 pounds per day when a full sibling gains 2 pounds per day? Why do some calves in the herd with similar genetics start out behind and stay behind in development through their entire life cycle? Why doesn't every cow breed at the same rate of efficiency as another?
Ron Lemenager, Purdue University animal scientist, says that the answers to these and similar questions may trace back to what happens during fetal development, especially early in the pregnancy. He calls it "fetal programming," meaning that events that happen early in the pregnancy may determine certain attributes of the animal that stick with it for its entire life.
"We now think this process is a lot more important than we once thought," Lemenager says. "The environment for the cow, including her nutrition, during this period can be extremely critical."
While research is still happening in this area and researchers need more answers, Lemenager believes it's already clear that providing more nutrients to heifers and cows during the first 21 days after breeding is probably more important than most people thought.
Lemenager says research findings indicate that it may determine whether the embryo decides to continue development, or whether it is reabsorbed. If it does develop, nutrition at key periods may have more effect on some of the animal's performance traits than anyone believed before. And based on studies that have followed animals all the way to market, these traits acquired because of how the mother was fed may stick with the animal throughout its entire life.
New interest in this topic grew out of attempting to determine how to best feed DDGs, a by-product of ethanol production. This product is considerably higher in protein than other products typically included in the ration.
The settling rate for heifers and cows that are offered better nutrition and gain weight during the first 21 days after conception were found to be 13% higher in university trials compared to groups that were fed to either maintain weight, or which were actually limited so they lost weight.
One application of this finding could be very practical. It would indicate that once animals are bred and are on grass, they many need more supplementation with protein that many producers have traditionally provided.
Lemenager says that the first trimester and third trimester of the pregnancy are especially important. Many cattlemen often assume that they can get dry cows through the winter on low quality forage. Lemenager says that their own research and other studies out there indicate that especially early and later in gestation, providing enough protein may affect the performance of the calf for life.
Sometimes the effects skip a generation, he notes. It often has to do with how the mother milks, what type of fatty acids are produced in the digestive system, and how much fat is deposited in the young female calf's udder. The result may be that the mother is a good milker, her heifer calf may not be such a good milker when she calves, but the heifer in the next generation may milk well again.
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