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Fetal programming considerations adds dollars to ranching operations

by Wyoming Livestock Roundup

Riverton – In the last several years, fetal programming has emerged as a top consideration for raising the most productive, profitable cattle, but Ray Ansotegui, a retired animal science professor and beef nutrition specialist from Montana State University, says the ideas behind fetal programming extend back to the mid-1940s.

“Realistically, we knew about fetal programming in 1944-45, only it was in people,” Ansotegui explained during a session on Fremont County Farm and Ranch Days’ Feb. 7 session. 

Ansotegui explained, during those years, the Nazis took over Denmark, and a famine ensued. A number of pregnant females lived in Denmark during that time, and their children exhibited a number of problems, both at birth and throughout their lives.

“Fetal programming is a big deal in cows today, but we should have figured more about it then, looking at results from human development,” he said. 

Explaining programming

Ansotegui defined fetal programming as the concept that a maternal stimulus or insult at a critical period of fetal development can have long-lasting impacts on offspring. The idea of fetal programming is supported through numerous studies. 

“Fetal development may become a problem in the early developmental stages,” he said. “Insults may be later in gestation can affect growth, health and reproduction.”

Many different research projects have shown protein supplementation positively affects calf health in a variety of aspects, including weight, reproductive efficiency and carcass quality. 

“Negative nutrient environments can also cause a response,” he added, noting that increased neonatal mortality, death soon after birth and a variety of intestinal, respiratory and metabolic disorders, among other challenges may occur. “All of these things are affected, but it’s at a different stage of pregnancy that impacts result.” 

“Increased sickness and death comes from calves born to heifers receiving 60 percent of dietary energy compared to heifers receiving 100 percent of dietary energy needs,” Ansotegui noted adding heifers receiving their full dietary energy requirements also saw calves with increased birth weights. “This data comes from original studies from Larry Corah.” 

Nutrient partitioning

Understanding fetal programming begins with nutrient use by the cow. 

“As we look at nutrient partitioning in the cow, when she can’t get enough feed to meet her needs, what does she give up first?” asked Ansotegui. “She first sacrifices excesses reserves or fat. The second thing she gives up are estrus cycles and the initiation of pregnancy.” 

Then, the cow forgoes additional energy, followed by lactation and body reserves. 

“Young cattle lose growth, then activity,” he said. “Then, when it gets serious enough, they quit breeding.”


Nutrient deficiencies at different stages of gestation impact the developing calf differently. 

“In early gestation, we need adequate transfer of nutrients to the fetus,” he said. “A little later in gestation, deficiencies influence organ development, muscle development, post-natal calf development and carcass characteristics, and we see impacts to reproduction and health as we go later in pregnancy.”   

Early gestational deficiencies impact the nutrition received by the fetus. 

“One of the first developments is the development of the placenta on the uterine wall, which hooks the calf up and provides it nutrition,” Ansotegui said, noting that impairment of nutrition at this point can result in inability to transfer nutrition properly or transfer enough vitamins and minerals. 

“We see liver development as early as five days, followed by development of other organs,” he commented. “Testicular development in males starts as early as 45 days after conception, and ovarian development is 50 to 60 days after conception. Ovarian reserves in females are developed around day 80.”
Studies have shown that progeny of heifers fed only 55 percent of their nutritional needs had a lung weight of only nine pounds, compared to the lungs of their contemporaries from heifers fed at their full requirement, which weighed 14 pounds. 

Later impacts

Mid-gestational impacts reduce muscle fiber networks, and late gestation nutritional deficiencies reduce muscle fiber and the formation of intra-muscular adipose, or the fat that results in marbling. 

“If they don’t have intra-muscular adipose developed, the calves will have much-reduced marbling later in life,” Ansotegui said.

“What all this data really points out is, we can screw this calf up at any part of his growth if the dam is nutritionally deficient at any point,” he emphasized.

Inside one study

To demonstrate his point, Ansotegui looked at a study by Martin in NorthDakota. 

“Martin found differences in birth weight between supplemented and non-supplemented groups,” he said. 

For example, at weaning, Martin found supplementation resulted in an increase of 15 pounds at weaning and 20 pounds at a 205-day adjusted weight. 

At breeding, the 88 percent of heifer calves from supplemented dams conceived at their first service, while only 45 percent of heifers from non-supplemented dams conceived. Further, by the end of breeding 94 percent of heifers from supplemented dams conceived, while 73 percent of heifers from non-supplemented mothers were pregnant. 

“The other thing that’s scary here, however, is calving difficulty,” Ansotegui said. “In the supplemented group, 69 percent calved unassisted, but only 38 percent of non-supplemented heifers calved unassisted.”

“We have to keep in mind when we look at this data that these heifer calves spent every day of their lives side-by-side,” Ansotegui emphasized. “The only thing that was different was whether their mothers were supplemented before they were born.”

Saige Albert is managing editor of the Wyoming Livestock Roundup and can be reached at

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