Reinaldo Cooke, an associate professor at Texas A&M University, emphasizes the importance of proper nutrition in gestating cows to maximize a breeding program for a producer’s future success.
“Fetus depends completely on the cow for proper supply of all nutrients,” says Cooke, “including trace minerals, protein, fatty acids, etc., to support all processes that happen during fetal development.”
The proper nutrition of the cow is incredibly important to consider because it has a direct impact on the ability of the calf to be productive throughout its life, otherwise referred to as fetal programming, says Cooke.
Although the process of fetal programming begins in the first trimester, it is important to continue the program throughout the gestation of the calf, says Cooke. In order for the maximum amount of nutrients to be delivered to the fetus, the cow must conceive at a normal bodyweight and continue to gain weight throughout each trimester of the gestation period.
“The most efficient time to make cows gain weight is when they aren’t lactating anymore,” Cooke says.
Cooke says during the first trimester, a cow should receive about 4.0 Mcals a day, which is equivalent to around 30 percent more than the amount of nutrients they would typically ingest for maintenance.
A study done at Texas A&M compared fetal programming in cows with a body condition score (BCS) of either 4 or 6. Cows that started with a BCS of 4 and were supplemented to reach a BCS of 6 in the second trimester produced calves with a higher weaning weight than the cows supplemented later in the gestation period.
“It’s not about keeping (the cow) in a body condition score during gestation,” Cooke says. “It’s always making sure (the cow) is on a positive body condition score change to make sure you are delivering the maximum amount of nutrients to the calf, so the calf is well developed and is going to be productive when it’s born.”
The most effective time frame to supplement a gestating cow would be in the second or third trimesters. It is more economical to supplement a non-lactating cow than a currently lactating cow, and it can lead to greater fetal development.
One factor into proper nutrition is monitoring trace mineral amounts in the cow’s diet, Cooke says. The trace minerals included in Cooke’s study included cobalt, copper, manganese and zinc.
Cooke and his team believe a gestating cow requires a diet of 7.3 percent crude protein and 53 percent total digestible nutrients (TDN). Along with that, the ration included 0.1 parts per million (ppm) cobalt, 10 ppm copper, 40 ppm manganese and 30 ppm zinc.
However, the purpose of the study was not to question the amount of trace mineral nutrients and study the effects of mineral inefficiency but to study the potential effects of fetal programming through additional intake of trace minerals, Cooke said.
After calving, Cooke’s team also took liver samples and analyzed the button in the placenta to better understand the passage of trace minerals to the fetus. The calves were then weaned at 7 months old and were preconditioned for 45 days before being sent to a commercial feedlot.
The results of the study showed cows that were given inorganic supplements of trace minerals yielded an average of 25 more pounds in weaning weight than cows that did not receive supplemental trace minerals, and the group of cows that received organic trace mineral supplements had an average of 53 more pounds in average weaning weight than the cows that did not receive supplemental trace minerals.
“We had a much greater value of that calf because of the greater bodyweight at weaning compared to the control group,” Cooke says. “That advantage was in both inorganic and organic but, again, greater on the organic calves.”
The study resulted in the cows supplemented with organic trace minerals increasing the weaned calf value by around $70 more than the control group, assuming $1.40 per pound at the time of the completion of the study. The additional cost of the organic supplement per cow was around $3.10.
The cows supplemented with the inorganic trace minerals were valued around $32 more than the control group, with the price of additional cost per cow being $2.
Proper management and strategic prenatal supplementation are alternatives to optimizing offspring productivity, says Cooke, but the most important factor in fetal programming starts with the basics. Ensuring proper body condition score and a positive change in score throughout gestation is crucial to the success of the entire herd. 
PHOTO: Selecting for organic minerals has shown to produce weaning weight improvements in calves. Photo by Mike Dixon.
Joy Hendrix is a freelance writer currently based in Oklahoma.
