Director column

IBC director's monthly column featured in Cattleman Magazine. Archives
	February 2026 Vitamin and Mineral Nutrition of the Late Gestation Cow By training, feedlot nutrition is my area of focus but I have a passion for all aspects of nutrition as it relates to cattle production regardless of if it is growing-finishing cattle or breeding stock. Being February, we are in the heart of winter and have only the joy of looking forward to warmer weather and calving season that is right around the corner. So, this is the perfect time to think about late gestation cow nutrition and the impacts it has on this year’s as well as next year’s calf crop. By no means do I want to overshadow the importance of protein and energy for maintaining cow body condition in late gestation cows. Maintaining cow body condition is of primary importance to colostrum yield, calf vigor, and readying the cow to re-breed. However, taking the next step and focusing on vitamin and mineral nutrition of the late gestation cow is important to attaining the next level. It is common practice for cattle producers to feed a calving-breeding mineral to cows during late gestation and early lactation. These supplements usually have increased vitamin and trace mineral concentrations and may include more available organic mineral sources. The question of "what value does this bring to my herd?" often is asked. Below are things to consider when selecting a vitamin-mineral supplement for late gestation cows. Phosphorous. Phosphorous is an essential mineral in the cow diet and impacts reproduction, milk yield, growth, appetite, and bone strength. Depending on the operation, a cow’s base diet can be composed of only grass or legume forage which are deficient in phosphorous and a supplemental source is needed. Other operations incorporate grain, co-product, or corn silage which supply phosphorous and less supplemental phosphorous is needed. It is important to keep sufficient phosphorous to meet the cow’s needs for reproduction and lactation but over supplementation is expensive and can have environmental challenges. Trace Minerals. Copper, Zinc, Manganese, and Selenium are low in milk and cow base diet feeds. Fortunately, for nutritionist these minerals impact both cow reproduction and immune function impacting in both cow and the neonatal calf. Trace minerals have demonstrated roles in cyclicity, ovulation, and conception rates in the female and testicular development and semen quality in the male. If using natural pasture mating, the bull and cow have access to the same mineral benefiting both male and female aspects of reproduction. In general, trace minerals cross the placenta and accumulate in the fetal tissues during gestation. Because milk is low in trace minerals, neonatal calves live on these tissue stores until they begin eating supplemental mineral on their own. Calves are born with a naive immune system and acquire immunity by encountering disease and mounting an immune response. Trace minerals have roles in antibody production, immune cell function, and development of the organs that produce these disease-fighting cells. Trace minerals are critical to the ability of the neonatal calf to fight disease early in life and having sufficient accumulation in fetal tissues in utero is important. Vitamins. The B-vitamins have roles in cattle immunity and are produced during rumen microbial fermentation so they are not routinely included in a vitamin supplement. We assume that cows get sufficient vitamin D through sunlight exposure. However, fat-soluble vitamins such as vitamin A and E are included because the cow cannot produce them. Vitamins A and E have demonstrated benefits to both male and female reproduction and immunity. Vitamin A is involved in sperm production and lessening the incidence of fetal reabsorption. Vitamin E lessens the incidence of retained placenta, embryonic death, and cystic ovaries. Vitamins A and E also have been linked to less susceptibility of bacterial and viral infection, fewer weak calves, and less calf mortality. Vitamin A has specific links to lessening respiratory disease; a leading cause of death in calves. Calves are born with low Vitamin A stores and consumption of colostrum and then milk are the best way to get vitamin A into the calf as it is associated with the fat component of milk. Providing the cow sufficient vitamin A, pre-calving as colostrum develops and through lactation ensures it is available for the cow to deposit in her milk. Vitamins A and E also have been linked with less incidence of uterine and mammary infection. In addition to meeting a cow’s energy and protein requirements in late gestation, ensuring the cows have access to a good quality vitamin and mineral supplement 30-60 d pre-calving through early lactation is critical for calf survivability and cow re-conception. Vitamin and mineral supplementation is an expense but when one considers that the supplemental vitamin-mineral is impacting the survivability of this year’s calf and the conception of next year’s calf crop as well as maintaining the cow, the cost is more easily justified. The IBC at Iowa State University serves as the university’s extension program to cattle producers. Our center comprises a team of faculty and staff from the College of Agriculture and Life Sciences, the College of Veterinary Medicine and Iowa State University Extension and Outreach. We work together to develop and deliver the latest in research-based information to improve the profitability and vitality of Iowa’s beef industry. If you’d like to be notified of updates on progress of research projects or programs that might be coming to your area, please subscribe to our “Growing Beef” newsletter by following the link on our website, www.iowabeefcenter.org. If you have a question, use our “Ask our Experts” link. Also, feel free to call us at 515-294-BEEF or email us at beefcenter@iastate.edu. You can follow @iowabeefcenter on Facebook, X, YouTube, and Instagram.

IBC director's monthly column featured in Cattleman Magazine. Archives

February 2026

Vitamin and Mineral Nutrition of the Late Gestation Cow

By training, feedlot nutrition is my area of focus but I have a passion for all aspects of nutrition as it relates to cattle production regardless of if it is growing-finishing cattle or breeding stock. Being February, we are in the heart of winter and have only the joy of looking forward to warmer weather and calving season that is right around the corner. So, this is the perfect time to think about late gestation cow nutrition and the impacts it has on this year’s as well as next year’s calf crop. By no means do I want to overshadow the importance of protein and energy for maintaining cow body condition in late gestation cows. Maintaining cow body condition is of primary importance to colostrum yield, calf vigor, and readying the cow to re-breed. However, taking the next step and focusing on vitamin and mineral nutrition of the late gestation cow is important to attaining the next level.

It is common practice for cattle producers to feed a calving-breeding mineral to cows during late gestation and early lactation. These supplements usually have increased vitamin and trace mineral concentrations and may include more available organic mineral sources. The question of "what value does this bring to my herd?" often is asked. Below are things to consider when selecting a vitamin-mineral supplement for late gestation cows.

Phosphorous. Phosphorous is an essential mineral in the cow diet and impacts reproduction, milk yield, growth, appetite, and bone strength. Depending on the operation, a cow’s base diet can be composed of only grass or legume forage which are deficient in phosphorous and a supplemental source is needed. Other operations incorporate grain, co-product, or corn silage which supply phosphorous and less supplemental phosphorous is needed. It is important to keep sufficient phosphorous to meet the cow’s needs for reproduction and lactation but over supplementation is expensive and can have environmental challenges.

Trace Minerals. Copper, Zinc, Manganese, and Selenium are low in milk and cow base diet feeds. Fortunately, for nutritionist these minerals impact both cow reproduction and immune function impacting in both cow and the neonatal calf. Trace minerals have demonstrated roles in cyclicity, ovulation, and conception rates in the female and testicular development and semen quality in the male. If using natural pasture mating, the bull and cow have access to the same mineral benefiting both male and female aspects of reproduction. In general, trace minerals cross the placenta and accumulate in the fetal tissues during gestation. Because milk is low in trace minerals, neonatal calves live on these tissue stores until they begin eating supplemental mineral on their own. Calves are born with a naive immune system and acquire immunity by encountering disease and mounting an immune response. Trace minerals have roles in antibody production, immune cell function, and development of the organs that produce these disease-fighting cells. Trace minerals are critical to the ability of the neonatal calf to fight disease early in life and having sufficient accumulation in fetal tissues in utero is important.

Vitamins. The B-vitamins have roles in cattle immunity and are produced during rumen microbial fermentation so they are not routinely included in a vitamin supplement. We assume that cows get sufficient vitamin D through sunlight exposure. However, fat-soluble vitamins such as vitamin A and E are included because the cow cannot produce them. Vitamins A and E have demonstrated benefits to both male and female reproduction and immunity. Vitamin A is involved in sperm production and lessening the incidence of fetal reabsorption. Vitamin E lessens the incidence of retained placenta, embryonic death, and cystic ovaries. Vitamins A and E also have been linked to less susceptibility of bacterial and viral infection, fewer weak calves, and less calf mortality. Vitamin A has specific links to lessening respiratory disease; a leading cause of death in calves. Calves are born with low Vitamin A stores and consumption of colostrum and then milk are the best way to get vitamin A into the calf as it is associated with the fat component of milk. Providing the cow sufficient vitamin A, pre-calving as colostrum develops and through lactation ensures it is available for the cow to deposit in her milk. Vitamins A and E also have been linked with less incidence of uterine and mammary infection.

In addition to meeting a cow’s energy and protein requirements in late gestation, ensuring the cows have access to a good quality vitamin and mineral supplement 30-60 d pre-calving through early lactation is critical for calf survivability and cow re-conception. Vitamin and mineral supplementation is an expense but when one considers that the supplemental vitamin-mineral is impacting the survivability of this year’s calf and the conception of next year’s calf crop as well as maintaining the cow, the cost is more easily justified.

The IBC at Iowa State University serves as the university’s extension program to cattle producers. Our center comprises a team of faculty and staff from the College of Agriculture and Life Sciences, the College of Veterinary Medicine and Iowa State University Extension and Outreach. We work together to develop and deliver the latest in research-based information to improve the profitability and vitality of Iowa’s beef industry. If you’d like to be notified of updates on progress of research projects or programs that might be coming to your area, please subscribe to our “Growing Beef” newsletter by following the link on our website, www.iowabeefcenter.org. If you have a question, use our “Ask our Experts” link. Also, feel free to call us at 515-294-BEEF or email us at beefcenter@iastate.edu. You can follow @iowabeefcenter on Facebook, X, YouTube, and Instagram.