Extension Education: Feeding for the Future

by Chance Marshall

Cow/calf producers are constantly looking for ways to improve reproductive efficiency and herd performance. As producers move into the colder seasons, it is important to have a nutrition plan in place for pregnant cows.

Genetic improvements obviously play a big role in herd performance. However, research continues to show dam nutrition, especially during the last trimester of pregnancy also plays a large role in future herd success. 

Approximately 75 percent of fetal growth occurs during the final two months of pregnancy.

For most spring-calving operations in Wyoming, the last trimester of gestation takes place during the first few months of the year. 

During this time period, the dam’s nutrient demands are very high in order to maintain herself during winter conditions, grow the fetus and prepare for lactation. 

Hay fed during this time period often lacks the nutrients – protein and energy – required to meet these demands. Therefore, if the dam is not supplemented nutrients during this time, the development of the fetus may also be restricted.

A series of studies were conducted at the University of Nebraska comparing performance of offspring from protein supplemented dams to nonsupplemented dams. 

The results suggest protein supplementation during late gestation would not necessarily impact their own future pregnancy success but would have a lasting impact on their offspring and the operation.

Weight and performance

This research also showed steer progeny from protein-supplemented dams were heavier at birth, had increased carcass weights and had a greater percentage of grading Choice compared to steers born to non-supplemented dams. 

Heifer calves born to supplemented dams reached puberty earlier in life, grew faster and resulted in greater pregnancy rates compared to heifer calves born to nonsupplemented dams.

Impacts to feed efficiency

Other studies have shown maternal nutrient restriction affects the calf’s ability to absorb and utilize nutrients. 

Because immature ruminants do not have a fully functional gastrointestinal system early in life – the rumen is bypassed – nutrient absorption through the small intestine is critical. 

Calves born from nutrient-restricted dams during pregnancy have shown to have longer small intestines compared to calves born from dams fed their nutrient requirements. Longer small intestines generally correspond with a higher ability to efficiently absorb nutrients.

Therefore, nutrient restriction to a calf during development can program the calf to have a greater ability to absorb nutrients. 

Additionally, poor prenatal diets have been shown to hinder muscle development while increasing the rate of fat development.

Vigor and survival

Several other researchers have reported calves born to nutrient restricted dams have increased morbidity and mortality rates. 

For example, increased sickness and death rates were recorded in calves born to dams receiving 65 percent of their dietary energy requirements during the last 90 days of gestation compared to calves born to dams receiving 100 percent of their dietary energy requirements. 

Additionally, a lower percentage of calves are weaned from nutrient-restricted dams and a greater number of calves were treated in the feedlot for sickness.

Supplementing cows during late gestation does a lot more than just keep the cow in good body condition. Feeding to meet nutritional demands of gestating cows now can set future generations up for success. 

The negative long-term impacts of restricting cow/calf nutrition during this period most certainly outweigh the short-term savings in feed inputs for the year. 

Chance Marshall is a Fremont County University of Wyoming Extension educator. He can be reached at cmarsha1@uwyo.edu or 307-332-2363.