By now, we all recognize the importance of maintaining cows in adequate body condition score as they approach calving season. Targeting a body condition score of 6 at calving will enhance reproductive function in the cow, reduce the postpartum interval, enhance conception rates and condense the calving season. However, can the growth of the unborn calf be impacted by how the mother is fed during gestation? Results from recent research trials indicate that offspring performance can be enhanced simply by providing a higher plane of nutrition to the cow. While this seems elementary, the effects are not confined to the offspring while it is a calf; instead, the impacts can be detected well into the animal’s mature growth. A recent hypothesis regarding the impact of maternal nutrition on offspring postnatal growth and development has been termed “Fetal Programming.”

It has long been recognized that inadequate nutrition during gestation leads to compromised fetal development and survival. Several studies verify that larger birth weights contribute to greater offspring survival, and maternal nutrition can significantly impact fetal growth patterns. What is less understood, but is now garnering a fair bit of interest, is how improved maternal nutrition can enhance not only fetal growth, but offspring growth and development beyond the perinatal stages.

In a recent study by the University of Nebraska (Larson et al., 2009), crossbred cows were supplemented during the winter with 1 lb per head daily with a pellet containing 28% crude protein. While this seems to be a minimal supplementation program, offspring performance was improved. Cows were heavier at calving when supplemented, and calves tended to be heavier at birth. The real interesting result was the improvement in gain prior to weaning. Calves tended to be heavier at weaning when cows were supplemented with protein during pregnancy. Additionally, calves from supplemented cows continued to outperform their mates from cows not supplemented. Calves from supplemented cows performed better in the feedlot, and even demonstrated a greater marbling ability than calves from cows not supplemented. All this evidence suggests that offspring, regardless of what you do with them (retain heifers, sell bulls, etc.), and their chances of becoming top performing individuals increase substantially when the mother is fed properly during gestation.

How do you utilize this information? Analyze the forages that you feed during gestation, particularly during the last trimester. Make sure that the forages have adequate protein and energy to support the increased demands on the cow due to fetal development. If either protein or energy is compromised, supplement with a pellet or cake to make up the deficiencies. If you have questions, contact a nutritionist, your local extension agent, or the feedmill that supplies your feed. Ensuring that the cows are properly fed will result in higher body condition scores at breeding time, but also will result in higher performing offspring.

As with many aspects of cattle production, there are many unanswered questions. The impacts of genetic differences on nutrition requirements needs further study, as does the impact of environment (hot and dry versus cold and wet) on how much supplementation is necessary. The thresholds for energy and protein to elicit an impact on offspring growth and physiology will need to be determined. But for now, the good work by Larson and coworkers is strongly supportive of paying closer attention to the needs of gestating cows.

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