The Cow-Calf Manager
Livestock Update, October 2007
Dr. John B. Hall, Extension Animal Scientist, Beef, VA Tech
Nutrition During Pregnancy May Have Long-Term Impacts
As we move into fall, the continued drought has many producers considering how they are going to feed the cow herd this winter. Many of the recent articles from our VT Extension Beef Team have focused on feeding and culling strategies to make it through the winter on limited feed resources. Consistently, we stressed not only keeping cows full, but truly meeting their nutritional needs, and sometimes we advocated meeting nutritional needs without keeping animals full.
There are many reasons to focus on meeting nutritional needs and not just filling up cattle on junk hay. Calf vigor and survivability are affected by nutrition in late gestation. Certainly, cow body condition at calving is related to pregnancy rates during the subsequent breeding season. However, there is mounting evidence that fetal exposure to nutrients may have lifelong impacts in animals.
Nutritional Exposure During Gestation
Many research articles indicate that maternal nutrition can impact the long term health of the offspring. In women, folic acid is an important vitamin during early gestation which impacts health of the fetal central nervous system. Mounting evidence in a variety of species indicates that extremely high energy diets during gestation can lead to obesity in offspring. Finally, maternal exposure to toxic agents such as alcohol and carcinogens can lead to lifelong problems in the offspring. These effects of uterine environment on health of the offspring are called fetal programming.
Maternal Nutrition Can Affect Reproductive Efficiency in Offspring
Research in the 1980’s and 1990’s demonstrated that severe undernutrition at almost any time during gestation can alter reproductive development in domestic animals (Rind et al, 2001). Many of these studies did not follow-up on subsequent reproduction in offspring. A few studies did follow-up on reproduction in females subjected to undernutrition during mid to late gestation. The researchers reported delayed onset of puberty. So undernutrition during gestation may impact the ability of heifers to become pregnant during their first breeding season.
Recently, a study by Nebraska researchers (Martin et al., 2007) discovered that protein deficiency in late gestation resulted in heifers that had greater difficulty becoming pregnant. Heifers from dams that were protein supplemented were heavier at pre-breeding, pregnancy exam and the beginning of the second breeding season. Interestingly, heifers from protein deficient dams were the same age at puberty as heifers from the protein supplemented dams, but fewer of these fetally undernourished heifers became pregnant or calved during the first 21 days of the calving season. Therefore, in the Nebraska study undernutrition during late gestation produced heifers that were smaller and more reproductively inefficient.
What Does This Mean for Virginia Producers?
Late gestation is (or will be) a tough time for cows in Virginia this year. Fall calving cows have experienced drought during late gestation whereas spring calving herds will have limited hay and feed supplies this winter. It is very important for the long-term productivity of the herd that late gestation nutrition is adequate. Poor nutrition during late gestation will result in decreased calf vigor and survivability, and decreased cow rebreeding rates. In addition, the future reproductive potential of herd replacements may be affected.
So do we supplement protein like the Nebraskans? NO! In Virginia, energy is the nutrient that needs supplementing most often. With limited hay supplies and variable quality, energy is most likely to be deficient. Only first cutting hay that was made very late is likely to be protein deficient. The best supplements are by-products such as soy hulls, corn gluten, wheat mids, and brewer’s grains. These feeds not only contain additional energy but also contain supplemental protein incase dietary protein is slightly deficient.
Less is known about the impact of mineral deficiencies during gestation on future calf growth and reproduction. There is limited evidence that micromineral deficiency during gestation may have long-term effects (Arthington, 2006). The mineral supplementation program should not be overlooked.
Strategies for this winter’s nutrition to prevent near- and long-term reproductive health are:
Cow-calf producers that focus on economical nutritional supplementation during this tough period will be rewarded with a productive herd next spring and in years to come.
Arthington, J. 2006. Influence of Pre-partum Nutrition on Measures of Health and Productivity of Offspring. Proceedings of the 2006 Tennessee Nutrition Conference. Department of Animal Science and UT Extension, The University of Tennessee.
Martin, J. L., K. A. Vonnahme, D. C. Adams, G. P. Lardy, and R. N. Funston. 2007. Effects of dam nutrition on growth and reproductive performance of heifer calves. J. Anim. Sci. 85:841–847.
Rhind, S. M., M. T. Rae, and A. N. Brooks. 2001. Effects of nutrition and environmental factors on the fetal programming of the reproductive axis. Reprod. 122:205-214.