THE FLORIDA CATTLEMAN AND LIVESTOCK JOURNAL
Fetal Programming in Beef Cattle and Other Livestock Species
by Phillip Lancaster
For questions or comments regarding this
publication contact: Dr. Phillip Lancaster, University of Florida, IFAS
Dr. David Barker studied the incidence of chronic disease in people conceived or born during the Hunger Winter in the Netherlands during WWII. He observed that these people had a higher incidence of chronic disease such as impaired glucose tolerance, high cholesterol, high blood pressure, and obesity as adults than people born shortly after the war. This led to a research effort in fetal programming to determine the impact of maternal nutrition on performance of subsequent offspring in livestock.
Fetal programming is a phenomenon in which the intrauterine environment experienced by a fetus alters the expression of genes later in life, changing the phenotype of the animal. These changes are called epigenetic changes in gene expression. This means they are not changes in the DNA sequence/genetic code, rather they are changes in other parts of a DNA molecule. Epigenetic changes affect how genes are expressed, which allows an animal to adapt to its environment even after the genetic code has been set. To date, it is fully understood how management of the pregnant beef cow impacts develop of the fetus and offspring performance. Much more research is needed in the area of fetal programming before management practices can be developed to optimize fetal development in livestock production systems.
Research in livestock species has found that maternal nutrition during gestation can impact growth, carcass quality, reproductive performance, milk production, and feed efficiency in offspring. It has been known for some time that nutrient restriction of the dam during late gestation can result in low birth weight calves and lambs, but only recently has research looked at more long term effects on the performance of those offspring. Calves and lambs with low birth weight have slower pre-weaning growth rate and lower weaning weights than offspring with normal birth weight. This is a consequence of changes in muscle metabolism that result in slower rates of muscle growth and more nutrients being directed toward fat deposition, which ultimately impacts carcass quality even at the same body weight. Lambs with low birth weight have been shown to use feed energy less efficiently for muscle and fat deposition, and have altered reproductive performance such as lower blood progesterone concentrations during estrous and reduced formation of a corpus luteum, which could negatively impact fertility. Overall low birth weight resulting from severe nutrient restriction of the dam during gestation negatively affects several aspects of livestock production.
In normal beef cattle production systems, nutrient restriction of the dam severe enough to adversely affect birth weight of the offspring is uncommon. However, it has been reported that moderate nutrient restriction of the dam during gestation can also adversely affect performance of offspring. In the Great Plains and Western US, beef cows in late gestation may graze winter dormant native prairie that is low in protein, which does not negatively impact birth weight of calves. Until recently it was thought that beef cows could adapt to the lower plane of nutrition due to lower nutrient requirements during this time of the production cycle. However, recent studies at the University of Nebraska and University of Wyoming have changed that theory. Protein supplementation of dams grazing dormant native prairie increases weaning weight of offspring even though birth weight was not affected. Additionally, heifer offspring from protein-supplemented dams had greater pregnancy rates than those from non-supplemented dams, but there was no difference in pregnancy rates when rebred as first-calf cows. In the feedlot, fewer steers from protein supplemented dams were treated for respiratory and gastrointestinal disease, but rate of gain or feed efficiency were not affected. Protein supplementation of dams increased carcass weight, back fat, marbling score, and tenderness of rib eye muscle of steers compared with steers from non-supplemented dams. These reports demonstrate that even moderate nutrient restriction of pregnant cows can negatively impact performance of their offspring.
Also, over feeding pregnant dams does not enhance the performance of offspring more than offspring from dams fed to meet nutrient requirements. In fact, over feeding of pregnant dams may have negative effects on performance of offspring. Feeding pregnant ewes at 140% of nutrient requirements resulted in lower birth weight of lambs compared with lambs from dams fed at 100% of nutrient requirements. Ewe offspring from overfed dams had lower milk production during first lactation than those from dams fed 100% of nutrient requirements; the milk production of ewes from overfed dams was the same as ewes from nutrient restricted dams. Lambs from overfed dams had similar growth rate as lambs from dams fed at 100% of nutrient requirements, but both had faster growth rates than lambs from nutrient restricted dams. Overall, research results indicate that overfeeding dams during gestation does not increase performance of offspring compared with offspring from dams fed to meet nutrient requirements, and in some situations may have negative effects.
Currently, research is ongoing at the Range Cattle REC to evaluate the effect of maternal immune stimulation during late gestation on fetal programming of the immune response in subsequent offspring. Research in other species indicates that an immune challenge of the dam during gestation enhances the immune response in the offspring. The expected outcomes of this research are management practices that can be used to enhance immune competence of calves later in life and reduce costs associated with diseases such as bovine respiratory disease. Additionally, the use of winter native range for late gestation beef cows in Florida could provide a scenario similar to the situation in the Western US with late gestation cows grazing dormant native prairie. There may be a need for better nutritional management of cows grazing winter native range in Florida to offset potential negative effects on fetal development and offspring performance.
To date, research indicates that improper maternal nutrition can negatively impact performance of offspring, although results are somewhat inconsistent. Nutrient restriction of the dam does not appear to program the offspring in a positive manner in any way; all reported effects of maternal nutrient restriction negatively impact performance of the offspring. Similarly, overfeeding of the dam can cause poor performance of offspring, in addition to being costly. Unfortunately, sufficient research does not currently exist to make recommendations for nutritional management of the beef cow regarding the concept of fetal programming. Therefore, the best recommendation at the present time is to manage the nutrition of the cow herd to meet nutrient requirements (http://edis.ifas.ufl.edu/an190) throughout the beef cow production cycle.
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