What Do You Know About Fetal Programming?

by North Dakota State University Area Extension Livestock Specialist Janna Kincheloe

 

The relationship between nutrition and reproduction has been well established with measures such as calving interval, calf health and survival, and overall pregnancy rates affected by body condition score at calving. To date, most research has focused on optimizing reproductive response in the dam through management and nutrition during gestation, with little focus on how these strategies may influence the developing offspring throughout their productive lives.

The concept that the gestational environment can have both short-term and permanent impacts on offspring is referred to as developmental or fetal programming. This theory was developed over 20 years ago based on human medical evidence, and subsequent research has confirmed that the developing fetus is responsive to maternal metabolic, hormonal, and nutritional signals during critical periods of development. There is increasing evidence that maternal undernutrition can result in changes in metabolic and physiological functions that can impact animal performance, carcass characteristics, and reproductive traits in adult offspring.

Development of reproductive tissues in beef cattle begins early in the first trimester. In a spring calving herd, nutrient deficiency early in gestation may occur due to low forage quality and/or quantity, as well as inadequate supplementation programs. Because the lifetime supply of viable eggs is established prior to birth, it is important to consider management practices that could impact reproductive capacity in beef cattle. However, most research is focused on nutrition during late gestation when the majority of fetal growth occurs. Information related to early maternal nutrition and reproductive development of female offspring is somewhat limited.

Several studies conducted in sheep have indicated a delay in fetal ovarian development due to maternal undernutrition; however, long-term effects on reproductive efficiency have not been thoroughly evaluated. Another study reported reduced ovulation rates in adult offspring of mothers who were underfed during the first trimester, but not during the second and third trimesters of pregnancy.

Antral follicle count (AFC) has shown some promise as an indicator of the size of the ovarian reserve in cattle, and has been used to evaluate the effect of nutrient restriction on reproductive potential. Results of these studies indicated that females whose dams were restricted to 60 percent of maintenance requirements during the first trimester of gestation have reduced AFC despite similar birth weights and growth rates compared to offspring from dams fed the control treatment. Another study reported smaller follicles and fewer AFC in adult heifers when dams received a low-protein diet in early gestation followed by a high-protein diet in the second trimester of pregnancy.

The impact of maternal nutrition on reproductive capacity of beef cattle is still a relatively unexplored topic due to high costs of long-term research trials and the requirement for large animal numbers in order to evaluate differences between management strategies. Although mechanisms for observed responses have not been fully evaluated, current research indicates that management decisions may influence a herd for generations to come. Adequate nutrition throughout gestation is of critical importance in ensuring optimal performance of both dams and offspring.