- Animals: sheep
- Animal Production: feed additives, livestock breeding
Summary/AbstractReproductive efficiency is the most important factor contributing to a producer’s profitability. It has been suggested that the diet of the dam may impact the reproductive performance of their offspring. In cattle, cows fed a protein supplement during the last third of pregnancy had heifer calves that had an increase in pregnancy rates compared to heifer calves from cows that were not supplemented. In areas of North and South Dakota, there are soils which are rich in selenium. Selenium is a mineral which has been linked to decreasing certain types of cancer in humans. Furthermore, there is a real potential for ruminants grazing in the north central region of the US to experience prolonged periods of undernutrition during the first two thirds of gestation both in the absence and presence of selenium-rich forage. Because early gestation is a crucial period for fetal growth and differentiation, maternal high selenium and/or nutrient deprivation during this critical period may inhibit subsequent growth and thereby, alter ovarian development of the ewe lambs. We have shown that follicles in ovaries of female fetuses from ewes that are undernourished and fed high selenium levels had decreased numbers compared to control animals. It is the objective of this proposal to investigate if the decreased numbers of follicles observed in neonates, continue to be reduced immediately prior to puberty in ewe lambs born from ewes under the same treatments.
Project objectives from proposal:
The goal of this experiment is to determine if maternal consumption of differing levels of energy and/or selenium intake impacts ovarian development in female offspring near the time of puberty. Generating reproductive efficient offspring will greatly impact the economics behind sheep producers.
From this study, we will determine if the follicular retardation we see in term female fetuses continues at the time prior to breeding. This study will set the stage for a future study looking at how reproductive longevity and ewe replacement (and potentially heifer replacement) may be influenced by the maternal diet of the dam. Management of the breeding flock (or herd) may impact the numbers and the efficiency of the female replacements for either commercial or pure-bred breeders.
While we are aware that this proposal does not include a producer in this study, it is expected that producers will be asked to assist in the subsequent studies.
One of the greatest potential outcomes from this study is to impact the longevity of breeding females in a flock or herd. Much of the economic loss that occurs from a producer’s bottom line is culling young animals in the breeding herd. Monies and energy needed to develop the replacement female is lost if the female can not become pregnant in her first or second breeding seasons. Data from beef cattle suggests that the nutrition that the dam receives can impact the reproductive efficiency of her offspring. Indeed, a way to increase sustainability of our animal production systems is to have females which are retained in the herd for many breeding seasons. This study may help pinpoint that the nutrition supplied to a potential replacement female’s dam may be just as critical as ewe or heifer development itself.