Genetic variability and trans-generational effects on production in dairy cattle

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A new phenomenon has been discovered in mammals over the last 2 decades, the influence of the mother's metabolic environment on the phenotype of the offspring. Although this has been initially observed in epidemiological survey in humans (Barker Hypothesis) it has been extended to all mammals studied so far including sheep and cows. The metabolic condition of both the mother and the father can leave functional trans-generational effects that will affect the health status and production of the following generation and in some conditions of the subsequent generation. The best example outside of the Dutch famine is the fat diet applied to mice which program obesity even on a normal diet. In bovines, it has been shown that feed restriction starting before conception has a direct influence on follicle count in the daughter. This is important since follicle count has a direct link with fertility in cows and in humans. Therefore, it can be postulated that the insemination of cows during a period of high lactation often associated with a negative energy balance may have programmed the daughter with a diminished ovarian reserve and lower fertility and lower production. Currently the magnitudes of such trans-generational effects in dairy cattle in Canada are not known are. It is proposed to use milk recording data on production and feed, together with health event data to estimate such trans-generational effects on production traits and hence determine whether these need to be accounted for in genetic evaluation systems and whether they could be incorporated into farm-management advising.