Interactions of change in nutrition before and after artificial insemination on plasma and uterine histotroph mineral concentrations in beef heifers

Objective

These studies evaluated embryo recovery and nutritional changes before and after artificial insemination (AI) on circulating and uterine histotroph mineral concentrations.

Materials and Methods

In study 1, heifers (n = 79) were assigned to 1 of 2 treatments before and after AI: (1) low, 90% and 81% of maintenance energy requirements, or (2) high, 162% and 148% of maintenance energy requirements. At AI (d 0) half of the heifers were reassigned to the other treatment. Uteri were flushed on d 7 or 8. In study 2, heifers (n = 50) were only treated after AI (77.5% or 161.5% of maintenance energy requirements) until uteri were flushed on d 14.

Results and Discussion

In study 1, the low diet after AI resulted in reduced uterine S and Ca, indicating nutrient restriction after AI altered the uterine histotroph. When an embryo was recovered, uterine S, Ca, K, and Al were reduced, and Mg tended to be reduced. Thus, the embryo is likely using these minerals for growth and development. Plasma Mn, Mo, Zn, and Se were affected by time, indicating mineral bioavailability may vary during the estrous cycle. In study 2, heifers on the low diet tended to have elevated plasma Co and reduced uterine Fe. When an embryo was recovered, uterine Mg and S were reduced, and uterine Ca tended to be reduced and Mn tended to be elevated. Thus, Mg and S may be used by the developing embryo.

Implications and Applications

In summary, energy restrictions after AI reduced mineral concentrations in the uterine histotroph, potentially hindering embryo development as embryos appeared to use S, Ca, and Mg for development.