Plasma and tissue zinc enrichment altered by different sources of zinc using stable isotopes in weaned male Holstein calves facing dietary antagonism.

Trace minerals are an important component of ruminant nutrition. Furthermore, understanding the bioavailability of various trace mineral sources is essential for accurate dietary formulation. The objective of this trial is to determine the effect of a Zn antagonism, elevated S, on the resulting plasma and tissue Zn enrichment, while also determining if differences occur depending on Zn source, Zn glycinate, and Zn methionine hydroxy analog chelate, in Holstein calves. Thirty weaned male Holstein calves were used in a randomized complete block design. Calves were fed a texturized starter varying in sodium sulfate concentration for 32 d. On d 30, calves were orally administered 0 (n = 6) or 8 (n = 24) mg of Zn from each of 2 sources: 67Zn-glycinate (Zn-Gly) and 70Zn-methionine hydroxy analog chelate (Zn-MHAC) as a pulse dose. Blood was collected via catheters before isotope administration and 0.25, 0.5, 0.75, 1, 2, 3, 4, 5, 6, 8, 10, 12, 24, 30, 36, and 48 h after isotope administration for determination of isotope enrichment. Calves were killed 48 h after isotope administration and target tissues harvested, weighed, and sampled for determination of isotope enrichment. Though DMI differed, calves receiving the high diet (11.3 ± 0.2 g od S/d) consumed 2.9 times more S than low diet (3.9 ± 0.2 g of S/d). Tissue isotope enrichment decreased with high S diet for the following tissues: rumen, reticulum, omasum, duodenum, jejunum, ileum, kidney, and lung. Tissue isotope enrichment was greater with Zn-MHAC compared with Zn-Gly for the following tissues: rumen, reticulum, omasum, abomasum, duodenum, jejunum, ileum, kidney, lung, heart, spleen, and thymus. A significant interaction of S concentration and Zn source was observed for rumen and omasum. The effect of high dietary S on tissue Zn isotope enrichment demonstrates efficacy of this antagonistic model in ruminants. Moreover, changes in Zn enrichment of the splanchnic tissues suggests a high metabolic rate for Zn. Finally, the improved enrichment from Zn-MHAC demonstrates greater tissue Zn incorporation regardless of antagonism presence when compared with Zn-Gly.