Effects of increasing dietary zinc sulfate fed to primiparous ewes: I. Effects on serum metabolites, mineral transfer efficiency, and animal performance

Objective The objective of this research was to determine the effects of increasing Zn concentrations during late gestation on serum metabolites, serum mineral element transfer efficiency ratios (TE), and ewe and lamb performance in a semi-extensive management system. Materials and Methods Commercial white-face (WF; n = 23) and black-face (BF; n = 24) ewes (age ≈18 mo; BW 87.48 ± 8.37 kg) were sorted into breed-type groups and within groups ranked by BW and randomly divided into 3 dietary supplement treatment groups along the rank: CON (n = 13, 40 mg/kg Zn, ≈1 × NASEM recommendations), Zn500 (n = 19, 500 mg/kg Zn, ≈4 × NASEM recommendations), and Zn1000 (n = 15, 1,000 mg/kg Zn, ≈7 × NASEM recommendations). Treatments were administered in pelleted alfalfa (0.45 kg/ewe per day) fortified with Zn sulfate to increase Zn concentrations fed from 87.5 ± 8.9 d of gestation until parturition. Results and Discussion Maternal treatment did not affect ewe BW change throughout the experiment, nor serum metabolites, mineral element TE, or progeny performance through weaning (P ≥ 0.06). However, ewe greasy fleece weight the following year was greater for Zn500 than Zn1000 ewes (4.13 ± 0.18 kg vs. 3.48 ± 0.19 kg; P = 0.03) but did not differ between CON and the other treatments (3.68 ± 0.22 kg; P ≥ 0.22). The most marked effects were observed between breeds where Zn TE of WF ewes and lambs (264.3 ± 23.2) was approximately twice that of BF ewes and their lambs (165.4 ± 19.7; P Implications and Applications The results suggest feeding Zn supplemented from Zn sulfate beyond current NASEM recommendations from d 87 of gestation until parturition had minimal beneficial effects on fine-wool or meat-type ewes and lambs. Breed differences observed in serum mineral element concentrations (Fe and Zn) and related TE of the neonatal lamb may provide insights into adaptive trace mineral supplementation strategies based on breed type and related levels of production.