Effects of replacing sulfate with hydroxychloride sources of trace minerals on health and reproduction in dairy cows.

The objectives were to evaluate the effects of replacing sulfate (sulfate trace minerals [STM]) with hydroxychloride (hydroxychloride trace minerals [HTM]) sources of Cu, Mn, and Zn on health, reproduction, and survival in dairy cows. A total of 141 Holstein cows were stratified by parity group prepartum as nulliparous or parous cows and, within parity, nulliparous cows were blocked by genomic breeding value for ECM yield and parous cows by recently completed lactation 305-d ECM. Within block, cows were assigned to STM or HTM, and prepartum diets contained (mean ± SD) 15 ± 1, 58 ± 2, and 66 ± 3 mg/kg of diet DM as Cu, Mn, and Zn, respectively, whereas postpartum diets contained 19 ± 3, 65 ± 15, and 77 ± 11 mg/kg diet DM as Cu, Mn, and Zn, respectively. Treatments were fed from 246 d of gestation to 105 DIM. Concentrations of nonesterified fatty acids (NEFA), BHB, haptoglobin, and ceruloplasmin were measured in plasma, and those of total Ca (tCa) were measured in serum. Diseases were diagnosed in the first 105 d postpartum and survival was evaluated until 305 DIM. The estrous cycle of cows was synchronized and artificial insemination (AI) was performed on d 87 postpartum. On d 19 after AI, serum was analyzed for progesterone and blood mononuclear cells, and cervical cells were analyzed for mRNA for interferon-stimulated genes (ISG). Treatment did not affect the concentrations of NEFA, BHB, tCa, and progesterone in blood. Feeding HTM reduced the concentrations of haptoglobin in the first 19 d postpartum (40.0 ± 9.1 vs. 25.7 ± 5.0 µg/mL) and that of ceruloplasmin only on d 6 postpartum (0.64 ± 0.03 vs. 0.58 ± 0.03 mg/mL). Feeding HTM reduced the risk of retained placenta (11.5% ± 6.3% vs. 3.8% ± 2.3%) and tended to reduce the risks of clinical (16.4% ± 9.7% vs. 4.0% ± 2.9%) and subclinical endometritis (29.8% ± 9.2% vs. 16.4% ± 5.7%). Cows fed HTM tended to have a reduced rate (adjusted hazard ratio = 0.58; 95% CI = 0.33-1.04) and risk of morbidity (51.7% ± 9.1% vs. 32.7% ± 7.1%) during the first 105 d postpartum compared with feeding STM. Feeding HTM increased the relative expression of ISG by 1.7 to 2.0-fold in blood mononuclear cells on d 19 after AI in pregnant cows compared with STM; however, treatment did not affect the expression of ISG in cervical cells. Rate of pregnancy did not differ between treatments, but HTM tended to increase the proportion of pregnant cows by 305 d postpartum (68.8% ± 5.7% vs. 82.8% ± 4.7%) partially attributed to the reduced proportion of cows designated as do not inseminate (25.6% ± 5.3% vs. 9.8% ± 3.6%). In addition, HTM reduced the rate (adjusted hazard ratio = 0.44; 95% CI = 0.20-0.96) and risk of leaving the herd by 305 d postpartum from 26.5% ± 9.6% in STM to 11.9% ± 5.0%. Replacing sulfate sources of Cu, Mn, and Zn with hydroxychloride sources of the same trace minerals benefited health of cows in early postpartum, which carried out to benefit reproduction and survival.