Influence of organic zinc on lactation performance and somatic cell count in dairy cows

Abstract

The objective of the study was to evaluate the effect of organically chelated zinc methionine (Zn-Met) supplementation on lactation performance of dairy cattle, i.e. milk yield (MY), milk components, and the somatic cell count (SCC) in early lactation. Eighty multiparous cows received two treatments (n = 40 per group) from 21 days prepartum throughout 14 weeks post partum (p.p.). Treatments consisted of 1) supplemental Zn-Met at the dose of 30 mg Zn/kg dry matter (DM) of the total mixed ration (TMR) for the supplemented (S) group; and 2) basal TMR without supplementation for the control (C) group. Daily MY of Zn supplemented cows 30 days p.p. was in not significantly affected (P > 0.05) by the treatment. After 60 days, the MY of the S-group was significantly higher (S: 44.70 ± 4.24 kg vs. C: 42.08 ± 4.60 kg, respectively); (P < 0.05). Ninety days p.p. there was a highly significant difference (P < 0.005) as well (S: 43.22 ± 4.47 kg vs. C: 39.98 ± 4.80 kg). Supplemented cows also produced significantly more milk fat and milk protein than the control on days 60 and 90 of the trial. There was a significant drop and a decreasing trend during the entire trial in SCC in S-group. Milk quality and udder health were positively affected by the Zn-Met treatment. This finding has an important implication for veterinary practice in an era of antibiotic reduction.