Effects of Zinc Methionine Complex on Milk Production and Somatic Cell Count of Dairy Cows: Twelve-Trial Summary

Abstract

The objective of this review was to summarize 12 trials (13 comparisons) evaluating effects of zinc methionine (ZM) complex (ZINPRO®; Zinpro Corporation, Eden Prairie, MN) on lactation performance and udder health. Summarized trials were conducted in Washington (2), Colorado (2), New York, Illinois, Arkansas, Missouri, Georgia, Great Britain, Germany, and Israel. In 5 of the trials, ZM provided between 180 and 200 mg of zinc/d per head; in the remaining 7 trials (8 comparisons), ZM supplied 360 to 400 mg of zinc. In all diets, cows received additional zinc from inorganic sources, with the exception of the control diet in one of the Missouri comparisons. For statistical evaluation, each trial was considered as a block, and the treatment least squares mean within a trial was treated as an observation using a mixed model. Cows fed ZM produced more (P<0.01) milk (31.8 vs 30.5 kg/d), energy-corrected milk (31.7 vs 30.4 kg/d), and fat-corrected milk (31.6 vs 30.0 kg/ d) than control cows. Milk composition did not differ (P>0.15) between treatment and control cows. Somatic cell count (SCC; 1000/mL) was reduced from 294 to 196 (P<0.01) in cows receiving ZM. This summary of 12 dairy trials indicates that ZM increases lactation performance and improves udder health, as a 33.3% reduction in SCC occurred.