Effects of an injectable trace mineral supplement on first-service conception rate of dairy cows.

TitleEffects of an injectable trace mineral supplement on first-service conception rate of dairy cows.
Publication TypeJournal Article
Year of Publication2004
AuthorsVanegas JA, Reynolds J, Atwill ER
JournalJournal of dairy science
Volume87
Issue11
Pagination3665-71
Date Published2004 Nov
ISSN0022-0302
KeywordsAnimals, Cattle, Copper, Dose-Response Relationship, Drug, Female, Injections, Subcutaneous, Lactation, Logistic Models, Manganese, Multivariate Analysis, Pregnancy, Pregnancy Rate, Pregnancy, Animal, Random Allocation, Selenium, Trace Elements, Zinc
Abstract

A total of 825 dairy cows from a commercial dairy farm in central California were used to evaluate effects of one or 2 doses of an injectable trace mineral supplement containing 20 mg/mL of zinc, 20 mg/mL of manganese, 5 mg/mL of selenium, and 10 mg/mL of copper on first-service conception rate. Cows were randomly allocated into treatment or control group to either a single dose (experiment 1) or a double dose (experiment 2) of injected supplement. Allocation was based on days in lactation for experiment 1 and the length of gestation periods for experiment 2. In experiment 1, cows 38 to 45 d in lactation (n = 190) received a single dose of 5 mL of injected supplement. Similar cows were used as controls (n = 227). In experiment 2, cows and pregnant heifers received an initial injection of 5 mL of the mineral supplement from 2 to 3 wk precalving (n = 186). An equal dose was repeated 38 to 45 d in lactation. A similar group of cows and pregnant heifers served as controls for experiment 2 (n = 222). Health and reproductive events postcalving were recorded. In experiment 1, the odds of first-service conception were not significantly different for cows receiving a one-dose regimen of minerals compared with untreated control cows; conception rates were 26.8 and 27.5% for experiment 1 treatment and control groups, respectively. In experiment 1, the odds of first-service conception were significantly lower (odds ratio = 0.66) for cows and heifers given the 2-dose regimen of minerals compared with untreated controls; overall conception rates were 21.5 and 31.5% for experiment 2 treatment and control groups, respectively. In this intensively managed dairy herd, a single dose of injected trace minerals before breeding had no beneficial effects on first-service conception rate. However, dairy cows receiving a dose of trace minerals before calving and another dose before breeding had lower conception at first service.

DOI10.3168/jds.S0022-0302(04)73505-5
Alternate JournalJ. Dairy Sci.