Effects of an injectable trace mineral supplement on first-service conception rate of dairy cows.
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.
Veterinary Medicine Teaching and Research Center, University of California-Davis, Tulare 93274, USA. pajvanegas@ucdavis.edu <pajvanegas@ucdavis.edu>
J A
JA
Vanegas
J
J
Reynolds
E R
ER
Atwill
D000818:Animals; D002417:Cattle / Q000502:physiology*; D003300:Copper / Q000009:adverse effects / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D007279:Injections, Subcutaneous / Q000662:veterinary; D007774:Lactation / Q000187:drug effects / Q000502:physiology; D016015:Logistic Models; D008345:Manganese / Q000009:adverse effects / Q000494:pharmacology; D015999:Multivariate Analysis; D011247:Pregnancy; D018873:Pregnancy Rate; D011270:Pregnancy, Animal / Q000187:drug effects* / Q000502:physiology; D011897:Random Allocation; D012643:Selenium / Q000009:adverse effects / Q000494:pharmacology; D014131:Trace Elements / Q000009:adverse effects / Q000494:pharmacology*; D015032:Zinc / Q000009:adverse effects / Q000494:pharmacology
D014131:Trace Elements; D008345:Manganese; D003300:Copper; D012643:Selenium; D015032:Zinc