Abstract
This study evaluated the effect of an injectable multi-mineral complex supplementation on grazing beef cows on subsequent offspring birth weight (BW) and adjusted weaning weight (AWW). Experiment 1 included 1,128 Angus crossbred multiparous suckled cows, from 9 locations in Virginia, that were randomly assigned to one of two treatments: 1) One dose of an injectable trace mineral (6 mL; Multimin® 90, Multimin USA, Ft. Collins, CO) at 71.4±16.8 d of lactation (n = 560); or 2) a negative control with no trace mineral injection (n = 568). In experiment 2, 986 Angus crossbred multiparous suckled cows, at 7 locations in Virginia, were randomly assigned to one of two treatments: 1) Two doses of an injectable trace mineral (6 mL; Multimin® 90) at 118.3±17 days before calving and at 67.7±17.4 d of lactation (n = 494); or 2) negative control with no trace mineral injection (n = 492). All cows had ad libitum access to forage and water, and received additional mineral supplementation in form of mineral blocks. Calves were weaned at approximately 7 months of age, and 205-day AWW was calculated based on birth day, age of weaning and age of dam. No differences between treatments were detected for BW (33.7±1.01 kg; P = 0.50) and AWW (212.2±5.0 kg; P = 0.25) when only one dose of injectable trace mineral was administered to the dam at early lactation. Similarly, when two doses of injectable trace mineral were administrated BW (35.6±1.1 kg; P = 0.70) and AWW (259.4±6.1 kg; P = 0.83) did not differ between treatments. In conclusion, one or two doses of injectable trace mineral administrated at late gestation and/or during lactation had no effect on offspring BW and AWW.
Mammary Gland Structures Are Not Affected by an Increased Growth Rate of Yearling Ewes Post-Weaning but Are Associated with Growth Rates of Singletons
