USE OF COW-SIDE PROGESTERONE TESTS TO IMPROVE REPRODUCTIVE-PERFORMANCE OF HIGH-PRODUCING DAIRY-COWS

This study evaluated the effectiveness of the cow-side ELISA milk prog esterone test in improving postpartum reproductive performance in the Dordt College dairy herd. Cows that produced more than 18,500 Ib of mi lk per lactation were assigned to the high production group (40 cows), while cows that produced less than 18,500 lb of milk (42 cows) were a ssigned to the low production group. Twenty-one cows in the high produ ction group and 19 cows in the low production group received no ELISA testing (untreated centrals), while the remaining cows in each group w ere evaluated by ELISA test every 7 d beginning on Day 27 post partum (treated cows). A sequence of 2 high progesterone tests and 1 low test indicated the cows were cycling normally. Cows that had tow milk prog esterone levels (< 5 ng/ml) for 3 consecutive tests were assumed to ha ve follicular cysts and were treated with 2 ml GnRH (Cystorelin, 50 mu g/ml). Cows that had 3 consecutive high tests (> 5 ng/ml) were assume d to have persistent corpora lutea (CL) and were treated with 5 ml PGF (2) alpha (Lutalyse, 5 mg/ml). In both the high and low production gro ups, treated cows had higher (P < 0.08) pregnancy rates by Day 210 tha n the untreated controls (63.2 vs 38.1% and 56.5 vs 42.1%, respectivel y). The days open were reduced (P < 0.05) for the treated animals by 4 1.6 d compared with the controls. The treated cows produced a net savi ngs of $70.42 (US) per cow assuming a $3.00 savings/day open.