Suboptimal reproductive performance leads to extended days open, increased culling due to reproductive failure, and decreased milk yield. Many factors influence the reproductive and productive performance of dairy herds, consequently, profitability. Choosing the most effective reproductive protocol for a given herd is a critical managerial decision. Two aspects were assessed: 1) The economic outcome of reproductive programs using estrous detection (ED), Ovsynch, or a combination of both, and 2) the impact of improving 10 percentage points (from 85% to 95%) in both compliance and the accuracy of ED on the timing to reach the new level of pregnancy and milk yield.
The following reproductive programs were evaluated: 1) ED: ED only; 2) Pre-Ov: Presynch-Ovsynch for first AI, and Ovsynch for resynchronization of open cows at 32 days after AI; 3) Pre-Ov-ED: same as Pre-Ov for first AI, but cows undergo ED and AI after first AI, and cows not reinseminated by 32 days after AI or diagnosed open 32 days after AI are resynchronized using Ovsynch. Cows were not AI after 365 days in milk (DIM) and open cows were culled after 450 DIM. Culled cows were immediately replaced with a nulliparous heifer 280 days pregnant. Herd was maintained at 1000 cows (lactating + dry). Death losses were set at 6% and abortion at 11.3%. Dry period of 60 days. Net daily value was calculated by subtracting the costs with replacement heifers ($1,800/heifer), feeding costs ($0.25/kg of lactating cow diet; $0.25/kg of dry cow diet), breeding costs ($0.1/cow/day for ED; $2.5/dose Prostaglandin F2alpha; (PGF); $3.0/dose gonadotrophin releasing hormone (GnRH); $0.17/injection administration), and other costs ($3.5/d) from the daily income with milk sales ($0.31/kg milk), cow sales ($0.75/kg live weight), and calf sales ($200/calf). Simulation was performed until steady-state was reached (3000 days), then average daily values for the subsequent 2000 days was used to calculate profit/cow/yr. First AI conception rate (CR) was set to 30% (decreased by 2.5% for every subsequent AI), and ED was set to 60%. Accuracy of ED (95 or 85%), and compliance with each injection (95 or 85%) were evaluated. Inaccurate ED resulted in 0% CR. Missing a Presynch injection resulted in loss of 50% of the benefit (40% increase to first AI), and missing an Ovsynch injection resulted in decrease in CR by 70%.
At 95% accuracy of ED and 95% compliance, the profits for ED, Pre-Ov, and Pre-Ov-ED were $403, $371, and $443, respectively. At 85% accuracy of ED and 85% compliance, the profits were $337, $277, and $378, respectively. The difference from 95% to 85% compliance and/or accuracy for ED, Pre-Ov, and Pre-Ov-ED was $56, $94, and $65, respectively. Combination of timed-AI with ED, with good compliance (95%) and accuracy (95%), will give you the best results. The ED is better than Pre-Ov with similar accuracy and compliance, but Pre-Ov with good compliance is better than ED with poor accuracy. Of all programs, Pre-Ov was the most sensitive to changes in compliance and/or accuracy of ED.
At 95% compliance and 95% accuracy of ED, the time length to reach the new level of pregnancy for ED, Pre-Ov, and Pre-Ov-ED was 3.4 months, 6.7 months, and 4.1 months, respectively. The time length to reach the new level of milk yield for ED, Pre-Ov, and Pre-Ov-ED took an additional 5.4 months, 8.8 months, and 7.5 months from pregnancy, respectively. According to the model, the new level of pregnancy should be evident around 3 to 6 months post-change with an additional 5 to 8 months for milk yield.
Assuming that the herd size remains constant, the timing to event (new level of pregnancy and milk yield) provides a timeline to monitor the expected true benefits when an improvement in reproductive management is made (compliance or accuracy of ED) at the farm level. Combination of Presynch-Ovsynch with ED resulted in the greatest profit, followed by ED and Presynch-Ovsynch only. The economic benefit of timed-AI protocols, such as Presynch-Ovsynch, depends on compliance with each injection. Dairy farmers should consider their accuracy of ED and compliance to reproductive protocols before implementing a reproductive program.
The information provided in this article was generated using an individual cow-based model to aid in decision making about reproductive management of dairy cows. The model was developed in collaboration with Drs. P. Federico (Capital University, Columbus, OH), A. De Vries (Department of Animal Sciences, University of Florida, Gainesville, FL), G.M. Schuenemann (Department of Veterinary Preventive Medicine, The Ohio State University, Columbus, OH), and K.N. Galvão (Department of Large Animal Clinical Sciences, University of Florida, Gainesville, FL).
- P. Federico, A. De Vries, G.M. Schuenemann, and K.N. Galvão. 2011. An individual cow-based model to aid in decision making about reproductive management of dairy cows. J. Dairy Sci. 94:350.
- G.M. Schuenemann, P. Federico, A. De Vries, and K.N. Galvão. 2011. Timing to reach the new level of pregnancy and milk yield after an improvement in reproductive management in dairy herds. J. Dairy Sci. 94:257.
- K.N. Galvao, P. Federico, A. De Vries, and G.M. Schuenemann. 2011. Economic comparison of reproductive programs for dairy herds using estrus detection (ED), Ovsynch, or a combination of both. J. Dairy Sci. 94:257.