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:
- The economic outcome of reproductive programs using estrus detection, Ovsynch, or a combination of both.
- The impact of improving 10 percentage points (from 85 percent to 95 percent) 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:
- Estrus detection only.
- Presynch-Ovsynch: Presynch-Ovsynch for first AI, and Ovsynch for resynchronization of open cows at 32 days after AI.
- Presynch-Ovsynch-estrus detection: same as previous protocol for first AI, but cows undergo estrus detection and AI after first AI, and cows not re-inseminated by 32 days after AI or diagnosed open 32 days after AI are resynchronized using Ovsynch.
Cows did not receive AI after 365 days in milk (DIM) and open cows were culled after 450 DIM.
Culled cows were immediately replaced with a bred heifer that was 280-days pregnant. Herd was maintained at 1,000 cows (lactating and dry). Death losses were set at 6 percent and abortion at 11.3 percent. Dry period was 60 days.
Net daily value was calculated by subtracting the costs with replacement heifers ($1,800 per heifer), feeding costs ($0.25 per kilogram of lactating cow diet; $0.25/kilograms of dry cow diet), breeding costs ($0.1 per cow per day for estrus detection; $2.5 per dose Prostaglandin F2alpha; (PGF); $3 per dose gonadotrophin releasing hormone (GnRH); $0.17 per injection administration), and other costs ($3.5 per day) from the daily income with milk sales ($0.31 per kilogram of milk), cow sales ($0.75 per kilogram of live weight), and calf sales ($200 per calf). Simulation was performed until steady-state was reached (3,000 days), then average daily values for the subsequent 2,000 days was used to calculate profit per cow per year.
First AI conception rate (CR) was set to 30 percent (decreased by 2.5 percent for every subsequent AI), and ED was set to 60 percent. Accuracy of estrus detection (95 or 85 percent), and compliance with each injection (95 or 85 percent) were evaluated. Inaccurate estrus detection resulted in 0 percent CR. Missing a Presynch injection resulted in loss of 50 percent of the benefit (40 percent increase to first AI), and missing an Ovsynch injection resulted in a decrease in CR by 70 percent.
At 95 percent accuracy of estrus detection and 95 percent compliance, the profits for estrus detection, Presynch-Ovsynch, and Presynch-Ovsynch-estrus detection were $403, $371, and $443, respectively.
At 85 percent accuracy of estrus detection and 85 percent compliance, the profits were $337, $277, and $378, respectively.
The difference from 95 percent to 85 percent compliance and/or accuracy for the three protocols was $56, $94, and $65, respectively.
A combination of timed-AI with estrus detection, with good compliance (95 percent) and accuracy (95 percent), will give you the best results. The estrus detection protocol is better than Presynch-Ovsynch with similar accuracy and compliance, but Presynch-Ovsynch with good compliance is better than estrus detection with poor accuracy.
Of all programs, Presynch-Ovsynch was the most sensitive to changes in compliance and/or accuracy of estrus detection.
At 95 percent compliance and 95 percent accuracy of estrus detection, the time to reach the new level of pregnancy for the three protocols was 3.4 months, 6.7 months, and 4.1 months, respectively.
The time length to reach the new level of milk yield for the protocols 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 three to six months post-change with an additional five to eight months for milk yield.
Assuming that 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 estrus detection) at the farm level.
The combination of Presynch-Ovsynch with estrus detection resulted in the greatest profit, followed by estrus detection 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 estrus detection 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, Ohio), 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, Ohio), and K.N. Galvão (Department of Large Animal Clinical Sciences, University of Florida, Gainesville, Fla).
- 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.
Source: Buckeye Dairy News, July issue