Abstract
This study used a stochastic simulation model to estimate the potential economic benefit of using timed artificial insemination (TAI) in combination with conventional unsorted (TCONV) and sexed (TSEX) semen in heifers only (TCONV-H, TSEX-H) and in both heifers and lactating cows (TCONV-HC, TSEX-HC) in a high-producing, pasture-based production system. The scenarios were compared with a conventional reproductive policy (CONV) in which heifers and cows were inseminated with conventional unsorted semen after estrus detection. Sensitivity analysis was also used to estimate the effect of hormone costs from TAI use on the profitability of each program relative to CONV. The mean annual (± standard deviation) profit advantage (ΔPROF) over CONV for TCONV-H, TCONV-HC, TSEX-H, and TSEX-HC scenarios were €3.90/cow ± 4.65, €34.11/cow ± 25.69, €13.96/cow ± 6.83, and €41.52/cow ± 42.86, respectively. Combined application of both technologies was shown to return a greater annual ΔPROF on average compared with that achievable from TAI alone. However, the risk of not returning a positive annual ΔPROF varied across the scenarios with higher risk in TCONV-H and TSEX-HC. Specifically, TCONV-H and TSEX-HC had a 24 and 18% chance, respectively, of not returning a positive annual ΔPROF. Sensitivity analysis showed that when hormone costs increased by €10/cow TCONV-H and TSEX-HC had a 38 and 23% chance, respectively, of not returning a positive annual ΔPROF. The range in ΔPROF for TCONV policies was most sensitive to the TAI pregnancy rate and TSEX policies were most sensitive to the relative fertility achieved with sexed compared with unsorted semen. This study has shown TAI and sexed semen are complementary technologies that can increase genetic gain and profitability in a pasture-based, dairy production system.
Highlights
Reproductive performance is a fundamental driver of dairy herd profitability (Meadows et al, 2005; Galvão et al, 2013)
The greatest annual ∆PROF was achieved in TSEX-HC followed by Timed AI of conventional unsorted (TCONV)-HC, TSEX-H, and TCONV-H
The annual ∆PROF distributions per cow and per hectare were negative for TCONV-H, TCONV-HC, and TSEXHC
Summary
Reproductive performance is a fundamental driver of dairy herd profitability (Meadows et al, 2005; Galvão et al, 2013). In seasonal-calving pasture-based systems, the effect of poor reproductive performance is manifested in an increased spread in the annual calving profile, resulting in shorter lactations and suboptimal matching of pasture supply to peak feed demand. Long-term rates of genetic gain may be diminished in less fertile herds due to a lower selection intensity, as a greater proportion of heifer calves must be retained as herd replacements. Use of sexed semen (SS) can increase the selection intensity by decreasing the proportion of females required to produce a target number of dairy replacement heifers. Combined application of both technologies could return a higher profit advantage compared with that achievable from using either in isolation
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