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OPTIMIZING REPRODUCTIVE MANAGEMENT AND PERFORMANCE OF DAIRY CATTLE THROUGH PROMOTION OF ESTROUS EXPRESSION AND AUTOMATED DETECTION OF ESTRUS

dc.contributor.authorLaplacette, Ana Laura
dc.contributor.chairGiordano, Julioen_US
dc.contributor.committeeMemberCheong, Soon Honen_US
dc.contributor.committeeMemberHuson, Heatheren_US
dc.date.accessioned2024-04-05T18:36:39Z
dc.date.available2024-04-05T18:36:39Z
dc.date.issued2023-08
dc.description215 pagesen_US
dc.description.abstractThe research presented in this thesis evaluated the effect of targeted reproductive management (TRM) strategies that used automated detection of estrus during the voluntary waiting period (VWP) and synchronization of ovulation on the reproductive performance of lactating dairy cows. In addition, this research explored the value of using estrus alerts recorded during the VWP and synchronization of ovulation for prediction of reproductive performance. A randomized control experiment was conducted at a commercial dairy farm to evaluate the effect of a TRM program aimed at optimizing first service management and performance on reproductive outcomes of lactating dairy cows. The association between estrous expression during the VWP and reproductive performance was also evaluated. Cows were grouped based on having or not having estrus alerts during the VWP. After the end of the VWP, cows with or without estrus alerts were provided 30 or 16 d, respectively for insemination at detected estrus (AIE) before enrollment in a synchronization of ovulation protocol for TAI. Despite fewer pregnancies per AI (P/AI) at first service, the TRM program resulted in a similar pregnancy rate and proportion of cows pregnant at mid-lactation compared with a program that submitted all cows to TAI after synchronization of ovulation and had an extended VWP. A main advantage of the TRM program was increasing the proportion of cows that received AIE which minimized and targeted the use of TAI to cows that benefited most from the intervention. In addition, results from this experiment provided additional evidence of a strong positive association between expression of estrus during the VWP and reproductive outcomes. Cows with estrus alerts during the VWP had greater likelihood of expressing estrus after the end of the VWP, had more P/AI at first service, and more cows were pregnant by mid-lactation. The second experiment presented in this thesis was the first study in which induction of ovulation and TAI were delayed during a Double-Ovsynch protocol in lactating dairy cows. The experiment conducted at two commercial dairy farms evaluated the effect of delaying induction of ovulation for 24 h during a Double-Ovsynch protocol on the proportion of cows that expressed estrus before AI, and first service P/AI and pregnancy loss. In addition, the effect of estrous expression before AI on first service reproductive outcomes was also evaluated. Although delaying induction of ovulation increased the proportion of cows that received AIE and the overall proportion of cows that expressed estrus before TAI, overall first service P/AI were not increased and pregnancy losses were not reduced compared with the traditional timing of induction of ovulation. Nevertheless, enabling cows to express estrus at the end of the Double-Ovsynch protocol allowed differentiating cows with high versus low fertility before AI. Thus, estrous expression before AI could be used as a predictor of reproductive performance to create subgroups of cows for TRM. In summary, this research demonstrated the value of novel TRM strategies based on expression and automated detection of estrus for lactating dairy cows. Moreover, this research provided evidence of the feasibility of using estrous expression during the VWP and synchronization of ovulation protocols as a predictor of reproductive performance. Subgroups of cows identified and managed based on estrous expression can be targeted with specific management strategies designed to maximize dairy herd reproductive management and performance.en_US
dc.identifier.doihttps://doi.org/10.7298/xj4c-0d24
dc.identifier.otherLaplacette_cornell_0058O_11879
dc.identifier.otherhttp://dissertations.umi.com/cornell:11879
dc.identifier.urihttps://hdl.handle.net/1813/114504
dc.language.isoen
dc.rightsAttribution-NonCommercial-NoDerivatives 4.0 International*
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0/*
dc.titleOPTIMIZING REPRODUCTIVE MANAGEMENT AND PERFORMANCE OF DAIRY CATTLE THROUGH PROMOTION OF ESTROUS EXPRESSION AND AUTOMATED DETECTION OF ESTRUSen_US
dc.typedissertation or thesisen_US
dcterms.licensehttps://hdl.handle.net/1813/59810.2
thesis.degree.disciplineAnimal Science
thesis.degree.grantorCornell University
thesis.degree.levelMaster of Science
thesis.degree.nameM.S., Animal Science

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