{"id":{"repo_id":"colostate","oai_identifier":"oai:mountainscholar.org:10217/167051"},"canonical_url":"https://search.dev.ndltd.org/etd/colostate/oai:mountainscholar.org:10217/167051","repository":{"repo_id":"colostate","name":"Colorado State University","base_url":"https://api.mountainscholar.org/server/oai/request"},"display":{"title":"Effect of delaying time of AI based on Estrotect patch status on pregnancy rates of beef heifers and nursing beef cows","abstract":"Four studies were conducted to evaluate the efficacy of a delayed timed AI (TAI) protocol. The objective was to evaluate the use of Estrotect patch status to determine optimum TAI implementation. Experiment 1 was conducted with, 997 cows across 6 locations were administered a 7-d CO-Synch + controlled internal drug release (CIDR) estrous synchronization protocol. The experimental design was a 2 x 2 factorial; factors were patch status at 58 h post PGF2α injection (activated or inactivated) and time interval from PGF2α to TAI (58 or 76 h). Patch status was characterized at 58 h post PGF2α into 4 scores: 1 = 0% activated, 2 = 50% activated, 3 = 100% activated, and 4 = missing. Females with a patch status of 3 were considered to be activated and females with patch status of a 1 or 2 were considered to be not activated. Females with missing patches were removed. There was no treatment x location interaction for pregnancy rate (P = 0.96), so data were pooled across locations. There was a tendency (P = 0.07) for an interaction between the main effects for pregnancy rate. Pregnancy rate was greater (P < 0.01) in cows with activated patches at 58 h post PGF2α (67.0%) compared to those with inactivated patches (51.1%). There was no difference (P = 0.99) for pregnancy rate when comparing the 58 (59.9%) vs. 76 h PGF2α to TAI interval (58.7%). Pregnancy rates for cows with a patch status of 3 at 58 h post PGF2α were greater (P < 0.05) than cows with a patch status of 1 or 4 and tended (P = 0.09) to be greater than cows with a patch status of 2. Cows with a patch status of 1 tended (P = 0.06) to have increased pregnancy rates by delaying TAI to 76 h post PGF2α. Although, it was not different (P = 0.13), there was a 7.4 percentage point increase in pregnancy rates for cows with inactivated patches that received TAI at 76 vs. 58 h. Experiment 2 was conducted to evaluate delayed TAI on 1,682 heifers across 3 locations. The objective was to evaluate the use of Estrotect patch status at various recommended and delayed insemination times for a TAI protocol. Experiment 2a was implemented with 1,159 Bos taurus heifers synchronized using a 14 d melengestrol acetate (MGA) – PGF2α protocol. Estrotect patches were applied at the time of PGF2α injection and evaluated at the time of insemination. Heifers were subsequently assigned to 5 treatments: 1) recommended 72 h post PGF2α TAI with activated patches, 2) recommended 72 h post PGF2α TAI with inactivated patches, 3) 12 h delayed TAI with inactivated patches, 4)18 h delayed TAI with inactivated patches, and 5) heifers with missing patches. Experiment 2b was conducted with 449 Bos taurus heifers synchronized using a 14 d MGA – PGF2α protocol. Heifers were divided into 3 treatments: 1) recommended 72 h post PGF2α TAI with activated patches, 2) recommended 72 h post PGF2α TAI with inactivated patches, and 3) an 8 h delayed TAI with inactivated patches. Experiment 2c utilized 74 heifers synchronized with a 7-d CO-Synch plus CIDR protocol. All heifers had Estrotect patches applied at the time of CIDR removal and PGF2α injection. Patch status was evaluated 58 h post PGF2α injection on all heifers. This experiment was analyzed as a 2 x 2 factorial with patch status 58 h post PGF2α injection (activated or inactivated) and at the time of insemination (58 or 76 h). In experiment 2a, differences (P < 0.05) in pregnancy rates were different by patch status across treatments. Similarly, experiment 2b demonstrated resulted in differences (P < 0.05) in pregnancy rates when comparing the activated patch treatment to both the inactivated patch treatment and the delayed inactivated treatment. However, no differences (P > 0.05) were seen in either experiment 2a or 2b when comparing the recommended inactivated patch treatments to any of the delayed inactivated patch treatments regardless of delay interval. Experiment 2c demonstrated a tendency (P = 0.07) for the interaction pregnancy rates to be increased when activated patches at 58 h were inseminated at 58 h post PGF2α injection and when inactivated patches at 58 h were inseminated at 76 h post PGF2α. Pregnancy rates for the main effects of patch status (P > 0.05) and interval inseminated (P > 0.05) did not differ. Results show a definitive increase in pregnancy rates when comparing heifers with activated patches to heifers with inactivated patches. However, delaying insemination time of heifers with inactivated patches did not increase pregnancy rates.","abstract_html":"Four studies were conducted to evaluate the efficacy of a delayed timed AI (TAI) protocol. The objective was to evaluate the use of Estrotect patch status to determine optimum TAI implementation. Experiment 1 was conducted with, 997 cows across 6 locations were administered a 7-d CO-Synch + controlled internal drug release (CIDR) estrous synchronization protocol. The experimental design was a 2 x 2 factorial; factors were patch status at 58 h post PGF2α injection (activated or inactivated) and time interval from PGF2α to TAI (58 or 76 h). Patch status was characterized at 58 h post PGF2α into 4 scores: 1 = 0% activated, 2 = 50% activated, 3 = 100% activated, and 4 = missing. Females with a patch status of 3 were considered to be activated and females with patch status of a 1 or 2 were considered to be not activated. Females with missing patches were removed. There was no treatment x location interaction for pregnancy rate (P = 0.96), so data were pooled across locations. There was a tendency (P = 0.07) for an interaction between the main effects for pregnancy rate. Pregnancy rate was greater (P &lt; 0.01) in cows with activated patches at 58 h post PGF2α (67.0%) compared to those with inactivated patches (51.1%). There was no difference (P = 0.99) for pregnancy rate when comparing the 58 (59.9%) vs. 76 h PGF2α to TAI interval (58.7%). Pregnancy rates for cows with a patch status of 3 at 58 h post PGF2α were greater (P &lt; 0.05) than cows with a patch status of 1 or 4 and tended (P = 0.09) to be greater than cows with a patch status of 2. Cows with a patch status of 1 tended (P = 0.06) to have increased pregnancy rates by delaying TAI to 76 h post PGF2α. Although, it was not different (P = 0.13), there was a 7.4 percentage point increase in pregnancy rates for cows with inactivated patches that received TAI at 76 vs. 58 h. Experiment 2 was conducted to evaluate delayed TAI on 1,682 heifers across 3 locations. The objective was to evaluate the use of Estrotect patch status at various recommended and delayed insemination times for a TAI protocol. Experiment 2a was implemented with 1,159 Bos taurus heifers synchronized using a 14 d melengestrol acetate (MGA) – PGF2α protocol. Estrotect patches were applied at the time of PGF2α injection and evaluated at the time of insemination. Heifers were subsequently assigned to 5 treatments: 1) recommended 72 h post PGF2α TAI with activated patches, 2) recommended 72 h post PGF2α TAI with inactivated patches, 3) 12 h delayed TAI with inactivated patches, 4)18 h delayed TAI with inactivated patches, and 5) heifers with missing patches. Experiment 2b was conducted with 449 Bos taurus heifers synchronized using a 14 d MGA – PGF2α protocol. Heifers were divided into 3 treatments: 1) recommended 72 h post PGF2α TAI with activated patches, 2) recommended 72 h post PGF2α TAI with inactivated patches, and 3) an 8 h delayed TAI with inactivated patches. Experiment 2c utilized 74 heifers synchronized with a 7-d CO-Synch plus CIDR protocol. All heifers had Estrotect patches applied at the time of CIDR removal and PGF2α injection. Patch status was evaluated 58 h post PGF2α injection on all heifers. This experiment was analyzed as a 2 x 2 factorial with patch status 58 h post PGF2α injection (activated or inactivated) and at the time of insemination (58 or 76 h). In experiment 2a, differences (P &lt; 0.05) in pregnancy rates were different by patch status across treatments. Similarly, experiment 2b demonstrated resulted in differences (P &lt; 0.05) in pregnancy rates when comparing the activated patch treatment to both the inactivated patch treatment and the delayed inactivated treatment. However, no differences (P &gt; 0.05) were seen in either experiment 2a or 2b when comparing the recommended inactivated patch treatments to any of the delayed inactivated patch treatments regardless of delay interval. Experiment 2c demonstrated a tendency (P = 0.07) for the interaction pregnancy rates to be increased when activated patches at 58 h were inseminated at 58 h post PGF2α injection and when inactivated patches at 58 h were inseminated at 76 h post PGF2α. Pregnancy rates for the main effects of patch status (P &gt; 0.05) and interval inseminated (P &gt; 0.05) did not differ. Results show a definitive increase in pregnancy rates when comparing heifers with activated patches to heifers with inactivated patches. However, delaying insemination time of heifers with inactivated patches did not increase pregnancy rates.","abstract_has_math":false,"creators":["Markwood, Matthew, author","Peel, Kraig, advisor","Ahola, Jason, advisor","Whittier, Jack, committee member","Hadrich, Joleen, committee member"],"institution":"Colorado State University. Libraries","degree_name":"Master of Science (M.S.)","degree_level":"Masters","degree_discipline":"Animal Sciences","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015","date_published":"2015","updated_at":"2026-07-27T19:12:54Z","subjects":["delayed insemination","timed artificial insemination","estrus detection aid","beef cattle"],"languages":["eng","English"],"rights":["Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright."],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://doi.org/10.25675/3.018297"],"render_values":[{"text":"https://doi.org/10.25675/3.018297","href":"https://doi.org/10.25675/3.018297","code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10217/167051","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Markwood, Matthew, author","Peel, Kraig, advisor","Ahola, Jason, advisor","Whittier, Jack, committee member","Hadrich, Joleen, committee member"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2015-08-28T14:34:53Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2015-08-28T14:34:53Z"]},{"key":"dc:date.issued","label":"Date","values":["2015"]},{"key":"dc:publisher","label":"Institution","values":["Colorado State University. 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The experimental design was a 2 x 2 factorial; factors were patch status at 58 h post PGF2α injection (activated or inactivated) and time interval from PGF2α to TAI (58 or 76 h). Patch status was characterized at 58 h post PGF2α into 4 scores: 1 = 0% activated, 2 = 50% activated, 3 = 100% activated, and 4 = missing. Females with a patch status of 3 were considered to be activated and females with patch status of a 1 or 2 were considered to be not activated. Females with missing patches were removed. There was no treatment x location interaction for pregnancy rate (P = 0.96), so data were pooled across locations. There was a tendency (P = 0.07) for an interaction between the main effects for pregnancy rate. Pregnancy rate was greater (P < 0.01) in cows with activated patches at 58 h post PGF2α (67.0%) compared to those with inactivated patches (51.1%). There was no difference (P = 0.99) for pregnancy rate when comparing the 58 (59.9%) vs. 76 h PGF2α to TAI interval (58.7%). Pregnancy rates for cows with a patch status of 3 at 58 h post PGF2α were greater (P < 0.05) than cows with a patch status of 1 or 4 and tended (P = 0.09) to be greater than cows with a patch status of 2. Cows with a patch status of 1 tended (P = 0.06) to have increased pregnancy rates by delaying TAI to 76 h post PGF2α. Although, it was not different (P = 0.13), there was a 7.4 percentage point increase in pregnancy rates for cows with inactivated patches that received TAI at 76 vs. 58 h. Experiment 2 was conducted to evaluate delayed TAI on 1,682 heifers across 3 locations. The objective was to evaluate the use of Estrotect patch status at various recommended and delayed insemination times for a TAI protocol. Experiment 2a was implemented with 1,159 Bos taurus heifers synchronized using a 14 d melengestrol acetate (MGA) – PGF2α protocol. Estrotect patches were applied at the time of PGF2α injection and evaluated at the time of insemination. Heifers were subsequently assigned to 5 treatments: 1) recommended 72 h post PGF2α TAI with activated patches, 2) recommended 72 h post PGF2α TAI with inactivated patches, 3) 12 h delayed TAI with inactivated patches, 4)18 h delayed TAI with inactivated patches, and 5) heifers with missing patches. Experiment 2b was conducted with 449 Bos taurus heifers synchronized using a 14 d MGA – PGF2α protocol. Heifers were divided into 3 treatments: 1) recommended 72 h post PGF2α TAI with activated patches, 2) recommended 72 h post PGF2α TAI with inactivated patches, and 3) an 8 h delayed TAI with inactivated patches. Experiment 2c utilized 74 heifers synchronized with a 7-d CO-Synch plus CIDR protocol. All heifers had Estrotect patches applied at the time of CIDR removal and PGF2α injection. Patch status was evaluated 58 h post PGF2α injection on all heifers. This experiment was analyzed as a 2 x 2 factorial with patch status 58 h post PGF2α injection (activated or inactivated) and at the time of insemination (58 or 76 h). In experiment 2a, differences (P < 0.05) in pregnancy rates were different by patch status across treatments. Similarly, experiment 2b demonstrated resulted in differences (P < 0.05) in pregnancy rates when comparing the activated patch treatment to both the inactivated patch treatment and the delayed inactivated treatment. However, no differences (P > 0.05) were seen in either experiment 2a or 2b when comparing the recommended inactivated patch treatments to any of the delayed inactivated patch treatments regardless of delay interval. Experiment 2c demonstrated a tendency (P = 0.07) for the interaction pregnancy rates to be increased when activated patches at 58 h were inseminated at 58 h post PGF2α injection and when inactivated patches at 58 h were inseminated at 76 h post PGF2α. Pregnancy rates for the main effects of patch status (P > 0.05) and interval inseminated (P > 0.05) did not differ. Results show a definitive increase in pregnancy rates when comparing heifers with activated patches to heifers with inactivated patches. However, delaying insemination time of heifers with inactivated patches did not increase pregnancy rates."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["born digital","masters theses"]},{"key":"dc:title","label":"Title","values":["Effect of delaying time of AI based on Estrotect patch status on pregnancy rates of beef heifers and nursing beef cows"]}]}],"canonical_facts":{"dc:creator":["Markwood, Matthew, author","Peel, Kraig, advisor","Ahola, Jason, advisor","Whittier, Jack, committee member","Hadrich, Joleen, committee member"],"dc:date.accessioned":["2015-08-28T14:34:53Z"],"dc:date.available":["2015-08-28T14:34:53Z"],"dc:date.issued":["2015"],"dc:description.abstract":["Four studies were conducted to evaluate the efficacy of a delayed timed AI (TAI) protocol. The objective was to evaluate the use of Estrotect patch status to determine optimum TAI implementation. Experiment 1 was conducted with, 997 cows across 6 locations were administered a 7-d CO-Synch + controlled internal drug release (CIDR) estrous synchronization protocol. The experimental design was a 2 x 2 factorial; factors were patch status at 58 h post PGF2α injection (activated or inactivated) and time interval from PGF2α to TAI (58 or 76 h). Patch status was characterized at 58 h post PGF2α into 4 scores: 1 = 0% activated, 2 = 50% activated, 3 = 100% activated, and 4 = missing. Females with a patch status of 3 were considered to be activated and females with patch status of a 1 or 2 were considered to be not activated. Females with missing patches were removed. There was no treatment x location interaction for pregnancy rate (P = 0.96), so data were pooled across locations. There was a tendency (P = 0.07) for an interaction between the main effects for pregnancy rate. Pregnancy rate was greater (P < 0.01) in cows with activated patches at 58 h post PGF2α (67.0%) compared to those with inactivated patches (51.1%). There was no difference (P = 0.99) for pregnancy rate when comparing the 58 (59.9%) vs. 76 h PGF2α to TAI interval (58.7%). Pregnancy rates for cows with a patch status of 3 at 58 h post PGF2α were greater (P < 0.05) than cows with a patch status of 1 or 4 and tended (P = 0.09) to be greater than cows with a patch status of 2. Cows with a patch status of 1 tended (P = 0.06) to have increased pregnancy rates by delaying TAI to 76 h post PGF2α. Although, it was not different (P = 0.13), there was a 7.4 percentage point increase in pregnancy rates for cows with inactivated patches that received TAI at 76 vs. 58 h. Experiment 2 was conducted to evaluate delayed TAI on 1,682 heifers across 3 locations. The objective was to evaluate the use of Estrotect patch status at various recommended and delayed insemination times for a TAI protocol. Experiment 2a was implemented with 1,159 Bos taurus heifers synchronized using a 14 d melengestrol acetate (MGA) – PGF2α protocol. Estrotect patches were applied at the time of PGF2α injection and evaluated at the time of insemination. Heifers were subsequently assigned to 5 treatments: 1) recommended 72 h post PGF2α TAI with activated patches, 2) recommended 72 h post PGF2α TAI with inactivated patches, 3) 12 h delayed TAI with inactivated patches, 4)18 h delayed TAI with inactivated patches, and 5) heifers with missing patches. Experiment 2b was conducted with 449 Bos taurus heifers synchronized using a 14 d MGA – PGF2α protocol. Heifers were divided into 3 treatments: 1) recommended 72 h post PGF2α TAI with activated patches, 2) recommended 72 h post PGF2α TAI with inactivated patches, and 3) an 8 h delayed TAI with inactivated patches. Experiment 2c utilized 74 heifers synchronized with a 7-d CO-Synch plus CIDR protocol. All heifers had Estrotect patches applied at the time of CIDR removal and PGF2α injection. Patch status was evaluated 58 h post PGF2α injection on all heifers. This experiment was analyzed as a 2 x 2 factorial with patch status 58 h post PGF2α injection (activated or inactivated) and at the time of insemination (58 or 76 h). In experiment 2a, differences (P < 0.05) in pregnancy rates were different by patch status across treatments. Similarly, experiment 2b demonstrated resulted in differences (P < 0.05) in pregnancy rates when comparing the activated patch treatment to both the inactivated patch treatment and the delayed inactivated treatment. However, no differences (P > 0.05) were seen in either experiment 2a or 2b when comparing the recommended inactivated patch treatments to any of the delayed inactivated patch treatments regardless of delay interval. Experiment 2c demonstrated a tendency (P = 0.07) for the interaction pregnancy rates to be increased when activated patches at 58 h were inseminated at 58 h post PGF2α injection and when inactivated patches at 58 h were inseminated at 76 h post PGF2α. Pregnancy rates for the main effects of patch status (P > 0.05) and interval inseminated (P > 0.05) did not differ. Results show a definitive increase in pregnancy rates when comparing heifers with activated patches to heifers with inactivated patches. However, delaying insemination time of heifers with inactivated patches did not increase pregnancy rates."],"dc:format.medium":["born digital","masters theses"],"dc:identifier":["Markwood_colostate_0053N_12757.pdf"],"dc:identifier.uri":["http://hdl.handle.net/10217/167051","https://doi.org/10.25675/3.018297"],"dc:language":["English"],"dc:language.iso":["eng"],"dc:publisher":["Colorado State University. Libraries"],"dc:rights":["Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright."],"dc:subject":["delayed insemination","timed artificial insemination","estrus detection aid","beef cattle"],"dc:title":["Effect of delaying time of AI based on Estrotect patch status on pregnancy rates of beef heifers and nursing beef cows"],"dc:type":["Text"],"thesis:degree_discipline":["Animal Sciences"],"thesis:degree_level":["Masters"],"thesis:degree_name":["Master of Science (M.S.)"],"thesis:institution_name":["Colorado State University"]},"updated_at":"2026-07-27T19:12:54Z"}