Department - Author 1

Dairy Science Department

Degree Name - Author 1

BS in Dairy Science



Primary Advisor

Stan Henderson


The objective of the study was to determine activity using an activity monitoring system, Heatime. Data was collected from cows at the Cal Poly dairy from December 30, 2011 to January 6, 2012 whose results are from the previous program. This program involved prostaglandin in the form of Lutalyse given on Friday and cows were time bred the following Monday, 72 hours after the prostaglandin injection. Data collected from January 13, 2012 to current shows the new trial program which involved an injection of 5cc Lutalyse Monday and Tuesday, a vet check on Wednesday, time bred on Thursday, and a possible injection of Gonadotrophin- releasing Hormone (GnRH). Cows that have been checked by the veterinarian and are not showing signs of ovulation are given the additional GnRH injection. The results of both were compared to see if the additional injection caused immediate estrus cycling and showed signs of peak activity on the Heatime system more consistently than the previous program. Results showed that while not all cows came into estrus before or on the day of insemination, there were some consistencies in peak detection. The data showed that methods in which the two injections of Lutalyse were given on consecutive days, followed by time breeding on the fourth day had more instances where estrus was not demonstrated as peaking within the expected period. Although the results from those cows also given an injection of GnRH were shown to have higher instances of cows demonstrating peak estrus activity, it did not demonstrate enough to show that it is the best method. Limited results show that the new 4 day program without the incorporation of GnRH are not effective in creating peak activity and that the previous method of a single injection of Lutalyse may be the most beneficial. Factors that are possibilities for this outcome include time as a constraint, as well as inconsistent weather conditions over the duration of the new protocol. To see if results will change, data needs to be observed using more cows and a longer period of time as well as including more cows from the previous protocol.

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