An automated system for cattle reproductive management under the IoT framework. Part II: Induction of luteinizing hormone release after gonadotropin releasing hormone analogue delivery with e-Synch

Abstract

Technologies for automating animal management and monitoring tasks can improve efficiency and productivity of livestock production. We developed the e-Synch system for automated control and monitoring the estrous cycle of cattle through intravaginal hormone delivery and sensing. Thus, our objective was to evaluate luteinizing hormone (LH) concentrations after intravaginal instillation of the Gonadotropin-releasing hormone (GnRH) analogue Gonadorelin with the e-Synch system. This system consists of an intravaginal electronically controlled automated hormone delivery and sensing device integrated with an IoT platform. Lactating Holstein cows with their estrous cycle synchronized were used in two experiments (Exp). In Exp 1, at 48 h after induction of luteolysis, cows (n=5-6 per group) were randomized to receive 100 µg of Gonadorelin through intramuscular (i.m.) injection, 100 µg of Gonadorelin in a 2 mL solution delivered with e-Synch, and an empty e-Synch device. In Exp 2, at 48 h after induction of luteolysis cows (n=6-7 per group) were randomized to receive 100 µg of Gonadorelin i.m., or an intravaginal treatment with e-Synch consisting of 100 or 1,000 µg of Gonadorelin in 2 or 10 mL of solution containing 10% citric acid as absorption enhancer. Circulating concentrations of LH were analyzed with linear mixed models with or without repeated measurements. In Exp 1, cows in the i.m. Gonadorelin treatment had a surge of LH whereas cows in the other two treatments did not have a surge of LH for up to 8 h after treatment. In Exp 2, the 1,000 µg dose of Gonadorelin elicited more LH release than the 100 µg dose, regardless of solution quantity. The overall LH response as determined by area under the curve, mean, and maximum LH concentrations was similar between cows receiving 1,000 µg of Gonadorelin delivered with e-Synch and 100 μg of Gonadorelin i.m. Increasing volume of solution for delivering the same dose of Gonadorelin partially increased LH release only for the 100 µg dose. We conclude that the e-Synch system could be used to automatically release Gonadorelin in a dose and volume that induces a surge of LH of similar magnitude than after i.m. injection of 100 μg of Gonadorelin. Also, the dose of Gonadorelin delivered by e-Synch is more critical than the volume of solution used.

An automated system for cattle reproductive management under the IoT framework. Part I: the e-Synch system and cow responses

“…Conversely, all hormone reservoirs in all other devices in both experiments were completely empty suggesting that all fluid was released during insertion. Hormone solution release was also confirmed based on the physiological response observed in both experiments as described in the companion manuscript (Ren et al, 2023). This was more evident for cows that received a GnRH dose and volume of solution that caused an increase in circulating concentrations of LH above baseline.…”

“…Our in vivo experiments with dairy cows demonstrated that the current e-Synch system could be successfully programmed to deliver hormone solutions in a timely manner. Programmed hormone release was evidenced by the absence of fluid residue after device disassemble and the temporal dynamic of LH concentrations for cows that received GnRH in Exp 2 (Ren et al, 2023). Cows that received the high dose of GnRH had an LH surge of at least similar magnitude and timing than that of cows that received GnRH by i.m.…”

“…These experiments were also designed to evaluate cow behavioral and vaginal tissue responses to short-term exposure (i.e., < 1 d) to functional e-Synch devices. A detailed description of experimental procedures, hormone release, and effects of hormone release are presented in a companion manuscript (Ren et al, 2023).…”

“…Blood samples for determination of circulating concentrations of hormones were collected by puncture of caudal blood vessels using heparinized evacuated tubes (Vacutainer; BD, Franklin Lakes, NJ) as described in detail in the companion manuscript (Ren et al, 2023). In both experiments blood was collected at the same timepoints.…”

“…Our secondary objective was to characterize behavioral and physiological responses after e-Synch insertion because there is limited data about effects of device insertion and retention on cow behavioral responses and integrity of the vaginal mucosa. Implementation and evaluation of in vivo automated hormone delivery was also evaluated but is presented in a companion manuscript (Ren et al, 2023).…”