Efficacy of Ovsynch Protocol with Antiprolactin Treatment for Timed Artificial Insemination During Non‐breeding Seasons in Yaks (Poephagus grunniens L.)

Abstract

An attempt was undertaken to investigate the efficacy of Ovsynch protocol for timed artificial insemination (TAI) with or without Norprolac (antiprolactin) treatment during non-breeding season (winter months) in yaks (n = 25). During non-breeding season, plasma prolactin profile has been reported high due to cold and nutritional stress. The Norprolac dose of i.m. administration was standardized for prolactin suppression. Three different doses viz. 2.5, 5.0 and 7.5 mg were attempted and the dose of 7.5 mg Norprolac i.m. per animal was found to be suitable for suppression of prolactin levels up to 30 h. Ovsynch treatment with Norprolac induced more number of oestrous symptoms per animal (4.8 vs 2.1), higher LH peak concentration (24.01 vs 16.16 ng/ml), longer duration of LH surge (6.8 vs 5.2 h) and higher conception rate (70 vs 30%) in Ovsynch plus Norprolac treated animals compared with animals treated with Ovsynch alone. Therefore, this study clearly indicates the opportunity for practical application of the Ovsynch plus Norprolac protocol for TAI in yaks during non-breeding seasons.

Hypothalamic Prolactin Regulation of Luteinizing Hormone Secretion in the Female Rat

“…Although pretreatment with ⌬1-9-G129R-hPRL augmented the magnitude of the LH surge, it had no effect on its time of onset. Similar observations were reported in GnRH-primed, prostaglandin F2␣-treated lactating yaks, in which suppression of PRL secretion with quinagolide (another D 2 R agonist) augmented the magnitude of LH surges induced by GnRH administration but did not affect its onset (93). The onset of the preovulatory LH surge in nocturnal rodents is timed to coincide with the reduction in daylight by the circadian pacemaker within the suprachiasmatic nucleus (SCN) the hypothalamus (94).…”

Effects of replacing soybean meal with slow-release urea on milk production of Holstein dairy cows

“…Twelve days after the second injection, the ovsynch programme was performed by injecting gonadotropin-releasing hormone (GnRH) (Kara et al, 2011). All animals were inseminated 16 hours after the second GnRH injection (Sarkar et al, 2010). The day after the first GnRH injection and on the day of insemination, a pregnancy rate diagnosis was performed by ultrasonography (Aloka ® SSD-500, Aloka, Wallingford, CT, USA), and the follicle diameters of the cows were determined.…”