Interferon tau (IFN-τ) is the pregnancy recognition signal secreted by the trophectodermal cells of the developing bovine embryo that prevents luteolysis and maintains critical progesterone production. Recent evidence has suggested in addition to the mechanism of action identified in the uterus, there may be a direct effect of IFN-τ on...
Cystic ovarian disease (COD) is an anovulatory condition in cattle
that afflicts between 6-18% of all dairy cows in the US. Ovulation is
dependent on the plasminogen activator (PA) family of proteases
and protease inhibitor for proteolysis, culminating in follicular rupture.
Failure of the follicle to ovulate suggests an aberration...
Two experiments were conducted to examine the effect of
a cyclopropenoid fatty acid on luteal cell function. In Exp.
1, 12 mature ewes were mated to a fertile ram, assigned to two
groups (n = 6/group) and laparotomized on day 18 of gestation.
Ewes with corpora lutea (CL) in both...
Although the occurrence of ketosis is a postpartum phenomenon, recent studies have
focused on the prepartum period as key in the development of the disorder. Indicators of
prepartum energy status, such as depressed dry matter intake (DMI) and elevated plasma
non-esterified fatty acid (NEFA) concentrations have been associated with the...
Yeast culture supplementation has been used to improve the health and performance of dairy cows for the last 25 years. To evaluate the effect of a Saccharomyces cerevisiae fermentation product (Diamond V Original XP™) on the health and production of peripartal Holstein cows, two research studies were conducted.
The first...
Two experiments were conducted to evaluate the effects of
gonadotropin releasing hormone (GnRH) on the function of the bovine
corpus luteum during the estrous cycle. In Experiment 1, 10 heifers
were assigned randomly into two groups with each heifer serving as
her own control. Heifers in Group I (n=5) were...
The transition period is a time of increased nutritional demands and risk to metabolic and infectious diseases in dairy cows due to a suppressed immune system. These problems lead to reproductive challenges, increased culling rates, and decreased milk production postpartum, which leads to decreased profits. Feeding yeast (Saccharomyces cerevisiae) or...
Experiments were conducted to examine the effects of a tumor-promoting phorbol ester, a calcium ionophore and indomethacin on bovine luteal oxytocin (OT) synthesis and secretion and progesterone secretion. Six 18-month-old crossbred beef heifers in Exp. 1 and five similar heifers in Exp. 2 were observed twice daily for estrus using...