ABSTRACT
Bovine maternal behavior is known to be influenced by a variety of factors including hormonal mediation, breed, age, parity, host genetics and general management practices. Following centuries of varying levels of domestication processes, the behavior of the bovine cow has altered from that of her original wild ungulate ancestors, although many maternal instincts have remained unchanged. The influence of maternal behavior on calf health and performance is of interest to cow-calf beef production operations, as in most instances, the cow is solely responsible for rearing the calf until weaning. However, investigating the magnitude of this influence is challenging, in part because objective measurement of behavioral traits is difficult, particularly in extensive settings. In recent years, while a number of remote monitoring devices have been developed that afford opportunities for objective measurement of behavioral traits in livestock, characterization of physiological mechanisms that underlie superior maternal behavior, including identification of potential biomarkers remains elusive in cattle. Hormonal profiles during the periparturient period have been shown to influence behavioral patterns in both current and future generations in other mammalian species and may provide insights into the physiology of bovine maternal behavior. Therefore, the aim of this review is to describe general characteristics of bovine maternal behavior and the factors known to influence it, including hormonal drivers, through which cross-reference to other species is made. Current methods of measuring and assessing behavior that may also be applicable to most production settings have also been reviewed. At present, there is no known hormonal assay that can be used to measure and/or reliably predict bovine maternal behavior post-calving or across generations. Being able to objectively assess superior maternal behavior, whether that be through remote monitoring, hormonal profiling or indirectly through measuring calf performance will be beneficial to livestock industries in the future.
ABSTRACT
Managing the return to regular cyclicity after the winter anestrous period in the mare has been a challenge for the equine breeding industry. Specifically, efforts have been made to shift or shorten the vernal transition period and to have it followed by a predictable first ovulation at the commencement of the breeding season. Intravenous administration of kisspeptin is known to stimulate an LH response in both reproductively active and inactive mares. This study examined the effects of a constant rate infusion (CRI) of kisspeptin on mares during vernal transition. Mares were given a 30 hours infusion of kisspeptin at a low and high rate (66 nmol [88 µg] and 100 nmol [130 µg] per hour, respectively) or saline, and the LH and follicular response tracked. Plasma samples were collected every 15 minutes for the first 6 hours to determine if there is an acute effect of kisspeptin infusion on LH secretion. Plasma samples were then collected every 3 hours for a total of 72 hours to examine the ability of kisspeptin to stimulate an LH surge. A CRI of kisspeptin increased LH secretion in these mares but was not able to stimulate an LH surge. To examine the effect of kisspeptin on ovarian activity, follicular measurements were collected ultrasonographically until ovulation occurred or the follicles regressed. CRI of kisspeptin at these rates was unable to induce ovulation earlier than controls.
