In a well-managed beef herd, heifers should represent the most valuable genetics in the herd and be an improvement on the previous generation of females. Recent economic conditions have brought forth a trend in which heifers are developed in “low input” management scenarios where they typically achieve 50-55% of projected mature body weight at breeding as opposed to the more traditional 65-70%. Seasonal differences in calf performance and heifer reproductive efficiency have also been observed. The uterine environment during gestation is known to have lifelong epigenetic effects on offspring. This is often achieved by imposing suboptimal conditions or nutrition prior to breeding or during gestation, and the effects may be translated to the developing calf by altered patterns of uteroplacental blood flow. Thus, it was hypothesized that low input heifer development protocols resulting in light weight heifers at breeding may cause decreased uteroplacental blood flow during pregnancy compared to traditionally developed females even when nutrition during gestation is equivalent. Furthermore, it was posited that calving season may also alter uteroplacental hemodynamics. Therefore, the objective of the present study was to evaluate the effects of heifer development practices and season on uteroplacental hemodynamics during mid to late gestation of nulliparous beef females.
Feet and leg soundness are of critical importance for breeding bulls, and lameness is a common problem affecting bulls. Lameness pain in the bovine typically has both inflammatory and neuropathic components, and often coincides with a decline in fertility. As neuropathic pain is refractory to non-steroidal anti-inflammatory drugs (NSAIDs), y-aminobutyric acid (GABA) analogues are commonly used in conjunction with NSAIDs to treat lameness in cattle. Meloxicam, an NSAID, and gabapentin, a GABA analogue, are frequently used extra-label under the supervision of a veterinarian to mitigate pain associated with lameness. Though neither of these compounds is currently labeled for use in bovines in the United States, previous research has indicated that the pharmokinetic profiles of these drugs support further evaluation for clinical use as analgesics in bovines. A decline in fertility is often observed in lame bulls; however, the pathogenesis of this transient subfertility is unknown. Currently, no controlled studies have been conducted to evaluate the effects of meloxicam and gabapentin analgesics on bull fertility. Thus, the objective of the present study was to evaluate the effects of meloxicam and gabapentin combination therapy on beef bull semen quality. It was hypothesized that treatment with meloxicam and gabapentin might have deleterious effects on semen quality.
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