Temporal variables of the Shackleford Banker horse intermediate gaits

Abstract

s / Journal of Equine Veterinary Science 33 (2013) 321-399 322 cell proliferationwas reduced in response to the inhibitor of cellular proliferation, porcine Transforming Growth Factorbeta. The ability to fuse and formmultinucleated myotubes is one of the critical capabilities of differentiated myogenic cells. Fusion percentage was calculated as the ratio of the number of myotube nuclei (a myotube is identified by the presence of three or more nuclei within a continuous cell membrane) to total nuclei. After 144 – 168 hours in culture, the ESC fused into large, stable, multinucleated myotubes with resultant cultures exhibiting 75-80% fusion. Further characterization included establishing that the doubling time of the equine satellite cells is 17.7 hours, consistent with other muscle cells grown in culture. We have sucessfully isolated equine satellite cells that maintain their myogenic phenotype in culture. We have optimized cell culture conditions and demonstrated that equine satellite cells respond in the expected manner to both positive and negative components present in the culture media. In other species satellite cells play a key role in postnatal muscle growth and repair of injuredmuscle.We are now inposition to utilize the ESC to investigate the role of satellite cells in these important processes in equine muscle. Temporal variables of the Shackleford Banker horse intermediate gaits M.C. Nicodemus , J. Beranger , and L. Ward 1 Mississippi State University, Mississippi State, MS, 39762, 2 American Livestock Breeds Conservancy, Pittsboro, NC, 27312 Shackleford Banker horse (SBH) is a Spanish Colonial horse (SCH) breed listed on the American Livestock Breeds Conservancy (ALBC) critically endangered list. In accordance to the Shackleford Banks Wild Horses Protection Act, SBH are currently managed by the National Park Service and the Foundation for Shackleford Horses, a nonprofit organization, with Shackleford Island numbers maintained under 150 horses. Selection of horses maintained on the Shackleford Island is based on the health of the animal and the characteristics that will preserve the heritage of the breed. Since other SCH are classified as gaited, SBH are assumed to perform similar gaits despite the lack of research done to confirm this assumption. To better manage the soundness of the herd and to improve horse selection, the objective of this study was to measure the temporal variables of the SBH intermediate gaits. Subject selection was a cooperative effort consisting of experts from the ALBC and the Foundation for Shackleford Horses with their selection based on soundness and best representation of the breed type. Eight SBH were filmed at a slow (SV: 2.43 0.22 m/s) and fast (FV: 3.25 0.14 m/s) intermediate gait. Gait velocity ranges were based on the ranges found in previous gaited horse studies. Frame-byframe analysis was performed on 10 symmetrical strides for each horse for each velocity. Stride variables were given as a % of stride duration with Student paired t-tests applied to determine differences between velocities (P<0.05). At the slower velocity, the footfall sequence was lateral alternating between lateral (12 3%) and diagonal bipedal support (DBS) (88 3%), while the faster velocity had a diagonal footfall sequence alternating between suspension (23 4%) and DBS (77 5%). While stride length (SV: 1.75 +0.20 m, FV: 1.95 0.13 m) remained consistent between the two velocities, stride duration (SV: 0.73 0.03 s, FV: 0.60 0.03 s), fore (SV: 50 5%, FV: 39 3%) and hind (SV: 50 6%, FV: 39 4%) stance durations, diagonal advanced placements (SV: 6 2%, FV: 0 1%), and DBS decreased at the faster velocity as stride rate (SV: 1.38 0.06 strides/s, FV: 1.67 0.09 strides/s) increased (P<0.05). Similar to other SCH, the SBH has the ability to perform a 4-beat stepping intermediate gait, but this ability is limited to the slower velocity and may be an example of a transitional gait as the horse transitions from the walk to the trot. Nevertheless, the velocity and the limb support sequencing of this transitional gait is unique from other gaited and non-gaited horse breeds. In addition, the mechanism used for increasing velocity, limb pairing and increased stride rate instead of increased stride length, is distinctive from other horse breeds studied that exhibited a 4-beat stepping intermediate gait, and thus, can be applied in the understanding of this