Browsing by Subject "seasonal"
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Item National Beef Quality Audit - 2011: Survey of Instrument Grading Assessments of Beef Carcass Characteristics(2012-11-16) Gray, Gatlan 1989-The instrument grading assessments for the NBQA-2011 evaluated seasonal trends of beef carcass quality and yield attributes over the course of the year. One week of instrument grading data?HCW, gender, USDA QG, and YG factors?were collected every other month (n = 2,427,074 carcasses) over a 13-month period (November 2010 through November 2011) from four beef processing corporations, encompassing 17 federally inspected beef processing facilities, to create an overview of carcass quality and yield attributes and trends from carcasses representing approximately 8.5% of the U.S. fed steer and heifer population. Mean yield traits were: YG (2.86), HCW (371.3 kg), FT (1.19 cm.), and LM area (88.39 cm^2). The YG distribution was YG 1 (15.7%), YG 2 (41.0%), YG 3 (33.8%), YG 4 (8.5%), and YG 5 (0.9%). Distribution of HCW was <272.2 kg (1.6%), 272.2 kg to 453.6 kg (95.1%), ?453.6 kg (3.3%). Monthly HCW means were: November 2010 (381.3 kg), January 2011 (375.9 kg), March 2011 (366.2 kg), May 2011 (357.9 kg), July 2011 (372.54 kg), September 2011 (376.1 kg), and November 2011 (373.5 kg). The mean FT for each month was November 2010 (1.30 cm), January 2011 (1.22 cm), March 2011 (1.17 cm), May 2011 (1.12 cm), July 2011 (1.19 cm), September 2011 (1.22 cm), and November 2011 (1.22 cm). The mean marbling score was Small49. USDA QG distribution was Prime (2.7%), Top Choice (22.9%), Commodity Choice (38.6%), and Select (31.5%). Interestingly, from November to May, seasonal decreases (P < 0.001) in HCW and FT were accompanied by increases (P < 0.001) in marbling. These data present the opportunity to further investigate the entire array of factors that determine the value of beef. Datasets utilizing the online collection of electronic data will likely be more commonly used when evaluating the U.S. fed steer and heifer population in future studies. These data indicate the wide array of carcasses produced by the beef cattle industry, and how the frequency of both YG and QG traits change from month-to-month.Item Reproductive neuroendocrine function in the mare as reflected in the intercavernous sinus during ovulatory, anovulatory, and transitional seasons(Texas A&M University, 2006-08-16) Cooper, Dee AWe hypothesized that marked reductions in secretion of luteinizing hormone (LH) during transitional and anovulatory periods can be accounted for by similar reductions in hypothalamic gonadotropin-releasing hormone (GnRH) secretion. Catheters were inserted surgically into the intercavernous sinus (ICS) of seven non-pregnant mares via the superficial facial vein during the ovulatory season (August 12-23), fall transition (November 15-30), the anovulatory season (January 19 - February 1) and spring transition (March 24 - May 12). Catheter placement was confirmed and standardized in each mare by lateral radiography. Ovarian status was monitored throughout the study by transrectal ultrasonography and serum concentrations of progesterone. During the breeding season, ICS blood samples were collected at 5-min intervals for 8 h when the dominant follicle reached approximately 35 mm and estrous behavior was observed. All mares ovulated within 5 d after sampling, except one mare who ovulated < 24 h before sampling. During the fall, mares were anovulatory (n = 5) or had a final ovulation within 5 d following intensive sampling (n = 2). Winter anovulation sampling was performed when all mares were anovulatory. During spring transition, each mare was sampled just before the second ovulation of the season. Similar to the ovulatory season, mares were sampled when the dominant, preovulatory follicle reached approximately 35 mm and estrous behavior was observed. Mean concentrations of LH were markedly higher (P < 0.01) during the breeding season than during all other seasons. Lower mean concentrations of LH in the fall transition, winter anovulation and spring transition sampling periods occurred coincident with a similar reduction (P < 0.01) in amplitude of LH pulses. Unexpectedly, neither the frequency (pulse/8 h) of LH pulses, frequency and amplitude of GnRH pulses, nor mean concentrations of GnRH differed among seasons. In addition, there were no differences observed due to season in mean concentrations of FSH or amplitude of FSH pulses. However, a small but significant (P < 0.05) reduction in the frequency of FSH pulses was observed during fall transition compared to all other seasons. In summary, contrary to accepted dogma, these results indicate that the photoperiodic initiation of seasonal anovulation in the mare is mediated at the level of the anterior pituitary, and appears to occur through a dampening of gonadotroph responsiveness to an unchanging pattern and magnitude of GnRH secretion.Item Seasonal variation in thyroxine in the American alligator (Alligator mississippiensis)(Texas A&M University, 2004-09-30) Crawford, Jared LouisMale and female alligators ranging from 58 cm to 361 cm in length (N=1054) were captured and their blood was sampled between 9 A.M. and midnight from June 2000 - June 2002 at the Rockefeller Wildlife Refuge in Grand Chenier, LA. Animals were captured in a variety of habitats including marsh, open water, canals, and ponds. Total thyroid hormones were measured by radioimmunoassay. Four criteria were used to evaluate changes in hormone levels: sex, total length, season, and time of day. Thyroxine (T4) varied over a wide range from 0.5 to 57 ng/mL. Triiodothyronine (T3) levels were below the sensitivity of the assay (<0.6ng/mL). A distinct seasonal peak in T4 was observed between December and April, peaking in March with highest mean T4 levels observed in the spring. Mean T4 declined significantly from the spring to an intermediate summer mean and declined significantly again in the winter. No T4 differences between the sexes were observed. Mean T4 was highest in juveniles, significantly lower in subadults, and significantly lower still in adults. Highest levels were found between 5 P. M. and midnight. With values up to 57 ng/ml in the spring, alligators exhibit T4 levels among the highest recorded for reptiles.