The current study involved two experiments that were conducted at the Texas A&M AgriLife Research and Extension Center in Uvalde, TX (semi-arid environment) from 2006 to 2008. In experiment one, Bonsmara bulls ( n = 39; 20-24 mo of age) were joined with multiparous Bonsmara and Bonsmara-influenced females (n = 1013) during a 90-day breeding season in 2006, 2007, and 2008 to quantify the effects of a reduction in bull to female ratio on reproductive performance. Bulls were also placed with primiparous beef females ( n = 142). Bulls were allotted by selected physical traits, social rank, serving capacity, and seminal traits to one of two bull to female (BFR) treatments: Low (1:30-1:45; n = 10 pastures) or Conventional (1:16-1:26; n = 12 pastures) BFR. Pregnancy rate (P = 0.36), calving date (P = 0.24), and calving rate (P = 0.25) did not differ between Conventional and Low BFR treatments. The current experiment demonstrates that Low BFR can be utilized in breeding pastures of up to 2,090 ha without negatively affecting reproductive performance. In experiment two, Bonsmara heifers (3/4, 7/8, and full bloods) were exposed to Bonsmara bulls from April 15 to July 15 during each of the two years. Heifers were weighed, rectally palpated for pregnancy, and scored for BCS (1 thin - 9 fat) and frame score (1 short - 9 tall) in December (end of second trimester) during years 1 and 2. Heifers were stratified on expected calving date and randomly allotted to one of two levels of nutrition for the remainder of gestation. In year 1, heifers were allotted to range forage (n=31, low nutrition, LN) or to non-irrigated oat pasture (n=31, high nutrition, HN). In year 2, heifers were placed onto the same range environment as in year 1 (n=31, LN) or onto irrigated ryegrass pasture (n=31,HN). Heifers in the LN groups were supplemented with 20% CP cubes at the rate of 0.9 kg/heifer/day from January 2 until calving while HN heifers were not supplemented. Within 4 hr of birth, calves were weighed, and calf vigor and calving difficulty scores were recorded. Heifers were weighed within 72 hours of parturition. From treatment initiation through calving, HN heifers gained 48.6 kg whereas the LN females lost 15 kg. Twice as many HN heifers required major assistance at calving as compared to LN heifers. Calves born to the HN females weighed 3.7 kg more at birth than those born to LN females. These differences resulted in HN heifers having (P = 0.005) more calving difficulty than LN heifers (mean calving difficutly of 2.3 for HN and 1.6 for LN). The calves of the HN females were also less vigorous (P = 0.005) after birth than the calves from LN females (calf vigor score of 2.2 for HN and 3.3 for LN). Consequently, the level of nutrition during the third trimester of gestation can affect calving difficulty, calf vigor, and female weight.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

The bull shark, Carcharhinus leucas, is an important euryhaline predator that is exploited throughout its range for meat and fins. This species is taxonomically paired with the pigeye shark, C. amboinensis. Validity of this group has not been directly tested using molecular markers. Genetic variation and phylogeny was examined with concatenated datasets of mitochondrial genes (cytb, cox1 and 12stRNA16s) for nineteen species, from three families within the order Carcharhiniformes. Whilst there were indications of species pairings within the genus, there was no evidence to suggest that the bull and pigeye sharks should be considered a species group. Phylogenetic analysis failed to resolve Carcharhinus, but confirmed Negaprion as a sister taxon and placed Prionace glauca within Carcharhinus. It remains unclear if the family Sphyrnidae, arose from a Rhizoprionodon or Scoliodon ancestor and future revision of this complex group of sharks is required. Like other large carcharhinid species, C. leucas exhibits a low reproductive rate and long generation times. It is susceptible to localised depletions and such declines have been documented. The global stock structure was assessed by analysing the mitochondrial control region in 245 individuals sampled from eight populations in three ocean basins. The bull shark exhibits relatively high haplotype diversity (0.896 ± 0.010) when compared to other globally-distributed sharks and the nucleotide diversity was similar to others from the genus (0.00465 ± 0.00014). There was significant stock structure found among populations (ΦST=0.736, p<0.00001) and among ocean basins (ΦCT=0.527, p=0.00653). Geneflow between the US Atlantic coastline and Gulf of Mexico was sufficient to consider the area to be a single panmictic population. Coalescent analyses suggest an Indian Ocean origin with population divergences associated with warm interglacials and increased habitat with drop in sea level during the recent Wisconsin glaciation. Seven discrete stock management units for bull sharks are proposed.

Resident bull trout (Salvelinus confluentus) may be particularly vulnerable to human related disturbance, however very few studies have focused on resident bull trout populations. The abundance of bull trout is one measure of the strength and potential for persistence of a population. Habitat characteristics may influence resident bull trout abundance to differing degrees and by varying means at multiple spatial scales. We used day and night snorkel counts to assess relative bull trout abundance. A modification of the Forest Service R1/R4 Fish and Fish Habitat Inventory was used to assess habitat characteristics associated with resident bull trout. Logistic and multiple linear regression were used to assess the relationships between resident bull trout abundance and habitat characteristics at the patch (1 to 5 km), reach (0.5 to 1 km) and habitat unit (1 to 100 m) scales. Site categorical variables were used along with quantitative habitat variables to explain among-site and across-site variation in the data. The significance of both quantitative habitat variables and categorical site variables at various spatial scales suggest that relationships between bull trout abundance and habitat characteristics are complex and in part dependent on scale. The characteristics of individual habitat units explained little of the variation in bull trout presence/absence (logistic regression; Somers' D=0.44) and density (multiple linear regression; adjusted R��=0.08) in habitat units, however there were habitat characteristics that were significantly (P���0.05) correlated to bull trout presence/absence and density in habitat units. The relationships between habitat characteristics and bull trout presence/absence and density varied between habitat unit types. There was a strong quadratic relationship between bull trout abundance and mean summer water temperature at the reach (P=0.004) and patch scales (P=0.001). The mean temperature of patches appears to explain some of the variation in bull trout density at smaller spatial scales, such as reaches and habitat units. An appreciation of the complex nature of scale dependent interactions between bull trout abundance and habitat characteristics may help resource managers make wiser decisions regarding conservation of resident bull trout populations. / Graduation date: 2000

Video and industry data were used to assess the inter-relationships of aggression, delivery, coat color, year of birth, number of outs, buckoff percent and score in rodeo bulls. An evaluation of laterality based on observations of how the individual animals were loaded into chutes at 11 bull riding events showed 63% left-handed delivery and 37% right-handed delivery across all observations (n = 525). There was a similar distribution for aggressiveness (based on whether or not the bull charged after the rider dismounted) with 64% of bulls being non-aggressive and 36% of bulls being aggressive. Significant linear relationships existed between score and number of outs and score and buckoff percentage indicating that experience impacted performance. The correlation between number of outs and buckoff percentage was low to moderate (0.06 to 0.30), depending upon the subset of data evaluated. The r-square value for the analysis of score among all bulls was 0.14; however, the r-square value in the subset of bulls with known sires with more than one son was 0.68 when sire was included in the model. Similar increases in r-square values were observed for 2006 average score, career average score, buckoff percentage, and career buckoff percentage, indicating important genetic influences on these traits and/or their component traits. Investigations into the relationship between performance and aggression may help bucking stock producers improve the selection criteria they use. The current trend within the industry is for several breeders to breed ‘hot’ or flighty, nervous cattle to achieve higher performing offspring. Given that there was no association between aggression and score based on chi-square test, aggression may be removed from the criteria for using certain animals for breeding purposes. Based on results from this work, if bucking stock breeders want to make genetic changes in these traits, documentation of pedigree information is vital.

The current study involved two experiments which were conducted at the Texas A&M Agricultural Research and Extension Center in Uvalde (semi-arid environment) from 2002 to 2004. In experiment one, Bonsmara bulls (n = 19; 20-24 mo of age) were joined with multiparous, crossbred females (n =586) for 90 d in 2003 and 2004. Bulls were allotted by selected physical traits, seminal traits, social rank, and serving capacity to one of two bull to female ratio (BFR) treatments: Conventional (1:21-1:29; n = 6 pastures) or Low (1:47-1:52; n = 2 pastures) BFR. Pregnancy rate (P = 0.33), calving rate (P = 0.26), and calving date (P = 0.22) did not differ between Conventional and Low BFR treatments. Post-breeding evaluation of bulls in 2002 (n = 16) indicated that social rank, but not seminal traits, was significantly correlated with pre-breeding values (P < 0.05). The current study demonstrates that Low BFR can be utilized in single- and multisire, 90-d breeding pastures of up to 2,090 ha without adversely affecting reproductive performance. In experiment two, yearling, one-half or three-quarter Bonsmara heifers (n = 106; 11-14 mo of age) were palpated per rectum and assigned a reproductive tract score (RTS) immediately prior to the beginning of the breeding season. Reproductive performance was measured in their two subsequent breeding years in order to estimate the value of the RTS system in extensively-managed, natural mating, 90-d breeding season programs. RTS was positively correlated (p < 0.01) with frame score (r = 0.25), age (r = 0.31), weaning weight (r = 0.47), and the weight of the heifer on the day of RTS exam (r = 0.56). The RTS means by dam parity also differed (P < 0.03). A lower (P < 0.01) percentage of females conceived during each of their first two breeding seasons for heifers of RTS 1 and 2 (65.2%) than for heifers of RTS 3, 4, and 5 (91.2%). Females with a RTS of 1 had a lower pregnancy rate over each of their first two breeding seasons, conceived later during their first breeding season, weaned lighter first calves, and remained lighter each year for fall body weight and body condition score than did heifers with RTS of 2 to 5 (P < 0.05). Collectively, the results of the current study indicate that heifers with a RTS of 1 immediately prior to a 90-d breeding season should be culled. Consideration should also be given to eliminating RTS 2 heifers, but further studies will be needed to confirm the potential economic advantage of this practice.

A study was conducted to evaluate effects of housing and feeding systems on performance of neo-natal Holstein bull calves. Treatments included individually housed, bottle-fed (n = 5 calves), individually housed, bucket-fed (n = 5 calves), group housed bottle fed (n = 5 pens) and group housed bucket fed (n = 5 pens). Body weights were collected every 7 days and serum and plasma samples were taken on day 0, 28, 55 and 66 for beta-Hydroxybutyrate concentrations. No major differences (P > 0.11) in performance (average daily gain, dry matter intake, and feed efficiency) or β-Hydroxybutyrate (P > 0.14) concentrations were observed between housing and feeding treatments. Likewise, no differences (P > 0.26) were observed in the coefficient of variation for BW or fecal scores or morbidity. Albeit performance wasn’t altered, group housing provides a social environment and bucket feeding lowers the variation of intake amongst the group.

Thesis (Ph. D.)--Oregon State University, 1990. / Typescript (photocopy). Includes bibliographical references. Also available via the World Wide Web.

Thesis (PhD)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: Christopher S. Guy. Includes bibliographical references (leaves 135-150).

Thesis (Ph. D.)--Oregon State University, 1997. / Typescript (photocopy). Includes bibliographical references (leaves 219-230). Also available online.