Two studies were conducted to determine the effects of zinc (Zn), copper (Cu) and/or selenium (Se) on the humoral immune response of weaned steers fed diets deficient in these minerals. Steers were bled weekly for eight weeks to measure plasma mineral levels. Humoral immune response was measured as antibody response to Keyhole limpet hemocyanin (KLH) over seven weeks of the trials. Steers were injected with 0.5 ml KLH vaccine on weeks 2 and 5 of the Zn study. Ten steers (5 per treatment) were randomly assigned to either a Zn supplemented (z), 3.25 ml injectable zinc-oxide suspension (100 mg/ml oil) or a control (c) treatment. Plasma Zn was maintained at higher (P<.05) levels in supplemented steers from week 3 through week 8. Humoral immune response was not different (P>.10) between treatments. In 1988, 20 steers were stratified by weaning weight and randomly assigned to one of four treatments: 1) Injectable Se 1 ml Mu-Se/ 90.9 kg body weight, 2) Injectable Molycu 2 ml, 3) control, or 4) Se + Cu. Plasma Cu was higher (P<.05) in treatments 2 and 4 from week 2 through 8. Steers were injected with 0.5 ml of KLH vaccine on weeks 2 and 6. Immune response was not different (P>.10) between Cu supplemented steers and other treatments. Plasma Se was higher (P<.05) in treatment 1 as compared to 2 and 3, but not different (P>.10) from 4. Immune response was highest (P<.05) in treatment 1 with others not different(P>.10). In 1990, a second trial was conducted with 48 steers stratified by weight and randomly assigned to one of the same four treatments. Plasma Cu was higher (P<.05) on week 3 for both groups receiving Cu. Plasma Se was higher (P<.05) on weeks 2 through 5 for both groups receiving Se. Humoral immune response was higher (P<.05) on weeks 7 and 8 for both groups receiving Se. Humoral immune response was uneffected by Zn status of weaned beef steers. Selenium had a positive effect and Cu had no effect on humoral immune response of weaned beef steers. Copper also tended (P=.07) to reduce the positive response from Se. / Graduation date: 1991

Thesis (MSc (Agric)(Production Physiology)) -- University of Pretoria, 2007. / Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 87-99). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 87-99). Also available on the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1963. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph.D.) - University of Queensland, 2006. / Includes bibliography.

Thesis (B.App.Sc. (Hons.)) - University of Queensland, / Includes bibliography.

Thesis (M.S.)--University of Kentucky, 2007. / Title from document title page (viewed on June 14, 2007). Document formatted into pages; contains: vii, 57 p. : ill. Includes abstract and vita. Includes bibliographical references (p. 48-56).

These studies were conducted to define calf body shape, to test for relationships between calf shape and sire expected progeny differences for birth weight (BWTEPD) and first-calf calving ease (CEEPD) and to evaluate the efficacy of calf shape as a selection criterion for reduction of calving difficulty. Birth weight (BW), head circumference (HC), hip width (HW), shoulder width, body length (BL), cannon circumference (CC), cannon length (CL) and heart girth (HG) were measured at birth on 1,016 calves sired by Angus, Polled Hereford and Simmental bulls. In the Angus- and Polled Hereford-sired calves, sire effects were present for BW-adjusted residuals of CC. Additionally, HW, BL and HG residuals differed among half-sib groups for the Polled Hereford-sired calves. Thus, calf body measure differences independent of BW were in part attributable to sire. Multivariate factor analysis was used to identify underlying skeletal width and frame dimensions of calf shape in both breeds. After adjustment of body measures for differences in BW, a positive relationship of BWTEPD with HC and CC and a negative relationship between CEEPD and CC existed. Further adjustment for BWTEPD removed effects of CEEPD on CC. Thus, BWTEPD influenced calf shape independent of BW, but shape was not related to CEEPD independent of BWTEPD. Simmental bulls were divergently selected on CEEPD relative to BWTEPD so that body measures of calves from sires whose progeny tended to be born with more or with less dystocia than expected from BWTEPD could be obtained. Differences in CL and CC at constant BW were in part attributable to sire. Underlying shape factors were similar to those of the other breeds. Sire BWTEPD was positively related to CC and HC independent of BW. However, a relationship between body measures and CEEPD existed only at constant BW and BWTEPD. Calf shape independent of BW was also not different among calves born unassisted and assisted. Estimates of heritability, repeatability and birth to weaning relationships for each BW-residual body measure were generally not significant. Overall, sire BWTEPD was related to calf shape independent of BW. However, increases in skeletal dimensions were not related to either observed calving difficulty nor sire CEEPD independent of BW. Selection for reduced calving difficulty should not be based on calf body shape. / Ph. D.

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