Thesis (M.S.)--University of Wisconsin--Madison, 1982. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 71-76).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1949. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 113-121).

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 83-91).

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 76-85).

No description available.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1956. / Typescript. Abstracted in Dissertation abstracts, v. 16 (1956) no. 11, p. 2197. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 149-171).

Milk fever (parturient paresis / hypocalcaemia) is a metabolic disorder that usually occurs near parturition and at the onset of lactation in high producing multiparous dairy cows. Milk fever can indirectly contribute to an increased incidence of several diseases in early lactation. This study was conducted to compare two different feeding strategies to prevent milk fever, namely (i) the established concept of feeding a diet with a negative DCAD and (ii) a feeding strategy combining a negative DCAD supplement with 25-hydroxyvitamin D3 (25-OH-D3). Thirty dairy cows were used in a randomized block design and were selected and blocked by parity (second parity and later), 305 day mature equivalent milk production in the previous lactation and expected calving date. Within each of the 15 blocks, the cows were allocated to two experimental groups named DCAD and DCAD + HyD. Fifteen animals in the DCAD + HyD group received a daily oral dosage of 3 mg of 25-OH-D3. Plasma samples were collected from day 21 prepartum to 10 days postpartum and were analysed for 25-OH-D3, 1,25-dihydroxyvitamin D3, total and ionized calcium, phosphorus and magnesium. Samples were collected on day 21, 14, 10 prepartum and every second day to calving, 4 and 6 h postpartum and every second day up to day 10 after calving. Urinary samples for determination of macro minerals (calcium and phosphorus) were collected via manual stimulation on day 21, 14, 8 and 4 prepartum and day 4 postpartum. These samples were used to ensure that mild metabolic acidosis was achieved in both treatment groups. The metabolic acidosis was demonstrated by decreased urinary pH. Milk samples were collected on day 1, 4 and 10 postpartum and used for macro mineral (calcium and phosphorus) determination. This study did not achieve all of the expected results observed in similar experiments. No treatment differences could be detected for plasma Ca2+ concentrations (P>0.05) and the mean plasma Ca2+ concentrations were [1.086a mmol/L ± 0.010 (DCAD treatment) and 1.083a mmol/L ± 0.010 (DCAD + HyD treatment)] respectively.   Furthermore 1,25-(OH)2D3 plasma concentrations did not indicate any treatment differences (P>0.05). These results could be due to the fact that the experimental animals were not sufficiently challenged and therefore the combination of a low DCAD diet and Rovimix HyD did not influence the calcium homeostatic mechanisms as expected. A clear correlation between plasma 25-OH-D3 concentration and treatment duration was however demonstrated (P<0.001), indicating effective absorption of orally supplemented 25-OH-D3. Several authors demonstrated that feeding massive doses of vitamin D2 (30 million units) for extended periods led to clinical evidence of vitamin D toxicity. When 10 million IU of vitamin D3 were however administered intramuscularly within 10 days of parturition, a reasonable measure of protection against toxicity could be provided. It can be concluded from this study that longer feeding periods (± 21 days) than the proposed 10 days prior to calving can safely be implemented when feeding 3 mg 25-OH-D3 per animal per day (=240 mg Rovimix HyD 1,25%). Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Animal and Wildlife Sciences / unrestricted

Until recently, occurrence of milk fever (MF) has been attributed to prepartum calcium intake. However, researchers in Iowa have concluded that high prepartum dietary potassium (K) is the major cause of MF. Potassium concentrations have been increasing on manure fertilized soils over the last 20 years. Grasses grown on these fields mirror the increase in available soil K. When high K forages are fed to dry cows, it has been associated with increased MF in some, but not all cases. Our objective was to identify factors that differed between low and high occurrence of disorders when high K forages were fed. For 1 yr, monthly interviews were conducted on 10 dairies in Western Oregon. Close-up rations, dystocia rating, crowding, and cow comfort data were collected. Cows were diagnosed healthy or having one or more of the following metabolic diseases: MF, retained fetal membranes (RFM), and left displacement of the abomasum (LDA). Feedstuffs were collected each month and analyzed for dry matter, crude protein (CP), acid detergent fiber (ADF), and macrominerals. Of the multiparous cows (n=3,587) included, incidences of MF, RFM and LDA were 3.6, 11.3, and 1.5%, respectively. Increasing MF occurrence was associated with uncomfortable conditions, dystocia, increasing prepartum dietary Na and ADF, and increasing Ca to P ratios; there was also a dietary K by Mg concentration interaction. Increased dietary concentrations of Mg can prevent MF if dietary K is <2.6%. In addition, dietary conditions of K >2.6% and Mg >0.4% increase the occurrence of MF. Inversely, high concentrations of K can prevent MF in a Mg deficient diet. Dietary factors associated with an increase in the occurrence of RFM are increased dietary concentrations of Ca, S, CP, use of anionic salts, and the K forage source. Factors associated with an increase in hypocalcemia in the postpartum cow are crowding, uncomfortable housing, and a dietary K by Mg concentration interaction. In conclusion, improved cow comfort, and the addition of Mg to high K forage diets could decrease the risk of the cow exhibiting MF, RFM, and hypocalcemia. / Graduation date: 1999