In the past 20 years, boron has been identified as an essential trace element for animals and humans but also as an increasingly important industrial pollutant. We examined first whether boron influenced survival of the gastrointestinal nematode Heligmosomoides bakeri. Female Balb/c mice were fed deficient (0.1 mug B/g), marginal (2.0 mug B/g) or control (12.0 mug B/g) diets, and infected with third-stage larvae. Although liver boron concentrations did not differ among diet groups, dietary boron deficiency impaired survival of the parasite and modulated a broad range of cytokines and chemokines. On the other hand, infection history altered liver mineral concentrations. Second, we examined whether elevated boron concentrations would exert toxic effects on H. bakeri in vitro. Boron toxicity was evidenced by reduced motility, fecundity, infectivity and survival. Feeding stages and free-living stages were more sensitive than non-feeding stages and parasitic stages respectively in a dose-dependent manner.

The factors affecting the accumulation of nitrate in kikuyu grass pastures and the effect of elevated nitrate levels upon digestion in the ruminant were investigated. A high potassium level in the soil seems to be the major factor stimulating the accumulation of excessive amounts of nitrate in kikuyu grass, when the nitrate content of the soil is also high. The continuous elongation of kikuyu grass tillers allows constant exposure of high nitrate containing stem tissue to the grazing ruminant. Digestibility studies in vitro showed that nitrite, formed during the assimilatory reduction of nitrate to ammonia, reduces cellulose digestion, but the degree of reduction also depends upon the presence of readily available carbohydrates and protein in the digest. Studies in vivo showed that the microbial population can adapt to metabolise high concentrations of nitrate (500 mg% N, m/m) in fresh kikuyu grass, without the accumulation of nitrite in the rumen. However, introduction into the rumen of nitrite in excess of the capacity of the nitrite reducing microbes, causes nitrite accumulation. Nitrite has no direct effect upon rumen cellulase activity. Due to the affinity of rumen carbohydrases for the substrate, attempts to isolate these enzymes by means of isoelectric focusing and other separation techniques met with limited success. Nitrite strongly reduces the xylanolytic, total and cellulolytic microbial numbers with a concomitant decrease in xylanase and cellulase activity of the digest. Decreased microbial numbers could not be .attributed to a less negative redox potential of the digest in the presence of nitrite, nor could the effect upon the cellulolytic microbes be attributed to an effect of nitrite on branched chain fatty acid synthesis required for cellulolytic microbial growth. A study of the effect of nitrite upon the specific growth rate of pure cultures of the major cellulolytic bacteria, Ruminococcus flavefaciens strain FDI, Butyrivibrio fibrisolvens strain Ce 51, Bacteroides succinogenes strain S 85 and Ruminococcus albus strain 22.08.6A and the non-cellulolytic bacterium Selenomonas ruminantium strain ATCC 19205 revealed the extreme sensitivity to nitrite of some of these bacteria and the relative insensitivity of others. Growth inhibition seems to depend primarily upon the extent to which these microbes derive their energy from electron transport-mediated processes. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1985.

Includes bibliographical references (leaves 226-261). / xxiii, 261 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Investigates nitrogen utilization in some species of rumen bacteria with the object of understanding the role of ammonia versus exogenous amino acids in relation to microbial growth. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Science, 1996?

Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on February 13, 2008) Vita. Includes bibliographical references.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 136-148). Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 136-148). Also available on the Internet.

Concentrations of trace minerals within the body are known to impact reproductive processes. Thus, the current study analyzed the effects of using an injectable trace mineral supplement containing selenium, zinc, copper, and manganese during a superovulation protocol on embryo outcomes in donor beef cows and further effects on pregnancy rate in recipient females. We hypothesized that an injectable trace mineral (TM) supplement provided to cows fed to meet known nutrient requirements would increase TM status and influence superovulation, embryo characteristics, and enhance pregnancy rates. Our findings indicate that the injectable TM increased concentration of Se within the liver. However, superovulatory response, embryo production, quality grade, and developmental stage were not influenced by TM status. In addition, embryo treatment did not influence pregnancy rate, gestation length, or calf body weight.

The concentrations of calcium and phosphorus were determined in 12 llamas from the Condoriri Agricultural Experiment Center (Oruro Technical University) of Oruro, Bolivia during two seasons (wet and dry) and at three ages (newborn, juvenile, and adult). Samples of flesh were taken from the arm, leg, back, rib, and neck. Pasture samples (grassland and prairie) were used to determine the rate of biting of each animal studied. The blood samples were taken by extracting blood from a jugular vein. The minerals (Ca and P) in the flesh are highest in the wet season, 113.78 mg/100 g. The newborns were found to have the highest concentrations of minerals during the wet and dry season, 113.78 and 93.98 mg/100 g. The mineral concentrations of calcium and phosphorus for the newborns and adults were 120.58 and 144.5 mg/100 g. The lower concentration of juveniles had 7.52 mg/100 g of calcium in the meat and reported a 9.59 mg/100 g concentration during the wet season and 6.78 mg/100 g for the dry season. The juveniles and adults recorded higher concentrations of calcium with 9.2 and 8.78 mg/100 g with the newborns having a lower value of 6.58 mg/100 g. The phosphorus in the flesh was reported to be 9.59 mg/100 g for the wet season and 6.78 mg/100 g for the dry season. The concentration of the calcium and phosphorus in the grazed pasture during the wet and dry seasons was 0.56 and 0.12 % respectively. The females recorded higher concentrations of calcium and phosphorus with 0.38% while the males recorded only a 0.30% concentration. The calcium content is higher in the pasture (0.55%) than the phosphorus (0.13%). In the wet season the biomass contains 0.91% calcium and 0.22% phosphorus. During the dry season the high calcium content was 0.19% and for phosphorus it was 0.04%. The calcium and phosphorus exist in smaller quantities in the blood during the wet season (7.25 mg/dl) and greater quantities during the dry season (9.88 mg/dl). Juvenile females have a higher quantity of calcium (10.15 mg/dl) while newborns and adults have a lower quantity (9.52 and 7.2 mg/dl).

One hundred eight male and 206 female breeder turkeys were fed isocaloric corn-soy rations containing 8, 10 or 12, and 10, 12 or 14'% crude protein, respectively, to which 0.0, 0.1, 0.2, or 0.3% DL-methionine was added in a factorial arrangement of treatments,. With the exception of percentage hen-day egg production and egg size, dietary treatment had no significant effect on the reproduction of females or on the growth of the progeny. Egg production was higher among females fed 12 and 14% protein than among those fed 10% protein. Those fed 14% protein laid the heaviest eggs. Female serum albumin concentrations and the concentrations of blood threonine and lysine significantly increased while concentrations of blood glycine decreased with increased levels of dietary protein. Optimum semen volume and spermatozoa concentration were obtained for males fed 10% protein. For females, the significant response obtained in egg production to increased protein levels and the failure to obtain this response with increased total sulfur amino acid (TSAA) levels as a percentage of total protein, indicates that other amino acids may have been limiting. Based on these results, it appears that for optimum reproduction of Medium White breeder turkeys, a daily intake of at least 22.7 g protein and 696 mg TSAA are necessary for females, and 25.0 g protein and 1,175 mg TSAA are necessary for males. / Master of Science

The effects of dietary energy level (ad libitum vs 75% of ad libitum) and mineral-vitamin intake (100 vs 150% NRC recommendations) on foot and leg development, incidence and severity of foot lesions, soundness scores and metacarpal and metatarsal characteristics of growing boars was studied. Boars assigned to the dietary treatments at 5 wk of age were serially necropsied beginning at 120 d of age. Foot and leg characterization was carried out at four periods (35, 122, 209 and 290 d of age) and at necropsy. Bone samples were obtained at necropsy. Toe measurements increased over time with outside toes larger than inside toes. The hind outside toe was consistently larger than the other toes. Mineral-vitamin level had little effect on toe measurements, while ad libitum feeding produced larger feet and legs as compared with limit-fed boars at an equal age. Correction for body weight differences removed the energy level differences and often produced trends favoring the limit-fed boars. Dietary treatment had little effect on the incidence and severity of pad or horn lesions, however, restricting feed intake produced boars more structurally sound in appearance. Bone size increased with age, while bone ether extract decreased and bone ash content increased. As age increased, Ca content of bone ash increased, P level remained unchanged and Mg, Cu, Zn, Fe and Mn levels decreased. Metatarsals were longer and heavier than metacarpals. Percentage of bone ether extract increased with ad libitum feeding while the 150% mineral-vitamin level resulted in increased percentage bone ash. At an equal age, bone size and mechanical characteristics were greater for ad libitum-fed boars, however, weight-correction produced trends favoring limit-fed boars. Greater bone wall thickness and mechanical characteristics resulted from elevated dietary mineral and vitamin levels. Little consistent correlation was apparent between toe area or volume and the incidence of foot lesions or among the incidence of lesions at the various locations on the front or hind feet. / M.S.