京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第18659号 / 農博第2088号 / 新制||農||1027(附属図書館) / 学位論文||H26||N4882(農学部図書室) / 31573 / 京都大学大学院農学研究科応用生物科学専攻 / (主査)教授 廣岡 博之, 教授 松井 徹, 教授 久米 新一 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Cattle ranching has been of major significance to Florida since the 16th century; however, few are aware of the historic, ecologic, economic and cultural influence of this industry. This study investigates the origins and impacts of the traditional customs and practices of Florida’s cattle ranchers, who preserve and reinvent this rich heritage today. Ranchers live closely with the land and their animals and, due to the often-uncertain and cyclical nature of the business, must possess resourcefulness and initiative to prosper. The image of the stoic cowboy has long been associated with the American West, yet before longhorn cattle ever crossed the western plains, Florida frontiers were populated with herds of unique “cracker” cows, descendants of cattle left behind by early Spanish settlers. Like the West, Florida experienced conflicts between ranchers and other land claimants, issues that continue in the 21st century. Modern ranchers contend with developers, environmental concerns, and increasing regulation, yet they persevere in passing on their cultural heritage. Agricultural lifestyles can be emotionally fulfilling, but stewardship of land and animals can be stressful and labor-intensive. Motivation to continue these customs may be enhanced by identification with cowboys of popular American media, enhanced by physical immersion in a similar setting. Optimal agricultural practices have been well researched; however, anthropology provides a useful lens to examine customs and practices of Florida’s cattle ranchers. Anthropologists have long been concerned with the dynamic relationship between human culture and the environment, examining how the physical landscape and ecological niches shape and are shaped by those who inhabit them. As globalized trade markets, technology, and economies expand, influencing agricultural practices and destroying natural habitats, diachronic studies of changing environments, economic and sociocultural influences in geographically bounded locales can be helpful in understanding this process. iv However, a key consideration is the fact that culture is not static, but ever changing, thus the most important aspects of tradition and heritage that we choose to retain and reinvent may provide the most telling insight into any society

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Four multiparous Holstein cows, averaging 44 days in milk and previously fitted with rumina1 and duodenal cannulae, were utilized in a 4 x 4 Latin square design to evaluate effects of dietary nonfibrous carbohydrate (NFC) and rumen undegradable protein (RUP) on metabolic and lactational parameters. Diets were isonitrogenous (17.4% CP) and structured in a 2 x 2 factorial arrangement with levels of NFC at 41 or 47% of dietary OM and RUP at 27 or 41% of dietary CP with inclusion of corn gluten meal, fish meal, and feather meal to increase dietary RUP. When cows were fed diets containing 47% NFC, intake of DM, OM, NFC, and N increased (P ± .05) while those containing 41 % NFC increased (P±.01) intake of NDF and ADF. Ruminal digestibility coefficients were not affected leading to greater quantities of NFC digested resulting in suppressed pH (P ±.01) and acetate (P ±.05) and increased propionate (P ± .05), Diets containing 27% RUP increased (P ±.01) ruminal ammonia and plasma urea nitrogen (N) with 41 % NFC eliciting higher ammonia N concentrations at each RUP level. Bacterial yields (averaging 220 g/d) were slightly higher when 41% NFC diets were consumed with no dietary effects on efficiency. Flow of ammonia N to the small intestine (SI) increased (P ± .01) with 27% RUP. When compared to 41% NFC, diets containing 47% NFC increased (P ± .05) flow of methionine (38.6 vs. 32.5 g/d). Fifty percent of the essential amino acids entering the SI were of bacterial origin. Diets containing 41% RUP elicited lower total tract digestion of N while enhancing that of hemicellulose. Total tract digestion of NFC and ADF was greater when 41% NFC diets were consumed. Yields of milk (38.7 vs. 37.7 kg/d) and lactose (1.94 vs 1.88 kg/d) increased with 27% RUP. Efficiency of production was increased by both 41% NFC and 27% RUP. Total and whey N in milk increased (P 5 ±.05) while milk urea N decreased (P ± .01) with higher (41%) dietary RUP. Increased (P ± .05) absorption of N (490.4 vs. 461.6 g/d) at the SI occurred with the 47 vs. 41 % NFC diets, respectively, with no effects observed on that retained or excreted in the urine or milk. Although supply of methionine to and the absorption of N from the S1 was greater with the 47% NFC diets, no positive effects were observed on nitrogen balance or milk production. Rather, dietary RUP provided greater promise in that lower dietary RUP increased milk production and efficiency while increased RUP enhanced milk N content. Therefore, economics regarding feed costs as well as price for milk and milk components may largely dictate preferential dietary RUP content. Abbreviation key: ADC = apparent digestion coefficient, CGM corn gluten meal, CRN = carbon hydrogen nitrogen, CHO = carbohydrate, CNCPS = Cornell Net Carbohydrate and Protein System, MUN = milk urea nitrogen, N = nitrogen, NAN = nonammonia N, NANMN = nonammonia nonmicrobial N, NFC = nonfibrous carbohydrate, NPN = nonprotein N, PUN = plasma urea N, RDP = rumen degradable protein, RUP = rumen undegradable protein, SI = small intestine, TDC = true digestion coefficient, 41:27 = 41% NFC and 27% RlUP, 47:27 = 47% NFC and 27% RUP, 41:41 = 41% NFC and 31% RUP, 47:41 = 47% NFC and 41% RUP. / Ph. D.

The purpose of this investigation was to study the influence of the ration of the cow upon the vitamin C content of milk. The determinations were made by the biological assay method and by the chemical titration method. The cows were given four kinds of rations. Similar determinations have been made by other workers. A brief resume of their technique and conclusions follows: From the results of this investigation, it is concluded: 1. That the ascorbic acid content of milk decreases as the stage of lactation increases. 2. That the ascorbic acid of the milk of individual cows varies within the breed. 3. That the age of the cow does not influence the vitamin C content of the milk. 4. That the rate of gain of the assay animals over a period of 74 days was independent of the ascorbic acid content. 5. That the vitamin C content seems to be independent of the ration of the cow. 6. That the “spring milk” carried some factor which influenced a greater gain of weight than other “winter” milk rations. / Master of Science

Some cattle producers have reported metabolic disturbances in beef cows fed high levels of broiler litter. Therefore, an experiment was conducted to evaluate mineral metabolism of beef cows fed different levels of broiler litter. Sixty Angus-Hereford crossbred cows ranging in age from 3 to 12 yr were blocked by age, BW, and stage of gestation, and randomly allotted within blocks to three diets: 1) mixed hay, full-fed; 2) 4.1 kg of a mixture of 80% broiler litter and 20% cornmeal plus mixed hay (low-litter diet); and 3) 8.2 kg of the 80% litter and 20% cornmeal mixture plus mixed hay (high-litter diet). Cows fed the litter diets were fed 57 g of magnesium oxide per head per day in the litter-corn mixture. Cows fed the three diets had access to a high-Mg mineral mixture. Experimental diets were fed from January 4, 1995 to April 19, 1995, and calving began on March 15. There were no physical signs of metabolic disturbances in any of the cattle. Blood serum Ca decreased and P levels increased in the cows fed both levels of broiler litter after the first 28 d on experiment. On d 28, average serum Ca values were 8.5 mg / dL for the cows fed hay, compared to 7.9 and 7.6 mg / dL for those fed the low and high levels of litter, respectively (P < .01). The average serum P values were 5.7, 8.2, and 9.1 mg/dL, respectively (P < .01). Generally, serum Ca remained lower and serum P remained higher for the cows fed broiler litter until the end of the winter feeding period (105 d). By mid-summer, serum Ca and P were similar (P > .05) for cows that had been fed the three diets. Serum Mg, Cu, and Zn were not affected by feeding litter. Urinary Ca and Mg, expressed as units per unit of creatinine, did not differ (P > .05) among treatments. Serum parathyroid hormone (PTH) was higher (P < .05) in cows fed the lower level of litter than those fed the higher level in April (105 d). Serum PTH values for cows fed hay were intermediate. Birth weights, rate of gain, and weaning weights of calves did not differ among the three diets. Feeding high levels of broiler litter to beef cows appears to affect serum Ca and P. / Master of Science