Thesis (Ph. D.)--Texas A&M University, 2006. / "Major Subject: Poultry Science" Title from author supplied metadata (automated record created on Apr. 27, 2007.) Vita. Abstract. Includes bibliographical references.

Thesis (M. S.)--Texas A&M University, 2005. / "Major Subject: Poultry Science" Title from author supplied metadata (automated record created on Apr. 27, 2007.) Vita. Abstract. Includes bibliographical references.

Thesis (Ph. D.)--Texas A&M University, 2005. / "Major Subject: Poultry Science" Title from author supplied metadata (automated record created on Apr. 27, 2007.) Vita. Abstract. Includes bibliographical references.

Fishy-egg tainting has long been a problem associated with feeding canola meal (CM) to brown-shelled laying hens. It is a classical example of nutrigenetics, as both dietary and genetic factors must be present for a hen to lay fishy-tainted eggs. Trimethylamine (TMA), the compound responsible for the fishy smell, is produced by bacterial fermentation of choline in the lower gut. CM contains large amounts of choline in the form of sinapine. Choline must first be hydrolyzed from sinapine before it can be absorbed or converted to TMA. Normally, the malodourous TMA is metabolized to the odourless trimethylamine N-oxide (TMAO) by flavin-containing monooxygenase 3 (FMO3). A mutation in FMO3 (c.984A>T) prevents TMA from being oxidized to TMAO, and subsequently TMA accumulates in the developing egg yolks. Our objective was to determine the inheritance pattern of fishy-egg tainting when hens are fed canola meal, reflecting typical industry conditions. In the first of two trials, hens of a commercial brown-shelled strain were genotyped at FMO3 c.984A>T and fed graded levels of CM (0, 6, 12, or 18%). These hens were bred to produce a second generation of hens, which were also genotyped and fed graded levels of CM (0, 6, 12, 18, or 24%) or choline chloride (0, 0.055, 0.110, 0.165, or 0.220%). Choline chloride, at levels up to 0.220%, does not lead to the production of fishy tainted-eggs. When fed CM, TT hens laid fishy-tainted eggs. Mean yolk TMA concentration was not significantly different between hens of the AA and AT genotypes, with means from both genotypes remaining below the human detection threshold for all of the dietary treatments. Large day-to-day variations in yolk TMA concentration were seen in hens of all three genotypes. We concluded that fishy-egg tainting is recessive when hens are fed CM at levels reflecting typical commercial practices.

Fishy-egg tainting has long been a problem associated with feeding canola meal (CM) to brown-shelled laying hens. It is a classical example of nutrigenetics, as both dietary and genetic factors must be present for a hen to lay fishy-tainted eggs. Trimethylamine (TMA), the compound responsible for the fishy smell, is produced by bacterial fermentation of choline in the lower gut. CM contains large amounts of choline in the form of sinapine. Choline must first be hydrolyzed from sinapine before it can be absorbed or converted to TMA. Normally, the malodourous TMA is metabolized to the odourless trimethylamine N-oxide (TMAO) by flavin-containing monooxygenase 3 (FMO3). A mutation in FMO3 (c.984A>T) prevents TMA from being oxidized to TMAO, and subsequently TMA accumulates in the developing egg yolks. Our objective was to determine the inheritance pattern of fishy-egg tainting when hens are fed canola meal, reflecting typical industry conditions. In the first of two trials, hens of a commercial brown-shelled strain were genotyped at FMO3 c.984A>T and fed graded levels of CM (0, 6, 12, or 18%). These hens were bred to produce a second generation of hens, which were also genotyped and fed graded levels of CM (0, 6, 12, 18, or 24%) or choline chloride (0, 0.055, 0.110, 0.165, or 0.220%). Choline chloride, at levels up to 0.220%, does not lead to the production of fishy tainted-eggs. When fed CM, TT hens laid fishy-tainted eggs. Mean yolk TMA concentration was not significantly different between hens of the AA and AT genotypes, with means from both genotypes remaining below the human detection threshold for all of the dietary treatments. Large day-to-day variations in yolk TMA concentration were seen in hens of all three genotypes. We concluded that fishy-egg tainting is recessive when hens are fed CM at levels reflecting typical commercial practices.

No description available.

With only six poultry degree granting universities, producing a slim number of graduates each year, poses a challenge for the industry. There may be potential areas for internal recruitment within Colleges of Agriculture and Life Sciences (CALS). In study 1, an evaluation of Mississippi State University’s CALS retention trends determined that Biochemistry (BCH) and Animal Science (AS) have the lowest retention rates. Study 2 compared all six poultry degree granting universities’ CALS retention rates, with AS continuously having one of the lowest retention rates. Lastly, Study 3 surveyed undergraduates, advisors, and faculty showing students having an interest in poultry while advisors and faculty were hesitant in exposing students to opportunities within poultry. Results from these studies unveiled a new population of students for departments within CALS to recruit from, specifically poultry, to potentially increase CALS and university retention rates, thus possibly providing the poultry industry with more qualified employees.

Recruitment efforts are important in a college setting. With only six remaining poultry science departments, they specifically need recruitment to help meet extreme demands for students by the industry. However, little is known about which recruitment efforts are effective or if poultry science majors prefer specific recruitment methods. Chapter II of this dissertation is an assessment of current recruitment practices and enrollment of the six poultry science departments in the U.S. Results revealed that all departments currently have recruitment programs and differences were observed within each. Some were in the budget, time spent recruiting, amount of faculty dedicated to recruitment efforts, and activities utilized in recruitment efforts. Chapter III of the dissertation was a comparison of recruitment programs with student numbers, graduation rates, and student satisfaction. This study was conducted in an attempt to understand which recruitment practices work for a given poultry science department and which department, if any, could benefit from a change. Departments with low enrollment counts had variations in recruitment practices when compared to other departments with higher enrollment counts, such as their perceived effectiveness of FFA national convention, direct mailing and brochures, and hosting 4-H and FFA poultry activities. In Chapter IV, a survey was conducted to determine the influence of factors on student choice among poultry science students. This study determined that conversations with a poultry faculty member or department representative, campus student activities, cost (consist of tuition, room, and board), scholarships, preparation for employment, job opportunities, and high school agriculture teachers were the most influential factors for poultry science students in the decision to major in poultry science. Collectively, these three studies reveal that conversations with prospective students, including campus tours where these conversations can occur, should be utilized. Scholarships, cost, and employment opportunities are also very important to students. Additionally, poultry science department personnel should target FFA events and/or 4-H programs as recruitment opportunities. Other efforts could be used to raise awareness about a poultry science department or poultry science as a major, in general, but might not be effective in recruiting students to a specific department.

Five trials were conducted to assess the nutritive value of high fiber canola meal (HFCM) as a protein supplement for ruminants. Trial one determined the chemical composition of HFCM relative to low fiber canola meal (LFCM) and canola meal in a completely randomized design using samples obtained from five different crushers. In the second trial, the in situ nylon bag technique was used to determine disappearance of dry matter (DMD), crude protein (CPD), neutral (NDFD) and acid (ADFD) detergent fiber from canola meal, LFCM and HFCM samples derived from five different crushers following 24 h of nunen incubation. The effect of crushing plant of origin on in situ nutrient disappearance in the three meals was also determined. In the third trial, rumen nutrient kinetic parameters and effective degradabilities were determined for the blended canola meal, LFCM and HFCM. In situ disappearance of different amino acids canola meal, LFCM and HFCM following 12 h of rumen incubation was determined in the fourth study. The fifth trial was designed to determine nutrient digestibility coefficients by growing lambs of seven diets containing dehydrated alfalfa and 0, 25, 50 and 75% HFCM or canola meal in a randomized complete block design. Milk yield and composition responses of early to mid lactation dairy cows to diets supplemented with HFCM, canola meal or soybean meal were also determined. Results of the first trial indicated that tail-end dehulling of canola meal resulted in more fractionation of fiber than protein between HFCM and LFCM. Results of the second trial showed differences in CPD and DMD within LFCM and HFCM but not within canola meal samples. However, no meal by crusher interaction was observed indicating that in situ nutrient disappearances in the three meals were consistent across crushers. At 5% h^-1 rumen flow rate, effective DM degradability (trial three) was higher (P $<$ 0.05) in LFCM than in canola meal and was higher in canola meal than in HFCM while effective CP degradability was higher in LFCM and canola meal than in HFCM. Effective NDF degradability was higher (P $<$ 0.05) in LFCM than in canola meal and MFCM. However, effective ADF degradability was higher in LFCM than in canola meal and was higher in canola meal than in HFCM. Tail-end dehulling had little effect on in situ disappearance of amino acids from canola meal, LFCM and HFCM following 12 h of rumen incubation. Results from the fifth trial indicated that at 75% inclusion rate, the diet containing HFCM had lower (P $<$ 0.05) DM, CP and gross energy digestibility coefficients relative to canala meal diet. Results of the dairy trial showed no treatment effect on feed intake. (Abstract shortened by UMI.)

This dissertation is the product of two behaviour studies and an in vitro fermentation trial. Both behaviour studies were conducted at the Ashburton Racehorse-Training Centre in Ashburton, near Pietermaritzburg in KwaZulu- Natal. The first behaviour study evaluated differences in behaviours obtained through feeding either twice or four times daily. This trial showed (P<O.OO1) that horses fed twice a day spend a greater proportion of their day in stereotypic or vice-like behaviours. Horses eating four times a day ate less hay (P<O.OO1) and more concentrate (P<O.05) than horses being fed twice a day. Horses in both yards ate more hay (P<O.05) when exercise intensity was increased. Defecation frequency was higher on days when exercise intensity was high (P<O.05) and in the yard where horses were fed four times per day (P<O.O1). Faecal weight was greater (P<O.05), horses lay down more frequently (P<O.05), spent more time eating concentrate (P<O.OO1) and less time eating hay (P<O.OO1) when horses were fed four times per day. Fillies spent more time (P<O.05) eating hay than geldings. The second behaviour study was conducted within one yard only and considered the effects of changes in management strategies on the incidence of stereotypic behaviour. The results did not indicate that changes in management related to exercise intensity would have an effect on behaviours exhibited. However this trial did demonstrate that a reduction in feed intake on days when exercise is reduced will reduce the incidence of stereotypic behaviours. Horses reduced the time spent eating hay when exercise was reduced except that when feeding frequency was reduced in conjunction with reduced exercise, more time was then spent eating hay (P<O.OO1). It was found that fillies spent more time licking surfaces (P<O.OO1) and weaving (P<O.O1) than geldings, which were more aggressive (P<O.OO1) and ate more bedding (P<O.05) than the fillies. All the horses were more alert (P<O.OO1) on days of moderate exercise except when feed was reduced in conjunction with reduced exercise, so that horses were less alert (P<O.OO1) and more time resting (P<O.OO1). The in vitro study was conducted at the department of Animal and Poultry Science at the University of KwaZulu-Natal, Pietermaritzburg. This was a dilution trial, using different ratios of maize and Eragrostis curvula. It was shown that as the proportion of maize in the ration was increased so the digestibility and the degradability of the ration increased (P<O.OO1). It was also shown that the adapted two stage digestion techniques described by Tilley & Terry (1963) had lower supernatant pH levels than the samples that underwent microbial digestion only. This was accounted for by a problem with the methodology. The trial had hoped to show a dramatic decrease in pH and increased rates of gas production when the maize portion of the sample was increased. From the results established during this trial it is clear that application exists in the adoption of this method in in vitro feed analysis in the horse industry.· The behaviour studies significantly linked the incidence of stereotypic behaviour to feeding and nutritional management in racehorses. Some explanations of the noted behaviours can be elucidated through the development of in vitro protocols, where hindgut pH, degradability and fermentation of different ration mixtures elicit responses in physical terms. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.