Typescript (photocopy). / Digitized by Kansas Correctional Industries

Orientador: Gisele Zoccal Mingoti / Coorientador: Enilson Geraldo Ribeiro / Coorientador: Fábio Morato Monteiro / Coorientador: Flávia Fernanda Simili / Banca: André Maciel Crespilho / Banca: Roberta Carrilho Canesin / Banca: Joaquim Mansano Garcia / Banca: Letícia Zoccolaro Oliveira / Resumo: As dietas enriquecidas com fontes de ácidos graxos poliinsaturados (AGPs) para touros jovens no período da puberdade a maturidade sexual podem exercer efeito positivo no desempenho reprodutivo. Além disso, selecionar animais jovens de melhor eficiência alimentar (baixo consumo alimentar residual - CAR) é muito importante para os programas de melhoramento genético. Dentro desse contexto, o objetivo do presente estudo foi avaliar os parametros reprodutivos de machos jovens da raça Nelore de baixa e alta eficiência alimentar suplementados com ácidos graxos (AGs) protegidos em regime de pastagem. Foram utilizados 48 machos jovens com média de 14,3±0,13 meses de idade e peso de 389,5±5,43 kg. O delineamento experimental foi inteiramente casualisado em arranjo fatorial 2 x 2 (CAR x suplementação) sendo, 24 animais baixo ou negativo CAR com ou sem suplementação com AGs e 24 alto ou positivo CAR com ou sem suplementação com AGs. As dietas experimentais foram isoproteicas. O período de suplementação foi de dezembro à outubro. Os animais foram mantidos em pastagem de capim-marandu, em lotação contínua e taxa de lotação fixa. As mensurações de características de crescimento, de consumo alimentar, concentrações plasmáticas de metabólitos e hormônios, avaliação andrológica e ultrassonografia testicular foram realizadas a cada 28 dias, dos 14 aos 24 meses de idade. A criopreservação espermática foi realizada na última colheita, momento em que os animais apresentavam 24 meses de idade. Após... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Diets enriched with sources of polyunsaturated fatty acids (PUFAs) for young bulls from puberty to sexual maturity may have a positive effect on reproductive performance. In addition, selecting young animals with better feed intake (low residual feed intake - RFI) is very important for breeding programs. Thus, the aim of this study was to evaluate the reproductive parameters of young Nelore bulls of low and high feed intake supplemented with PUFA in the pasture. The total of 48 young males were used with a 14.3±0.13 months of age and a weight of 389.5±5.43 kg. The experimental design were completely randomized in a factorial 2 x 2 (RFI x supplementation) being 24 animals high RFI with or without supplementation with PUFA and 24 animals low RFI with or without supplementation with PUFA. The diets were isoproteic. The supplementation period was from December to October and the animals were kept in Brachiaria brizantha cv. Marandu pasture in continuous stocking during the experimental period. The measurements of growth characteristics, feed intake, plasma concentrations of metabolites and hormones, andrological evaluation and testicular ultrasonography were performed every 28 days, from 14 to 24 months of age. Sperm cryopreservation was performed it the last collections, at which time the animals were 24 months old. After thawing, computer aided semen analysis (CASA), rapid thermoresistance sperm tests (TTR), integrity of the plasma membrane and acrosomal and in vitro embryo pro... (Complete abstract click electronic access below) / Doutor

Thesis (M.Sc. (Anatomy))--Mahidol University, 1984.

Orientador: César Roberto Esper / Banca: Paulo Henrique Franceschini / Banca: Vera Fernanda Martins Hossepian de Lima / Banca: Rogerio Taveira Barbosa / Banca: Rubens Paes de Arruda / Resumo: Três grupos de 8 touros, sendo cada grupo formado por 4 animais da raça Simental (Bos taurus taurus) e 4 da raça Nelore (Bos taurus indicus), perfazendo um total de 24 touros com idade aproximada de 30 meses foram submetidos a dietas isoenergéticas com diferentes níveis de proteína degradável no rúmen e água ad libitum. As rações foram constituídas basicamente de feno de Tifton 85, farelo de soja, milho e uréia (Nitrogênio Não Protéico) e formuladas individualmente para cada touro de acordo com a análise bromatológica dos ingredientes, peso e ingestão dos animais. Na dieta do grupo controle (C) foram seguidas as normas do NRC (1996) para nutrição de touros em reprodução. Na dieta do grupo "gradual" (G) foram acrescidas 30% e, após quatro semanas, 75% de proteína degradável em relação à dieta controle, através do aumento na quantidade fornecida de uréia (NNP). Na dieta do grupo "Choque" o nível de proteína degradável foi 110% superior à ração do grupo controle durante todo o período experimental. Os touros permaneceram em baias individuais e após o período de adaptação de 21 dias foram submetidos semanalmente a colheitas de sêmen. O sêmen dos animais foram obtidos por eletroejaculação e avaliados quanto aos exames físicos do sêmen (turbilhonamento, motilidade, vigor e concentração) e morfologia espermática durante o período experimental de 15 semanas. Foram realizadas colheitas semanais de sangue 2 horas após a alimentação dos animais com a finalidade de mensurar os níveis plasmáticos de amônia e uréia durante seu pico de produção. Os ejaculados dos touros dos grupos tratados (Cq e G) apresentaram menor turbilhonamento, motilidade, vigor e concentração em relação ao grupo controle (C) a partir da décima terceira semana de experimento (P<0,01). / Abstract: Three experimental groups, each containing eight bulls, were given isoenergetic diets with different levels of ruminal-degradable protein and ad libitum water. Each group was constituted by four Fleckvieh (Bos taurus taurus) and four Nellore (Bos taurus indicus) bulls, in a total of 24 animals with mean age of 30 months. Diets were composed basically of Tifton 85 hay, soy bran, corn and urea (non-proteic nitrogen; NPN) and formulated for each animal individually, according to ingredients' bromatologic analysis, animal's weight and uptake capacity. For the Control-group (C-group) diet, NRC (1996) nutrition recommendations for bulls on reproduction were followed. In the Gradual-group (G-group) diet, 30% more ruminal-degradable protein (compared to the C-group) was added, and after four weeks, the level increased to 75% through the addition of urea (NPN). For the Choque-group (Cq-group), degradable protein level was 110% higher than in Cgroup during all experimental period. Bulls were maintained in individual boxes and after an adaptation period of 21 days, semen samples were collected. Semen was obtained through electroejaculation and analysed for physical (whirl movement, motility, vigour and concentration) and morphological characteristics during the period of 15 weeks. Blood sampling was performed weekly two hours after feeding in order to measure ammonia and ureal levels during its peak production. Treatment groups (Cq-group and G-group) presented lower whirl movement, motility, vigor and concentration than the C-group after the 13th week (P<0,01). Spermatic morphology showed increased levels of greater spermatic defects for taurines (P<0,05) during all experimental period, but no significant differences were observed among treatments for these characteristics. Significant differences in plasmatic urea (P<0,01) occurred. / Doutor

No description available.

The aim of the present study was to determine if the breeding potential of 25-month old, extensively kept, Bonsmara beef bulls can be predicted from production data, spermatozoal characteristics and/or blood hormone concentrations at that age. A further objective of the study was to determine if any of the above mentioned criteria could be associated with the libido of these bulls. Forty-one Bonsmara bulls were included in an on-farm performance test (Phase D1 growth test) for a period of 180 days. At an average age of 24.7 months, blood sampling took place (before and after GnRH treatment) and the bulls were subjected to a libido test, after which further blood samples were collected. Blood sample were analysed for cortisol and testosterone concentrations. The bulls were also subjected to an Overall Breeding Soundness Evaluation. This procedure involves an evaluation of the physical genitalia of the bulls, a measurement of scrotal circumference and semen evaluation. For purposes of statistical analyses the bulls were categorised into independent breeding potential categories according to the scores they obtained for the measured reproductive traits. The categories included scrotal circumference, spermatozoal morphology and motility and the overall breeding soundness category. A statistical analysis of the data was done by using the general linear models (GLM) procedure of the Statistical Analyses System (SAS version 8.2 BMDP). The production and growth measurements of the Bonsmara bulls did not differ between any of the high and low fertility categories and can not be used to predict the breeding potential of young bulls. The correlation between pre-weaning growth rate and the percentage morphologically normal spermatozoa was positive (r = 0.33; P<0.1), suggesting that relatively high growth rates before weaning may have a positive effect on potential fertility under normal extensive feeding conditions. By contrast, numeric differences in growth after weaning suggest that a high growth rate after weaning may have a negative effect on potential fertility. The results showed that the overall breeding soundness categories tended to be influenced by the pre-weaning growth rate (r = 0.24; P>0.1) and body lengths (r = 0.18; P>0.1) of bulls. Sampling time had a statistically significant effect on blood cortisol and testosterone concentrations for all of the breeding potential categories. Testosterone concentration increased significantly (P<0.001) after GnRH treatment. High plasma cortisol concentrations were associated with low plasma testosterone concentrations. High testosterone concentrations were associated with less spermatozoal morphological defects (r = - 0.21; P>0.1). The testosterone concentrations before GnRH treatment was higher for bulls with exceptional fertility (P<0.05), while testosterone concentration after GnRH treatment tended to be higher (P<0.1) for the bulls with acceptable fertility. This observation may be explained by the negative feedback system that operates between LH and testosterone secretion. The percentage spermatozoal defects were influenced to a greater extent by morphological abnormalities leading to reduced motility of the sperm than by any other abnormalities. From the results it seems that the semen morphology category is a better indicator of semen quality than the SC and semen motility categories. Overall breeding soundness classifications of bulls were largely influenced by spermatozoal motility (P<0.001) and to a lesser extend by spermatozoal morphology and SC. None of the reproductive and production measurements showed a correlation with libido scores, implying that optimal bull reproductive evaluation should include the assessment of both breeding soundness and libido. / Dissertation (MSc(Agric))--University of Pretoria, 2009. / Animal and Wildlife Sciences / unrestricted

No description available.

Profiles for testosterone (T), androstenedione (A), dehydroepiandrosterone (DHEA), and progesterone (P) in bovine semen were established for a group of four post-pubertal bulls by depleting the bulls' extra-gonadal sperm reserves (EGR) on three occasions at two week intervals. Each depletion consisted of 14 consecutive ejaculates combined into five pools to reduce variation and to provide adequate volume for steroid radioimmunoassay. Concentration of T and A in semen decreased significantly during depletion and reached basal concentrations. Basal concentrations were regarded as those amounts continually being produced and were considered to have been reached if there were no significant decreases in these concentrations for two or more successive pools. Testosterone concentration decreased from a mean (±SE) of 1.09 (±.17) ng/ml for the first two ejaculates (pool 1) to .26 (±.04) for ejaculates 11 to 14 (pool 5). Decreases in DHEA and P with depletion of EGR were not significant. Only T concentration was similar for pools 4 and 5, but repeatability was dependent on EGR depletion. A difference of approximately .4 ng T/ml was required to establish a significant difference among bulls in this study. Seminal T concentration decrease was not accompanied by a corresponding decrease in seminal fructose concentration nor were any other semen quality characteristics related to seminal T concentration. / M.S.

Three statistical methods - multiple and linear regression, and analysis of variance - were used to interpret the data in this study. The results of a preliminary study indicated that there were several major sources of variation in the non-returns of bulls. These were seasonal differences, possible breed differences, and differences between bulls within a breed. In addition, there were differences in breeds in different seasons. Upon consideration of these data a regression study of 33 bulls was undertaken to ascertain the degree of relationship between the changes in the early and late non-returns to first services. Statistically, it was found that when both the 60-90 day and 30-60 day non-returns are available, the latter are of little practical value in predicting the changes in the 150-180 day non-returns. When only the 30-60 day figures are available they may be used with reasonable accuracy to “estimate” the final changes in the 150-180 day non-returns. An analysis of variance of the errors of estimate from the regression studies indicated that there are several assignable causes of variation in non-return estimates. These include differences between breeds as to the effect of season on reproductive efficiency, differences between bulls within a breed, and a significant difference in seasonal effect in different stations. The use of non-return data in estimating the reproductive efficiency of a bull is of value only when all factors that affect this reproductive efficiency are considered. This investigation shows the significance of some of the various factors to be considered. / Master of Science

Five experiments were conducted to characterize a discontinuous bovine serum albumin (BSA) gradient and to determine its ability to isolate highly viable, morphologically normal, Y-chromosome-bearing bovine spermatozoa. The column consisted of a 500 ml separatory funnel in which 26 ml of extended semen was layered on top of a discontinuous gradient of 4% BSA (60 ml) over 10% BSA (60 ml). Results indicated that the greatest percentage of the applied semen was recovered from the bottom 20 ml of the gradient (fraction 6) when 1 x 10⁹ sperm cells were applied to the column. The column was able to exclude spermatozoa with midpiece and tail abnormalities but sperm cells with head abnormalities were similar in frequency in separated and unseparated semen. Semen isolated from fraction 6 was more viable and more resistant to damage by freezing and aging than semen from the top fractions of the column. The proportion of Y-chromosome-bearing spermatozoa isolated form fraction 6 did not differ from the proportion in unseparated semen. Cows inseminated with separated semen and unseparated semen gave birth to similar proportions of male and female calves. / Master of Science