Call number: LD2668 .T4 1961 S87

Call number: LD2668 .T4 1979 L37 / Master of Science

Call number: LD2668 .T4 1965 M43 / Master of Science

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 107-118). Also available in electronic version.

This study evaluated the effects of an antibiotic (oxytetracycline HCL) on reproductive performance of turkey breeder hens. The antibiotic was administered in 1) drinking water or 2) drinking water and intravaginal infusion. Hens were assigned to fertility subclasses (low 0-70%, medium 71-90%, high 91-100%) based on performance from the 7th to 10th week of production. Hens receiving antibiotic in drinking water showed significantly higher apparent fertility than untreated controls, but had significantly higher early embryonic mortality than hens receiving antibiotic in water plus intravaginal infusion. In order to determine the duration of the effect of antibiotic treatment on the variables under study, the eggs were divided into two periods; one containing eggs laid during treatment periods and one week following treatment periods, and the second containing eggs laid two to four weeks post-treatment. The antibiotic in drinking water significantly improved hatchability during the treatment period. The antibiotic in drinking water plus intravaginal infusion had its greatest effect in reducing early embryonic mortality. This treatment had a longer term effect holding embryonic mortality below 10% during treatment and post-treatment periods, while a shorter term effect was observed when antibiotic was administered only in drinking water. In the latter case early embryonic mortality increased significantly during the post-treatment period compared to the treatment period. No correlation was found between mycoplasmal or bacterial population and fertility subclass or antibiotic treatment. Hen day and hen housed production, body weight, feed consumption, feed consumed per egg, egg weight and specific gravity were unaffected by antibiotic treatment. / M.S.

Supplementation of the diet with low concentrations of antibiotics stimulates the growth of poultry by affecting the intestinal flora. The bacterial flora of the small intestine of turkey poults was extensively analyzed in an attempt to correlate changes in populations with growth response. Lactobacillus species comprised almost 100% of the duodenal flora of two-week-old poults but there was no difference in species associated with antibiotic (zinc bacitracin, 55 ppm) treatment. The ileal flora also was predominantly lactobacilli (average 75% of the flora). The most common lactobacilli from the turkey intestinal tract were several previously undescribed Lactobacillus species followed by L. acidophilus, L. salivarius subsp. salivarius, L. fermentum, and L. plantarum. Antibiotic treatment resulted in a shift in the proportions of several of the unnamed Lactobacillus sp. Preliminary feed trials using two strains of lactobacilli that belonged to species that increased in numbers with antibiotic treatment did not stimulate growth when one-day-old birds were colonized with the strains. A probable explanation for the increase in growth is the effect of antibiotic treatment on the multiplication of bacteria in the small intestine. As the digesta move from the gizzard to lower ileum an average 16-fold increase in bacteria occurs in untreated birds. In antibiotic-treated birds the increase was only 2-fold. This inhibition of growth is not due strictly to cell lysis because there are no significant differences in microscopic counts, but the viable counts do decrease. As a corollary there is significantly less lactic acid in the lower ileum of antibiotic-fed birds. Antibiotics did not affect total microscopic or viable counts in the crop or ceca. The above experiments were all done with zinc bacitracin; however, the inhibition of bacterial multiplication was also observed with procaine penicillin. The conclusion from my data is that zinc bacitracin, and probably procaine penicillin, stimulate the growth of turkey poults by a general suppression of the small intestinal flora rather than by an effect on any individual bacterial species. / Ph. D.

Call number: LD2668 .T4 1963 S56 / Master of Science

Call number: LD2668 .T4 1984 G37 / Master of Science

Call number: LD2668 .T4 1984 S876 / Master of Science

Orientador: Maria Cristina Thomaz / Banca: Fábio Henrique Lemos Budino / Banca: Luciano Hauschild / Resumo: A utilização de prebióticos na nutrição animal vem sendo amplamente estudada, uma vez que a utilização de antimicrobianos está restrita e/ou banida de vários países. Dentre estes, destacam-se os oligossacarídeos de parece celular de levedura, mananas e glucanas, os quais têm seus efeitos ainda não totalmente esclarecidos sobre a nutrição de leitões desmamados. O objetivo do estudo foi avaliar o efeito da inclusão de mananas e glucanas na dieta de leitões recém-desmamados, dos 24 aos 66 dias de idade, sobre o desempenho, incidência de diarreia, tempo de trânsito gastrintestinal, e características morfofisiológicas e microbiológicas do trato gastrintestinal [pH, concentração de ácidos graxos de cadeia curta (AGCC), ácido lático, análise microbiológica e estrutura do intestino delgado]. Foram utilizados 96 leitões desmamados aos 24 dias de idade (7,7 ± 1,76kg), distribuídos em um delineamento em blocos casualizados de acordo com os tratamentos: Controle positivo: dieta com antimicrobiano (40ppm de sulfato de colistina, na 1ª fase); Controle negativo: dieta sem adição de aditivos; N+CA: Controle negativo com adição de 0,10% de MOS e 0,18% de β-glucano; N+CB: Controle negativo com adição de 0,036% de MOS e 0,040% de β-glucano; com 8 repetições por tratamento e 3 animais por unidade experimental. A suplementação com MOS e β-glucano não influenciou (P>0,05) as variáveis de desempenho, microbiologia, AGCC, ácido lático e o tempo de trânsito gastrintestinal. Os animais do tratamento CN apresentaram as menores (P<0,05) alturas de vilosidades no duodeno e jejuno. Os leitões do tratamento N+CA apresentaram maiores (P<0,05) alturas de vilosidades no duodeno, comparados aos do CP. Para a variável profundidade de cripta, os leitões do tratamento CN apresentaram os maiores valores (P<0,05) no duodeno, e para o jejuno, aqueles que receberam N+CA e N+CB... / Abstract: The use of prebiotics in animal nutrition has been extensively studied, since the use of antimicrobials is restricted and/or banned in many countries. Among these, we highlight the oligosaccharides from yeast cell wall, mannans and glucans, which have uncleared effects on nutrition of weaned piglets. The aim of the study was to evaluate the effect of inclusion of mannans and glucans in the diet of weanling pigs, from 24 to 66 days of age on performance, diarrhea incidence, rate passage of digesta, and morphophysiological and microbiological characteristics of the gastrointestinal tract [pH, concentration of short-chain fatty acids (SCFA), lactic acid, microbiological analysis and structure of the small intestine]. It was used 96 newly weaned piglets at 24 days old (7.7 ± 1.76kg), distributed in a randomized block design according to the treatments: Positive control: diet with antimicrobial (40ppm of colistin sulfate, in the first phase); Negative control: diet free of antimicrobial and prebiotics; N + CA: negative control with the addition of 0.10% MOS and 0.18% β-glucan; N + CB: negative control with the addition of 0.036% MOS and 0.040% β-glucan; with 8 replicates per treatment and 3 animals each. Supplementation with MOS and β-glucan did not influence (P>0.05) the performance variables, microbiology, SCFA, lactic acid and gastrointestinal transit time. The animals of CN treatment showed lower (P<0.05) villus height in the duodenum and jejunum. The piglets fed N+CA treatment showed higher (P<0.05) villus heights in the duodenum, compared to those of CP. For the variable crypt depth, the piglets of CN treatment showed the highest values (P<0.05) in the duodenum, and in the jejunum, those fed N+CA and N+CB had lower (P<0.05) crypt depths, compared to those fed CP and CN, and animals fed CP had lower (P<0.05) than those of CN. The AV:PC ratio was higher in the duodenum, for the animals fed N+CA ... / Mestre