Este estudo teve como objetivo avaliar o efeito do uso de dois beta-agonistas adrenérgicos (βAA), cloridrato de zilpaterol (ZIL) e cloridrato de ractopamina (RAC), em combinação com a técnica de imunocastração sobre o desempenho, perfil sanguíneo, comportamento ingestivo e características de carcaça de bovinos confinados na fase de terminação. Noventa e seis bovinos machos da raça Nelore, com peso vivo inicial médio de 409 kg ± 50 kg e idade média de 20 meses, foram divididos em dois grupos de 48 animais, no qual metade dos animais de cada grupo recebeu a vacina de imunocastração enquanto que a outra metade não recebeu a vacina. Os animais foram alimentados por 70 dias com uma dieta comum contendo 76% de concentrado e 24% de volumoso (silagem de milho). Após 70 dias de confinamento, os animais foram divididos em três grupos, de acordo com o peso, dentro de cada bloco e condição sexual, e aleatoriamente alimentados com uma das seguintes dietas, pelos 30 dias seguintes: CON - dieta padrão utilizada na fase anterior, sem a adição de βAA; ZIL - dieta padrão acrescida de 80 mg/dia cloridrato de zilpaterol; RAC - dieta padrão acrescida de 300 mg/dia cloridrato de ractopamina. Foi avaliado o desempenho, área de olho de lombo (AOL), espessura de gordura subcutânea (EGS) e espessura de gordura na picanha (EGP), bem como o comportamento ingestivo e a gasometria e o perfil bioquímico sanguíneo. No abate foi avaliado o peso vivo final (PVF), peso de carcaça quente (PCQ) e rendimento de carcaça quente (RCQ). Não houve interação entre os fatores principais para nenhuma característica avaliada. Os animais não-castrados tiveram maior ganho médio diário (GMD) e eficiência alimentar (EA) quando comparado aos animais imunocastrados, além de apresentarem maior PCQ e AOL, porém, sem alterar o RCQ, e menor EGS e EGP do que animais imunocastrados. Animais imunocastrados tiveram maior concentração sérica nas principais variáveis relacionadas ao metabolismo e deposição de gordura, tais como HDL, triglicerídeo, colesterol e ácido graxo não-esterificado. Não houve efeito dos tratamentos nem da condição sexual sobre o comportamento ingestivo dos animais. Os animais suplementados com ZIL foram superiores no GMD, EA, AOL, RCQ, porém, sem alterar o PCQ, e inferiores na EGS e EGP quando comparados a animais CON e RAC. Animais suplementados com ZIL apresentaram concentrações séricas representativas de maior metabolismo e deposição de proteína, tais como menores taxas de ureia e maiores taxas de creatino quinase. Não houve efeito da RAC sobre o CON em nenhuma das características supracitadas. A imunocastração diminui a deposição muscular e aumenta a deposição de gordura na carcaça, enquanto que os βAA aumentam a proporção muscular e diminuem a proporção de gordura, havendo impacto direto no desempenho e nas características e rendimento de carcaça, sem haver interação dessas tecnologias nas características avaliadas, portanto, ambas devem ser avaliadas separadamente. / This study aimed to evaluate the effect of two beta-adrenergic agonists (βAA), zilpaterol hydrochloride (ZH) and ractopamine hydrochloride (RH), in combination with immunocastrion technique on performance, blood profile, feeding behavior, and carcass traits of Nellore cattle in feedlot finishing phase. Ninety-six males Nellore cattle (409 ± 50 kg LW; 20 mo old) were divided in two groups with forty-eight animals and half of them each group received immunocastration vaccine. Animals were fed for 70 days a common diet containing 76% concentrate and 24% roughage (corn silage). Following they were split in 3 groups, according to weight and within block and sex condition, and fed 30 more days one of the following treatments: CON - basis diet without βAA; ZH - basis diet plus 80mg/d zilpaterol hydrochloride; RH - basis diet plus 300mg/d of ractopamine hydrochloride. Performance, loin muscle area (LMA), backfat thickness (BFT), rump fat thickness (RFT), feeding behavior, gas blood, and blood biochemical profile were recorded in the feedlot. Final liveweight (FLW), hot carcass weight (HCW) and dressing percent (DP) were recorded in the harvest. There was no interaction between the main factors for any traits evaluated. Non-castrated animals had higher average daily gain (ADG) and feed efficiency (G:F) compared to immunocastrated animals, besides higher HCW and LMA, however, without changing DP, and lower BFT and RFT than immunocastrated animals. Immunocastrated animals showed greater serum concentration in the main variables associated to metabolism and fat deposition, such as HDL, triglycerides, cholesterol, and non-esterified fatty acid. No effect of treatments or sex condition on feeding behavior. The animals supplemented with ZH were higher in ADG, G:F, LMA, DP, however, without altering the HCW, and lower in BFT and RFT compared to CON and RH animals. ZH animals showed serum concentration representative of greater metabolism and muscle deposition, such as lower urea rates and higher creatinekinase levels. There was no effect of RH on the CON in any traits abovementioned. Immunocastration decreases the muscle deposition and increases the fat deposition in the carcass, whereas the βAA increases the muscle proportion and decreases the fat proportion, which has effect on performance, carcass traits and dressing percent, with no interaction of these technologies in the characteristics evaluated, thereby both should be evaluated separately.

Made available in DSpace on 2017-07-10T17:48:18Z (GMT). No. of bitstreams: 1 Vanessa Piovesan.pdf: 2549955 bytes, checksum: c331863bb881e6b31ed4e4f8d5286408 (MD5) Previous issue date: 2009-09-18 / Two commercially available corn varieties of different kernel texture were planted to determine their physical and chemical characteristics. The effects of corn varieties and amylase supplementation on nutrient digestibility and piglet s performance were also studied. Twelve castrated piglets weighing initially around 8 kg were individually housed in metabolic crates to determine nutrient digestibility of three experimental diets: 1) semi dent corn kernel; 2) flint corn kernel, and 3) flint corn kernel + amylase. The performance of piglets was also studied using 75 animals weighing around 8 kg distributed in randomized block design with three treatments and five replications. The treatments studied were the same used in digestibility study. In both corn kernels the chemical characteristics were similar and no different from average values found in others studies. The semi dent corn kernel had lower vitreousness index then flint corn kernel (69.3 and 74.6%, respectively), lower density (1.217 and 1.232 g/cm3, respectively) and lower 1,000-kernel weight (339.5 and 345.0 g, respectively). The protein amount of hard endosperm was higher in the flint than semi dent corn kernel. The results of electronic micrograph have indicated differences in qualitative characteristics of starch structures between corns studied. There was effect of treatments in digestible (DE) and metabolisable energy (ME) of diets being semi dent corn kernel diet had more DE and ME values than flint dent corn kernel diet. The amylase addition increased the DE and ME in flint dent corn diet. The corn kernel characteristics have no influenced feed intake, body gain and feed conversion. Amylase addition has no affected the performance characteristics studied. In conclusion there were differences in physical and chemical characteristics between corn kernels evaluated and diets with semi dent corn kernel have more DE and ME in comparison with flint corn kernel diets, although amylase addition increased energy values of flint corn kernel / Duas variedades comerciais de milho de diferentes texturas foram cultivadas para determinação das características físicas, químicas e microscópicas dos grãos. Foram estudados os efeitos das duas variedades e adição de amilase no metabolismo e desempenho de leitões. No ensaio de metabolismo, 12 leitões machos castrados foram alojados individualmente em gaiolas projetadas para leitões na fase de creche, utilizando-se três tratamentos com quatro repetições e duas fases com delineamento experimental em bloco casualizado sendo que cada animal consistiu em uma unidade experimental. No desempenho utilizou-se setenta e cinco leitões (7,87 ± 0,67 quilos) distribuídos em blocos casualisados com três tratamentos e cinco repetições. Os tratamentos consistiram de três dietas contendo: 1) grãos de milho semi-dentado; 2) grãos de milho duro; 3) grãos de milho duro + amilase. Os grãos de milho semi-dentado tiveram menor valor de vitreosidade que os grãos de milho duro (69,3 e 74,6 respectivamente), menor densidade (1,217 e 1,232 g/cm3, respectivamente) e menor peso de 1.000 grãos (339,5 e 345,0, respectivamente). A quantidade de proteína no endosperma vítreo foi maior nos grãos de milho duro que nos grãos de milho semi-dentado. A concentração de amido, amilose e amilopectina não variaram entre as duas variedades de milho. Os resultados da micrografia eletrônica de varredura confirmam que existem diferenças qualitativas na estrutura do amido nos dois milhos estudados. Quanto ao metabolismo, valores de energia digestível (ED) e energia metabolizável (EM) foram influenciados pelos tipos de milho, sendo o semi-dentado superior ao milho duro. A inclusão de amilase à dieta com milho duro fez com que os valores de ED e EM se aproximassem aos valores obtidos com milho semi-dentado. Conclui-se, portanto com este estudo, que na fase de creche, leitões consumindo milhos de textura semi-dentada e dura apresentam desempenho semelhantes e a adição de alfa-amilase em rações de leitões contendo milho de textura dura não altera o desempenho animal; o endosperma dos milhos semi-dentado e duro apresentam características químicas e físicas diferenciadas; rações formuladas com milho semi-dentado apresentam maior energia que rações formuladas com milhos duros e a adição de amilase contribui para disponibilizar energia das rações contendo milho duro

Made available in DSpace on 2017-07-10T17:48:24Z (GMT). No. of bitstreams: 1 Pryscilla Cenci de Barros.pdf: 261634 bytes, checksum: b86848d5ab9e125579adb6b4c23a23d7 (MD5) Previous issue date: 2010-12-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this study to evaluate the effect od addition of amylase and protease, isolated or in combination on the digestibility of nutrients in diets for piglets in the nursery phase. It was used 16 piglets with initial weight of 8.04 kg were individually penned in metabolism cages. The experimental treatments consisted of four isoenergetic and isolisinic and differed only in addiction or not of enzymes: treatment 1 = control diet; treatment 2 = 0.06% of amylase; treatment 3 = 0.0125% of protease; treatment 4 = 0.06% of amylase and 0.0125% of protease. The experimental desing was completely randomized desing with four replications and two phases. No effect of the inclusion of amylase and protease, alone or combined, in the digestibility of dry matter, organic matter, crude protein, ash, starch and gross energy. it is concluded that supplementation with amylase and protease isolated or in combination in diets for piglets in the nursery phase did not result in improvement of digestibility coefficients of the variables, but when nalyzing the phases separately, the digestibility coefficients were higher in the phase 2 in all treatments / Objetivou-se com este estudo avaliar o efeito da adição das enzimas amilase e protease, isoladas ou combinadas, sobre a digestibilidade dos nutrientes de rações para leitões na fase de creche. Utilizaram-se 16 leitões machos castrados com peso vivo médio inicial de 8,04 quilos os quais foram alojados individualmente em gaiolas de metabolismo. Os tratamentos experimentais consistiram de quatro rações isoenergéticas e isolisínicas que diferiram apenas na adição ou não de enzimas: tratamento 1 = ração controle; tratamento 2 = 0,06% de amilase; tratamento 3 = 0,0125% de protease; tratamento 4 = 0,06% de amilase e 0,0125% de protease. O delineamento experimental utilizado foi o delineamento inteiramente casualizado, com duas fases e quatro repetições por fase. Não houve efeito da inclusão de amilase e protease, isoladas ou combinadas, nos coeficientes de digestibilidade da matéria seca, matéria orgânica, proteína bruta, matéria mineral, amido e energia bruta. Conclui-se que a suplementação com amilase e protease isoladas ou em combinação em rações para leitões na fase de creche não resultou em melhora dos coeficientes de digestibilidade das variáveis estudadas, porém ao analisar-se as fases separadamente, os coeficientes de digestibilidade foram superiores na fase 2 em todos os tratamentos

Made available in DSpace on 2016-08-17T17:11:03Z (GMT). No. of bitstreams: 1 DISSERTACAO_MAYANNA KARLLA LIMA COSTA.pdf: 1242952 bytes, checksum: 59b9810ed129f3e0ae5fd5724a34dfe3 (MD5) Previous issue date: 2014-08-27 / The objective was to evaluate the nutritional value of varieties of sugar cane as a function of nitrogen fertilization. The varieties used were RB 863129, RB 867515 and RB 92579 and the nitrogen doses were 0, 60, 80, 120 and 140 kg ha-1. The experiment was divided in two stages: in the stage we evaluated the productivity and nutritional quality of three varieties of sugar cane (I Year - plant cane), and in the second stage (Years II and III) we evaluated the influence of nitrogen fertilization on the nutritional quality of the first and second ratoon of the same sugar cane varieties. For the analysis of productivity and other parameters, one collection of plant material was performed at the end of each experimental. The laboratory analysis consisted in the dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and (DMIVD) digestibility. In plant cane were also determinations of Brix and ratio NDF/Brix. For the plant cane, in terms of productivity in t ha-1, percentage of DM and CP, we observed a better values (P<0.05) for the RB 863129, and there was no significant difference between varieties (P <0.05) for the NDF, ADF and DMIVD. The three varieties evaluated showed reasonable chemical composition for ruminant nutrition and in vitro digestibility greater than 60%. The first and second ratoon all parameters differed (p<0.05) between varieties and fertilization, with the exception of DM content and in vitro digestibility occurring in most cases significant interaction between varieties, treatment and years of cutting. The variety RB 92579 presented at the two brass knuckles better productivity (a 131 t ha-1 of stalks) coupled with the best nutritional parameters (26% of ADF, 41% NDF, 2,44% CP and 69 DMIVD). The productivity of cane sugar, as well as its nutritional quality may suffer any increase or decrease according to the year and cutting management established in relation to nitrogen fertilization, moreover, the observed responses were influenced by varieties in most parameters assessed. / Objetivou-se avaliar o valor nutritivo de variedades de cana-de-açúcar em função da adubação nitrogenada. As variedades estudadas foram RB 863129, RB 867515 e RB 92579, e as doses nitrogenadas 0, 60, 80, 120 e 140 kg N ha-1. O experimento foi dividido em duas etapas, sendo que na primeira etapa avaliou-se a produtividade e qualidade nutricional de três variedades de cana-de-açúcar (Ano I - cana-planta), e na segunda, (Anos II e III) avaliou-se a influência da adubação nitrogenada na qualidade nutricional da primeira e segunda soca das mesmas variedades. Para a análise de produtividade e os demais parâmetros foram feitas três coletas de material vegetal, uma a cada final de ano experimental. Determinou-se os teores de matéria seca (MS), e, com base na MS, proteína bruta (PB), fibra em detergente neutro (FDN), fibra em detergente ácido (FDA) e digestibilidade in vitro da matéria seca (DIVMS). Na cana-planta foram determinados o teor de Brix e a relação FDN/Brix. Para a cana-planta, a produtividade (t ha-1) e os teores de MS e PB, foram superiores (P<0.05) para a variedade RB 863129. Não houve diferença (P<0,05) entre as variedades para os teores de FDN e FDA e para a DIVMS. As três variedades avaliadas apresentaram composição química razoável para nutrição de ruminantes e digestibilidade in vitro maior que 60%. Na primeira e segunda soqueira houve diferença (P<0,05) entre variedades e doses de adubação para os parâmetros avaliados, com exceção do teor de MS e digestibilidade in vitro, que foram influenciados (P<0,05) pelas variedades, doses de N e anos de corte. A variedade RB 92579 apresentou nas duas soqueiras a melhor produtividade (131 t ha-1 de colmos), aliada aos melhores parâmetros nutricionais (FDA 26%, FDN 41%, PB 2,4% e DIVMS 69,4%). A produtividade da cana-de-açúcar, assim com a sua qualidade nutricional, pode ser influenciada de acordo com o ano de corte e o manejo estabelecido em relação à adubação nitrogenada, além disso, as respostas observadas foram influenciadas pelas variedades na maioria dos parâmetros avaliados.

Dois experimentos foram conduzidos de forma semelhante, variando apenas a idade do lote de matrizes Ross que originou os ovos (42 e 60 semanas de idade, respectivamente, para os experimentos 1 e 2), com o objetivo de avaliar o desempenho de pintos oriundos de ovos leves e pesados, alimentados com dietas pré-iniciais de diferentes formas físicas e níveis nutricionais.. Foram incubados ovos apresentando peso médio de 59,0 e 70,8 g, respectivamente, para o experimento 1 (tendo originado pintos de 41,0 e 49,0g de peso médio) e 66,9 e 75,1g (tendo originado pintos de 46,2 e 52,1g de peso médio), respectivamente, para o experimento 2. Uma parte destes ovos teve o peso de seus componentes determinado. À eclosão, 288 pintos, metade de cada categoria de peso de ovo, foram distribuídos em um delineamento inteiramente casualizado, em 48 parcelas. Cada parcela alojou seis pintos, metade de cada sexo. Os tratamentos experimentais obedeceram a esquema fatorial 2x3 (2 pesos de ovos x 3 tipos de rações préiniciais). Utilizaram-se três dietas de formulação comercial na fase pré-inicial: ração peletizada, com menor nível energético (2.900 kcal/kg), protéico e de aminoácidos, considerada uma dieta de baixos níveis nutricionais (PBN); ração farelada, de mesma composição nutricional da ração peletizada (FBN); ração farelada, com maior nível energético (2.950 kcal/kg), protéico e de aminoácidos, considerada uma dieta de altos níveis nutricionais (FAN). Foram avaliados o tempo de consumo das dietas pré-iniciais e, aos sete e 14 dias, o ganho de peso, o peso vivo, o consumo de ração e a conversão alimentar. Do término das rações pré-iniciais até os 14 dias de idade, as aves receberam uma mesma ração farelada. Em ambos os experimentos o albúmen foi mais pesado nos ovos classificados como pesados (P<0,05). No experimento 1, a dieta PBN foi consumida mais rapidamente por pintos oriundos de ovos pesados. Aos sete dias, a dieta PBN melhorou o peso vivo, o ganho de peso e a conversão alimentar (P<0,05). Já o peso do ovo influenciou o peso vivo, que foi maior para os pintos oriundos de ovos pesados (P<0,05). O benefício da dieta PBN quanto à conversão alimentar, se manteve aos 14 dias, e o peso vivo dos pintos oriundos de ovos pesados que receberam a dieta PBN foi maior do que aqueles que receberam as dietas FBN e FAN (P<0,05). No experimento 2, não houve diferença significativa para o tempo de consumo das dietas pré-iniciais (P>0,05). Aos sete dias, as dietas PBN e FAN proporcionaram aos pintos melhor conversão alimentar (P<0,05). Porém, aos 14 dias, não houve diferença significativa entre as variáveis (P>0,05). Concluiu-se que, em ovos de matrizes de mesma idade, a diferença no peso dos ovos deve-se ao incremento de albúmen. Quanto ao desempenho, os pintos oriundos de matrizes de idade intermediária foram mais influenciados pelas diferenças de peso dos ovos e composições das dietas, sendo que a dieta peletizada beneficiou o desempenho dos mesmos, mesmo apresentando menor nível nutricional. / Two experiments were conducted to evaluate different pre-starter diets on performance of chickens from light and heavy eggs hatched from Ross breeders of different ages. In the experiment 1, these eggs, that showed weight of 59,0 and 70,8g, were hatched from breeders of 42 weeks of age. In the experiment 2, these eggs, that showed 66,9 and 75,1g, were hatched from breeders of 60 weeks of age. The eggs percentage composition was evaluated. After hatching, 288 day-old chicks, males and females, were weight and allocated in 48 cages. In the experiment 1, their live weight was 41,0 and 49,0g; in the experiment 2, 46,2 e 52,1g. The performance trials were conducted in a completely randomized design with 6 treatments and 8 replicates, and the treatments consisted of a 2 3 factorial arrangement of egg weight (light and heavy) and three types of the pre-starter feed. The pre-starter diets used were: micro-pelleted diet, with 2900 kcal/kg and low levels of protein and amino acids (P); mash diet, with the same composition (M1); and mash diet, with 2950 kcal/kg and high protein. This feed was provided at a fixed amount of 200 g per chick and, after that, the birds in all treatments were fed a common starter diet in mash form, until 14 days of age. Live weight, weight gain, feed intake and feed conversion were evaluated on a pen basis. The time required for total consumption of the pre-starter feeds was monitored. In both experiments, the albumen was heavier than the other components. In experiment 1, there was influence of the egg weight only in the first week (P<0,05). At seven days, P diet improved the live weight, weight gain and feed conversion (P<0,05). At 14 days, P diet also improved feed conversion, as well the live weight of chicks from heavy eggs. In the same experiment, heavy chicks consumed 200 g of P diet faster than light chicks. In the experiment 2, the time of intake was not different among treatments (P>0,05). There was not influence of egg weight, but there was influence of P and F2 diets in the first week, that improved the feed conversion. However, this influence did not remain to 14 days (P>0,05). It was concluded that albumen is the heaviest component of egg, inside the same age of breeders. It was also concluded that the chicks from breeders of 42 weeks of age were more influenced by different pre-starter diet composition and egg weight than the chicks from breeders of 60 weeks of age. Although P diet showed lower nutritional level, it improved the performance of chicks from breeders of 42 weeks of age.

No description available.

The effect of stage of lactation on milk yield, somatic cell counts, mineral and fatty acid profiles in pasture-based Friesian, Jersey and Friesian × Jersey cows was investigated. Twenty Friesian, twenty Jersey and twenty Friesian × Jersey cows were randomly selected from a dairy herd. A total of 202 milk samples were collected and analysed in three stages of lactation. Genotypic differences were observed in milk yield and fat content. Friesian cows produced the highest yield and lowest fat content whereas the opposite was true for Jersey cows (P<0.01). No significant differences were observed in SCC in the different genotypes, but SCC levels were higher in mid and late lactation (P<0.001). There was no effect (P<0.005) of genotype and stage of lactation interaction on Ca, P, Mg, Na, Mn and Bo concentration. Jersey cows had the least concentration of Fe and Cu in all stages of lactation. Strong positive correlations were observed among Ca and P, Mg and Zn. Aluminium had a strong positive relationship with Bo, Fe, Mn and Zn (P<0.001). Generally, SCC had a weak positive relationship with macro elements but a significant negative relationship with microelements. Yield levels were negatively correlated with Mg, Na, Al, Mn and SCC. Pasture ALA, SFA, n-3, n-6/n-3 and PUFA/MUFA concentration did not differ across the study period. Linoleic acid was highest in the second phase which coincides with mid lactation in cows (P<0.001). Highest moisture content coincided with the least fat free dry matter content in early lactation (P<0.001). Significantly high fat content was observed in late lactation than in early lactation. Highest butyric, caproic, linoleic, n-6 and PUFA were observed for Friesian cows. All other fatty acids ratios were not significantly different among different genotypes. Highest CLA, ALA, LA, SFA, PUFA, n-6, and n-3 and atherogenicity index were observed in early lactation whereas desaturase activity indices were highest in late lactation. Strong positive correlations were observed among milk vaccenic, ALA, LA and CLA concentrations. Inverse relationships were observed between SFA and long chain fatty acids. It can be concluded, it may be of advantage to consume milk from early stage of lactation poses a lower risk to coronary diseases and are much safer to consume.

Feeds often contain molybdenum (Mo) and sulfur (S) in excess of recommended allowances for adequate copper (Cu) absorption by ruminant livestock. Two randomized-block experiments were conducted using lambs given a cereal-based diet (90% of dry matter (DM) intake), containing 8 mg Cu, 0.7 mg Mo and 2.1g S per kg DM, that was either unsupplemented or supplemented with ammonium molybdate or sodium sulfate alone or in combination, to determine the effects of Mo, S and Mo+S on growth, hematology, serum Cu and Mo concentrations and reproductive function. Short term intake (4 weeks) by rams, aged 18 and 20 weeks, of 26 mg Mo alone or in combination with 2g S per kg DM, had no effect on growth, hematology or the concentration of total Cu in serum (TCu). However, supplemented groups had lower (P<0.05) concentrations of serum Cu soluble in trichloroacetic acid (TCA-Cu), but the group given Mo+S had the highest (P<0.05) concentration of serum residual Cu (RCu). Luteinizing hormone (LH) peak amplitude was affected by age*diet interaction (P<0.05), because of high amplitude LH peaks in the serum of lambs, aged 24 wks, given Mo alone. Testosterone serum secretory profiles did not differ among diet groups, but testosterone peak frequency was higher (P<0.05) for older ram lambs. Long term intake (32-39 wks) by ewe, ram and wether lambs (gonadal influence) of 12 mg Mo, or 2g S alone or combined per kg DM also had no effect on hematology or TCu. Food intake and liver weights were higher (P<0.05), but TCA-Cu was lower (P<0.05) for groups given S. Serum concentrations of total Mo (TMo) were higher (P<0.05) for Mo-supplemented groups, but RCu was highest only for the Mo+S group. Growth was affected by Mo*S*gonadal influence*time interaction (P<0.05); until autumn, the body weight of Mo-supplemented groups were higher than those of ram and wether lambs given Mo+S. Ovarian or testicular functions were delayed more severely for Mo- than Mo+S-supplemented groups. Mean concentrations of LH were affected by Mo*S*gonadal influence*time interaction (P<0.05); the mean LH values of Mo-supplemented ram and ewe lambs were higher than the Mo+S-supplemented group, whereas a reverse trend was observed for wether lambs. The amplitude of LH peaks was affected by Mo*S*gonadal influence*time interaction (P<0.05); for ram lambs, LH peak amplitude was higher for Mo than Mo+S-supplemented groups, whereas for wether and ewe lambs the reverse trend was noted. Mean concentrations of serum Cortisol and Cortisol peak amplitude were affected by Mo*S interaction (P<0.05); the mean Cortisol concentration and peak amplitude for the Mo-supplemented group were higher than those for the Mo+S-supplemented group. The frequency of LH and Cortisol peaks did not differ (P>0.10) among diet groups. In conclusion, Mo supplementation of cereal-based diets containing a high concentration of Cu did not adversely affect lamb growth. However, the effect of high dietary Mo on reproductive function appears to depend on the dietary level of S and the induction of high serum RCu (thiomolybdate). Further investigations on the effects of Mo and thiomolybdate on endocrine function may provide a nutritional basis for improving reproductive efficiency in ruminants. / Land and Food Systems, Faculty of / Graduate

No abstract provided / Dissertation (MSc (Agric) Nutrition)--University of Pretoria, 2005. / Animal and Wildlife Sciences / unrestricted

The aim of this study was to evaluate the effect of glycosylation on exogenous xylanase stability when incubated under proteolytic conditions. Xylanase produced by Trichoderma longibrachiatum, was purified using gel filtration chromatography, ammonium sulfate salt precipitation and dialysis. A partially purified xylanase with Mr of 20- and 10 kDa was identified and contained >65% of the original xylanase activity. Glycoproteins present in the xylanase were identified by thymol sulfuric acid staining or by the FITC-Iabeled lectin method, specific for glycoproteins. This naturally glycosylated xylanase was enzymatically deglycosylated with one of two endo-N-glycosidases: PNGase F or Endo H. Efficiency of deglycosylation was determined with electrophoresis by observing protein mobility shifts or by staining with FITC-Iabeled lectin. The effect of glycosylation on the stability of the exogenous xylanase was tested by incubating the glycosylated or deglycosylated xylanase with rumen fluid (Rf), Prevotella ruminicola culture supernatant (Pr) or a commercial protease from Bacillus subtilis (Bs) for 0, 3, 6, 9 and 24h at 37°C. Results indicated that glycosylated xylanase was significantly more stable (P<0.05) against proteolytic inactivation under the relatively low protease conditions of Rf and Pr (0.018 and 0.046 mg azocasein degraded/ml/h, respectively), but not under high proteolytic conditions of Bs (1.009 mg azocasein/mllh). Also, the glycosylation effect was observed earlier when incubated with the numerous proteases of Rf (3h), than with Pr (9h). These results indicate that glycosylation enhances xylanase stability and therefore is an important characteristic for exogenous enzyme supplements for ruminants. / Dissertation (MSc (Agric))--University of Pretoria, 2005. / Animal and Wildlife Sciences / unrestricted