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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

The effect of leguminous browse supplementation on maize husk utilization by goats indigenous to the eastern province of Zambia /

Phiri, Donald Mwelwa January 1991 (has links)
Small maize livestock farmers in the Eastern Province of Zambia badly need forage high in protein to supplement the protein deficient pasture grass. Nutrient intake, especially for the small ruminants with small gastro-intestinal capacity compared to metabolizable energy requirement, will be near or below maintenance if these poor quality feeds are not supplemented. High quality supplements however, are beyond the reach of the small scale farmers. The effect of feeding maize husk and leucaena as a mixture or separately on voluntary intake of maize husk was studied over a 40 day period. Ten male goats with an average weight of 15 kg were used. In a separate experiment the effect of browse supplementation on maize husk utilization by goats was studied. The treatments were; maize husk plus urea; maize husk plus Leucaena leucocephala (3:2); maize husk plus Calliandra calothyrsus (3:2); and maize husk plus leucaena plus calliandra (3:1:1). The results of the study indicate that leucaena and calliandra are both potentially valuable feed components.
12

Feed digestion of growing Saanen goats /

Leite, Rafael Fernandes. January 2015 (has links)
Orientador: Izabelle Auxiliadora Molina de Almeida Teixeira / Banca: Gustavo Rezende Siqueira / Banca: Antonello Cannas / Banca: Gilberto de Lima Macedo Junior / Banca: Renata Helena Branco Arnandes / Resumo: O objetivo principal foi determinar a contribuição dos diferentes segmentos do trato gastrointestinal (TGI) para a digestão da fibra. Dois experimentos foram conduzidos, os quais foram determinados o tempo médio de retenção (TMR) de partículas e líquido, conteúdo e pesos dos tecidos nos diferentes segmentos pelo método do abate. O primeiro estudo avaliou TMR de partículas e líquido de cabritos Saanen em crescimento de diferentes sexos e submetidos a diferentes níveis de restrição alimentar. Foram utilizados 54 cabritos da raça Saanen (18 fêmeas, 18 machos castrados e 18 machos inteiros) em um arranjo fatorial 3 × 3 que compreendeu os três sexos e três níveis de restrição alimentar (ad libitum / sem restrição, restrição moderada e severa). Contrastes polinomiais foram utilizados para determinar o efeito linear e quadrático da restrição alimentar, enquanto o efeito do sexo foi comparado pelo teste de Tukey. Os efeitos do sexo e interação entre sexo e restrição alimentar não foram significativos na maioria das variáveis avaliadas. A restrição alimentar aumentou o TMR de partículas e fluído. O TMR foi um recurso importante para aumentar a oferta de nutrientes, quando os animais foram submetidos à restrição alimentar, como indicado pelo aumento da digestibilidade total. O segundo estudo avaliou aspectos fisiológicos da digestão da fibra, retenção de partículas e líquido, conteúdo e peso dos tecidos em todo o TGI de cabritos da raça Saanen. O total de 58 cabritos da raça Saanen foram aleatoriamente dispostos em um arranjo fatorial 3 × 3, composto por três sexos (fêmeas, machos castrados, machos inteiros) e três pesos de abate (aproximadamente 16, 23, e 30 kg de peso no abate). Os efeitos do tratamento foram avaliados em um esquema de parcelas subdivididas, com o sexo como efeito principal e peso de abate como sub parcela. Contrastes polinomiais foram utilizados para determinar os efeitos ... / Abstract: The main objective was to assess the contribution of different segments of the gastrointestinal tract (GIT) to the fiber digestion. Two experiments were conducted, which mean retention time (MRT) of particulate and liquid matter, pool size, and tissues weight in different segments were determined by slaughter technique. The study one evaluated MRT of particulate and liquid matter in growing Saanen goats of different sexes and subjected to different levels of feed restriction. Fifty-four Saanen goats (18 each of females, castrated males and intact males) were used in a 3×3 factorial arrangement comprising the three sexes and three levels of feed restriction (unrestricted/ad libitum, moderate and severe restriction). Polynomial contrasts were used to determine linear and quadratic effect of feed restriction, while the effect of sex was compared by Tukey test. The effects of sex and the interaction between sex and feed restriction were not significant on most of variables evaluated. In conclusion, the level of feed restriction increased the MRT of particulate and liquid matter. The MRT was an important mechanism to increase nutrient supply when animals were subjected to feed restriction, as indicated by increased total tract digestibility. The second study examined physiological aspects in the digestion of fiber, particulate and liquid matter residence, pool size, and tissues weight in the whole tract of growing Saanen goats. A total of 58 Saanen goats were disposed in a 3×3 factorial arrangement consisting of three sexes (female, castrated males, intact males) and three slaughter weights (target BW 16, 23, and 30 kg at slaughter). Treatment effects were evaluated in a split-plot design, with sex as the main plot and slaughter weight as the subplot. Polynomial contrasts were used to determine linear and quadratic effects of slaughter weight. Thus increased BW at slaughter resulted in greater MRT of particulate and liquid matter in ... / Doutor
13

Efeitos do sistema de alimentação e grupo racial no desempenho, características de carcaça e qualidade da carne de cabritos confinados

Souza, Pedro Paulo Sobolow de [UNESP] 12 November 2012 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:33:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-11-12Bitstream added on 2014-06-13T20:05:47Z : No. of bitstreams: 1 souza_pps_dr_botfmvz.pdf: 531123 bytes, checksum: 13de4f067ef997c14711de62dfacffde (MD5) / Universidade Estadual Paulista (UNESP) / O experimento foi realizado com o objetivo de avaliar efeitos do sistema de alimentação e grupo racial no desempenho, medidas biométricas e análise morfológica do estômago de cabritos confinados. Foi utilizado o delineamento em blocos (gênero) casualizado em esquema fatorial 5 x 2, sendo os grupos raciais: A (Alpino), AN (Anglo-Nubiano), 1/2 BA (1/2 Boer + 1/2 Alpino), 3/4 BA (3/4 Boer + 1/4 Alpino) e 7/8 BA (7/8 Boer + 1/8 Alpino), e os sistemas de alimentação: dieta experimental sem leite e dieta experimental mais 1,5 L de leite/animal/dia. Os animais foram abatidos após atingirem 30 kg de peso vivo. Como o melhor desempenho foi obtido com animais 1/2 BA, não há necessidade de o produtor manter fêmeas mestiças 1/2 BA e 3/4 BA no rebanho. A utilização de leite excedente pode ser recomendada, uma vez que não trouxe prejuízos ao desempenho e medidas biométricas dos animais, ajudou a reduzir o peso total do estômago, além de uma economia de 51,39 % no consumo da dieta / The experiment was conducted to evaluate effects of feeding system and racial group in the performance, biometric measurements and morphological analysis of the stomach of confined goats. It was used a block design (gender) randomized in a factorial scheme 5 x 2, being the racial groups: A (Alpine), AN (Anglo-Nubian), 1/2 BA (1/2 Boer + 1/2 Alpine), 3/4 BA (3/4 Boer + 1/4 Alpine) and 7/8 BA (7/8 Boer + 1/8 Alpine), and the feeding systems: experimental diet without milk and experimental diet more 1.5 L of milk/animal/day. The animals were slaughtered after reaching 30 kg of live weight. As the best performance was obtained with the 1/2 BA, no have need the producer keep crossbred females 1/2 BA and 3/4 BA in the herd. The use of surplus milk can be recommended, since it did not caused damage to the biometric measurements and performance of the animals, helped reduce the total weight of the stomach, besides an economy of 51,39 % in the diet consumption
14

Feed digestion of growing Saanen goats

Leite, Rafael Fernandes [UNESP] 27 January 2015 (has links) (PDF)
Made available in DSpace on 2015-06-17T19:34:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-01-27. Added 1 bitstream(s) on 2015-06-18T12:47:00Z : No. of bitstreams: 1 000832495.pdf: 500908 bytes, checksum: d28d71caf64194fbb19d1187888295ae (MD5) / O objetivo principal foi determinar a contribuição dos diferentes segmentos do trato gastrointestinal (TGI) para a digestão da fibra. Dois experimentos foram conduzidos, os quais foram determinados o tempo médio de retenção (TMR) de partículas e líquido, conteúdo e pesos dos tecidos nos diferentes segmentos pelo método do abate. O primeiro estudo avaliou TMR de partículas e líquido de cabritos Saanen em crescimento de diferentes sexos e submetidos a diferentes níveis de restrição alimentar. Foram utilizados 54 cabritos da raça Saanen (18 fêmeas, 18 machos castrados e 18 machos inteiros) em um arranjo fatorial 3 × 3 que compreendeu os três sexos e três níveis de restrição alimentar (ad libitum / sem restrição, restrição moderada e severa). Contrastes polinomiais foram utilizados para determinar o efeito linear e quadrático da restrição alimentar, enquanto o efeito do sexo foi comparado pelo teste de Tukey. Os efeitos do sexo e interação entre sexo e restrição alimentar não foram significativos na maioria das variáveis avaliadas. A restrição alimentar aumentou o TMR de partículas e fluído. O TMR foi um recurso importante para aumentar a oferta de nutrientes, quando os animais foram submetidos à restrição alimentar, como indicado pelo aumento da digestibilidade total. O segundo estudo avaliou aspectos fisiológicos da digestão da fibra, retenção de partículas e líquido, conteúdo e peso dos tecidos em todo o TGI de cabritos da raça Saanen. O total de 58 cabritos da raça Saanen foram aleatoriamente dispostos em um arranjo fatorial 3 × 3, composto por três sexos (fêmeas, machos castrados, machos inteiros) e três pesos de abate (aproximadamente 16, 23, e 30 kg de peso no abate). Os efeitos do tratamento foram avaliados em um esquema de parcelas subdivididas, com o sexo como efeito principal e peso de abate como sub parcela. Contrastes polinomiais foram utilizados para determinar os efeitos ... / The main objective was to assess the contribution of different segments of the gastrointestinal tract (GIT) to the fiber digestion. Two experiments were conducted, which mean retention time (MRT) of particulate and liquid matter, pool size, and tissues weight in different segments were determined by slaughter technique. The study one evaluated MRT of particulate and liquid matter in growing Saanen goats of different sexes and subjected to different levels of feed restriction. Fifty-four Saanen goats (18 each of females, castrated males and intact males) were used in a 3×3 factorial arrangement comprising the three sexes and three levels of feed restriction (unrestricted/ad libitum, moderate and severe restriction). Polynomial contrasts were used to determine linear and quadratic effect of feed restriction, while the effect of sex was compared by Tukey test. The effects of sex and the interaction between sex and feed restriction were not significant on most of variables evaluated. In conclusion, the level of feed restriction increased the MRT of particulate and liquid matter. The MRT was an important mechanism to increase nutrient supply when animals were subjected to feed restriction, as indicated by increased total tract digestibility. The second study examined physiological aspects in the digestion of fiber, particulate and liquid matter residence, pool size, and tissues weight in the whole tract of growing Saanen goats. A total of 58 Saanen goats were disposed in a 3×3 factorial arrangement consisting of three sexes (female, castrated males, intact males) and three slaughter weights (target BW 16, 23, and 30 kg at slaughter). Treatment effects were evaluated in a split-plot design, with sex as the main plot and slaughter weight as the subplot. Polynomial contrasts were used to determine linear and quadratic effects of slaughter weight. Thus increased BW at slaughter resulted in greater MRT of particulate and liquid matter in ...
15

Abacate (Persea americana Mill.) na alimentação de cabras: produção, composição e perfil de ácidos graxos no leite e parâmetros ruminais / Production, composition and profile of milk fatty acids in anglo nubian lactanting goats receiving pulp and avocado oil (Persea americana Mill.) on the diet

Pastor López, Francisco Javier [UNESP] 06 July 2015 (has links) (PDF)
Made available in DSpace on 2015-08-20T17:10:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-07-06. Added 1 bitstream(s) on 2015-08-20T17:25:35Z : No. of bitstreams: 1 000844494.pdf: 950401 bytes, checksum: 3c8c3567770f69b3eab85141a009262a (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A estratégia mais rápida para alterar o perfil de ácidos graxos do leite de maneira a beneficiar a saúde do consumidor é aumentar o teor do ácido linoléico conjugado (CLA) por meio da suplementação da dieta dos animais com óleos vegetais. Este trabalho objetivou avaliar a inclusão de abacate na dieta de cabras, por meio da polpa da fruta com 16% de extrato etéreo (EE) na matéria seca (MS) e óleo comercial com 8% de EE na MS sobre: consumo, produção, composição e perfil de ácidos graxos do leite. Foram usadas seis cabras Anglo-nubianas em lactação, distribuídas em dois quadrados latinos 3 x 3 balanceados. A dieta com polpa reduziu e a de óleo aumentou o consumo de MS em relação ao controle (3% EE na MS), sendo observada a mesma tendência para os nutrientes, exceção para o EE que foi mais consumido na dieta com polpa em relação ao controle. Os teores de sólidos totais e gordura do leite foram maiores na dieta com óleo em relação ao controle, e estes não diferirem da polpa, os demais constituintes e a produção de leite não foram influenciados pelas dietas. Observou-se redução no teor de ácidos graxos de cadeia curta no leite das cabras suplementadas com fontes lipídicas em relação ao controle, e aumento no nível de CLA em 56,88 e 66,10% nas dietas com polpa e óleo respectivamente. A suplementação de ácidos graxos insaturados por meio do óleo ou da polpa de abacate aumenta a concentração de CLA e diminui os ácidos graxos de cadeia curta, melhorando assim as propriedades nutracêuticas do leite podendo beneficiar a saúde dos consumidores / The fastest strategy that alters Milk fatty acid profile in order to benefit consumer health is to improve the level of conjugated linoleic acid (CLA) by supplementing animal diets with vegetable oils. This research aimed to evaluate goat diets supplemented with avocado addition using a fruit polp with 16% of ether extract (EE) in dry matter (DM) and commercial oil with 8% EE in DM on: intake and milk production, chemical composition and fatty acid profile. There were used six Anglo Nubian lactating goats, distributed in two balanced 3 x 3 latin squares. Pulp diet reduced and oil diet improved DM intake in relation to control (3% EE), and the nutrients followed the same tendency, except for EE, that was more consumed in pulp and oil diets. The content of milk total solids and fat were higher in oil diet in relation to control, and did not differ from pulp diet, the other constituents and the milk production were not influenced by diets. In relation to fatty acids, it was observed reduction in short chain fatty acids in milk from goats supplemented with lipid sources in relation to control and increase on CLA level in 56,88 and 66,10/% in treatments with pulp and oil respectively. The supplementation with unsaturated fatty acids by avocado oil and pulp increases CLA concentration and decreases short chain fatty acids, improving milk nutraceutical properties, what can benefit consumer health. / FAPESP: 13/07146-0
16

Abacate (Persea americana Mill.) na alimentação de cabras: produção, composição e perfil de ácidos graxos no leite e parâmetros ruminais /

Pastor López, Francisco Javier, 1975. January 2015 (has links)
Orientador: Heraldo César Gonçalves / Banca: Paulo Roberto de Lima Meirelles / Banca: Simone Fernandes / Banca: Helen Fernanda Barros Gomes / Banca: Gil Ignacio Lara Canizares / Resumo: A estratégia mais rápida para alterar o perfil de ácidos graxos do leite de maneira a beneficiar a saúde do consumidor é aumentar o teor do ácido linoléico conjugado (CLA) por meio da suplementação da dieta dos animais com óleos vegetais. Este trabalho objetivou avaliar a inclusão de abacate na dieta de cabras, por meio da polpa da fruta com 16% de extrato etéreo (EE) na matéria seca (MS) e óleo comercial com 8% de EE na MS sobre: consumo, produção, composição e perfil de ácidos graxos do leite. Foram usadas seis cabras Anglo-nubianas em lactação, distribuídas em dois quadrados latinos 3 x 3 balanceados. A dieta com polpa reduziu e a de óleo aumentou o consumo de MS em relação ao controle (3% EE na MS), sendo observada a mesma tendência para os nutrientes, exceção para o EE que foi mais consumido na dieta com polpa em relação ao controle. Os teores de sólidos totais e gordura do leite foram maiores na dieta com óleo em relação ao controle, e estes não diferirem da polpa, os demais constituintes e a produção de leite não foram influenciados pelas dietas. Observou-se redução no teor de ácidos graxos de cadeia curta no leite das cabras suplementadas com fontes lipídicas em relação ao controle, e aumento no nível de CLA em 56,88 e 66,10% nas dietas com polpa e óleo respectivamente. A suplementação de ácidos graxos insaturados por meio do óleo ou da polpa de abacate aumenta a concentração de CLA e diminui os ácidos graxos de cadeia curta, melhorando assim as propriedades nutracêuticas do leite podendo beneficiar a saúde dos consumidores / Abstract: The fastest strategy that alters Milk fatty acid profile in order to benefit consumer health is to improve the level of conjugated linoleic acid (CLA) by supplementing animal diets with vegetable oils. This research aimed to evaluate goat diets supplemented with avocado addition using a fruit polp with 16% of ether extract (EE) in dry matter (DM) and commercial oil with 8% EE in DM on: intake and milk production, chemical composition and fatty acid profile. There were used six Anglo Nubian lactating goats, distributed in two balanced 3 x 3 latin squares. Pulp diet reduced and oil diet improved DM intake in relation to control (3% EE), and the nutrients followed the same tendency, except for EE, that was more consumed in pulp and oil diets. The content of milk total solids and fat were higher in oil diet in relation to control, and did not differ from pulp diet, the other constituents and the milk production were not influenced by diets. In relation to fatty acids, it was observed reduction in short chain fatty acids in milk from goats supplemented with lipid sources in relation to control and increase on CLA level in 56,88 and 66,10/% in treatments with pulp and oil respectively. The supplementation with unsaturated fatty acids by avocado oil and pulp increases CLA concentration and decreases short chain fatty acids, improving milk nutraceutical properties, what can benefit consumer health. / Doutor
17

Efeitos do sistema de alimentação e grupo racial no desempenho, características de carcaça e qualidade da carne de cabritos confinados /

Souza, Pedro Paulo Sobolow de, 1956- January 2012 (has links)
Orientador: Heraldo Cesar Gonçalves / Banca: Roberto de Oliveira Roça / Banca: Cyntia Ludovico Martins / Banca: Sirlei Aparecida Maestá / Banca: Helen Fernanda Barros Gomes / Resumo: O experimento foi realizado com o objetivo de avaliar efeitos do sistema de alimentação e grupo racial no desempenho, medidas biométricas e análise morfológica do estômago de cabritos confinados. Foi utilizado o delineamento em blocos (gênero) casualizado em esquema fatorial 5 x 2, sendo os grupos raciais: A (Alpino), AN (Anglo-Nubiano), 1/2 BA (1/2 Boer + 1/2 Alpino), 3/4 BA (3/4 Boer + 1/4 Alpino) e 7/8 BA (7/8 Boer + 1/8 Alpino), e os sistemas de alimentação: dieta experimental sem leite e dieta experimental mais 1,5 L de leite/animal/dia. Os animais foram abatidos após atingirem 30 kg de peso vivo. Como o melhor desempenho foi obtido com animais 1/2 BA, não há necessidade de o produtor manter fêmeas mestiças 1/2 BA e 3/4 BA no rebanho. A utilização de leite excedente pode ser recomendada, uma vez que não trouxe prejuízos ao desempenho e medidas biométricas dos animais, ajudou a reduzir o peso total do estômago, além de uma economia de 51,39 % no consumo da dieta / Abstract : The experiment was conducted to evaluate effects of feeding system and racial group in the performance, biometric measurements and morphological analysis of the stomach of confined goats. It was used a block design (gender) randomized in a factorial scheme 5 x 2, being the racial groups: A (Alpine), AN (Anglo-Nubian), 1/2 BA (1/2 Boer + 1/2 Alpine), 3/4 BA (3/4 Boer + 1/4 Alpine) and 7/8 BA (7/8 Boer + 1/8 Alpine), and the feeding systems: experimental diet without milk and experimental diet more 1.5 L of milk/animal/day. The animals were slaughtered after reaching 30 kg of live weight. As the best performance was obtained with the 1/2 BA, no have need the producer keep crossbred females 1/2 BA and 3/4 BA in the herd. The use of surplus milk can be recommended, since it did not caused damage to the biometric measurements and performance of the animals, helped reduce the total weight of the stomach, besides an economy of 51,39 % in the diet consumption / Doutor
18

The effects of goat browsing on ecosystem patterns and processes in succulent thicket, South Africa

Lechmere-Oertel, Richard Geoffrey January 2003 (has links)
Transformation in the arid succulent thicket of the Eastern Cape of South Africa in response to unsustainable livestock production has been widespread, with less than 10 percent remaining intact. Transformation in succulent thicket has resulted in large areas of dense thicket (comprising a two-phase mosaic of perennial-vegetated patches separated by animal paths and bare patches) being replaced with a ‘pseudo-savanna’ of remnant canopy trees with a structurally simple field layer of ephemeral and short- lived perennial grasses and forbs. There is an extensive literature describing the transformation of succulent thicket, with many speculative statements about the underlying mechanisms of transformation. The central focus of this study was to improve our mechanistic understanding of transformation in succulent thicket using field experiments. Hopefully these results will set another foundation upon which future management of succulent thicket can be improved and large-scale restoration initiated. This study comprises four themes that are linked to the concept of landscape function. The central premise of landscape function is that functional landscapes have mechanisms that capture and retain scarce resources. Conversely, as landscapes become increasingly dysfunctional, so these mechanisms become disrupted. In succulent thicket, dysfunctio n appears to be linked to the reduced ability to harvest water, cycle carbon and a loss of organic carbon. In this thesis I examined some of the key processes that influence water and organic carbon fluxes: perennial vegetation cover, soil fertility, litter fall and decomposition, and runoff and soil erosion. The experimental design that was used for all this work was a factorial ANOVA based on replicated fenceline contrasts that reflect differences in long-term management history. The main objectives of this thesis were to: quantify the patterns of transformation in an arid form of succulent thicket, including changes in the biomass, cover and structure of the dominant vegetation guilds; test the stability of the transformed succulent thicket ecosystem to show whether it is a new stable state or an intermediate stage in a trajectory towards a highly desertified state where only the ephemeral grasses and forbs persist; describe and compare soil fertility across transformation contrasts, concentrating on changes in the spatial patterns of soil resources and the ability of the soil to harvest precipitation; to compare litter fall and decomposition of leaf material from the dominant plants in intact and transformed succulent thicket; to quantify and compare run-off and erosion from run-off plots in intact and transformed succulent thicket. Transformation and stability I quantified the changes in plant diversity, physiognomy and biomass that occur across transformation contrasts. Thicket transformation results in a significant loss of plant diversity and functional types. There is also a significant reduction in the biomass (c. 80 t.ha-1) and structural complexity of the vegetation, both vertically and horizontally. These results were interpreted in terms of their implications for ecosystem functioning and stability. To test the stability of the transformed succulent thicket I used aerial photographs and ground-truthing to track the survivorship of canopy trees over 60 years in pseudo-savanna landscapes. I also measured seedling establishment in different habitats. I show that the pseudo-savanna is not a stable state owing to ongoing adult mortality and no recruitment of canopy trees. Soil fertility and water status I hypothesised that the above-ground changes in ve getation would be accompanied by similar trends in the pattern and levels of soil nutrient resources and the ability of the landscape to harvest precipitation. I compared soil fertility (organic carbon, available nitrogen and phosphorus), texture, matric potential, and surface micro-topography in the two main micro- habitats on either side of the replicated fenceline contrasts. The results show that intact spekboom thicket has a distinct spatial pattern of soil fertility where nutrients and organic carbon are concentrated under the patches of perennial shrubs, compared to under canopy trees and open spaces. Transformation results in a significant homogenisation out of this pattern and an overall reduction in the fertility of the landscape. The proportion of the landscape surface that would promote infiltration of water decreases from 60 – 0.6 percent. Soil moisture retention (matric potential) also decreases with transformation. I interpreted these patterns in terms of the ability of the landscape to harvest and release water after rainfall events. Litter fall and decomposition Surface litter and soil organic matter are critical components to wooded ecosystems; contributing to several ecosystem functions. The rates of litter fall and decomposition are ratelimiting steps in nutrient cycling and incorporation of organic matter into the soil. The ecological mechanisms behind the collapse of succulent thicket in the face of domestic herbivory are not fully understood, but are believed to include the breakdown of several ecosystem processes, including litter fall and decomposition. I quantified the changes in litter fall and litter decomposition of four of the dominant perennial woody plants (Euclea undulata, Pappea capensis, Portulacaria afra and Rhus longispina) across the replicated fenceline. Litter fall was measured over 14 months using mesh traps. Decomposition was measured over 15 months using a combination of litterbags and unprotected leaf packs. I also quantified soil microclimate during the experimental period; hypothesising that transformation would lead to soil conditions less amenable for biotic activity. Litter fall in succulent thicket was very high for a semi-arid system, comparing more to temperate forests. The leaf-succulent P. afra contributed the largest single component of the total litter production at a landscape scale. The effect of transformation on litter fall was species specific. Deep-rooted or drought-adapted species showed no change in litter yield with transformation; shallow-rooted species showed a significant decrease. There were few significant differences in decomposition rates across the transformation gradient and between litter types. Portulacaria afra litter had the steepest rate of mass loss, and was most affected by transformation. The more recalcitrant (high C:N ratio) leaves of P. capensis remained largely unaffected by transformation. These results indicate the critical role of the perennial vegetation in incorporating organic carbon into the soil. Transformation of succulent thicket leads to a disruption of the flow of carbon into the soil, reinforcing the cycle of transformation through reduced fertility. Rehabilitation of this ecosystem will require the active establishment of species, such as P. afra, that will restart the flow of carbon into the soil. Run-off & Erosion The landscape function model predicts that functional semi-arid shrublands efficiently conserve limiting resources such as water and water-bourn sediments (soil and organic matter). As these rangelands become transformed through unsustainable livestock production, so their ability to conserve resources decreases. The primary determinant of landscape function and conservation of resources appears to be the proportional cover of perennial vegetation. I hypothesised that the switch from a two-phase mosaic dominated by perennial succulent and woody shrubs to a single phase system dominated by an ephemeral field layer would be accompanied by disruption of the mechanisms that conserve resources. Specifically, I tested the hypothesis that transformation of succulent thicket increases runoff volume, sediment concentration of runoff, soil erosion and loss of organic matter at a patch scale (c. 100 m2). Runoff and water-borne sediment were measured from runoff plots established across replicated fenceline contrasts. Data were collected from eight extreme weather events over two years. There were no significant differences between runoff and erosion across the transformation contrast, as each extreme weather event was unique in terms of its runoff response. The transformed runoff plots alone also gave inconsistent results, largely due to differences in the cover of ephemeral forbs and weakly perennial grasses. Runoff and erosion were not predictable from the data across the transformation gradient due to complex interactions between the nature of the above-ground vegetation, soil micro-topography and land use history. The results highlighted the need for longer-term catchment experiments to generate a predictive understanding of the effect of transformation on runoff and erosion in succulent thicket.
19

Effects of dietary supplementation on physico-chemical and consumer sensory characteristics of chevon from South African indigenous goat genotypes

Xazela, Nomasonto Martha January 2010 (has links)
The study was conducted at the University of Fort Hare farm to assess the effect of dietary supplementation on physico-chemical and consumer sensory characteristics of chevon from South African indigenous goat genotypes. Forty-eight 6-month-old Xhosa lop-eared (XLE), Nguni (NGN), Xhosa-Boer cross (XBC) and Boer (BOR) castrated goats with a body weight range from 20 to 25 kg were used in this study. Half of the goats in each genotype were supplemented with 200g/head/day of sunflower cake. The other half of goats in each genotype was not supplemented. The goats were slaughtered at day 90 to determine slaughter weight (SLW), cold dress mass (CDM), meat colour, cooking loss, meat pH and Warner-Bratzler (WB) shear force values. Furthermore, a consumer sensory evaluation of cooked or fried chevon from supplemented and non-supplemented goats was conducted with consumers of different ages, tribes and gender. The XLE and NGN goats had higher pH24 (P < 0.05) than BOR and XBC goats. Supplemented BOR goats had higher L* values than their non-supplemented counterparts (P < 0.05). The other meat quality attributes in XLE and NGN were comparable to those in meat from the Boer goat. Female respondents gave higher (P < 0.05) sensory scores than male respondents for both cooked and fried meat on aroma intensity. Shona consumers gave higher (P < 0.05) aroma intensity scores than the Xhosa and the Zulu consumers for both cooked and fried meat. In the non-supplemented goats, fried meat for all genotypes was superior (P < 0.05) to the cooked meat for initial impression of juiciness. Age and gender of respondents and thermal iv treatment influenced initial impression of juiciness scores (P < 0.05). The quality of chevon from XLE and NGN was comparable to that of the Boer goat, and dietary supplementation improved most meat quality attributes. Chevon from the supplemented goats had higher consumer sensory scores than chevon from the non-supplemented goats. Keywords: supplementation, meat colour, ultimate pH, consumer sensory evaluation, Xhosa lop eared, Nguni, Boer goats.
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Feeding behaviour of Xhosa lop-eared, Nguni and Nguni x Boer goat genotypes kept on rangelands of the false thornveld

Bakare, Archibold Garikayi January 2009 (has links)
Feeding behaviour of Xhosa lop-eared, Nguni and Nguni × Boer goat genotypes kept on rangelands of the False Thornveld By Archibold Garikayi Bakare The study was conducted at the University of Fort Hare farm to assess the feeding behaviour of three goat genotypes: Xhosa lop-eared (XLE), Nguni (NGN) and Nguni × Boer crossbred (NBC) genotypes. The time spent on different activities (grazing, browsing and other activities) on rangelands was recorded using stop watches. The micro-histological faecal analysis technique was used to identify and quantify the plant species that were consumed by the goats across the four seasons. Time spent browsing was high in post-rainy season for XLE (55.94 %) compared to NGN (52.97 %) and crossbred NBC (45.95 %) goats. The high browsing activity was also noted for XLE in hot-wet and cool-dry season (P < 0.05). The NBC goats on the other hand; devoted most of their time grazing compared to XLE and NGN goats across seasons (P < 0.05). Generally, time of day had no effect (P > 0.05) on foraging activities among the goat breeds. Grewia occidentalis, Panicum maximum and Diospyros lycioides were the most preferred plant species by all genotypes across seasons in the paddock. It was concluded that crossbreds spent more time grazing as compared to XLE, which are more of browsers. It could, therefore, be recommended that XLE complement with grazers (cattle and sheep) for efficient management of feed resources in rangelands.

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