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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

Feeding behaviour, diet selection of goats and nutritive value of browse species in sub-humid subtropical savannah, South Africa.

Basha, Nasreldin Abdelrahim Dafaalla. January 2012 (has links)
Diet selection and its variation due to difference in forages nutritive value are central processes in plant-herbivore interactions. An incorporating of these parameters may allow predicting diet selection patterns which are a basic underpin for sustainable vegetation management and profitable animal production. To achieve these issues many studies were done two of which were run to study the browse-browser interactions in a sub-humid subtropical savannah, a herd of goats was used as a model browser in natural pasture. Other studies evaluated the nutritive value of five plant species which were the most selected by goats. The objectives of this study were to (i) determine the seasonal patterns of diet selection of goats on woody species and their nutritive value and (ii) to predict the diet selection. The secondary objectivrs were to (i) investigate how plant characteristics such as plant morphology (spinescence, and broad vs. fine leaves), phenology (evergreen vs. deciduous species) and plant chemistry (nitrogen, neutral detergent fibre, acid detergent fibre, acid detergent lignin, condensed tannin, cellulose and hemicellulose) are relate to the diet selection patterns and to (ii) evaluate the nutritive value of the most plant species selected by goats during the different seasons. Two experiments were conducted at Owen Sitole College of Agriculture, KwaZulu-Natal, to determine diet selection of goats grazing/browsing in Zululand Thornveld. The first experiment was done in the early wet season (November 2007) and late wet season (March/April 2008) while the second experiment was conducted in the dry season (June/July 2008), early wet season (November/December 2008) and late wet season (February/March 2009). The relative abundance of browse species in the veld was determined and used to estimate the selection index. In the first part, diet selection was estimated using (i) direct observation of animals (account bouts) by observing every one minute two goats while they were foraging with others for 3 hours in the morning and 1.5 hours in the afternoon on alternate days for a total of six days and (ii) an indirect plant-based method by observing at regular intervals 40 marked branches on ten plants of each browse species every two days for a total of six days. The browse species observed were: Gymnosporia senegalensis, Acacia nilotica, Acacia karroo (Acacia natalitia), Scutia myrtina and Dichrostachys cinerea. In both seasons, the three most selected species according to the plant-based observations were S. myrtina, A. karroo and D. cinerea. Consistently, A. nilotica experienced moderate defoliation and G. senegalensis the least. However, on the basis of the selection index, the species followed the order: A. nilotica > D. cinerea > A. karroo > S. myrtina > G. senegalensis in the early wet season and A. nilotica > S. myrtina > D. cinerea > A. karroo > G. senegalensis in the late wet season. Both methods did not rank species in the same order. The selection index was negatively (P<0.05) correlated to neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL). In the second part, observations were taken on feeding time of two goats, randomly selected per day for 7-8 days. Observations were made during active foraging periods for 2 hrs in the morning and 1.5 hrs in the afternoon. The duration of each feeding bout and the species of woody plant from which bites were cropped at each feeding station were recorded. Season and plant species affected diet selection and preference. The five main species selected (utilized) by goats in decreasing order were S. myrtina, A. nilotica, D. cinerea, Acacia natalitia and Chromolaena odorata. Scutia myrtina was the most preferred (highest utilisation relative to availability) in the dry season while D. cinerea comprised the greatest proportion in the early and late wet seasons. Scutia myrtina was most preferred in the dry and early wet seasons while A. nilotica was most preferred in the late wet season. Spinescent species were generally selected more than non-spinescent species in all seasons, while fine-leaf and deciduous species were selected more than broad-leaf and evergreen ones in the wet seasons. However, preference for broad-leaf and evergreen species increased in the early wet season. Although plant chemistry varied across seasons, it did not explain the preference of goats for various plant species in this study. Instead, effects of chemistry were species- specific. The nutritive value of the five main species selected by goats was evaluated by chemical composition, in vitro gas production, in vitro degradability and in sacco degradability. Two experiments were conducted for the in vitro studies, the first experiment was to test the effect of season and species, while the second experiment tested the biological effect of tannins using polyethylene glycol 4000 (PEG). The PEG treatment was applied to samples of the early and late wet seasons only. The parameters were maximum gas production (GP), degradation rate (C), lag time (lt), maximum rate of GP at the point of inflection (μ), half time to the maximum gas volume(T1/2), gas produced from fermentation of soluble and slowly degradable fractions (A and B, respectively), their degradation rates (c1 and c2, respectively), apparent (ApDeg) and true degradability (TrDeg), microbial yield (MY), partitioning factor (PF), degradation efficiency factor (DEF) and short chain fatty acids (SCFA). There were wide variations among seasons and species in crude protein (CP), NDF, ADF and condensed tannins. Season and species affected kinetics of gas production, GP, TrDeg, MY, PF and SCFA. Chromolaena odorata had the highest CP (185.8-226.4 g kgˉ¹), GP (87.3-104.1 ml gˉ¹ DM), gas produce from soluble (47.6-50.9 ml gˉ¹ DM) and insoluble (39.8-50.9 ml gˉ¹ DM) fractions during the three seasons compared to other browse species. The TrDeg ranged from 634 to 856 g kgˉ¹ DM. The total SCFA varied between seasons and among species. The addition of PEG decreased TrDeg and PF, and increased GP and total SCFA. The GP, its degradation rate (C) and gas from the soluble fraction were positively correlated to CP without and with PEG. Gas from the soluble fraction was negatively correlated to NDF, ADL and CT; and GP to CT without PEG. In the in sacco study, the parameters of dry matter (DM) and nitrogen (N) degradability were soluble (a) and slowly (b) degradable degradability, the degradation rate (c), potential degradable (PD), effective degradability (ED) and lag time (lt). Season affected PD of DM degradability and ED of both DM and CP. Browse species and its interaction with season affected all parameters except b fraction of CP and interaction did not affected PD of CP. Chromolaena odorata had the highest estimated parameters of degradation during the three seasons compared to other browse species. Based on PD and ED, the plant species followed this decreasing order: C. odorata, A. nilotica, A. natalitia, S. myrtina and D. cinerea. All parameters were positively correlated to CP except the a and b fractions of DM and CP, respectively, and lt of both DM and CP. All parameters were negatively correlated to NDF, ADF and ADL except the b fraction and rate of degradation. Condensed tannins (CT) were negatively correlated with all parameters except the b fraction and PD of DM and CP, and lt of DM degradation. Cellulose was negatively correlated with a of DM and lt of CP degradation. The broad objective of this study was to assess whether plant characteristics, in sacco degradability, in vitro gas production, digestibility or chemical composition (NDF, ADF, ADL, CT and CP) could predict the selection of browse species. The parameters were selection index, plant characteristics (spinescence, or leaves phenology), chemical composition, in vitro gas production, in vitro degradability and in sacco degradability parameters. Most of these parameters were poor for predicting selection by goats of browse species. Spinescence (spn), leaves phenology (phen), NDF, CP and CT accounted for 86% of the variation in selection index (y) = -5.91 - 0.01CT - 0.002NDF + 0.02CP + 6.18spn + 2.43phen; (R2=0.86; n=20; RMSE=0.406; P<0.001; for phen, 1 = evergreen, 0 = deciduous; for spn, 1 = spinescent, 0 = spineless). It was concluded that in vitro gas production, in vitro degradability and in sacco degradability were poor predictors of selection index of browse species used by goats. Spinescence, leaf phenology, condensed tannins, CP and NDF were predictors of diet selection index and suggested that these plant species have potential to be used as feed supplements. Chromolaena odorata has the highest potential as feed protein source in goats. The addition of PEG (tannin binding agent) emphasizes that the inhibitory effect of tannins on rumen microbes was great in tannin-rich feeds. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.
12

Diet selection and foraging efficiency of Nguni goats in the bushveld of Gauteng, South Africa.

Werekeh, Fomum Sylvester. 29 November 2013 (has links)
Diet selection and foraging efficiency are primary driving behavioural processes in mammalian herbivore plant interaction. They determine the quality of production and also impact on vegetation, necessitating managerial inputs that will sustain productivity and conserve or improve on its plant species composition. In view of a better understanding of browse/browser interaction in subtropical arid savannah, Nguni goats were adopted as our model browser considering their socioeconomic importance to local, regional and global economy. The primary objective of this research was to determine the seasonal and plant species trend of diet selection indexed by intake and foraging efficiency indexed by intake rate. The secondary objective was to investigate how plant morphological variables such as spinescence, shoot morphology such as long shoots as opposed to short shoots, and broad as against fine leaves, phenological variables such as evergreen versus deciduous species, and plant chemical components including: crude protein, neutral detergent fibre (NDF), acid detergent fibre (ADF), hemicellulose, cellulose, acid detergent lignin and condensed tannins relate and possibly explain the observed patterns. Six browse plants, Acacia nilotica, Acacia robusta, Ehretia rigida, Euclea crispa, Rhus lancea and Ziziphus mucronata were used in the first experiment to determine short term intake during the dry and rainy seasons. In the second experiment, 10 browse plants: Acacia nilotica, Acacia robusta, Combretum epiculatum, Dicrostachys cinerea, Ehretia rigida, Euclea crispa, Gymnosporia buxifolia, Rhus lancea and Ziziphus mucronata were used to determine short term intake rate in the dry, early rainy and late rainy seasons. Diet selection was significantly affected by species (F5,60= 31.87 ; p< 0.05) and the interaction between seasons and species (F,60= 2.52; p= 0.039). Intake was not significantly higher in the rainy relative to the dry season, 3.94 ± 0.42a gDM compared to 3.57 ± 0.42a gDM. Rhus lancea and A. robusta were the most preferred species in both seasons, while Z. mucronata was more preferred in the dry season than E. crispa but in the rainy season it was the opposite. Dichrostachys cinerea and A. nilotica were the least preferred in both seasons, but with improved intake of D. cinerea in the rainy season, whereas that of A. nilotica declined significantly. Intake of plant species with long shoots, which were also broad leafed, was significantly higher than that of old short shoot species (t= -3.99; df= 65.80; p= 0.0002). Similarly, intake of evergreen species was significantly higher than that of deciduous species (t= 5.22; df= 34.02; p< 0.0001). Cellulose in the rainy season positively correlated with intake (r= 0.85; n= 6; p= 0.031), bite number cropped (r= 0.98; n= 6; p= 0.001) and browsing time (r= 0.93; n= 6; p= 0.007). In the dry season there was no correlation of any plant chemical components with intake except cellulose that correlated with the intake variable of bite size (r= 0.87; n= 6; p= 0.023). The following regression equation was generated from the correlation to model intake: Intake= 0.68 + BS (3.07), (R2= 0.71; p< 0.05), where BS= bite size. Intake rate varied amongst species (p< 0.05), as well as seasons (p< 0.05). Instantaneous intake rate in the dry season were highest for A. caffra and G. buxifolia, followed by C. apiculatum, R. lancea, E. crispa, A. robusta and Z. mucronata. The bottom tier comprised of E. rigida, D. cinerea and A. nilotica. At the onset of the rainy season, A. robusta, A. caffra and R. lancea had the highest instantaneous intake rate, followed by C. apiculatum, E. crispa and Z. mucronata. The lowest instantaneous intake rates were derived from D. cinerea, E. rigida, G. buxifolia and A. nilotica. At late rainy season, A. robusta, A. caffra, C. apiculatum, E. crispa and R. lancea yielded the highest intake rate, followed by D. cinerea, G. buxifolia and Z. mucronata in the middle tier, and the least were derived from E. rigida and A. nilotica. Acacia caffra, A. robusta, R. lancea, C. apiculatum and E. crispa featured amongst species with the higest intake rate in all three seasons, whereas G. buxifolia from which one of the highest intake rates was derived in the dry season declined to amongst those with the least in both early and late rainy seasons. Ehretia rigida, D. cinerae and A. nilotica were consistent in all three seasons as the least efficiently foraged Browses with long shoots were more efficiently foraged upon than those with short shoots (t= -3.2; df= 284.64; p< 0.002). Evergreen plant species yielded higher instantaneous intake rate relative to deciduous species (t= 2.02; df= 278.01; p< 0.044). Intake rate of spinescent relative to spineless species was not significantly different but more bites were cropped from spinescent relative to spineless species (t= 2.80; df= 256.77; p= 0.006). Bite sizes were smaller for spinescent relative to spineless species (t= -3.30; df= 227.4; p= 0.001). There were significant positive correlations of cellulose with intake rate (r= 0.7; n= 10; p= 0.023), and with condensed tannins (r= 0.7; n= 10; p= 0.022) in the dry season. Additionally, cellulose also had a positive correlation with bite size in the same season (r= 0.7; n= 10; p= 0.016). At early rainy season, there was no correlation of intake with any of the plant chemical components, whereas, NDF (r= 0.6; n= 10; p= 0.044), hemicellulose (r= 0.8; n= 10; p= 0.012) and condensed tannins (r= 0.7; n= 10; p= 0.032) all correlated positively with browsing time at early rainy season. The following regression equations were derived to model intake rate and some intake rate related variables: (1) intake rate= 0.433 + BSDM (0.081), R2= 0.68, p< 0.05 and BSDM= bite size dry matter; (2) Bite rate= 0.503 –BSDM (0.147), R2= 0.597, p< 0.05 and BSDM= bite size dry matter; (3) Bite size dry matter= 1.713 – BR (4.210), R2= 0.597 ,p< 0.05 and BR= bite rate, and (4) Intake dry matter= 3.804 + BSDM (0.865), R2= 0.607, p< 0.05 and BSDM= bite size dry matter. Diet selection and foraging efficiency were both influenced more by shoot and leaf morphology than by spinescence. Plant chemistry on the other hand had diverse and inconsistent effect on diet selection and foraging efficiency trends. The results therefore have important and far reaching implications for Nguni goat and goat production as a whole in the bush veld of Gauteng and related ecological zones. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.
13

Molecular and biochemical analysis of the diet of the black rhinoceros

Kgopa, Ananias Hodi 15 July 2013 (has links)
The black rhinoceros, Diceros bicornis, is listed as critically endangered. The black rhinoceros population in the Great Fish River Reserve (GFRR) has increased steadily to a current estimate of one hundred animals since the re-introduction of four animals in 1986. In an effort to contribute to the effective conservation and management of this species, dietary composition was studied in the medium Portulcaria thicket vegetation of the GFRR. This study used a molecular approach to determine the diet of the black rhinoceros of the GFRR by sequencing the ribulose bisphosphate carboxylase large subunit (rbcL) gene in plants and dung. Twenty-three plant species were collected from the reserve, and 802 bp of the rbcL gene were sequenced. These plant sequences were used as a reference database for the identification of plant sequences generated from black rhinoceros dung. Initial studies investigated the amplification, cloning and sequencing of DNA extracted from the dung samples which indicated the viability of the molecular approach. Thereafter, dung generated rbcL DNA was analyzed by GS FLX sequencing. Of the plant sequences identified by comparison to the GenBank database, Carissa bispinosa was the most prevalent. The study further characterized the antioxidant activities and phenolic content of plants eaten by the black rhinoceros using four different assays. Phyllanthus verrucosus, Putterlickia pyracantha, Maytenus capitata, Euclea undulata and Ozoroa mucrunata consistently had high antioxidant activities when assayed against 2,2-azinobis (3-ethyl benzothiazolium-6-sulfonic acid) (ABTSʹ⁺), 2,2-diphenyl-1-picrylhydrazyl (DPPHʹ), and ferric reducing antioxidant potentials (FRAP) and phenolic content when evaluated using the Folin-Ciocalteu assay. The majority of plants investigated showed low antioxidant potentials and low phenolic content. The extent to which antioxidants influenced the browse selection by the black rhinoceros remains inconclusive.
14

Determination of the botanical composition of black rhinoceros (Diceros bicornis) dung using the rbcL gene as a molecular marker, and analysis of antioxidant and phenolic content of its browse

Bulani, Siyavuya Ishmael 25 June 2013 (has links)
The black rhinoceros remains one of the world's extremely endangered species despite a variety of policies to protect it. The black rhinoceros population at the Great Fish River Reserve (GFRR) in the Eastern Cape in South Africa has increased steadily since their re-introduction in 1986. This megaherbivore is a browser, with a diet obtained largely from the short and medium succulent thicket of the GFRR. Knowledge of the preferential diet of the black rhinoceros on the reserve is an important factor for the effective management of the land and the herbivores that compete for its resources. The dietary preferences of the black rhinoceros at the reserve have been established using backtracking methods. In this study the rbcL gene was used to establish an rbcL gene database of the plants from the GFRR and determine the botanical composition of the black rhinoceros dung from the GFRR. Due to the limited number of rbcL gene plant sequences from the GFRR deposited in the GenBank database, 18 plant species from the GFRR were sequenced. Sequence analyses between the partial rbcL gene sequences generated were able to distinguish between plants down to species level. Plant species from the family Euphorbiaceae and Fabaceae showed sequence variation at intra-specific level compared to those of Tiliaceae which were more conserved. The generated rbcL gene sequences from seasonal dung samples were compared to the rbcL gene sequenced from 18 plant species obtained from the GFRR and those from the GenBank database. A wide range of plant species were identified from the dung samples. There were no major differences in botanical composition between the dung samples, except that Grewia spp. were found to dominate in almost all seasons. The results obtained on the free radical scavenging activity of the extracts against 2,2-Diphenyl-l-picrylhydrazyl (DPPH) increased in the order of methanol > ethyl acetate > chloroform. The DPPH free radical scavenging activity of the methanol plant extracts increased in the order Brachylaena elliptica > Plumbago auriculata > Grewia robusta > Azima tetracantha. Methanol extracts on the TLC plate sprayed with Fe³⁺-2,4,6-Tri-2-pyridyl-s-triazine (TPTZ) showed that the compounds present in the extracts react differently to ferric ion, with most compounds unable to reduce ferric ion. Furthermore the methanol extracts were able to exhibit reduction potentials vs. Ag/AgCl at low concentrations. The compounds in the extracts were shown to be phenolic acids and flavonoid glycosides.

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