Effects of soil type on density of trees and nutritive value of tree leaves in selected communal areas of South Africa

This study aimed to describe the distribution and nutritive value of woody species growing in clay-loamy and red-brown sand from selected localities of North West, South Africa. Three 2.2 km transects, radiating from homesteads, which served as replicates, were established at each of four selected grazing areas. Nine 10 × 10 m homogenous vegetation units (HVU), 20 m apart, were marked in each transect. Woody plant density, height and canopy cover (CC), were recorded, and chemical properties and degradability via in vitro ruminal fermentation of harvested leaves were measured. Raisin bush (Grewia flava), Buffalo thorn (Ziziphus mucronata) and Camel thorn (Vachellia erioloba) were the common species across both soil types. Soil type influenced (P <0.05) plant density, CC, total tree equivalent (TTE) and plant height. Areas with red-brown sandy soil had higher (P <0.05) total plant density (827.7 plant/ha), CC (9.6%) and TTE (2886.4 TTE/ha) than those with clay-loamy soil. Vachellia erioloba leaves in clay-loamy soil had the highest (P <0.05) crude protein content (151.2 g/kg DM). Leaves of Searsia lancea species that were harvested from both the clay-loamy and red-brown sandy soils had the highest (P <0.05) amounts of condensed tannins (0.915 AU550/200 mg and 0.917 AU550/200 mg, respectively). Searsia lancea leaves had the lowest (P <0.05) in vitro ruminal nitrogen degradability values in both soil types. The leaves of Z. mucronata and G. flava leaves have potential as protein supplements for ruminants owing to their higher crude protein content and in vitro ruminal N degradability. Keywords: canopy cover, feeding value, plant height, semi-arid, species diversity, tree equivalen

Effect of age on production characteristics of Boschveld indigenous chickens of South Africa reared intensively

The Boschveld indigenous chicken is a breed that was developed in South Africa for rural household free-range production of meat and eggs. A performance test was carried out to identify their production characteristics when reared intensively, and to estimate the responses of the production characteristics to age, based on optimization functions. Day-old chicks were procured from the breeder and reared to point of lay, with 1432 layers generating the data. Parameters include egg weight (g), egg number, hen day egg production (HDEP) (%), feed intake (g/b/d), bodyweight (kg), bodyweight gain (g), feed conversion ratio (FCR), feed efficiency (FE), and mortality from start of lay until 44 weeks old. There was a significant effect of age on all these production parameters, except for FCR, which was not affected significantly by age as the birds grew. On fitting a prediction and optimization function using a regression model, these parameters showed significant linear response to age: HDEP, feed intake (g), and bodyweight (kg), while significant quadratic responses were found in egg weight and FCR. The prediction model shows that at age 34, 52 and 65 weeks of lay, bodyweight, HDEP and feed intake respectively, would be optimized, while at age 36 and 43 weeks, FCR and egg weight respectively, would be optimized. This implies that Boschveld indigenous chicken production characteristics can be targeted at the appropriate age and can be optimized, given the age of lay that the birds are in.Keywords: Egg laying, egg production, intensive production,native breed, optimization function, regression mode

Spatial variation in density, species composition and nutritive value of vegetation in selected communal areas of the North West Province

PhD (Animal Science), North-West University, Mafikeng CampusThe study was designed to assess spatial variation in terms of density, species composition and nutritive value of vegetation in selected communal grazing lands located in the Ngaka Modiri Molema district municipality of the North West province. For the first study on tree species assessement, three 2.2 km transects, which served as replicates were established at each of the selected grazing areas. The three transects were placed at least 200 m from each other. Along each transect, points were marked within 500-700 m (considered as near sites), >700 m-1.4 km (middle site) and >1.4 km – 2.2 km (far sites) from the homesteads to form 9 sampling sub-transects. Three 10 m x 10 m homogenous vegetation units were marked at each sub-transect and spaced 20 m from each other. The homogenous units (HVU) were used to record density, height and canopy diameter of individual woody plants. Plant identification was carried out using a combination of scientific and indigenous local knowledge. A total of 21 browse species were found across all sites. Grewia flava and Acacia erioloba were the most dominant species in all soil types across the study areas. There was no significant effect of distance from the homesteads on density, canopy cover (CC), total tree equivalent (TTE) and plant height. There was a significant effect of soil type on density, canopy cover, total tree equivalent and plant height. The red-brown sand soil type had higher (P<0.05) total plant density (827.7 plant/ha), CC (9.6%); TTE (2886.4 TTE/ha) than in clay-loamy soil type area. Red-brown sand soil type area had higher (P<0.05) values for all height levels than clay-loamy soil type. For grass sampling and assessment of grass species composition, within each sub-transect, 10 m × 10 m homogenous vegetation unit (HVU) was marked. In each HVU, 1 m2 quadrat was randomly placed to sample soil and grass species resulting in a total of 9 samples per site. Grass samples (per each species) were collected per quadrat, oven-dried and milled through a 1 mm sieve for chemical analysis. A total of 28 grass species were identified in all study areas, of which 23 species were perennials. Twenty one percent of the total grasses were classified to be of high grazing value, 50% medium grazing value and 29% as low grazing value. Most of the highly palatable species were found at sites far from the homesteads. Cymbopogon pospischilii, Eragrostis bicolor and aristida species were the most commonly occurring grasses in many sites in the grazing area under clay-loamy (CL) and Red-brown sand (RBS) soil types. Sodium, P, K, Ca, Mg and Mn concentration was higher (P<0.05) in CL soil than in RBS soil. Iron concentration was higher in RBS soil than in CL soil. Tree and grass samples were collected and analysed for chemical and in vitro ruminal degradability. Eragrostis trichopora (100 CP g/kg) in Tsetse, Cynodon dactylon (62 and 66 CP g/kg) in Six-hundred and Makgobistadt, Melenis repens (70 CP g/kg) in Loporung communal area had the highest CP values than all other grass species in their respective areas. Cymbopogon pospischilii (540.6 g/kg DM) and E. trichopora (562.0 g/kg DM) had the highest (P<0.05) DM degradability values at 48 h at clay-loamy soil type grass species. All grass species harvested in Makgobistadt and Loporung communal areas had similar DM degradability values at 48 h. The highest crude protein content (P < 0.05) was recorded in leaves of Grewia monticola (190.4 g/kg DM) than in all other species in the study area. Although all the browse species contained lower amounts of tannins in their leaves, the highest (P<0.05) CT content was found in Dichrostachys cinerea leaves (0.993 and 1.044 AU550/200 mg) than all other browse species in the study areas. The last study was carried out to determine key characteristics of common grass species under controlled environmental conditions, including their phenological patterns, relative growth rates as well as their chemical composition, and in vitro ruminal degradability. Differences (P<0.05) were observed on morphological characteristics within grass species, growth stage and their interaction. Fingerhuthia africana had higher (P<0.05) CP content (102 g/kg) than all other grass species. Eragrostis bicolor had higher (P<0.05) number of tiller developed at reproductive stage than all other grass species. Due to different morphological characteristics and feeding value, these species could complement each other in rehabilitating the communal areas affected by heavy grazing. Changing the vegetation structure by reducing woody plant density in Makgobistadt and Loporung communal areas can create a conducive environment for open grasslands to occupy the communal area and create biodiversity within grass species.Doctora

Effect of harvesting site on mineral concentration of browse species found in semi-arid areas of South Africa

The objective of this study was to investigate the effect of the harvesting site on the mineral concentration of selected browse species found in semi-arid areas of South Africa (North West and Limpopo province sites). Five trees from each of the 52 woody browse species were randomly identified and harvested in the North West and Limpopo provinces, South Africa, dried and ground for laboratory analysis. One-way ANOVA was used to analyse the mineral composition of browse species that were not common in both harvesting sites, while a two-way factorial design within a completely randomized experimental design was used to analyse the mineral composition of browse species that were common in both harvesting sites. MANOVA tests were also used in order to assess the species and harvesting site effects on mineral concentrations of species common in both sites. Through ANOVA and MANOVA, there were significant species, harvesting site, and species × harvesting stage effects on all the measured parameters (both macro and micro mineral elements). Phosphorus and calcium concentrations were the highest in Adansonia digitata species, whereas the lowest was obtained in Androstachys jonhsonii browse species in the Limpopo harvesting site. Within each province, Schinus molle found in the North West site had the highest phosphorus, potassium and sodium values when compared to all species within the same province. Vachellia nilotica subsp. kraussiana, M. azedarach and Ziziphus mucronata found in Limpopo province had the highest level of magnesium when compared to other species found within the same province. Senegalia caffra, Grewia flava, Vachellia karroo, Vachellia nilotica subsp. kraussiana, Searsia leptodictya and Melia azedarach found in the Limpopo province had the highest phosphorus level when compared to the same species found in the North West province. Senegalia caffra, Peltophorum africanum, Grewia flava, Vachellia hebeclada and Terminalia sericea found in the North West province had the highest iron levels when compared to the same species found in Limpopo province. There is a need to provide supplementation to those animals exposed to species that have a lower concentration of certain elements