Determining spatial and temporal variability in quantity and quality of vegetation for estimating the predictable sustainable stocking rate in the semi-arid savanna

This study assessed the importance of spatial and temporal variation in plant quality and quantity for determining sustainable stocking rates in game, commercial and communal ranches in semi-arid savanna of the Northern Cape Province, South Africa, in wet and dry seasons over a two-year period. We focussed on variation in plant biomass, phosphorus (P), crude protein (CP) concentrations and dry matter digestibility as parameters most likely to affect sustainable stocking rates. Habitat type had greater effects on plant quality, plant biomass and species composition than management type. The commercially-managed area had the highest tree density in the rocky habitat and lower plant quality than other management types. All of these features indicate that land degradation is occurring on commercial ranches in spite of rotational grazing and lower stocking density than on communal ranches. We recommend that commercial ranchers should introduce a greater variety of stock and/or game to reduce selective grazing of certain plant species. Quality measures (CP and P) gave more conservative predictions of stocking density than biomass. In this region of the Northern Cape, seasonally-inundated pan habitats are particularly valuable in spite of low-standing crop because they have the highest year-round quality. Contrastingly, ranchers should only lightly stock open savanna habitats, in spite of high standing biomass, because they have low vegetation quality and may be particularly susceptible to degradation and invasion by poisonous and unpalatable plants. Copyright © NISC Pty Ltd.Articl

Effects of herbivore exclosures on variation in quality and quantity of plants among management and habitat types in a semiarid savanna

The effects of grazing on plant biomass, plant quality, species evenness, species diversity and species composition were determined among management types (communal, commercial and game) and among habitat types (open savanna, rocky and pan) in a semiarid savanna in South Africa. Over three growing seasons we compared fenced and unfenced plots among all management and habitat types. Fenced plots had greater mean plant height as well as higher crude protein (CP) and phosphorus (P) yields (= concentration × biomass). The only significant difference in species composition between fenced and unfenced plots was observed in the pan habitat type during the third growing season. Negative effects of grazing were more pronounced in the commercially managed area than under other management types, although the higher abundance of poisonous plants under communal management is of considerable concern. The open savanna habitat had the highest plant biomass and lowest CP and P levels, while the reverse was true for the pan habitat type. Most parameters assessed showed significant effects between fenced and unfenced plots towards the end of the study only because species composition in fenced plots was altered by competition between species normally suppressed by grazing. © NISC (Pty) Ltd.Articl

Using faecal profiling to assess the effects of different management types on diet quality in semi-arid savanna

We used faecal profiling to assess diet quality of animals under three different management types in a semi-arid savanna, northwest of Kimberley, Northern Cape, South Africa. The levels of faecal crude protein (FCP) and faecal phosphorus (FP) of free-ranging springbok (Antidorcas marsupialis) and blue wildebeest (Connochaetes taurinus) on a game ranch, goats and cattle grazing in a communally-managed area, as well as cattle grazing under commercial management were determined in the wet and dry seasons over a period of two years. Plant and soil analyses were also conducted. Goats had the highest FCP and FP of all species in all seasons during the study. It appeared that selective feeders (goats and springbok) and short-grass feeders (wildebeest) do not suffer from low forage quality because their FCP and FP levels were above critical values during all seasons. Contrastingly, cattle need nutrient supplementation because their FCP and FP were below critical nutritional values during the dry seasons. Plant and soil chemical characteristics, especially soil P, had an influence on faecal quality during the study. Clay pans provide an important habitat because of the high soil quality and, consequently, high diet quality. Our surprising finding that faecal CP levels were higher under communal management than under commercial management may be ascribed to higher nutrient deposition (due to higher stocking rates) and greater diet selectivity available to free-ranging animals under communal management. Higher faecal CP and P levels in game animals may also be ascribed to unrestricted movement and, consequently, greater access to palatable plants. The results of this study demonstrate the value of faecal profiling for management of semi-arid savanna livestock and game. Copyright © NISC Pty Ltd.Articl

The effects of grazing, fire, nitrogen and water availability on nutritional quality of grass in semi-arid savanna, South Africa

The impacts of fire and grazing management on grass nutritional quality in semi-arid savannas may depend on inherent variation in rainfall and soil nutrient status. We examined the effects of grazing, fire, nitrogen addition, and watering treatments on the nutritional value of grass in a field experiment in the Northern Cape, South Africa. Surprisingly, water addition had no effect on grass quality and biomass in this dry savanna, perhaps because of the above-average rainfall during this study. Nitrogen addition resulted in increased levels of crude protein and biomass, as well as crude protein and gross energy in the early and late wet seasons, respectively. Grazing alone generally had little effect on grass quality, although grass in grazed plots had higher levels of crude protein (CP) in the late wet season and phosphorus (P) in the dry season. Grass biomass was greater in plots protected from grazing. There was more CP and P mass per unit area in fenced (ungrazed) plots during the wet season. Fire interacted with addition of nitrogen and grazing to increase grass quality. Soil nitrogen availability appears to be the most important factor affecting nutrient quality of grasses in the wet season in this semi-arid ecosystem. © 2010 Elsevier Ltd.Articl

Effects of dietary fibre level on rumen pH, total microbial count and methanogenic archaea in Bonsmara and Nguni steers

A study was conducted to evaluate the effect of the level of dietary fibre on rumen pH, total microbial count and methanogenic archaeacount of Bonsmara (225 ± 10.0 kg live weight) and Nguni (215 ± 10.0 kg live weight) steers. Nine steers per breed were used, aged 8 to 9 months. A 3 x 2 factorial experiment was executed with treatments allocated in a completely randomized design. The treatments were diets which included 64.3% neutral detergent fibre (NDF) for diet 1, 40.4% NDF for diet 2, and 29.9% NDF for diet 3. Steers were fed for 90 days and housed in individual pens. Rumen fluid was collected from steers using a stomach tube. Rumen fluid samples were taken immediately to the laboratory for microbial assay. Data were subjected to analysis of variance (ANOVA). The various levels of dietary fibre did not affect rumen pH and methanogenic archaea count. However, a low-fibre diet yielded high rumen total microbial count for Bonsmara steers and low rumen total microbial count for Nguni steers. Therefore, a low-fibre diet can be applied as a viable strategy to enhance rumen total microbial count in exotic beef breeds and crossbred cattle such as Bonsmara. Nguni steers fed a high NDF diet had higher rumen total microbial count than Nguni steers fed a low-fibre diet. Therefore, a high NDF diet can be used efficiently by feeding it to indigenous breeds and purebred cattle such as Nguni

Seasonal effects of Rhus lancea and Celtis africana on intake preference and physiological responses in South African indigenous goats

This study investigated the seasonal effects of Rhus lancea and Celtis africana leaves on preference, intake, weight, and serum metabolites in South African indigenous, mature, male goats. Twelve mature, male goats weighing 34 ± 5.9 kg (mean ± SD) were randomly allocated to two groups of six and kept in metabolic crates for periods of 21 days in October 2015 and March, May, and August of 2016. A browser diet of R. lancea and C. africana and a control diet (lucerne and concentrates) were randomly allocated to each group. Measurements taken included nutritional composition of browse per season, and browse preference, intake, weight changes, and serum metabolites in the goats. The acid detergent fibre (24–36%) and neutral detergent fibre (26.9–70.4 %) in R. lancea over the months were greater than in C. africana (50.3–53.2% and 49.4–55.4%, respectively). In the preference study, the goats preferred C. africana more in October (51.2 vs 48.8%), March (51.4 vs 48.6%), and May (54.3 vs 45.7%). Goats on the browser diet lost weight in March, May, and in August whereas those on the control diet gained weight. The serum urea concentration of goats consuming browser diets in May and August (1.8–3.3 mmol/l) was lower than the normal range, consistent with animals failing to derive their protein requirements from the diet. Goats prefer to browse C. africana more than R. lancea. The study also indicated the need for supplementation to meet maintenance requirements in animals fed R. lancea and C. africana.College of Agriculture and Environmental Science