Direct greenhouse gas emissions of the South African small stock sectors

There are increasing concerns about the impact of agriculture and livestock production on the environment. As a result, it is important to have accurate estimations of greenhouse gas (GHG) emissions if reduction measures are to be established. In this study the direct GHG emissions from South  African sheep and goats during 2010 were calculated. Calculations were done per province and in total. The Intergovernmental Panel on Climate Change (IPCC) methodology, adapted for tropical production systems, was used to calculate methane (CH4) and nitrous oxide (N2O) emissions on a Tier 2 level. Small stock is a key methane emission source in the South African livestock sector, and is responsible for an estimated 15.6% of the total livestock emissions. Small stock contributed an estimated 207.7 Giga gram (Gg) to the total livestock methane emissions in South Africa in 2010, with sheep producing 167 Gg and goats producing 40.7 Gg.  Calculated enteric methane emission factors for both commercial and communal sheep of 8.5 kg/head/year and 6.1 kg/head/year, respectively, were higher than the IPCC default value of 5 kg CH4/head/year for developing countries. A similar tendency was found with goat emission factors. The highest sheep and goat methane emissions were reported for the Eastern Cape province, primarily because of animal numbers.Keywords: Greenhouse gas, methane, nitrous oxide, sheep, goat

Direct methane and nitrous oxide emissions of monogastric livestock in South Africa

There are increasing concerns about the impact of agriculture and livestock production on the environment. In this the greenhouse gas emissions (GHG) from South African pigs, ostriches, horses, donkeys, mules and poultry were calculated, using 2010 production data on a provincial basis. The  Intergovernmental Panel on Climate Change (IPCC) methodology adapted to tropical production systems was used to calculate methane (CH4) and nitrous oxide (N2O) emissions. The non-ruminant sector is a minor GHG contributor compared with ruminant CH4 and N2O emissions. The pig industry and ostrich industry both contribute approximately 8 Gg (Giga gram) CH4 /year. The poultry industry is the largest direct N2O producer of the non-ruminant  livestock industries, contributing 2.3 Gg/year or 92.8% of the total non-ruminant N2O emissions.Keywords: Greenhouse gas, pigs, horses, ostriches, broiler, laye

Direct methane and nitrous oxide emissions of South African dairy and beef cattle

The objective of this study was to estimate direct methane and nitrous oxide emissions of South African dairy and beef cattle in total and per province using the Tier 2 methodology of the Intergovernmental Panel on Climate Change (IPCC), but adapted for tropical production systems. Dairy and beef cattle in 2010 contributed an estimated 964 Giga gram (Gg) or 72.6% of the total livestock methane emissions in South Africa. Beef cattle in extensive systems were the largest contributor (83.3%), followed by dairy cattle (13.5%), and feedlot cattle (3.2%). The enteric methane  emission factors for dairy cattle of 76.4 kg CH4/head/year and 71.8 kg CH4/head/year for concentrate fed and pasture-based production systems, respectively, were higher than those reported by other developing  countries, as well as the IPCC default value of 46 kg CH4/head/year for developing countries. The beef cattle methane emission factors of 78.9 kg CH4/head/year and 62.4 kg CH4/head/year for commercial and  emerging/communal cattle, respectively, were similar to those reported by other developing countries, but higher than the IPCC default value of 31 kg/head/year. Primarily because of cattle numbers, Eastern Cape recorded the highest dairy and beef cattle methane emissions, whereas Gauteng showed the highest feedlot methane emissions. Keywords: Greenhouse gas, production systems, commercial, communal, feedlot, rangelan

Direct greenhouse gas emissions of the game industry in South Africa

Previous greenhouse gas (GHG) inventories did not include game as an emissions source. Recently game farming has become a recognized  commercial enterprise in the agricultural sector in South Africa, contributing approximately R10 billion to the sectorial gross domestic product. The objective of this study was to estimate methane (CH4) and nitrous oxide (N2O) emissions from privately owned game animals based on  international recognized methodologies. The emissions were calculated on the basis of a large stock unit (LSU) selecting different quality diets. Daily enteric methane emissions were estimated as 0.28, 0.22, and 0.18 kg CH4/LSU/day consuming diets of 55%, 65% and 75% digestibility,  respectively. The game industry contributed an estimated 131.9 Giga grams (Gg) of methane annually to agricultural emissions with the  provinces of Limpopo, Eastern Cape and Northern Cape being the three largest contributors with 43.4, 37.3 and 21 Gg methane, respectively. The total privately owned game population was estimated at 299 1370  animals, utilizing 20.5 million hectares.Keywords: Methane, nitrous oxide, wildlife, emission factor

Ensiling quality of maize as influenced by the addition of wet distillers grains with soluble

Wet distillers grains with soluble (WDGS) were blended with whole maize plants on an as-fed basis at 0%, 20%, 30%, and 40% and ensiled in 3 L bottles to evaluate the silage fermentation characteristics and ensiling quality in a complete randomized design. Each treatment was ensiled in 15 mini-silos and three bottles were opened on days 7, 21, 42 and 120. Each treatment was sampled for chemical composition and silage fermentation parameters. There was a steady decrease in dry matter (DM) concentration of silage with increasing WDGS inclusion level over time. Initial pH (at day 0) decreased with increasing level of WDGS inclusion, with 40% WDGS inclusion recording the lowest pH (3.6) at day 120. Lactic acid concentration was slightly lower for WDGS-blended silages compared with the control. In contrast, the acetic acid concentration for WDGS-blended silage increased across all treatments, suggesting a possible diminished effect of clostridium bacteria in the silage owing to a reduced pH. The acid detergent fibre (ADF), neutral detergent fibre (NDF) and IVDOM (in vitro digestible organic matter) did not differ at the time of ensiling among treatments. During post ensiling, ADF increased slightly over time for WDGS-blended treatments (at 120 days). The results from this study indicated that WDGS could be ensiled effectively with maize plants without compromising silage quality.Keywords: Acetic acid, butyric acid, fermentation, lactic acid, preservation, silag

Enteric methane output from selected herds of beef cattle raised under extensive arid rangelands

Abstract Extensively raised beef cattle contribute to the highest levels of enteric methane (CH4) gas emissions among all livestock. Expensive techniques and logistics hinder monitoring of such gas. Therefore, the objective of this study was to use an inexpensive laser methane detector (LMD) apparatus to determine the enteric CH4 levels from a herd of beef cows raised on semi-arid rangelands. A total of 24 cows were selected from Boran and Nguni cows (n = 12 per breed) from two different farms. The parities of the cows were as follows: parity 1 (n = 6), parity 2 (n = 6), parity 3 (n = 6) and parity 4 (n = 6). An observer used a hand-held LMD to measure enteric CH4 emissions plumes during the late afternoon hours when the animals were resting (either standing or lying down). Point measurements (expressed in ppm/m) were taken for six consecutive days and repeated once after every three months. The ratio of CH4 output per kilogramme DMI was not different in within-breed and between-breed in both seasons. Generally, the dry season recorded the highest CH4 output per kilogramme of live weight of cow. For example, Boran cows in parity 2 produced the highest output of 1.0 ± 0.04 g CH4 per kilogramme live weight of cow while Nguni cows in parities 1, 2 and 4 each produced 0.9 ± 0.04 g CH4 per kilogramme live weight of cow in the dry season. All the animals maintained optimal body condition scores in both seasons (ranging between the lowest of 3.2 ± 0.01 and the highest of 3.4 ± 0.01). Based on the results of the study, it is concluded that cows from both herds produced higher CH4 per kilogramme live weight of cow in the dry season while maintaining optimal body condition scores in both seasons