Measuring enteric methane emissions from individual ruminant animals in their natural environment

Ruminant livestock are an important source of meat, milk, fiber, and labor for humans. The process by which ruminants digest plant material through rumen fermentation into useful product results in the loss of energy in the form of methane gas from consumed organic matter. The animal removes the methane building up in its rumen by repeated eructations of gas through its mouth and nostrils. Ruminant livestock are a notable source of atmospheric methane, with an estimated 17% of global enteric methane emissions from livestock. Historically, enteric methane was seen as an inefficiency in production and wasted dietary energy. This is still the case, but now methane is seen more as a pollutant and potent greenhouse gas. The gold standard method for measuring methane production from individual animals is a respiration chamber, which is used for metabolic studies. This approach to quantifying individual animal emissions has been used in research for over 100 years; however, it is not suitable for monitoring large numbers of animals in their natural environment on commercial farms. In recent years, several more mobile monitoring systems discussed here have been developed for direct measurement of enteric methane emissions from individual animals. Several factors (diet composition, rumen microbial community, and their relationship with morphology and physiology of the host animal) drive enteric methane production in ruminant populations. A reliable method for monitoring individual animal emissions in large populations would allow (1) genetic selection for low emitters, (2) benchmarking of farms, and (3) more accurate national inventory accounting

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

Adapting sheep production to climate change

Apart from contributing to the climate change phenomenon, sheep production sys tem is also sensitive to its adverse impacts. This poses a great challenge for develop ing sheep sector around the world. Currently the economic viability of the sheep production system worldwide is jeopardized due to the devastating effects of cli mate change. Among the multiple climatic stresses faced by sheep, heat stress seems to hugely destabilize production efficiency of the animals. Heat stress jeopardizes the growth, wool, meat and milk production in sheep. Further, climate change leads to several vector borne diseases to sheep by compromising the immune status of the animals. The animal employs several adaptive mechanisms to maintain homeosta sis through behavioural, physiological, neuroendocrine, cellular and molecular responses to cope up to the existing climatic condition. Sheep also significantly contributes to climate change through enteric methane emission and manure man agement. Further, climate change can alter the rumen function and diet digestibility in sheep. Hence, enteric methane mitigation is of paramount importance to prevent both the climate change and dietary energy loss which may pave way for sustaining the economic return from these animals. Further, various other strategies are required to counter the detrimental effects of climate change on sheep production. The management strategies can be categorized as housing management, animal management and monitoring of climate, and these strategies are ultimately targeted to provide suitable microclimate for optimum sheep production. Nutritional inter ventions involving season-specific feeding and micronutrient supplementation may help the animal to sustain its production during adverse environmental conditions. Body condition scoring system developed specifically for sheep may help to opti mize economic return in sheep farms by minimizing the input costs. Finally, suffi cient emphasis must be given to develop appropriate adaptation strategies involving policymakers. These strategies include developing thermotolerant breeds using bio markers, ensured water availability, women empowerment, early warning system and capacity building programmes for all the stakeholders. These efforts may help in augmenting sheep production in the climate change scenario