Author : Elton Moyo.

Introduction

Livestock plays a major role in the agricultural sector in developing nations, and the livestock sector contributes 40% to the agricultural GDP. Global demand for foods of animal origin is growing and it is apparent that the livestock sector will need to expand (FAO, 2009). Livestock are adversely affected by the detrimental effects of extreme weather. Climatic extremes and seasonal fluctuations in herbage quantity and quality will affect the well-being of livestock, and will lead to declines in production and reproduction efficiency (Sejian, 2013). Climate change is a major threat to the sustainability of livestock systems globally. Consequently, adaptation to, and mitigation of the detrimental effects of extreme climates has played a major role in combating the climatic impact on livestock (Sejian et al., 2015a).

 There is little doubt that climate change will have an impact on livestock performance in many regions and as per most predictive models the impact will be detrimental. Climate change may manifest itself as rapid changes in climate in the short term (a couple of years) or more subtle changes over decades. Generally, climate change is associated with an increasing global temperature. Various climate model projections suggest that by the year 2100, mean global temperature may be 1.1–6.4 °C warmer than in 2010. The difficulty facing livestock is weather extremes, e.g. intense heat waves, floods and droughts. In addition to production losses, extreme events also result in livestock death (Gaughan and Cawsell-Smith, 2015). Animals can adapt to hot climates, however the response mechanisms that are helpful for survival may be detrimental to performance. In this article we make an attempt to project the adverse impact of climate change on livestock production.

Feeds and feeding management

More recently the nutritional mitigation strategy to reduce enteric methane emission from ruminants was extensively reviewed. A number of techniques exist to reduce methane emissions from enteric fermentation from ruminants. These methods include, improving the quality of the roughage, improving grazing practices, use of rotational grazing, inclusion of legumes, feeding highly digestible forages. Increasing forage digestibility and digestible forage intake will reduce methane emission from rumen fermentation (Rama Prasad 2015). Composition of feed has some bearing on enteric fermentation and the emission of CH4 from the rumen or hindgut. The volume of feed intake is related to the volume of waste product. The higher the proportion of concentrate in the diet, the lower the emissions of CH4. Increasing feed efficiency and improving the digestibility of feed intake are potential ways to reduce Green House Gas (GHG) emissions and maximize production and gross efficiency, as is lowering the number of heads. All livestock practices such as genetics, nutrition, reproduction, health and dietary supplements and proper feeding (including grazing) management. That could result in improved feed efficiency need to be taken into account.

 Proper pasture management through rotational grazing would be the most cost-effective way to mitigate GHG emissions from feed crop production. Animal grazing on pasture also helps reduce emissions attributable to animal manure storage. Introducing grass species and legumes into grazing lands can enhance carbon storage in soils. Feeding steam flaked- or high-moisture corn decreases enteric methane production by about 20% compared to feeding dry rolled corn-based high concentrate finishing diets because of more efficient digestion of starch in the rumen. Steam flaking may also decrease methane emissions from manures because it decreases the concentration of starch in the feaces.

Breeds and Breeding.

The use of multi-species and multi-breed herds is one strategy that many traditional livestock farmers use to maintain high diversity in on-farm niches and to buffer against climatic and economic adversities (Hoffmann, 2003). Such traditional diversification practices are useful for adaptation to climate change. Seo & Mendelsohn (2007, 2008) modelled that small farms in developing countries were found more climate change resilient due to their more diverse species portfolios, the ease with which they can shift between species and diversify, and their reliance on goats and sheep. On the contrary, commercial dairy and beef operations were more vulnerable than small farms, because their specialized nature makes it difficult for them to switch to other species. Several livestock species-level models that take into account the direct effects of climate change together with changes in agro-ecological conditions and production systems indicate that farmers will switch from dairy cattle and chickens towards small ruminants goats and sheep as temperature rises.

Genetic improvement is an important tool to accumulate response to selection and it can be used to reduce emissions, mainly through three approaches:

• Intensification of animal production – Breeding for improved efficiency of the animal leads to reduction of the total number of heads required to meet a given production level. An estimated drop of 8% of emissions might be obtained by reducing the number of farmed animals. From a range of production and fitness traits breeding animals traits, breeding studies have reported feed efficiency to have a large impact on the reduction of GHG emissions from dairy systems.

• Improvement of system efficiency – This is mainly based on the improvement of functional traits that can reduce wastage from the system and therefore GHG emissions. Garnsworthy (2004) reported a reduction of 10 to 11% in CH emissions if dairy fertility is improved. Fertility has a major effect on the replacement rate of the herd because scarce reproductive performances are associated with a higher number of young livestock to be reared. At the genetic level, the improvement of milk yield over the past 20 years has been associated with a decrease of fertility. Increased milk yield is beneficial to reduce CH emission per unit of product, but it is important that effects of reduced fertility do not outweigh them. Therefore, in the long term, fertility traits included in a selection index should be considered a positive strategy to reduce environmental impact as much as to preserve fertility.

• Direct reduction of GHG emissions through breeding. The direct reduction of GHG emissions using selection to identify animals that are high or low GHG emitters is a valid mitigation strategy. Many factors infuence ruminal CH emissions, including feed intake and composition and alterations in the ruminal microflora. Different strategies have been used to suppress methanogenesis including chemicals, antimicrobials, vaccination, organic acids and microbial feed additives, each with limited success.

Grazing Land in a changing Climate

The impacts of climate change on grazing lands and the livestock operations that depend on them will vary by region, type of grazing land, vegetation community, and the type of livestock. These impacts are superimposed upon other factors such as land ownership, historical and current management, demographic changes just to mention a few. For rangelands, warming temperatures and precipitation changes may change competitive interactions between plant species, favouring invasive species over native species. Rising CO2 is likely to enhance rangeland productivity while improving water use eficiency, but this could also benefit undesirable species over preferred native species. In some areas, rising temperatures and a longer growing season could improve forage production, whereas in others rising temperatures exacerbate drought by driving increased losses to evaporation. A trend to more extreme precipitation events will lead to increased flooding and erosio. Increased veld fire events are also likely, especially where invasives such as cheatgrass become dominant in the rangeland.

 Three elements that can impact the success of grazing operations include the seasonal distribution and quantity of forage, the inter-annual reliability of forage production, and forage nutritional value. Using conservative stocking rates, varied season of grazing, optimizing herd size and composition, identifying reserve forage, strategic distribution of water, proactive vegetation management and changes in enterprise structure are examples of rangeland management practices that can help livestock producers adapt to the negative impacts of climate change. Most of these practices are also relevant to pasture systems. However, because pasture systems are highly managed and often smaller in size than rangeland systems, there is more latitude in developing resilient management techniques that sometimes have more in common with cropland agriculture.

Manure Management.

Poor manure management practices are common on much of the world’s farms, as farmers

lack awareness about the value of livestock manure as a fertilizer and fuel. Manure is often

disposed of in piles, slurries or lagoons, which can lead to significant emissions of the

greenhouse gas methane, as well environmental degradation, negative health impacts, and the

loss of valuable nutrients that could be added to soil. Managing manure to reduce emissions can be economically viable for larger enterprises or cooperative facilities that use the captured methane to generate heat and electricity. For small operators, the offset value alone is unlikely to warrant the large capital cost of infrastructure. Reducing greenhouse gas emissions from livestock manure

Measures include:

• manure stockpile aeration and composting reduces methane emissions
• adding urease inhibitors to manure stockpiles can reduce nitrous oxide emissions; urease inhibitors are chemical additives that stop or reduce the rate that urea (found in animal urine and manure) is converted to nitrous oxide.

Using manure to capture and use methane on-farm – Livestock industries have shown increased interest in biogas (methane) capture-and-use systems, such as covered ponds and the flaring or combustion of the captured biogas to provide heat or power. These systems are common in Europe but not in Australia, and may be profitable, regardless of offset income, because of the energy production and the trading of renewable energy certificates. Biogas generation systems can reduce greenhouse gas emissions and improve farm productivity for intensive livestock farmers (mainly pork and dairy farmers). There are 3 eligible activities under the Emission Reduction Fund eligible emissions reduction activities. With a biogas generation system, large volumes of manure are digested under low-oxygen conditions to produce biogas that is subsequently combusted to destroy methane and produce heat or electricity. The waste sludge is normally returned to the land as fertiliser, either as slurry or pellets.