Plenary: Climate Change

The impact of global warming and continued uncontrolled release of greenhouse gases (GHG) has twofold implications for the livestock industry, and consequently food security. Firstly, the continuous increase in ambient temperature is predicted to have a direct effect on the animal, as well as indirect effects associated with feed sources, ecosystem changes and diseases. Secondly, the responsibility of livestock production is to limit the release of GHG or the carbon footprint, in order to ensure future sustainability. This presentation reviews the following targeted interventions: (1) The use of indigenous and adapted genotypes can be beneficial in the era of climate change. Matching of genotypes to production environment assumes that there are genotypes that could be matched more easily with the production environment. In this regard awareness of indigenous livestock is important; (2) Early warning systems should be developed. Projections of future changes in heat stress under climate change, as well as medium-range and seasonal prediction models for heat stress in cattle as an early warning system for farmers is important; (3) Alternative breeding objectives and biotechnology based breeding programs that will optimize climate smart beef production should be developed. An effective way to reduce the carbon and water footprint from livestock is to reduce the livestock numbers and increase the production per animal, thereby improving their productivity. In case of the Afrikaner breed cow efficiency improved by 18% over a period of 33 years, which reduced the carbon footprint by 12%. A breeding objective that aims to improve the kg calf weaned per Large-Stock Unit (LSU) mated is thus being developed; (4) Alternative production systems (e.g. crossbreeding) to improve the production efficiency of beef cattle should be characterized. This can play a significant role in reducing the carbon footprint from beef production. Evidence will be presented that the kg calf weaned/LSU mated can be improved by almost 50% through structured crossbreeding, whereas 27% less feed is consumed between weaning and harvest; (5) Quantification of the effect of weather patterns on fertility and growth of beef cattle in warmer parts of the country is essential. It will be demonstrated that the severe drought and extreme heat of the 2015/2016 summer had a negative effect on the performance and fertility of continental sired genotypes; and (6) The impact of changes in livestock feed-grain availability and price is important. How long will we still have the luxury to feed grains to animals instead of people? No single organization can perform on its own. The combination of sources of excellence to conduct research and development in climate smart livestock production is therefore essential.

Recently, increasing evidence for global warming has amplified the need to validate on-farm greenhouse gas (GHG) mitigation strategies. Ruminants have been identified as the single most important source of anthropogenic methane (CH4) emissions, of which CH4 is a potent GHG. Several CH4 mitigation strategies have been proposed, but most lack the practicality to be adopted on farm level. Concentrate supplementation has been identified as a CH4 mitigation strategy that is most likely to be adopted on farm level. The aim of this research was to determine the extent to which concentrate supplementation can reduce enteric CH4 from dairy cows grazing pasture during late summer and early spring. Thirty-six multiparous Jersey cows were subjected to a complete randomised block design and allocated to one of three treatment groups. The treatments differed by means of concentrate feeding level: 0, 4 and 8 kg/d (as fed basis). A 14 d dietary adaptation period was implemented. Cows grazed perennial ryegrass (Lolium perenne) dominant pasture during early spring and kikuyu (Pennisetum clandestinum) dominant pasture during late summer. Individual CH4 emissions were measured using the sulphur hexafluoride tracer gas technique and pasture intake was estimated using TiO2 as external marker and indigestible neutral detergent fibre as an internal marker. Pasture measurements and milk production parameters were also recorded. Milk yield, energy-corrected milk (ECM) yield, total dry matter intake (DMI) and milk lactose content increased linearly (P < 0.05), while pasture intake decreased linearly (P < 0.05) with increasing concentrate feeding level, irrespective of season. Methane production (mean of 294 g/d) and CH4 yield (mean of 19.0 g/kg of DMI) were unaffected (P > 0.05) by treatment on ryegrass dominant pasture, but increased linearly (P < 0.05; 323 to 378 g/d) and decreased linearly (P < 0.05; 29.1 to 25.1 g/kg of DMI), respectively, with increasing concentrate feeding level on kikuyu-dominant pasture. Furthermore, CH4 intensity (20.4 to 15.9 g of CH4/kg of milk yield) decreased linearly (P < 0.05) with increasing concentrate feeding level on ryegrass-dominant pasture, but decreased (P < 0.05; 35.5 to 21.1 g/kg of milk yield) even more on kikuyu-dominant pasture. Methane mitigation efficacy (40% vs 20%) of concentrate supplementation was more prominent on kikuyu-dominant pasture than ryegrass-dominant pasture. Kikuyu has an inherently higher fibre content than ryegrass, and the fermentation of fibre increases CH4 emissions, hence providing more opportunity to reduce CH4 emissions in kikuyu-dominant pasture systems.

Climate change is a subject of global environmental concern. The increased production of greenhouse gas (GHG) emissions, particularly carbon dioxide, methane and nitrous oxide, is considered as an important cause of climate change. Although there is no single definition for climate change, it can be defined as the change that can be attributed directly or indirectly to human activity that alters the composition of the atmosphere and which is in addition to natural climate variability observed over comparable periods. Agriculture is immensely affected by climate change but it also contributes to climate change in various ways. The livestock sector is viewed as one of the major contributors to climate change mainly due to enteric fermentation emissions followed by, manure fermentation emissions (waste products) and emissions released from the production of feed and forage. Small scale farmers are the worst affected by changes in climate since they rely heavily on the natural resource base for their livelihoods. Therefore, there is a need to explore alternative options for the resource-deprived farmers. One such intervention is climate smart agriculture (CSA). This is agriculture that sustainably increases productivity, resilience (adaptation), mitigation efficacy of GHG emissions and enhances attainment of food security and development goals while protecting the environment against degradation. Various climate smart options are recommended for sustainable livestock production. These include feed related interventions, livestock production management, environmental management and socio-political and financial interventions. This review will focus on feed related interventions and livestock production management (adaptation) options for reducing GHG emissions, increasing forage quantity and quality, and increasing livestock productivity.

There is general consensus that the Western Cape is likely to become hotter and drier under the influence of climate change. Sheep are commonly reared in open extensive areas, devoid of shade cover, to maximize the grazing area. This predisposes sheep to direct solar radiation and excessive heat, which may compromise animal welfare. This study investigated the effect of availing shade offered by trees to neonatal lambs on common of heat stress indicators (rectal temperature and respiration rate) as well as early lamb growth and survival. Groups consisting of 8-10 pregnant ewes of both the South African Mutton Merino (SAMM) and Dormer breeds were randomly allocated to 10 kikuyu (Pennisetum clandestinum) paddocks with natural shade from trees and nine comparable paddocks without shade. Heat stress indicators were recorded from noon on the day following the birth of individual lambs (i.e. within 24 h of birth, presumably at the time daily temperatures peaked), while the lambs were identified with their dams and recorded for birth weight and birth status. Daily climate statistics were obtained from a nearby weather station. Linear models, including treatment (shade vs. no shade), breed (Dormer vs. SAMM), sex (ram vs. ewe), dam age (2-5 years) and birth status (single vs. multiple) were fitted as fixed effects. Climate data were included as regression variables and interacted with shade treatment and breed. There was an interaction (P< 0.05) between maximum daily temperature and shade treatments (access to shade or no access to shade) for both rectal temperature and respiration rate. The rectal temperature and respiration rate of lambs in shaded paddocks generally did not increase on days with an increased ambient temperature relative to cooler days. In contrast, the rectal temperature and respiration rates of lambs increased substantially in unshaded paddocks on hot days. Tailing weight and lamb survival to tailing were not influenced by providing shade when compared with the unshaded paddocks. Maximum temperature thus had the greatest (P< 0.05) impact on lambs without shade when exceeding 30⁰C, as they were unable to maintain rectal temperatures and respiration rates at basal rates. In contrast, lambs in shaded paddocks could maintain their respiration rate and rectal temperatures at basal levels, even on hot days. In conclusion, lambs in unshaded paddocks were still able to accommodate the periods of excessive heat they were exposed to, by returning to their basal metabolic rate during the cooler nights and on cool days, since the provision of shade did not affect their production. However, the provision of shade had clear short-term animal welfare benefits by alleviating immediate heat stress resulting from high ambient temperatures on hot days.