Climate Change on Fertility and Reproductive Processes of Female Livestock

Introduction

Climate change is a growing concern of the contemporary world particularly in developing countries with the highest vulnerability yet, these countries are the least prepared to deal with the resultant effects, are financially limited due to high poverty levels and rely on natural resources heavily. Nyika (2020) confirmed that the effects of climate change are multifaceted and affect natural resources’ (land and water) sustainability, ecology, human and animal health with the situation in developing countries being dire due to their vulnerability and unpreparedness. Rising urbanisation trends and a growing population further exacerbate this trend. With climate change, the temperatures rise according to projections by Sheikh et al. (2017) who stated that by the year 2100 global temperatures will be 1.1 to 6.4 ℃ higher than the state at 2010 while rainfall, a main requirement for the fodder production will become more variable. Climate change trends are exacerbated by uncertainty, which makes it difficult to assess and predict its expected effects (Rust and Rust, 2013).

Globally, the livestock sector has been pressured by climate change events and effects in that the demand for animal products is high though optimisation of production capacities is hampered by several environmental conditions. According to Rojas-Downing et al. (2017), there is a growing livestock revolution whereby the preference to meat and meat products will rise from 258 to 455 million tonnes while that of milk and milk products will rise from 664 to 1077 million tonnes between 2006 and 2050. The effects of climate change, which will interfere with production capacity of livestock and will spill over these effects to the economy. This scenario is expected because 17% of the kilocalorie consumption and 33% protein intake is from livestock worldwide. Additionally, the livestock sector employs more than 1.1 billion people and most of them dwell in low income developing countries (Escarcha et al., 2018). There is a rising demand for livestock keeping and its indirect effects such as rising demand for agricultural land to grow fodder and high demand for consumptive water, which are consumers of natural resources (land and water). Consequently, the climate change situation is expected to worsen as the sector currently contributes to 14.5% of global greenhouse gas (GHG) emissions (Gerber et al., 2013). Consequently, climate change will affect livestock production by influencing competition with other natural resources, heat loss, biodiversity loss, vulnerability to livestock diseases and the quality and quantity of produced feeds (Sejian, 2013).

Of growing concern is the suggestion that climate change could interfere with the reproduction capacity of livestock. Kumar et al. (2017) reported that extreme climatic conditions induce stress on animals, which negatively influence reproduction and their production. Among the reported stresses include: reduced pasture and crop yield, frequent droughts and low rainfall leading to nutritional stress as well as heat stress due to increased soil radiation. The effects are more pronounced in animals reared under extensive rather than intensive production systems. Reproduction is an intricate process governed by environmental signals, metabolites and hormones in timed psychological and physiological procedures. The procedures include post-partum recovery, parturition, gestation, motherly recognition of pregnancy, embryonic development, puberty, transportation of gametes, fertilization and gametogenesis. Environmental factors such as nutrition, water access and quality, photoperiod, humidity and temperature affect the procedures when acting alone or in combination. The environmental factors usually aggravated by climate change adversely affect reproduction by interfering with the functions of hormonal systems and reproductive organs (Kumar et al., 2017). Effects such as dysfunctional sperm production and its reduced mobility to the egg and female hormonal abnormalities have been reported in sheep as a result of climate change (Sawyer and Jitik Narayan, 2019). Similarly, reduced egg production and interruption of ovulation in hens is documented as a result of extreme heat (Rojas-Downing et al., 2017). Reproductive roles of bulls, pigs and poultry have been disrupted as a result of climate change (Escarcha et al., 2018). Other general effects of climate change on reproduction include retarded foetal growth, abortion, still/ pre-mature births, embryonic deaths, failed fertilization, indifferent sexual behaviours and delayed puberty among others (Indu et al., 2014). This book chapter explores the effects of climate change on livestock fertility and reproductive systems and suggests a number of measures to mitigate and adapt to these changes with the cognition that climate change and its effects are inevitable.