Cryopreservation of Oocytes and Embryos: Current Status and Opportunities

The biochemical and metabolic activities of living cells are virtually stopped at ultralow temperature and they enter into a suspended state of animation. However, as such, exposure of living cells to ultralow temperature is associated with complex changes that reduce their survivability following freeze-thawing. Cryopreservation is the method for preserving living cells at ultralow temperature at genetically and physiologically stabilized state. Cryopreservation of oocytes and embryos is an integral part of the assisted reproductive technologies with many potential applications. Cryobanking of oocytes and embryos derived from genetically superior animals is promising for enhancing the outcome of planned breeding programs and conserving biodiversity of endangered animal species. Cryobanking can also ensure steady supply of oocytes and embryos for many downstream applications of assisted reproduction such as in vitro embryo production, embryo transfer, production of stem cells, and genetic engineering. Tremendous advancements have been made in this field over the past 5 decades and several methods have been demonstrated for cryopreserving oocytes and embryos in different species. This chapter focuses on the fundamental aspects of oocyte and embryo cryopreservation

Phenolic Composition, Fermentation Profile, Protozoa Population and Methane Production from Sheanut () Byproducts

Sheanut cake (SNC), expeller (SNE) and solvent extractions (SNSE) samples were evaluated to determine their suitability in animal feeding. The CP content was highest in SNSE (16.2%) followed by SNE (14.7%) and SNC (11.6%). However, metabolizable energy (ME, MJ/kg) was maximum in SNC (8.2) followed by SNE (7.9) and SNSE (7.0). The tannin phenol content was about 7.0 per cent and mostly in the form of hydrolyzable tannin (HT), whereas condensed tannin (CT) was less than one per cent. The in vitro gas production profiles indicated similar y max (maximum potential of gas production) among the 3 by-products. However, the rate of degradation (k) was maximum in SNC followed by SNE and SNSE. The t1/2 (time taken for reaching half asymptote) was lowest in SNC (14.4 h) followed by SNE (18.7 h) and SNSE (21.9 h). The increment in the in vitro gas volume (ml/200 mg DM) with PEG (polyethylene glycol)-6000 (as a tannin binder) addition was 12.0 in SNC, 9.6 in SNE and 11.0 in SNSE, respectively. The highest ratio of CH4 (ml) reduction per ml of the total gas, an indicator of the potential of tannin, was recorded in SNE (0.482) followed by SNC (0.301) and SNSE (0.261). There was significant (p<0.05) reduction in entodinia population and total protozoa population. Differential protozoa counts revealed that Entodinia populations increased to a greater extent than Holotricha when PEG was added. This is the first report on the antimethanogenic property of sheanut byproducts. It could be concluded that all the three forms of SN byproducts are medium source of protein and energy for ruminants. There is a great potential for SN by-products to be incorporated in ruminant feeding not only as a source of energy and protein, but also to protect the protein from rumen degradation and suppress enteric methanogenesis

GHG Emissions from Livestock: Challenges and Ameliorative Measures to Counter Adversity

Livestock and climate change are interlinked through a complex mechanism and serve the role of both contributor as well as sufferer. The livestock sector is primarily accountable for the emission of methane and nitrous oxide. Methane emission takes place from both enteric fermentation and manure management; whilst nitrous oxide emission is purely from manure management. Rumen methanogenesis due to emission intensity and loss of biological energy always remains a priority for the researchers. Greenhouse gas (GHG) emissions from manure are determined by storage conditions and the organic content of the manure waste. Due to large livestock population, India is a major contributor of enteric methane emission, while its contribution to the excrement methane is negligible. In this chapter, information pertaining to enteric methane emission, excrement methane and nitrous oxide emissions and ameliorative/precautionary measures for reducing the intensity of emissions have been compiled and presented

Mitigation of the Heat Stress Impact in Livestock Reproduction

Heat stress affects the fertility and reproductive livestock performance by compromising the physiology reproductive tract, through hormonal imbalance, decreased oocyte quality and poor semen quality, and decreased embryo development and survival. Heat stress decreases the secretion of luteinizing hormone and estradiol resulting in reduced length and intensity of estrus expression, increased incidence of anoestrus and silent heat in farm animals. Oocytes exposed to thermal stress lose its competence for fertilization and development into the blastocyst stage, which results in decreased fertility because of the production of poor quality oocytes and embryos. Furthermore, low progesterone secretion limits the endometrial functions, and subsequently embryo development. In addition, the increased secretion of endometrial prostaglandin F2 alpha during heat stress threatens the maintenance of pregnancy. In general, the percentage of conception rate was found to be reduced by 4.6% for each unit increase in temperature humidity index (THI) above 70, and heat stress during pregnancy further slows down the growth of the foetus and results in lower birth weight. In tropical and subtropical regions, during hot days, the testicular temperature may increase and impair both the spermatogenic cycle and semen quality, which culminates in decreased bull fertility. The effects of heat stress on livestock can be minimized via adapting suitable scientific strategies comprising physical modifications of the environment, nutritional management and genetic development of breeds that are less sensitive to heat stress. In addition, the summer infertility may be countered through advanced reproductive technologies involving hormonal treatments, timed artificial insemination and embryo transfer, which may enhance the chances for establishing pregnancy in farm animals

Livestock as Sources of Greenhouse Gases and Its Significance to Climate Change

This chapter outlines the role of livestock in the production of greenhouse gases (GHGs) that contributes to climate change. Livestock contribute both directly and indirectly to climate change through the emissions of GHGs such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). As animal production systems are vulnerable to climate change and are large contributors to potential global warming, it is vital to understand in detail enteric CH4 emission and manure management in different livestock species. Methane emissions from livestock are estimated to be approximately 2.2 billion tonnes of CO2 equivalents, accounting for about 80% of agricultural CH4 and 35% of the total anthropogenic CH4 emissions. Furthermore, the global livestock sector contributes about 75% of the agricultural N2O emissions. Other sources of GHG emission from livestock and related activities are fossil fuels used for associated farm activities, N2O emissions from fertilizer use, CH4 release from the breakdown of fertilizers and from animal manure, and land-use changes for feed production. There are several techniques available to quantify CH4 emission, and simulation models offer a scope to predict accurately the GHG emission from a livestock enterprise as a whole. Quantifying GHG emission from livestock may pave the way for understanding the role of livestock to climate change and this will help in designing appropriate mitigation strategies to reduce livestock-related GHGs

Differences in enteric methane emissions across four dairy production systems in the urbanizing environment of an Indian megacity

Low- and middle-income countries (LMICs) are rapidly urbanizing, leading to a high demand for high-quality animal products. Production increase is seen as a key to meeting this demand and reducing the global environmental impact of low-yielding dairy production system (DPS) often found in LMICs. Therefore, the present study assesses the relationship between enteric methane emissions and different dairy production strategies, taking DPS in the rural–urban interface of Bengaluru, an Indian megacity, as a case study. Twenty-eight dairy farms, evenly distributed across four DPS, were monitored for 1 year (eight visits at 6-week intervals). Following IPCC 2006 guidelines and a Tier 2 approach, enteric methane emissions from dairy cattle were calculated as carbon dioxide equivalents (CO2 eq). Dairy producers in ExtDPS, an extensive DPS found throughout the rural–urban interface of Bengaluru, fed their dairy cattle a high-quality diet, partly based on organic wastes from markets or neighbors, achieving 9.4 kg energy-corrected milk (ECM) per cow and day. Dairy producers in Semi-ADPS, a semi-intensive and rural DPS, fed an average quality diet and achieved the lowest milk production (7.9 kg ECM cow−1 day−1; p &lt; 0.05). Dairy producers in Semi-BDPS, another semi-intensive and rural DPS, relied on average quality but more abundant feedstuffs and achieved a production of 10.0 kg ECM cow−1 day−1. A similar milk yield (10.1 kg ECM cow−1 day−1) was achieved by IntDPS, an intensive and rural DPS. The intensity of enteric methane emissions was the highest in Semi-BDPS (1.38 kg CO2-eq kg−1 ECM; p &lt; 0.05), lowest in ExtDPS (0.79 kg CO2-eq kg−1 ECM; p &lt; 0.05), and intermediate in semi-ADPS and IntDPS. The results highlight the close relationship between the intensity of enteric methane emissions and the intensification strategies chosen by dairy producers based on locally available resources. They also underline the importance of region- and system-specific environmental assessments of production systems in LMICs

Biological role of melatonin during summer season related heat stress in livestock

Heat stress can cause a significant financial burden to livestock producers by decreasing all productive functions in livestock. The major strategies associated with relieving heat stress in livestock are through use of sheds, fans, or evaporative cooling. Such practices are not possible where the animals are reared in a semi-intensive system. This necessitates developing other strategies to counteract the adverse effects of heat stress. A new strategy involving the feeding of melatonin (MEL) has been evaluated by a few researchers. Melatonin has hypothermic and antioxidant effects and may counter the detrimental effect of heat stress on livestock production. The aim of the paper is to review evidence for and against the use of MEL as an anti-heat stress agent. The early suggestion of a functional antagonism between the pineal and the adrenal gland became additionally reinforced by experimental and clinical findings indicating that MEL may be able to protect the organism against heat stress-induced damages. Melatonin effectively protects against heat stress, by a variety of mechanisms. As animals in tropical countries are exposed to heat stress during much of the year, MEL with its potential beneficial effects may be useful as an anti-heat stress agent to prevent the loss of production

In vitro evaluation of graded level of Silkworm pupae (Bombyx mori) oil on methane production, fermentation characteristics, and protozoal populations

Aim: The present study was undertaken to evaluate the effect of variable levels of silkworm pupae oil and roughage: concentrate ratio on in vitro methane production, fermentation characteristics, and rumen protozoa population. Materials and Methods: In vitro gas production study (24 h) was performed with graded levels of silkworm pupae oil, namely, 0.5, 1, 2, 4, and 5% of the basal diet and four variable dietary regimes consisting roughage and concentrate in different proportions (70:30, 60:40, 50:50, and 40:60). At the end of incubation, gas samples were analyzed for methane, while fermented rumen liquor was used for protozoa enumeration. A separate set of incubations was carried out for the determination of in vitro dry matter digestibility. Results: Results from the in vitro studies revealed no adverse impact of the silkworm pupae oil supplementation up to 2% level on total gas production. However, supplementation beyond 2% has shown a reduction in total gas production. Incubation with variable levels (0.5-5%) of silkworm pupae oil with different dietary regimes indicated negligible (3-5%) to a substantial reduction (25-30%) on methane production. A graded decrement in methane production was recorded with increasing levels of silkworm pupae oil. Similarly, the protozoal populations were decreased from 10 to 51.5% with graded levels of silkworm pupae oil in different dietary regimes as studies did not reveal any significant (p>0.05) variation between 2 and 4% of oil supplementation. Conclusion: The silkworm pupae oil supplementation at 2% level decreases methane production by 12-15% without any adverse impact on feed fermentation. Oil supplementation may have a more pronounced effect on methane reduction if added to high roughage diet at in vitro conditions. However, in vivo, studies in ruminants are warranted to confirm the methane reduction with silkworm pupae oil supplementation

Methane mitigation potential of phyto-sources from Northeast India and their effect on rumen fermentation characteristics and protozoa in vitro

Aim: The aim of the study was to explore the anti-methanogenic potential of phyto-sources from Northeast region of the country and assess the effect on rumen fermentation characteristics and protozoa for their likely inclusion in animal diet to reduce methane emission. Materials and Methods: Twenty phyto-sources were collected from Northeast state, Assam, during March to April 2014. Phyto-sources were analyzed for their tannin content followed by screening for methane mitigation potential using in vitro system. The effect of tannin on methane production and other fermentation parameters was confirmed by attenuating the effect of tannin with polyethylene glycol (PEG)-6000 addition. About 200 mg dried phyto-source samples were incubated for 24 h in vitro, and volume of gas produced was recorded. The gas sample was analyzed on gas chromatograph for the proportion of methane in the sample. The effect of phyto-sources on rumen fermentation characteristics and protozoal population was determined using standard methodologies. Results: Results from studies demonstrated that Litchi chinensis, Melastoma malabathricum, Lagerstroemia speciosa, Terminalia chebula, and Syzygium cumini produced comparatively less methane, while Christella parasitica, Leucas linifolia, Citrus grandis, and Aquilaria malaccensis produced relatively more methane during in vitro incubation. An increase (p<0.05) in gas and methane production from the phyto-sources was observed when incubated with PEG-6000. Entodinimorphs were prominent ciliates irrespective of the phyto-sources, while holotrichs represented only small fraction of protozoa. An increase (p<0.05) in total protozoa, entodinimorphs, and holotrichs was noted when PEG-6000 added to the basal substrate. Our study confirmed variable impact of phyto-sources on total volatile fatty acid production and ammonia-N. Conclusion: It may be concluded that L. chinensis, M. malabathricum, L. speciosa, S. cumini, and T. chebula are having potent methane suppressing properties as observed in vitro in 24 h. These leaves could be supplemented in the animal diet for reducing methane emission; however, in vivo trials are warranted to confirm the methane inhibitory action and optimize the level of supplementation

Conclusions and researchable priorities

Given that the livestock production system is sensitive to climate change and at the same time itself a contributor to the phenomenon, climate change has the potential to be an increasingly formidable challenge to the development of the livestock sector in the world. This chapter provides the salient findings established by various researchers in their field of specialization and also elaborates on the future research priorities that are available before the researchers in the field of climate change and livestock production. In the changing climatic scenario, apart from high ambient temperature, air movement, solar radiation, wind speed, and relative humidity are other critical attributes of the climatic variables that hamper livestock production. The direct effects on livestock production are primarily mediated through increased temperature, altered photoperiod, and changes in rainfall pattern. The indirect effects on livestock production are mediated through sudden disease outbreaks, less feed and water availability, and low grazing lands. There are different adaptive mechanisms by which livestock respond to fluctuations of climatic changes including physiological, blood biochemical, neuroendocrine, cellular, and molecular mechanisms of adaptation, respectively. Globally, the livestock sector contributes 18 % of global GHG emissions. Hence, understanding of GHG emissions by sources and removal by sinks in animal agriculture is critical to take appropriate mitigation and adaptation strategies and to estimate and develop inventory of GHGs. The chapter also signifies that considerable research efforts are needed to modify the existing shelter design to make them more suitable for the current climate change scenario. The chapter also calls for multidisciplinary approach to develop suitable technological interventions to cope up to climate change for the ultimate benefit of livestock farmers who rely heavily on livestock resources for their livelihood security. If one attempts improving livestock production under the changing climate condition, research efforts are needed to develop strategies encompassing adaptation, mitigation, and amelioration strategies simultaneously, apart from strengthening the existing extension system