S. M. K. Naqvi

Environmental stress and amelioration in livestock production

Introduction.- Factors influencing livestock productivity.- Heat stress impact on livestock production.- Walking stress influence on livestock production.- Environmental stresses and livestock reproduction.- Concept of multiple stresses and its significance on livestock productivity.- Ameliorative measures to counteract environmental stresses.- Nutritional manipulations to optimize productivity during environmental stresses in livestock.- Role of pineal gland in relieving environmental stress.- Basic principles involved in adaption of livestock to climate change.- Neuroendocrine regulations of adaptive mechanisms in livestock.- Molecular mechanisms of livestock adaptation.- Genetic adaptability of livestock to environmental stresses.- Genes involved in the thermal tolerance of livestock.- Impact of climate change on livestock production.- Global climate changes: Enteric methane reduction strategies in livestock.- Conclusions and Researchable Priorities.

Sequence analysis and identification of new variations in the coding sequence of melatonin receptor gene (MTNR1A) of Indian Chokla sheep breed

Melatonin receptor 1A gene is the prime receptor mediating the effect of melatonin at the neuroendocrine level for control of seasonal reproduction in sheep. The aims of this study were to examine the polymorphism pattern of coding sequence of MTNR1A gene in Chokla sheep, a breed of Indian arid tract and to identify new variations in relation to its aseasonal status. Genomic DNAs of 101 Chokla sheep were collected and an 824 bp coding sequence of Exon II was amplified. RFLP was performed with enzyme RsaI and MnlI to assess the presence of polymorphism at position C606T and G612A, respectively. Genotyping revealed significantly higher frequency of M and R alleles than m and r alleles. RR and MM were found to be dominantly present in the group of studied population. Cloning and sequencing of Exon II followed by mutation/polymorphism analysis revealed ten mutations of which three were non-synonymous mutations (G706A, C893A, G931C). G706A leads to substitution of valine by isoleucine Val125I (U14109) in the fifth transmembrane domain. C893A leads to substitution of alanine by aspartic acid in the third extracellular loop. G931C mutation brings about substitution of amino acid alanine by proline in the seventh transmembrane helix, can affect the conformational stability of the molecule. Polyphen-2 analysis revealed that the polymorphism at position 931 is potentially damaging while the mutations at positions 706 and 893 were benign. It is concluded that G931C mutation of MTNR 1A gene, may explain, in part, the importance of melatonin structure integrity in influencing seasonality in sheep.

Walking Stress Influence on Livestock Production

The food available to grazing animals, particularly during the dry season, in the tropics, is often of very low quality and, in addition, is frequently available at low densities per unit area. Grazing ruminants attempt to adapt to these adverse conditions by increasing the time for which they graze each day and also by dispersing more widely. However, the time for which animals can graze may be limited by solar radiation and fly irritation during the day. Depending on management conditions, livestock are required to walk long distances. When walking is restricted (1–3 km/day), animal performance is generally not reduced. However, under certain conditions (scarce or hilly pasture) the distances walked by livestock can be substantially greater. Unusual physical activity is considered a stress factor in all species since it induces neuroendocrine and metabolic changes which in turn alter the physiological responses, endocrine and enzymes’ release status and productivity in animals. In addition, there are both breed and interspecies differences in locomotory efficiency as a result of morphological, physiological and behavioural adaptations in livestock. The significant changes in physiological responses, adrenal and thyroid hormone concentrations after subjecting the livestock species to walking stress shows that they are capable to adapt to long-distance walking and adrenal and thyroid gland hormones play a significant role in such adaptation. Though, while trying to adapt to long-distance walking scenario in search of food, animals compromise their productive performance. This is reflected as significant reduction in growth, milk and reproductive performance of different livestock species. The reason for this low production could be a major proportion of the energy is shifted to combating the walking stress as any counter measures need energy source for its implementation. The repercussions of walking or work on production performances have been studied by various researchers and reported that livestock energy requirement increases significantly during walking exercise. Further, most of the increase in energy expenditure of physical activity results from grazing and locomotion costs. The energy expenditure of locomotion during grazing contributes significantly to the energy requirement of animals in free-living conditions and must be included for accurate evaluation of the energy needs of the grazing animal.

Assessment of Genetic Variability in the Coding Sequence of Melatonin Receptor Gene (MTNR1A) in Tropical Arid Sheep Breeds of India.

Seasonal behaviour in sheep, which varies in tropical and temperate environmental conditions, is a matter of study, because it can provide a clue to address the problem of seasonality in sheep. Melatonin receptor is the membrane-bound G-coupled receptor, sensing the message of photoperiodic cues thorough melatonin. Restriction fragment length polymorphism (RFLP) studies were carried out to assess the variability of gene at G612A and C606T SNPs in MTNR1A gene, which have been studied to be markers for out-of-season breeding. Allelic frequency distribution corresponded to higher frequency of GG and CC genotype, in tropical arid sheep breed in comparison with temperate region sheep breed. PCR amplification of MTNR1A gene of 30 animals was performed and single nucleotide polymorphisms (SNPs) identification was carried out using Lasergene software. Seven SNPs/mutations were identified, but most of them were synonymous, except the one G706A, leading to substitution of valine by isoleucine. Polyphen-2 analysis of G706A mutation revealed that it is a benign mutation. Two important SNPs C426T and G555A, which were identified in temperate sheep breeds, could not be traced in Magra and Marwari breeds of sheep. Thus, the Magra and Marwari breeds of tropical, arid region demonstrated the presence of both polymorphic SNPs markers G612A and C606T, associated with out-of-season breeding. GG and CC genotypes were having a higher prevalence in the studied population.

Livestock and Climate Change: Mitigation Strategies to Reduce Methane Production

Global warming refers to a significant rise in the planets temperature making it uninhabitable. It happens thus: the earth is warmed by energy from the sun. In order to maintain its temperature, the earth must radiate some of that energy back into the atmosphere. However, certain atmospheric gases form a blanket around the earth, allowing solar radiation to penetrate, but preventing it from escaping. The more these green house gases, the hotter the earth (Sarmah, 2010).

Environmental Stresses and Livestock Reproduction

Reproductive fitness may be regarded as the most important criteria for studying or evaluating animal adaptation. Body systems activated by stress are considered to influence reproduction by altering the activities of the hypothalamus, pituitary gland, or gonads. Activation of stress pathways may directly affect the activity of Gonadotropin-releasing hormone (GnRH) neurons within the hypothalamus or higher neural centers which in turn affects the synthesis or secretion of GnRH into the hypophysial portal blood. It is also possible that stress directly influences the responsiveness of gonadotrophin cells in the anterior pituitary gland via the action of GnRH. A further potential action of stress is to alter the feedback actions of sex steroids in the hypothalamus or pituitary and inhibin in the anterior pituitary gland. Reproduction processes in animals may be impacted during heat exposure and glucocorticoids are paramount in mediating the inhibitory effects of stress on reproduction. Glucocorticoids are capable of enhancing the negative feedback effects of estradiol and reducing the stimulation of GnRH receptor expression by estrogen. Glucocorticoids may also exert direct inhibitory effects on gonadal steroid secretion and sensitivity of target tissues to sex steroids. Heat stress (HS) influences estrous incidences and embryo production. The birth weights of lambs of heat stressed ewes are generally lower than the unstressed animals. This could be attributed to the fact that HS may cause a temporal impairment of placental size and function, resulting in a transient reduction in fetal growth rate. Secretion of the hormones regulating reproductive tract function may also be altered by HS. Further, HS can inhibit 3-beta-hydroxysteroid dehydrogenase (3β HSD) thereby minimizing progesterone secretion from luteal cells. Aromatase is an enzyme that converts androgens into estrogens and is present in the granulosa cells. By inhibiting the expression of this enzyme, HS may induce follicular atresia and consequently anestrus. Effects of steroid hormones on reproductive tract tissue could be reduced during exposure to HS due to increased synthesis of heat shock proteins (HSPs)—HSP 70 and HSP 90. Increased synthesis of HSP might alter assembly, transport, or binding activities of steroid receptors. Further, increased magnitude of these stresses will increase secretion of prostaglandin and reduce the secretion of interferon tau which affects the maternal recognition of pregnancy. In male, HS adversely affects spermatogenesis by inhibiting the proliferation of spermatocytes. This chapter will address the effect of environmental stresses on livestock reproduction.

Climate Change and Water Availability for Livestock: Impact on Both Quality and Quantity

Water is an essential production factor in agriculture, both for crops and for livestock. Climate change will have a significant impact on agriculture in terms of affecting both water quantity and quality. It is known that changing climate will affect the water resource availability and global hydrological cycle. Livestock particularly in arid and semiarid region are mostly reared under extensive or traditional pastoral farming systems. The animals have different water requirements in different ambient temperatures. The requirement of water varies breed to breed according to their adaptability in a particular region and ambient temperature. Livestock of arid and semiarid region face the problem of water scarcity in most of the time of the year. So the animals need to take adaptive mechanism to overcome the water deprivation in different physiological stages. The animals exhibit several adaptive mechanisms to cope up to the less availability of water. These mechanisms include reduced plasma and urine volume, reduced faecal moisture, reduced body weight and reduced feed intake. The blood biochemical changes include increased haemoglobin, increased blood cholesterol and urea concentration, reduced protein concentration and increased sodium and potassium concentration. The endocrine changes include increased cortisol and reduced insulin, T3, T4 and leptin concentration in livestock. In addition, water deprivation in rumen also plays an important role in maintaining homeostasis in adapted animals. An adequate and safe water supply is essential for the normal and healthy production of livestock. Generally, surface or groundwater is supplied to the animals. This water source should be protected from microorganisms, chemicals and other pollutant contaminations. Keeping in view the adverse water scarcity predicted in the future, strategies have to be developed to improve water-use efficiency and conservation for diversified production system in different locations. More research is needed into water resources’ vulnerability to climate change and in order to support the development of adaptive strategies for agriculture.

Effect of Controlled and Uncontrolled Rate of Cooling, Prior to Controlled Rate of Freezing, on Motion Characteristics and Acrosomal Integrity of Cryopreserved Ram Spermatozoa

A programmable cell freezer provides ideal cryobiological conditions for controlled-rate cooling and freezing of ram spermatozoa. The purpose of this study was to investigate the effects of controlled (Group 1) and uncontrolled (Group 2) cooling conditions prior to programmable freezing of ram semen on post-thaw sperm motion characteristics and acrosomal integrity of ram spermatozoa. Semen samples of good initial motility obtained from adult Malpura rams were pooled, diluted to 1 × 10(9) spermatozoa per milliliter with Egg yolk-TEST-glycerol extender, and packaged in 0.25 mL straws. Straws representing Group 1 were cooled in a programmable cell freezer from 25°C to 5°C at the rate of -0.15°C per minute followed by a holding time of 2 h for equilibration, while straws of Group 2 were allowed to cool slowly up to 5°C and equilibrate for 2 h in the cold cabinet. After equilibration, straws of Group 2 were also loaded in the cell freezer for freezing straws of both the treatment groups simultaneously from 5°C to -125°C at the rate of -25°C per minute. Thawing of straws was done at 50°C for 10 s and the quality of frozen-thawed spermatozoa was objectively assessed by using sperm motility analyzer. Thawed samples were also evaluated for acrosomal integrity after staining the dried semen smears with Giemsa stain. The average post-thaw motility of straws was significantly higher (P < 0.05) in samples frozen after controlled cooling, compared with samples frozen after uncontrolled rate of cooling. The percent of spermatozoa with normal acrosome was also significantly (P < 0.05) higher in Group 1, compared to Group 2. The results indicate that controlled-rate cooling has a significant effect on post-thaw motility and acrosomal integrity of frozen-thawed ram spermatozoa, compared to uncontrolled-rate cooling prior to programmable freezing.

Physiological rhythmicity in Malpura ewes to adapt to cold stress in a semi-arid tropical environment

Abstract A study was conducted to assess the rhythmic pattern of physiological parameter in Malpura ewes to adapt to cold stress in a semi-arid tropical environment. Eighteen adult Malpura ewes were selected for the present study. These ewes were randomly allocated into two groups: GI (Open shed; n=9) and GII (Protected; n=9). The study was conducted for a period of 30 days during the peak winter season (December 2011) during which the animals were stall fed. Blood samples were collected at fortnightly interval. The growth, physiological response, blood biochemical response and endocrine response parameters were studied. The results reveal that cold stress had significant negative influence on all the parameters studied in the ewes. In conclusion, it can be said that cold stress had significant influence on the biological functions in the ewes that would result in the impairment of their production and reproductive efficiency as well. The study also indicates the relevance of provision of appropriate protective measures to foster cold during the extreme winter months in the arid and semi-arid tropical areas.

Sheep Production Adapting to Climate Change

This book presents a compilation of the latest findings from reputed researchers around the globe, covering in detail climate change and its effects on sheep production. In the current global climate change scenario, information related to its impact on livestock agriculture is lacking. The negative impacts of climate change are already being felt by all livestock species. Further, the mitigation and amelioration strategies that are applicable for one species may not hold true for another. As such, concerted research efforts are needed to identify species-specific strategies for mitigation and adaptation. With that goal in mind, this book is the first of its kind to gather comprehensive information pertaining to the impact of climate change on various aspects of sheep production. It also sheds light on the role of sheep with regard to the global greenhouse gas pool. The book highlights the status quo of sheep production from climate change perspectives and projects the significance of adapting future sheep production to the challenges posed by climate change. It addresses in detail the various adaptations, methane mitigation and amelioration strategies needed to sustain sheep production in the future. In addition, the book presents development plans and policies that will allow the sheep industry to cope with current climate changes and strategies that will lessen future impacts. Bringing together essential information prepared by world-class researchers hailing from different agro-ecological zones, this book offers a unique resource for all researchers, teachers and students associated with sustaining the sheep production in the face of global change.