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Guidance of the SPECIAL FOCUS ‘Strengthen the Application of Environmental Physiology Research and Support the Development of Healthy Livestock and Poultry Farming’     ZHANG HongFu Scientia Agricultura Sinica   2018,51(16 ):3159 -3161. DOI:10.3864/j.issn.0578-1752.2018.16.011 Abstract  （205） HTML （9） PDF（pc） （260KB）（117） Save Reference丨 Related Articles丨 Metrics

Effect of Heat Stress on Lactation Performance in Dairy Cows     HAN JiaLiang, LIU JianXin, LIU HongYun Scientia Agricultura Sinica   2018,51(16 ):3162 -3170. DOI:10.3864/j.issn.0578-1752.2018.16.012 Abstract  （406） HTML （29） PDF（pc） （385KB）（254） Save With the steady aggravation of global warming, dairy cows face increasing heat stress, which results increasing economic loss to the dairy industry. Heat stress occurs when cows are exposed to extreme heat and cannot maintain their core temperature. Under hot temperature environment, dairy cattle is characterized by increased respiration, heart rate, and rectal temperature and decreased feed intake, which have a negative impact on endocrine system and immune system and seriously reduce milk performance of dairy cows. Previous studies of heat stress in dairy cows focused on its effects on productive performance, especially to alleviate the effect of heat stress by functional feed additives, but the specific mechanism of heat stress is not clear. This paper summarizes the widespread impact of heat stress on milk production and quality of dairy cows in different regions, and introduces the known mechanisms of heat stress from aspects of energy metabolism, endocrine, oxidative stress, apoptosis and autophagy. In the aspect of energy metabolism, heat stress induces a negative energy balance in cows by reducing food intake and inducing disorder in lipid breakdown and energy metabolism; In terms of endocrine system, heat stress affects the hypothalamic-pituitary-adrenal axis / thyroid axis / gonadal axis / growth axis of dairy cows and results in hormonal changes. In oxidative stress, heat stress affects the ROS levels in vivo and activates related defense signal pathways. In the aspect of apoptosis and autophagy, heat stress contributes to the damage of mammary epithelial cells by the expression of apoptosis-related genes and by excessive autophagy. The paper put forward that in the foreseeable future, heat stress will be a major challenge for the dairy industry. It is necessary to establish cows heat stress models to comprehensively investigate the basic mechanisms of heat stress in dairy cows using advanced cellular and molecular techniques. In addition, efforts should be placed to develop new interventions to reduce the damage of hear stress to dairy cows. Reference丨 Related Articles丨 Metrics

Effects of Ambient Temperature on Production Performance of Sows and Regulatory Techniques     ZENG YaQiong, WANG Hao, LIU ZuoHua, LI Shuang, PU ShiHua, LONG DingBiao Scientia Agricultura Sinica   2018,51(16 ):3171 -3180. DOI:10.3864/j.issn.0578-1752.2018.16.013 Abstract  （431） HTML （15） PDF（pc） （494KB）（342） Save The pig industry is one of the mainstay industries of China's agriculture and rural economy. As the core component of pig farms, production performance of sows are the key factors for determining the economic benefits of pig farms. China is the largest pig breeding country in the world, and the number of breeding sows and commercial pigs are more than 50% of the world’s total. However, compared with developed countries, sows feeding management level is low in our country, and there is still a large gap in production performance. The performance of sows in practical production is affected by many factors, including nutrient intake, body characteristics, feeding environment, parity of sows, etc. Thermal environment is one of the major factors affecting the health and production performance of sows. The warm environment consists of temperature, relative humidity, air flow, radiation, and heat transfer. These factors work together on the animal to make them feel cold or hot and comfortable or not. The suitable thermal environment is conducive to ensuring the sows’ health and improving their production performance. Conversely, the unsuitable warm environment will cause heat stress in sows, destroy the body heat balance, and even lead production stop, make the body enters a pathological state, cause illness and ultimately death. Therefore, mastering the warm environment requirements of sows and adopting effective control measures are essential to improve the performance of sows and the economic benefits of pig farms. This paper reviewed the effects of warm environment on sows and the corresponding regulation techniques, aiming to provide theoretical basis and technical support for the regulation of thermal environment in pig production and management in China. (1) The effects of the warm environment on the sow are mainly reflected in changes of behavior, physiology and production performance. In terms of behavior, sows will be thermally adjusted by changing the behavioral posture, such as increasing the lying time, reducing the standing and prone time in hot environment. Because the contact area of the sows' body surface with the ground is larger when the side is lying, and the heat dissipation of the body can be increased, but frequent changes in sows’ posture will increase the piglet death rate. In the aspect of physiology, sows will reduce metabolic heat production and increase heat dissipation by reducing feed intake, increasing respiration rate and skin blood flow during heat stress, while promoting the adrenocorticotropic hormone and cortisol in the blood of sows, thyroxine dropped and insulin sensitivity increased. These physiological changes will destroy the endocrine and energy balance of the sow, leading to early embryo death, miscarriage and milk production reduction. In terms of production performance, heat stress adversely affects the performance of sow estrus interval, litter size and lactation. Heat stress mainly affects the re-service rate and litter size at pre-pregnancy and in late pregnancy mainly affects the number of live births and stillbirths. After parturition, heat stress mainly affects the survival rate of piglets. High ambient temperature adversely affects the performance of weaned piglets by affecting the lactation of sows, and heat stress can delay the weaning-to-estrus interval by affecting the feed intake, weight loss and hormone secretion of sows. (2) Thermal environment control technology of sows mainly includes overall cooling and partial cooling of the pig house. The Pad and Fan evaporative cooling system is the representative of the overall cooling of pig house. In the system, the negative pressure inside the house is caused by the exhaust of the fan, forcing the unsaturated air outside the house to flow through the wet porous curtain, causing the evaporation of water to absorb a large amount of latent heat, thereby reducing the temperature inside pig house. The system has the advantages of simplicity and cost-effectiveness. The local cooling of the pig house is mainly for the temperature control of the lying area floor, pig pens on both sides and upper part of the pig pens. The main methods include air duct evaporative cooling, cold water cover cooling, floor cooling, etc. These methods have the advantages of obvious cooling effect and energy saving. Reference丨 Related Articles丨 Metrics

Regulation of Biological Clock in Ovulation-Laying of Laying Hens     WANG XiaoJuan, LIU Lei, JIAO HongChao, ZHAO JingPeng, LIN Hai Scientia Agricultura Sinica   2018,51(16 ):3181 -3190. DOI:10.3864/j.issn.0578-1752.2018.16.014 Abstract  （371） HTML （12） PDF（pc） （413KB）（473） Save The endogenous circadian rhythm enables the organisms to predict the changes of environmental cycle, which maintains consistency between body metabolism and the external environment. During the maturation of follicular, ovulation, and the formation of egg in birds, the coincidence of the different physiological processes in time shows the unity of the body itself and the coordination between the body and the environment. Biological clock participates in a series of behavior and physiological processes such as nutrition intake, the production of endocrine hormones and energy metabolism. In the present review, the role of biological clock in neuroendocrine, energy intake and energy metabolism has been discussed, from the points of light factor and nutrition factor, to reveal the potential regulating mechanism underlying ovulation and egg laying of hens. (1) Light signal acts on hypothalamic- pituitary-gonadal axis (HPG) by regulating the biological clock to influence reproductive activities. Under the stimulation of light, the central clocks in suprachiasmatic nucleus (SCN) and pineal act on hypothalamus, and make it to release gonadotropin releasing hormone (GnRH) and gonadotropin inhibitory hormones (GnIH) periodically. GnRH and GnIH then act on pituitary, and make it to release gonadotropin hormone, that is luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Periphery clocks in ovary receive the central synchronization signal to maintain the biological rhythm, thereby regulating the maturation of follicles and ovulation. (2) In addition to being regulated by the neuroendocrine system of HPG axis, the ovulation-egg production process of laying hens is also affected by the body's energy metabolism. The central and peripheral clock genes regulate the appetite regulation system and thus affect energy intake; Biological clock can regulate the expression of key enzymes in the process of metabolism, integrate the nuclear receptors and nutrition signaling proteins, regulate metabolism sensors and metabolites, affect gut microbes to regulate energy metabolism, and affect the synthesis, transport and deposition of yolk precursor; Melatonin secreted by bird's pineal can regulate calcium metabolism rhythmically by mediating the secretion of calcitonin, parathyroid hormone (PTH) and estrogen, and influence the formation of egg shell. The time and the behavior of energy intake, the body energy metabolism and energy status can also modulate biological clock, through some appetite regulation and energy metabolism related cytokines such as AMP-activated protein kinase (AMPK), and peroxisome proliferator-activated receptors α (PPARα). There are interactions between nutrient, biological clock and energy metabolism, which accommodate organisms with the surrounding and optimize the energy utilization. Therefore, by adjusting the time of eating and the composition of feed (such as the energy level of feed and calcium level), energy metabolism can be changed to regulate the function of the biological clock. In conclusion, it will provide a new perspective for researching regulation mechanism of egg laying, if we make an integrated study on environment factor (light management) and nutrition (feeding time and feed formula) in which biological clock linked external factors and internal energy metabolism, that is, biological clock can both response to environmental stimuli, and regulate the body's energy metabolism process, to optimize the various physiological functions. Reference丨 Related Articles丨 Metrics

Research Progress on the Regulatory Mechanism of Lighting Schedule Affecting the Reproduction Performance of Chickens     SHI Lei, LI YunLei, SUN YanYan, CHEN JiLan Scientia Agricultura Sinica   2018,51(16 ):3191 -3200. DOI:10.3864/j.issn.0578-1752.2018.16.015 Abstract  （338） HTML （16） PDF（pc） （395KB）（303） Save Light is an important environmental factor for the organism. Artificial lighting has been widely utilized in modern poultry production. The poultry is light-sensitive. Light regulates their growth, production, and reproduction, and therefore affects the production efficiency. Light has now been another important environmental factor for poultry industry besides temperature, humidity, and ventilation. As a classical model animal, the studies of the effects of light on chicken reproductive physiology and the underlying mechanism would be of scientific significance. The photoreception of poultry and the effects of light schedule on chicken sexual maturity and reproduction were summarized in this review. The research progress on ahemeral lighting schedule, photorefractory, and light management during eggs incubation was also included. This review aimed at providing better understanding the effect of light schedule on poultry reproduction and the underlying mechanism. Perceiving the lighting by photoreceptors including eyes (retina), the deep brain tissue, and the pineal gland, the poultry transfers the lighting information to biological signals and affect the neuroendocrine system, especially the hypothalamic-pituitary-gonadal axis to affect the growth and reproduction. The gonad of birds develops rapidly and shows sensibility for the lighting length during rearing period. Lighting length of too short or long may impede the development or accelerate sexual maturity. The studies showed that a constant light of 8 or 9 h might assure the body condition and potential of reproduction performance. The lighting schedule parameters during the laying period of poultry includes photostimulation and lighting length. Photostimulation must be applied at a right age to assure the concurrent sexual maturity. Because of limited researches in yellow-feathered laying hens, most often they follow the photostimulation strategy of high-producing hens or with slight delay of photostimulation age. Lighting length is also critical for the reproduction performance. Laying hens (breeders) need long lighting period to keep productive during the laying period. There are, however, many differences between broiler breeders and layer hens (breeders), such as body condition, feeding and physiological characters, and photo factory. Broiler breeders are suggested to have shorter lighting length (14 or 15 h) than laying hens (breeders) (16 or 17 h). The advanced sexual maturity is meaningful for poultry industry. With the development of semen dilution and preservation, and alternate use of male breeders, more and more studies are focusing on the effects of light on the reproduction of male breeders. Housing the male breeder underling the same lighting length as females after sexual maturity may reduce semen quality. It is therefore necessary to provide different lighting schedule management for male and female if condition permits. Different from the normal 24-h lighting schedule, ahemeral lighting schedule can increase egg weight, but may lessen production. It is not widely used in practice due to European standards for animal welfare regulations and its inconsistency with the regular schedule of the employee. The study of ahemeral lighting schedule is, however, still important for understanding of the biorhythm of poultry. Reference丨 Related Articles丨 Metrics

Research Review on CO2 Production in Pig House     ZHOU Dan, DIAO YaPing, GAO Yun, HUANG FeiRuo, LI Ji, WANG JiaoJiao, LEI MingGang, LI Xuan Scientia Agricultura Sinica   2018,51(16 ):3201 -3213. DOI:10.3864/j.issn.0578-1752.2018.16.016 Abstract  （334） HTML （11） PDF（pc） （468KB）（666） Save CO2 is a major part of the atmosphere and is a member of greenhouse gases. It is not just a major contributor to global warming. And it is one of the harmful gases that cannot be ignored in the pigpen. In recent years, with the development of scale and intensive pig housing, the research on the factors affecting the temperature, humidity, NH3, H2S and CO2 in the piggery is increasing. CO2 plays an important role in the environment of piggery and is an important parameter to evaluate the environmental quality of piggery. The effective management of CO2 in piggery can improve the management level of piggery breeding and maximize economic benefits. This article first expounds the main source of CO2 emissions of piggery pig breath, waste discharge, heating equipment, analyzes the CO2 emissions are mainly affected by the external environment, the number and type, volume of piggery and pig manure storage time and other factors. The CO2 emissions of live pigs in different growth stages of weaning, breeding, fattening and sows were compared and analyzed under conditions of leaky floor, partially leaky floor, straw mat and wood chip floor. Discusses the inner generated by different concentration of CO2 in breeding, pig physiological behavior, the influence of the pork quality, according to CIGR data, draw corral CO2 concentration limit was 0.3%, the largest of the CO2 concentration limit of 0.5%, In piggery CO2 content is too high, the content of oxygen deficiency, for a long time can cause a chronic hypoxic pigs, depression, loss of appetite, weight gain, slow, weak, susceptible to infectious diseases, the problem such as production levels drop, serious when, after the death of a pig appeared ecchymosis, slaughter appear blood, flesh PH, conductivity, moisture content decreased, affect significantly the quality of pork. Secondly, the method of CO2 content monitoring in the shed and the research progress at home and abroad are summarized. Inductive analysis of the strength of CO2 and ventilation, ventilation rate, the relationship between the air inlet position, in detail elaborated the cesspit ventilation system by changing the intensity of ventilation, air inlet location, the size of the floor openings, can effectively reduce CO2 in the house. Calculate the ventilation rate in piggery of there are three kinds of methods, one is to use the animals themselves to calculate temperature balance, 2 it is used to measure the air humidity, three is the CO2 balance equation method, calculate the ventilation rate of the current mainstream approach is the use of CO2 from the air balance characteristics, monitoring CO2 concentration, according to the concentration of CO2 and ventilation rate equation, the relationship between the size of the calculation of ventilation rate. Finally, according to the actual research situation, the future research direction and development trend of CO2 content in piggery are prospected. Reference丨 Related Articles丨 Metrics

Research Progress on Characteristics of Particulate Matter in Livestock Houses and Its Harmful Effects on Respiratory Tract Health of Livestock and Poultry     DAI PengYuan, SHEN Dan, TANG Qian, LI YanSen, LI ChunMei Scientia Agricultura Sinica   2018,51(16 ):3214 -3225. DOI:10.3864/j.issn.0578-1752.2018.16.017 Abstract  （275） HTML （21） PDF（pc） （2071KB）（292） Save With the improvement of livestock and poultry intensive breeding, high density breeding livestock and poultry farms air quality problem becomes increasingly prominent. The livestock production process can generate a large number of PM, which has become an important source of fine particulate PM2.5 (aerodynamic diameter ≤ 2.5 μm) and PM10 (aerodynamic diameter ≤ 10 μm ) in atmosphere, affecting the air quality and the health of livestock seriously. PM in livestock houses is mainly organic and mainly from feed, feces, feathers, dander, containing C, H, O, N, S, Ca, Na, Mg, Al, K, and other elements; the surface of PM also adheres to bacteria, fungi, viruses, endotoxins, ammonia gas, hydrogen sulfide and other harmful substances. It was found that PM concentration in chicken house was higher than that in pig house; PM concentration in livestock houses was positively correlated with the age and activity of animals; PM concentration in winter was higher than that in summer. However, there is a lack of standardized equipment and standard methods to measure PM concentration and emission levels in different types of livestock and poultry houses. PM components in livestock houses are complex and have strong biological effects, which seriously hazard the health and animal production. High PM concentration in livestock houses affects respiratory health mainly in the following three forms: the directly stimulation of PM to respiratory tract which reduces the immune resistance of the body to respiratory diseases; the stimulation of various compounds attached to PM surface; the stimulation of pathogenic and non-pathogenic microorganisms on PM surfaces. At present, studies on the mechanism of PM on respiratory health hazards mainly focus on the inflammatory effect of PM on respiratory tract Studies showed that, PM could induce cells to release inflammatory factors and cause lung inflammation reaction through the proinflammatory factor produced by alveolar macrophages stimulated by PM. In addition, PM2.5 upregulated the expression of nuclear transcription factor κB (NFκB) and transcription activator AP-1 by mitogen-activated protein kinase (MAPKs) which was activated by oxidative stress. PM2.5 could also identify the toll-like receptor 2 and 4 by activating the mode of activation, and activate the NFκB signaling pathway, leading to the occurrence of inflammation. Studies have also found that the cell autophagy and nuclear factor related factor - 2 (nuclear factor E2 - related factor 2, Nrf2) related signaling pathways would be activated during the process of inflammation induced by PM2.5, which provided the targets for treatment of cell damage induced by PM2.5. Although there were more study on mechanism of hazard of PM to the health of respiratory tract, the PM composition was complicated, and in a constantly changing, so the PM induced respiratory damage mechanism was very complex and need further study. A large number of PM released in the process of livestock production seriously affects the environmental air quality and the health of livestock, and the extent of PM's harm to the environment and the health of livestock was closely related to its composition and concentration. Therefore, a proper understanding of PM morphology, size, composition, concentration level and emission influencing factors of animal house is of great significance to the determination of PM source and hazard caused by PM toxicity. In this paper, the source, chemical composition, concentration, discharge, influence factors, and the effects on respiratory function of PM from animal house are summarized, and offer a base for evaluating the effect of PM on healthy production of livestock and poultry. Reference丨 Related Articles丨 Metrics

Review of Environmental Parameters in Pig House     GAO Hang, YUAN XiongKun, JIANG LiLi, WANG JunJun, ZANG JianJun Scientia Agricultura Sinica   2018,51(16 ):3226 -3236. DOI:10.3864/j.issn.0578-1752.2018.16.018 Abstract  （401） HTML （74） PDF（pc） （493KB）（603） Save The environment is the most important to protect the health of livestock and poultry breeding. According to the data published in the "2016 Statistical Communique on National Economic and Social Development", the total output of meat in 2016 was 85.4 million tons, including 52.99 million tons pork and 435.04 million pigs, and were kept at the end of the year. With the development of large-scale and welfare pig rising of pig industry in China, China, as a traditional pig production and consumption of pork in the current, has a high yield of pig breeds and high-quality feed, and more and more attention has been paid to the effect of microclimate environment on the health of pigs. The developed countries, such as Europe and the United States, attach great importance to the optimal control and research on the environmental management of livestock and continuously develop new technologies to ensure the healthy and sustainable development of livestock husbandry and aquaculture. From the 60s of the last century, the effects of temperature, humidity, harmful gases and stocking density on feed performance and livestock production performance were studied, and the requirements and thresholds for environmental parameters such as temperature, humidity and stocking density were proposed. However, the ecological climatic zone in our country is complex, livestock breeding facilities are poor, the technology lacks standards, and the integration of factors of production lacks a unified environmental basis. When the swine house environmental is terrible, it will impact on health and restrict the growth performance of pigs. Based on the existing environmental parameters of pigs in our country, combined with the existing relevant environmental parameters and experimental studies both our country and other countries, this paper analyzed the effects of temperature, humidity, concentration of harmful gases and stocking density on the growth of pigs, so as to provide a reference and basis for the research, renewal and application of pig comfort environmental parameters in China. Reference丨 Related Articles丨 Metrics