Discussion of a biometrical model for the evaluation of feeding, age, and animal effects on transport properties of small intestinal mucosa

This paper is concerned with the question in which ways study results can depend on the choice of the statistical model and factors included in this model. This is shown using example data of a study dealing with the effects of an Enterococcus faecium as probiotic in the diet of pigs. We focused on the effects on transport properties of pig jejunum. The experimental design was the following: the sows and piglets were randomly assigned to two different feeding groups. The control group was fed a conventional diet and the experimental group was additionally supplemented with a probiotic preparation of Enterococcus faecium NCIMB 10415. The animals were divided into four age groups. Two samples of five animals of each feeding and age group were taken and mounted into conventional Ussing chambers. Glucose transport rates were measured by changes in short-circuit current (Isc) of the pig jejunum epithelium. The appropriate reference base for evaluation of effects of feeding or age on Isc is the variation between animals which are submitted to identical conditions relating to these factors. To refer explicitly to this variation a random animal effect has to be included in the statistical model of variance analysis. Otherwise the variation between animals could be underestimated. With the example data set conclusions for the factor "feeding" would be different depending on whether a random animal effect is included in the model or not.     

菟丝子总黄酮对生殖内分泌调节的研究进展

近年来,菟丝子在临床上经常用于治疗生殖内分泌类疾病,且作用效果显著。菟丝子是旋花科植物,具有毒副作用小、无耐药性、富含多种营养物质、成本低廉等优点,是纯天然的药用植物。菟丝子总黄酮是菟丝子中最有效的成分,具有止泻、滋补肝肾、益精壮阳和安胎等功效,不仅对雌雄动物生殖内分泌活动有调节作用,还对免疫、心脑血管等多个系统具有药理作用。动物的生殖内分泌活动主要由下丘脑-垂体-性腺轴调控,包括生殖激素的分泌以及精子的发生、卵泡的发育,对动物生殖繁育起着重要作用。绝大多数动物的生殖内分泌疾病都与下丘脑-垂体-性腺轴所调节的生殖激素以及生殖器官的发育状态有关,生殖激素可以通过直接或间接作用引起下丘脑-垂体-性腺轴功能性障碍疾病。鉴于目前经济动物禁用激素类药物,因此迫切需要研究安全有效低毒的中草药的作用及其机理,为其广泛应用奠定基础。文章介绍了菟丝子总黄酮主要的药理作用,并详细阐述了菟丝子总黄酮对下丘脑-垂体-性腺轴不同级内分泌活动的调控作用,为今后进一步研究菟丝子总黄酮对下丘脑-垂体-性腺轴调控的作用靶点和作用机理提供参考。     

Bmp/Smad信号通路及其在哺乳动物卵巢发育中的作用

开展绵羊多羔性状基因的研究对于揭示其分子调控机制和提高绵羊繁殖力具有重要意义。骨形态发生蛋白(BMPs)为转化生长因子-β(TGF-β)超家族成员,与哺乳动物繁殖活动密切相关。研究表明,BMPs可促使原始卵泡向次级卵泡转化,对哺乳动物卵巢颗粒细胞增殖、生殖激素的合成和分泌以及卵母细胞成熟和排卵等方面起重要调节作用,而BMPs发挥功能主要依赖于经典的Bmp/Smad信号通路。本文就Bmp/Smad信号通路成员的表达、对早期胚胎发育的影响以及在哺乳动物卵巢发育中的作用等方面的研究进行总结,以期为进一步研究BMPs及其信号通路的调控机制提供参考。     

A model for assessing the impact of behavioral stress on domestic animals

Animal scientists need a reliable measure of behavioral stress in domestic animals if they are going to be able to assess the stress of various management practices and to answer public concern about the well-being of animals used in agriculture. Popular measures of stress, alterations in behavior or changes in hormone secretion, are not adequate because of a failure to establish any direct correlation between changes in these characteristics with adverse effects on animal well-being. Further complicating the use of these indicators of stress is the variation in their pattern of response to different kinds of stressors. Even the same stressor can elicit divergent responses in different animals because of inter-animal variation in the stress response. To address these problems, a model of animal stress is discussed and tested. From this model it is proposed that the best indicator of an animal suffering from stress is the development of a pre-pathological state; i.e., a stress-related change in biological function that threatens the animal's well-being. Examples of such pre-pathological states would be a suppression of the immune system, the loss of reproductive events critical for normal reproduction, or the development of behaviors that would lead to such undesirable acts as tail-biting or excessive fighting. Although determining the existence of such pre-pathological states is not convenient, their existence is currently the only defensible indicator of an animal suffering from behavioral stress.     

Research progress on the role of melatonin and its receptors in animal reproduction: A comprehensive review

Melatonin and its receptors play a crucial role in the regulation of the animal reproductive process, primarily in follicular development. However, the role that melatonin performs in regulating hormones related with reproduction remains unclear. Melatonin and its receptors are present both in female and male animals’ organs, such as ovaries, heart, brain and liver. Melatonin regulates ovarian actions and is a key mediator of reproductive actions. Melatonin has numerous effects on animal reproduction, such as protection of gametes and embryos, response to clock genes, immune‐neuroendocrine, reconciliation of seasonal variations in immune function, and silence or blockage of genes. The growth ratio of reproductive illnesses in animals has raised a remarkable concern for the government, animal caretakers and farm managers. In order to resolve this challenging issue, it is very necessary to conduct state‐of‐the‐art research on melatonin and its receptors because melatonin has considerable physiognomies. This review article presents a current contemporary research conducted by numerous researchers from the entire world on the role of melatonin and its receptors in animal reproduction, from the year 1985 to the year 2017. Furthermore, this review shows scientific research challenges related to melatonin receptors and their explanations based on the findings of 172 numerous research articles, and also represents significant proficiencies of melatonin in order to show enthusiastic study direction for animal reproduction researchers.     

Dietary protein and the reproductive performance of cows

Increasing a cow's intake of dietary protein intake can increase its milk production, but can also reduce its fertility. This paper reviews the effects of increasing dietary protein on the fertility of the dairy cow, and the mechanisms that may produce them. The effects vary widely, but all stages of the reproductive cycle from the return to cyclicity after parturition, to the survival of the embryo, may be affected. However, the underlying cause of the link between protein intake and fertility is unclear. Fertility could be reduced by a direct toxic effect of protein breakdown products, but alternatively the increased energy demand for their metabolism could be responsible. The effect of protein degradability is also uncertain. Excess rumen degradable protein is commonly associated with reduced fertility, but similar effects are produced by diets that contain excess rumen undegradable protein. Increasing the intake of protein of all degradabilities has significantly different effects on blood biochemistry than a reduction in the intake of energy, suggesting that not all the effects of protein are due to energy imbalance. The primary site of action of the effect is also unclear. Limited evidence suggests that it is localised to the reproductive system, but effects on the pituitary and hypothalamus, as well as the ovary and uterus, have all been postulated. It is also uncertain what toxic principle is involved. Ammonia, nitrate and urea have all been suggested, but there is no conclusive evidence. Although a high protein intake has been postulated to have an effect on fertility for over 30 years, the evidence remains inconclusive, and the aetiology and pathogenesis of the effect remain obscure.     

Oxidative Stress During Pregnancy In The Sheep

During physiological pregnancy, all tissues and, mostly, placenta and foetus require high amounts of oxygen. Reactive oxygen species (ROS), generated both by mother and foetus, are implicated in foetal growth because they promote replication, differentiation and maturation of cells and organs. Nevertheless, ROS excess, if not properly counterbalanced, may lead to an alteration in cell constituents, with harmful effects both on mother and foetus.ROS exert a biphasic effect because adequate ROS concentration is essential for embryo development, implant, foetal defence against uterine infections, steroidogenesis, pregnancy maintainance and partum. On the other hand, an uncontrolled ROS generation, beyond physiological antioxidant defences, may lead to embryo resorption, placental degeneration with subsequent alteration in maternal‐foetal exchanges, delay in foetal growth, pregnancy interruption, stillbirths. This review investigates the mechanisms underlying ROS generation and effects, throughout physiological and pathological pregnancy in sheep, with a look to antioxidants and their importance in such a critical phase of the reproductive cycle of the sheep.     

The crossbred sire: theory

Favorable effects of heterosis on performance of the crossbred market animal and the crossbred dam have been well documented and breeding plans have been developed to utilize these effects. However, a similar mandate for use of the crossbred sire does not exist. Given the common developmental factors involved in reproduction in both sexes, it appears likely that the same nonadditive effects that lead to improved reproductive fitness in the female would also have an effect in the male. Most studies that have evaluated heterotic effects in the male have observed heterosis for at least some components of male reproduction, but have been unable to document consistently favorable effects of the crossbred male on overall conception rate. This result may reflect the categorical nature of conception and possible limiting effects of the female on expression of male differences. Important effects of true paternal heterosis, parallel to maternal heterotic effects acting through the maternal environment provided by the dam, appear unlikely because of the less-intimate relationship between offspring and sire. However, if the relationship between underlying breeding value and realized phenotypic merit is not linear, substantial realized paternal heterosis may be observed due to optimization of gene frequencies through use of the crossbred male. This result is likely for categorical traits or traits with an intermediate optimum breeding value. At the production system level, the appropriate unit of evaluation is the cohort composed of a male and the set of females that are exposed to the male for breeding. At this level, potential advantages of the crossbred male may accrue due to both heterosis for male fertility and optimization of gene frequency.     

The impact of the phyto‐oestrogen genistein on swine granulosa cell function

Soya and soybean products used in swine feeding contain genistein, a non‐steroidal phyto‐oestrogen which has been demonstrated to influence endocrine functions. This observation leads us to design this study to evaluate the effect of genistein on swine granulosa cell steroidogenesis and proliferation. In the attempt to unravel the genistein signal transduction mechanisms, we verified the effect of lavendustin, a Tyrosine Kinase (TK) inhibitor, and the potential involvement of NO/cGMP pathway. Finally, as angiogenesis is essential for follicle development, we tested the effect of the phyto‐oestrogen on vascular endothelial growth factor production and on granulosa cell redox status, because free‐radical species modulate neovascularization. Our data provide evidence that genistein interferes with granulosa cell steroidogenesis while it does not modulate cell growth: this effect could be at least partially produced by inhibiting TK‐dependent signalling systems. On the contrary, NO/cGMP pathway or vascular endothelial growth factor production can be excluded as signalling mechanism involved in phyto‐oestrogen effects. Remarkably, genistein stimulates hydrogen peroxide production thus potentially inhibiting follicular angiogenesis. Collectively, these results suggest that genistein consumption could potentially negatively impact swine reproductive function.     

The effect of pseudorabies (Aujeszky''s) virus infection on young mature boars and boar fertility.

This study was designed to determine the effects of experimental inoculation with pseudorabies virus on the reproductive tracts of young adult boars. Pseudorabies virus was inoculated intranasally into 12 boars and intrapreputially into four boars. All animals seroconverted after nasal or preputial inoculation. Semen abnormalities were observed 21 days postinoculation with partial recovery by 50 days postinoculation. Virus was isolated from the preputial sheath of two intrapreputially inoculated boars 12 days postinoculation. It was concluded that pseudorabies virus infection can be established via preputial inoculation and that decreased spermatogenesis and infertility can result.     

Review: Fertility Factors in High Producing Dairy Cows—Which Ones Are Really Important?

Reproductive management in high producing dairy cows is difficult because many fertility factors determine success. These many factors do not exert themselves with the same influence on fertility. Further, the degree to which each factor can be controlled varies greatly. Organizing fertility factors into groups that reflect their control enables reproductive management teams to focus on the most important factors and to exert positive influence. Factors controlling fertility can be subdivided into three distinct groups that reflect the degree to which each can be controlled. These groups are fertility factors controlled by humans, those controlled by the reproductive system of the cow, and those factors natural (intrinsic) to any herd. The most control can be exerted by factors controlled by humans, and there can be intermediate influence on factors controlled by the reproductive system of the cow. Very little control can be exerted on fertility factors intrinsic to each herd. Management effort should be focused on those factors over which control can be exerted and where there is a high probability of success.     

The role of essential trace elements in embryonic and fetal development in livestock

This review addresses the concept that essential trace minerals play a vital role in many enzymatic and metabolic pathways that are critical for conceptus development during pregnancy in livestock species. The conceptus relies entirely on the maternal system for a sufficient supply of trace minerals and other nutrients needed for normal development. If this supply is inadequate, growth and/or health of the conceptus can be affected adversely, and many of these effects carry over into the neonatal period. Information, accumulated in our laboratory and presented herein, indicates that zinc, copper and manganese are among the trace minerals that have the greatest impact on reproduction. For example, levels of zinc, copper and manganese were several fold greater in the conceptus than in other reproductive tissues, indicating that the conceptus preferentially accumulates these minerals, an action that may be important for conceptus development, growth and survival. Moreover, some recent results indicate that increasing the biological availability of zinc, copper and manganese, by attachment to short peptide chains (i.e., proteinated trace minerals) can enhance reproductive performance of swine. Mineral concentrations in conceptuses from female pigs consuming proteinated trace minerals were greater than those from females that consumed only inorganic mineral salts. Elucidating the mechanisms whereby conceptus development and survival are enhanced by essential trace minerals may lead to development of specific feeding programs to increase the number and health of offspring at parturition, thereby allowing for further improvements in production efficiency in animal agriculture.     

Effects of exposure to environmental chemicals during pregnancy on the development of the male and female reproductive axes

There is a large body of literature describing effects of environmental chemicals (ECs), many of them anthropogenic with endocrine-disrupting properties, on development in rodent laboratory species, some of which lead to impaired reproduction and adverse health. This literature joins extensive human epidemiological data and opportunistic wildlife findings on health effects of ECs. In contrast, the effect of endocrine disruption on foetal development and reproductive performance in domestic species is less extensively documented. This applies both to domestic farm and to companion species even though the former is critical to food production and the latter share our homes and many aspects of the modern developed human lifestyle. In domestic species, the nature of chemicals exposure in utero and their consequences for animal health and production are poorly understood. A complication in our understanding is that the pace of development, ontogeny and efficiency of foetal and maternal hepatic and placental activity differs between domestic species. In many ways, this reflects the difficulties in understanding human exposure and consequences of that exposure for the foetus and subsequent adult from epidemiological and largely rodent-based data. It is important that domestic species are included in research into endocrine disruption because of their (i) wide variety of exposure to such chemicals, (ii) greater similarity of many developmental processes to the human, (iii) economic importance and (iv) close similarities to developed world human lifestyle in companion species.     

Impact of endocrine disrupting chemicals on reproduction in Japanese quail

Many environmental contaminants can interact with the endocrine system, thereby potentially disrupting the reproductive fitness of individuals. In avian species, the egg-yolk is a major route for excretion of lipophilic compounds by the adult female bird and embryos are exposed to contaminants that have been deposited in the eggs. The reproductive and neuroendocrine system of Japanese quail undergoes sexual differentiation during embryo development. The phenotypic sex, including sex-specific adult behavior, is hormonally imprinted already before hatching. The sexual differentiation of the brain in quail is sensitive to estrogens and the presence of estrogen results in a female phenotype. The relatively low concentration of estrogens in male embryos, on the other hand, results in a male behavioral phenotype. The behavior of male quail can be demasculinized by estrogen exposure during the period of sexual differentiation, and estrogen-exposed males are not able to display a male-typical behavior as adults. Also, differentiation of the reproductive organs is sensitive to hormones during embryogenesis, and an excess of estrogens can for instance induce persistent morphological changes in the reproductive organs of females. Our research has focused on effects in adult birds after embryonic estrogen exposure. We have studied sexual behavior and other reproductive variables in adult quail after in ovo injection of known and suspected estrogenic compounds. Synthetic estrogens and insecticides, such as o,p'-DDT altered the development of the neural system and resulted in demasculinization of male quail. In females, o,p'-DDT caused morphological changes of the oviduct and egg laying was reduced. Our studies suggest that the neural system and the female reproductive system of avian embryos are very sensitive to the effects of chemicals with estrogenic activity.     

Endocrine disrupting compounds and farm animals: their properties,actions and routes of exposure

Endocrine disrupting compounds (EDC) comprise a diverse group of compounds of anthropogenic origin, including organochlorine pesticides, alkyl phenols, phthalates, polychlorinated biphenyls (PCB), dioxins and polybrominated diphenyl ethers. EDC are generally present in the environment at low concentrations but they are ubiquitous and persistent and, although environmental concentrations are low, they appear to exert a range of adverse effects on animals of many species, including humans. Their effects include disruption of reproductive function and of the immune system and they can be carcinogenic. Animals may be exposed to relatively high concentrations of EDC because they persist in the environment and when ingested, they may be concentrated in fat tissue and released when the fat is mobilised during pregnancy or lactation, thus exposing, to relatively high concentrations, embryos and neonates. These stages of development are particularly susceptible to EDC effects. Very little is known of EDC body burdens in domestic animal species and particularly in those exposed to unpolluted environments. EDC concentrations in soils and plant material and their rates of ingestion and metabolism have been little studied but it is concluded that there is a potential risk of significant bioaccumulation and of associated effects on the health and reproductive capacity of domestic animals and of humans consuming animal products.     

Effects of artificial supplemental light on the reproductive season of geese kept in open houses

1. New lighting programmes were designed to change the pattern of goose reproduction, based on the response of predictable avian photoperiodic stimulation. The objective of this study was to evaluate the efficiency of a long photoperiod of 20L on shifting goose reproduction to the non-breeding season in an open housing system. 2. Eighty mature White Roman geese were randomly allocated into 4 groups (male:female = 1:4). The supplemental lighting programmes with a daily photoperiod of 20 h were initiated on 22 November and withdrawn when 90% of geese were moulting in the treatment groups. Artificial light intensities of 220, 120 and 20 lux were provided to experimental groups A, B and C, respectively. In contrast, the geese in control group D were kept under natural lighting conditions throughout this study. 3. The annual reproductive curves of all the experimental groups consisted of two separate laying periods. The first period was induced by the supplemental lighting programme while the second was induced by the naturally increasing photoperiod in this subtropical region. The first laying period of the experimental groups occurred in the breeding season, and the second was relocated to the non-breeding season. 4. The supplemental lighting could shift the laying periods of geese to the non-breeding season and had no significant effect on annual reproductive performance. The supplemental light programmes described here were able to manipulate the reproductive season of geese reared in open houses, which would be of practical value.     

The effect of a parenteral ivermectin/closantel injection on the growth and reproductive development of early immature Fasciola hepatica in cattle

Sixteen calves approximately 6 months old were each infected with 500 metacercariae of Fasciola hepatica. Thirty-two days later they were weighed and divided into two groups, and on day 35 all calves in one of the groups were injected subcutaneously with an ivermectin/closantel combination. Both groups were sacrificed between days 70 and 72 to enable counting and examination of the flukes recovered from the bile ducts. Eggs released by the flukes were collected for incubation, hatching and estimation of egg viability. Flukes were counted, flat-fixed in 70% ethanol, stained with catechol and carmine and measured. The reproductive organs, namely testis, vitelline glands, ovary and uterus, were examined and scored on a 0-3 scale according to their state of development. This was visually assessed on the basis of size, distribution and staining density of their constituent tissues and the abundance of eggs in the uterus. A representative sample of flukes from each animal was fixed in formalin for histological sectioning to enable more detailed examination of the reproductive structures. Treatment of the immature flukes reduced the population in cattle by 42.6% as compared with the controls and as a result of the stunting effect due to the presence of closantel during early development the size of treated flukes was reduced by 43.9%. A bimodal pattern of size and reproductive score was also observed in flukes from treated cattle, suggesting that the stunting effect on individual flukes differed depending on whether or not they had gained access to the bile ducts or were still migrating in the hepatic parenchymal tissue at the time of drug exposure with the effect being greater once the fluke had gained access to the bile ducts. The mean reproductive score for untreated flukes was 8.76 and for treated flukes 5.64, a 35.6% reduction. This difference was highly significant (p<0.001). Egg shedding from treated flukes was significantly less than that from controls (p<0.05), but there were no differences in hatchability, suggesting that whilst drug treatment reduced the energy supply available for gametogenesis/oogenesis, it did not induce functional defects in the gonads or accessory reproductive organs. Histological examination confirmed that there was a reduction in development of testes, ovaries and vitellaria in treated flukes, with a consequent reduction in egg production. In the treated flukes, early spermatogonia and oogonia were the predominant cell types in the testes and ovary, whilst undifferentiated stem cells were abundant in the vitelline follicles. In untreated flukes, cells representing more advanced stages in gametogenesis and vitellogenesis predominated in the respective organs. It is likely that this inhibition of gametogenesis and vitellogenesis was caused by the effects of closantel treatment on intermediary metabolism in the flukes. Clearly these effects were evident even at a relatively early stage of fluke growth, and because of the impact on egg output may have epidemiological importance in addition to the reduction in fluke numbers.     

鸡生殖道相关淋巴组织研究进展

It is of great importance to learn about the changes of reproductive tract mucosal immune status by studying the normal development of hens, especially during the immediate post-hatch and laying period, because the chicken reproductive tract associated lymphoid tissue （RTALT） is the first immune barrier of the genitourinary tract against the invasion of external pathogenic microorganisms. This study can serve as a theoretical basis of the reproductive tract disease prevention (especially salmonellosis) for laying hens, and ultimately achieve the goal of providing pollution-free eggs for people to consume. Therefore, this article on chicken reproductive tract associated lymphoid tissue structural basis for development as well as their immune function were reviewed.     

Effects of seasonal and physiological variations on the serum chemistry, vitamins and thyroid hormone concentrations in sheep

The aim of this study was to investigate the possible effects of the reproductive status and seasonal variations on the serum chemistry and vitamin status and their relationships with the thyroid hormones in Sakiz-Awassi crossbreed sheep. The sheep (n = 34) were divided into two groups. The first group (n = 22) was mated; the second group (n = 12) was not mated. Their serum samples were collected four times a year at the each season and under reproductive status. The periods are 1, early pregnancy (October); 2, late pregnancy (January); 3, lactation (April); and 4, dry season (July). The results of this study indicated that (1) total protein (TP), globulin, cholesterol, creatinine, uric acid and T4/T3 vary with reproductive status but not seasonal variations; (2) alanine aminotransferase, T4, fT4 concentrations in serum vary only with reproductive status; (3) the urea, creatine kinase, lactate dehydrogenase, alkaline phosphatase, aspartate aminotransferase, amylase, albumin, triglyceride, VLDL, Vit A-E, T3 and fT3 concentration could vary with both reproductive status and seasonal variations; (4) the glucose, gamma-glutamyl transpeptidase, folate concentrations were altered neither season of the year nor the reproductive status; (5) a single reference interval for folate, gamma-glutamyl transpeptidase (GGT), glucose, TP, globulin, cholesterol, creatinine, uric acid and T4/T3 can be used for both mated and non-mated sheep because of no differences were found due to the reproductive status. Taking the results together suggests that reproductive status and seasonal variations have to be taken into consideration for a correct interpretation of the serum chemistry values of sheep. Nutritional supplements are required for sheep during certain periods to avoid a decline of their performance, which would then represent consequent economic, loses.     

The use of microbiological end-points in the safety evaluation and elaboration of maximum residue limits for veterinary drugs intended for use in food producing animals

The safety evaluation of veterinary drugs intended for use in food producing animals relies heavily on the results of toxicity studies in laboratory animals, supported where possible by any data resulting from human exposure. The general approach involves the calculation of an acceptable daily intake which in turn can be used to elaborate maximum residue limits. It is an approach used in the European Union, in other countries and at the international level. In recent years, concern has been expressed over the presence of microbiologically active residues of veterinary drugs in food and their possible effects on the human gastrointestinal microflora. Methodologies for conducting microbiological safety studies have been investigated and approaches to microbiological safety assessments have been debated. The whole approach has proved to be controversial, partly because there are considerable doubts over the ability of low concentrations of antibiotic substances to produce adverse effects on the human gut flora and partly because there are no validated methods for testing for these attributes. This paper reviews the problems in some detail and discusses the regulatory consequences.