Reproduction In Ruminants Research Articles

Polyunsaturated Fatty Acids in Male Ruminant Reproduction - A Review.

Fatty acids such as n-3 and n-6 polyunsaturated fatty acids (PUFA) are critical nutrients, used to improve male reproductive performance through modification of fatty acid profile and maintenance of sperm membrane integrity, especially under cold shock or cryopreservation condition. Also, PUFA provide the precursors for prostaglandin synthesis and can modulate the expression patterns of many key enzymes involved in both prostaglandin and steroid metabolism. Many studies carried out on diets supplemented with PUFA have demonstrated their capability to sustain sperm motility, viability and fertility during chilling and freezing as well as improving testis development and spermatogenesis in a variety of livestock species. In addition to the type and quantity of dietary fatty acids, ways of addition of PUFA to diet or semen extender is very crucial as it has different effects on semen quality in male ruminants. Limitation of PUFA added to ruminant ration is due to biohydrogenation by rumen microorganisms, which causes conversion of unsaturated fatty acids to saturated fatty acids, leading to loss of PUFA quantity. Thus, many strategies for protecting PUFA from biohydrogenation in rumen have been developed over the years. This paper reviews four aspects of PUFA in light of previous research including rumen metabolism, biological roles, influence on reproduction, and strategies to use in male ruminants.

In vitro effects of deoxynivalenol and zearalenone major metabolites alone and combined, on cell proliferation, steroid production and gene expression in bovine small-follicle granulosa cells

The effects of deoxynivalenol (DON) and zearalenone (ZEA) on reproduction in ruminants are unclear. This study was performed to evaluate the impact of DON and ZEA hydroxylated metabolites, α-zearalenol (α-Zol) and β-zearalenone (β-Zol), on cell proliferation, steroidogenesis and gene expression using bovine granulosa cells (GC). Cell proliferation was negatively affected after exposure to β-Zol at 31 μM and after exposure to α-Zol (3.1 μM) alone and combined with DON (3.3 μM). DON and α-Zol decreased steroidogenesis, while β-Zol at high concentration had stimulatory effects. DON and β-Zol increased CYP19A1 mRNA abundance. CYP11A1 mRNA abundance was stimulated by DON, alone and combined with α-Zol and β-Zol, whereas was inhibited by β-Zol alone. Generally mycotoxins effects on cell proliferation, steroidogenesis and gene expression were influenced by the presence or absence of IGF1. In conclusion DON and ZEA metabolites may impair in vitro cell proliferation, steroid production and gene expression in cattle.

Impactos do uso da somatotropina bovina recombinante (rbST) sobre a reprodução de ruminantes*

Recombinant Bovine Somatotropin (rbST) has been identified as a substance that can positively impact the reproduction of ruminants, there are, however, few studies published of its use in this area, perhaps because rbST has been banned in many countries. Also known as growth hormone, somatotropin causes favorable reactions related to improving reproductive characteristic such as conception rate, in vitro maturation of oocytes, in vitro embryo culture among others. More studies are needed in order to better understand the effects of rbST and its possible use as a tool to improve the reproduction of ruminants. This article is a review of the literature on the possible effects of rbST in the reproduction of ruminants.

Identification of novel and differentially expressed microRNAs in ovine ovary and testis tissues using Solexa sequencing and bioinformatics

MicroRNAs (miRNAs) are small, single stranded, non-coding RNA molecules, about 19–25 nucleotides in length, which regulate the development and functions of reproductive system of mammal. To discover novel miRNAs and identify the differential expression of them in ovine ovary and testis tissues, the study constructed two libraries by using next-generation sequencing technologies (Solexa high-throughput sequencing technique). As a result, 9 321 775 and 9 511 538 clean reads were obtained from the ovary and testis separately, which included 130 562 (90 genes of ovary) and 56 272 (85 genes of testis) of known miRNAs and 486 potential novel miRNAs reads. In this study, a total of 65 conserved miRNAs were significantly differentially expressed (P<0.01) between the two samples. Among them, 28 miRNAs were up-regulated and 3 miRNAs were down-regulated on ovary compared with testis. In addition, the known miRNAs with the highest expression level (5 miRNAs) and 30 novel miRNAs with the functions related to reproduction were validated using the real-time quantitative RT-PCR. Moreover, the gene ontology (GO) annotation and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis showed that differentially expressed miRNAs were involved in ovary and testis physiology, including signal transduction, gonad development, sex differentiation, gematogenesis, fertilization and embryo development. The results will be helpful to facilitate studies on the regulation of miRNAs during ruminant reproduction.

Organic Zinc as Feed Additive for Ruminants

Zinc is an essential micro mineral required by ruminants and is a component of over 300 enzymes which play important role in the metabolisms of carbohydrates, proteins and fats. Recently, the chemical and biotechnology processes have been developed for synthesizing organic Zn. Organic Zn is the product of a chelating process of dissolved Zn anorganic salts with amino acids or hydrolyzed protein. The utilization of organic Zn as feed additive in ruminants diets tends to increase, due to the absorption of Zn in the organic form is more effective than the inorganic form. This paper reviewes the research from comparative studies of inorganic and organic Zn on the growth, production and reproduction in ruminants. The studies found that the supplementation of organic Zn improved nutrient digestibility, growth, feed efficiency, milk production, Zn retention and absorption, production and reproductive performances of ruminants. However, a little variation response was found due to different degrees of chelating on Zn incorporation of amino acids or hydrolyzed protein. K e y words: Organic Zn, characteristic, supplementation, performance, ruminants

Lysophosphatidic acid (LPA) signaling in human and ruminant reproductive tract.

Lysophosphatidic acid (LPA) through activating its G protein-coupled receptors (LPAR 1–6) exerts diverse cellular effects that in turn influence several physiological processes including reproductive function of the female. Studies in various species of animals and also in humans have identified important roles for the receptor-mediated LPA signaling in multiple aspects of human and animal reproductive tract function. These aspects range from ovarian and uterine function, estrous cycle regulation, early embryo development, embryo implantation, decidualization to pregnancy maintenance and parturition. LPA signaling can also have pathological consequences, influencing aspects of endometriosis and reproductive tissue associated tumors. The review describes recent progress in LPA signaling research relevant to human and ruminant reproduction, pointing at the cow as a relevant model to study LPA influence on the human reproductive performance.

Reproductive seasonality in captive wild ruminants: implications for biogeographical adaptation, photoperiodic control, and life history

Many ruminant species show seasonal patterns of reproduction. Causes for this are widely debated, and include adaptations to seasonal availability of resources (with cues either from body condition in more tropical, or from photoperiodism in higher latitude habitats) and/or defence strategies against predators. Conclusions so far are limited to datasets with less than 30 species. Here, we use a dataset on 110 wild ruminant species kept in captivity in temperate-zone zoos to describe their reproductive patterns quantitatively [determining the birth peak breadth (BPB) as the number of days in which 80% of all births occur]; then we link this pattern to various biological characteristics [latitude of origin, mother-young-relationship (hider/follower), proportion of grass in the natural diet (grazer/browser), sexual size dimorphism/mating system], and compare it with reports for free-ranging animals. When comparing taxonomic subgroups, variance in BPB is highly correlated to the minimum, but not the maximum BPB, suggesting that a high BPB (i.e. an aseasonal reproductive pattern) is the plesiomorphic character in ruminants. Globally, latitude of natural origin is highly correlated to the BPB observed in captivity, supporting an overruling impact of photoperiodism on ruminant reproduction. Feeding type has no additional influence; the hider/follower dichotomy, associated with the anti-predator strategy of 'swamping', has additional influence in the subset of African species only. Sexual size dimorphism and mating system are marginally associated with the BPB, potentially indicating a facilitation of polygamy under seasonal conditions. The difference in the calculated Julian date of conception between captive populations and that reported for free-ranging ones corresponds to the one expected if absolute day length was the main trigger in highly seasonal species: calculated day length at the time of conception between free-ranging and captive populations followed a y = x relationship. Only 11 species (all originating from lower latitudes) were considered to change their reproductive pattern distinctively between the wild and captivity, with 10 becoming less seasonal (but not aseasonal) in human care, indicating that seasonality observed in the wild was partly resource-associated. Only one species (Antidorcas marsupialis) became more seasonal in captivity, presumably because resource availability in the wild overrules the innate photoperiodic response. Reproductive seasonality explains additional variance in the body mass-gestation period relationship, with more seasonal species having shorter gestation periods for their body size. We conclude that photoperiodism, and in particular absolute day length, are genetically fixed triggers for reproduction that may be malleable to some extent by body condition, and that plasticity in gestation length is an important facilitator that may partly explain the success of ruminant radiation to high latitudes. Evidence for an anti-predator strategy involving seasonal reproduction is limited to African species. Reproductive seasonality following rainfall patterns may not be an adaptation to give birth in periods of high resource availability but an adaptation to allow conception only at times of good body condition.

Creating new knowledge for ruminant reproduction from rapidly expanding and evolving scientific databases

Declining fertility is a major problem for the dairy industry. Recent developments of Omics-technologies facilitate a comprehensive analysis of molecular patters in gametes, embryos and tissues of the reproductive tract which may help to identify the reasons for impaired fertility. Large Omics-datasets require appropriate bioinformatics analysis in the context of rapidly expanding and evolving scientific databases. This overview summarizes the current status of ruminant genome projects, describes currently existing resources for ruminant genomics, transcriptomics and proteomics as well as databases and tools for the interpretation and exploitation of transcriptomics and proteomics datasets. Gene set enrichment analysis (GSEA) and transcription factor binding site (TFBS) analyses are strategies for the identification of regulatory genes. In general, the comprehensive analysis of molecular traits by Omics-technologies can enhance the interpretation of genome-wide association studies, providing insights into the biological pathways linking genotype and phenotype, and their modulation by endogenous and environmental factors.

Fatores nutricionais associados à reprodução da fêmea bovina

O conhecimento da importância da nutrição sobre a reprodução dos animais, por produtores e pesquisadores, vem de longa data. Entretanto, estudos contemporâneos têm trazido novas perspectivas e informações mais detalhadas desta relação, permitindo um ajuste fino nas manipulações de dietas com o propósito de aumentar a produção e a reprodução em ruminantes. Apesar disso, especialmente em vacas de elevada produção leiteira, ainda há sérios problemas de fertilidade de ordem multifatorial, mas com grande envolvimento nutricional. Por outro lado, adição de certos ingredientes à dieta, como gordura rica em ácidos graxos polinsaturados, e redução do fornecimento de proteína degradável no rúmen têm, em diversas ocasiões, resultado em incremento nos índices reprodutivos em bovinos leiteiros e de corte. Nesse sentido, este artigo tem a proposta de apresentar e discutir resultados de alguns trabalhos relevantes sobre o tema, principalmente aqueles relacionados à influência da energia ou proteína sobre a reprodução.

93 POSTCRYOPRESERVATION VIABILITY OF EMBRYOS FROM NELLORE HEIFERS SUPPLEMENTED WITH RUMEN-PROTECTED FAT

Polyunsaturated fatty acids seem to exert an extra-caloric positive effect on ruminant reproduction, although the reasons for that are still unclear. Although some studies have detected a positive effect of feeding unsaturated fatty acids on embryo development of superovulated Bos taurus cattle (Thangavelu et al. 2007 Theriogenology 68, 949-957), others have not (Petit et al. 2008 J. Dairy Sci. 91, 1786-1790). Our hypothesis was that, although number and quality of embryos from superovulated heifers would not be affected by diet, supplemental fat would improve embryo cryotolerance. Therefore, this study evaluated superovulatory response and embryo production, as well as cryotolerance of embryos cryopreserved through freezing or vitrification in Nellore heifers supplemented with rumen-protected fat. Forty heifers (24 to 36 mo old) were kept in pasture and randomly divided into 2 experimental groups according to supplemental source [F = concentrate with rumen-protected fat (100 g/d of Megalac-E®) and C = control, without fat supplementation]. Supplements were formulated to be isocaloric and isoproteic. Each female underwent both treatments in a cross-over design with approximately 68 d between replicates. After 50 d of feeding, emergence of the wave was synchronized with the aid of hormones to initiate the superovulation protocol. Recovered embryos were frozen or vitrified, and subsequently in vitro embryo development evaluation was accomplished. Data were analyzed using generalized linear models. There was no difference between F and C groups (P &gt; 0.10) regarding superstimulatory response, number of total embryos/ova, viable embryos, degenerate embryos, or unfertilized oocytes recovered. However, group C had a greater superovulatory response than F (18.0 ± 1.3 v. 15.7 ± 1.2 CL; P = 0.06). Group C embryos presented greater hatching rate, independently of the cryopreservation method, at 48 h (33.1 ± 4.0%; n = 148 v. 17.3 ± 3.3%; n = 137; P = 0.009) and at 72 h (44.3 ± 4.2%; n = 148 v. 30.9 ± 4.0%; n = 137; P = 0.04) of in vitro culture. Under the conditions of the present study, supplementation with protected fat did not affect superstimulatory response and quantity or quality of embryos. However embryos from the F group were less tolerant to cryopreservation. Financial support from FAPESP, EMBRAPA, Arm &amp; Hammer, Integral Produbon, and Pfizer of Brazil.

Plasma retinol concentration in grazing heifers: First data obtained from a dairy herd in the south of Chile

Vitamins are organic molecules with a complex structure, which are essential in very small quantities for the health, growth and reproduction of ruminants. The generic term vitamin A is used when referring to retinoids that exhibit the biological activity of retinol (IUNS 1990)and includes both natural forms and synthetic analogues. Vitarnin A is physically a pale yellow crystalline solid substance, which is water insoluble. Chemically, it is a hydrophobic â-ionone ring with a conjugated isoprenoid lateral chain containing a polar group at its end (Debier and Larondelle 2005). The ability to synthesizecompoundswith vitamin A activity is limited to microorganisms and plants (Harrison 2005). Thus, animals must obtain vitamin A from the diet, where it can be found as a preformed vitamin in animal foods or as a provitarnin in plant foods. Provitamins are members of the carotenoid family, and the term is used as a generic description of all the compounds that exhibit qualitatively the biological activity of â-carotene (IUNS 1990). Â-carotene is one of the most widely available carotenoids and the main precursor of vitamin A (During and Harrison 2004). It is known that in animals, vitamin A intervenes in a variety of biological mechanisms associated to the maintenance of epithelial cells, gene regulation, immune cell function, reproduction and vision (Chew 1987, Debier and Larondelle 2005). Due to the above mentioned, the most frequent signs of deficiency are: impaired dark adaptation, xerophthalmia with the cornea becoming thick and hazy, decreased cellular and humoral immunity. In male animals it can cause degenerative damage of epithelial cells in seminiferous tubules while in the female it leads to abortion, delivering stillborn or weak foetuses and placental retention (Radostits et al 2002). According to Herdt and Stowe (1991) the evaluation of vitamin A metabolic balance is not a routine practice in animals but it should be considered as part of the general health diagnosis of the herd, especially if there is evidence of a decrease in reproductive efficiency and immunosuppression of unknown origino Hammell et al (2000) have mentioned that the hepatic concentration of vitamin A is the most reliable indicator used to evaluate the metabolic balance of vitamin A in animals. However, even though the determination of plasma concentration of retinol is a less sensitive indicator, it is the most practical and useful method to evaluate the status of vitamin A in the herd (Herdt and Stowe 1991), with plasma concentrations between 25 and 60 µg/dL indicating an acceptable level ofthe vitamin adult cattle (Frye et al 1991). Plasma concentration of vitamin A is usually expressed as the addition of retinol and retinyl palmitate concentrations; however, retinol gives more clinical information and can be measured through chromatographic techniques (Herdt and Stowe 1991). High Performance Liquid Chromatography (HPLC) is used to separate molecules with a high analytical sensitivity (Paulo et al 1999), making it a useful tool to determine vitamin concentration in bovines. Retinol requirements have been the subject of many studies. According to ARC (1980) the daily requirements of retinol are 20 µg/kg of body weight for maintenance and growth, 30 µg/kg of body weight during breeding and pregnancy and 25 to 65 µg/kg of body weight for lactating cows. NRC (2001) mentions that vitamin A, expressed as retinol equivalents, should be supplemented in amounts of 24 µg/kg of body weight during growth and 33 µg/kg of body weight during lactation, pointing out that these values do not represent the total requirement of the vitamin and consider animals being fed conserved forage. In the south of Chile, the management system for dairy cows is based on grazing pasture and the supplementation with concentrate and conserved forage is used in critical periods (Pulido et al 1999). Considering that green fresh forage is the main source of vitamin A precursors, it is possible to estimate that the contribution should be adequate for grazing cattle; however, the quality and quantity of the forage provided by the pasture changes throughout the year, under which circumstances the nutrient contribution could vary. Furthermore, most grains are void of carotenoids and the stored forages have lower concentrations of them (NRC 2001). In Chile there are no records about vitamin A status in dairy neither beef cattle; it could limit the nutritional management and the efficiency of the herd. The aim of this study was to measure the plasma retinol concentration in grazing heifers using a standardized analytic methodology and to record its variation during winter and spring in a herd in southern Chile.

Meat and Livestock Association Plenary Lecture 2005. Oocyte signalling molecules and their effects on reproduction in ruminants

Sheep (Ovis aries) are a highly diverse species, with more than 900 different breeds that vary significantly in their physiological characteristics, including ovulation rate and fecundity. From examination of inherited patterns of ovulation rate, several breeds have been identified with point mutations in two growth factor genes that are expressed in oocytes. Currently, five different point mutations have been identified in the BMP15 (GDF9b) gene and one in GDF9. Animals heterozygous for the GDF9 and/or the BMP15 mutations have higher ovulation rates than their wild-type counterparts. In contrast, those homozygous for any of the aforementioned BMP15 or GDF9 mutations are sterile owing to arrested follicular development. In bovine and ovine ovaries, GDF9 was expressed exclusively in oocytes throughout follicular growth from the primordial stage of development, whereas in sheep BMP15 was expressed exclusively in oocytes from the primary stage: no data for the ontogeny of BMP15 expression are currently available for cattle. In vitro, ovine growth differentiation factor 9 (oGDF9) has no effect on (3)H-thymidine incorporation by either bovine or ovine granulosa cells, whereas ovine bone morphogenetic protein 15 (oBMP15) has modest (1.2- to 1.6-fold; P < 0.05) stimulatory effects. Ovine GDF9 or oBMP15 alone inhibited progesterone production by bovine granulosa cells, whereas in ovine cells only oGDF9 was inhibitory. The effects of oGDF9 and oBMP15 together were often cooperative and not always the same as those observed for each factor alone. Active immunisation of ewes with BMP15 and/or GDF9 peptides affected ovarian follicular development and ovulation rate. Depending on the GDF9 and/or BMP15 vaccine formulation, ovulation rate was either increased or suppressed. A primary and single booster immunisation of ewes with a BMP15 peptide in a water-based adjuvant has led to 19-40% increases in lambs born per ewe lambing. Collectively, the evidence suggests that oocyte signalling molecules have profound effects on reproduction in mammals, including rodents, humans and ruminants. Moreover, in vivo manipulation of these oocyte signalling molecules provides new opportunities for the management of the fertility of ruminants.

The Impact of Saponins or Saponin-Containing Plant Materials on Ruminant ProductionA Review

Saponins are steroid or triterpene glycoside compounds found in a variety of plants. Some saponin-containing plants, mainly legumes, have been used as animal feed, but others are toxic. Several studies on the effect of saponins on ruminant production have also been reported. Some in vitro and in vivo experiments that demonstrate the beneficial effects of saponin such as defaunation of the rumen and manipulation of the end products of fermentation are described. Defaunation is the selective removal of protozoa from the rumen microbial ecosystem by a cell membrane cholesterol-saponin interaction, which causes cell rupture. Because protozoa in the rumen cause protein turnover by predating on bacteria, defaunation increases the nitrogen utilization of the ruminant and may lead to an increase in growth, milk, or wool production. The growth-promoting effect was evident in the high roughage diet suggesting that the application of saponins or saponin-containing plant materials may be beneficial for the subsistence farmers in developing countries. Saponins are deglycosylated by rumen microbes. Some sapogenins have been detected in the digestive tract of ruminants; however, the direct action of these compounds on the host animal is still unclear. No information on the effects of saponin on ruminant reproduction is available. There is an urgent need for a systematic evaluation of the most active structural components of the saponins, and their interaction with the microbial community, the host animal, and the diet. Along with these studies, the direct effects of saponins or their microbial degradation products on the host must be examined in order to get the full understanding of the metabolism and beneficial effects of saponins on animals.

020. Oocyte signalling molecules and their effects on reproduction in ruminants

Sheep (Ovis aries) are a highly diverse species with more than 900 different breeds that vary significantly in their physiological characteristics including ovulation rate and fecundity. From examination of inherited patterns of ovulation rate in sheep, several breeds have been identified with point mutations in two growth factor genes that are expressed in oocytes. Currently, five different point mutations have been identified in the BMP15 (GDF9b) gene and one in GDF9. Animals heterozygous for the GDF9 and/or the BMP15 mutations have higher ovulation rates (i.e. +0.6 to +5.0) than their wild-type contemporaries. In contrast, those homozygous for any of the aforementioned BMP15 or GDF9 mutations are sterile due to abnormal follicular development from the primary stage of growth. In bovine and ovine ovaries, GDF9 is expressed exclusively in oocytes throughout follicular growth from the primordial stage of development, whereas in sheep BMP15 is expressed exclusively in oocytes from the primary stage: no data for BMP15 are available for the cow. In vitro, ovine GDF9 (oGDF9) has no effect on 3H-thymidine incorporation by either bovine or ovine granulosa cells, whereas oBMP15 has modest (1.2 to 1.6-fold; P &lt; 0.05) stimulatory effects. GDF9 or BMP15 alone inhibited progesterone production by bovine granulosa cells, whereas with ovine cells only GDF9 was inhibitory. The effects of GDF9 and BMP15 together were often cooperative and not always the same as those observed for each factor alone. Active immunisation of ewes with BMP15 and/or GDF9 peptides affected ovarian follicular development and ovulation rate. Depending on the GDF9 and/or BMP15 vaccine formulation, ovulation rate was either increased or suppressed. For example, immunisation of ewes with a BMP15 peptide in a water based adjuvant has led to a 25% increase in lambs born per ewe lambing. Collectively the evidence suggests that oocyte signalling molecules have profound effects on reproduction in mammals including rodents, humans and ruminants. Moreover, that in vivo manipulation of these oocyte signalling molecules provides a new approach to managing the fertility of ruminants.

Epidemiological evidence of effects of EDC on ruminant reproduction

Fifty percent of Dutch dairy farmers use surface water as the main source of drinking water for their cows during the grazing season. In many locations this surface water is in direct contact with a sewerage overflow. Belfroid and coworkers (1999) have demonstrated that this sewerage overflow surface water contains EDC, in particular xeno-oestrogens. The concentration of conjugated ethinyl-oestradiol, for example, in sewerage water was 0.02 mg/l. During the last decade the fertility of dairy cows has decreased dramatically. There is an increased incidence of cystic ovaries, an increase in the interval from calving to first insemination, an increase in the number of inseminations per pregnancy and more abortions have been recorded. These observations raise the possibility that EDC’s adversely affect reproduction in dairy cows. Meijer et al. (1999) compared the production and fertility of cows on 397 farms that used normal surface water with the production and fertility of cows on 60 farms that used water in direct contact with sewerage overflow. The results showed clearly that cows drinking water that was in direct contact with sewerage overflow produced less milk and had a greater age at first calving. Moreover they exhibited a tendency towards a longer interval between calving and first succesful insemination and tended to have a higher rate of abortions. Boerjan et al. (2001) have recently addressed the issues of concentrations of xeno-estrogens present in soil, in plants, in water and in cow tissues, milk and blood, in order to assess the potential risk to ruminants of xeno-estrogen exposure through soil and water ingestion. Although data are sparse and concentrations of EDC in feed and water of ruminant animals are low, under certain circumstances such as sewerage overflow and sludge-fertilized pasture, they concluded that rates of ingestion of certain xeno-oestrogens may exceed levels at which there is no effect. Since most EDC’s are lipophilic and become concentrated in adipose tissue, the mobilisation of fat during onset of lactation and pregnancy can expose animals to much higher concentrations of xeno-estrogens than are present normally in the environment. Important questions are: 1)how much of the EDC’s stored in fat cells will enter the blood under certain circumstances2)how much of the EDC’s in soil, water and plants will pass the rumen and enter also the blood and3)how potent are the different EDC’s i.e. what is the dose response relationship? In order to answer the last question an in vivo animal-model is urgently needed.We have developed an animal-model, based on the genital tract of an ovariectomized cow; the height and organisation of the endometrial lumen-epithelium, the rate of oedema in the stratum compactum and the electrical resistance of the cervical mucus are sensitive measures of oestrogenic activity.

Effects of dietary fatty acids on reproduction in ruminants

Fats in the diet can influence reproduction positively by altering both ovarian follicle and corpus luteum function via improved energy status and by increasing precursors for the synthesis of reproductive hormones such as steroids and prostaglandins. Dietary fatty acids of the n-3 family reduce ovarian and endometrial synthesis of prostaglandin F2alpha, decrease ovulation rate in rats and delay parturition in sheep and humans. Polyunsaturated fatty acids such as linoleic, linolenic, eicosapentaenoic and docosahexaenoic acids may inhibit prostaglandin F2alpha synthesis through mechanisms such as decreased availability of its precursor arachidonic acid, an increased competition by these fatty acids with arachidonic acid for binding to prostaglandin H synthase, and inhibition of prostaglandin H synthase synthesis and activity. It is not known whether polyunsaturated fatty acids regulate expression of candidate genes such as phospholipase A2 and prostaglandin H synthase via activation of nuclear transcription factors such as peroxisome proliferator-activated receptors. Manipulation of the fatty acid profile of the diet can be used potentially to amplify suppression of uterine synthesis of prostaglandin F2alpha during early pregnancy in cattle, which may contribute to a reduction in embryonic mortality. Feeding fats and targeting of fatty acids to reproductive tissues may be a potential strategy to integrate nutrition and reproductive management to improve animal productivity.

Effects of dietary fatty acids on reproduction in ruminants

Effects of dietary fatty acids on reproduction in ruminants

Reproductive effects of fenoxycarb on sheep.

Fenoxycarb (ethyl [2-(4-phenoxyphenoxy)-ethyl] carbamate) is an insect growth regulator used for long-term fire ant control. Because of its effects on insect reproduction and its potential use on pasturage consumed by food animals, a reproductive study was conducted using Rambouillet sheep. The sheep were dosed daily with a placebo or with fenoxycarb at 0.69 or 1.38 mg/kg/day, representing ten (10x) and 20 times (20x) the maximum amounts of fenoxycarb in forage or hay treated at recommended levels for fire ant control. Parameters that were measured included rates of weight gain of adults, serum clinical chemistry profiles of adults, spermatozoal morphology and motility, estrus cycling, pregnancy rates, maintenance of pregnancies to term, numbers of live births, and rates of weight gain of lambs to 28 days. There were no statistically significant (P < or = 0.05) differences between the exposed and control groups of sheep in any of these facets of the study. No clinical signs associated with exposure to fenoxycarb were observed in any animal at any time, and no exposure-related pattern of pathologic lesions or reproductive organ histology was observed. Means of hepatic fenoxycarb residues in the rams followed a statistically significant (P < or = 0.05) dose-related pattern. No fenoxycarb was detected (detection limit of 5 ppb) in any neonatal liver, despite the presence of hepatic fenoxycarb residues in the treated ewes, indicating that transplacental transport of fenoxycarb was minimal. No fenoxycarb was detected in any lamb liver at 28 days, although both the colostrum and the milk of exposed ewes were found to contain fenoxycarb at levels proportional to the treatments. Based on the lack of significant findings in this study, it is unlikely that use of fenoxycarb, according to label instructions (currently applicable to homeowner and registered agricultural usage) for fire ant control in pasturage or hay fields, will affect ruminant reproduction.

Effects of dietary urea on reproduction in ruminants.

Effects of dietary urea on reproduction in ruminants.

Effects of parabiosis of normal with genetically diabetic mice.

Effects of parabiosis of normal with genetically diabetic mice.