Estrous behavior in dairy cows: identification of underlying mechanisms and gene functions

Selection in dairy cattle for a higher milk yield has coincided with declined fertility. One of the factors is reduced expression of estrous behavior. Changes in systems that regulate the estrous behavior could be manifested by altered gene expression. This literature review describes the current knowledge on mechanisms and genes involved in the regulation of estrous behavior. The endocrinological regulation of the estrous cycle in dairy cows is well described. Estradiol (E2) is assumed to be the key regulator that synchronizes endocrine and behavioral events. Other pivotal hormones are, for example, progesterone, gonadotropin releasing hormone and insulin-like growth factor-1. Interactions between the latter and E2 may play a role in the unfavorable effects of milk yield-related metabolic stress on fertility in high milk-producing dairy cows. However, a clear understanding of how endocrine mechanisms are tied to estrous behavior in cows is only starting to emerge. Recent studies on gene expression and signaling pathways in rodents and other animals contribute to our understanding of genes and mechanisms involved in estrous behavior. Studies in rodents, for example, show that estrogen-induced gene expression in specific brain areas such as the hypothalamus play an important role. Through these estrogen-induced gene expressions, E2 alters the functioning of neuronal networks that underlie estrous behavior, by affecting dendritic connections between cells, receptor populations and neurotransmitter releases. To improve the understanding of complex biological networks, like estrus regulation, and to deal with the increasing amount of genomic information that becomes available, mathematical models can be helpful. Systems biology combines physiological and genomic data with mathematical modeling. Possible applications of systems biology approaches in the field of female fertility and estrous behavior are discusse

Systems biology in animal sciences

Systems biology is a rapidly expanding field of research and is applied in a number of biological disciplines. In animal sciences, omics approaches are increasingly used, yielding vast amounts of data, but systems biology approaches to extract understanding from these data of biological processes and animal traits are not yet frequently used. This paper aims to explain what systems biology is and which areas of animal sciences could benefit from systems biology approaches. Systems biology aims to understand whole biological systems working as a unit, rather than investigating their individual components. Therefore, systems biology can be considered a holistic approach, as opposed to reductionism. The recently developed ‘omics’ technologies enable biological sciences to characterize the molecular components of life with ever increasing speed, yielding vast amounts of data. However, biological functions do not follow from the simple addition of the properties of system components, but rather arise from the dynamic interactions of these components. Systems biology combines statistics, bioinformatics and mathematical modeling to integrate and analyze large amounts of data in order to extract a better understanding of the biology from these huge data sets and to predict the behavior of biological systems. A ‘system’ approach and mathematical modeling in biological sciences are not new in itself, as they were used in biochemistry, physiology and genetics long before the name systems biology was coined. However, the present combination of mass biological data and of computational and modeling tools is unprecedented and truly represents a major paradigm shift in biology. Significant advances have been made using systems biology approaches, especially in the field of bacterial and eukaryotic cells and in human medicine. Similarly, progress is being made with ‘system approaches’ in animal sciences, providing exciting opportunities to predict and modulate animal traits

Het seksen van sperma - Wel of niet gewenst in de biologische melkveehouderij?

Het seksen van stierensperma beleeft in de melkveehouderij een snelle opkomst. Het is echter de vraag of in de biologische sector deze techniek wel toelaatbaar is. Ten behoeve van het creëren van duidelijkheid omtrent het gebruik van deze techniek wordt in deze notitie eerst de techniek van het seksen van sperma beschreven zoals die nu wordt uitgevoerd. Daarna wordt kort uiteengezet wat de voor- en nadelen van deze techniek kunnen zijn en wat op basis hiervan de voor en tegens van het wel of niet gebruiken van het seksen van sperma in de biologische landbouw zijn

Cryopreservation of equine oocytes: looking into the crystal ball

In vitro embryo production has evolved rapidly in the horse over the past decade, but blastocyst rates from vitrified equine oocytes remain quite poor and further research is needed to warrant application. Oocyte vitrification is affected by several technical and biological factors. In the horse, short exposure of immature oocytes to the combination of permeating and non-permeating cryoprotective agents has been associated with the best results so far. High cooling and warming rates are also crucial and can be obtained by using minimal volumes and open cryodevices. Vitrification of in vivo-matured oocytes has yielded better results, but is less practical. The presence of the corona radiata seems to partially protect those factors that are necessary for the construction of the normal spindle and for chromosome alignment, but multiple layers of cumulus cells may impair permeation of cryoprotective agents. In addition to the spindle, the oolemma and mitochondria are also particularly sensitive to vitrification damage, which should be minimised in future vitrification procedures. This review presents promising protocols and novel strategies in equine oocyte vitrification, with a focus on blastocyst development and foal production as most reliable outcome parameters

Використання математичного сподівання для швидкого центрування наборів зображень

There is proposed RSA algorithm modification on the based of the form of pixel threads. The used picture must be in the one byte pixel format and allows contour separation

Haan- of eikwestie?

Het systematisch en massaal doden van pas uitgekomen mannelijke kuikens, hoe ethisch is dat? En zijn er geen alternatieven? Deze twee vragen staan in deze bijdrage centraal. Op basis van de dierethische waarden ‘intrinsieke waarde van het dier’, dierenwelzijn en vrijheid om natuurlijk gedrag te vertonen, wordt geconcludeerd dat de gangbare praktijk ethisch zeer problematisch is, ook al worden de gedode haantjes in Nederland voor diervoeder gebruikt. Deze praktijk is vergeleken met seksen en selecteren van het 18-dagen oude embryo. Het verschil wordt ethisch niet groot geacht. Deze praktijk is gevolg van een eenzijdig op doelmatigheid gerichte ontwikkeling waarvoor de overheid en de samenleving als geheel medeverantwoordelijkheid voor dragen. Een echte oplossing vereist een systeemomslag of ten minste de ontwikkeling van geheel nieuwe technieken die het massale doden van eendagshaantjes of bebroede eieren vermijde

Gene expression patterns in anterior pituitary associated with quantitative measure of oestrous behaviour in dairy cows

Intensive selection for high milk yield in dairy cows has raised production levels substantially but at the cost of reduced fertility, which manifests in different ways including reduced expression of oestrous behaviour. The genomic regulation of oestrous behaviour in bovines remains largely unknown. Here, we aimed to identify and study those genes that were associated with oestrous behaviour among genes expressed in the bovine anterior pituitary either at the start of oestrous cycle or at the mid-cycle (around day 12 of cycle), or regardless of the phase of cycle. Oestrous behaviour was recorded in each of 28 primiparous cows from 30 days in milk onwards till the day of their sacrifice (between 77 and 139 days in milk) and quantified as heat scores. An average heat score value was calculated for each cow from heat scores observed during consecutive oestrous cycles excluding the cycle on the day of sacrifice. A microarray experiment was designed to measure gene expression in the anterior pituitary of these cows, 14 of which were sacrificed at the start of oestrous cycle (day 0) and 14 around day 12 of cycle (day 12). Gene expression was modelled as a function of the orthogonally transformed average heat score values using a Bayesian hierarchical mixed model on data from day 0 cows alone (analysis 1), day 12 cows alone (analysis 2) and the combined data from day 0 and day 12 cows (analysis 3). Genes whose expression patterns showed significant linear or non-linear relationships with average heat scores were identified in all three analyses (177, 142 and 118 genes, respectively). Gene ontology terms enriched among genes identified in analysis 1 revealed processes associated with expression of oestrous behaviour whereas the terms enriched among genes identified in analysis 2 and 3 were general processes which may facilitate proper expression of oestrous behaviour at the subsequent oestrus. Studying these genes will help to improve our understanding of the genomic regulation of oestrous behaviour, ultimately leading to better management strategies and tools to improve or monitor reproductive performance in bovines

De toekomst van het eendagskuiken

Miljoenen eendagskuikens worden jaarlijks gedood in de pluimveehouderij, omdat ze ongeschikt zijn om eieren te leggen of vleeskip te worden. Het maatschappelijk verzet daartegen klinkt steeds luider. Maar welke alternatieven zijn er? Wageningen UR Livestock Research zette ze op een rij en legde ze voor aan gewone Nederlanders