Effects of dietary fatty acids on reproduction in ruminants.
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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. (+info)
The allometry of patch selection in ruminants.
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An axiomatic feature of food consumption by animals is that intake rate and prey abundance are positively related. While this has been demonstrated rigorously for large herbivores, it is apparent from patch selection trials that grazers paradoxically tend to prefer short, sparse swards to tall, dense swards. Indeed, migratory herbivores often shift from areas of high to low sward biomass during the growing season. As nutritional quality is an inverse function of grass abundance, herbivores appear to sacrifice short-term intake for nutritional gains obtainable by eating sparse forage of higher quality. Explicit models of this trade-off suggest that individual ruminants maximize daily rates of energy gain by choosing immature swards of intermediate biomass. As body mass is related positively to both ruminant cropping rates and digestibility, there should be an allometric link between grass abundance and energy maximization, providing a tool for predicting patterns of herbivore habitat selection. We used previously published studies to develop a synthetic model of trade-offs between forage abundance and quality predicting that optimal sward biomass should scale allometrically with body size. The model predicts size-related variation in habitat selection observed in a guild of grazing ungulates in the Serengeti ecosystem. (+info)
Detection of infectious Cryptosporidium parvum oocysts in mussels (Mytilus galloprovincialis) and cockles (Cerastoderma edule).
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Infective Cryptosporidium parvum oocysts were detected in mussels (Mytilus galloprovincialis) and cockles (Cerastoderma edule) from a shellfish-producing region (Gallaecia, northwest Spain, bounded by the Atlantic Ocean) that accounts for the majority of European shellfish production. Shellfish were collected from bay sites with different degrees of organic pollution. Shellfish harboring C. parvum oocysts were recovered only from areas located near the mouths of rivers with a high density of grazing ruminants on their banks. An approximation of the parasite load of shellfish collected in positive sites indicated that each shellfish transported more than 10(3) oocysts. Recovered oocysts were infectious for neonatal mice, and PCR-restriction fragment length polymorphism analysis demonstrated a profile similar to that described for genotype C or 2 of the parasite. These results demonstrate that mussels and cockles could act as a reservoir of C. parvum infection for humans. Moreover, estuarine shellfish could be used as an indicator of river water contamination. (+info)
Fatty acid composition of lipids in immature cattle, pig and sheep oocytes with intact zona pellucida.
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Cattle, pig and sheep oocytes isolated from healthy cumulus-oocyte complexes were pooled, within species, to provide samples of immature denuded oocytes with intact zona pellucida (n = 1000 per sample) for determination of fatty acid mass and composition in total lipid, constituent phospholipid and triglyceride. Acyl-containing lipid extracts, transmethylated in the presence of a reference penta-decaenoic acid (15:0), yielded fatty acid methyl esters which were analysed by gas chromatograph. Mean (+/- SEM) fatty acid content in samples of pig oocytes (161 +/- 18 micrograms per 1000 oocytes) was greater than that in cattle (63 +/- 6 micrograms; P < 0.01) and sheep oocytes (89 +/- 7 micrograms; P < 0.05). Of 24 fatty acids detected, palmitic (16:0; 25-35%, w/w), stearic (18:0; 14-16%) and oleic (18:1n-9; 22-26%) acids were most prominent in all three species. Saturated fatty acids (mean = 45-55%, w/w) were more abundant than mono- (27-34%) or polyunsaturates (11-21%). Fatty acids of the n-6 series, notably linoleic (18:2n-6; 5-8%, w/w) and arachidonic acid (20:4n-6; 1-3%), were the most abundant polyunsaturates. Phospholipid consistently accounted for a quarter of all fatty acids in the three species, but ruminant oocytes had a lower complement of polyunsaturates (14-19%, w/w) in this fraction than pig oocytes (34%, w/w) which, for example, had a three- to fourfold greater linoleic acid content. An estimated 74 ng of fatty acid was sequestered in the triglyceride fraction of individual pig oocytes compared with 23-25 ng in ruminant oocytes (P < 0.01). It is concluded that the greater fatty acid content of pig oocytes is primarily due to more abundant triglyceride reserves. Furthermore, this species-specific difference, and that in respect of polyunsaturated fatty acid reserves, may underlie the contrasting chilling, culture and cryopreservation sensitivities of embryos derived from pig and ruminant (cattle, sheep) oocytes. (+info)
Bartonella spp. isolated from wild and domestic ruminants in North America.
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Bartonella species were isolated from 49% of 128 cattle from California and Oklahoma, 90% of 42 mule deer from California, and 15% of 100 elk from California and Oregon. Isolates from all 63 cattle, 14 deer, and 1 elk had the same polymerase chain reaction/restriction fragment length polymorphism profiles. Our findings indicate potential for inter- and intraspecies transmission among ruminants, as well as risk that these Bartonella spp. could act as zoonotic agents. (+info)
Neurocalcin-immunoreactive neurons in the mammalian dorsal root ganglia, including humans.
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Neurocalcin (NC) is a recently characterized EF-hand calcium-binding protein present in a discrete population of sensory neurons and their peripheral mechanoreceptors, but its presence in peripheral nervous system neurons other than in the rat is still unknown. The present study was designed to investigate the occurrence of NC in the dorsal root ganglia (DRG) of several mammalian species (horse, buffalo, cow, sheep, pig, dog, and rat), including humans. DRG were fixed, embedded in paraffin, and processed for immunohistochemistry using a polyclonal antibody against NC. The size of the immunoreactive neurons was measured. In all species examined, NC immunoreactivity (IR) was restricted to neurons but the percentage, as well as the size of the immunoreactive neurons, varied among different species. As a rule, small neurons (diameter <20 microm) lack NC IR. In some species (pig, dog, buffalo, cow), only the largest neurons showed IR, whereas in others (sheep, horse, rat, and humans) they covered the entire range of neuron sizes. The pattern of immunostaining was cytoplasmic, although in some species (cow and buffalo), it formed a peripheral "ring." The present results demonstrate that mammalian DRG contain a subpopulation of NC-positive neurons, which varies from one species to another. Based on the neuron size, the possible function of the NC-containing neurons is discussed. (+info)
Effects of planting density and processing method on laboratory characteristics of grain sorghum for ruminants.
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Grain sorghum grown in 38-cm (high-density) or 76-cm rows (normal-density) was steam-flaked, harvested as high-moisture grain followed by rolling and ensiling, or dry-rolled. Chemical composition, enzymatic starch availability, CP insolubility, and IVDMD in a reduced-strength buffer were evaluated. High-density planting increased (P < .10) OM and starch concentration and decreased (P < .0001) CP concentration but did not affect (P > .10) P concentration, enzymatic starch availability, or CP insolubility. High-density planting resulted in lower (P < .10) in vitro ruminal culture pH at 6, 12, and 18 h of incubation when grain sorghum was processed by steam flaking, and lower (P < .10) IVDMD at 6, 12, and 18 h of digestion when grain sorghum was processed by dry rolling. Steam flaking decreased (P < .10) CP concentration and solubility and increased (P < .10) OM concentration. High-moisture ensiling decreased (P < .10) the insolubility of CP but did not otherwise seem to alter the chemical composition of grain sorghum relative to dry rolling. Starch was more available (P < .10), and DM was digested more rapidly and extensively (P < .10) in vitro, in steam-flaked sorghum followed by high-moisture sorghum. Based on these data, it seems that planting density primarily affected chemical composition of grain sorghum, whereas processing primarily affected CP insolubility and rate and extent of starch fermentation. (+info)
Consistency of SINE insertion topology and flanking sequence tree: quantifying relationships among cetartiodactyls.
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Short interspersed nuclear elements (SINEs) have been used to generate unambiguous phylogenetic topologies relating eukaryotic taxa. The irreversible nature of SINE retroposition is supported by a large body of comparative genome data and is a fundamental assumption inherent in the value of this qualitative method of inference. Here, we assess the key assumption of unidirectional SINE insertion by comparing the SINE insertion-derived topology and the phylogenetic tree based on seven independent loci of five taxa in the order Cetartiodactyla (Cetacea + Artiodactyla). The data sets and analyses were largely independent, but the loci were, by definition, linked, and thus their consistency supported an irreversible pattern of SINE retroposition. Moreover, our analyses of the flanking sequences provided estimates of divergence times among cetartiodactyl lineages unavailable from SINE insertion analysis alone. Unexpected rate heterogeneity among sites of SINE-flanking sequences and other noncoding DNA sequences were observed. Sequence simulations suggest that this rate heterogeneity may be an artifact resulting from the inaccuracies of the substitution model used. (+info)