Sorption of cadmium on suspended matter under estuarine conditions; competition and complexation with major sea-water ions

Sorption of Cd at low concentrations onto river Rhine suspended matter was examined in terms of sorption rate, reversibility and factors such as competition and complexation with major inorganic sea-water ions. More than 90% of the final amount of Cd is sorbed within the first few hours. Desorption experiments show that the process is virtually reversible. In experiments with diluted sea water the sorption of Cd strongly decreases even at low salinity. Sorption isotherms show that the sorption of Cd in NaNO₃ solutions is regulated by the free Cd²⁺ activity. In a Ca(NO₃)₂ environment the Cd sorption decreases with increasing Ca²⁺ concentrations, which implies competition between Ca²⁺ and Cd²⁺ for the different sorption sites. In different electrolyte solutions of similar ionic strength the sorption of Cd decreases in the solution order NaNO₃ > NaCl > NaCl+MgCl₂+CaCl₂ > diluted sea water. Although inorganic speciation calculations show that even at low salinities dissolved Cd is dominated by Cd-chloro complexes, chloride accounts for only about one third of the increased mobility of Cd. As a result of addition of Ca²⁺ and Mg²⁺ the sorption capacity of suspended matter for Cd is further reduced by a factor three.     

Cow effects and estimation of success of first and following inseminations in Dutch dairy cows

The objective of this research was to determine the contribution of cow factors to the probability of successful insemination accounting for the serial number of inseminations in analysis. The investigation was performed with 101,297 insemination records in 51,525 lactations of different cows from 1368 herds obtained from the Dutch milk production recording database. Cows that had a first insemination (AI) between 40 and 150 days post-partum with one or more inseminations (≤6 inseminations) were selected. An insemination was defined successful when not followed by another insemination and when the cow calved between 267 and 295 days after insemination, or when the cow was culled between 135 and 295 days after the last insemination. Breed, parity, days in milk, lactation curve characteristics, milk production traits, moment of AI related to peak milk yield time (before or after peak milk yield), the last calf (female, male, twin or stillbirth) and season of insemination were selected as independent parameters for a model with successful rate of insemination as dependent parameter. A multivariable logistic regression model was used within cow and farm as a random effect. The probability of successful insemination was the highest in the first insemination and decreased in the following inseminations. However, the success rate of all inseminations increased in a later stage of lactation. The improvement in the successful inseminations in a later stage of lactation was better in multiparous cows than in first parity cows. Insemination in summer and before peak milk yield time reduced the success of insemination. The success rate was the lowest in 100% Holstein Friesian cows compared with other breeds and was the highest when the last calf was a female calf compared to a male calf, twin or stillbirth. In conclusion, the success of first and following inseminations depended on parity, breed, season of insemination, last calf status, daily milk yield at insemination date, serial insemination number and days in milk at insemination date.     

The effect of two different routes of administration of oxytocin on peripheral plasma prostaglandin F(2α) metabolite levels in early post-partum dairy cows

Various parenteral treatment forms of oxytocin, as often used under praxis circumstances, may act differently on contractility of the uterus during the first days of the puerperium. Various patterns of such induced uterotonic responses may lead to alterations in the emptying characteristics of the uterine lumen, thus influencing, as a late consequence, the process of involution. Therefore, this study was designed to test whether two different parenteral administration forms of oxytocin induce changes in peripheral plasma concentrations of 15-ketodihydro-prostaglandin F(2α) (PGF(2α) metabolite) in early post-partum cows. Between 13 and 15 h after uncomplicated calving, healthy dairy cows without retained foetal membranes were treated with 50 IU oxytocin, either intramuscularly (OT-IM group; n = 15) or intravenously (OT-IV group; n = 16). Saline solution was administered intramuscularly as controls (CON group; n = 15). Jugular blood samples were taken at 10-min intervals from 1 h before to 2 h after treatment. Plasma PGF(2α) metabolite levels were measured by radioimmunoassay. No significant differences in peripheral plasma PGF(2α) metabolite concentrations occurred in the OT-IM and CON groups, but mean values significantly increased in the OT-IV group, peaking at 20 min after treatment and reaching pre-treatment baseline values again at 120 min. Although the source of prostaglandins was not investigated in this study, our results suggest that exogenous oxytocin may enhance secretion of prostaglandins by the uterus during the first day after normal calving. These prostaglandins might contribute, by an endocrine or paracrine route, to the stimulation of myometrial contractility when exogenous oxytocin is given during this early post-partum stage.     

Uterine Responses to Exogenous Oxytocin Before and After Pre-partum Luteolysis in the Cow

The aim of this study was to test the functional status of uterine oxytocin receptors in cows in vivo around parturition. The animals received consecutive, intra‐arterial injections of 800, 1600 and 3200 mU of oxytocin at three different stages: during late gestation (days 260–274), at 12 h and at 24 h after intramuscular injection of a prostaglandin F_2α analogue at day 275 to induce parturition. Cows (n=6) had been provided with myometrial electrodes and a catheter had been installed in the aorta and in a branch of the uterine vein (UV). Regular blood samples were obtained from the UV from 5 min before until 45 min after each oxytocin injection to measure plasma levels of prostaglandin F_2α (PGF_2α) and oxytocin. Uterine electromyographic (EMG) activity was registered continuously during each experiment. The increase of oxytocin levels in UV plasma after intra‐arterial injections was dose dependent (p < 0.02). Pre‐ and post treatment oxytocin levels at 24 h after induction of parturition were significantly increased (p=0.0313). Both during late pregnancy and at 12 h after induction of parturition, oxytocin caused a significant increase in EMG activity (p=0.022). After the 3200 mU dose the increase was significantly higher than with the other 2 doses (p=0.004). After each dose, EMG activity returned to baseline levels within some 15 min. At 24 h after induction of parturition, the pre‐treatment level of EMG activity had increased. Doses of 800 mU and 1600 mU of oxytocin produced a significant (p=0.022) increment of EMG activity, which was of the same magnitude as during the preceding stages; after 3200 mU of oxytocin the response was significantly higher than before (p=0.008). No significant increases of PGF_2α levels in UV plasma could be measured after oxytocin injections at any of the three stages. It is concluded that the myometrium of the pregnant cow responds in vivo to physiological doses of oxytocin. At 24 h after induction of parturition, when luteolysis has occurred and a parturient pattern of parturient myometrial activity has already started to develop, the response is enhanced. Physiological doses of oxytocin did not evoke a spurt release of PGF_2α in uterine venous blood during the peripartal period.     

Weathering,Biomass Production and Groundwater Chemistry in an Area of Dominant Anthropogenic Influence,the Chaves-Vila Pouca de Aguiar Region,North of Portugal

Using a combination of a grouping algorithm and a geochemical mole balance algorithm, we could identify and quantify the contributions made by water-rock and water-biomass interactions to the composition of shallow groundwaters in northern Portugal, in an area with a sizable anthropogenic input (the Chaves-Vila Pouca de Aguiar region). The first algorithm, based on the mathematical concept of equivalent relations, allows for the grouping of water samples with similar chemistries. The second algorithm, which uses the stoichiometries and mole/charge balances in weathering reactions and biological processes, provides the possibility to relate the average chemistry of each identified group to water-mineral and water-biomass interactions. This algorithm hinges on ratios of dissolved silica and bicarbonate, constituents considered to be derived only from chemical weathering and biomass production. Background information on the petrology, mineralogy and chemistry of bedrocks and soils, on climatic differences, on the history of deforestation and reforestation of the study area, and on the application and composition of fertilizers and manure, was used to identify the most realistic weathering reactions and biological processes which contribute to the water chemistry. The concentrations of chloride, sulphate and nitrate were considered to represent sources other than chemical weathering or biomass changes, like cyclic salts, fertilizers and manure. Despite the high background concentrations derived from such sources, we were able to quantify the contributions of the identified weathering reactions and botanical uptake to the groundwater composition. The spatial distributions of the various groundwater groups shows a good correlation with the geology, land use and climatic differences in the area.