Drinking behavior of lactating dairy cows and prediction of their water intake

The water intake of 41 lactating dairy cows managed according to current dairy farm practices was individually and continuously monitored to 1) investigate drinking behavior and 2) determine factors affecting water intake. The cows were housed in a free-stall barn and fed once daily with a corn silage and concentrate-based total mixed ration (48% dry matter content; 20.6 ± 3.3 kg/d of dry matter intake). Cows were milked twice daily, with a yield of 26.5 ± 5.9 kg/d. The daily free water intake (FWI) was 83.6 ± 17.1 L, achieved during 7.3 ± 2.8 drinking bouts. The drinking bout water intake was 12.9 ± 5.0 L. Almost three-fourths of the FWI occurred during working hours (0600 to 1900 h). Consumption peaks corresponded to feeding and milking times. More than one quarter of the daily FWI was met during the 2 h after each milking. About 75% of the present cows visited the watering point at least once during the 2 h after the evening milking. It is probable that drinking behavior evolved with lactation, but further studies are required to identify the relationship between lactation stage and drinking behavior. The most relevant factors affecting the daily FWI of lactating cows were best combined according to the following predictive equation: (R² = 0.45; n = 41 cows, n = 1,837): FWI, L/d = 1.53 × dry matter intake (kg/d) + 1.33 × milk yield (kg/d) + 0.89 × dry matter content (%) + 0.57 × minimum temperature (°C) - 0.30 × rainfall (mm/d) - 25.65. The results obtained using these equations were in agreement with the equations developed by other researchers.     

Short communication: Effect of subclinical mastitis on proteolysis in ovine milk

The aim of this work was to evaluate the effect of intramammary infection (IMI) on the endogenous proteolysis of milk. Four control checks were carried out in the half-udder milk of 10 ewes that acquired unilateral subclinical mastitis. Two of these checks were conducted before the infection was established and 2 after. Ten healthy ewes were tested as a control group. The presence of a subclinical IMI involved an increase of the products of casein hydrolysis, the proteose-peptone (p-p) fraction and minor (m) caseins, and a decrease of β-casein. As a result, a significant increase in the proteolysis index (PI), calculated as the ratio of m-casein to the sum of caseins (α + β + κ), took place. α-Casein and κ-casein were not significantly affected by IMI. Correlations confirmed the scenario: log₁₀ of somatic cell count (SCC) was positively correlated with p-p content and negatively with β-casein, whereas log₁₀ SCC was not correlated with α-casein or κ-casein. On the other hand, p-p content was positively correlated with m-casein and PI and negatively with β-casein, but no correlation was detected between p-p content and α- or κ-casein. Furthermore, between casein fractions, m-casein was only significantly correlated with β-casein. These results suggest that use of indices of proteolysis of caseins such as p-p, m-casein, and PI, could be applied together with SCC to evaluate the cheese-making quality of milk.     

Ignition mechanism of the Zr/PbCrO4 pyrotechnic mixture in presence of an oxidizing atmosphere

In presence of oxygen, the Zr/PbCrO₄ (60%/40%) solid mixture exhibits a high amplitude exothermal reaction at low temperature (before reaching the oxidant decomposition temperature). We assume that the reaction is entertained by the air oxygen which continuously diffuses into the mixture pores. The solid-phase diffusion of oxygen through a zircon layer seems to constitute the limiting step of the reaction. To verify this assumption, a model allowing for diffusion in a protective oxide is developed. The results obtained with this model correspond to the tests for an apparent energy diffusion value varying between 130 kJ/mol and 170 kJ/mol. A value of 130 kJ/mol corresponds to the migration energy of the anionic gaps in a porous zircon layer. The evolution of the apparent diffusion energy can be attributed to the formation energy of crystalline defects (in particular anionic gaps).     

Psychological characteristics of South African street children

Research has shown that no treatment program designed for street children can succeed unless the community is prepared to respect, protect, and provide opportunities for them (Tacon, cited in Schurink & Rip, 1993). Unfortunately, these children are abused in many parts of the world (Aptekar, 1994). This paper investigates why the general public, as well as those charged with enforcing the law, often treat street children with scorn and hostility.     

Should diastasis recti be corrected?

From theoretical considerations animals with a higher protein-fat ratio in the body should have a higher maintenance energy requirement (MEm). The literature on this problem shows a non-uniform picture with deviating results. From the results of a series of experiments it is possible to compare the heat production (HP) of male and female animals of the Vietnamese Sway-back breed pigs which vary quite widely in their body composition. The protein-fat ratio was 1.2 for the male and 0.2 for the female animals. In the experiments 4 male and 4 female animals in the live weight range of 20-33 kg and 33-42 kg, respectively, were involved. The HP measurements were carried out in climatized respiration chambers on two levels of energy intake at ambient temperatures of 6 degrees C, 12 degrees C, 18 degrees C, 24 degrees C, 30 degrees C, and 35 degrees C. The dependence of HP on the ambient temperature has been described by a cubic regression function. Thermoneutral temperatures are lower in the female animals caused by the better insulation effect of the backfat. The difference in HP which was expected by the large difference in body composition, was not found. The absolute protein mass determined the correlation to HP. Certainly the difference increased after lowering the ambient temperature. The influence of different factors on HP is discussed.     

Computational studies of the gramicidin channel

Ion channels are highly specific membrane-spanning protein structures which serve to facilitate the passage of selected ions across the lipid barrier. In the past decade, molecular dynamics simulations based on atomic models and realistic microscopic interactions with explicit solvent and membrane lipids have been used to gain insight into the function of these complex systems. These calculations have considerably expanded our view of ion permeation at the microscopic level. This Account will mainly focus on computational studies of the gramicidin A channel, one of the simplest and best characterized molecular pore.     

Alternative cathodes based on iron phthalocyanine catalysts for mini- or micro-DMFC working at room temperature

Iron phthalocyanine based cathodes were prepared either by dispersion of FePc on carbon or by electropolymerization of aniline in presence of FeTsPc. The macrocycles based cathodes were compared to a classical commercial Pt/C cathode in a standard three-electrode electrochemical cell and under DMFC conditions at room temperature. It was shown that the molecular dispersion of FeTsPc into a PAni film greatly enhances the activity of the macrocycle catalyst towards oxygen reduction reaction (ORR). But, in the same time, the stability under DMFC conditions is drastically decreased compared to the stability obtained with a FePc/C electrode. It was suggested that this instability of the catalytic film was rather due to the release of the FeTsPc from the polymer than to the destruction of the macrocycle active centre. Even if iron phthalocyanine catalysts display total tolerance to methanol when the anode is fed with a 5 M methanol solution, the comparison between a PAni-FeTsPc/C cathode and a Pt/C cathode in DMFC working conditions is in favor of the Pt/C cathode, in term of maximum achieved power density. However, the ratio (platinum atoms per cm²/number of FeTsPc molecules per cm²) is close to 100, which allows to be optimistic for further enhancement of activity of polymer-FeTsPc electrodes. It was suggested that researches to develop new electron conductive polymers stable under oxidative environment and with a high doping capacity could be a direction to use platinum alternative cathode catalysts in DMFC technology.     

Modélisation de la cinétique de biodégradation de phénol par granules aérobies

This work describes a model of the biodegradation of phenol carried out by aerobic granules. These granules were obtained by culturing an activated sludge supernatant in a sequencing batch reactor fed with a synthetic waste water and subsequently, by acclimation to phenol (100 mg/L). The kinetics of phenol biodegradation by the aerobic granules was investigated over a wide range of initial phenol concentrations (40–1112 mg/L) in shake‐flask cultures. A Haldane‐type model was adjusted to the experimental results, which depicts successfully the phenol biodegradation profiles in the entire range of initial concentrations studied by using only one set of parameters. It is our view that the proposed model could contribute to the knowledge about the ability of aerobic granular systems to biodegrade toxic, inhibitory compounds such as phenol.     

The Study of a 231 French Patient Cohort Significantly Extends the Mutational Spectrum of the Two Major Usher Genes MYO7A and USH2A

Usher syndrome is an autosomal recessive disorder characterized by congenital hearing loss combined with retinitis pigmentosa, and in some cases, vestibular areflexia. Three clinical subtypes are distinguished, and MYO7A and USH2A represent the two major causal genes involved in Usher type I, the most severe form, and type II, the most frequent form, respectively. Massively parallel sequencing was performed on a cohort of patients in the context of a molecular diagnosis to confirm clinical suspicion of Usher syndrome. We report here 231 pathogenic MYO7A and USH2A genotypes identified in 73 Usher type I and 158 Usher type II patients. Furthermore, we present the ACMG classification of the variants, which comprise all types. Among them, 68 have not been previously reported in the literature, including 12 missense and 16 splice variants. We also report a new deep intronic variant in USH2A. Despite the important number of molecular studies published on these two genes, we show that during the course of routine genetic diagnosis, undescribed variants continue to be identified at a high rate. This is particularly pertinent in the current era, where therapeutic strategies based on DNA or RNA technologies are being developed.     

Continuous fixed bed biosorption of Cu2+ ions: application of a simple two parameter mathematical model

Biomass from two fungi of the Mucorales order, laboratory cultured and immobilised Rhizopus arrhizus, and industrial waste Mucor miehei, was tested for capacity to adsorb copper from solution in batch and continuous‐flow column systems. Maximum uptake levels were c 400 and 300 mmol g⁻¹ (dry weight) respectively. Immobilisation of Rhizopus arrhizus in polyvinyl formal to cell loadings of 60% (w/w) did not diminish metal uptake levels. In continuous‐flow columns both biosorbents adsorbed copper to levels equal or approaching the batch uptake values. Column breakthrough curves were fitted to a two parameter model and each of the parameters, σ and t₀ , were linearly correlated with column operating parameters. Predicted breakthrough curves agreed closely with experimental values. © 1999 Society of Chemical Industry