Effects of supplemental vitamin A or beta-carotene during the dry period and early lactation on udder health.

Effects of vitamin A or beta-carotene supplementation during the dry period and early lactation on the frequency of new intramammary infection and clinical mastitis and on SCC and milk yield were examined. Eighty-two Holstein cows were randomly assigned to one of three groups: 1) 50,000 IU/d of vitamin A per cow (approximately equivalent to 1978 NRC recommended daily intake for dairy cows); 2) 170,000 IU/d of vitamin A per cow; or 3) 50,000 IU/d of vitamin A plus 300 mg of beta-carotene per cow. Cows were supplemented during the 2 wk before drying off, throughout the dry period, and for the first 6 wk of lactation. Concentrations of serum vitamin A did not differ among treatment groups but tended to decrease for all treatment groups from 14 d before drying off to calving. After calving, serum vitamin A tended to increase in all groups through wk 6 of lactation. Serum beta-carotene tended to be higher in beta-carotene-supplemented cows at dry-off, in the early dry period, and again during lactation. Serum beta-carotene decreased sharply in all groups during the prepartum period. The frequency of clinical mastitis and of new intramammary infection during the dry period, near parturition, and for the first 6 wk of lactation did not differ among treatment groups. The percentage of quarters newly infected over the entire trial was 26.8 in the control, 25.0 in the high vitamin A, and 30.6 in the beta-carotene group. Pathogens isolated most frequently were coagulase-negative staphylococci, streptococci other than Streptococcus agalactiae, and coliforms.(ABSTRACT TRUNCATED AT 250 WORDS)     

Calcium salts of fatty acids in diets that differ in neutral detergent fiber: effect on lactation performance and nutrient digestibility

Total mixed rations containing 31 or 25% NDF were supplemented with 0 or .5 kg/cow per d Ca salts of fatty acids to study the effect of adding Ca salts of fatty acids to diets that differed in NDF content. Rations were fed for ad libitum intake to 12 early to midlactation Holstein cows in a replicated 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments. No significant interactions were detected between Ca salts of fatty acids and ration NDF content. The Ca salts of fatty acids lowered milk protein percentage. Cows increased yield of milk, fat, and 4% FCM when they were fed Ca salts of fatty acids. Intake of DM and NE1 increased when NDF was 25% rather than 31% of the total mixed ration. Milk from cows fed 25% NDF contained less fat and more protein. Yields of milk, fat, protein, and 4% FCM increased when diets contained 25% NDF. Conversion of DM intake to 4% FCM, however, decreased. Apparent digestibility of DM increased when diets contained 25% compared with 31% NDF. In this study, Ca salts of fatty acids increased yields of milk and 4% FCM, regardless of ration NDF content. Production increased but efficiency decreased when diets contained 25% vs. 31% NDF.     

Initiation of parturition in dairy cows with dexamethasone. II. Response to dexamethasone in combination with estradiol benzoate.

Parturition was initiated in 26 Holstein cows given dexamethasone (4.4 mg/100 kg body weight) in combination with 25 mg estradiol benzoate intramuscularly at day 273 of gestation. Parturition occurred at 40.8 +/- 9.6 h after injection. Twenty-six control cows had an average gestation length of 281.5 days. Calving difficulty was not different although birth weight of calves was 2.5 kg less for induced cows compared with control cows. Severity of udder edema did not differ between groups. Average daily milk production for the first 9 wk of lactation was lower (24.2 versus 27.7 kg) from induced than control groups. Incidence of retained placental membranes was 50 and 4% for induced and control cows. Serum estrogens were lower (290 versus 601 pg/ml) in induced than in control cows 2 days prior to parturition. Groups did not differ inserum calcium, phosphorus, magnesium, days to first heat, days to first breeding, days to conception, or in fat, protein, and total solids content of colostrum. Casein in colostrum of induced cows was lower. Results of California Mastitis Tests at 15 and 30 days postpartum were similar.     

AN APPROACH TO THE ESTIMATION OF BREWING QUALITY IN BARLEY AND MALT

Methods of assessing the brewing qualities of new varieties are reviewed. A new method for making this assessment is proposed. This is ideally a three-step process but it would be possible to eliminate the third, costly, step without severe loss of effectiveness. The use of the new method is illustrated by reference to trials using 251 samples from recent trials in France.     

THE INFLUENCE OF GRAIN COMPONENTS ON INFUSION MASH PERFORMANCE

The conversion of malt starch depends on the availability of water in the mash. At liquor to grist ratios of 3:1 or more, conversion is independent of the quantity of water present. At liquor to grist ratios of 2:1 or lower the amount of starch converted is proportional to the amount of water present. The presence of other water-binding molecules, such as maltose, beta-glucan, or pentosan increases the water dependence of the mash. The presence of protein per se does not affect water availability. However, since the starch content of grain is inversely proportional to the nitrogen level, low nitrogen malts require more water for complete conversion than those with higher nitrogen. The effective gelatinization of an isothermal adjunct mash may also depend on the amount of water available.     

A National Web-Based Survey of Sunscreen Products as a Tool for Industry Self-Regulation, Consumer Awareness Campaigns and Marketing

The objective of the work was to test a web-based tool in the collection and presentation of data for our regular sunscreen surveys and to develop, test and conduct a web-based survey of sunscreen products, with instant data reporting. After the Photobiology Laboratory at MEDUNSA was approached by SurveyIT to pilot a new web-based data collection and reporting tool, companies were contacted via e-mail and invited to visit a secure web-based site to complete the provided questionnaire. Data collection and processing were greatly simplified by the new approach. The survey gleaned responses from 18 companies on 31 brands with a total of 110 primary sunscreen products. The data revealed a reduction in the number of companies marketing sunscreens in South Africa compared with the previous year, despite an increase in the volume of sunscreen sales. Ninety-eight percent of the products were claimed to be in vivo SPF tested. Fifty-seven percent of the products had undergone in vitro SPF testing for determination of their UVA protection. Fifty-one percent of the products were claimed to be water-resistant. Octyl methoxycinnamate was the most popular UV filter (88% of products), followed by benzophenone-3 (60%). Butyl methoxydibenzoylmethane was in 52% of the products and surprisingly only 29% of the products contained titanium dioxide. The major conclusions are that the data collection tool was a success and that sunscreens are becoming more widely used and more thoroughly tested in South Africa.     

Addition of sodium bicarbonate to rations of postpartum dairy cows: physiological and metabolic effects

Sodium bicarbonate was added to complete mixed rations to characterize physiological, metabolic, and ruminal changes immediately postpartum when dairy cows are switched abruptly from a low energy ration prepartum to a high energy ration postpartum. Twelve Holstein cows were paired and assigned randomly to either a control or buffered ration containing .8% sodium bicarbonate. Rations consisted of 50% corn silage:50% concentrate. All All cows were fed a similar dry cow ration for a minimum of 7 days prepartum and experimental rations for 2 wk beginning at parturition. Blood, feces, and urine were sampled on days 1, 2, 4, 7, 10, and 14 postpartum. Rumen fluid was sampled on days 7 and 14. Dry matter intake and milk production were 2.75% of body weight and 30.3 kg/day for cows fed buffer and 2.49% and 27.6 kg/day for cows fed control. Higher partial pressure of carbon dioxide and base excess in blood in cows fed buffer existed on days 2 and 4 postpartum than for cows fed the control ration. Cows fed buffer had higher concentrations of ruminal ammonia than cows fed control. This difference was less pronounced in blood urea nitrogen and urinary ammonia. Urine pH was higher for cows fed buffer than for control. Addition of sodium bicarbonate improved the acid-base status after abrupt change of ration and may be associated with increased dry matter intake and improved ration adaptation. Concentrations of most minerals and metabolites in blood serum did not differ between rations.     

Multilayered Ge/SiGe Material in Microfabricated Thermoelectric Modules

Results for low dimensional p-type Ge/SiGe superlattices with Ge quantum wells of 3.43 nm are presented. A range of microfabricated test structures have been developed to characterise the cross-plane electrical and thermal properties of the Ge/SiGe heterostructures. These superlattices were directly grown on 100-mm-diameter silicon wafers by a chemical vapour deposition growth system with rates up to 6 nm/s. Quantum well and quantum mechanical tunnel barriers with dimensions down to \(\sim1\) nm have been designed, grown and tested; they demonstrate a ZT of 0.08 ± 0.011 and power factor of 1.34 ± 0.15 m W m^?1 K^?2 at 300 K. A complete microfabricated module using indium bump-bonding is reported together with preliminary results on unoptimised material and leg dimensions. Routes to optimise the material and modules are discussed.     

Distinct T cell receptor signaling requirements for perforin- or FasL-mediated cytotoxicity

A diverse array of signals are generated in a cytotoxic T lymphocyte (CTL) after the T cell receptor (TCR) engages the class I major histocompatibility complex (MHC) peptide complex. These signals result in a multitude of CTL effector functions, including cellular cytotoxicity, cell surface receptor expression, and cytokine secretion. We have examined signaling through the TCR in a wild type CD8+, MHC-restricted, antigen-specific CTL clone, 14-7, and its interleukin 2-dependent variant clone 14-7FD. We report here that 14-7FD is unable to kill via the perforin mechanism of killing, yet is able to kill via the Fas ligand/Fas mechanism and secrete interferon-gamma in an antigen-specific manner. 14-7FD has cytolytic granules that contain perforin and serine esterases, which are secreted after phorbol ester and Ca2+ ionophore treatment. Lastly, to investigate which TCR signaling requirements were operational in 14-7FD, we examined TCR-triggered intracellular Ca2+ mobilization in the two clones. After TCR engagement, 14-7FD failed to mobilize intracellular Ca2+, which may be the cause for its inability to trigger the perforin/granule exocytosis mechanism of killing. These results indicate that the signal transduction events that trigger perforin killing and the signaling requirements to induce FasL expression are distinct. We hypothesize that these two distinct TCR signal transduction requirements allow for separate activation of these two mechanisms of killing relating to their role in eradication of infected cells or regulation of immune responses.     

Flow control in microdevices using thermally responsive triblock copolymers

Active and passive microflow control has been demonstrated using gel formation by dilute aqueous solutions of triblock copolymers at elevated temperatures. Solutions of a poly(ethylene oxide)/sub 106/-poly(propylene oxide)/sub 70/-poly(ethylene oxide)/sub 106/ polymer, which has the trade name Pluronic/spl reg/ F127, have been used as a sample system. Flow in a microchannel has been stopped in less than 33 ms by introducing heat with an integrated electric heater. Viscous heating under high shear rates also induces gel formation, which has been used for passive automated flow control in a microchannel.