Reduced Water Intake Research Articles

Associative learning contributes to the increased water intake observed after daily injections of angiotensin II

Daily injections of angiotensin II (AngII) cause a progressive increase of water intake that resembles a classically ascribed non-associative sensitization. Consistent with the presumption that the observed increase in intake was sensitization, we hypothesized that it resulted from a pharmacological interaction between AngII and its receptor. To test this hypothesis, and remove the influence of drinking itself, we implemented a delay in water access after injection of AngII (icv) on four consecutive ‘induction days,’ and then measured intake on the next day (‘test day’) when rats were allowed to drink immediately after AngII. The delay in water access effectively reduced water intake on the four induction days, and rats with longer delays in access drank less on the test day than did rats allowed to drink immediately after AngII on the induction days. Additional experiments ruled out a role for a conditioned drinking response to the injection alone, and demonstrated a lack of conditioned appetition after pairing injections of AngII with water given by intragastric catheter. Taken together, these findings suggest that the increased drinking observed after daily injections of AngII is a conditioned appetition after repeated pairings of AngII and water intake. We further conclude that repeated stimulation of the AngII receptor alone is not sufficient to drive appetition.

Pathophysiologic insight into MesoAmerican nephropathy.

Mesoamerican nephropathy (MeN) is an emerging pathophysiological entity of Chronic kidney desease (CKD) not related to traditional risk factors (diabetes and hypertension) that have caused thousands of deaths in Central America, mainly in sugarcane workers. The focus of this review is to discuss the risk factors and probable mechanisms involved in the initiation and progression of this devastating disease. Frequent episodes of subclinical Acute kidney injury caused by repetitive heat stress, dehydration, and strenuous work have been regarded as the main risk factors for MeN. The combination of them chronically activates vasopressin, renin angiotensin aldosterone system, and polyol-fructokinase pathway in the kidney. Also, subclinical rhabdomyolysis compound the framework of the disease by exacerbating systemic inflammation and inducing uricosuria. Exposure to nephrotoxins, high fructose intake, and use of NSAIDs could also contribute to further accelerating the progression of the disease. The evidence supports the notion that recurrent cycles of heat stress, dehydration, and strenuous work may cause CKD. The chronic activation of such mechanisms likely occurs in other conditions of reduced water intake and probably explains why the current management of CKD has not been effective to revert or halt the progression to end-stage CKD.

Amylin receptor activation in the ventral tegmental area reduces motivated ingestive behavior

Amylin is produced in the pancreas and the brain, and acts centrally to reduce feeding and body weight. Recent data show that amylin can act in the ventral tegmental area (VTA) to reduce palatable food intake and promote negative energy balance, but the behavioral mechanisms by which these effects occur are not fully understood. The ability of VTA amylin signaling to reduce intake of specific palatable macronutrients (fat or carbohydrate) was tested in rats in several paradigms, including one-bottle acceptance tests, two-bottle choice tests, and a free-choice diet. Data show that VTA amylin receptor activation with the amylin receptor agonist salmon calcitonin (sCT) preferentially and potently reduces intake of fat, with more variable suppression of sucrose intake. Intake of a non-nutritive sweetener is also decreased by intra-VTA administration of sCT. As several feeding-related signals that act in the mesolimbic system also impact motivated behaviors besides feeding, we tested the hypothesis that the suppressive effects of amylin signaling in the VTA extend to other motivationally relevant stimuli. Results show that intra-VTA sCT reduces water intake in response to central administration of the dipsogenic peptide angiotensin II, but has no effect on ad libitum water intake in the absence of food. Importantly, open field and social interaction studies show that VTA amylin signaling does not produce anxiety-like behaviors. Collectively, these findings reveal a novel ability of VTA amylin receptor activation to alter palatable macronutrient intake, and also demonstrate a broader role of VTA amylin signaling for the control of motivated ingestive behaviors beyond feeding.

Reduced water intake deteriorates glucose regulation in patients with type 2 diabetes

Epidemiological research has demonstrated that low daily total water intake is associated with increased diagnosis of hyperglycemia. Possible mechanisms for this increase include hormones related to the hypothalamic pituitary axis as well as the renin-angiotensin-aldosterone system (RAAS). Therefore, the hypothesis of the present study was that acute low water intake would result in differential hormonal profiles and thus impaired blood glucose regulation during an oral glucose tolerance test (OGTT) in people with type 2 diabetes mellitus (T2DM). Nine men (53 ± 9 years, 30.0 ± 4.3 m∙kg−2, 32% ± 6% body fat) diagnosed with T2DM completed OGTTs in euhydrated (EUH) and hypohydrated (HYP) states in counterbalanced order. Water restriction led to hypohydration of −1.6% of body weight, with elevated plasma (EUH: 288 ± 4, HYP: 298 ± 6 mOsm·kg−1; P < .05) and urine (EUH: 512 ± 185, HYP: 994 ± 415 mOsm·kg−1; P < .05) osmolality. There was a significant main effect of condition for serum glucose (at time 0 minute 9.5 ± 4.2 vs 10.4 ± 4.4 mmol∙L−1 and at time 120 minutes 19.1 ± 4.8 vs 21.0 ± 4.1 mmol∙L−1 for EUH and HYP, respectively; P < .001) but not insulin (mean difference between EUH and HYP −12.1 ± 44.9 pmol∙L−1, P = .390). An interaction between time and condition was observed for cortisol: decrease from minute 0 to 120 in EUH (−85.3 ± 82.1 nmol∙L−1) vs HYP (−25.0 ± 43.0 nmol∙L−1; P = .017). No differences between conditions were found within RAAS-related hormones. Therefore, we can conclude that 3 days of low total water intake in people with T2DM acutely impairs blood glucose response during an OGTT via cortisol but not RAAS-mediated glucose regulation.

Adropin Is a Key Mediator of Hypoxia Induced Anti-Dipsogenic Effects via TRPV4-CamKK-AMPK Signaling in the Circumventricular Organs of Rats.

Water intake reduction (anti-dipsogenic effects) under hypoxia has been well established, but the underlying reason remains unknown. Our previous report indicated that activated TRPV4 neurons in SFO are associated with anti-dipsogenic effects under hypoxia. Although low partial pressure of blood oxygen directly activates TRPV4, humoral factors could also be involved. In the present study, we hypothesize that adropin, a new endogenous peptide hormone, was rapidly increased (serum and brain) concomitant with reduced water intake in early hypoxia. Also, the nuclear expression of c-Fos, a marker for neuronal activation, related to water-consumption (SFO and MnPO) was inhibited. These effects were mitigated by a scavenger, rat adropin neutralizing antibody, which effectively neutralized adropin under hypoxia. Interestingly, injection of recombinant adropin in the third ventricle of the rats also triggered anti-dipsogenic effects and reduced c-Fos positive cells in SFO, but these effects were absent when TRPV4 was knocked down by shRNA. Moreover, adropin-activated CamKK-AMPK signaling related to TRPV4 calcium channel in SFO in normoxia. These results revealed that dissociative adropin was elevated in acute hypoxia, which was responsible for anti-dipsogenic effects by altering TRPV4-CamKK-AMPK signaling in SFO.

Decreased home cage movement and oromotor impairments in adult Fmr1-KO mice.

Fragile X syndrome (FXS) is a common inherited disorder that significantly impacts family and patient day-to-day living across the entire life span. The childhood and adolescent behavioral consequences of FXS are well appreciated. However, there are significantly fewer studies (except those examining psychiatric comorbidities) assessing behavioral phenotypes seen in adults with FXS. Mice engineered with a genetic lesion of fragile X mental retardation 1 (Fmr1) recapitulate important molecular and neuroanatomical characteristics of FXS, and provide a means to evaluate adult behavioral phenotypes associated with FXS. We give the first description of baseline behaviors including feeding, drinking, movement and their circadian rhythms; all observed over 16 consecutive days following extensive environmental habituation in adult Fmr1-KO mutant mice. We find no genotypic changes in mouse food ingestion, feeding patterns, metabolism or circadian patterns of movement, feeding and drinking. After habituation, Fmr1-KO mice show significantly less daily movement during their active phase (the dark cycle). However, Fmr1-KO mice have more bouts of activity during the light cycle compared with wild types. In addition, Fmr1-KO mice show significantly less daily water ingestion during the circadian dark cycle, and this reduction in water intake is accompanied by a decrease in the amount of water ingested per lick. The observed water ingestion and circadian phenotypes noted in Fmr1-KO mice recapitulate known clinical aspects previously described in FXS. The finding of decreased movement in Fmr1-KO mice is novel, and suggests a dissociation between baseline and novelty-evoked activity for Fmr1-KO mice.

The interactions of exogenous phytase with whole grain feeding and effects of barley as the whole grain component in broiler diets based on wheat, sorghum and wheat-sorghum blends

The objectives of this experiment were two-fold; the first was to evaluate exogenous phytase in either conventional or whole grain diets as a 2×2 factorial treatment array. Wheat-sorghum blended rations containing 12.5% ground or whole barley were offered without and with 1000 FTU/kg exogenous phytase. The second objective was to evaluate barley as the whole grain component in diets based on wheat, sorghum and equal wheat-sorghum blends as a 3×2 factorial treatment array. Rations based on wheat, sorghum and wheat-sorghum blends were offered as an intact pellet containing 12.5% ground barley or offered as a mix of 12.5% whole barley and a pelleted concentrate. Each of the dietary treatments was offered to 7 replicates (6 birds per cage) of male Ross 308 chicks from 7 to 28days post-hatch. Treatment effects on growth performance, gizzard and pancreas weights, gizzard pH, bone mineralisation, nutrient utilisation, digestibility coefficients of starch and protein (N) and starch:protein disappearance rate ratios in four small intestinal segments (proximal and distal jejunum, proximal and distal ileum), excreta dry matter and incidence of dilated proventriculi were determined. In the 2×2 analysis there was a significant (P<0.025) treatment interaction for FCR. Phytase addition to whole barley diets improved FCR by 3.20% (1.362 versus 1.407) but phytase compromised FCR by 3.11% (1.391 versus 1.349) in ground barley diets. Similarly, treatment interactions (P<0.002−<0.001) were also observed for energy utilisation (AME, ME:GE ratios, AMEn) where phytase generated positive responses in the context of whole grain feeding but not in conventional diets. In the 3×2 analysis, whole barley significantly increased relative gizzard weights by 22.5% (16.96 versus 20.77g/kg; P<0.001) and significantly reduced (P<0.05) the incidence of dilated proventriculi from 4.76% to zero. However, whole barley compromised growth performance. There were significant treatment interactions (P<0.001) for parameters of energy utilisation as whole barley significantly enhanced energy utilisation (AME, ME:GE ratios, AMEn) in birds offered sorghum-based diets but this was not the case with wheat or blended diets. Wheat-based diets generally supported better protein and starch digestibility coefficients with significant advantages being observed in some small intestinal segments in comparison to sorghum and blended diets. For example, wheat-based diets generated significantly higher protein digestibility in the ileum (P<0.001) than birds offered sorghum or blended diets. Likewise, wheat-based diets generated significantly higher starch digestibilities in the proximal jejunum and distal ileum (P<0.001) than birds offered sorghum or blended diets. Whole barley reduced water intakes by 9.72% (325 versus 360g/bird/day; P<0.01) and significantly increased excreta dry matter in wheat-based diets from 22.1 to 25.1% (P<0.001) but there was a decrease from 26.08 to 24.50% (P<0.05) in sorghum-based diets. Therefore, it may be concluded that phytase is more effective in whole grain diets than conventional diets. Whole barley increased gizzard weights, reduced the incidence of dilated proventriculi and significantly improved energy utilisation in sorghum based diets.

Antidiabetes dari Fraksi Air Daun Karamunting (Rhodomyrtus tomentosa (Ait.) Hassk.) Terhadap Kadar Glukosa Darah Mencit Diabetes

Karamunting salah satu tumbuhan yang digunakan sebagai obat tradisional penyakit diabetes mellitus. Penelitian telah dilakukan terhadap uji efek antidiabetes fraksi air daun karamunting (Rhodomyrtus tomentosa (Ait.) Hassk.) pada mencit putih jantan diabetes yang diinduksi dengan aloksan dosis 200 mg/kgBB secara intraperitonial. Fraksi air diberikan secara oral dengan dosis 10, 20 dan 40 ml/kgBB selama 15 hari. Parameter yang diukur adalah kadar glukosa darah, berat badan, volume urin, dan volume air minum. Hasil penelitian menunjukkan bahwa fraksi air daun Rhodomyrtus tomentosa (Ait.) Hassk oral dengan dosis 10, 20 dan 40 mg/kgBB mampu menurunkan kadar glukosa darah mencit diabetes yang diinduksi aloksan secara bermakna (P&lt;0,05), dapat memperbaiki berat badan, volume urin, dan konsumsi air minum mencit diabetes (P&lt;0,05).

Drinking frequency effects on the performance of cattle: a systematic review.

This study used a systematic literature review methodology to determine whether there is evidence that drinking frequency has effects on cattle performance, what performance responses to drinking frequency are documented and how performance responses vary according to environmental and animal factors. Electronic databases were searched for English language articles with original data on at least one performance attribute (e.g. water intake, feed intake, live weight) of cattle in response to voluntary drinking frequency or controlled access periods to water. Sixteen experiments on dairy cows and 12 experiments on beef cattle were retrieved from the literature. For beef cattle, all experiments reported reduced water and feed intake with access to water once every second and/or third day compared with once-daily access. Median reductions of 15% and 25% in water intake and 16% and 9% in feed intake were found across experiments respectively. Live weight responses of beef cattle to access to water were limited and yielded positive, negative and no effects. For dairy cows, most experiments reported reduced water intake, milk yield and milk fat content with access to water twice or once daily compared with controls (adlibitum or adlibitum except at the dairy). Median reductions of 13% and 12% in water intake, 2% and 1% in milk yield and 1% and 2% in milk fat content were found across experiments respectively. Water availability effects on feed intake and live weight were very limited for dairy cows and yielded positive, neutral and negative effects. Season, climate, experiment conditions, animal class and animal genotype were identified to potentially influence intake responses of cattle. The review highlights a number of important gaps in the literature where future work is required to better understand the optimum drinking frequency of cattle and implications of water availability on health, welfare and performance.

Effective Reduction in High Ethanol Drinking by Semisynthetic Tetracycline Derivatives.

New pharmacotherapies to treat alcohol use disorders (AUD) are needed. Given the complex nature of AUD, there likely exist multiple novel drug targets. We, and others, have shown that the tetracycline drugs, minocycline and doxycycline, reduced ethanol (EtOH) drinking in mice. To test the hypothesis that suppression of high EtOH consumption is a general property of tetracyclines, we screened several derivatives for antidrinking activity using the Drinking-In-the-Dark (DID) paradigm. Active drugs were studied further using the dose-response relationship. Adult female and male C57BL/6J mice were singly housed and the DID paradigm was performed using 20% EtOH over a 4-day period. Mice were administered a tetracycline or its vehicle 20hours prior to drinking. Water and EtOH consumption was measured daily. Body weight was measured at the start of drug injections and after the final day of the experiment. Blood was collected for EtOH content measurement immediately following the final bout of drinking. Seven tetracyclines were tested at a 50mg/kg dose. Only minocycline and tigecycline significantly reduced EtOH drinking, and doxycycline showed a strong effect size trend toward reduced drinking. Subsequent studies with these 3 drugs revealed a dose-dependent decrease in EtOH consumption for both female and male mice, with sex differences in efficacy. Minocycline and doxycycline reduced water intake at higher doses, although to a lesser degree than their effects on EtOH drinking. Tigecycline did not negatively affect water intake. The rank order of potency for reduction in EtOH consumption was minocycline>doxycycline>tigecycline, indicating efficacy was not strictly related to their partition coefficients or distribution constants. Due to its effectiveness in reducing high EtOH consumption coupled without an effect on water intake, tigecycline was found to be the most promising lead tetracycline compound for further study toward the development of a new pharmacotherapy for the treatment of AUD.

EFFECT OF VITAMIN C, VITAMIN E OR BETAINE ADDITION ON ALLEVIATION OF HEAT STRESS IMPACTS ON GROWING RABBITS

This study was conducted to evaluate the effects of vitamin C (VC), vitamin E (VE) or betaine (BET) dietary supplementation on growth performance, nutrients digestibility and antioxidant status of growing male rabbits under heat stress conditions. A total of 48 weaned New Zealand male rabbits with 641±15.77 g average body weight and 5 weeks of age was randomly divided to four experimental groups (12 rabbits per group), each was fed a basal diet without any supplementation (control group) or supplemented with 500 mg VC (2 nd group), 200 mg VE (3 rd group) or 1000 mg BET (4 th group)/kg diet for 8 weeks. Throughout the experiment, the overall mean of temperature humidity index (THI) was 84.67± 0.35, reflecting a state of severe heat stress. Results of growth performance showed that rabbits receiving VE, VC or BET had significantly higher live body weight (LBW), daily body weight gain (DBWG), and reduced water intake and feed conversion rate (FCR) as compared to the non-supplemented group. In particular, BET supplemented growing rabbits showed significantly marked improvement of the digestibility of dry matter (DM), organic matter (OM), crude protein (CP) and nitrogen free extract (NFE) and nutritive values compared to the non-supplemented group. All tested additives evoked significant improvement of antioxidant status, lipid peroxidation, white blood cells (WBCs) and lymphocyte count. Conclusively, the results revealed that VE, VC and BET could be useful as an economic efficient and natural dietary additives protecting against the negative impacts of heat stress in growing rabbits to maintain performance and antioxidant status.

Temporary amygdala inhibition reduces stress effects in female mice

The current study investigated the effect of temporary inhibition of amygdala in response to metabolic changes caused by stress in female mice. Unilateral and bilateral amygdala cannulation was carried out, and after a week of recovery, 2% lidocaine hydrochloride was injected into the mice amygdalae five minutes before the induction of stress. A communication box was employed to induce stress for four consecutive days and plasma corticosterone, food and water intake, weight changes, and anorexia were measured as stress-induced metabolic changes. Results demonstrated that stress, increases stress, increased plasma corticosterone concentrations, weight, food, and water intake. Temporary inhibition of the amygdala slightly decreased plasma corticosterone concentrations, but did not fully reduce the effect of stress. The bilateral injection of lidocaine hydrochloride to the amygdala reduced the effect of stress and reduced water intake and weight. Unilateral injection of lidocaine hydrochloride into the left and right amygdala reduced food intake. In conclusion, the present study demonstrated that the left side and right side of amygdala nuclei play a different role in metabolic responses in stress.

Suppression of TRPV4 channels ameliorates anti-dipsogenic effects under hypoxia in the subfornical organ of rats.

The phenomenon of water intake reduction during the 1st day of hypobaric hypoxia has been known for a long time. However, the reason for the same is yet unknown. The transient receptor potential vanilloid (TRPV) channels, including TRPV1 and TRPV4, are located in the subfornical organ (SFO). These are calcium permeable cationic channels gated by various stimuli such as cell swelling, low pH, and high temperature, and participate in anti-dipsogenic effects when activated. We aimed to explore the drinking behavior of rats and the mechanism of TRPVs under hypoxia. Chemical TRPV4 inhibitors (HC-067047 and Gadolinium) or TRPV4 knockout, but not TRPV1 inhibitor SB-705498, could restore the water intake under hypoxia. Hypoxia-mediated direct activation of TRPV4 may be the reason of anti-dipsogenic effects because the serum sodium, pH, and intracranial temperature are unaltered. Interestingly, we found that hypoxia immediately increased the intracellular Ca2+ concentration ([Ca2+]i) in HEK293-TRPV4 cells and primary neurons from SFO region, but not in the HEK293-TRPV1 cells. Moreover, hypoxia-induced [Ca2+]i increase depended on the indispensable hemeoxygenase-2 (HO-2) and TRPV4. HO-2 and TRPV4 were also confirmed to form a complex in SFO neurons. These results demonstrated that SFO cells sense hypoxia and activate via the HO-2/TRPV4 multiple channels, which are associated with anti-dipsogenic effects.

Intermittent heat exposure and thirst in rats.

Adequate water intake, supporting both cardiovascular function and evaporative cooling, is a critical factor in mitigating the effects of heat waves, which are expected to increase with global warming. However, the regulation of water intake during periods of intermittent heat exposure is not well understood. In this study, the effects of access to water or no access during intermittent heat exposure were assessed using male Sprague‐Dawley rats exposed to 37.5°C for 4 h/day. After 7 days of intermittent heat exposure, reductions in evaporative water loss were observed in all animals and reductions in water intake following heat exposure occurred as the days of heat exposure increased. Rats that were not allowed water during the 7 days of exposure had decreased rehydration levels, however, rats allowed access to water increased water intake during exposure and exhibited higher overall rehydration levels over the same time period. Peripheral administration of angiotensin II, mimicking activation of volemic thirst, or hypertonic saline solution, activating intracellular thirst, did not result in alteration of water intake in rats exposed to heat with access to water compared to control rats. In contrast, rats exposed to heat without access to water had reduced water intake after administration of hypertonic saline and increased water intake after administration of angiotensin II compared to control rats. These experiments demonstrate that thirst responses to intermittent heat exposure are altered by providing water during heat exposure and that intermittent heat exposure without access to water alters drinking responses to both intracellular and extracellular thirst challenges.

Maternal corticosterone exposure in the mouse programs sex-specific renal adaptations in the renin-angiotensin-aldosterone system in 6-month offspring.

Short‐term maternal corticosterone (Cort) administration at mid‐gestation in the mouse reduces nephron number in both sexes while programming renal and cardiovascular dysfunction in 12‐month male but not female offspring. The renal renin–angiotensin–aldosterone system (RAAS), functions in a sexually dimorphic manner to regulate both renal and cardiovascular physiology. This study aimed to identify if there are sex‐specific differences in basal levels of the intrarenal RAAS and to determine the impact of maternal Cort exposure on the RAAS in male and female offspring at 6 months of age. While intrarenal renin concentrations were higher in untreated females compared to untreated males, renal angiotensin II concentrations were higher in males than females. Furthermore, basal plasma aldosterone concentrations were greater in females than males. Cort exposed male but not female offspring had reduced water intake and urine excretion. Cort exposure increased renal renin concentrations and elevated mRNA expression of Ren1, Ace2, and Mas1 in male but not female offspring. In addition, male Cort exposed offspring had increased expression of the aldosterone receptor, Nr3c2 and renal sodium transporters. In contrast, Cort exposure increased Agtr1a mRNA levels in female offspring only. This study demonstrates that maternal Cort exposure alters key regulators of renal function in a sex‐specific manner at 6 months of life. These finding likely contribute to the disease outcomes in male but not female offspring in later life and highlights the importance of renal factors other than nephron number in the programming of renal and cardiovascular disease.

A Novel Hypothalamic Action of Adropin: Regulation of Fluid Homeostasis

Adropin, a recently described endogenous peptide encoded by the Energy Homeostasis Associated (Enho) gene, has been reported to be abundantly produced in the liver, smooth muscle and brain. While clinical and transgenic studies have identified adropin as a potent peripheral regulator of energy homeostasis, little is known about its action within the CNS. Therefore, the purpose of our study was to investigate a potential hypothalamic site of action to regulate ingestive behaviors. Male Sprague‐Dawley rats (200–250g) bearing an indwelling cannula in the right lateral ventricle were placed in metabolic cages with free access to lab chow and water (lights out 1800–0600h). During a two‐day habituation period, body weight and ad libitum water and food intakes were recorded. On the day of the experiment, rats were given a 2μl i.c.v. injection of vehicle or vehicle containing 0.3nmol, 1nmol, or 3nmol adropin at 1730h. Cumulative water and food intake was recorded in 30‐minute intervals until 1930h and again the next day at 0800h. While exogenous adropin had only a modest effect on food intake, we observed a profound inhibitory action on anticipatory water intake. Furthermore, after overnight water deprivation male rats administered 3nmol adropin i.c.v. exhibited significantly reduced water intake compared to vehicle treated controls. Importantly, using a deductive ligand receptor matching strategy (AJP 303:R941, 2012) we have identified a putative receptor for adropin. To demonstrate a functional relationship between our candidate receptor and adropin, rats were pretreated with i.c.v. injections of siRNA targeted against either eGFP as a control or our candidate receptor, followed by overnight dehydration and treatment with 3nmol adropin i.c.v. Cumulative water intake was recorded over the next four hours. Compromise of the endogenous candidate receptor significantly abrogated the adropin‐induced inhibition in dehydration‐stimulated water intake. Not only are these studies the first to demonstrate physiologic relevance of adropin as a central regulator of fluid homeostasis, but they provide compelling evidence that the adropin receptor is a formerly orphaned, G protein‐coupled receptor.Support or Funding InformationNIH RO1 HL121456

Development and characterization of microemulsions containing hyaluronic acid

Tween80 and Span20 were used as surfactant mixture for developing non-ionic microemulsions (MEs) containing hyaluronic acid 22kDa (HA). The effect of Tween80:Span20 ratio (T:S ratio) on microemulsion (ME) water intake and stability was studied. Moreover, the effect of HA on the consumed surfactant amount which is for stabilizing the MEs, for reducing water intake was investigated. Two W/O MEs containing HA were optimized. The first ME was composed of 2% HA, 13.8% Tween:80:Span20 (2:3), 4.2% water and 79.9% isopropylpalmitate (IPP). The second was composed of 2% HA, 16% Span20, 9.6% water:dimethyl sulfoxide (W:DMSO) (6:3.6) and 72.4% medium chain triglycerides (MCTG). The droplet sizes of MEs were determined using dynamic light scattering (DLS). The multilayer membrane system (MLMS) was used for testing the release of HA from both MEs and the released amount of HA was quantified using capillary zone electrophoresis (CZE). Furthermore, three phase diagrams and relevant rheological characteristics were generated. The droplet size of the ME without HA decreased and increased with increasing the temperature. Furthermore, the droplet size of the IPP-ME and MCTG-ME without HA and of the MCTG-ME with HA decreased with increasing temperature. In contrast to this results, the droplet size of the IPP-ME with HA increased with increased temperature. This ME belongs to the Newtonian fluids.Compared to the first ME, the second ME shows droplet sizes at 25°C of 6.5nm without and 37nm with HA. The droplet size in the second ME decreased proportionally with an increase of the temperature with and without HA.The release of HA was faster from the IPP ME compared to the MCTG-ME. The two developed MEs were stable, isotropic and their properties comply with ME properties concerning the droplet size and viscosity.

Early exposure to and subsequent beef cattle performance with saline water

Two experiments were conducted to evaluate the impact of early life exposure to high salt water on later cattle performance with saline water. In Exp. 1, 24 cow/calf pairs were randomly assigned to one of two treatments: exposure to high salt water [HSW; 7478mg/kg of total dissolved solids (TDS)] or to low salt water (LSW; 512mg/kg TDS) when calves were 2 to 6 mo. old. Then all calves drank low salt water for 6 mo, and subsequently high salt water for 30 d. During the last period HSW tended to eat 10% less DM (DMI; P=0.07) and drank 22% less water than LSW (WI; P<0.01). Total tract DM digestibility (TTDMD; P=0.92), blood parameters (hemoglobin and hematocrit; P>0.13), plasma glucose (P=0.18), serum minerals (P>0.08) and weight gain (ADG; P=0.85) were not affected by treatment. In Exp. 2, 24 pregnant heifers in the last month of gestation were randomly assigned to either HSW (10827mg/kg TDS) or LSW. The exposure period ended when calves were 3 month old. Then all calves drank low salt water for 95 d, and subsequently high salt water for 30 d. During the last period no significant differences between treatments were observed for DMI (P=0.43), WI (P=0.61), TTDMD (P=0.92), blood parameters (P>0.42), plasma rennin activity (PRA; P=0.35), and ADG (P=0.16). However, HSW drank less (P<0.01) high salt water than LSW during the first two hours of drinking water restoration after a water deprivation period of 20h. Overall, in the conditions of our study we did not find evidence that early exposure to saline water induces tolerance and improves later performance of beef cattle with salty water. However, reduced water intake (Exp. 1) and increased thirst threshold (Exp. 2) of animals early exposed to saline water need further consideration.

English

Improved fallows of Sesbania sesban (Sesbania) have been known to improve soil physical and chemical properties and increase crop yield compared to traditional fallows. However, the effects of soil tillage practices after improved fallows on soil properties, weeds, labour and subsequent maize crop has not been assessed in Southern Africa. This study aimed to evaluate how tillage practices affect yield of maize and affect soil properties after two years of fallow and subsequent cropping phase. In this study, done at sites in eastern Zambia, maize yield from a two-year planted Sesbania, natural fallow, continuously fertilized and unfertilized maize were compared under conventional, flat till and zero tillage practices. A split plot experiment, with improved fallow systems in the main plot and the tillage practice in the subplot, was established at the sites. The results showed that the increases in grain yield under conventional tillage over zero tillage practice were 17.8 and 28.2% during 2000/2001 and 2001/2002 seasons, respectively, at Msekera. At Chadiza, the increases in grain yield under conventional tillage over zero tillage were 66.3 and 327.4% during 2000/2001 and 2001/2002 seasons, respectively. Greater maize yields were achieved under Sesbania planted fallows compared to the natural fallow and maize monoculture without fertilizer. Overall, zero tillage practice resulted in lower maize grain yield, higher bulk density, reduced water intake, higher weed infestation and high labour demand during weeding compared to conventional tillage. Key words: Conventional tillage, flat till, grain yield, water intake, weeds, zero tillage.

Experimental infection with cytopathic bovine viral diarrhea virus in mice induces megakaryopoiesis in the spleen and bone marrow.

Here, we infected mice with cytopathic bovine viral diarrhea virus 1 (cp BVDV1) by oral inoculation and investigated the effects of infection by histopathological, immunohistochemical (IHC), hematological methods. Twelve mice were infected, and samples were obtained at day 2, 5, and 9 postinfection (pi). Most of the infected mice exhibited clinical signs of illness such as reduced movement, crouching, loose feces, loss of appetite, and reduced water intake. Blood samples from six mice were positive for BVDV based on reverse transcription polymerase chain reaction (RT-PCR). Blood analysis also revealed thrombocytopenia and lymphopenia. Viral antigens were detected in the spleen (12/12), bone marrow (12/12), and/or mesenteric lymph nodes (4/12) of all infected mice by IHC analysis. The spleens showed significant histopathological changes including (i) substantially increased numbers of megakaryocytes, (ii) lymphocyte depletion, and (iii) hemorrhages. The bone marrow also had an increased number of megakaryocytes, although this increase was not as strong as it was in the spleen. Severe lymphoid depletion was observed in the mesenteric lymph nodes. Viral infections were present in the lymphocytes but not detected in megakaryocytes of the spleen, bone marrow, or mesenteric lymph nodes. These results suggest that the increased numbers of megakaryocytes may be a direct result of BVDV infection. BVDV infection in mice following oral inoculation of cp BVDV1 leads to megakaryopoiesis in the spleen and bone marrow to replenish the platelets.