Biomedical subjects

D Shinder

Publications and source records attributed to D Shinder.

13 recordsLinked to original sources

PubMed2004

Hormonal changes associated with ageing and induced moulting of domestic hens.

1. The effect of age on ovarian function was studied in 245-, 350-, 500-, 700- and 800-d-old Lohmann hens. The effect of three different methods for moult induction on ovarian function and corticosterone concentration was studied in 500-d-old hens. 2. No significant reductions in ovarian weight or in number of follicles before the age of 700 d were found. The ability to produce progesterone and oestradiol-17beta was unchanged up to the age of 700 d and the circadian secretion of these two steroids was identical in young (225 d) and old hens (600 d). 3. The effects of induced moulting by feed withdrawal (FW) and a high Zn (HZn) diet on body weight and ovarian function were very similar; those of a moderate Zn with low Ca (MZn/LCa) diet were smaller. 4. The first significant effect of moulting was a decrease in oestradiol-17beta plasma concentration (d 2). Plasma progesterone decreased more gradually than oestradiol-17beta, and reached a nadir on d 6 in FW- and HZn-treated hens and on d 9 in MZn/LCa-treated ones. 5. Hens treated with either FW or the MZn/LCa, but not those with the HZn diet, showed a very sharp rise in corticosterone concentration on d 2 of treatment. Thus the MZn/LCa diet was less efficient than the other treatments in induction of ovarian involution, but had a similar effect on stress induction, as indicated by increases in plasma corticosterone.

Aging↗

PubMed2004

Thermal manipulations during broiler chick embryogenesis: effects of timing and temperature.

This study aimed at elucidating the effects of thermal manipulation (TM) during different periods of embryogenesis on hatchability, body weight, and thermoregulation of Ross chicks at hatch, and on the chick's ability to cope with thermal challenge (TC) at 3 d of age. Control embryos were incubated at 37.8 degrees C and 56% RH, whereas the TM embryos were treated for 3 h at 39.5 (1) or 41.0 degrees C (2) and 65% RH, during early embryogenesis (EE), E8 to E10, and late embryogenesis (LE) at E16 to E18. At hatch, after feather drying, BW and body temperature (Tb) were measured, blood was drawn from the jugular vein to measure plasma concentrations of thyroxine (T4), triiodothyronine (T3), and corticosterone. These parameters were also measured in 3-d-old chicks during exposure to TC at 41 degrees C for 6 h. Hatchability was significantly higher in the LE1-treated group than in the other treatments. EE1- and LE1-treated embryos exhibited significantly lower Tb at hatch than the LE2 chicks. Significant hyperthermia was noted in the control chicks during 6 h of TC; it coincided with a higher plasma T3 concentration (P = 0.074). During TC, the LE1-treated chicks exhibited the lowest T3 to T4 ratio and a significantly reduced plasma corticosterone concentration. It can be concluded that TM at 39.5 degrees C for 3 h during E16 to E18 of incubation improved chick's thermotolerance acquisition and reduced the corticosterone level of chicks exposed to TC at the age of 3 d.

Adaptation, Physiological↗

PubMed2004

Ventilation, sensible heat loss, broiler energy, and water balance under harsh environmental conditions.

Air velocity (AV) is one of the main environmental factors involved in thermoregulation, especially at high ambient temperatures. To elucidate the effect of AV on performance and thermoregulation of 4- to 7-wk-old broiler chickens, an experiment was conducted using 4 different AV (0.8, 1.5, 2.0, and 3.0 m/s) at constant ambient temperatature (35 +/- 1.0 degrees C) and RH (60 +/- 2.5%). BW, feed intake, and fecal and urinary excretions were monitored in individuals and were used to calculate the amount of energy expended for maintenance. Infrared thermal imaging radiometry was used to measure surface temperatures for the calculation of heat loss by radiation and convection. Brachial vein blood was collected for plasma osmolality and arginine vasotocin analysis. Broilers performed optimally at an AV of 2.0 m/s. Energy expenditure for maintenance was significantly higher under these conditions, suggesting the ability to direct a sufficient amount of energy to control body temperature, while maintaining relatively high growth rates. Convective heat loss increased significantly with increasing AV, whereas radiative heat loss was not affected. Sensible heat loss, expressed as a percentage of energy expenditure for maintenance, was significantly higher at 2.0 m/s compared with 0.8 m/s but significantly lower than that of 3.0 m/s. The high level of heat loss observed at 3.0 m/s probably affected body water balance, as supported by significantly higher plasma osmolality, arginine vasotocin concentration, and the hyperthermic status of these birds. It can be concluded that AV of 2.0 m/s enables broilers to maintain proper performance together with efficient thermoregulation and water balance under harsh environmental conditions.

Air Movements↗

PubMed2003

Alternative procedures for molt induction: practical aspects.

Shortening daylight (to 10.5 to 11 h/d) slightly reduced the rest period (the interval between last egg and first clutch), whereas feeding a low-protein diet during the 22-d period following 8 d of feed withdrawal (FW) (recovery period) markedly extended it. Feed withdrawal accompanied by a short-daylight regime and a long recovery period led to the best postmolt production. However, production per hen housed during the whole experimental period was only slightly increased. Thus, a long rest period may mask the positive effects of short daylight and recovery diet. At least 140 to 170 d were needed to enable the molted hens to compensate for the loss of eggs during the rest period. Therefore, under certain economic conditions, rearing of nonmolting hens for 640 to 700 d should be an economic consideration. Ten days of feeding of a diet containing 0.06% nicarbazin (NICR) arrested egg production and caused a 22-d rest period but not a typical molt. Few variables of production or shell quality were improved by NICR but to a lesser extent than by FW or Zn feeding. Five days of feeding on a high-Zn diet (20 g Zn/kg; HZn) improved postmolt performances similarly to FW. Ten days of feeding on a modest-Zn (2.8 g Zn/kg), low-Ca, and low-P diet (Zn-CaP) affected postmolt performances inconsistently. In one out of two trials (trial 2), the effects of Zn-CaP were similar to those of FW or HZn; in the other (trial 3), the effects were less pronounced, more time was required for egg arrest, and more eggs were laid occasionally during the rest period. In trial 2, only the Zn-CaP diet was accompanied by short daylight. In both trials, feed intake during the induction period was only slightly reduced. Zn feeding increased the yolk Zn content slightly in eggs laid during the induction period and at the onset of production. In trial 2, only Zn-CaP markedly increased yolk Zn of eggs laid during the first 5 d of production.

Animal Feed↗

PubMed2003

Erythropoiesis regulation during the development of ascites syndrome in broiler chickens: a possible role of corticosterone.

The ascites syndrome in broiler chickens is attributed to metabolic burdening, which results from intensive genetic selection for rapid growth coupled with exposure to extreme environmental conditions, such as low ambient temperature. These conditions impose on the broilers difficulties in fulfilling tissue demands for oxygen, and the birds exhibit a decrease in blood oxygen saturation and high hematocrit values. It is unknown whether the increase in hematocrit results from alteration in erythropoiesis or from fluid exudation out of the blood system to the abdominal cavity. The present study was conducted to examine the association between abnormal stress response and erythropoiesis process in ascitic broilers. Ascitic chickens revealed a uniquely continuous stress response: expressing an increase (P < or = 0.05) in plasma corticosterone concentration 2 to 3 wk before death. At 5 wk of age, ascitic broilers exhibited an increase (P < 0.05) in hematocrit, blood cell count, and packed cells and blood volumes, with no significant change in plasma volume. These results confirm an accelerated erythropoiesis process in ascitic birds. Increased blood cell production in ascitic birds was matched by an increase (P < 0.05) in the proportion of immature red blood cells (23%) in comparison with broilers that remained healthy (7%), and by decreased (P < 0.05) hemoglobin content relative to red blood cells. We conclude that continually increased corticosterone concentrations, as an inducer of erythropoiesis proliferation and differentiation arrest, in ascitic chickens, resulted in increased production of red blood cells (partially immature) with decreased hemoglobin content; this decrease in hemoglobin might have contributed to enhanced development of hypoxemia and to aggravation of the syndrome.

Animals↗

PubMed2001

Air velocity alters broiler performance under harsh environmental conditions.

The effect of air velocity (AV) on weight gain, feed intake, and feed efficiency was studied in male broiler chickens exposed to a constant 35 C, 60% RH, and continuous illumination from 4 through 7 wk of age. In two separate trials, AV of 0.5, 1.5, 2.0, and 3.0 m/s (Trial 1) and 1.0, 1.5, 2.0, and 2.5 m/s (Trial 2) were used. The fifth week was used for acclimation to the targeted environmental conditions. Weight gain was significantly higher in broilers exposed to AV of 1.5 and 2.0 m/s in both trials, which coincided with significantly higher feed intake and feed efficiency. Exposure to the low AV (0.5 and 1.0 m/s) resulted in weight gain, feed intake, and feed efficiency that were less than those of broilers exposed to high AV (2.5 and 3.0 m/s). In all treatments, broilers developed hyperthermia, but there were no significant differences in body temperature (Tb) among the birds. It can be concluded that AV has a significant effect on broiler performance; the optimal AV was found to be 1.5 to 2.0 m/s.

Air Movements↗

PubMed2001

Association between weight gain, blood parameters, and thyroid hormones and the development of ascites syndrome in broiler chickens.

The present study examined the association between thyroid hormones and the development of ascites on one hand and the ability to predict ascites from growth rate and hematocrit on the other hand. Ascites syndrome was induced in broiler chickens in two trials by exposing the chicks to low ambient temperature (Ta) and by supplying a pellet form of diet. Weight gain, hematocrit, hemoglobin, and plasma thyroxin (T4) and triiodothyronine (T3) concentrations were measured weekly for each bird, and comparisons were made between birds that eventually died from ascites and those that did not. Mortality from ascites amounted to 24.3 and 24.2% in Trials 1 and 2, respectively. Weight gain did not differ between ascitic and healthy chickens up to approximately 2 wk before death but was significantly lower in the ascitic broilers 1 to 2 wk before death. Hematocrit was significantly higher in broilers with ascites with the exception of ascitic broilers that died at the age of 7 wk (Trial 1). In ascitic broilers, T4 and T3 concentrations declined significantly during the week of death. The present findings raise the question of whether the association between low levels of thyroid hormones and the development of ascites is one of the physiological responses in the syndrome cascade, or whether the failure to maintain thyroid hormones concentration is one of the triggers of the syndrome initiation. This question requires further investigation. It can be concluded that a high rate of weight gain is not always a good predictor of ascites development. Hematocrit and thyroid hormones can provide a good indication but only during the last week of life, and not in all cases. None of these parameters, however, can predict the development of ascites at an early age.

Animals↗

PubMed2000

Stress down regulates milk yield in cows by plasmin induced beta-casein product that blocks K+ channels on the apical membranes.

Stress and stress related hormones such as glucocorticoids inhibit lactation in cows. In the present study we propose a novel mechanism connecting stress with plasminogen-plasmin system (PPS) (an enzymatic mechanism in milk, which leads to the breakdown of the major milk protein casein). We show that stress activates the PPS leading to an increase in plasmin activity, and that a distinct plasmin-induced beta-casein breakdown product (fraction 1-28) is a potent blocker of potassium channels in mammary epithelia apical membranes. The reduction in milk production due to dehydration stress or glucocorticoid (dexamethsone) was correlated with the activities of plasmin and channel blocking activity in the milk of the tested cows. The notion that the axis Stress-PPS-beta-casein fraction 1-28 is responsible for the reduction in milk yield is supported by the results of experiments showing that injecting solution composed of casein digest enriched with beta-casein fraction 1-28 to the udder lumen leads to a transient reduction in milk production. Furthermore, injecting a pure beta-casein fraction 1-28 to the udder lumen of goat's lead also to a transient reduction in milk production with kinetics that was similar to the kinetics observed in cows.

Animals↗

PubMed2000

Lack of response of laying hens to relative humidity at high ambient temperature.

1. The effects of relative humidity (rh=40% to 70%) at high ambient temperature (Ta) on the performance of laying hens at different ages (8 to 10 months, Trial 1; and 16 to 18 months, Trial 2) was evaluated. Laying hens were exposed to 25 degrees C (control) for 3 weeks and thereafter acclimated for 1 week to 35 degrees C and 4 different rh. 2. Body weight declined significantly in young and older hens exposed to 60% or 70% and 70% rh, respectively: Food intake declined with increasing Ta, except in the case of older hens exposed to 60% rh, for which it remained relatively constant. Water consumption, however, increased with increasing Ta but the increase was significant in young hens exposed to 70% rh only. 3. Egg production was not affected by the changes in Ta. However, a decrease in egg production was observed in older hens exposed to 60% rh. 4. Egg weight (EW), shell weight (SW) and shell thickness (ST) were significantly reduced by exposure to elevated Ta, whereas % breakage significantly increased. In young hens, a response to rh was exhibited in ST which was significantly higher in hens exposed to the low rh (40% to 45%) than in those exposed to the highest rh (70% to 75%). 5. It can be concluded that Ta is the main environmental factor affecting young and older laying hens while the effect of rh is minor.

Age Factors↗

PubMed1999

Stunting syndrome in broilers: effect of electrolytes in drinking water on performance and intestinal glucose transport.

Posthatched naive or inoculated male broiler chicks were kept in separate rooms. An inoculum was prepared from intestines of stunting-syndrome affected broiler chicks. Tap water was supplied from 2 L cups, 1 cup per pen. In the Ist experiment, the naive chicks were provided with tap water only and the inoculated ones had free access to tap water or to an electrolyte solution. In the 2nd experiment, the naive and inoculated birds had free access to water in addition to an electrolyte solution. Supplementation was provided up to 3 weeks of age; thereafter all chicks had access to tap water only. Water or electrolyte consumption and body weight (BW) were determined. Total water intake of inoculated chicks was higher than that of naive counterparts (P<0.001). Electrolyte supplementation increased drinking (P<0.001) in inoculated birds more than in naive ones. At 1 week old the weight of the inoculated birds was about 64% of the weight of naive ones; at the age of 4 and 6 weeks it was about 74% and 86% respectively. Compensatory growth was most apparent in the inoculated chicks provided with electrolyte solution. At the age of 6 weeks, the latter exceeded the BW of the exclusively water supplied counterparts by 327 g. Electrolyte supplementation up to the age of 3 weeks had no effect on the naive counterparts. Osmolality was reduced slightly, but very significantly by inoculation; electrolyte supply had no effect on this variable. Sodium concentration in the plasma was higher in the inoculated birds. Plasma albumin was markedly reduced by inoculation on weeks 1 and 2. Whereas the inoculated chicks supplied with electrolytes resumed the level plasma albumin level of the naive chicks on week 3, an over-compensation occurred in the inoculated-water-supplied (IW) group, and they surpassed the naive chicks significantly. Blood hematocrit increased significantly with age; inoculation, age and/or electrolyte supplementation had no effect on this variable. Sodium-dependent glucose transport rates were enhanced in vesicles obtained from inoculated chicks as compared to naive ones. While electrolyte supplementation had no effect on glucose active transport in naive chicks, electrolyte supplementation decreased rates of glucose active transport in inoculated ones. These data demonstrate that electrolyte supplementation during the early age may be used to enhance the tolerance of broiler chicks to stunting-syndrome by improving food and water consumption, and subsequently growth rate during and after cessation of electrolyte supply.

Animals↗

PubMed1998

Metabolic and productive responses of dairy cows to increased ion supplementation at early lactation in warm weather.

We found previously that the current recommendations for Na+, K+, and Cl- contents in the diet do not meet the needs of lactating cows. The response of cows receiving a ration with increased amounts of Na+, K+, and Cl- (E cows) were compared with those of cows consuming the same ration with a fixed concentration of these ions (C cows) between weeks 2 and 8 post partum (PP). Milk, protein, fat and lactose yields, and dry matter intake between weeks 2 and 4 PP were higher in E than in C cows. These differences did not occur between weeks 4 and 8 PP, mainly because of a higher incidence of PP complications in E cows. A greater increase in plasma insulin-like growth factor-1 concentration in E than in C animals during weeks 2 and 3 PP was consistent with the milk responses. A reduction in aldosterone concentration in E cows in weeks 2 and 3 PP was a consequence of their Na+ requirements being satisfied as a result of their enhanced Na+ intake. A subsequent elevation in aldosterone concentration in E animals was probably related to a moderate excess in K+ intake. This increase in aldosterone explains the urinary potassium loss that was detected at week 6 PP. The absence of differences between E and C cows in plasma renin activity was consistent with an absence of differences in urine volume and with the apparent utilization of the enhanced ion intake for body functions.

Aldosterone↗

PubMed1997

Metabolism of water, sodium, potassium, and chlorine by high yielding dairy cows at the onset of lactation.

We studied the balance of Na+, K+, Cl-, and water in six high yielding (> 39 kg/d of milk) cows between wk 2 to 1 prepartum and at 2 and 7 wk postpartum during winter in Israel. Cows were fed complete diets; Na+ and Cl- contents exceeded dietary recommendations, and K+ content was equal to dietary recommendations. Milk yield was related positively and significantly to retention of Cl- and K+, indicating that ions that are the main constituents of sweat can limit the ability of cows to express full genetic potential. The highest ion retention was recorded for cows that had the highest dry matter intake and, hence, the highest ion intake. Retention of Cl- was highest for cows that were most efficient in retaining Cl- in the kidney. In hot climates, increasing the concentrations of ions in the diet of early lactation cows according to the actual dry matter intake could prevent or reduce the severity of ion deficiencies. Water turnover rate of the cows was dependent on dry matter intake, milk yield, and respiratory-cutaneous water loss. The milk-free water balance (water turnover rate minus water secreted in milk) could be very efficiently predicted for lactating and nonlactating cows by the following equation: milk-free water balance (kilograms per day) = digestible energy intake (megacalories per day) x 0.58 + respiratory-cutaneous loss (kilograms per day) x 0.97 (n = 18; R2 = 0.97). This formula provides a tool to assess the evaporative-cutaneous water loss from feed and water intake measurements to evaluate the severity of heat stress.

Animals↗

PubMedDate not supplied

AlphaMUPA mice: a transgenic model for increased life span.

AlphaMUPA is a line of transgenic mice that, compared with their wild type (WT) counterparts, spontaneously eat less (approximately 20%) and live longer (average approximately 20%), thus resembling dietary-restricted (DR) mice. Here, we show that body temperature was significantly reduced in alphaMUPA compared with WT throughout a wide range of ages. Plasma corticosterone was significantly higher in young alphaMUPA compared to young WT; however, it significantly declined in aged alphaMUPA, but not in aged WT. In addition, age-associated thymus involution occurred in alphaMUPA as it did in WT. Thus alphaMUPA mice appear to largely resemble, but also to somewhat differ from diet-restricted animals. We also report on four new transgenic lines that, like alphaMUPA, produced in the brain the mRNA that encodes the extracellular protease urokinase (uPA); however, transgenic uPA expression was most extensive and widespread in the alphaMUPA brain, where it also occurred in the hypothalamus. AlphaMUPA was also the only line that ate less, but also showed another characteristic, high frequency leg muscle tremor seen only at unstable body states. We hypothesize that transgenic uPA in the brain could have caused the alphaMUPA phenotypic alterations. Thus alphaMUPA offers a unique transgenic model of inherently reduced eating to investigate the homeostatic state of delayed aging at the systemic and single-cell levels.

Animals↗