Impact of Heat Stress on Electrocardiographic Changes in New Zealand White Rabbits

A study was conducted on twelve clinically normal and healthy New Zealand White rabbits of both sexes, weighing between 2-3 kg, and aged between 1-3 years to observe the normal electrocardiogram and its changes during heat stress. The normal electrocardiogram and changes during heat stress were evaluated for the three bipolar standard limb leads (I, II and III) and three unipolar augmented limb leads (aVR, aVL and aVF). ECG recordings were made in sternal recumbency using a multi channel electrocardiograph . The normal heart rate with a mean of 204±7 beats/min was recorded. The mean amplitude observed was 0.05±0.002 mV for P wave; 0.19±0.008 mV for QRS; 0.14±0.007 mV for T wave. The mean duration observed was 0.03±0.002 sec for P wave; 0.06±0.002 sec for PR interval; 0.05±0.003 sec for QRS complex; 0.13±0.004 sec for QT interval; 0.07±0.002 sec for T wave. During heat stress tachycardia was observed with progressive rise in temperature along with ventricular fibrillation, ventricular extra-systole and atrial fibrillation. At 43°C, ventricular fibrillation was observed in Lead II, III, aVL and aVF. At 45°C, ventricular extra-systole was recorded in Lead III, aVL and aVF. At 45°C (30 mins more exposure), ventricular extra-systole in Lead I and ventricular fibrillation in Lead III was observed. At 47°C, ventricular fibrillation was seen in Lead II, III, aVR, aVL and aVF. At 47°C (30 mins more exposure), atrial fibrillation in all the leads were observed. The mean cardiac axis recorded was 90°±0.065 without significant alterations throughout the study

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Not AvailableThis study aimed to evaluate the impact of evaporative cooling during late gestation on physiological responses, blood gas and acid base balance and subse quent milk production of Murrah buffaloes. To investigate this study sixteen healthy pregnant dry Murrah buffaloes (second to fourth parity) at sixty days prepartum were selected in the months of May to June and divided into two groups of eight animals each. One group of buffaloes (Cooled/CL) was managed under fan and mist cooling system during dry period. Group second buffaloes (Noncooled/NCL) remained as control without provision of cooling during dry period. The physiological responses viz. Rectal temperature (RT), Respiratory rate (RR) and Pulse rate were significantly (P < 0.05) lower in group 2, with the provision of cooling. Skin surface temperature at thorax was significantly lower in cooled group relative to noncooled group. Blood pH and pO2 were significantly (P < 0.05) higher in heat stressed group as compared to the cooled group. pCO2, TCO2, HCO3, SBC, base excess in extracellular fluid (BEecf), base excess in blood (BEb), PCV and Hb were significantly (P < 0.05) higher in cooled group as compared to noncooled group. DMI was significantly (P < 0.05) higher in cooled relative to noncooled animals. Milk yield, FCM, fat yield, lactose yield and total solid yield was significantly higher (P < 0.05) in cooled group of Murrah buffaloes.Not Availabl

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Not AvailableThe objective of the study was to observe the effect of evaporative cooling during late gestation on immunity around the transition period and the probable outcome on reproductive disorders in Murrah buffaloes. Sixteen pregnant dry Murrah buffaloes at 60 days prepartum were selected and divided into two groups of eight animals each. Group 1 buffaloes remained without the provision of cooling, whereas the second group of buf faloes was managed under fans and mist cooling during the dry period. After parturition, all the animals were managed under evaporative cooling. Dry matter intake was signifi- cantly (P < 0.05) higher in cooled relative to noncooled animals at 15, 0, and þ20 days of parturition. Cortisol and prolactin levels were significantly (P < 0.05) higher in noncooled relative to cooled animals at 15 and 0 days of parturition. However, prolactin was significantly (P < 0.05) higher in cooled animals at þ20 days. Messenger RNA expression of prolactin receptor gene (PRL-R) was upregulated and suppressor of cytokine signaling gene 1 (SOCS-1) was downregulated in cooled animals at 20, 0, and þ20 days of parturition. Tumor necrosis factor a and interleukin 4 levels remained significantly (P < 0.05) higher in cooled animals at 20, 0, and þ20 days of parturition. Interleukin 6 was significantly (P < 0.05) lower in cooled animals at 20 and 0 days. Interferon g levels were significantly higher at 20 and þ20 days of parturition in cooled relative to noncooled animals. The reproductive disorders such as retention of placenta, metritis, and endometritis occurred at the rate of 37.25%, 25%, and 12.25% in the noncooled group, whereas only retention of placenta was observed in the cooled (12.5%) group.Not Availabl

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Not Availablestock adversely vis-à-vis production and reproduction. This has prompted more focus in addressing the unfavorable effects of thermal stress in livestock system. Presuming that the trace element zinc is in dispensible for cellular antioxidant system and immune function, the present study was designed to investigate the effect of zinc treatment on heat stress alleviation and immune modulation in peripheral blood mononuclear cells (PBMC) of indigenous and crossbred transition cows. Twelve cows, six each of Sahiwal and Karan Fries (KF) in their second parity with confirmed pregnancy were selected for the experiment. The blood samples were collected at 21, 0 and þ21 days in relation to expected date of calving. The experiment was carried out in vitro after isolating PBMC from whole blood. The 48 h cultured PBMC were subjected to assorted levels of exposures viz. 37 °C, 42 °C to impose heat stress and 42 °Cþzinc to alleviate heat stress and modulate immunity. The PBMC viability was 86%, 69% and 78%, respectively. The mRNA expression of heat shock proteins (HSP 40, 70 and 90α) and Interleukin-10 (IL- 10) production varied between the two breeds vis-à-vis days and levels of exposure. The mRNA ex pression of HSP40 and HSP70 was significantly (Po0.05) higher in Karan Fries than the Sahiwal cows. Both the breeds showed maximum expression of HSP on the day of parturition, more so in KF than Sahiwal. There was a significant (Po0.05) difference in the HSP mRNA expression at different levels of exposure. Zinc treatment to heat stressed PBMC caused a significant (Po0.05) down regulation of HSP. For immune status, anti-inflammatory cytokine, IL-10 in the culture supernatant was accessed. The IL-10 was significantly (Po0.05) higher in Karan Fries (168.18714.09 pg/ml) than the Sahiwal cows (147.24711.82 pg/ml). The IL-10 concentration was highest on the day of calving. Zinc treatment reduced the IL-10 concentration. From the study, it could be concluded that the zinc supplementation in heat stressed PBMC can ameliorate thermal stress and modulate immune response which can act as a model for reducing heat stress during the periparturient period in tropical livestock. & 2016 PNot Availabl

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Not AvailableThe current study was undertaken to evaluate the invitro effect of zinc treatment on the Superoxide Dismutase (SOD) and Catalase status in the heat stressed Peripheral Blood Mononuclear Cells (PBMC) of periparturient indigenous and crossbred cows. Twelve pregnant cows, six each from Sahiwal and Karan Fries in their second parity were selected for the experiment. Blood samples were collected at -21, 0 and +21 days with respect to calving from each animal. The 48 hour long cultured PBMC were exposed to three levels of treatment viz., 37oC, 42oC to induce thermal stress and 42oC+Zinc to minimize the effect of high temperature. SOD and Catalase showed a significant (P<0.05) difference between the two breeds, more concentration being found in Karan Fries. While comparing the days, the concentration of both SOD and Catalase was found to be more on the day of calving though non-significantly in case of SOD but the difference was significant (P<0.05) vis-à-vis Catalase. Zinc treatment caused a decreased production of both SOD and Catalase which were otherwise increased due to thermal stress. The antioxidant concentration was highest due to thermal stress in Karan Fries on the day of calving. The oxidative stress supervenes during peripartum and heat stress which could be alleviated by zinc treatment.Not Availabl