S.V. Singh

Circadian changes in heat storage and heat loss through sweating and panting in Karan Fries cattle during different seasons

In order to find out the circadian variations in physiological responses, heat storage and heat loss, experiment was conducted on 12 female Karan Fries (KF) cattle selected from National Dairy Research Institute (NDRI) herd. Animals were further divided equally in two groups namely growing (8–12 months) and adults (18–24 months), and experiment was conducted during winter (December to January), spring (February to March) and summer (April to May) seasons. Physiological responses (respiration rate (RR), rectal temperature (RT), skin temperature (ST) and pulse rate (PR)), heat storage and heat loss through evaporation from skin (sweating) and pulmonary system (panting), dry bulb temperature (DBT) and wet bulb temperature (WBT), relative humidity, minimum and maximum temperatures, wind speed and temperature humidity index were calculated at 4-h intervals round the clock. Physiological responses (RR, RT, ST and PR) increased significantly (p < 0.01) during spring and summer season. RR and PR were positively correlated with DBT. The circadian rhythmic variations in core temperatures during summer season were 1.0°C and 1.4°C, respectively, for adult and growing KF cattle. Heat loss through skin and pulmonary system was maximum in adult (76.8% and 23.2%) during summer at 2 pm compared to growing (73.9% and 26.1%). Heat storage was found to be maximum in adult than growing during all seasons. Heat storage increases as the intensity of solar radiation increases, and also higher is the surface area higher is the heat storage. Therefore, the experiment was conducted to study the influence of heat stress during the different periods in crossbred cattle.

Expression of HSP70 genes in skin of zebu (Tharparkar) and crossbred (Karan Fries) cattle during different seasons under tropical climatic conditions

Skin is most important environmental interface providing a protective envelope to animals. Its always under the influence of both internal and external stressors. Heat shock proteins (HSP) are highly conserved stress proteins which play crucial roles in environmental stress tolerance and thermal adaptation. Present study was planned to observe the relative mRNA expression of inducible (HSP70.1 and HSP70.2) and constitutive (HSP70.8) HSP in skin of zebu (Tharparkar) and crossbred (Karan Fries) cattle during different seasons. Skin biopsies were collected from rump region of each animal, aseptically during winter, spring and summer season. Quantitative real time polymerase chain reaction was performed to examine the gene expression of constitutive (HSP70.8) and inducible (HSP70.1 and HSP70.2) HSP in skin of both the breeds during different seasons. Present study observed higher expression of both constitutive and inducible HSP genes in both the breeds during summer and winter than spring season, but magnitude of increase was higher during summer than winter. During summer season, expression pattern of HSPs in skin showed breed differences, where constitutive HSP expression was higher in Tharparkar than Karan Fries and that of inducible HSP was higher in Karan Fries than Tharparkar. Hence, present study suggested that HSP may be conveniently used as biomarkers for assessing protective response of skin against heat stress in zebu and crossbred cattle. Variation in expression between breeds is associated with their heat tolerance and thermal adaptability. In summary, skin of zebu cattle (Tharparkar) is more resistant to summer stress than crossbred (Karan Fries), providing greater protection against heat stress during summer season. Superior skin protective mechanism of zebu (Tharparkar) than crossbred (Karan-Fries) cattle against heat stress may contribute to superior adaptability of zebu cattle to tropical climatic conditions than crossbreed.

Seasonal variation in HSP70 expression and oxidative stress in skin of zebu (Tharparkar) and crossbred (Karan Fries) cattle under tropical climate

Abstract The study aimed to evaluate inducible HSP70 (HSP70.1 and HSP70.2) gene expression and oxidative stress status in skin of cattle during different seasons. Ten each of Tharparkar (zebu) and Karan Fries (crossbred) heifers were selected from NDRI herd, Karnal. Animals were maintained under standard managemental practices followed at the farm. Skin biopsies were aseptically collected from each animal during winter, spring, and summer. Real time PCR was performed to examine HSP70 expression. Reactive oxygen species (ROS) and antioxidant enzymes (SOD and CAT) were determined by ELISA. In both the breeds, significantly higher (p < 0.05) levels of HSP70 expression, ROS, caspases, and antioxidant enzymes were observed during summer followed by winter and spring. Breeds showed no significant difference during winter and spring. During summer, HSP70 expression, ROS, and antioxidant enzymes were higher (p < 0.05) in Karan Fries than Tharparkar, whereas caspases levels were higher in Tharparker than Karan Fries. The study concludes that levels of HSP70 expression, ROS, caspases, and antioxidant enzymes in skin of cattle were strongly affected by seasonal change in temperature. Differences exist in skin tissue thermotolerance of Tharparkar and Karan Fries cattle. This might be an efficient and centrally important mechanism for better adaptability of zebu cattle to heat stress.

Influence of astaxanthin supplementation on attainment of puberty and lipid peroxidation in Sahiwal and Karan Fries (Holstein × Tharparkar) heifers during summer season

ABSTRACT Present study was conducted on Sahiwal and Karan Fries (Holstein Friesian X Tharparkar) heifers to investigate the ameliorative effect of astaxanthin supplementation on oxidative stress and attainment of puberty during summer season. The heifers of both the breeds were equally divided into two groups i.e. control (fed as per ICAR, 2013) and treatment groups (additionally supplemented with astaxanthin @ 0.25 mg/kgBW/day/animal). THI was calculated at fortnightly interval during experimental period to assess the level of summer stress. The physiological responses were recorded and blood samples were collected at fortnightly interval from both the groups of both the breeds. The physiological response (RR, PR and RT) and plasma TBARS was (P ≤ 0.05) higher in control compared to treatment group of both the breeds. Plasma TAC and GH were significantly (P ≤ 0.05) higher, while, IGF-1 was numerically higher in treatment group of Sahiwal and Karan Fries heifers than control group. Astaxanthin supplementation alleviated the adverse effect of heat stress and improved the weight gain of heifers and hence helps in early attainment of puberty through conservation of energy, which could be otherwise used in dissipation of heat stress. The result was more pronounced in KF than Sahiwal heifers due to their exotic inheritance.

Estimation of metabolic heat production and methane emission in Sahiwal and Karan Fries heifers under different feeding regimes

Aim: The objective of this study was designed to estimate the metabolic heat production and methane emission in Sahiwal and Karan Fries (Holstein-Friesian X Tharparkar) heifers under two different feeding regimes, i.e., feeding regime-1 as per the National Research Council (NRC) (2001) and feeding regime-2 having 15% higher energy (supplementation of molasses) than NRC (2001). Materials and Methods: Six (n = 6) healthy heifers of Sahiwal and Karan Fries with 18-24 months of age were selected from Indian Council of Agricultural Research-National Dairy Research Institute, Karnal. An initial 15 days was maintained under feeding regime-1 and feeding regime-2 as adaptation period; actual experiment was conducted from 16th day onward for next 15 days. At the end of feeding regimes (on day 15th and 16th), expired air and volume were collected in Douglas bag for two consecutive days (morning [6:00 am] and evening [4:00 pm]). The fraction of methane and expired air volume were measured by methane analyzer and wet test meter, respectively. The oxygen consumption and carbon dioxide production were measured by iWorx LabScribe2. Results: The heat production (kcal/day) was significantly (p<0.05) higher in feeding regime-2 as compared to feeding regimen-1 in both breeds. The heat production per unit metabolic body weight was numerically higher in feeding regime-1 than feeding regime-2; however, the values were found statistically non-significant (p>0.05). The energy loss as methane (%) from total heat production was significantly (p<0.05) higher in feeding regime-1. The body weight (kg), metabolic body weight (W0.75), and basal metabolic rate (kcal/kg0.75) were significantly (p<0.05) higher in feeding regime-2 in both breeds. Conclusions: This study indicates that higher energy diet by supplementing molasses may reduce energy loss as methane and enhance the growth of Sahiwal and Karan Fries heifers.