Comparative assessment of climate resilient potential in four poultry genotypes reared in hot-humid tropical environment: a preliminary evaluation.

The general objective of this study is to comparatively assess the climate-resilient potential of four different poultry genotypes-Giriraja (n = 8), Country chicken (n = 8), Naked neck (n = 8), and Kadaknath (n = 8)-reared in a hot-humid tropical environment. Birds from all genotypes had ad libitum access to feed and water and were exposed to identical environmental temperatures in the experimental shed. Diurnal meteorological data were recorded inside and outside the shed daily. Blood biochemical, hormonal, and endocrine variables were monitored monthly until the birds reached 12 weeks of age. Significant variations (P < 0.01) were observed at different intervals in variables, including total protein, albumin, globulin, triglycerides, and cholesterol. Genotype-specific differences were noted in triglycerides (P < 0.01), albumin (P < 0.01), total protein (P < 0.05), and cholesterol (P < 0.05). Inter-genotype variations (P < 0.05) were also observed in serum cortisol, T3, and T4 levels. Distinct variations (P < 0.05) were also observed during specific intervals, particularly in cortisol and T3 levels. The study of hepatic mRNA expression of HSPs and HSF-1 revealed a significant breed difference (P < 0.05) in the expression pattern of HSP60, HSP70, HSP90, and HSP110, while no difference was observed between genotypes for HSP40 and HSF-1. The study highlights the Naked Neck breed as an exemplar of resilience, showcasing its distinctive ability to maintain homeostasis under heat stress compared to other genotypes. The genetic and physiological insights gained from this investigation offer prospective pathways for aligning sustainable poultry farming with environmental exigencies.

Comparing the responses of grain-fed feedlot cattle under moderate heat load and during subsequent recovery with those of feed-restricted thermoneutral counterparts: blood cells and inflammatory markers.

Given the climate projections for livestock rearing regions globally, understanding the inflammatory status of livestock under various heat loads will be informative to animal welfare and management. A survey of plasma inflammatory markers was conducted, and blood leucocyte counts followed to investigate the capacity of the ~ 500 kg grain fed Black Angus steer to respond to and recover from a moderate heat load challenge. Two sequential cohorts of 12 steers were housed in climate-controlled rooms (CCR) for 18 days. A thermally challenged (TC) group (n = 2 × 6) experienced five consecutive periods: PreChallenge, Challenge, and Recovery within the CCR, and 40 days in outdoor pens (PENS and Late PENS). PreChallenge (5 days) and Recovery (7 days) delivered thermoneutral conditions, whereas in Challenge the TC steers experienced a diurnal temperature range of 28-35 °C. A feed-restricted thermoneutral (FRTN) treatment (n = 2 × 6) was run concurrently to differentiate between responses to reduced feed intake alone and moderate heat stress. Blood neutrophil counts were particularly sensitive to moderate heat load with higher numbers during Challlenge and in PENs. The plasma concentrations of TNFα and IL-1ß were depressed in the TC group compared to the FRTN counterparts and remained so for 40 days after Challenge. Linear relationships of the concentrations of IL-1ß, IL-10, and haptoglobin with rumen temperature or dry matter intake detected in the FRTN group were altered or absent in the TC group. The findings suggest significant impacts of moderate heat load on the inflammatory status of feedlot cattle.

Do newborn lambs with black and white hair-coats in an equatorial semi-arid environment maintain homeothermy?

We assessed newborn lambs from two hair-coat sheep breeds, the black Santa Ines (n = 29) and white Dorper (n = 26), to determine how they behaviourally and physiologically respond to the prevailing thermal conditions in an equatorial semi-arid environment. Measurements of hair-coat surface temperature, rectal temperature and the lambs' exposure to sun were recorded across the first 24 h of life every hour, after the lambs had received colostrum. Lambs and ewes were kept in a lambing pen and could freely move between a shaded area or be exposed to sun. During the study period, the air temperature ranged between 20 ºC and 34 ºC. When exposed to sun, lambs and ewes could experience as much as 1200 W m-2 of solar irradiance. Santa Ines lambs exhibited higher (highest density interval at 95%, HDI) hair-coat surface temperatures than did Dorper lambs. Overall, both Santa Ines and Dorper lambs sustained homeothermy, with a mean rectal temperature ranging from 38.7 ºC to 39.1 ºC between night and daytime phase, and a mean amplitude of ~ 0.8 ºC. Nevertheless, from 10:00 to 15:00, some lambs were found to be moderately hyperthermic. Five Santa Ines and three Dorper lambs had rectal temperatures above 40 ºC, and one Santa Ines lamb, while exposed to sun, had a rectal temperature of 41.3 ºC. Over this time period, lambs were more likely to move to shade (HDI at 95%). From 00:00 to 06:00, despite the air temperature being lower than the hair-coat surface, favouring high rates of sensible heat loss to the environment, no lamb exhibited signs of hypothermia (rectal temperature < 37.5 ºC). In conclusion, haired newborn lambs coped well with high levels of radiant heat during the daytime and lower temperatures at night. However, providing access to shade during the daytime is important to improve the welfare of newborn lambs delivered in equatorial semi-arid regions.

Comparative assessment of growth performance, heat resistance and carcass traits in four poultry genotypes reared in hot-humid tropical environment.

This study investigated the impact of heat stress on growth and carcass traits in four poultry genotypes-Giriraja, Country chicken, Naked Neck and Kadaknath reared in a hot and humid tropical environment. Birds from all genotypes had ad libitum access to feed and water while being challenged with consistently high environmental temperatures in the experimental shed. Daily diurnal meteorological data were recorded inside and outside the shed. The study specifically examined growth variables and carcass characteristics. Significant differences (p < 0.01) were observed in body weight and average daily gain at various intervals. Notably, feed intake showed significant differences (p < 0.01) across weeks, indicating interactions between genotypes and time intervals. The feed conversion ratio (FCR) varied significantly (p < 0.01), with the highest FCR recorded in the Kadaknath breed. Livability percentages were similar across groups, except for Giriraja, which had significantly lower livability (p < 0.01). Carcass traits, including dressing, wings, feathers and giblet percentages, showed significant differences among genotypes (p < 0.01). Hepatic mRNA expression of growth-related genes revealed numerical variations, with Naked Neck displaying the highest (p < 0.05) fold change in IGF-1 expression compared to other genotypes. The study recognized in the Naked Neck genotype to possess higher resilience in maintaining homoeostasis and uncompromised growth under heat stress, providing valuable insights for sustainable poultry farming in challenging environmental conditions.

Comparative assessment of growth performance of indigenous and cross-bred calves subjected to combined stressors (heat and nutritional).

This study evaluated the impact of combined stressors (heat and nutritional stresses) on the growth and adaptive capability of Sahiwal (SW) and Karan Fries (KF) calves during the summer season. Calves in each breed were randomly divided into four groups. In SW breed the groupings were as follows: SWC (n = 4; Sahiwal Control); SWHS (n = 4; Sahiwal Heat Stress); SWNS (n = 4; Sahiwal Nutritional Stress) and SWCS (n = 4; Sahiwal Combined Stresses). Likewise, in the KF breed, KFC (n = 4; Karan Fries Control); KFHS (n = 4; Karan Fries Heat Stress); KFNS (n = 4; Karan Fries Nutritional Stress), and KFCS (n = 4; Karan Fries Combined Stresses). Control (C) and Heat Stress (HS) calves were fed ad libitum while Nutritional Stress (NS) and Combined Stresses (CS) calves were fed restricted feed (50% of C calves of respective breed) to induce nutritional stress in both the breeds. SWHS, SWCS, KFHS, and KFCS were exposed to summer heat stress from 1000 to 1600 h. All growth and adaptation variables were recorded at fortnightly intervals. Respiration rate, pulse rate, and rectal temperature during the afternoon were significantly (P < 0.01) higher in the CS group in both breeds. Further, CS had significantly (P < 0.05) higher plasma growth hormone and cortisol levels. Insulin-like growth factor-1, Triiodothyronine, and Thyroxine levels significantly decreased (P < 0.05) in the CS group in both breeds. Interestingly, heat stress didn't affect SWHS and KFHS bodyweight, however, a significant (P < 0.05) decrease in body weight of SWCS and KFCS was observed when compared with C. Hepatic mRNA expression of growth hormone, insulin-like growth factor-1, and growth hormone receptor significantly (P < 0.05) varied when compared between C and CS groups in both the breeds. The overall magnitude of stress was more pronounced in KF compared to the SW breed. This study concludes that when two stressors occur concurrently, they may have a greater influence on the adaptive capability of calves. Further, SW had better tolerance levels than KF, confirming the indigenous breed's superiority over cross-bred.

Heat stress and poultry production: impact and amelioration.

Globally, the poultry industry is gaining significant importance among the agricultural and its allied sectors. However, heat stress was found to negatively affect the poultry production particularly in the tropical regions. This review is therefore an attempt to generate information pertaining to the impacts of heat stress on poultry production and its amelioration. Heat stress reduces the growth, reproductive performance, and egg production in poultry birds. The reduction in productive potential of poultry birds on exposure to heat stress may be attributed to the deviation of energy resources from production to adaptation pathway. There are different approaches pertaining to relieving the adverse impacts of heat stress on poultry production. These approaches can be broadly categorized under genetic, management, and nutritional strategies. These approaches may reduce the negative effects of heat stress and enhance the productive performance of poultry birds. The management strategies include appropriate shelter design, providing shade, using sprinklers, implementing cooling devices, and using fans and ventilation systems. The recommended floor space for mature birds weighing 1.7 kg is 0.06 m2/bird while it is 0.13 m2/bird for the birds weighing 3.5 kg with 27.8 kg/m2 bird density in either case. The nutritional interventions comprise ration balancing and providing essential micronutrients to improve the productive and reproductive performance in poultry birds. Fat, antioxidants, yeast, and electrolyte supplementations are some of the most commonly used nutritional strategies to ensure optimum production in the poultry industry. Furthermore, providing adequate water supply and disease surveillance measures may help to ensure optimum meat and egg production in the birds. The advanced biotechnological tools may aid to identify suitable genetic markers in poultry birds which might help in developing new strains of higher thermo-tolerance by designing suitable breeding program involving marker-assisted selection. These strategies may help to optimize and sustain poultry production in the changing climate scenario.

Goat as the ideal climate-resilient animal model in tropical environment: revisiting advantages over other livestock species.

In the agriculture sector, livestock are considered extremely resilient to climate change and are tipped to play a significant role in ensuring food security to meet the increased demands of growing human population by 2050. Compared to other domestic species, goats are considered the ideal animal model for climate change due to its high thermal and drought resilience, ability to survive on limited pastures, and high disease resistance. This review is therefore a revisit to the advantages of rearing goats over other livestock species under current and future trends of changes in climate, particularly to cope with recurrent multiple stressors such as heat load, and lack of water and feed. In summary, goats, also called as poor man's cow, are preferred by the small-scale landless farmers due to their low input and assured higher output system, as they require low initial investment, with minimum specialized facilities and labors. Furthermore, they perceive goats as better resilient animal to cope with multiple stressors such as heat load, and water and feed scarcity, and possess better skills to cope with bush, when compared with sheep and cattle. The unique capacity for employing behavioral plasticity and morphological features of goats gives them clear advantage over sheep and cattle, when coping with seasonal biotopes, and experiences of water and feed shortage. When facing with low-quality feed, they also are superior to cattle and sheep to digest dry matter and to recycle nitrogen. Additionally, goats have superior ability to desiccate feces and concentrate urine, when compared with sheep and cattle. These advantages make goat the go-to species for efficiently countering the adversities associated with climate change and to optimize appropriate economic return through sustained production. Therefore, goats are tipped to be the future animals with extreme potential to counter the projected alarming climate change impacts and expected to play a significant role in ensuring food security to meet the demands of the growing human population by the end of this century.

Summer season induced changes in quantitative expression patterns of different heat shock response genes in Salem black goats.

Research efforts of elucidating the molecular mechanisms governing heat shock response which imparts thermo-tolerance ability to indigenous breeds are very scanty. Therefore, a study was conducted with the primary objective to determine the impact of heat stress on the expression pattern of different heat shock response genes in the hepatic tissues of indigenous Salem Black goat. The study was conducted for a period of 45 days in twelve 1-year-old female Salem Black breed goats. The animals were randomly allocated into two groups of six animals each, C (n = 6; Salem Black control) and HS (n = 6; Salem Black heat stress). The C animals were maintained in the shed in comfort condition while HS animals were exposed outside to summer heat stress between 10:00 h to 16:00 h during experimental period. The animals were slaughtered at the end of study and their liver samples were collected for assessing the different heat shock response genes. Based on the results obtained from the study it was established that the heat shock protein 70 (HSP70), HSP90, super oxide dismutase (SOD), nitrous oxide synthase 1 (NOS1) genes were significantly (P < 0.05) down regulated. However, heat stress did not influence the expression pattern of heat shock factor-1 (HSF1) gene. The lower level of expression of all heat shock response genes may be due to less magnitude of heat stress in the study to induce cellular stress response in Salem Black goats.

Effect of heat stress on the quantitative expression patterns of different cytokine genes in Malabari goats.

A study was conducted to determine the influence of exposure to hot environment on different cytokine gene expression patterns in Malabari goat. The study was conducted in 12 (10 months to 1 year old) goats of Malabari breed for 45-day duration. The control (n = 6; C) group goats were kept under comfortable condition in the shaded pens while heat stress (n = 6; HS) group goats were kept out in the open hot environment during summer season for the study duration between 10.00 h to 16.00 h. The representative mesenteric lymph node (MLN) samples were collected from the slaughtered goats at the end of study for assessing the different cytokine gene expression and histopathological changes. Compared with C group, the expression patterns of interleukin 18 (IL-18), tumor necrosis factor-α (TNF-α), interferon-ß (IFN-ß), and IFN-γ downregulated (P < 0.05) in the HS group. The histopathological changes of MLNs showed paucity of lymphocyte distribution in follicular areas as wells as decreased density of lymphocytes in the germinal centers of the HS group (P < 0.05). The findings from this study reflected the compromised immune functions during heat stress in Malabari goats. Further, the study established that IL-18, TNF-α, IFN-ß, and IFN-γ genes could serve as reliable immunological markers for quantifying heat stress-mediated immune response alterations in Malabari goats.

Prediction models, assessment methodologies and biotechnological tools to quantify heat stress response in ruminant livestock.

Livestock industries have an important role in ensuring global food security. This review discusses the importance of quantifying the heat stress response of ruminants, with an emphasis on identifying thermo-tolerant breeds. There are numerous heat stress prediction models that have attempted to quantify the response of ruminant livestock to hot climatic conditions. This review highlights the importance of investigating prediction models beyond the temperature-humidity index (THI). Furthermore, this review highlights the importance of incorporating other climatic variables when developing prediction indices to ensure the accurate prediction of heat stress in ruminants. Prediction models, particularly the heat load index (HLI) were developed to overcome the limitations of the THI by incorporating ambient temperature (AT), relative humidity (RH), solar radiation (SR) and wind speed (WS). Furthermore refinements to existing prediction models have been undertaken to account for the interactions between climatic variables and physiological traits of livestock. Specifically, studies have investigated the relationships between coat characteristics, respiration rate (RR), body temperature (BT), sweating rate, vasodilation, body weight (BW), body condition score (BCS), fatness and feed intake with climatic conditions. While advancements in prediction models have been occurring, there has also been substantial advancement in the methodologies used to quantify animal responses to heat stress. The most recent development in this field is the application of radio frequency identification (RFID) technology to record animal behaviour and various physiological responses. Rumen temperature measurements using rumen boluses and skin temperature recording using infrared thermography (IRT) are making inroads to redefine the quantification of the heat stress response of ruminants. Further, this review describes several advanced biotechnological tools that can be used to identify climate resilient breeds of ruminant livestock.

Evaluating rumen temperature as an estimate of core body temperature in Angus feedlot cattle during summer.

This study was conducted to determine the relationship between rectal temperature (TREC) and rumen temperature (TRUM) and to assess if TRUM could be used as a proxy measure of core body temperature (TCORE) in feedlot cattle. Eighty Angus steers (388.8 ± 2.1 kg) were orally administered with rumen temperature boluses. Rumen temperatures were recorded at 10-min intervals over 128 days from all 80 steers. To define the suitability of TRUM as an estimation of TCORE, TREC were obtained from all steers at 7-day intervals (n = 16). Eight feedlot pens were used where there were 10 steers per pen (162 m2). Shade was available in each pen (1.8 m2/animal; 90% solar block). Climatic data were recorded at 30-min intervals, including ambient temperature (TA; °C); relative humidity (RH; %); wind speed (WS; m/s) and direction; solar radiation (SR; W/m2); and black globe temperature (BGT; °C). Rainfall (mm) was recorded daily at 0900 h. From these data, temperature humidity index (THI), heat load index (HLI) and accumulated heat load (AHL) were calculated. Individual 10-min TRUM data were converted to an individual hourly average. Pooled mean hourly TRUM data from the 128-day data were used to establish the diurnal rhythm of TRUM where the mean minimum (39.19 ± 0.01 °C) and mean maximum (40.04 ± 0.01 °C) were observed at 0800 h and 2000 h respectively. A partial correlation coefficient indicated that there were moderate to strong relationships between TRUM and TREC using both real-time (r = 0.55; P < 0.001) and hourly mean (r = 0.51; P < 0.001) TRUM data. The mean difference between TREC and TRUM was small using both real-time (0.16 ± 0.02 °C) and hourly mean TRUM (0.13 ± 0.02 °C) data. Data from this study supports the hypothesis that TRUM can be used as an estimate of TCORE, suggesting that TRUM can be used to measure and quantify heat load in feedlot cattle.

Expression patterns of candidate genes reflecting the growth performance of goats subjected to heat stress.

The study is an attempt to elucidate the molecular mechanisms governing growth performance during heat stress in goats. The primary objective of the study was to establish the influence of heat stress on the expression patterns of different growth related genes in Malabari goats. The study was conducted for a period of 45 days in 12 Malabari goats randomly allocated into two groups: MC (n = 6; Malabari control) and MHS (n = 6; Malabari heat stress). At the end of study period, all 12 animals were slaughtered and their liver tissues were collected for gene expression and histopathological studies. The temperature-humidity-index (THI) inside the shed (74.9) proved that the animals were not stressed while in the outside environment (86.5) the animals were extremely distressed. The hepatic growth hormone (GH), growth hormone receptor (GHR), insulin-like growth factor-1 (IGF-1), leptin (LEP) and leptin receptor (LEPR) gene expression patterns were significantly (P < 0.05) lower in heat stress group as compared to the control group animals. In addition, negative correlation (P < 0.05) was also established between THI and all the growth related gene expression in the study. The hepatic histopathological section showed more fatty and degenerative changes (P < 0.05) in hepatocytes in MHS group as compared to MC group. The study offers the first thorough insight into the expression patterns of different growth related genes during heat stress exposure in goats. Further, the study established GH, GHR, IGF-1, LEP, LEPR genes to be the ideal markers to reflect growth potential in Malabari goats.

Resilience of three indigenous goat breeds to heat stress based on phenotypic traits and PBMC HSP70 expression.

The objective of this experiment was to evaluate the influence of summer heat stress on physiological and behavioral responses of Osmanabadi, Salem Black, and Malabari goats. The study also evaluated the differences in heat shock protein 70 (HSP70) expression pattern between these breeds. The study was conducted over 45 days during summer (April-May) using 36 1-year-old female goats by randomly allocating them into six groups with six animals in each group: Osmanabadi control (Osmanabadi CON), Osmanabadi heat stress (Osmanabadi HS), Malabari control (Malabari CON), Malabari heat stress (Malabari HS), Salem Black control (Salem Black CON), and Salem Black heat stress (Salem Black HS). The Osmanabadi CON, Malabari CON, and Salem Black CON animals were housed in a shed while the Osmanabadi HS, Malabari HS, and Salem Black HS groups were subjected to heat stress by exposing them to outside environment between 1000 and 1600 h during the experimental period. All 36 animals were provided with ad libitum feed and water. The data generated were analyzed by general linear model (GLM) repeated measurement analysis of variance. Results indicated that the drinking frequency (DF) was higher (p < 0.01) in heat stress groups (12.58, 12.25, and 10.75 times for the Osmanabadi HS, Malabari HS, and Salem Black HS, respectively) as compared to their respective control groups (5.67, 6.25, 5.58 times for the Osmanabadi CON, Malabari CON, and Salem Black CON, respectively). Water intake (WI) also showed similar trend to DF. The urinating frequency also (UF) differed between breeds with lower value (p < 0.05) recorded in the Salem Black HS (1.5 times) compared to the Malabari HS (2.92 times). The highest (p < 0.05) rumination time (RuT) was recorded in the Malabari HS (48.00 min) than both the Osmanabadi HS (20.91 min) and Salem Black HS (23.67 min). The heat stress increased (p < 0.05) all physiological variables at 1400 h. The findings of this study suggest RR, RT, and PBMC HSP70 are reliable biological markers for evaluating thermo-tolerance capacity of indigenous goat breeds.

Short communication: using infrared thermography as an in situ measure of core body temperature in lot-fed Angus steers.

Thirty-six Black Angus steers were used in a replicated study; three replicates of 12 steers/replicate. Steers had an initial non-fasted BW of 392.3 ± 5.1, 427.5 ± 6.3, and 392.7 ± 3.7 kg for each replicate, respectively. Steers were housed outside in individual animal pens (10 m × 3.4 m). Each replicate was conducted over a 6-day period where infrared thermography (IRT) images were collected at 3-h intervals, commencing at 0600 h on day 1 and concluding at 0600 h on day 6. Rumen temperatures (T RUM) were measured at 10-min intervals for the duration of each replicate using a radio-frequency identification (RFID) rumen bolus. These data were used to determine the relationship with surface temperature of the cattle, which was determined using IRT. Individual T RUM were converted to an hourly average. The relationship between T RUM and surface temperature was determined using Pearson's correlation coefficient. There were no linear trends between mean hourly T RUM and mean surface temperature. Pearson's correlation coefficient indicated that there were weak associations (r ≤ 0.1; P < 0.003) between T RUM and body surface temperature. These data suggest that there was little relationship between the surface temperature and T RUM.

Adaptation strategies of yak to seasonally driven environmental temperatures in its natural habitat.

The gradual increase of ambient temperature (TA) at high altitude can cause heat stress as an effect of climate change and may shift the traditional habitat of yak to further higher altitude. Therefore, an attempt has been made in this study to evaluate the thermo-adaptability of yaks to different seasons at high altitude. The adaptive capabilities of yaks were assessed based on different heat tolerance tests in relation to changes in rectal temperature (RT; °F), respiration rate (RR; breaths/min), pulse rate (PR; beats/min), and plasma heat shock protein (HSP) profile. The experiment was conducted in 24 yaks, divided into three groups based on age as calf (n = 8), adult (n = 8), and lactating cow (n = 8). Thermal adaptability was determined by temperature humidity index (THI), dairy search index (DSI), and Benezra's thermal comfort index (BTCI) along with HSP70 profile. The THI was higher (P < 0.01) in summer than winter which increased from lowest (40.87) to highest (61.03) in summer by 20 points, where yaks were under heat load beyond THI 52. The RT (100.09 ± 0.18 °F), RR (21.76 ± 0.18), and PR (59.78 ± 0.32) increased by 23-35%, and this was correlated to the higher values of DSI exceeding 1 in calves (1.35 ± 0.03), lactating cows (1.29 ± 0.04), and adults (1.23 ± 0.32) during summer in comparison to winter (0.98 ± 0.02). The BTCI also showed values greater (P < 0.01) than 2 in calves (3.47 ± 0.27), lactating cows (3.23 ± 0.28), and adults (2.98 ± 0.29) which reflected 49-75% increase in rectal temperature and respiration rate during summer. Further, heat stress was substantiated by threefold higher (P < 0.01) level of plasma HSP70 in calves (189.61 ± 3.90 pg/ml) followed by lactating cows (168.62 ± 3.03 pg/ml) and adults (155.33 ± 2.30 pg/ml) against the winter average of 87.92 ± 3.19 pg/ml. Present results revealed that yaks were experiencing heat stress in summer at an altitude of 3000 m above sea level and calves were more prone to heat stress followed by lactating cows and adults.

Comparative assessment of growth performance of three different indigenous goat breeds exposed to summer heat stress.

A study was conducted to assess comparatively the growth performance of three different indigenous goat breeds during exposure to summer heat stress. The primary objective of the study was to observe the heat stress impact on the growth performance based on the body weight changes, allometric measurements, growth hormone (GH) concentration and peripheral blood mononuclear cell (PBMC) Insulin-like growth factor-1 (IGF-1) mRNA expression pattern during the summer season in comparison with the local breed (Osmanabadi). Thirty-six ten-month- to one-year-old female goats of Osmanabadi, Malabari and Salem Black breeds were randomly divided into six groups, OC (n = 6; Osmanabadi control), OHS (n = 6; Osmanabadi heat stress), MC (n = 6; Malabari control), MHS (n = 6; Malabari heat stress), SBC (n = 6; Salem Black control) and SBHS (n = 6; Salem Black heat stress). Body weight was recorded at weekly intervals, whereas other growth and allometric measurements and blood collection were carried out at fortnightly intervals. Breed factor significantly (p < .05) influenced only few growth variables such as body weight, body mass index (BMI) and body condition score (BCS). However, heat stress treatment significantly (p < .05) reduced all growth parameters expect BMI. Further, the heat stress significantly (p < .01) increased plasma GH concentration in goats with significantly higher (p < .05) concentration recorded in OHS. Among the stress groups, the lower (p < .05) PBMC IGF-1 mRNA expression was recorded in OHS, while the higher (p < .05) expression was observed in SBHS indicating the extreme adaptive capability of Salem Black breed. Thus, the results indicated that the Salem Black breed performed much better compared to both Osmanabadi and Malabari breeds indicating the superior ability of this breed to adapt to heat stress challenges. The results also indicated that plasma GH and IGF-1 gene may act as ideal biomarkers for assessing the heat stress impact on growth performance in indigenous goats.

Adaptive capability as indicated by behavioral and physiological responses, plasma HSP70 level, and PBMC HSP70 mRNA expression in Osmanabadi goats subjected to combined (heat and nutritional) stressors.

A study was conducted to assess the impact of heat and nutritional stress simultaneously on the adaptive capability as indicated by behavioral and physiological responses, plasma heat shock protein 70 (HSP70) level, and peripheral blood mononuclear cells (PBMC) HSP70 gene expression in goats. Twenty-four adult Osmanabadi bucks (average body weight (BW) 16.0 kg) were used in the present study. The bucks were divided into four groups viz., C (n = 6; control), HS (n = 6; heat stress), NS (n = 6; nutritional stress), and CS (n = 6; combined stress). The study was conducted for a period of 45 days. C and HS bucks had ad libitum access to their feed while NS and CS bucks were under restricted feed (30 % intake of C bucks) to induce nutritional stress. The HS and CS bucks were exposed to solar radiation for 6 h a day between 10:00 a.m. and 4:00 p.m. to induce heat stress. The data was analyzed using repeated measures analysis of variance. The standing time differed significantly (P < 0.01) between ad libitum fed groups (C and HS) and restricted feeding groups (NS and CS). The highest (P < 0.01) lying time was recorded in the CS group while the lowest in the C and HS groups. The highest (P < 0.01) drinking frequency was also recorded in the CS group. Water intake recorded was significantly (P < 0.01) higher in both the HS and CS groups. The highest respiration rate (RR), pulse rate (PR), and rectal temperature (RT) during the afternoon were also recorded in the CS group. Further, skin temperature of the head, flank, and scrotum during the afternoon was also higher (P < 0.01) in the CS group. In addition, both plasma HSP70 concentration and PBMC HSP70 messenger RNA (mRNA) transcript expression were also significantly (P < 0.01) higher in the CS group. It can be concluded from this study that when two stressors occur simultaneously, they may have severe impact on adaptive capabilities of Osmanabadi bucks as compared to that would occur individually. Further, the study indicated that lying time, drinking frequency, RR, RT, plasma HSP70, and PBMC HSP70 gene expression may act as ideal biological markers for assessing the impact of CS on adaptive capabilities in bucks.

Impact of heat stress, nutritional restriction and combined stresses (heat and nutritional) on growth and reproductive performance of Malpura rams under semi-arid tropical environment.

A study was conducted to assess the combined effect of heat stress and nutritional restriction on growth and reproductive performances in Malpura rams. Twenty-eight adult Malpura rams (average body weight (BW) 66.0 kg) were used in this study. The rams were divided into four groups: CON (n = 7; control), HES (n = 7; heat stress), NUS (n = 7; nutritional stress) and COS (n = 7; combined stress). The study was conducted for a period of 2 months. CON and HES rams had ad libitum access to their feed while NUS and COS rams were under restricted feed (30% intake of CON rams) to induce nutritional stress. The HES and COS rams were kept in climatic chamber at 42 °C and 55% relative humidity for 6 h a day between 10 : 00 h and 16 : 00 h to induce heat stress. Body weight increased significantly (p < 0.05) in CON as compared to NUS and COS. When compared within groups, scrotal width morning, scrotal width afternoon, scrotal circumference morning and scrotal circumference afternoon were significantly (p < 0.05) larger in CON while smaller in COS rams. The higher testicular length was recorded both during morning (p < 0.05) and afternoon (p < 0.01) in COS rams while the lowest in NUS rams. The highest plasma testosterone concentration was recorded in CON and lowest in COS rams. Semen volume and mass motility also differed significantly (p < 0.05) between the groups. The highest semen volume and mass motility was recorded in CON and NUS while lowest in both HES and COS rams. It can be concluded from this study that when two stressors occur simultaneously, they may have severe impact on reproductive performance of rams.

Maturation timing and fetal bovine serum concentration for developmental potential of sheep oocytes in vitro.

The success of in vitro embryo production (IVEP) in animals has improved over time, employing a variety of culture media. Here, we assessed the maturation timing and developmental potential of sheep oocytes in vitro at different concentrations of fetal bovine serum (FBS): Cumulus oocyte complexes (COCs) were aspirated from follicles (2-6 mm) of sheep ovaries collected from local slaughter house. COCs were randomly divided into two groups and matured at 38.5'C, 5% CO2 for 24 h (Group I) and 27 h (Group II). Oocytes cultured for 27 h showed significantly (P <0.05) more maturation than those cultured for 24 h (82 vs. 76%) followed by more cleavage (35 vs. 30%), morula (53 vs. 39%) and blastocyst (17 vs. 11%) percentage. In the second experiment, oocytes were randomly divided into two groups and matured with 10% FBS (Group I) and 20% FBS (Group II) for 27 h supplemented with pyruvate, glutamine, LH, FSH and estradiol. After maturation, oocytes were fertilized by fresh semen for 18 h. Presumptive zygotes in both the groups were again divided into two groups and culturedin 10 and 20% FBS during post fertilization period, respectively. Different FBS concentration in maturation medium did not influence maturation percentage (82 vs. 79%) significantly. Out of culture groups, presumptive zygotes matured in 20% FBS and cultured in 20% FBS during post fertilization period showed significant increase in cleavage percentage (44 vs. 39, 35 and 27%) as compared to other groups but subsequent development to morula (55 vs. 53, 43 and 40%) and blastocyst (20 vs. 17, 16 and 15%) percentage were more in the group matured in 10% FBS and cultured in 20% FBS during post fertilization period.

Effect of mineral mixture and antioxidant supplementation on growth, reproductive performance and adaptive capability of Malpura ewes subjected to heat stress.

This study was conducted to evaluate the effect of mineral and antioxidant supplementation on growth, reproductive performance and physiological adaptability of heat-stressed Malpura ewes. The study was conducted for a period of 21 days in 21 adult Malpura ewes. The ewes were randomly divided into three groups with seven animals each viz. GI (control; n = 7), GII (heat stress; n = 7) and GIII (heat stress + mineral and antioxidant supplementation; n = 7). The animals were stall fed ad libitum with the diet consisting of 70% roughage and 30% concentrate. GI ewes were maintained under normal controlled condition in the shed, while GII and GIII ewes were subjected to heat stress by exposing them to 42 °C in the climatic chamber. The parameters studied were feed intake (FI), water intake (WI), body weight, body condition score (BCS), physiological, biochemical and endocrine responses. Heat stress significantly altered FI, water intake, BCS, respiration rate and rectal temperature in the afternoon, oestrus duration, estradiol, progesterone, Hb, PCV, plasma glucose, total protein, cortisol, T3 and T4 levels while mineral and antioxidant supplementation ameliorated this heat stress effect on the parameters studied. Further, the adverse effect of heat stress on the productive and reproductive efficiency of Malpura ewes was reduced considerably by mineral mixture and antioxidant supplementation. This is evident from the non-significant difference in BCS, oestrus duration and plasma estradiol between GI and GIII in this study. Hence, it is very pertinent to conclude from this study that mineral mixture and antioxidant supplementation were able to protect Malpura ewes against heat stress.