Low Temperature-humidity Index Research Articles

EFFECTS OF CLIMATE CHANGE ON MILK YIELD AND MILK COMPOSITION IN THAI CROSSBRED HOLSTEIN COWS

The purpose of this research was to study effects of climate changes on milk yield and milk composition of Holstein crossbred . This study uses data recording total milk production per farm each day and milk composition (from 2013–2017): fat percentage (% Fat), protein percentage (% Pro), solid not fat percentage (% SNF) and total solid percentage (% TS) from 79 farmers in Mahasarakham Province, Thailand. The temperature and humidity data were obtained from records of meteorological center. Using temperature and relative humidity for calculate temperature humidity index (THI). The effects of THI on milk yield and milk composition were assessed by procedure REG using SAS. The study indicated that, the weather was hot and humid. The temperature ranged from 20.88 – 33.01 ° C. and average humidity was 72.59%. The highest THI (82.07) was in May. The relationship between THI and milk yield was negatively related. The slope value was -0.099, it meaning that when the THI value increased by 1 unit the milk yield decreased by 0.099 kg / cow / day. The THI group for effect of THI on milk yield and milk composition was set 4 groups (THI 1 = THI ≤70, THI 2 = 74 ≤THI 78). The highest THI effect on low milk yield. In contrast, low THI (THI 1 and THI 2) effect on high milk yields. The climate change, temperature and humidity increase effects on milk production of dairy cows to decrease.

PSXI-37 Differences in thermoregulation ability and genetic parameters of skin traits in Angus, Brahman and their Crossbreds

Abstract Thermoregulation is important for beef cattle but tends to be negatively correlated with production traits. The objective of this study was to determine the variation in core body temperature and to estimate genetic parameters of skin traits in Angus, Brahman, and different levels of crossbred heifers (n = 337) reared in hot and humid conditions. Core body temperature was recorded as vaginal temperature every 15 minutes for 5 consecutive days. Dry bulb temperature and relative humidity in the pasture were also measured every 15 min and used to calculate a temperature-humidity index (THI). Five mm skin biopsies were collected from the right side of sixth thoracic bone of each heifer. Cross-sections of biopsy samples with a thickness of 7 µm were stained with Hematoxilin–Eosin technique. The number and area of sweat and sebaceous glands, and the thickness of dermis and epidermis were determined using the ImageJ program. Data were analysed using PROC MIXED in SAS 9.4 with a model including the effect of breed, year, and their interaction. Genetic parameters were estimated using WOMBAT. Average core body temperature of Angus, 25%, 37.5%, 50%,75% and 100% Brahman were 39.50±0.05, 39.30±0.04, 39.15±0.05, 39.2±0.0, 39.03±0.05, 39.04±0.05, respectively. Brahman heifers had lower core body temperature compared to Angus heifers (P = 0.0006). Heifers with smaller and more numerous sweat glands had higher (P < 0.01) and more variable core body temperature (P < 0.0001). Heritability of core body temperature under high and low THI was 0.44±0.006 and 0.61±0.003, respectively. Dermis and epidermis thickness had the lowest heritability (0.231±0.002) and the highest heritability (0.75±0.007), respectively. Heritabilities for the number of sweat glands and total sweat gland area were 0.375±0.02 and 0.432±0.006, respectively. In conclusion, thermoregulation was highly correlated with breed composition, number of sweat glands and the average size of sweat glands.

Exposing dairy bulls to high temperature-humidity index during spermatogenesis compromises subsequent embryo development in vitro

The possible impact of natural heat stress on animal fertility is currently a major concern for breeding companies. Here, we aimed to address this concern by determining the effects of natural heat stress on the fertility of Holstein bulls located in the Netherlands. Semen samples were collected from six bulls at two locations in March 2016 (low temperature-humidity index (THI) group; maximum THI of 51.8 and 55 at their respective locations) or August (high THI group; maximum THI of 77.9 and 80.5 during meiotic and spermiogenic stages of spermatogenesis, 42 to 14 days prior to semen collection). The effect of heat stress on semen quality was assessed by sperm morphology, motility, reactive oxygen species production, lipid peroxidation, viability, and DNA fragmentation. Moreover, we evaluated the development of embryos generated in vitro by low and high THI semen, and determined inner cell mass/trophectoderm ratio, apoptotic cell ratio, and embryonic gene expression in day-8 blastocysts. An increase in cell death (propidium iodide-positive cells; P = 0.039) was observed in the high THI group (31.5%) compared to the low THI group (27.6%). Moreover, a decrease (P < 0.001) was observed in the total blastocyst rates at day 7 post-insemination (15.3 vs 20.9%) and day 8 (23.2 vs 29.6%) in the high THI compared to the low THI group, respectively. There were no differences in the relative abundance of candidate transcripts examined. In conclusion, sperm samples from dairy bulls obtained during a period with higher THI had reduced viability and led to a decrease in blastocyst development and delayed hatching, compared to semen collected during a period with low THI.

Alpha lipoic acid supplementation ameliorates the wrath of simulated tropical heat and humidity stress in male Murrah buffaloes.

A supplement which ameliorates temperature-humidity menace in food producing livestock is a prerequisite to develop climate smart agricultural packages. A study was conducted to investigate the heat stress ameliorative efficacy of alpha lipoic acid (ALA) in male Murrah water buffaloes (Bubalus bubalis). Eighteen animals (293.61 ± 4.66Kg Bwt) were randomly allocated into three groups (n = 6); NHSC (non-heat-stressed control), HS (heat-stressed) and HSLA (heat-stressed-supplemented with ALA@32mg/kg Bwt orally) based on the temperature humidity index (THI) and ALA supplementation. HS and HSLA were exposed to simulated heat challenge in a climatically controlled chamber (40°C) for 21 consecutive days, 6h daily. Physiological responses viz. Respiration rate (RR), Pulse rate (PR) and Rectal temperature (RT) wererecorded daily before and after heat exposure. Blood samples were collected at the end of heat exposure on days 1, 6, 11, 16, and 21 and on day 28 (7th day post exposure which is considered as recovery) for peripheral blood mononuclear cells (PBMCs) separation, followed by RNA and Protein extraction for Real time quantitative PCR and Western blot analysis respectively, of heat shock proteins (HSPs). Two-way repeated measure ANOVA was performed between groups at different experimental periods. RR (post exposure) in HS and HSLA was significantly higher (P < 0.05) than NHSC from day 1 onwards but HSLA varied significantly from the HS 8th day onwards. Post exposure RT and PR in both HS and HSLA varied (P < 0.05) from NHSC throughout the study; but between HS and HSLA, RT significantly varied on initial 2days and last 6days (from days 16 to 21). HSP70 mRNA expression significantly up regulated in high THI groups with respect to the low THI group throughout the experimental period. During chronic stress (days 16 and 21) HSP70 significantly (P < 0.05) increased in HS but not in HSLA (P > 0.05) with respect to NHSC. ALA supplementation up-regulates and sustains (P < 0.05) the expression of HSP90 in HSLA in comparison to the HS and NHSC. HSP105 expression was significantly up-regulated (P < 0.05) in HS on days 16 and 21 (during long-term exposure) but only on day 21 (P < 0.05) in HSLA. HSP70, HSP90, and HSP105 protein expression dynamics were akin to the mRNA transcript data between the study groups. In conclusion, supplementing ALA ameliorates the deleterious effect of heat stress as reflected by improved physiological and cellular responses. ALA supplementation improved cellular antioxidant status and sustained otherwise easily decaying heat shock responses which concertedly hasten the baton change from a limited window of thermo tolerance to long run acclimatization.

Genetic parameters for hair characteristics and core body temperature in a multibreed Brahman-Angus herd1.

Thermal stress in hot humid conditions limits cattle production. The objectives for this study were to estimate genetic parameters for hair characteristics and core body temperature under low and high temperature humidity index (THI) conditions. Hair samples were collected and measured for length and diameter. Core body temperature was measured as vaginal temperature every 15 min over a 5-d period using an iButton temperature measuring device implanted in a blank CIDR in 336 heifers from the University of Florida multibreed herd (ranging from 100% Angus to 100% Brahman). Restricted maximum likelihood procedures were used to estimate heritabilities from multiple bivariate animal models using the WOMBAT program. Estimates of heritability for hair diameter, undercoat length, topcoat length, body temperature under low THI conditions, and body temperature under high THI conditions were 0.50, 0.67, 0.42, 0.32, and 0.26, respectively. The genetic parameters estimated in this study indicate a large, exploitable genetic variance which can be selected upon to improve tolerance in cattle. Breed effects for differing compositions of Brahman and Angus were also estimated. As Brahman breed composition increased by 25% undercoat length, topcoat length, body temperature under low THI conditions, and body temperature under high THI conditions decreased by 1.32 mm, 2.94 mm, 0.11 °C, and 0.14 °C, respectively. Under both low and high THI conditions, cattle with 25% Brahman breed composition or greater maintained a significantly lower body temperature than the 100% Angus breed group. The incorporation of Brahman germplasm is recommended for herds that often experience heat stress conditions in order to increase resilience to heat stress.

Infrared thermography measured body surface temperature and its relationship with rectal temperature in dairy cows under different temperature-humidity indexes.

The aim of this study was to better understand the inflection point of RT and BSTs and measure different body surface temperatures (BSTs) under different temperature-humidity index (THI) conditions. A total of 488 Holstein dairy cows were chosen to manually measure rectal temperature (RT) and BSTs including left side of eye, ear, cheek, forehead, flank, rump, fore udder, and rear udder by infrared thermography for 14 times. Those measurements included six times under high THI (THI > 78), three times under moderate THI (72 ≤ THI ≤ 78), and five times under low THI (THI < 72). Results showed that BSTs were affected by THI conditions (P< 0.01). The THI conditions where mean and maximum forehead temperatures started to increase rapidly (71.4 and 66.8) were lower than that where RT started to increase rapidly (74.1). The correlation coefficients of mean and maximum forehead temperatures to THI were 0.808 and 0.740, and were 0.557 and 0.504 to RT, all showing the highest as compared to other region temperatures with THI and RT, respectively. Thus, we conclude that BSTs are more sensitive to thermal environment than RT, suggesting the variability of BST to reflect body core temperature. In addition, the forehead is a relatively reliable region to assess the heat stress reflecting RT compared to the eye, ear, cheek, flank, rump, fore udder, and rear udder regions.

Survival analysis and seasonal patterns of pregnancy outcomes in Egyptian buffaloes

The objective of this study was to analyze the survival patterns of pregnancy outcomes in Egyptian buffaloes under subtropical environmental conditions. The overall reproductive and production indices were performed on a total of 1224 records. The means of days at first AI postpartum, days open and calving interval of Egyptian buffaloes are 62.29, 83.13 and 395.1 days, respectively. The survival analysis of pregnancy outcomes in the present study was restricted to the first AI (576 first AI records). Compared to the low temperature-humidity index (THI), the conception rate (P/AI at 30 days) was significantly decreased at high THI level (OR = 0.45; p = 0.029), however, no significant variations were recorded between the referent (low) THI level and the moderate one (OR = 0.86; p = 0.673). Additionally, the pregnancy loss rate was significantly increased at a high THI level (OR = 2.43; p = 0.008). In comparison with the referent (primiparous) group, the conception rates were significantly increased in the M1 (2–5 parities; OR = 2.84) and M2 (>5 parities; OR = 4.06) multiparous groups (p = 0.007 and 0.004, respectively). The Egyptian buffaloes produce a relatively higher daily milk yield (>9 kg) have significantly lower conception rate compared with the referent (<7 kg) group (OR = 0.46; p = 0.046). However, the daylight length (continuous variable) had no significant effects on the conception (OR = 0.88; p = 0.298) and pregnancy loss (OR = 0.92; p = 0.608) rates. The Cox Proportional-hazards model for the hazard of pregnancy outcome (P/AI at 30 days) revealed that multiparous buffaloes had a higher hazard of pregnancy than primiparous buffaloes (HR = 2.37, p = 0.001). Moreover, buffalo cows calving in the summer and spring have a lower hazard of pregnancy than buffaloes calve in the winter season (HR = 0.57 and 0.76, p = 0.001 and 0.002, respectively). The current study indicates that Egyptian buffaloes have the ability to tolerate the thermal stress up to 80 THI values without deterioration of pregnancy outcomes. Moreover, primiparous or high producing buffalo cows may require more effective reproductive strategies as modulation of breeding plans to get calving in the winter and autumn seasons.

Lunar and climatic effects on boar ejaculate traits

There is evidence that phases of the moon affect wild animal behaviors including reproduction. There is, however, little evidence of moon phase effects on domestic livestock reproduction. This study investigated the effects of moon phase and climatic variables on boar ejaculate traits. Records of 4149 semen collections from boars of nine different breeds at one boar stud were used. The response variables were volume of ejaculate, concentration of sperm in the ejaculate, and number of doses obtained per ejaculate. Moon phase, greatest daily temperature (T), least daily T, average daily relative humidity (RH), temperature-humidity index (THI), season and the interaction of moon phase with season were analyzed at the day of collection and 45 days prior to date of collection as a proxy of initiation of spermatogenesis. For both dates analyzed season and the interaction of season with moon had significant effects (P < 0.05) on the volume of the ejaculate. Moon phase had a significant effect (P < 0.05) on volume of ejaculate at the day of collection. Sperm concentration was affected (P < 0.05) by the interaction of moon phase with season, high and low temperature, THI, RH and breed. Season had an effect (P < 0.01) on concentration of sperm at the initiation of spermatogenesis. For doses that could be used for AI that were obtained/ejaculate, there were effects of moon phase, season, the interaction between season and moon phase and breed (P < 0.05) at collection day and at the initiation of spermatogenesis. There was an interaction (P < 0.0001) between season and moon phase for volume of ejaculate, sperm concentration and number of doses obtained per ejaculate at date of collection and at day of initiation of spermatogenesis. The significant interaction of season and moon phase on boar semen traits suggests that to maximize productivity of modern swine production systems determining a collection schedule in some seasons relative to moon phase may be advantageous.

Correlation between blood, physiological and behavioral parameters in beef calves under heat stress.

ObjectiveThe performance, health, and behaviour of cattle can be strongly affected by climate. The objective of this study was to determine the effect of heat stress on blood parameters, blood proteins (haptoglobin [Hp]; heat shock protein 70 [HSP70]), rectal temperature (RT), heart rate (HR) and rumination time in Korean native beef calves.MethodsThirty-two Korean native beef calves were randomly assigned to 8 groups with 4 animals per group. They were kept in environmental condition with temperature-humidity index (THI) ranging from 70.01 to 87.72 in temperature-humidity controlled chamber for 7 days.ResultsTheir HR, RT, and serum cortisol and HSP70 levels were increased (p<0.05) in high THI compared to those at low THI. But, serum Hp level was decreased (p<0.05) in high THI compared to these at low THI. In addition, HR, RT, serum cortisol and HSP70 were positively correlated with THI (R2 = 0.8368, p<0.01; R2 = 0.6162, p<0.01; R2 = 0.581, p<0.01; R2 = 0.2241, p = 0.0062, respectively). There was also positive association between HR and cortisol (R2 = 0.4697, p<0.01). Similarly, RT and cortisol were positively associated (R2 = 0.4581, p<0.01). But, THI and HR were negatively correlated with Hp (R2 = 0.2157, p = 0.02; R2 = 0.3362, p = 0.003). Hematology and metabolites results were different among treatment groups. Standing position was higher (p<0.05) in the high THI group compared to that in the low THI group.ConclusionBased on these results, it can be concluded that HR, RT, blood parameters (Cortisol, HSP70, Hp) and standing position are closely associated with heat stress. These parameters can be consolidated to develop THI chart for Korean native beef calves.

Quantification of methane emissions from Murrah buffaloes fed different energy diets during various temperature humidity index periods in a tropical environment

The objective of the present study was to quantify the enteric methane emission in Murrah buffalo heifers at high (summer) and low (winter) temperature humidity index (THI) period fed different energy level diets. Thirty-six growing Murrah buffalo heifers of average bodyweight (158.51 ± 16.5 kg) were distributed into three groups of six animals each separated based on their bodyweight and fed for the period of 120 days each during summer (high THI, 78–85) and winter (low THI, 50–61). The animals were fed on three different levels of metabolisable energy (ME) content and the Control ration (T1) having ME content according to ICAR (2013) and T2 and T3 were having 115% and 85% ME than the Control respectively, in total mixed-based ration. The SF6 tracer gas technique was used to quantify the enteric methane emission by the animals. Methane emission (g/day) of Control and the high energy (T1 and T2) group was lower (P &amp;lt; 0.05) than the low energy (T3) fed group in both seasons. Methane losses as percentage of gross energy intake was lower (P &amp;lt; 0.01) during the winter season. However, in the low energy treatment group (T3) at both seasons these values are higher than the IPCC recommended value (6.5%) for calculation of national inventory of greenhouse gas emission from enteric sources. In between season average daily gain (kg) was higher (P &amp;lt; 0.01) in the winter season and among the treatment groups it was higher (P &amp;lt; 0.01) in the high energy group (T1, T2). Higher (P &amp;lt; 0.01) digestibility of dry matter, organic matter, neutral detergent fibre and acid detergent fibre was reported in the Control and high energy-fed group. Whereas in the summer season digestibility of dry matter, organic matter, crude protein and acid detergent fibre was higher (P &amp;lt; 0.01) than in the winter season. It can be concluded that energy levels significantly (P &amp;lt; 0.05) affect methane emissions and was lower in the Control and high energy-fed group (T1 and T2). However, while quantifying methane emission in changing THI period at different seasons it did not show any significant variation.

Influence of season, age and management on scrotal thermal profile in Murrah bulls using scrotal infrared digital thermography.

The aim of the present study was to examine the effects of non-genetic factors on scrotal thermographic profile viz., proximal pole temperature (PPT °C), mid pole temperature (MPT °C), distal pole temperature (DPT °C) and ocular temperature (OcT) of Murrah (Bubalus bubalis) breeding bulls. A total of 109 buffalo bulls, maintained at three semen stations (SS), were monitored for scrotal surface and ocular temperatures using infrared thermography twice daily during rainy, winter and summer seasons using an FLIR i5 infrared camera and temperatures were measured. Thermograms were analysed by FLIR QuickReport v.1.2 SP2 software. Statistical analysis revealed that semen station, season, temperature humidity index (THI), housing system and timing of observations had significant (P<0.05) effect on scrotal surface temperature (SST) and OcT. In SS-I, the PPT and MPT were significantly (P<0.05) higher as compared to SS-II and SS-III. THI had significant (P<0.05) effect on SST and OcT, whereas PPT (°C), MPT (°C), DPT (°C) and OcT (°C) values during high THI (>80.88; <0.05) period were higher as compared to medium THI period (70.06-80.88) and during low THI period (<70.06). Temperature gradient (TG) of the testes was significantly (P<0.05) higher during low THI period (4.50±0.06°C) as compared to medium THI (2.38±0.03°C) and high THI (1.61±0.05°C). Season of the year had a significant effect (P<0.05) on the SST and OcT. During the rainy season, PPT (34.50±0.09°C), MPT (33.44±0.12°C) and DPT (32.11±0.15°C) were significantly (P<0.05) higher as compared to winter and summer seasons. Age of the bulls had non-significant effect on SST and OcT but had a marked influence on thermal profile of scrotum. It could be concluded semen station, season, temperature humidity index, housing system and timing of observations had a significant influence on scrotal surface temperature. The monitoring of scrotal surface temperature by infrared thermography was found to be useful in evaluating the effects of thermal stress on physiology and health of buffalo bulls.

Association between ambient temperature and humidity, vaginal temperature, and automatic activity monitoring on induced estrus in lactating cows

The objective of this study was to determine the association between ambient temperature and humidity, vaginal temperature, and automated activity monitoring in synchronized cows. Lactating Holstein cows (n = 641; 41.5 ± 9.4 kg of milk/d) were fitted with leg-mounted pedometers, resulting in 843 evaluated activity episodes of estrus. Vaginal temperature was monitored using thermometers attached to an intravaginal device as part of a timed artificial insemination (TAI) protocol; vaginal temperature was recorded every 10 min for 3 d. Ambient temperature and relative humidity were monitored using an external thermometer placed in the center of each pen. Milk production and body condition score (BCS) data were collected at the time of thermometer insertion. All statistical analysis was performed in R (https://www.r-project.org/) using Pearson correlation, analysis of variance, and logistic regression. Heat stress was calculated based on the percentage of time the cow spent with a vaginal temperature ≥39.1°C (PCT39) 9 to 11 d before TAI, and was classified as high (≥22.9%) or low (<22.9%). The mean vaginal temperature was 38.9 ± 0.2°C, and the mean maximum and minimum vaginal temperatures were 39.7 ± 0.5°C and 38.0 ± 0.8°C, respectively, with an average amplitude of 1.71 ± 0.9°C. Mean relative increase (RI) of estrus walking activity was 237.0 ± 160%. Animals with low BCS had a lower RI compared with cows with medium BCS (260.31 ± 17.45% vs. 296.42 ± 6.62%). Cows in early lactation showed lower RI compared with mid- and late-lactation animals (265.40 ± 9.90% vs. 288.36 ± 11.58% vs. 295.75 ± 11.29% for early, mid, and late lactation, respectively). Temperature-humidity index (THI) conditions categorized as low (THI ≤65) were associated with greater RI compared with medium (>65 to <70) and high THI (≥70). We detected no significant effect of PCT39 or milk production on RI, whereas parity exhibited a tendency. Cows that displayed greater RI at estrus had greater pregnancies per artificial insemination (P/AI) than cows with low RI (27 vs. 20%) or no RI (27 vs. 12%). Primiparous cows had greater P/AI than multiparous cows (27 vs. 20%), and cows in early and mid lactation had improved P/AI than those in late lactation (26 vs. 22 vs. 16% for early, mid, and late lactation, respectively). An interaction was observed between PCT39 and THI on P/AI, where a subpopulation of cows with high PCT39 had decreased P/AI under high THI conditions, but no differences in P/AI were observed for high PCT39 cows under medium or low THI conditions (13 vs. 24 vs. 26%). Future research should aim to refine variables related to hyperthermia and to understand the effects of body temperature on estrus expression and pregnancy rates.

Relationship between Deck Level, Body Surface Temperature and Carcass Damages in Italian Heavy Pigs after Short Journeys at Different Unloading Environmental Conditions.

Simple SummaryTransport duration and thermal conditions can negatively affect pig welfare and carcass quality. The effects of short journeys (30 min) in different thermal-humidity conditions on the body surface temperature of live heavy pigs and carcass skin damage were examined. Body temperature increased with increasing Temperature Humidity Index (THI) class. The highest and lowest body surface temperatures were found in pigs located on the middle and upper decks, respectively. THI class significantly affected skin damage scores, which increased with increasing THI class. Even at relatively low temperatures and THI, the results of this study suggested the need to increase the control of environmental conditions in the truck during short-distance transport of pigs, in order to improve welfare and reduce loss of carcass value.In order to evaluate the relationships between deck level, body surface temperature and carcass damages after a short journey (30 min), 10 deliveries of Italian heavy pigs, including a total of 1400 animals from one farm, were examined. Within 5 min after the arrival at the abattoir, the vehicles were unloaded. Environmental temperature and relative humidity were recorded and a Temperature Humidity Index (THI) was calculated. After unloading, maximum temperatures of dorsal and ocular regions were measured by a thermal camera on groups of pigs from each of the unloaded decks. After dehairing, quarters and whole carcasses were evaluated subjectively by a trained operator for skin damage using a four-point scale. On the basis of THI at unloading, deliveries were grouped into three classes. Data of body surface temperature and skin damage score were analysed in a model including THI class, deck level and their interaction. Regardless of pig location in the truck, the maximum temperature of the dorsal and ocular regions increased with increasing THI class. Within each THI class, the highest and lowest body surface temperatures were found in pigs located on the middle and upper decks, respectively. Only THI class was found to affect the skin damage score (p < 0.05), which increased on quarters and whole carcasses with increasing THI class. The results of this study on short-distance transport of Italian heavy pigs highlighted the need to control and ameliorate the environmental conditions in the trucks, even at relatively low temperature and THI, in order to improve welfare and reduce loss of carcass value.

Impact of three THI levels on somatic cell count, milk yield and composition of multiparous Holstein cows in a subtropical region

In Egypt, cow's milk represents 52.11% of the total milk production. Climatic condition is mainly expected to impact the welfare and productive performance of livestock animals. Thus, we aimed to explore the impact of temperature-humidity index (THI) on somatic cell count (SCC), milk production and composition on daily milk test records (33600) of Holstein cows under subtropical Egyptian conditions with different levels of THI. Our results revealed that daily milk yield and composition (fat%, protein %, yielded fat, yielded protein and the percentage of lactose) were higher in low THI (31.91kg, 3.91%, 3.22%, 418kg, 349kg and 4.20%, respectively) when compared with high THI. SCC significantly increased 36% from low to high THI. In addition to, it was increased with advanced parities 231.11% from 2nd to 7th parities. At high THI level, SCC was negatively correlated with total MY (r=−0.12P<0.05), 305 MY (r=−0.16P<0.05), protein % (r=−0.15P<0.01), fat% (r=−0.14P<0.01) and lactose % (r=−0.26P<0.01). The current study concluded that dairy cows performance was better in most of the investigated parameters at low THI than those in high THI. Thus, indicating a detrimental effect of THI on both welfare and economic return.

Effects of temperature-humidity index on health and growth performance in Japanese black calves.

We evaluated the relationship between the temperature-humidity index (THI) and health and growth performance in Japanese black calves in Japan. Data were collected from medical records of 19,313 Japanese black calves aged up to 3months for correlation analysis with THI from July 2008 to June 2011. Data were also collected on the market weights of 57,144 Japanese black calves, and we calculated the body weight gain (BWG) of each calf based on body weight and age in days at the calf market. Analysis for the relationship between disease incidence and THI demonstrated a negative correlation (r = -0.54, p < 0.01). In addition, the mean disease incidence at THI of ≤50 was significantly higher than that at THI of ≥71. Analysis for the relationship between growth performance in calves and THI revealed that a lower THI during the month of birth was associated with a lower BWG at the calf market and that BWG with THI of ≤70 was significantly lower than that with THI of ≥71 (p < 0.05). In contrast, a higher mean THI during the third month after birth was associated with a lower BWG at the calf market, and BWG with THI of >75 was significantly lower than that with THI of ≤50 or THI ranging from 56 to 60 (p < 0.05). These results indicate that Japanese black calves are susceptible to a cold environment immediately after birth, whereas they are susceptible to a heat environment 3months after birth.

Seasonal variation in body mass index, cardinal physiological variables and serum thyroid hormones profiles in relation to susceptibility to thermal stress in goat kids

The influence of seasonal changes and susceptibility to thermal stress on body mass index (BMI), cardinal physiological variables (respiratory rate; RR, pulse rate; PR and rectal temperature; RT) and circulating thyroid hormone profiles (T3 and T4) was studied in Red Sokoto (n=60) and Sahel (n=60) goats during the cold-dry (CDS), hot-dry (HDS) and rainy (RAS) seasons. Using the RR, goats were grouped into cold stress susceptible (CSS) and cold stress tolerant (CST) phenotypes in the season with lower temperature humidity index (CDS) or heat stress susceptible (HSS) and heat stress tolerant (HST) phenotypes in the seasons with higher THI (HDS and RAS). Results revealed that the PR and RT were lower (P<0.05), while circulating thyroid hormones and BMI were higher (P<0.05) in Red Sokoto compared with Sahel goats. The RR, PR, RT and T3:T4 were significantly lower, while circulating T3 was higher during the CDS as compared with the HDS. Higher population of the goats were susceptible to cold and heat stress. Discriminant analysis showed higher misclassification of goats into HSS and HST phenotypes as compared with classification into CSS and CST phenotypes. The CSS phenotypes had significantly lower RT, but higher PR than the CST phenotypes. The HSS phenotypes had lower (P<0.05)T3 than the HST phenotypes. Total variation in susceptibility to thermal stress was mainly explained by the RT, T3 and PR. In conclusion, unlike RT, PR and T3, BMI seems to have less influence on the susceptibility of kids to thermal stress. In addition, this study demonstrates the role of the thermogenic effect of T3 in the susceptibility and tolerance of kids to thermal stress.

Expression of heat-shock protein 72 mRNA in relation to heart rate variability of Sahiwal and Karan-Fries in different temperature-humidity indices.

Aim:To investigate the effect of temperature-humidity index (THI) on the expression pattern of heat-shock protein 72 (HSP72) mRNA of Sahiwal and Karan-Fries (KF) cattle in different THIs.Materials and Methods:Five different periods of a year were selected based on combinations of Tmax/Tmin, viz., P1: <20°C/<10°C; P2: >20°C/<10°C, P3: <30°C/<15°C; P4: >35°C/<20°C, and P5: >35°C/>20°C. The THI was calculated from the records of temperature and relative humidity in different periods. Heart rate variability (HRV) was calculated from electrocardiogram records in different periods. HSP72 mRNA expression was estimated by reverse transcription polymerase chain reaction.Results:The THI recorded during P1, P2, P3, P4, and P5 were 55.5, 60.3, 70.1, 74.5, and 79.0, respectively. THI in P4 and P5 were stressful to animals. HSP72 mRNA expression increased during cold stress in P1 in Sahiwal and heat stress in P4 and P5 in both Sahiwal and KF. Sahiwal maintained increased HSP72 mRNA expression longer than KF without causing a significant change in HRV.Conclusion:Both low THI in winter and high THI in summer increased HSP72 mRNA of Sahiwal and KF without significant change in HRV. Thermotolerance of Sahiwal could be due to the maintenance of higher HSP72 expression longer than KF in prolonged heat stress in summer.

Effect of thermal stress on fertility and egg quality of Japanese quail

Heat stress is one of the major causes of a decreased performance of laying quail in tropical and subtropical countries. The aim of this study was to investigate the impact of temperature humidity index (THI) on fertility aspects, external and internal egg quality parameters in Japanese quail. One hundred and forty four (144) Japanese quail, 12 of weeks age, were used. Birds were divided randomly into three equal groups, control (at low THI, lower than 70), H1 (at moderate THI, 70–75) and H2 (at high THI, 76–80). Quail in the control and H1 groups had significant greater fertility (p=0.021) and hatchability % (p=0.037), compared with H2 group. Quail in the control group (at low THI) laid heavier egg weight with a higher external (egg weight (p=0.03), shell thickness, shell weight, eggshell ratio and eggshell density (p=0.001)) and internal egg quality score (albumin weight (p=0.026), yolk height (p=0.003), yolk index (p=0.039) and Haugh unit (p=0.001)). Otherwise, such quality traits were compromised in heat-stressed quail. At the high THI level, egg weight had a significant positive correlation with albumin weight (r=0.58, p<0.01), yolk weight (r=0.22, p<0.05), albumen ratio (r=0.17, p<0.05), yolk height (r=0.14, p<0.05) and yolk index (r=0.18, p<0.05), but was negatively correlated with yolk ratio (r=−0.15, p<0.05). Japanese quail exposed to heat stress (THI over 75) revealed drop in fertility indices and egg quality traits, indicating a detrimental policy of economic income.

Physiological and lactation responses of Egyptian dairy Baladi goats to natural thermal stress under subtropical environmental conditions

The objective of this study was to evaluate the impact of thermal stress on milk production and physiological traits of Baladi goats under subtropical Egyptian conditions. Sixty dairy Baladi goats were exposed to three different levels of temperature-humidity index (THI), including low (less than 70), moderate (over 70 and up to 80), and high levels (over 80). The influence of THI on the milk composition and physiological, hematological, and biochemical traits was investigated. Rectal temperature and respiration rate were significantly greater at the higher THI than at low and moderate THI (p = 0.016 and 0.002, respectively). Baladi goats had decreased daily milk yield in a rate of 27.3 and 19.3% at high THI level, compared with low and moderate THI, respectively (p = 0.031). On the contrary, no significant differences have been reported in protein, fat, and total solids percentages at different THI levels. Total leucocyte count, serum glucose, and total protein were significantly reduced at high THI in comparison with low and moderate THI levels (p = 0.043, 0.001, and 0.001, respectively). However, dairy goats maintained relatively stable estimates for erythrocytes count, hemoglobin, serum triglycerides, cholesterol, catalase, total antioxidant capacity, and triiodothyronine at different THI levels. Our results indicate that dairy Baladi goats can tolerate THI levels up to 80; however, variable reduction in milk yield and few biochemical (serum total protein and glucose) and hematological (leucocytes count) parameters have been reported at a THI level higher than 80.

The impact of crossbreeding Egyptian and Italian buffalo on milk yield and composition under subtropical environmental conditions.

Buffalo are the second most valuable species in the world for milk production and their milk prices have been based on fat and protein composition. The aim of the paper was to compare the milk yield and composition of pure Egyptian buffalo (EB) and their crosses with the Italian buffalo and to investigate the impact of temperature humidity index (THI) on milk yield and composition under subtropical stressful conditions. 516 lactating buffalo were used (152 EB; 176 F1 crosses 50% EB and 50% Italian buffalo and 188 back cross (BC) 75% EB and 25% Italian buffalo). The results revealed that, milk yield (5·79 and 10·32%) and peak yield (6·36 and 7·67%) were significantly higher in F1 and BC than in EB, respectively. BC had 7·74 and 3·67% significantly higher daily yield when compared with EB and F1, respectively. EB were robust in the hot condition as the only reduction was in the peak of milk production from 15·02 in low THI to 13·72 kg in high THI, but fat and total solids%, were increased from 5·61 and 16·31 THI in low to 7·01 and 17·59 in high THI, respectively. BC was similar to some extent to EB as their milk was similar to EB under sever hot climate conditions (2331·92 and 2327·50 kg, respectively). A statistically significant reduction in the average daily milk yields was detected only in F1 from 10·33 to 8·38 kg in low and high THI level, respectively. The current study showed that BC produced a higher milk with higher daily average milk yield and peak yield with some evidence of robust under sever hot condition which were approximately similar to EB. Thus, it is recommended to encourage the producers to increase the number of BC animals in their farm for improving the milk production to fulfil the demand of Egyptian markets.