Hot Dry Season Research Articles

Effect of commercially blended synbiotic product as a replacement for antibiotic growth promoters on growth performance and villi morphology of broiler chicks in dry hot season

Effect of commercially blended synbiotic product as a replacement for antibiotic growth promoters on growth performance and villi morphology of broiler chicks in dry hot season

L-serine modulates activities of antioxidant enzymes and behavioral responses in broiler chickens subjected to feed restriction during the hot-dry season

The aim of the study was to evaluate the effects of L-serine on catalase and glutathione peroxidase activities; latency, rest, number of lines crossed, attempts at jumping, vocalization, defecation, preening rate and tonic immobility of broiler chickens subjected to feed restriction during the hot-dry season. Broiler chicks (n =120) were divided into four groups of 30 each: Group A: feed restriction (FR); Group B: feed restriction + L-serine (FR + L-serine); Group C: feed ad libitum (AL); and Group D: feed ad libitum + L-serine (FR + L-serine). L-serine (200 mg/kg) was administered for 14 days orally from one-day old. Broiler chickens were subjected to 20%-feed restriction from day 7-14 of rearing. The temperature-humidity index recorded from the study period was 30.88 ± 0.81, indicating the chickens were subjected to environmental heat stress. At weeks 3, 4 and 5, serum catalase and glutathione peroxidase activities were evaluated. Tonic immobility and Open-field responses were assessed at weeks 4 and 5. Activities of catalase and glutathione peroxidase increased (P < 0.05) in FR + L-serine and AL + L-serine broiler chickens, compared to FR and AL broiler chickens. Latency duration, and rest and frequency of preening increased (P < 0.05) in FR and AL broiler chickens, compared to FR + L-serine and AL + L-serine broiler chickens. Tonic immobility decreased significantly (P < 0.05) in the following order: AL > FR > AL + L-serine > FR + L-serine broiler chickens. The results show that feed restriction and/or L-serine ameliorated the risk of adverse effects of environmental heat stress by increasing catalase and glutathione peroxidase activities; and by decreasing duration of rest, preening frequency, latency of movement and tonic immobility. In conclusion, L-serine administration and feed restriction, particularly in combination, alleviated the adverse heat stress-induced behavioral responses partly by enhancing activities of catalase and glutathione peroxidase.

Diversity of freshwater fish at Sago Palm Wetlands, Nakhon Si Thammarat Province, Thailand

Abstract. Suriya C, Satian C, Visut B, Supadha K. 2022. Diversity of freshwater fish at Sago Palm Wetlands, Nakhon Si Thammarat Province, Thailand. Biodiversitas 23: 6335-6344. Studies on the diversity of freshwater fish at Sago Palm Wetlands, Nakhon Si Thammarat Province, Thailand, were conducted in the period from March 2020 to November 2020. Fish samples were collected, encompassing the hot-dry season (March to June) and the rainy season (September to November) at 4 sampling zones, with 5 stations for each zone. Fish were caught using a seine net of 1 cm mesh size, 1.5m in length, and 1m in width. All data were analyzed to find out the fish diversity indices. The multivariate method was used to determine cluster analysis. A total of 3634 fish specimens, representing 62 species belonging to 24 families, were recorded during the sampling period. Cyprinidae was the major family, with Trichopsis vittatus containing the highest index of relative importance (IRI). The species diversity index of fish was in the range of 0.66 to 2.67; the evenness index was in the range of 0.64 to 0.95, and the species richness index ranged from 0.36 to 6.86, indicating an intermediate-low uniformity, with a medium species number in the area. The cluster analysis of the Bray-Curtis similarity index shows A division of the fish community into 2 clusters in the hot-dry season and 3 clusters in the rainy season, having a similarity percentage ranging between 42% and 95%, respectively. Also documented were one introduced species and one endangered fish species during sampling. The findings suggest that Sago Palm Wetlands is still inhabited by numerous fish species and should be conserved to ensure its aquatic animal richness for the future. This data provides information about the fish habitat in the Sago Palm Wetlands and can be used to update the checklists of fish species in the Tapi River, the Pak Phanang River, and the Trang River Basins. It also can be useful for the planning of fishing activities and the provision of guidelines for future research and conservation purposes.

Melatonin modulates rectal and body surface temperatures and their circadian rhythmicity in donkeys (Equus asinus) subjected to packing during the hot-dry season.

The study aimed to evaluate the effects of melatonin administration on rectal and body surface temperature (RT and BST, respectively) responses and their circadian rhythmicity in donkeys subjected to packing (load carrying) during the hot-dry season. Twenty donkeys were divided into two equal groups randomly: Groups 1 (packing + melatonin) and 2 (packing-melatonin), subjected to packing and both covered 20km. The RT, BST, and thermal environmental parameters were measured before and after packing. The procedure was carried out three times within the week, one day apart. This was followed 16-h after the last (third) packing procedure by 27-h recording period of all the parameters at 3-h intervals. The RT (37.77 ± 0.1℃) recorded in packing + melatonin donkeys was lower (P < 0.05) than in (packing-melatonin) (38.29 ± 0.1℃) post-packing, while the BSTs in packing + melatonin donkeys were lower than in(packing-melatonin) donkeys, especially the neck (33.07 ± 0.6℃ vs 35.4 ± 0.7℃, respectively) and coronary band (30.58 ± 0.5℃ vs 33.38 ± 0.7℃, respectively) temperatures. In both groups 16-h post-packing, overall mean RT and BST values were not different, except the coronary band temperature (26.61 ± 0.8℃) that was lower (P < 0.05) in packing + melatonin donkeys than (packing-melatonin) donkeys (28.78 ± 1.4℃). Melatonin-exerted biphasic effects on circadian rhythms of RT and BSTs by reducing body temperatures during the photophase and increasing the values during the scotophase in pack donkeys. In conclusion, melatonin may enhance packing output in donkeys during the hot-dry season.

Spatial and Temporal Variations in Water Quality Along the Bua River, Malawi

Water quality in freshwaters is declining worldwide due to increases in human populations, expansion of agricultural activities, and climate change. There are quite a number of regions of the world, Africa inclusive, that are understudied, and little to no baseline information exists related to water quality. This study was focused on the Bua River in Malawi, which supports sustenance fishing and basic needs for local communities. A portion of the river has elevated levels of protection because it is found within the Nkhotakota Wildlife Reserve. The focus of this study was to understand the spatial-temporal variations of water quality at five sites in the Bua River from May 2018 to June 2020 capturing the three main seasons (warm wet, cool dry, and hot dry). Although other water quality parameters did not vary spatially. Spatially, the Bua River mouth registered the highest values of Soluble reactive phosphorus and the Bua River upstream had the lowest. However, there were greater temporal differences across seasons for water temperature, water pH, and chlorophyll a. For instance, chlorophyll-a was higher during the hot dry season (3.28 µgL-1) compared to the cool dry season (2.10 µgL-1) and warm wet season (1.91 µgL-1). Water transparency, as measured by secchi depth was lowest during the warm wet season, which coincides with higher concentrations in SRP. All measurements of salt content, Electrical Conductivity (EC), Total Dissolved Solids (TDS), and salinity) were higher during the hot dry season and correlated negatively with SRP. Similarly, bicarbonate and alkalinity were also higher during the hot dry season. Principle Component Analysis indicated that the parameters responsible for variations of Bua River water quality are mainly related to soluble minerals, water temperature, and surface runoff associated with agricultural activities and domestic waste accounting for 78.49 % of the total variance in the data set.

Effect of L-serine on circadian variation of cloacal and body surface temperatures in broiler chickens subjected to feed restriction during the hot-dry season

The study aimed to evaluate the effects of L-serine on circadian variation of body temperatures in feed-restricted broiler chickens during the hot-dry season. Day-old broiler chicks of both sexes served as subjects; comprising four groups of 30 chicks each: Group A: water ad libitum + 20% feed restriction (FR); Group B: feed and water ad libitum (AL); Group C: water ad libitum + 20% feed restriction + L-serine (200 mg/kg) (FR + L-serine); Group D feed and water ad libitum + L-serine (200 mg/kg) (AL + L-serine). Feed restriction was performed on days 7–14 and L-serine was administered on days 1–14. Cloacal and body surface temperatures, recorded by digital clinical and infra-red thermometers, respectively, and temperature-humidity index were obtained over 26 h on days 21, 28 and 35. Temperature-humidity index (28.07–34.03) indicated broiler chickens were subjected to heat stress. L-serine decreased (P < 0.05) cloacal temperature in FR + L-serine (40.86 ± 0.07 °C), compared to FR (41.26 ± 0.05 °C) and AL (41.42 ± 0.08 °C) broiler chickens. Peak cloacal temperature occurred at 15:00 h in FR (41.74 ± 0.21 °C), FR + L-serine (41.30 ± 0.41 °C) and AL (41.87 ± 0.16 °C) broiler chickens. Fluctuations in thermal environmental parameters influenced circadian rhythmicity of cloacal temperature; especially the body surface temperatures, positively correlated with CT, and wing temperature recorded the closest mesor. In conclusion, L-serine and feed restriction decreased cloacal and body surface temperatures in broiler chickens during the hot-dry season.

English

Rice paddy cultivation in Senegal is subject to climatic fluctuations that affect its vegetative development. Although climatic conditions are a concern, we hypothesized that the new rice paddy ISRIZ would be better adapted to these fluctuations and would allow double cropping. We studied the vegetative behavior according to the date and mode sowing under low temperatures. An experiment was carried out in a split-split plot design with sowings staggered every three weeks (18 dates), and two sowing modes (Broadcast, transplanting). Data collected included plant height, number of tillers, 50% flowering, 80% maturity. The results showed that the sowing date and method had significant effects on the morphology of the varieties. These effects were exacerbated by low temperatures, resulting in a lengthening of the cycle of the varieties. Some varieties performed well with flowering cycles of less than 100 days and are adapted to double cropping. The best planting period during the hot dry season is between February and March, while in winter, planting between July and August is recommended. In the cold, the practice of transplanting is better adapted. This study identified new varieties that could be adapted to the practice of double cropping in a context of climatic variability. Key words: Irrigated rice, sowing dates, low temperatures, double cropping.

Monitoring trophic status using in situ data and Sentinel-2 MSI algorithm: lesson from Lake Malombe, Malawi.

With excessive nutrient enrichment exacerbated by anthropogenic drivers, many standing water bodies are changing from oligotrophic to mesotrophic, eutrophic, and finally hypertrophic-negatively affecting ecosystem functioning, biodiversity, and human populations. Efforts have been devoted to developing novel algorithms for estimating chlorophyll-a (chl-a), cyno-blooms, and floating vegetation. However, to this date, little research has focused on freshwater lakes in the data-scarce Sub-Saharan African countries such as Malawi. We, therefore, estimated the trophic status of Lake Malombe in Malawi-a lake likely to be affected by eutrophication and algal bloom-emerging threats to freshwater ecosystem functioning globally-especially with the onset of climatic and anthropogenic drivers. We integrated in situ data with high-resolution Sentinel-2 Multispectral Imagery Analysis (MSI). We independently assessed the remote sensing technique using in situ data and tested the model at multiple stages. The scatter plot showed that most points were in the 95% confidence interval. The validation results between the measured in situ chl-a concentrations and the Sentinel-2 MSI-based chl-a retrieval had a root mean square error (RMSE) of 2.88µg/L. The chl-a concentrations retrieved from MSI images were consistent with in situ data, indicating that the normalized difference chlorophyll index (NDCI) algorithm estimated chl-a concentrations in Lake Malombe with acceptable accuracy. Dissolved oxygen (DO), sulfate (SO42-), nitrite [Formula: see text], soluble reactive phosphorous [Formula: see text]), total dissolved solids (TDS), and chl-a, except for temperatures from the hot-dry-season, cold-dry-windy-season, and rainy-season, were significantly different (P < 0.05). The Sentinel-2 MSI imagery analysis also depicted similar results, with high chl-a concentration reported in March (rainy season) and October (hot-dry season) and the lowest from May to August (cold-dry-windy season). On the contrary, the ANOVA results for water quality parameters from all five points had P > 0.05. The correlation matrix showed coefficients of (0.798 < r < 0.930, n = 30, P < 0.005), suggesting that Lake Malombe is homogenous. Our results demonstrate that integrating remote sensing based on MSI imagery and in situ data to estimate chl-a can provide an effective tool for monitoring eutrophication in small, medium, and large standing waterbodies-crucial information required to respond to global ecological and climaticdynamics.

A Retrospective Study on the Epidemiology of Anthrax Among Livestock from 2011 to 2020 in Awi Administrative Zone, Amhara Region, Northwest Ethiopia.

In Ethiopia, anthrax is the second most important zoonotic disease, next to rabies. Data quantifying occurrence and distribution of animal anthrax in Awi administrative zone of Amhara region, Ethiopia, are limited. Thus, this study was conducted to describe the distribution of animal anthrax between 2011 and 2020 in Awi zone. This study used secondary data of animal anthrax that occurred in the Awi zone and reported to the Regional and National Veterinary Authority between 2011 and 2020. A total of 1262 cases of anthrax in animals and 324 animals that died due to anthrax were reported. The highest number of anthrax cases were reported in 2012 (n = 671), sharing 48.9% of the 10-year animal anthrax reported. However, the highest number of animal death due to anthrax (n = 104) was reported in 2014. The overall case fatality rate of anthrax was 25.67% (n = 324). The highest animal anthrax cases (n = 984; 77.97%) and deaths (n = 259; 79.94%) were recorded in Bovine. The highest cases of anthrax were registered in May (n = 313), while no anthrax case was reported during December. The highest and lowest number of animal death due to anthrax were reported during July (n = 64) and January (n = 6), respectively. The highest number of anthrax cases was reported in the hot-dry season (n = 479; 37.96%) whereas the lowest was reported during the cold-dry season (n = 30; 2.38%). The current study revealed a considerable number of animal anthrax cases and deaths in Awi zone every year. Hence, it is necessary for practicing prevention strategies including immunization programs before the peak season of anthrax outbreaks.

Impact of road transportation on physiological and oxidative stress biomarkers in puppies: Beneficial effect of melatonin

Transportation stress is complex and can affect the welfare and health of animals. The study was aimed at investigating the impact of road transportation on puppies and the beneficial effects of melatonin supplementation. Fourteen (14) apparently healthy Nigerian indigenous breed of dogs (puppies) divided into two groups, group I (control) and group II (pretreated with Melatonin at 10 mg/kg) were transported by road during the hot-dry season. Vital parameters; respiratory rate (RR), pulse rate (PR) and rectal temperature (RT) were taken before, during and immediately after commencement of the journey. Blood sample was also collected from each puppy before and immediately after the journey, part of which was used to analyzed for some hematological parameters and oxidative biomarkers such as the concentration of malondialdehyde (MDA) and reduced glutathione (GSH) and the activities of superoxide dismutase (SOD) and catalase (CAT). The result revealed that road transportation caused moderate to severe stress on the puppies as observed with the discomfort index (DI) (27.75–34.64 oC). The dry-bulb temperature during the study period was 33.23 ± 0.13 oC, while the relative humidity was 73.85 ± 0.60%. The RT, PR and RR also increased significantly (p < 0.05) during and immediately after the transportation compared to before commencement of the transportation. The result further revealed that total leucocyte counts and Neutrophil:Lymphocyte ratio (NLR) were elevated immediately after the transportation. The MDA concentration was also significantly (P < 0.05) elevated immediately after the transportation compared to before commencement in the control group. The activities of SOD and CAT and the concentration of GSH was lowered immediately after the transportation compared to before commencement. Supplementation with melatonin before the transportation ameliorated the stress posed by road transportation on the puppies as can be observed in the lowering of the elevated RT, PR and RR, total leucocyte count, NLR and MDA concentration. Pretreated with melatonin also increased the depleted activities of SOD and CAT, and the concentration of GSH immediately after the transportation. The results showed that road transportation is stressful for puppies and supplementation with melatonin mitigated the stress posed on the puppies, probably through the ability of melatonin to scavenge reactive oxygen species generated during the transportation. The results further showed that melatonin may be used to enhance the welfare of puppies subjected to road transportation under adverse thermal conditions.

L-serine improves lipid profile, performance, carcass weight and intestinal parameters in feed restricted broiler chickens during the hot-dry season.

The study evaluated effects of L-serine on lipid profile, performance, carcass weight and small intestinal parameters in heat-stressed broiler chickens subjected to feed restriction. Broiler chickens were divided into four groups, comprising 30 each. Group 1, feed restriction (FR); Group 2, feed restriction + L-serine (200mg/kg) (FR + L-serine); Group 3, ad libitum (AL); Group 4, ad libitum + L-serine (200mg/kg) (AL + L-serine). L-serine was administered orally from days 1 to 14, and feed restriction was performed on days 7-14. Serum harvested from blood samples on days 21, 28 and 35 was evaluated for lipid profile. Feed and water intake, live weight gain, organ and carcass weight were measured. At 35days old, broiler chickens (n = 7) per group were sacrificed to evaluate small intestinal morphology. Temperature-humidity index in the pen (30.88 ± 0.81) was above thermoneutral zone, indicating that chickens were subjected to heat stress. Concentrations of low-density lipoprotein, total cholesterol and total triglycerides were lower (p < 0.05), while higher concentration of high-density lipoprotein was recorded in L-serine groups than in the controls. Feed intake and live weight gain on day 35 in L-serine groups were higher (p < 0.05) than in controls. In L-serine groups, liver, spleen, pancreas and heart weight were higher, but abdominal fat was lower than in FR and AL groups. Villus height:crypt height ratio and area of villus surface were highest in L-serine groups than any other group. In conclusion, L-serine decreased low-density lipoprotein, increased feed intake, live weight, organ and carcass weight, villus height:crypt height ratio and villus surface area.

Negative human–crocodile interactions in Kariba, Zimbabwe: data to support potential mitigation strategies

AbstractInteractions between people and wild animals often result in negative impacts, and different views on the management of such interactions can lead to conflicts. Both intentional and unintentional negative human–wildlife interactions are increasing problems in many places where people share space with wild animals. Here we focus on negative interactions between people and Nile crocodiles Crocodylus niloticus in and around Lake Kariba in Zimbabwe. In the study area, crocodile attacks on people occur frequently, leading to people being injured or killed, which in turn prompts retaliatory actions against crocodiles. However, despite the negative impact of such interactions on both people and crocodiles, little is known about the spatio-temporal patterns of crocodile attacks or environmental conditions under which attacks occur. We collected information about crocodile attacks on people that occurred during 2000–2020, including the date, time, season and location of attacks, the age of victims and the activities they were carrying out when attacks occurred, and water conditions during attacks. We analysed these data to discern patterns and trends of crocodile attacks on people. Attacks occurred in clear as well as turbid water, and nearly half of all reported attacks were at night or in the early morning. The locations with the highest number of recorded attacks were Nyanyana and Charara lakeside, and the fewest attacks occurred at Andora harbour. Most victims were 26–40 years old, and most were attacked in the dry-hot season, while they were fishing. Our findings can be used to design area-specific mitigation strategies to reduce negative human–crocodile interactions.

Seasonal and Spatial Variability of PM2.5 Concentration, and Associated Metal(loid) Content in the Toluca Valley, Mexico.

This study provides evidence of the seasonal and spatial variation of metal(lloid)s in particulate matter minor to 2.5 microns (PM2.5) in the Toluca Valley Metropolitan Area (TVMA), the fifth largest urban center in Mexico. Four sites were sampled between 2013 and 2014, which included urban and industrial areas, in the dry-cold (November-February) and dry-hot (March-May) seasons; PM2.5 was collected using high- and medium-volume samplers. Metal(lloid) concentrations in PM2.5 were analyzed using inductively coupled plasma‒mass spectrometry (ICP‒MS). The highest 24-hour PM2.5 concentration in the northern area was observed, and the PM2.5 concentrations were independent of the season. Five metal(lloid)s with a recovery percentage above 80% were considered to be reported (Co, Cr, Cu, Mn, and Sb). The maximum concentrations of metal(lloid)s were observed during the dry-cold season, and concentrations were up to one hundred or thousand fold with respect to the dry-hot season. The 24-hour PM2.5 and metal(lloid) concentrations exceeded national and international guidelines to protect population health.

The γ-index: A spline-based tool to define features of wet and dry seasons

In this study, we have developed a new approach to define features of wet and dry seasons, using the linear splines (LSI) model. A set of formulas have been elaborated including our "γ-index". This last, oscillates sensibly between 0 and 1 depending on observational data of stations. The wettest stations have the highest indices while the arid lands have the lowest ones. Moreover, two distinct types of dry seasons are described in this work. The first one is the most conventional type induced by high temperature (HDS: Hot-dry season). However, the second one, is mainly linked with a sustained lack of liquid water because of low temperatures (CDS: Cold-dry season), inducing a physiological dryness of species. Using machine learning algorithms, the LSI model also was able to accurately (90%) predict the different climate classes defined by Köppen. The obtained results were very coherent to reality and to Köppen-Geiger climate classifications. Using this index, we were also able to map out the most arid areas in Algeria and those that are less. In cold regions, the calculated γ-indices reveal low values, very similar to those recorded in arid regions. The results have shown also a gradual decrease when approaching poles or tops of high mountains revealing, thus, increasing dryness.

Seasonal changes in semen characteristics of pure and crossbred rabbit bucks fed graded levels of vitamin C under heat stress conditions

The experiment was carried out to investigate the effect of season and graded vitamin C levels on semen quality of rabbit bucks in the Northern Guinea Savanna of Nigeria. A total of 55 rabbit bucks consisting of 40 pure New Zealand White (NZW) and 15 New Zealand x California (NZW×CAL) crossbreds were used for the study. The duration of the study spanned the hot dry (March-May) and cool wet (June-August) seasons. The traits investigated were semen motility, concentration, volume, pH, colour, live and dead sperm. Results obtained showed that vitamin C had significant (p&lt;0.01) effect on semen characteristics. There was a progressive increase in semen motility, concentration and live sperm and decrease in dead sperm as vitamin C level increased. Semen volume deviated from this pattern while colour was consistent all through. The result on monthly variation indicated that volume increased during the months of March to May ranging between 1.32-1.43 ml while during the months of June to August, it oscillated between 0.41 - 0.95 ml. Sperm concentration significantly (p&lt;0.05) increased from the hot dry months (75.72-129.48x106) to the cool wet months (98.17-102.78x106) while colour remained consistent with an increase in live sperm cells. There was significant (p&lt;0.001) interaction between vitamin C level and season on sperm motility, concentration and live sperm being better in the hot dry (70.9%, 114.5x106, 85.31%) and cool wet (76.3%, 121.6x106, 90.14%) seasons on 400 mg/kg feed vitamin C. Sperm volume was higher on 100 mg/kg feed vitamin C in the hot dry (1.60 ml) and cool wet (0.98 ml) seasons and 400 mg/kg feed in the hot dry (1.57 ml) and cool wet (0.77 ml) than other levels. Based on the results, it is concluded that vitamin C improved the semen characteristics of rabbit bucks at 400 mg/kg feed during the hot dry season which translates to improved semen quality.

Pycnogenol improves kinematic parameters of donkeys (Equus asinus) subjected to packing during the dry season

The administration of pycnogenol (PYC) prior to physical exertion had earlier shown to improve gait variables after work. The aim of this study was to determine the effect of PYC on kinematic parameters of donkeys subjected to packing during the dry season. Ten male donkeys served as experimental subjects. Five donkeys were administered with PYC (10 mg/kg) in feed (test group) while another five donkeys were given feed only (control group) for one week pre-packing. Thermal environmental parameters of ambient temperature (AT), relative humidity (RH) and temperature humidity index (THI) were recorded. Kinematic parameters of speed (SP), stride length (SL), stride frequency (SF) and stride duration (SD) using videographic recordings 5 minutes post-packing with each animal walking at a self-selected speed were recorded. The THI values obtained pre- (95.4 ± 3.9) and during (85.3 ± 1.6) packing in the cold-dry season were significantly lower than the values of 148.8 ± 1.8 and 134.8 ± 1.1, respectively obtained during the hot-dry season. The speed recorded in test group (2.0 ± 0.3 m/s) was significantly (P &lt; 0.05) higher when compared to the value (1.3 ± 0.2 m/s) obtained in control group during the hot-dry season while, during the cold-dry season, the test group recorded a significantly (P &lt; 0.05) higher speed (1.3 ± 0.3 m/s) when compared with 1.0 ± 0.2 m/s recorded in control group.The increased speed recorded in the test group indicated that the group performed better as they were less fatigued when compared with the control group. Thus, PYC could be used as a potential agent in the management of fatigue in donkeys used for packing purposes in the region.

Impact of heat stress on follicular size, oestradiol concentration and oestrus expression in Nigerian Zebu cows

The study was conducted to evaluate the effect of heat stress on follicular size, oestradiol concentrations and oestrus expression in different seasons on Zebu cows. Twelve (n=12) matured, Zebu cows were utilized for over a year. The year was divided into 3 phases. Ambient temperature, relative humidity and rectal temperature were determined using. Cows were synchronized for oestrus. Ultrasonic follicular studies were carried out daily. Blood samples were collected after administration of a second dose of PFG2α to assess serum concentration of oestradiol. The enzyme-linked immunosorbent assay technique was used to determine the concentration of oestradiol. Oestrus activities were monitored by visual observation. Follicle diameters at 24 hr were lower (P&lt; 0.05) in the cold, dry season (6.34± 0.68 mm) than hot dry (8.09±0.52 mm) and the rainy season (8.62±0.9 mm). At 72 hr, follicular diameters were significantly higher P&lt;0.05 in the hot, dry season (17.01±1.41 mm) than cold dry (12.90±1.22 mm) and the rainy season (12.08±0.82 mm). Time to peak of oestradiol concentrations was shorter P&lt;0.05 in the cold, dry season (31.50±5.41 hr), followed by a hot, dry season (35.42±4.25 hr) and then rainy season (52.25±7.08 hr). The amplitude of oestradiol was higher P&lt;0.05 in the cold, dry season (39.13±5.27 pg/mL) than hot dry (19.50±2.52 pg/mL) and rainy seasons (17.63±1.89 pg/mL). Durations of proestrus oestradiol surges were significantly higher P&lt;0.05 in the rainy season (40.88±7.10 hr) followed by a hot, dry season (35.50±7.71 hr) and then cold dry season (24.25±3.27 hr.). The total number of mounting activities for two hr. was higher P&lt;0.05 in the cold, dry season (7.6±0.93/hr) followed by rainy season (6.2±1.28/hr) and then hot dry season (4.4±0.81/hr). In conclusion, the study showed that heat stress affected oestrus expression by lowering the number of mounts per hour, increasing follicular size and reducing oestradiol concentration of these cows.

Seasonal fog enhances crop water productivity in a tropical rubber plantation

• The effect of fog on rubber trees ( Hevea brasiliensis ) was quantified for 3 years. • Visibility, sap flux density and crop water productivity (WP c ) were studied. • Under the fog days, rubber trees were physiologically less active. • Carbon assimilation and evapotranspiration were suppressed but WP c enhanced by fog. • Dry seasonal fog can reduce water demand and alleviate drought stress. The rapid conversion of tropical rainforests into monoculture plantations of rubber ( Hevea brasiliensis ) in Southeast Asia (SEA) necessitates understanding of rubber tree physiology under local climatic conditions. Frequent fog immersion in the montane regions of SEA may affect the water and carbon budgets of the rubber trees and the plantation ecosystems. We studied the effect of fog on various plant physiological parameters in a mature rubber plantation in southwest China over 3 years. During the study period, an average of 141 fog events occurred every year, and the majority occurred during the dry season, when the temperature was relatively low. In addition to the low temperature, fog events were also associated with low vapor pressure deficit, atmospheric water potential, relative humidity and frequent wet-canopy conditions. We divided the dry season into cool dry (November-February) and hot dry (March-April) seasons and classified days into foggy (FG) and non-foggy (non-FG) days. During the FG days of the cool dry season, the physiological activities of the rubber trees were suppressed where carbon assimilation and evapotranspiration showed reductions of 4% and 15%, respectively, compared to the cool dry non-FG days. Importantly, the unequal declines in carbon assimilation and evapotranspiration led to enhanced crop water productivity (WP c ) on cool dry FG days but insignificant WP c values were found between FG and non-FG days of the hot dry season. Our results suggest that, by regulating plant physiology, fog events during the cool dry season significantly reduce water demand and alleviate water stress for the trees through improved WP c .

Prevalence and tick loads in Nguni cattle reared in different environmental conditions across four provinces of South Africa.

Background and Aim:In tropical and subtropical countries, ixodid ticks are among livestock’s most economically important ectoparasites. Although Nguni cattle from South Africa have adapted to harsh environments, it is unknown whether they will be resistant to ticks, and the diseases carried by ticks under various climatic conditions. Therefore, this study aimed to compare tick load and estimate the prevalence of different tick species among Nguni cattle under different environmental conditions.Materials and Methods:Tick counts were conducted monthly under natural challenges over 2 years on 586 Nguni cattle located at ARC-Roodeplaat and Loskop farms (warmer climate), Mukhuthali Nguni Community and the University of Fort Hare farms (cooler climate). The generalized linear model procedure of the Statistical Analysis System was used to analyze the data. It fitted the location (farm), sex, year, month or season, and animal age as covariates.Results:The tick species (relative prevalence) observed were as follows: Amblyomma hebraeum (42%), Rhipicephalus evertsi (22%), Rhipicephalus (Boophilus) spp. (16%), Rhipicephalus appendiculatus (11%), Hyalomma marginatum (5%), and Rhipicephalus simus (4%). Tick infestation was significantly affected by location, season, year, month of the tick counting and age of the animal. Loskop farm had the highest tick count (m = 30.69) and showed the largest variation in tick count. Compared to the other seasons, higher tick counts were seen during the hot-dry (September–November) and hot-wet (December–February) seasons. A. hebraeum was the dominant tick species across all four farms, followed by R. evertsi. The perianal region (under the tail head), the perineum and the belly body locations were the most preferred tick attachment sites.Conclusion:These results provide useful information for developing appropriate control strategies for ticks and tick-borne diseases in these provinces of South Africa. Further work must investigate the feasibility of genetic improvement for tick resistance.

Socio-environmental changes and rodent populations in lowland agroecosystems of the lower delta of the River Senegal, West Africa: results of observations over a decade, 2008-2019

In the context of food self-sufficiency, the River Senegal Valley has been undergoing profound environmental changes for several decades. Rice production has increased due to the development of vast irrigated perimeters, which has been accompanied by recurrent proliferations of rodent populations that are crop pests and reservoirs of zoonoses. The aim of our study was to determine the factors underlying these phases of increased rodent abundance over a ten-year (2008 to 2019) sampling period during the hot dry season (February-May). A total of 1,867 rodents of four species were captured, among which Arvicanthis niloticus and Mastomys huberti dominated. Our results showed that, during this season, rodent abundance (i) increases significantly with rainfall from the previous year, (ii) is higher in cultivated than in uncultivated plots, (iii) increases with plant cover, (iv) increases, for M. huberti, with the presence of open water. We showed that in an area that was first sparsely cultivated and then impacted by hydro-agricultural rehabilitation of irrigation and drainage infrastructure, the abundance of A. niloticus changed following this program, reaching the level of a nearby area that has been intensively cultivated for decades. Moreover, we showed that the proportion of adults among the captured individuals was lower in rice plots than in vegetable gardening fields and uncultivated plots. The breeding pattern of adult individuals was also affected by land use. Results suggest that uncultivated areas and vegetable gardening fields constitute refuge and breeding ground hotspots and would thus form a starting point for the invasion of rice fields. Following these results, we advocate for regular monitoring of rodent breeding and abundance patterns, with a special focus on these refuge areas, particularly during the hot dry season. We recommend implementing effective and sustainable science-based control strategies at national and community levels to keep rodent populations within tolerable limits.