No effects of huddling on core body temperature in rock hyrax,Procavia capensis

Huddling is a behavioural energy conservation mechanism that is widely used by many small endotherms at low ambient temperatures. Huddling has many benefits, including decreasing the metabolic cost of maintaining body temperature (T_b), reducing the amount of heat lost to the environment, and increasing the local temperature of the nest. To test the effects of huddling on T_b, 10 rock hyrax, Procavia capensis, were housed in outside cages in four groups, varying from one to four individuals. iButtons® were surgically implanted into each rock hyrax to record their T_b every 15 min from August to November. Despite considerable variations in ambient temperatures, the rock hyrax were found to display some degree of heterothermy by varying their mean T_b from 36.70 to 37.72°C (n = 10) but not allowing it to drop below 33.60°C or rise above 39.67°C. Contrary to what was predicted, rock hyrax did not display any significant effects of huddling on T_b, irrespective of group size.     

Studies on the Taxonomy of the South African Tectocepheidae Grandjean 1953 (Oribatei,Acari)

Mousebirds (Coliiformes) exhibit well-developed communal roosting behaviour as well as a pronounced capacity for facultative hypothermic responses. We recorded body temperature (T_b)) in speckled mousebirds (Colius striatus) under semi-natural conditions in outdoor aviaries, and examined interactions between behavioural and metabolic thermoregulation by experimentally manipulating food availability and communal roosting behaviour. When food was available ad libitum, mousebirds roosting in a cluster maintained approximately constant rest-phase T_b, with 32°C < T_b < 42°C. By contrast, rest-phase T_b in single mousebirds decreased at 0.5°C/hr and minimum rest-phase T_b was significantly lower than when clustering. When food availability was restricted, the mousebirds exhibited facultative hypothermic responses that were less pronounced in clustering groups (minimum rest-phase T_b = 33.3°C, circadian amplitude of T_b = 9.5°C) compared to single birds (minimum rest-phase T_b = 30.7°C, circadian amplitude of T_b = 11.8°C). When clustering, rest-phase T_b was highly synchronized among individuals. Our data reveal that communal roosting has profound consequences for rest-phase thermoregulation in C. striatus, and provide further insights into the potential role of physiological constraints in the evolution of avian sociality.     

Thermal biology and locomotor performance in Phymaturus calcogaster: are Patagonian lizards vulnerable to climate change?

Behavioral and physiological traits of ectotherms are especially sensitive to fluctuations of environmental temperature. In particular, niche-specialist lizards are dependent on their physiological plasticity to adjust to changing environmental conditions. Lizards of the genus Phymaturus are viviparous, mainly herbivorous, and inhabit only rock promontories in the steppe environments of Patagonia and the Andes. Herein, we examine the vulnerability of the southernmost Phymaturus species to global warming: the endemic Phymaturus calcogaster, which lives in a mesic environment in eastern Patagonia. We studied body temperatures in the field (T_b), preferred body temperatures in a thermogradient (T_pref), the operative (T_e) and environmental temperatures, and the dependence of running performance on body temperature. P. calcogaster had a mean T_b (27.04°C) and a mean T_e (31.15°C) both lower than their preferred temperature (T_pref = 36.61°C) and the optimal temperature for running performance (T_o = 37.13°C). Lizard activity seems to be restraint during the early afternoon due high environmental temperatures. However, both, the high safety margin and warming tolerance suggest that the expected increase in environmental temperatures due to global warming (IPCC report in 2018) would not threaten, but indeed enhance locomotor performance in this population.     

Temperature and mass scaling affect cutaneous and pulmonary respiratory performance in a diving frog

Global climate change is altering patterns of temperature variation, with unpredictable consequences for species and ecosystems. The Metabolic Theory of Ecology (MTE) provides a powerful framework for predicting climate change impacts on ectotherm metabolic performance. MTE postulates that physiological and ecological processes are limited by organism metabolic rates, which scale predictably with body mass and temperature. The purpose of this study was to determine if different metabolic proxies generate different empirical estimates of key MTE model parameters for the aquatic frog Xenopus laevis when allowed to exhibit normal diving behavior. We used a novel methodological approach in combining a flow-through respirometry setup with the open-source Arduino platform to measure mass and temperature effects on 4 different proxies for whole-body metabolism (total O₂ consumption, cutaneous O₂ consumption, pulmonary O₂ consumption, and ventilation frequency), following thermal acclimation to one of 3 temperatures (8°C, 17°C, or 26°C). Different metabolic proxies generated different mass-scaling exponents (b) and activation energy (E_A) estimates, highlighting the importance of metabolic proxy selection when parameterizing MTE-derived models. Animals acclimated to 17°C had higher O₂ consumption across all temperatures, but thermal acclimation did not influence estimates of key MTE parameters E_A and b. Cutaneous respiration generated lower MTE parameters than pulmonary respiration, consistent with temperature and mass constraints on dissolved oxygen availability, SA:V ratios, and diffusion distances across skin. Our results show that the choice of metabolic proxy can have a big impact on empirical estimates for key MTE model parameters.     

Heat production and dissipation in a South African diurnal murid Lemniscomys griselda

Heat production measured as oxygen consumption (V_O2 and heat dissipation calculated as the means of the overall thermal conductance were studied in a South African diurnal murid Lemniscomys griselda. This species maintains its body temperature (T_b) well at around 36,5 ± 1,0 °C over ambient temperatures (T_a) ranging between 5 and 34 °C. The thermoneutral zone lies between T _a = 30-34 °C. When exposed to temperatures below the low critical point L. griselda at rest conforms to Newton's law of cooling. Non-shivering thermo- genesis (NST) was studied as a response to an injection of noradrenaline (sc). Following the administration of 1,5 mg noradrenaline per kg body mass to an anaesthetized animal, an increase of 329% in VO₂ was recorded. The distribution pattern of L. griselda in comparison with that of Rhabdomys pumilio, the more common diurnal murid species in South Africa, is discussed.     

Regulatory Effects of Water Temperature on Loma salmonae (Microspora) Development in Rainbow Trout

Abstract

Water temperature, a pivotal factor influencing interactions between teleosts and pathogens, was examined to determine its effects on the kinetics of xenoma formation and dissolution subsequent to experimental exposure of rainbow trout Oncorhynchus mykiss to the microsporidian gill pathogen Loma salmonae. The permissive water temperature range in which xenomas developed was between 9° and 20°C. Parasite development was arrested at temperatures outside this range, as indicated by the absence of visible xenomas among exposed fish. In addition, when these trout were subsequently moved to temperatures within the permissive range, xenomas failed to develop. Water temperature, within the permissive range, had no significant effect on either the number of xenomas that formed or the proportion of fish that developed xenomas following gastric intubation with a standard dose of spores. The relationship between water temperature and xenoma onset-time was best described (R ² = 88.3%) by polynomial regression analysis: onset = 320 ? 33.4T + 0.9547T ², where T is temperature (°C). Xenoma onset rate was also described through a modified degree-days model, yielding a predictive equation appropriate for use under conditions of fluctuating temperature. The thermal units, expressed as days × (°C above 7°C) necessary for xenoma onset were 298.6 on average. Xenoma dissolution rates, from the time of onset, also appeared to have a trend; more rapid dissolution occurred as temperatures increased. However, this trend correlated minimally with regression models.     

Haemato-immunological and stress responses of Labeo rohita (Hamilton) fingerlings: effect of rearing temperature and dietary gelatinized carbohydrate

A feeding trial of 70‐days was carried out to study the haemato‐immunological and stress responses of Labeo rohita fingerlings reared at two water temperatures [ambient (Amb) – 27 °C and 32 °C] fed with graded levels of gelatinized corn carbohydrate (GC). Two hundred and sixteen fingerlings were randomly distributed into six treatment groups in triplicate. Three semi‐purified diets were prepared containing 30% crude protein with graded levels of GC 40%, 50% and 58%. The six treatment groups were T₁ (40% GC × Amb), T₂ (40% GC × 32 °C), T₃ (50% GC × Amb), T₄ (50% GC × 32 °C), T₅ (58% GC × Amb) and T₆ (58% GC × 32 °C). The blood glucose level was significantly (p < 0.05) lowered in groups fed with 58% GC level. Neither dietary GC levels nor temperature had a significant (p > 0.05) effect on serum cortisol and superoxide dismutase activity. Lysozyme activity was significantly higher (p < 0.05) in T₁ during pre‐ and post‐challenge period while temperature alone had a significant (p < 0.05) effect on post‐challenge Nitroblue Tetrazolium and found higher at 32 °C. A significant effect of GC levels and rearing temperature was recorded on WBC in the pre‐ and post‐challenge period. Highest pre‐challenge WBC was observed in T₄ group and in the post‐challenge period T₁ group recorded maximum. Water temperature had significant effect on pre‐challenge haemoglobin content, highest being at 32 °C (T₂). A significant (p < 0.05) effect of rearing temperature and dietary GC level on total serum protein and albumin was also observed. Highest total serum protein and albumin was recorded in T₁ and globulin in T₂. Percentage survival after challenging with Aeromonas hydrophila was highest in T₁ followed by T₃ group and lowest in T₆. The results obtained in the present study suggest that L. rohita fingerlings may utilize higher levels of dietary GC at higher temperature (32 °C) but may affect its immunity status.     

Pharmacokinetics and tissue residues of moroxydine hydrochloride in gibel carp,Carassius gibelio after oral administration

The pharmacokinetics and tissue residues of moroxydine hydrochloride were studied in gibel carp at water temperature of 15 and 25 °C. Samples (blood, skin, muscle, liver, and kidney) were collected over 10 days after the treatment and analyzed by high‐performance liquid chromatography with an ultraviolet detector. The results indicated that the influence of water temperature on the metabolism of the drug was significant. The plasma concentration–time data of moroxydine hydrochloride conformed to single‐compartment open model at the two water temperatures. There were higher absorption rate (t_1/2ka) and longer elimination half‐lives (t_1/2ke) at 15 °C (4.29 and 15.87 h, respectively) compared with those at 25 °C (3.02 and 4.22 h, respectively). The maximum plasma concentration (C_max) and the time‐point of maximum plasma concentration (T_p) were 2.98 μg/mL and 10.35 h at 15 °C and 3.12 μg/mL and 4.03 h at 25 °C, respectively. The distribution volume (V_d/F) of moroxydine hydrochloride was estimated to be 4.55 L/kg at 15 °C and 2.89 L/kg at 25 °C. The total body clearance (CL_b) of moroxydine hydrochloride was determined to be 0.25 and 0.49 L/(h·kg) at 15 °C and 25 °C, respectively; the areas under the concentration–time curve were 75.89 μg·h/mL at 15 °C and 42.33 μg·h/mL at 25 °C. The depletion of moroxydine hydrochloride in gibel carp was slower with a longer half‐life period, especially at lower water temperature that was tested.     

Would behavioral thermoregulation enable pregnant viviparous tropical lizards to cope with a warmer world?

Sceloporus lizards depend on external heat to achieve their preferred temperature (T_sel) for performing physiological processes. Evidence both in the field and laboratory indicates that pregnant females of this Genus select body temperatures (T_b) lower than 34 °C as higher temperatures may be lethal to embryos. Therefore, thermoregulation is crucial for successful embryo development. Given the increase in global air temperature, it is expected that the first compensatory response of species that inhabit tropical climates will be behavioral thermoregulation. We tested whether viviparous Sceloporus formosus group lizards in the wild exhibited differences in thermoregulatory behavior to achieve the known T_sel for developing embryos regardless of local thermal conditions. We quantified field active body temperature, thermoregulatory behavior mechanisms (time of sighting, microhabitat used and basking time) and available microhabitat thermal conditions (i.e. operative temperature) for 10 lizard species during gestation, distributed along an altitudinal gradient. We applied both conventional and phylogenic analyses to explore whether T_b or behavioral thermoregulation could be regulated in response to different thermal conditions. These species showed no significant differences in field T_b during gestation regardless of local thermal conditions. In contrast, they exhibited significant differences in their behavioral thermoregulation associated with local environmental conditions. Based on these observations, the differences in thermoregulatory behavior identified are interpreted as compensatory adjustments to local thermal conditions. We conclude that these species may deal with higher temperatures predicted for the tropics by modulating their thermoregulatory behavior.     

Influence of environmental temperature on experimental infection of redfin perch (Perca fluviatilis) and rainbow trout (Oncorhynchus mykiss) with epizootic haematopoietic necrosis virus, an Australian iridovirus

SUMMARY Experimental transmission of epizootic haematopoietic necrosis virus (EHNV) to adult redfin perch Perca fluviatilis and juvenile rainbow trout Oncorhynchus mykiss was undertaken at different water temperatures using intraperitoneal (IP) and bath inoculation. Redfin perch were highly susceptible to EHNV by both routes of infection. Bath inoculation with as few as 0.08 TCID₅₀. _mL^-1 was lethal. The incubation period in redfin perch was about 11 days at a water temperature of 19–21°C but was longer at colder temperatures and disease did not occur at temperatures below 12°C. The longest incubation period recorded in redfin perch was 28 days. Rainbow trout were not susceptible to infection by bath inoculation but the disease was reproduced after IP inoculation with 10^5.6 TCID₅₀ at water temperatures ranging from 8–21°C. The incubation period was 3–10 days at 19–21°C, but was up to 32 days at 8–10°C. Persistent infection with EHNV was detected by virus isolation in a clinically unaffected rainbow trout after 63 days. The implications of these findings in the understanding of the epidemiology of EHNV infection are discussed.     

Temperature determines the shift of thermal neutral zone and influences thermogenic capacity in striped hamsters

The thermoneutral zone (TNZ) reflects the adaptation of mammals to their natural habitat. However, it remains unclear how TNZ shifts in response to variations in ambient temperature. To test the hypothesis that ambient temperature plays a key role in determining TNZ variations between seasons, we measured metabolic rate, body temperature, and cytochrome c oxidase (COX) activity of several visceral organs in striped hamsters (Cricetulus barabensis) either acclimated to semi-natural conditions over a year, or subjected to a gradual decrease in mean temperature from 30 ± 1°C to −15 ± 1°C. The TNZ range in striped hamsters differed seasonally, with a wider TNZ and a lower lower-critical temperature in winter compared to summer. The hamsters showed a considerable leftward shift of lower-critical temperature from 30°C to 20°C after the ambient temperature of acclimation from 30°C down to −15°C, whereas the upper-critical temperature of TNZ remained fixed at 32.5°C. The resting metabolic rate in thermoneutral zone (RMRt), nonshivering thermogenesis (NST), and COX activity of brown adipose tissue, liver, skeletal muscle, brain, and kidneys, increased significantly in hamsters acclimated at lower ambient temperatures. Following acute exposure to 5°C and −15°C, hamsters acclimated to 32.5°C had significantly lower maximal NST and lower serum thyroid tri-iodothyronine (T₃) levels compared to those kept at 23°C. These findings suggest that acclimation to the upper-critical temperature of TNZ impairs the hamsters’ thermogenic capacity to cope with extreme cold temperature. Reduced ambient temperature was mainly responsible for the leftward shift of TNZ in striped hamsters, which reflects the adaptation to cold environments.     

Heat production studies on normal and oil-covered jackass penguins (Spheniscus demersus) in air and water

Heat productiorf and the importance of intact feathers for insulation were studied in jackass penguins Spheniscus demersus at various temperatures (5-25°C) by comparing their oxygen consumption in air and water with that of birds whose feather insulation was impaired when they were accidentally covered in partially weathered crude oil. Special attention was given to employing an experimental procedure that could relate oxygen consumption to level of activity. The mean ± SD metabolic rate recorded for normal inactive birds (188 ± 24 kJ kg-1 day-¹) was the same in air and water but only 80% of the mass specific rates predicted for non-passerine birds. Wetting a bird increased the inactive rate in air 1,33 times while slow swimming in water above 10°C caused a 1,76-fold increase. At low air temperatures (5°C) postural changes and feather fluffing were associated with a very low rate of 122 ± 29 kJ kg-¹ day-¹, which we interpret as behavioural control of penguins over energy expenditure. Jackass penguins in sea water at 10°C and above were within their thermal neutral range thus indicating that the water phase of their life cycle is not energetically more expensive than the terrestrial phase. Activity c level of the birds was an important influence on oxygen consumption; we suggest it is the main reason for the variations in metabolic rates within closely related species "? reported in the literature.     

Pharmacokinetics of sulphadimidine in carp (Cyprinus carpio L.) and rainbow trout (Salmo gairdneri Richardson) acclimated at two different temperature levels

Summary

The influence of temperature (10° C and 20° C) on pharmacokinetics and metabolism of sulphadimidine (SDM) in carp and trout was studied.

At 20° C a significantly lower level of distribution (Vd_area ) and a significantly shorter elimination half‐life (T _(½>) β) was achieved in both species compared to the 10° C level. In carp the body clearance parameter (Cl_B (SDM) was significantly higher at 20° C compared to the value at 10° C, whereas for trout this parameter was in the same order of magnitude for both temperatures.

N₄‐acetylsulphadimidine (N₄‐SDM) was the main metabolite of SDM in both species at the two temperature levels. The relative N₄‐SDM plasma percentage in carp was significantly higher at 20° C than at 10° C, whereas there was in trout no significant difference.

In neither species was the peak plasma concentration of N_4‐SDM (C_maxN4‐SDM)) significantly different at two temperatures.

The corresponding peak time of this metabolite (T_{max (N4‐SDM)}) was significantly shorter at 20° C compared to 10° C in both carp and trout.

In carp at both temperatures, acetylation occurs to a greater extent than hydroxylation. Only the 6‐hydroxymethyl‐metabolite (SCH₂OH) was detected in carp, at a significant different level at the two temperatures. Concentrations of hydroxy metabolites in trout were at the detection level of the HPLC‐method (0.02‐μg/ml). The glucuronide metabolite (SOH‐gluc.) was not detected in either species at the two temperatures.     

Metabolic rate and body temperature of an African sunbird,Nectarinia Chalybea: daily rhythm and the effect of ambient temperature

The oxygen consumption (VO₂) of the lesser double-collared sunbird, Nectarinia chalybea. was measured at ambient temperatures (Ta) from 7 to 35°C. The diel variation in body temperature (Tb) and wet thermal conductance (C) was also determined. The sunbirds (mean mass 8,36 g ± S.E. 0.21 g) showed a pronounced diel cycle of VO₂, with a mean reduction of 50% at night. Basal metabolic rate was estimated to be 3.23 ml O₂/g.h, which is 88% of the predicted value for a passerine bird of this size. There was a mean reduction in Tb of 3.6°C at night. Both day and night values of Tb decreased with decreasing Ta, as did individual values of C. Winter breeding in the south-west Cape is energetically stressful for lesser double-collared sunbirds, but they have the physiological capacity to reduce their energy expenditure substantially at night.     

Rectal temperature as an indicator for heat tolerance in chickens

High environmental temperature is perhaps the most important inhibiting factor to poultry production in hot regions. The objective of this study was to test adaptive responses of chickens to high ambient temperatures and identify suitable indicators for selection of heat‐tolerant individuals. Full‐sib or half‐sib Anak‐40 pullets (n = 55) with similar body weights were raised in a room with a temperature ranging from 24°C to 28°C, and relative humidity of 50% from 61 to 65 days of age. On day 66, the ambient temperature was increased within 60 min to 35 ± 1°C which was defined as the initial of heat stress (0 h). Rectal temperature (RT) was measured on each pullet at 0, 6, 18, 30, 42, 54 and 66 h. After 66 h the ambient temperature was increased within 30 min to 41 ± 1°C and survival time (HSST) as well as lethal rectal temperatures (LRT) were recorded for each individual. The gap between the RT and initial RT was calculated as ΔTn (ΔT6, ΔT18, ΔT30, ΔT42, ΔT54 and ΔT66), and the interval between LRT and initial RT as ΔTT, respectively. A negative correlation was found between HSST and ΔTn as well as ΔTT (r_ΔT18 = ?0.28 and r_ΔTT = ?0.31, respectively, P < 0.05; r_ΔT30 = ?0.36, r_ΔT42 = ?0.38, r_ΔT54 = ?0.56, P < 0.01). Importantly, pullets with low ΔT18 showed a longer HSST (256.0 ± 208.4 min) than those with high ΔT18 (HSST = 123.7 ± 78.3 min). This observation suggested that the ΔT18 or early increment of RT under heat stress might be considered as a reliable indicator for evaluation of heat resistance in chickens.     

Ultrastructural Alterations in the Gills of Labeo rohita Fingerlings Exposed to Thermal Extremes

This study aimed to determine the cellular alterations in the gill of Labeo rohita exposed to lethal temperature maxima (LT_Max) and lethal temperature minima (LT_Min) by means of transmission electron microscopy (TEM). Acclimation of advanced fingerlings of L. rohita was carried out at 26°C for 30 days. Acclimated fish were subjected to a constant rate of increase or decrease in temperature (0.3°C/min) until the LT_Max and LT_Min values were reached. Dissected gills were processed for TEM, both at the end of acclimation period at ambient temperature (26°C) and at lethal temperatures. Results indicated that at ambient temperature, the gill tissues appeared normal. However, significant changes were observed at lethal temperatures. The gill tissues at lethal temperature maxima showed severely damaged lamellae, with more vacuolated space. At lethal temperature minima, gill tissues showed increased density of mitochondria. Our prima‐facie report indicated that L. rohita exposed to lethal temperatures exhibited marked ultrastructural changes in the gills.     

Pharmacokinetics of florfenicol in blunt‐snout bream (Megalobrama amblycephala) at two water temperatures with single‐dose oral administration

The pharmacokinetics and residue elimination of florfenicol (FFC) and its metabolite florfenicol amine (FFA) were studied in healthy blunt‐snout bream (Megalobrama amblycephala, 50 ± 10 g). The study was conducted with a single‐dose (25 mg/kg) oral administration at a water temperature of 18 or 28°C, while in the residue elimination study, fish were administered at 25 mg/kg daily for three consecutive days by oral gavage to determine the withdrawal period (WDT) at 28°C. The FFC and FFA levels in plasma and tissues (liver, kidneys and muscle) were analysed using high‐performance liquid chromatography (HPLC). A no‐compartment model was used to analyse the concentration versus time data of M. amblycephala. In the two groups at 18 and 28°C, the maximum plasma concentration (C_max) of FFC was 5.89 and 6.21 μg/ml, while the time to reach C_max (T_max) was 5.97 and 2.84 hr, respectively. These suggested that higher temperature absorbed more drug and more quickly at M. amblycephala. And the elimination half‐life (T_1/2kβ) of FFC was calculated as 26.75 and 16.14 hr, while the total body clearance (CL) was 0.09 and 0.15 L kg^?1 hr^?1, and the areas under the concentration–time curves (AUCs) were 265.87 and 163.31 μg hr/ml, respectively. The difference demonstrated that the elimination rate of FFC in M. amblycephala at 28°C was more quickly than that at 18°C. The results of FFA showed the same trend in tissues of M. amblycephala. After multiple oral doses (25 mg/kg daily for 3 days), the k (eliminate rate constant) of FFA in M. amblycephala muscle was 0.017, the C₀ (initial concentration) was 3.07 mg/kg, and the WDT was 10 days (water temperature 28°C).     

A comparison of auricular, rectal and pulmonary artery thermometry in dogs with anesthesia-induced hypothermia

Objective: To determine if a correlation exists among auricular, rectal and pulmonary artery (PA) temperatures in hypothermic dogs. Design: Prospective study. Setting: Angiography suite at a college of veterinary medicine. Animals: Sexually intact female research hounds (13.9–25.4 kg; n=8). Measurements and main results: Dogs were anesthetized for instrumentation with a percutaneously placed, thermistor‐tipped, PA catheter. Anesthesia was maintained until the core body temperature decreased to 36.6°C (97.8°F). Anesthesia was discontinued, and auricular and rectal temperatures were obtained every 15 minutes until the PA temperature reached 38.3°C (100.9°F). A strong correlation was noted among the 3 methods of temperature measurement (P<0.001; R≥0.846). No statistical difference was detected among measurement methods at baseline, the minimum temperature attained, nor the median temperature attained. However, at the maximum temperature attained, auricular measurements (37.7±0.4°C or 99.8±0.7°F) were lower than either the rectal (38.3±0.3°C or 100.9±0.5°F) or PA (38.3±0.3°C or 100.9±0.5°F) temperature measurements (P=0.001). Conclusion: There is a strong correlation among rectal, auricular and PA temperatures. Auricular temperature may be used to monitor core body temperature during postoperative rewarming; however, it might be slightly lower than core temperature as normothermia is reached.     

Relationships between the addition rates of cellulase or glucose and silage fermentation at different temperatures

The influence of the application rates of cellulase preparation and glucose on silage fermentation at different temperatures was studied with the straw of naked barley (Hordeum vulgare L. emand Lam) and guineagrass (Panicum maximum Jacq.). Addition rate of cellulase and glucose, temperature and their interaction had significant effects on pH value, lactic acid content, butyric acid content and propionic acid content of naked barley straw silage and significant effects on all the parameters of guineagrass silage (P < 0.01). Temperature and interaction had significant effect on acetic acid content (P < 0.05) and no significant effect on NH₃‐N content of naked barley straw silage (P > 0.05). Under all the temperatures, the pH values of barley straw and guineagrass silages were reduced by cellulase and glucose addition even at the lowest rate (P < 0.05), compared with their corresponding control. Lactic acid contents of silages were the highest within the same temperature and same additive when glucose and cellulase were added at the highest rates, whereas the effect of cellulase and glucose addition on butyric acid production varied with their application rates and silage storage temperature. The addition rate of restricting butyric acid fermentation was lower at 20°C than that at 30°C, and it was the lowest at 40°C where cellulase and glucose addition restricted butyric acid fermentation even at 0.1 g/kg and 10 g/kg, respectively, when compared to the control. While the addition rate was lower than the above level, cellulase and glucose addition also promoted butyric acid fermentation.     

The effects of wilting and storage temperatures on the fermentation quality and aerobic stability of stylo silage

In order to clarify the ensiling characteristics of stylo (Stylosanthes guianensis Swartz), the effects of wilting (no wilting, light wilting and heavy wilting) and storage temperatures (10°C, 20°C, 30°C and 40°C) on the fermentation quality and aerobic stability of stylo silage were investigated. Wilting had no significant influence on the contents of crude protein, ether extract and acid detergent fiber, and numbers of lactic acid bacteria, aerobic bacteria, yeasts and mold (P > 0.05). Heavy wilted material, wilted for 12 h, had higher neutral detergent fiber content and lower water‐soluble carbohydrate content than unwilted and light wilted materials (P < 0.05). Wilting and storage temperatures had significant effects on pH value, acetic acid, butyric acid and NH₃‐N contents of stylo silage (P < 0.01 or P < 0.05). Wilting tended to reduce acetic acid and NH₃‐N contents and improve the fermentation quality of stylo silage. In all the silages, no wilting silage ensiled at 30°C had the highest butyric acid content (P < 0.05). High temperature of 40°C markedly restricted the growth of lactic acid bacteria and aerobic bacteria in silage, irrespective of wilting. The wilted silage or silage stored at low temperature had poor aerobic stability.