低温对羊草和牧冰草种子萌发率的影响

在25℃、5℃、-4℃和-18℃温度条件下，对根茎禾草羊草和牧冰草种子分别处理一周和两周，并置于玻璃培养皿和土壤盘中进行发芽检测，结果表明：3种低温处理的种子萌发率均有显著提高#羊草种子在处理温度为5℃、-4℃和-18℃时，萌发率基本一致，显著高于25℃处理#牧冰草种子随着处理温度的降低，萌发率显著提高，以-18℃处理效果最好；7d的低温处理效果显著高于14d；在室温、16h光照和8h黑暗条件下，土培的种子萌发率极显著高于置于玻璃培养皿的种子萌发率。     

人工低温冷藏处理解除一化性柞蚕越年蛹滞育试验初报

采用人工低温冷藏处理一化性柞蚕越年蛹 ,具有解除其滞育的效果。在温度为 0℃下冷藏处理一化性柞蚕越年蛹 8d、6 d、4d和在温度为 - 1 8℃下冷藏处理 4d,其解除一化性柞蚕越年蛹滞育的效果与出蛾集中程度、制种成绩等均优于现行的感光处理解除滞育的方法。出蛾的实际时间较感光处理解除滞育法推迟了 3 d以上     

碱茅种子发芽检测标准方法的研究

于2008年以碱茅(Puccinellia distans Parl)种子为材料,研究在10-25℃、10-30℃、15-25℃、15-30℃、20-30℃变温处理和15℃、20℃、25℃、30℃恒温以及预处理条件下,筛选确定碱茅种子发芽的最适温度和光照条件条件,为碱茅种子质量检测的标准化提供参考依据。结果表明:碱茅种子在20-30℃ 8h高温光照16h低温黑暗条件下发芽率最高,预处理对碱茅种子发芽无显著影响。碱茅种子发芽计数时间确定为第7d进行初次计数,第14d进行末次计数。并在此温度条件下选用5个碱茅种子样品进行发芽测定,可以反映碱茅种子的发芽水平,而且硝酸钾和预先冷冻处理对碱茅种子发芽促进作用不明显。     

玉树蝠蛾幼虫抗寒能力的研究

本文报道了青海冬虫夏草的优势寄主—玉树蝠蛾(Hepialus yushuensis Chu et Wang)幼虫抗寒能力。其2-4龄虫的过冷却点分别为(-19.08±1.47)℃、(-19.22±1.16)℃和(-18.43±1.05)℃。随着处理温度的降低和处理时间的延长,幼虫的存活率降低。2-4龄幼虫在-10℃下的半致死时间(Ltime50)分别为61.69d、64.68d和35.94d,低温处理2h后半致死温度(Ltemp50)分别为-14.34℃、-15.18℃和-14.12℃,高于其过冷却点。越冬幼虫在-0.2℃~-6.8℃的土壤温度中,半年也不会死亡。越冬初期幼虫体内的脂肪、糖含量升高、水分下降有利于提高其抗寒能力。幼虫经过低温适应锻炼能够显著提高其耐寒能力。     

饲喂方式和饲养温度对断奶仔猪生长性能的影响

试验采用2×2因子设计研究不同的畜舍饲养环境温度和饲喂方式对断奶仔猪生长性能和腹泻率的影响。选用21日龄杜×长×大断奶仔猪240头,随机分配到4个处理组,每个处理6个重复,每个重复10头猪。畜舍饲养温度处理的2个水平分别为28~30℃高温组和23~25℃低温组;饲喂方式处理的2个水平分别为自由采食组和定时饲喂组。结果表明:高温组(28~30℃)仔猪的平均日增重(ADG)、平均日采食量(ADFI)和饲料增重比都极显著高于低温组(23~25℃)(P<0.01)。高温组的腹泻率显著低于低温组(P<0.05)。无论在高温还是低温饲养条件下,定时饲喂组与自由采食组相比仔猪的ADG、ADFI、FCR和腹泻率都无显著差异;饲养温度和饲喂方式之间无互作效应。     

低温胁迫对返青期苜蓿叶片荧光参数的影响

为了揭示春季低温对返青期苜蓿叶片光抑制的影响,采用人工控温的方法,以苜蓿适宜生长温度(25℃)为对照,研究了返青期苜蓿叶片在-5℃处理4h、-5℃处理12h、-6.5℃处理8h和-8℃处理4h条件下叶绿素荧光参数的变化。结果表明:苜蓿叶片的叶绿素荧光参数值在25℃和-5℃处理4h、-5℃处理12h条件下差异不显著,无明显光抑制发生;但在-6.5℃处理8h和-8℃处理4h条件下,叶绿素荧光参数Fm、Fv/Fm、Fv/Fo和对照相比都明显下降,且温度越低各叶绿素荧光参数值的变化幅度越大。由此表明:低温下苜蓿叶片不同程度发生光抑制,且苜蓿各荧光参数的变化与抗寒性密切相关。     

中国野桑蚕人工饲料育研究初报

为解决野桑蚕作为试验昆虫在室内饲养难的问题,以江苏启东野桑蚕为材料,用家蚕低成本饲料进行了饲育研究。在催青期温度25℃、饲育温度27~25℃以及光照条件1~2龄12 L 12 D、3~5龄15 L 9 D的条件下,野桑蚕人工饲料育的2龄起蚕率为31.3%,幼虫期20~48 d,雌、雄蛹体质量分别为0.45、0.25 g,蛹期17~23 d,雌蛾平均产卵266粒,产滞育卵的母蛾占45.0%。研究结果表明,人工饲料育能够使野桑蚕顺利完成世代发育。     

新引1号东方山羊豆的选育与利用

1999年1月和12月分别从哈萨克斯坦和俄罗斯引入东方山羊豆种质,1999～2004年的试验研究结果表明:新引1号东方山羊豆干草产量达1 5525.8kg/hm2,初花期粗蛋白质含量23.88%,氨基酸含量14.17%.种子产量225.1kg/hm2;鲜、干草各类家畜均喜食,分枝期和初花期单宁含量分别为0.02%和0.93%.反刍家畜青饲不会发生臌胀病;种子粒径10～12目.批量种子如混杂菟丝子种子(粒径14～16目)易清选;在积雪覆盖地区-25～-45℃低温下可安全越冬,抗病虫害能力强,适宜在我国干旱、半干旱地区推广种植.     

低温对羊草和牧冰草种子萌发率的影响

在25℃、5℃、4℃和18℃温度条件下,对根茎禾草羊草和牧冰草种子分别处理一周和两周,并置于玻璃培养皿和土壤盘中进行发芽检测,结果表明:3种低温处理的种子萌发率均有显著提高;羊草种子在处理温度为5℃、4℃和18℃时, 萌发率基本一致,显著高于25℃处理;牧冰草种子随着处理温度的降低,萌发率显著提高,以18℃处理效果最好;7d的低温处理效果显著高于14d;在室温、16h光照和8h黑暗条件下,土培的种子萌发率极显著高于置于玻璃培养皿的种子萌发率。     

上海地区短低温早熟甜樱桃品种栽培初报

‘罗亚明’（Royal Minnie）和‘罗亚理’（Royal Lee）分是美国加州选育的两个短低温甜樱桃品种，两者的需冷量为200～400 h。为探索甜樱桃短低温品种在上海地区的栽培潜力，本研究发现，这两个品种在上海地区开花结果时间较早，三月中旬即进入初花期，三月下旬进入终花期，五月初果实成熟。在乔化砧木和矮化砧木上均能正常结果。两者果实中等大小，单果重8g以上,果实的形状为扁心形，果皮呈鲜红色，成熟后期为暗红色，果实硬度极高，果皮具有亮光泽，果肉红色，较紧实，果实可溶性固形物含量在20%以上，不易裂果，耐贮藏。     

Influence of high ambient temperatures on performance of multiparous lactating sows.

Multiparous Large White sows (n = 63) were used to investigate the effects of five ambient temperatures (18, 22, 25, 27, and 29 degrees C) and two dietary protein contents on their lactation performance. At each temperature treatment, ambient temperature was maintained constant over the 21-d lactation period. Dietary protein content was either 14 or 17% with essential amino acids levels calculated not to be limiting. The animals had ad libitum access to feed between the seventh and the 19th day of lactation. Diet composition did not influence lactation performance. Over the 21-d lactation, feed intake decreased from 5.67 to 3.08 kg/d between 18 and 29 degrees C. Between d 7 and 19, the corresponding values were 7.16 and 3.48 kg/d, respectively. This decrease was curvilinear; an equation to predict voluntary feed intake (VFI) from temperature (T, degrees C) and body weight (BW, kg) is proposed: VFI = -49,052 + 1,213 T - 31.5 T2 + 330 BW - .61 BW2 (residual standard deviation: 1,018). Skin temperature increased regularly with increased ambient temperature (34.6 to 37.4 degrees C between 18 and 29 degrees C), whereas udder temperature reached a plateau at 25 degrees C (38.3 degrees C). The gradient of temperature between skin and rectum was minimal (2 degrees C ) at 27 degrees C and remained constant at 29 degrees C. This constancy coincides with the marked reduction of feed intake. The respiratory rate increased from 26 to 124 breaths/min between 18 and 29 degrees C, and this indicates that the evaporative critical temperature was below 22 degrees C. The BW loss increased from 23 to 35 kg between 18 and 29 degrees C, but its estimated chemical composition remained constant. Pig growth rate was almost constant between 18 and 25 degrees C (241 g/d) and was reduced above 25 degrees C (212 and 189 g/d at 27 and 29 degrees C, respectively). In conclusion, temperatures above 25 degrees C seem to be critical for lactating sows in order to maintain their performance.     

Effect of Temperature and Dissolved Oxygen Concentration on Edwardsiella ictaluri in Experimentally Infected Channel Catfish

Abstract

Channel catfish Ictalurus punctatus were experimentally infected with Edwardsiella ictaluri by immersion exposure. After clinical disease ran its course for 52 d, the surviving fish were exposed to one of the following environmental regimes in troughs: 25°C with aeration, 25°C with no aeration, or variable temperature (18–23°C) with no aeration. After 29 d of exposure to the environmental regimes, various organs and tissues of the fish were assayed to determine the effects of these conditions on E. ictaluri concentrations (colony-forming units/mL of tissue sample). The concentrations of this pathogen were significantly (P < 0.05) higher in all tissues (trunk kidney, liver, head kidney, blood, spleen, gallbladder, muscle, brain, and gonad) 52 d postinfection than 29 d after exposure to any of the environmental regimes (81 d postinfection). Fish exposed to a near-normal concentration of dissolved oxygen (6.4 mg/L) and a constant temperature of 25°C had E. ictaluri concentrations that were significantly (P < 0.01) lower than those offish exposed to a low oxygen concentration (2.6 or 1.8 mg/L) and either a constant or a variable temperature.     

Effects of ambient temperature on growth performance and carcass traits of male growing White Pekin ducks

ABSTRACT

1. An experiment was conducted to investigate the effects of ambient temperature on growth performance and carcass traits in male growing Pekin ducks from 14 to 42 d of age in order to establish their optimal temperature requirements.

2. A total of 216 14 d old male White Pekin ducks were allocated randomly to six environmentally controlled chambers with ambient temperature set at 20°C, 22°C, 24°C, 26°C, 28°C, and 30°C from 14 to 42 d of age, respectively.

3. As ambient temperature increased from 20°C to 30°C, the body weight and weight gain decreased linearly or quadratically (P < 0.05) and was accompanied by linearly decreasing feed intake (P < 0.05). According to broken-line regression, the upper critical level of ambient temperature during the growing period for body weight, weight gain, and feed conversion ratio were 27.4°C, 27.4°C, and 26.0°C, respectively.

4. The weight of breast meat, leg meat, and abdominal fat decreased linearly or quadratically as ambient temperature increased and declined to a minimum when the temperature increased to 30°C (P < 0.05). The percentage of breast meat and abdominal fat showed a linear or quadratic decreasing response to increasing temperature, but leg meat percentage increased as temperature increased and reached maximum at 30°C (P < 0.05). According to broken-line regression, the upper critical ambient temperatures during the growing period for breast meat weight and percentage were 25.5°C and 25.6°C, respectively.

5. It was concluded that both growth performance and breast meat of growing ducks were sensitive to increasing ambient temperature and this should be kept below the upper critical temperature during the growing period in order to optimise growth performance and carcass traits at market age.     

Implication of metabolomic profiles to wide thermoneutral zone in Mongolian gerbils (Meriones unguiculatus)

Mongolian gerbils (Meriones unguiculatus) have evolved a wide thermoneutral zone (26.5–38.9 °C) and high upper critical temperature, and appear to have a high tolerance for heat exposure. Here, we use a metabolomic approach to measure global metabolite profiles for gerbils between lower (27 °C) and upper critical temperatures (38 °C) to investigate the role of metabolomic characterization in maintaining basal metabolic rates within a wide thermoneutral zone. We found that in serum and liver, 14 and 19 metabolites were significantly altered, respectively. In the aerobic respiration‐related tricarboxylic cycle (TCA), 5 intermediates (isocitric acid, cis‐aconitic acid, α‐ketoglutaric acid, fumaric acid and malic acid) were increased in serum in 38 °C animals; however, no such increase was found in the liver. A stable level of hepatic TCA cycle intermediates may be related to the steady state of aerobic respiration at 38 °C. Metabolomic results also revealed that acute heat exposure caused increased oxidative stress and low molecular weight antioxidants in Mongolian gerbils. Increased methionine and 2‐hydroxybutyrate suggest an accelerated synthesis of glutathione. Increased urate and its precursors, inosine and hypoxanthine, were detected at 38 °C. Glucuronate, threonate and oxalate involved in ascorbate synthesis and degradation were increased in serum at 38 °C. In conclusion, although dramatic metabolomic variation was found, a stable hepatic TCA cycle may contribute to maintaining a constant basal metabolic rate within a wide thermoneutral zone in Mongolian gerbils.     

南方地区甜樱桃不同品种及树形组合筛选

以甜樱桃主栽品种“布鲁克斯”、“红蜜”、“拉宾斯”、“萨米脱”、“黑珍珠”、“秦林”、“06-7”为试材,研究在南方山地条件下不同栽培模式对生长量、果实品质及产量的影响。结果表明：在高海拔条件下甜樱桃物候期相应推迟7-14天；不同树形树势存在显著差异,UFO树形树势良好,且对于果实品质提高有一定作用；UFO树形可显著提高“布鲁克斯”、“06-7”、“萨米脱”等品种产量。该研究为甜樱桃在浙江等南方地区推广合理树形提供参考依据     

Gut and intestinal passage time in the Rainbow Skink (Trachylepis margaritifer): implications for stress measures using faecal analysis

Stress levels in organisms provide a rapid measure for assessing population health. Handling and capture stress, however, cause error in blood measures, so this method is rapidly being replaced by assessing levels of stress metabolites in faeces. This eliminates the source of error because there is a lag period between stress perception and the resultant stress metabolite accumulation within faeces. This lag period is correlated with specific intestinal passage time, a measure that can vary greatly between taxa, particularly amongst ectotherms. Due to two deleterious consequences associated with extended exposure of the metabolites to the intestinal environment, species that exhibit long and variable intestinal passage times are not good candidates for metabolite studies. We measured gut and intestinal passage times in Trachylepis margaritifer to ascertain whether it would be an appropriate candidate for stress metabolite studies. We first tested if barium sulphate in the meal had an effect on gut passage time at three ambient temperatures (25, 27 and 32 °C). Barium sulphate had no effect; however, temperature had a significant effect with an unexpected pattern: gut passage time was fastest at 32 °C but was slower at 27 °C than at 25 °C. We then used X‐ray technology and barium sulphate‐loaded meals to measure gut and intestinal passage times at 25 and 27 °C. This allowed us to observe which parts of the digestive process were responsible for increased passage times at 27 °C: the faster passage time at 25 °C was due to faster intestinal passage time; there was no difference in gastric emptying time. We assess the species to be a suitable candidate for studies using faeces to measure stress. It is imperative however, that the effect of temperature on passage rates is known and taken into account in such studies.     

Influence of Temperature on the Arginine and Methionine Requirements of Young Broiler Chicks

Two experiments were conducted with Ross × Ross broiler chicks in battery brooders from 7 to 21 d of age to determine the Arg and Met requirements of young broiler chicks at control (25°C) and warm (35°C) temperatures. In both experiments, 1-d-old broiler chicks were fed a corn and soybean meal based starter diet for 7 d. Six replications (2 replicates in each of 3 rooms per temperature) with 8 chicks each were used for each treatment. In experiment 1, the basal diet was based on corn (34.52%), whey (26.96%), corn gluten meal (16.53%), soybean meal (11.74%), and poultry fat (23% of CP and 3.20 kcal/g of ME_n). Six levels of Arg (0, 0.1, 0.2, 0.3, 0.4, and 0.5%), supplementing the basal diet containing 0.95% Arg, were the dietary treatments. A broken-line linear model was used to estimate chick Arg requirements. Based on body gain and feed conversion ratio (FCR) data, respectively, the Arg requirements of young Ross × Ross broiler chicks raised at 35°C were 1.15 ± 0.03% and 1.13 ± 0.02%, whereas those of chicks at 25°C were 1.26 ± 0.03% and 1.27 ± 0.02%. In experiment 2, the influences of temperature and dietary Arg on the Met requirements of young broiler chicks were investigated. The basal diet was based on corn (53.45%), soybean meal (37.72%), and poultry fat (23% of CP and 3.20 kcal/g of ME). Experiment 2 had a 6 × 2 factorial arrangement, with the basal diet (0.35% Met and 1.52% Arg) supplemented with 6 levels of dietary Met (0, 0.05, 0.1, 0.15, 0.2, or 0.3%) and 2 levels of dietary Arg (0 and 1.0%). When chicks were fed a corn-soybean meal basal diet containing 1.52% Arg, the Met requirements of young Ross × Ross broiler chicks raised at 35°C were 0.43 ± 0.02% and 0.43 ± 0.03%, whereas those of chicks at 25°C was 0.43 ± 0.01% and 0.48 ± 0.03%, based on body gain and FCR data, respectively. When Arg levels were increased to 2.52%, the Met requirement of young Ross × Ross broiler chicks was greater at both temperatures (P < 0.05). The requirements of chicks raised at 35°C were 0.50 ± 0.02% and 0.49 ± 0.02% and at 25°C were 0.59 ± 0.03% and 0.57 ± 0.02%, based on body gain and FCR data, respectively. Temperature and amino acid balance may both affect the amino acid requirements of broilers.     

Yolk‐sac larval development of the substrate‐brooding cichlid Archocentrus nigrofasciatus in relation to temperature

In order to conserve and culture the cichlid fish Archocentrus nigrofasciatus, more information about its reproductive biology and its larval behavior and morphogenesis is necessary. Currently, temperatures ranging from 21 to 27 °C are used in ornamental aquaculture hatcheries. Lower temperatures are preferred to reduce the costs of water heating, and 23 °C is usually the selected temperature. However, there is limited information on culturing protocols for ornamental species and most of the information generated on this topic remains scarce. Thus, the present study examines the morphological development of Archocentrus nigrofasciatus during the yolk‐sac period up to the age of 100 h post‐hatching in relation to 2 temperature regimes used in ornamental aquaculture: a temperature of 27 °C (thermal optimum) and a decreased temperature of 23 °C (thermal tolerance). The results of this study suggest that the 27 °C temperature generates intense morphological changes in yolk‐sac development in a shorter period. This has advantages as it reduces the time of yolk‐sac larval development, and, thus, minimizes the transition phase to exogenous feeding and maximizes the efficiency at which yolk is converted into body tissues. The present paper provides necessary information to produce freshwater ornamental fish with better practices so as to increase larval survival and capitalize on time for growth.     

Influence of temperature on the reproduction of the earthworm Eisenia foetida (Oligochaeta)

An experimental investigation revealed that cocoon production by E. foetida (Oligochaeta) increased linearly with increase in temperature in the range 10 to 25 °C. Diurnally fluctuating temperature did not have a marked influence on total cocoon production at the temperature levels of 10, 15 and 25 °C. A highly significant difference in cocoon production occurred between a constant temperature of 20 °C and a mean temperature of 20 °C (which fluctuated diurnally between 12 and 28 °C). Maximum cocoon production was obtained at 25 °C with each worm producing a cocoon every second day. The investigation also showed that temperature does influence the number of hatchlings per cocoon. At a temperature of 25 °C fewer worms hatched per cocoon than at 20 °C.     

Apparent Metabolizable Energy Needs of Broilers from Two to Four Kilograms as Influenced by Ambient Temperature

During winter production, the optimum temperature set points for heavy broilers (>3.4 kg) approaching market weight are subject to debate in commercial practice. Apparent ME needed to optimize nutrient utilization may be influenced by ambient temperature. This experiment examined potential interactive effects of AME × ambient temperature from 36 to 60 d of age. A 4 × 2 factorial arrangement of treatments was used. Dietary treatments were diets formulated to 3,175, 3,220, 3,265, and 3,310 kcal of AME/kg. Two temperature regimens were provided consisting of variable temperature regimen (VTR) or constant temperature regimen (CTR) set points. The VRT was 21.1°C from 36 to 38 d of age, 20.2°C from 39 to 42 d of age, 18.9°C from 43 to 46 d of age, 17.8°C from 47 to 50 d of age, 15.6°C from 51 to 54 d of age, and 12.8°C from 55 to 60 d of age. The CTR was 21.1°C from 36 to 60 d of age. Significant AME × temperature interactions were observed for cumulative BW, BW gain, feed consumption, feed conversion, and mortality. In the CTR, increasing AME led to increased BW gain but not in the VTR. As dietary AME increased, the improvement in feed conversion was more pronounced in the CTR than the VTR. With the VTR, decreasing AME increased feed consumption. The experimental treatments did not influence abdominal fat percentage or total breast meat yield. These data provide evidence that broilers exposed to CTR respond to increased AME.