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991.
用灌胃法给予小鼠安定2.5、12.5、25.0mg/kg后,在热应激(45±1℃)和冷应激(-5±1℃)条件下,给予安定2.5 mg/kg的给药应激组小鼠的存活时间与应激对照组无差别;而12.5、25.0 mg/kg的给药应激组的存活时间与应激对照组比较,热应激小鼠存活时间延长,而冷应激小鼠的存活时间缩短。安定(12.5 mg/kg)可明显抑制热(38±1℃)应激10min和冷(-5±1℃)应激5min条件下小鼠血浆皮质酮的升高,而当热应激(38±1℃)时间延长至60min,冷应激(-5±1℃)延长至30min时,安定对应激导致的小鼠血浆皮质酮升高则无作用。安定(12.5mg/kg)对热(38±1℃)应激60min引起的小鼠皮质醛固酮、甲状腺素T_4的变化也无明显影响。在热(38±1℃)应激30min的条件下,肌肉注射安定10mg/kg的给药应激组大鼠,血清肌酐,脲氮、谷草转氨酶(SGOT)、谷丙转氨酶(SGPT)明显升高,而应激对照组仅有血清肌酐,SGOT的升高。总之,安定对动物抗环境热和冷应激能力无明显影响。 相似文献
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从已分离的多个狗牙根(Cynodon dactylon)内生固氮菌株中筛选到两株固氮酶活性较高的菌株7D和BM13,为明确固氮菌株对环境因子的适应性,研究了在不同的生长环境条件下菌株的生长量。采用Ashby无氮培养基,测定了温度、pH、渗透压以及不同氮源和碳源等环境条件对固氮菌生长的影响。结果表明,在10~40℃的温度范围内、pH值3.92~9.64的酸碱环境和30g·L~(-1) NaCl的高渗透压下,固氮菌7D和BM13均能正常生长;菌株能耐受0~10mmol·L~(-1)的NH_4~+和NO_3~-,而且能利用蔗糖、甘油、麦芽糖、甘露醇和葡萄糖等多种碳源生长。说明狗牙根内生固氮菌株7D和BM13对环境因子有很强的抗逆性和适应性,但两菌株之间存在一定差异,可望进一步研发成为优良的固氮微生物肥料生产菌种。 相似文献
997.
YU Zu-hua DING Ke HOU Kui LI Yuan-xiao LI Wang LIU Yi-chen CAO Ping-hua JIA Yan-yan CHENG Xiang-chao 《中国畜牧兽医》2016,43(4):1006-1011
In order to improve the ability of producing cellulase of Bacillus lichenniformis, the mutational strain was screened after Bacillus lichenniformis LY02 was induced by UV.Then the best optimal enzyme-producing condition, inoculum size, temperature, incubation time, initial pH and metal ions were studied.The results showed that the cellulase activity of mutated strain was increased by 34.31%.And the best optimal ferment conditions were as follows:Inoculation concentration was 1.5%, cultivated temperature was 37℃, ferment time was 24 h, initial pH of medium was 5.0, and K+ and Ba2+ could promote the cellulase producing.These results were contributed to develop the strain to be applied in practice. 相似文献
998.
Effect of body condition score and reuse of progesterone‐releasing intravaginal devices on conception rate following timed artificial insemination in Nelore cows 下载免费PDF全文
LL Pereira AP Ferreira WG Vale LR Serique KAL Neves AC Morini BM Monteiro AHH Minervino 《Reproduction in domestic animals》2018,53(3):624-628
This study had the aim of investigating the efficiency of timed artificial insemination (TAI) through the progesterone‐releasing intravaginal device (PRID), used in new condition and for the second and third times in Nelore cows. The effects of device reuse and body condition score (BCS) on the conception rate (CR) were evaluated in 1,122 multiparous Nelore cows (mean BCS of 2.7 ± 0.4), which were randomly distributed into three groups that received new (n = 330), once (n = 439) and twice used (n = 353) PRID. Among the 1,122 females that underwent TAI, 573 became pregnant, thus representing an overall CR of 51.06%. Cows with BCS between 2.75 and 4.0 had greater (p < .0001) CR (69.75%) than cows with BSC of 2.0–2.5 (32.98%). It was observed that the CR through using PRID was 60.00%, 51.71% and 41.93% for new, once and twice used PRID, respectively, with difference between all groups (p < .0001). Under tropical conditions, animals with BCS greater than 2.5 had a higher CR, and the CR decreased proportionally with the number of times that the PRID had been used. 相似文献
999.
As the primary land use in the Karoo, extensive small-stock farming contributes significantly towards the agricultural economy of the region. However, the sustainability of this practice has been questioned for many years. This led to the establishment of a long-term stocking-density trial in 1988 at the Carnarvon Research Station. The trial was designed on a three-camp rotational grazing system under four stocking densities (8, 7, 5.5 and 4 ha SSU–1). Following continuous treatment over 28 years, the results from a once-off assessment in February 2016 portrayed no significant differences between treatments with regard to plant height, cover, species diversity, ecological and grazing index scores. Animal production varied among treatments where the mean production per hectare was found to be the highest under the high stocking-density treatment. Due to the absence of historical data, the results from this study are not conclusive with regards to changes in the vegetation dynamics over time and therefore does not lend itself to making conclusions concerning stocking densities. It can, however, be concluded that the vegetation of the Western Upper Karoo is remarkably resilient to the perceived higher stocking densities set at the time, on condition that an appropriate grazing management strategy is applied. 相似文献
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为研究妊娠后期营养水平对初产母猪体况、繁殖性能及血液生化指标的影响,本试验选用背膘厚及体重相近的初产杂交母猪36头,按体况和配种时间随机分为3组(Ⅰ、Ⅱ、Ⅲ组),每组6个重复,每个重复2头母猪,饲喂营养水平依次为维持需要的1.5、2.0和2.5倍的日粮,母猪妊娠81 d时开始试验至母猪分娩结束,试验期33 d。结果显示,分娩时Ⅰ组母猪背膘厚显著低于Ⅲ组(P<0.05),断奶时各组背膘厚度差异不显著(P>0.05);Ⅰ组母猪泌乳期背膘损失显著低于Ⅲ组(P<0.05);Ⅲ组母猪分娩后体重、分娩前体重均显著高于Ⅰ组(P<0.05),各组母猪妊娠81 d体重及泌乳期失重等差异均不显著(P>0.05)。试验组间窝产仔数、窝产活仔数、断奶个体重及母猪断奶-发情间隔均无显著差异(P>0.05);Ⅲ组仔猪初生均重、断奶窝重、泌乳期窝增重均显著高于Ⅰ组(P<0.05)。随营养水平升高,Ⅱ、Ⅲ组雌激素水平显著高于Ⅰ组(P<0.05);各组催乳素和孕酮水平差异不显著(P>0.05);Ⅰ组甘油三酯水平显著低于Ⅱ、Ⅲ组(P<0.05);各组尿素氮和葡萄糖含量随营养水平的升高逐渐增大,且差异显著(P<0.05);Ⅲ组胰岛素含量显著高于I组(P<0.05);各组总蛋白含量无显著差异(P>0.05)。结果提示,母猪妊娠后期饲喂营养水平为2.0倍维持需要的日粮时可使后备母猪分娩时体况达到标准水平,而饲喂营养水平为2.5倍维持需要的日粮可使母猪产仔性能得到提高。 相似文献