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试验研究了铜川地区TMR饲养方式对奶牛生产性能指标的影响,以期在奶牛生产中有一定的实践指导作用。试验将40头泌乳后期的荷斯坦牛分成2组,每组20头。结果表明,试验组日产奶量比对照组提高了2.35 kg(P0.05),乳蛋白提高了0.15%(P0.05),干物质提高了2.16%(P0.05),整个试验期奶牛健康状况良好,试验组与对照组相比,每头每日平均多增加经济收入为2.93元,TMR饲喂奶牛经济效益明显。 相似文献
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<正>高产奶牛对高温比较敏感,当夏季温度超过28℃时,奶牛就会出现明显的不良反应。高温对奶牛生理、采食量、奶质、泌乳量、繁殖性能、免疫性能等方面产生不利影响,导致产奶性能、繁殖性能和免疫能力下降,严重者可导致奶牛死亡,常常造成一定经济损失。对高温给奶牛造成的影响进行分 相似文献
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BST能够显著提高奶牛产奶量,引发了世界各地的深入广泛研究,其安全性始终是我们关注的焦点。本文就BST的作用机理、对奶牛生产的影响和安全问题三个方面进行综述。 相似文献
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The effects of feed restriction on channel catfish production, processing yield (carcass and fillet), visceral composition and body shape traits were determined. Channel catfish (initial mean weight =0.77 kg) were stocked into six 0.04‐ha ponds at ～5775 kg ha?1. Two ponds were assigned to each of three feeding regimes for a 4‐week trial: fed daily to satiation, fed once weekly to satiation and not fed. Fish were measured for weight, processing yield and visceral components after 2 and 4 weeks, and for body shape after 4 weeks. Growth was fastest in fish fed daily, intermediate in fish fed weekly and slowest in unfed fish. There were no differences in survival among feeding regimes. After covariate adjustment for weight differences, fish fed daily had shorter, thicker bodies, and smaller heads than fish from feed‐restricted treatments. Carcass yield was higher for females than males and higher at week 2 than at week 4, but was not affected by feeding regime. Fillet yield was higher for females than males, higher at week 2 than at week 4, and higher for fish fed daily than for feed‐restricted fish (fed once weekly and not fed). Viscerosomatic index (VSI), visceral fat‐somatic index (VFI) and hepatosomatic index were higher at week 2 than at week 4, and highest for fish fed daily, intermediate for fish fed weekly and lowest for unfed fish. Hepatosomatic index and VSI were higher for females than males, but VFI was not different between genders. The female gonadosomatic index increased over time but was not affected by feeding regime. Short‐term feed restriction had negative impacts on growth and fillet yield. Processors could benefit by marketing severely feed‐restricted channel catfish as carcasses rather than fillets since fillet yield declined but carcass yield was unchanged by feed restriction. 相似文献
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Three approaches for multivariate analysis of fish growth in aquaculture experiments with Nile tilapia (Oreochromis niloticus niloticus L.) based on the von Bertalanffy growth curve are presented and compared. The approaches are: an extended Gulland‐and‐Holt (GH) plot, a forced extended GH plot and a multilinear regression analysis for the growth parameter K. All three models provide valuable insight into the major environmental factors influencing the daily growth rate and explain 28–46% of the variance of the observed daily growth rate of the used data set. For all three methods, the modelled parameter is significantly related to the net yield of Nile tilapia and can, therefore, be used for the predictive modelling of management scenarios. The extended GH plot loads the influence of environmental parameters upon L∞, while the forced extended GH plot and Direct fitting of K load the influence on the growth parameter K. The latter is more in the tradition of aquaculture research. But the forced extended GH plot and Direct fitting of K can only be applied if L∞ of the cultured species is known, as the selected L∞ influences the variance in the regression variables. 相似文献
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为研究地膜光伏工程化养殖模式的实用性,在地膜光伏工程化养殖系统中开展凡纳滨对虾养殖试验。地膜光伏工程化养殖系统由对虾养殖系统和光伏发电系统组成。取3口池塘进行凡纳滨对虾高密度养殖试验,放养密度为500尾/m^2,养殖试验周期100 d。凡纳滨对虾平均体长达到(9.77±0.11)cm,平均体质量(10.80±0.82)g。1号池塘产量为4.25 kg/m^2,存活率为78.71%,饲料系数为1.22;2号池塘养殖产量为4.42 kg/m^2,存活率为81.85%,饲料系数为1.18;3号池塘产量为4.07 kg/m^2,存活率为75.37%,饲料系数为1.25。养殖期间8:00水温范围为22.5~31.0℃;15:00水温范围为22.5~32.0℃,日气温差最大为11.0℃,日水温差最大为2.5℃。养殖期间pH稳定在7.00~8.34。养殖期间亚硝酸盐氮(NO-2-N)0~8.47 mg/L,总氨氮(TAN)0~7.83 mg/L。地膜光伏工程化养殖模式养殖凡纳滨对虾,实现了对虾养殖和光伏发电的双重收益,具有较大的实用价值,是一种值得推广的养殖模式。 相似文献
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Hitoshi Kaneko Takeshi Okunishi Takashi Seto Hiroshi Kuroda Sachihiko Itoh Shinya Kouketsu Daisuke Hasegawa 《Fisheries Oceanography》2019,28(2):212-227
To clarify the effects of temperature on the recruitment of chub mackerel (Scomber japonicus) in the North Pacific, we investigated the influence of winter surface temperature (WST) on spawners at the time of maturity around the spawning grounds and the influence of ambient spring temperature on larvae using estimated temperature (ET) obtained from particle tracking experiments. We found a significant positive correlation between ET approximately 10 days following hatching and the recruitment per spawning stock biomass (RPS) after 2000. The closer (more meandering) the Kuroshio Current (KC) axis was in relation to the spawning ground, the higher (lower) the spring surface temperature and the higher (lower) RPS was in the spawning ground. In contrast, WST inside KC near the maturity/spawning ground was significantly negatively correlated with RPS. A significant negative correlation between the temperatures in winter and spring was detected in the area after 2000, when the conditions of the Pacific decadal oscillation index and the stability of the Kuroshio Extension were synchronous, indicating that KC shifted northward during this time. The reversed temperature pattern was consistent with the winter–spring movement of KC axis in the offshore direction and was correlated with the winter–spring difference in the intensity of the Aleutian low. These results suggest that the annual variation in chub mackerel recruitment after 2000 was strongly affected by the combined effects of ambient temperature because of the reversal of conditions that occurred between winter and spring around the maturity/spawning ground, which was related to the KC path. 相似文献
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响应曲面法优化麒麟菜卡拉胶碱处理工艺 总被引：1，自引：0，他引：1
采用响应曲面法研究了碱液质量浓度、浸泡时间和浸泡温度对麒麟菜（Eucheuma）卡拉胶的凝胶强度和产率的影响。在单因素试验基础上采用Box—Benhnken中心组合试验,以碱液质量浓度、浸泡时间和浸泡温度为影响因素,以凝胶强度和产率为响应值建立二次回归方程,通过响应面分析得到优化组合。结果显示,碱处理优化工艺参数为碱液质量浓度250g·L-1、浸泡时间3．5d和浸泡温度25℃,在此条件下提取的麒麟菜卡拉胶凝胶强度为721g·cm-2（质量浓度10g·L-1）,产率为35．17％。 相似文献
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Friedrich Ladich 《Fish and Fisheries》2018,19(4):598-612
Temperature affects peripheral and central mechanisms of signal production and detection in ectothermic animals. This study reviews for the first time the effects of temperature on acoustic communication in fishes and analyses whether changes in sound properties are coupled to changes in auditory sensitivities. Effects of temperature on sound production have been studied in approximately one dozen families of teleosts. Calling activity increased or was unaffected by temperature, in the latter case probably because seasonal, daily and lunar rhythms also influence mating behaviour and calling. Sound characteristics (pulse repetition rate, fundamental frequency) are positively correlated with temperature if pulses are directly based on sonic muscle contractions. In fishes possessing other sonic mechanisms, the dominant frequency of their pulsatile pectoral sounds may increase as well. Auditory sensitivities were mainly determined in otophysines, which possess enhanced hearing abilities. Studies revealed that hearing increased with temperature, in particular at higher frequencies. We know close to nothing about whether temperature‐dependent changes in sound characteristics are coupled to changes in auditory sensitivity or mate choice. Female midshipman toadfish appear to choose males based on call frequency, which varies with temperature. Future studies need to address several topics: (i) temperature effects on sound production have to be separated from other sources of variation; (ii) effects on hearing need to be studied in many more taxa; (iii) potential negative effects of global warming on acoustic communication (because of temperature coupling) need to be investigated because fish constitute a major source of protein for humans. 相似文献
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不同抗热应激添加剂对奶牛生产性能的影响 总被引：4，自引：0，他引：4
本试验研究了不同抗热应激添加剂对泌乳牛生产性能的影响,试验分4个处理,每个处理10头奶牛,A处理为对照组,喂以基础日粮,B处理在A处理组基础日粮上添加维生素C(1000～1600mg/日·头),C处理在A处理基础上添加电解质(NaHCO30.03kg/日·头,KCl0.03kg/日·头,NH4Cl0.03kg/日·头),D处理在A处理基础上添加中草药添加剂(75g/日·头)。试验结果表明,在产奶量方面,添加中草药处理组效果最好,与对照组、维生素组、电解质组差异极显著(P<0.01);其次是电解质组较好,与对照组、维生素组差异极显著(P<0.01);维生素组最差,与对照组比较,差异不显著(P>0.05);在投入产出比方面,中草药组最好,其次是电解质组。 相似文献
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随着乳业的快速发展，奶源紧张的状况无法在短期内改变，原料乳成为制约我国乳业发展的瓶颈。黑龙江省有乳业发展得天独厚的优势，散养模式仍然是黑龙江省生产原料乳的主要模式，分析奶农的生产行为具有重要意义。本文在实地调研的基础上，对黑龙江省奶农在原料乳生产过程中的行为进行研究，以期探寻奶农的生产行为对乳业发展的影响。 相似文献
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《Aquaculture (Amsterdam, Netherlands)》1987,64(3):199-207
The optimum ration in relation to water temperature has been determined for juvenile sea bass (Dicentrarchus labrax). Fish were reared at 15 and 20°C. The spontaneous food intake was positively related to temperature. Four daily rations were tested at both temperatures. The optimum rations were 1.7% at 20°C and 1.2% at 15°C for fish weighing 20–30 g. The influence of temperature on growth rate, body composition and food conversion was studied. Increasing the temperature improved growth rate and gross conversion efficiency but not gross protein efficiency. The results are discussed in terms of energy utilization. 相似文献