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An experiment was started in 1957 that compared the production from dairy cows on daily strip-folding with that from a system of rotational grazing where the cows were given a fresh allocation of pasture about once or twice a week. Management was so arranged that equal areas of pasture were grazed off by the same number of cows in a similar period of time. The experiment was carried out at two rates of stocking, one about 20% greater than the other, the lower rate considered to be equivalent to good close folding practice and the higher rate therefore somewhat restrictive. No supplementary food was given during the grazing season.
At the high rate of stocking, rotational grazing gave an average milk yield of 40 lb./cow/day whilst daily strip-folding yielded 38 lb./cow/day. At the low rate of stocking production was 42 lb./cow/day for both methods.
At the high rate milk yield/acre from the rotational grazing was 1007 and from the strip-folding 977 gals. At the low rate comparable results were 881 and 874 gals.
There was no general trend in yield per cow or per acre in favour of either the rotational grazing or daily strip-folding systems of management. Increasing cow days/acre by 21% decreased yield/cow/day by 7% but significantly increased milk yield/acre, by 13%. 相似文献
At the high rate of stocking, rotational grazing gave an average milk yield of 40 lb./cow/day whilst daily strip-folding yielded 38 lb./cow/day. At the low rate of stocking production was 42 lb./cow/day for both methods.
At the high rate milk yield/acre from the rotational grazing was 1007 and from the strip-folding 977 gals. At the low rate comparable results were 881 and 874 gals.
There was no general trend in yield per cow or per acre in favour of either the rotational grazing or daily strip-folding systems of management. Increasing cow days/acre by 21% decreased yield/cow/day by 7% but significantly increased milk yield/acre, by 13%. 相似文献
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云南昌宁大叶茶和腾冲大叶茶的染色体数目都是2n=30。15对同源染色体中,有11对m型染色体和4对sm型染色体,没有发现具随体的染色体。根据Levan等的分类体制鉴定,这2个品种的核型为2n=22m 8sm,属于Stebbirs核型分类的1A型。 相似文献
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A medium quality barn-dried hay and a poor quality field-cured hay were each supplemented with 3 levels of concentrate in the diet of young beef cattle, averaging 313 kg liveweight. The supplement was given on predetermined hay concentrate metabolizable energy (ME) ratios based on the determined ME of the hays and an assumed ME of 3·0 McalsAg DM for the supplement. The hay concentrate ratios used were 1:1, 1:2 and 1:3, the aim being to provide a reasonable rate of growth (0·7 kg/day) with the poorer hay. It was necessary to include urea in the concentrate mixtures used on the 1:1 and 1:2 ratios with the field-cured hay. The urea appeared to have an adverse effect on the intake and utilization of DM on the 1:1 ratio. The range of mean intakes of supplement DM was 3·02 to 4·41 kg/day for the barn-dried hay and 2·23 to 4·61 for the field-cured hay. Mean daily liveweight gains with the barn-dried hay were 0·76, 0·89 and 0·85 kg for the 1:1, 1:2 and 1:3 ratios, respectively, with no significant difference between ratios. The mean daily gains with the field-cured hay were 0·39, 0·77 and 0·75 for the three ratios, the mean gain on the 1:1 ratio being significantly lower than those of the other ratios. The ME conversion ratios were not significantly affected by either ratios or hay type, except on the 1:1 ratio with field-cured hay. There were significant differences between the barn-dried hay and field-cured hay diets in the digestibilities of DM, organic matter, crude protein and energy; the mean coefficients for DM being 74·5% and 65·6%, respectively. 相似文献
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Three sets of previously-published experiments have been re-analysed by numerical methods intended for the elucidation of pattern in sequential data. The results suggest that for Setaria sphacelata cv. Nandi and Chloris gayana cv. Samford Rhodes the stable terminal silage to be expected under subtropical conditions is not the high lactic-acid silage of temperate regions, but a silage with a relatively high proportion of acetic acid. Lactic-acid silage is formed, but usually behaves as though in a transitional phase. However, silage made from mature Setaria can be maintained in the lactic-acid phase by the addition of high percentages of sugar. The silage fermentation can sometimes be retarded, or deflected into an undesirable path for reasons that are not understood.
The above patterns suggest three hypotheses for more fundamental investigation. First, since acetic-acid silage can be expected under most subtropical conditions, its properties require careful investigation. Secondly, relatively young Setaria may be regarded as a source of acetic-acid silage, but the optimum amount of sugar to be added for ensiling more mature grass needs investigation. Thirdly there is an urgent need to investigate the causes of retardation of fermentation, and of its deflection into an undesirable path, because until these causes are understood, the outcome of ensilage will remain uncertain. 相似文献
The above patterns suggest three hypotheses for more fundamental investigation. First, since acetic-acid silage can be expected under most subtropical conditions, its properties require careful investigation. Secondly, relatively young Setaria may be regarded as a source of acetic-acid silage, but the optimum amount of sugar to be added for ensiling more mature grass needs investigation. Thirdly there is an urgent need to investigate the causes of retardation of fermentation, and of its deflection into an undesirable path, because until these causes are understood, the outcome of ensilage will remain uncertain. 相似文献
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本文揭示了黄淮大豆产区二个推广品种豫豆8号、中豆19各生育期器官干重、N、P、K浓度变化;中豆19对三要素的吸收速率、转运率低于豫豆8号;二品种在高产密度下比其它密度下生产1kg籽粒产量所需三要素量低。豫豆8号高产密度为1.2万株,亩产大豆299.2kg,生产1kg籽粒产量需N、P、K分别为0.1529、0.0174、0.0643kg,中豆19的高产密度为1.6万株,亩产197.8kg、形成1kg籽粒产量的需三要素分别为0.1610、0.0218、0.0967kg,明显高于豫豆8号。 相似文献
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盆栽试验结果表明，氯化钾和硫酸钾均能提高马铃薯叶绿素含量，块茎产量较对照增加显著。供试两种钾肥对马铃薯淀粉含量有增加作用，但对维生素C含量有降低趋势。田间试验结果表明，钾肥具有增加大、中薯，降低小薯比例的效果，从而提高商品率。在海伦黑土上，每公顷施氯化钾52．5～202．5kg，增产块茎6．8％～17．6％。在富锦黑粘土上，每公顷施等量的氯化钾，增产块茎6．5％～20．0％。 相似文献
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两个大豆[Glycine Max（L.）Merril]品种光合作用日变化的研究 总被引：1，自引：0，他引：1
对两个大豆品种光合作用日变化的多次测定,结果表明:两个大豆品种的光合速率(A)日变化均呈双峰曲线,气孔阻力(R_s)的日变化与A相反,但中午时的细胞间隙CO_2浓度(Ci)只有轻微的降低,这说明中午A降低的内部因素除气孔限制外,还有非气孔因素的限制。中午时的光量子通量密度(PPFD)和大气温度(Ta)升高,相对湿度(R_H)下降,引起叶片温度(Te)的升高。 相似文献
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利用８对抗－感大豆叶食性害虫近似等位基因系，１００个随机引物进行ＰＣＲ扩增，在４０６个稳定重现的片段中，有２个在近等基因系间表现多态性；不同抗性来源的两组材料间的多态性ＤＮＡ片段的有／无呈相反趋势，相同抗性来源的材料间的多态性ＤＮＡ片段的有／无也存在差异。由此可以认为，抗性供体ＰＩ１７１４５１，ＰＩ２２９３５８的抗性背景ＤＮＡ的多样性比较丰富，遗传背景相差较大，说明它们的抗性基因来源不同。在进行广 相似文献
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双T-DNA表达载体转化大豆的研究 总被引：5，自引：1，他引：4
利用含有筛选标记基因和目的基因△6-脂肪酸脱氢酶基因的双T-DNA共转化表达载体pLIN61,经农杆菌EHA101介导,采用子叶节转化法转化大豆,使用除草剂Glufosinate作为筛选剂,获得了一批携带有玻璃苣△6-脂肪酸脱氢酶基因的转基因大豆,转化效率为2.0%,共转化频率及实际转化率分别为56.25%、1.12%.PCR检测和Southern杂交结果证明,玻璃苣D6D已经整合到大豆的基因组上.RT-PCR检测结果显示,玻璃苣△6-脂肪酸脱氢酶基因在转基因大豆的转录水平上得到了表达. 相似文献
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A new simplified grazing management system has been devized for spring- or antumn-born calves scbednled for beef production at 18 months of age on a grass/cereal system. The new system which can be conveniently described as the two-field system obviates the need for paddock fencing and paddock water installations, is simple to operate and is giving results in terms of liveweight gain performance and stocking rates per acre which are comparable with those from paddock systems. The new system employs the old practice of set-stocking. Two fields are used, however, and these are alternately set-stocked and cut for silage, or vice-versa. It has been found that by using N fertilizer to the same extent as in intensive paddock systems, i.e. around 250–350 units N/ac, it has been possible to achieve similar stocking rates/ac and performance has been unimpaired. No bealth upsets have occurred as a result of applying fertilizers on fields in the presence of grazing cattle over a period of four years at two centres, Jealott's Hill and The Leaths, in trials involving hundreds of beef cattle and dairy cows. This new system of grazing management for beef cattle is now well proven and can now be recommended to farmers as an alternative to paddock grazing. 相似文献
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Two methods of improving hill land for sheep grazing have been compared on a Festuca/Agrostis pasture in mid-Wales. Ploughing and reseeding, following a pioneer crop, resulted in an excellent sward which remained productive at the end of the 8-year trial period. Surface seeding with light cultivation gave only a fair establishment of white clover, but no sown grass, during the same period. The production and financial results point to the superiority of the former technique where conditions are suitable and where increased grass production can be met by increased sheep stocking. Any worthwhile method must produce real improvement to the herbage. 相似文献
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以分枝型和主茎型各两个品种为材料，３种密度处理，２因子裂区设计试验，分析种植密度对大豆生长发育与产量的影响．结果表明：在中等栽培水平下，分枝型中熟、中晚熟品种以每穴单株、每公顷１６．０—１７．０万株，主茎型中熟品种以每穴双株、每公顷２０．０—２２．０万株比较适宜。 相似文献
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从(南农73-935×Beeson)F3株行和Co60γ射线辐照处理南农87C-38的M5株行分别发现2个育性异常材料NJS-18H、NJS-19H.后裔试验育性鉴定表明NJS-18H、NJS-19H不育株的雌性与雄性育性均不正常,不能正常结荚,可能为联会异常突变体,其不育性均受1对隐性基因控制.该2个突变体可能用作大豆雌雄配子发育及其相互遗传关系研究的材料. 相似文献
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耐水性大豆基木材胶粘剂两步法工艺研究 总被引：4，自引：4，他引：0
利用天然高分子聚合物开发无甲醛木材胶粘剂是人类社会发展的必然选择.在国际上,利用低温大豆粕制备生物质基木材胶粘剂具有相当长的历史.但是在传统豆胶制备方法中,碱等变性剂用量高达豆粕干重的6%～7%或更高,外加4%左右的石灰乳.豆胶中残碱对大豆蛋白的水解破坏难以得到控制,因此传统豆胶都不属于耐水胶粘剂.在本研究中,采用低碱量低液比高强度变性和均质处理分两段进行的工艺技术解决了这一矛盾.得到了制备符合国标Ⅱ类(耐热水)的大豆基木材胶粘剂的主要工艺参数并通过验证试验加以确定.最后把新法豆胶优化工艺与两个典型的传统豆胶制作配方做了比较.这种豆胶制备新工艺具有国际先进水平. 相似文献