放牧强度对牦牛生长的影响

两年的试验结果表明,牦牛在冬季个体增重与放牧强度呈显著的线性回归关系,但夏季则呈极显著的二次多项式回归关系。在不同放牧强度下,牦牛体重、日增重随着时间的变化分别呈极显著线性回归和高次多项式回归关系;在试验期间,牦牛的增重、每公顷增重与放牧强度均呈明显的线性回归关系。方差分析结果表明,处理间牦牛平均总增重差异显著(F=5.03>_0.05=3.68),新复极差测验结果表明,轻度放牧和中度放牧之间差异不显著,但二者和重度放牧间差异显著。     

高寒混播草地牦牛优化放牧强度的研究 Ⅰ以牦牛增重为目标研究牧草生长季的最佳放牧强度

垂穗披碱草Elymus nutans—星星草Puccinellia tenuiflora混播草地3个放牧季的牦牛放牧试验结果表明:相同放牧区每公顷草地牦牛总增重之间的差异不显著(P>0.05),同一放牧季各放牧区牦牛总增重之间的差异极显著(P<0.01),且各放牧季牦牛的个体增重与放牧强度均呈显著的线性回归关系;2003年单位面积草地牦牛增重随放牧强度的增加而增加,2004和2005年单位面积草地牦牛增重与放牧强度呈二次回归关系;通过二次回归方程计算得到:牧草生长季牦牛最佳放牧强度为7.23头/hm2。     

高寒混播草地牦牛优化放牧强度的研究I以牦牛增重为目标研究牧草生长季的最佳放牧强度

垂穗披碱草Elymus nutans-星星草Puccinellia tenuiflora混播草地3个放牧季的牦牛放牧试验结果表明:相同放牧区每公顷草地牦牛总增重之间的差异不显著(P>0.05),同一放牧季各放牧区牦牛总增重之间的差异极显著(P<0.01).且各放牧季牦牛的个体增重与放牧强度均呈显著的线性回归关系;2003年单位面积草地牦牛增重随放牧强度的增加而增加,2004和2005年单位面积草地牦牛增重与放牧强度呈二次回归关系;通过二次回归方程计算得到:牧草生长季牦牛最佳放牧强度为7.23头/hm2.     

安犏牛与牦牛设施化养殖技术试验研究

通过采用犏牛、牦牛犊牛培育技术结合设施化养殖技术,研究不同的饲养方式对犏牛、牦牛生长发育、增重效果及屠宰率的影响,研究结果表明,采用犊牛培育技术,6月龄犏牛公犊牛和牦牛公犊牛的体高、体斜长、胸围、管围都有不同程度的增长,体重也明显增加,与对照组相比,差异显著(P<0.05);采用设施化养殖技术,犏牛设施组的总增重及平均日增重显著高于牦牛对照组,差异显著(P<0.05);牦牛设施组、犏牛对照组和犏牛设施组的总增重及平均日增重显著高于牦牛对照组,差异显著(P<0.05)。犏牛设施组胴体重及净肉重分别为138.27±3.17kg和113.29±2.87kg,屠宰率和净肉率分别为58.47%和47.91%,犏牛设施组屠宰率和净肉率显著高于犏牛对照组,差异显著(P<0.05);牦牛设施组胴体重及净肉重分别为99.09±2.35kg和79.83±1.91kg,屠宰率和净肉率分别为57.46%和46.29%,与牦牛对照组和犏牛对照组相比,牦牛设施组和犏牛设施组的屠宰率和净肉率显著高于牦牛对照组和犏牛对照组,差异显著(P<0.05)。采用犏牛、牦牛犊牛培育技术结合设施化养殖技术,犏牛、牦牛的生长发育速度显著提高,总增重、日增重、屠宰率和净肉率显著高于传统放牧条件下的犏牛和牦牛。     

高寒牧区牦牛冬季暖棚育肥试验研究

试验结果表明 :在暖棚舍饲条件下 ,第 1组牦牛的绝对增重、相对增重分别比第 2组和对照组高 5 .9kg、4.94%和 3 1.44 %、2 6.5 9% ,第 2组比对照组高 2 5 .5 4kg和 2 1.65 % ,两处理之间同一放牧期牦牛的日增重之间差异极显著 (P <0 .0 1) ,处理内不同放牧期牦牛的日增重之间差异显著 (P <0 .0 5 ) ,而且牦牛的日增重与采食量之间呈极显著的线性回归关系Y =-aX +b ,(a >0 )。     

短花针茅草原上放牧强度对绵羊生产性能的影响

1985～1989年在内蒙古农牧学院哈雅教学牧场选用杂种羯羊在短花针茅草原上进行放牧强度试验，分析各处理对绵羊生产性能的影响，旨在探讨放牧强度与绵羊生产之间的关系，确定适宜的载畜率。研究结果表明，轻度放牧的绵羊体重显著高于中度和重度放牧（P＜0．01）；放牧期间轻度放牧绵羊的总增重量显著高于重度放牧（P＜0．01），各处理间绵羊掉源量无明显差异（P＞0．05）；轻度放牧绵羊净毛量显著高于中度和重度放牧（P＜0．01），而两者之间净毛量无显著差异（P＞0．05）；经济效益分析表明，载畜率为1．07ha／只·年的中度放牧是最为经济合理的放牧强度。     

高寒牧区牦牛育肥试验研究

试验结果表明 :天然草地不同牧草利用率下 ,牧草利用率为 3 0 %的绝对增重、相对增重和日增重比 5 0 %和 70 %的分别高 2 2kg和 8 1kg、2 3 4%和 8 5 1%、0 0 2kg和 0 0 7kg ,各处理间差异不显著 (P >0 0 5 ) ,但处理内不同放牧期间差异极显著 (P <0 0 1) ;天然草地、人工草地上不同年龄组条件下 ,天然草地上绝对增重和日增重分别高于人工草地上的 ,0 5岁犊牛组的相对增重高于对应的 1 5岁犊牛组 ,日增重各处理间差异不显著 (P >0 0 5 ) ,但处理内不同放牧期牦牛日增重差异极显著 (P <0 0 1) ;在暖棚舍饲条件下 ,高精料组 (第一组 )的绝对增重、相对增重和平均日增重分别比低精料组 (第二组 )和对照组高 5 9kg、4 94%、0 9kg和 3 1 44kg、2 6 5 9%、0 49kg ,低精料组 (第二组 )比对照组高 2 5 5 4kg、2 1 65 %和 0 4kg ,两处理之间同一放牧期牦牛的日增重差异极显著 (P <0 0 1) ,处理内不同放牧期牦牛的日增重差异显著 (P <0 0 5 )。     

短期放牧对青藏高原东北边缘高寒草甸土壤及微生物碳氮含量的影响

年际内短期放牧是青藏高原东北边缘地区草地利用的主要方式,而土壤有机碳和全氮含量是草地生产力维持的基石。以青藏高原东北边缘天祝县高寒草甸土壤为对象,研究了不放牧(对照)、轻度放牧(0.8头牦牛/hm2)、中度放牧(1.0头牦牛/hm2)和重度放牧(1.2头牦牛/hm2)条件下土壤有机碳和全氮以及土壤微生物量碳氮含量的变化特征。结果表明:重度放牧使土壤表层0～10cm和10～20cm全氮含量降低了12.5%和10.7%,中度放牧使10～20cm土层土壤有机碳含量增加了11.21%,其他各层全氮和有机碳含量并未随放牧强度变化发生显著变化;微生物量氮在0～10cm土层随放牧处理变化十分明显,轻度放牧、中度放牧和重度放牧下比对照分别增加了65.35%、25.23%、46.91%(P<0.05),而0～10cm土层微生物量碳在中度放牧处理下含量比对照显著增加(P<0.05),说明在表层相对于土壤碳氮,微生物量碳氮对短期放牧的反应更为灵敏。     

海晏县牦牛育肥试验效果分析

试验采用舍饲、放牧+补饲及放牧的饲养方式,对30头24月龄牦牛进行育肥试验研究,数据分析结果表明,舍饲组牦牛的平均日增重达到484.83 g,放牧+补饲组牦牛的平均日增重达到358.27 g,对照组牦牛的平均日增重达到117.11 g,舍饲组与放牧+补饲组及对照组牦牛的平均日增重对比,差异显著(P0.05);放牧+补饲组与对照组牦牛的平均日增重对比,差异显著(P0.05);研究表明,采用舍饲及放牧+补饲的育肥方式,显著提高育肥牦牛的增重效果,经济效益显著。     

放牧强度和放牧时间对牦牛干物质采食量及其表观消化率的影响

垂穗披碱草/星星草混播草地3个放牧季节的牦牛放牧试验结果表明:放牧强度和放牧时间对牦牛采食量均有极显著的影响(P<0.01),在放牧期内,牦牛干物质的采食量随放牧强度的增加而减小,而且随放牧时间的延续,各放牧区牦牛的干物质采食量均在8月5-20日达到最大;放牧强度对牦牛粪干物质的影响极显著(P<0.01),而放牧时间(季节变化)对它的影响不显著(P>0.05);极轻度和轻度放牧区牦牛干物质的消化率均在7月20日-8月5日达到最大,而中度和重度放牧区均在8月20日-9月5日达到最大。     

Long-term cattle gain responses to stocking rate and grazing systems in northern mixed-grass prairie

The effects of stocking rate and grazing system on gains of yearling beef cattle grazing rangelands have largely been addressed in short-term (< 10 years) studies, and often stocking rates are confounded within grazing systems with higher stocking rates for short-duration rotational grazing systems compared to season-long grazing. A grazing system (season-long and short-duration rotational grazing) × stocking rate (light: 16 steers/80 ha, 18.0 animal unit days/ha; moderate: 4 steers/12 ha, 30.1 animal unit days/ha; and heavy: 4 steers/9 ha, 40.1 animal unit days/ha) study was initiated in 1982 on northern mixed-grass prairie. Here, we report on the final 16 years (1991–2006) for yearling beef cattle gains. Average daily gains (kg/head/day) across all years with season-long grazing decreased with increasing stocking rate and grazing pressure. Heavy stocking rates reduced average daily gain by 16% and 12% compared to light and moderate stocking rates, respectively. In contrast to average daily gain, beef production (kg/ha) increased with increasing stocking rate and grazing pressure. Cattle gains were reduced by 6% with short-duration rotation compared to season-long grazing over the study period, with differences between systems observed in years with average, but not dry or wet, spring (April + May + June) precipitation. Grazing season gains (kg/head) and beef production both exhibited significant increasing hyperbolic relationships with spring precipitation, with the percentage of variation explained by spring precipitation substantially higher (62–83%) for beef production compared to grazing season gains (32–45%). The influence of spring precipitation on cattle gains suggests that incorporation of these relationships into modeling efforts for strategic planning and risk assessment will assist land managers in better matching forage and animal resources for greater sustainability in this highly variable environment.     

放牧强度对高寒草甸草场地上生物量和牦牛生长的影响

讨论了放牧强度对高寒草甸草场地上生物量和牦牛生长的影响，结果表明：放牧强度对地上生物量和牦牛生长有显著的影响。随着放牧强度的减轻，优良牧草（禾草＋莎草）比例提高，杂草（可食杂草＋毒杂草）比例降低。在2年的试验期内，三个处理牦牛的平均总增重有显著的差异（F＝5．03＞F0．05＝3．68），进一步做新复极差测验，30％和50％之间差异不显著，但它们和70％之间的差异均显著。     

垂穗披碱草/星星草混播草地优化牦牛放牧强度的研究

以植被和牦牛生产力变化为目标研究草地不退化的最大放牧强度,在垂穗披碱草/星星草高寒混播草地3年的牦牛放牧试验结果表明,1)优良牧草比例和牦牛个体增重的平均年度变化随放牧强度的增加而减小,牦牛个体增重和优良牧草比例的平均年度变化之间存在着正相关,因此确立了不同放牧强度下优良牧草比例的年度变化是评价高寒混播群落放牧价值的直接度量指标.2)虽然群落相似性系数和草地质量指数可以评价草场的相对变化,但相似性系数的变化与牦牛个体生产力没有显著关系,因而不能反映草场放牧价值的变化,而计算草地质量指数时,不同植物类群盖度的测定和适口性的判别受人为因素的干扰较大,因此它也不是一个很客观的指标.3)当放牧强度为9.97头/hm2时,优良牧草比例和牦牛个体增重的年度变化能维持基本不变,因此,可以认为该放牧强度是高寒人工草地生长季放牧不退化的最大放牧强度.     

Grazing pressure and acquisition of Ostertagia ostertagi in calves

The effect of stocking rate on the acquisition of Ostertagia ostertagi infection and performance of yearling calves grazing a marshland area in the southwest of Jutland (Denmark) was examined. During the early part of the grazing season, when grass growth was high and pasture infectivity low, there was little stocking rate effect on performance. However, during the late part of the grazing season (characterized by poorer grass growth and high pasture infectivity) gains were significantly lower at high, compared with moderate stocking. At both stocking rates, the beneficial effect of moving animals to aftermath in mid-summer was significant, but was most pronounced at the high stocking rate. Interactions between stocking rate and acquisition of parasitism are discussed in the light of grazing behaviour and climatic factors.     

Stocking rate and the productivity of Rhodes grass pastures on the Lilongwe plain,Malawi

An experiment was undertaken over three wet (summer) seasons to investigate the effects of different set stocking rates on animal performance from fertilised Rhodes grass pastures. The three set stocking rates were 2.5, 5 and 7.5 livestock-units/ha (1 livestock unit=342 kg liveweight). Pasture productivity was related to stocking intensity. Animal gain per hectare was directly related to stocking rate. Gain per animal, gain per livestock unit and number of grazing days were all inversely proportional to stocking rate. Animals on the low stocking rate were carried through almost to the end of the dry (winter) season with only small changes in liveweight. The practical significance of the results is discussed.     

不同放牧强度下高寒草甸植被特征和土壤养分变化研究

放牧作为最主要的生物干扰因子之一,影响着草地生态系统植被和土壤的生态进程。在自然放牧条件下,通过不同放牧强度的比较试验,对高寒草甸土壤营养成分及地上群落特征进行分析,为制定合理的放牧强度提供理论依据。结果表明:随着放牧强度加大,地上总生物量、物种丰富度在封育样地最高,在重牧样地最低,而封育、轻牧、中牧样地香浓-威纳多样性指数并没有显著的差异;禾草和莎草的地上生物量和总盖度在中牧条件下最高。与轻牧、中牧和封育样地相比,重牧样地的杂草有较高的地上生物量和总盖度;5月份土壤含水量随放牧强度增加而减少,7月份、9月份则相反;封育、轻牧、重牧样地的土壤容重显著低于中牧样地(P<0.05);在整个生长季节,重牧样地的pH值明显高于其他3个处理,而封育?轻牧?中牧3个样地pH值没有显著差异;在整个生长季节,封育、轻牧、中牧、重牧4个样地土壤有机碳含量随着放牧强度的增加而趋于下降,其中封育、轻牧、中牧3样地土壤有机碳含量都显著高于重牧样地(P<0.05);土壤的全氮含量在各放牧样地里并没有显著变化,而土壤氨态氮、硝态氮则在植物整个生长季节随着放牧强度的加大而增加;在整个生长季节里全磷含量最大值都出现在中牧样地里,速效磷含量表现出了和全磷一致的结果。因此,适度放牧是保护生物多样性,维持土壤养分以及提高草地生产力的有效途径;当高寒草甸由于退化导致生物量锐减,生物多样性丧失等严重后果时,围栏可以作为有效的恢复手段。     

Performance of light vs heavy steers grazing Plains Old World bluestem at three stocking rates

Live weight gains of light and heavy calves grazing Plains Old World bluestem at three stocking rates were evaluated during the summers of 1997 and 1998. Initial weights of mixed-breed light-weight steers (LHT) were 141 SD = 17 kg (n = 214) in 1997 and 160 SD = 23 kg (n = 193) in 1998. Initial weights of mixed-breed heavy steers (HWT) were 265 SD = 17 kg (n = 115) in 1997 and 248 SD = 13 kg (n = 126) in 1998. Initial stocking rates for both sizes of steers were as follows: light, 392 kg of live weight/ha; moderate, 504 kg of live weight/ha (increased to 616 kg live weight/ha in 1998); and heavy, 840 kg of live weight/ ha. Averaged gain and gain/hectare are reported as stocking rate by steer type within year. Heavy steers had greater ADG than LHT steers during both years. Forage intake, expressed as a percentage of BW, was greater (P = 0.05) for LHT (3.1%) than for HWT (2.8%) calves. Grazing time (min/d; 1998 only) was greater (P = 0.05) for LHT (665) than for HWT (624) steers. Forage CP and in vivo digestible organic matter (DOM) were slightly greater (P < 0.05) in pastures grazed by HWT vs LHT cattle. Gain/hectare was greater (P < 0.05) for LHT than for HWT calves at all three stocking rates during both years. A linear decline in ADG was observed (P < 0.07) as stocking rates increased for HWT steers in 1997 and LHT steers in 1998. However, ADG did not decline with increasing stocking rate for LHT calves during 1997 or HWT calves during 1998. Forage intake was not different among stocking rates in either 1997 or 1998. Grazing time was greatest (P < 0.05) for steers in the moderate and heavy stocking rates. Forage in vivo DOM decreased (P < 0.05) as stocking rate increased. Both LHT and HWT steers had lower (P < 0.05) ADG at all three stocking rates during 1998 compared with 1997. Despite lower ADG, LHT steers had greater gain/hectare than HWT steers during both 1997 and 1998.     

补饲与不补饲条件下3种放牧率对高寒草地牧草与家畜生产的影响

通过补饲和不补饲条件下放牧率对高寒草地牧草和家畜生产影响的研究,结果表明,3种放牧率对草地牧草产量影响不大,组间差异不显著(P>0.05)。放牧率影响羯羊体重。在补饲条件下,羯羊日增长量随放牧率减小而增加,组间差异显著(P<0.05);不补饲使羯羊减重,羯羊日减重量随放牧率减小而降低。同时,放牧率影响羯羊肉用性能和肉的品质。在补饲条件下,草地生物学效率明显高于不补饲组,且中组比低、高组高,草地生产能力最大。由此得出,高寒草地以中等放牧率为最佳,即1.8只/hm~2,且补饲效果最明显。