农牧交错带人工草地放牧对奶牛生产性能的影响

研究不同放牧制度和强度对在“多年生禾草+紫花苜蓿(Medicago sativa)”人工草地上放牧奶牛的采食量、产奶量、乳成分及体重和体况分的影响。结果表明:轮牧制奶牛的采食量低于连续放牧制,中度放牧低于轻度放牧。轻度轮牧有较高的体增重和较小的体况分损失,连续放牧则相反。轮牧制奶牛的产奶量显著高于连续放牧制,中牧高于轻牧。不同放牧处理对乳成分的影响不显著,轻度轮牧的乳脂率低于中度轮牧和连续放牧,轻度轮牧的乳蛋白最高,乳糖和乳干物质含量则无显著变化。     

不同放牧制度和强度下奶牛生产性能的研究──2.放牧对奶牛产奶量及体增重的影响

本文作者在湖南南山牧场首次研究了不同放牧制度(分区轮牧和连续放牧)和放牧强度(0.467,0.667和0.867ha/头)下在多年生黑麦草/白三叶人工草地上放牧的黑白花奶牛产奶量、乳比重及体重的变化。结果表明:轮牧制奶牛的产奶量显著高于连续放牧制(1632.5vs.1462.3kg/头)。不同放牧强度下,奶牛的产奶量以中等放牧强度最高,轻牧次之,重牧最低,分别为1724.5、1571.1和1331.2kgh头。放牧期间两种放牧制间奶牛平均日增重差异不显著,以轮牧制较高(0.224vs.0.205kg/头·天);三种放牧强度间奶牛的平均日增重差异也不显著,由大到小依次为B3>B2>B1,分别为0.242、0.225和0.176kg/头·天。不同放牧处理对牛奶比重影响不大。这说明在本试验条件下,放牧制度和放牧强度对奶牛平均日增重增加影响不显著,但对奶牛的产奶量有显著的影响。     

不同放牧制度和强度下奶牛生产性能的研究──1.放牧对牧草采食量及营养摄入量的影响

本文作者在湖南南山牧场研究了两种放牧制度（分区轮牧和连续放牧）和三种放牧强度（0．467，0．667和0．867ha／头）对处于泌乳中后期的黑白花奶牛在多年生黑麦草／由三叶人工草地上的放牧来食量、采食植物组成、营养摄入量的影响。结果表明：轮牧制奶牛的采食量低于连续放牧制，但其口粮组成中黑麦草和白三叶的比例高于连续放牧，故粗蛋白质、总能、钙和磷的日摄入量也低于轮牧制奶牛。随放牧强度的增加，奶牛的来食量、以及粗蛋白质、酸性洗涤纤维、总能、钙和磷的摄入量均有所增加，但三种放牧强度间差异并不显著。放牧强度越大，家畜日粮组成中黑麦草和白三叶的比例越大，而枯草和杂草所占比例越小。这说明在南山试验条件下，放牧制度和放牧强度对奶牛的采食量及各种营养物质的日摄入量有一定影响。     

奶牛放牧对北方农牧交错带人工草地植被的影响

研究了不同处理奶牛放牧对混播人工草地植被的影响。结果表明,牧草现存量随着放牧强度的增加而降低,轻牧比中牧高7.28%,且轮牧高于连续放牧1.99%,轮牧对紫花苜蓿和无芒雀麦的再生有利。随放牧强度增加,紫花苜蓿和无芒雀麦重要值下降,蓝茎冰草和新麦草增加。放牧对牧草的茎叶比有显著影响,放牧后4种牧草的茎叶比均有下降,连续放牧高于轮牧。根系主要集中在土壤表层0~10 cm,约占0~30 cm总量的70%,且其生物量也以轮牧制较高,随放牧强度的增加而下降。     

不同放牧制度下奶牛对多年生黑麦草／白三叶草地土壤特性的影响

本项试验在湖南南山牧场进行，旨在研究不同放牧制度下奶牛对多年生黑麦草／白三叶人工草地土壤物理和化学特性的影响。表明，放牧制度对黑麦草白三叶人工草地土壤的物理结构有一定影响。轮牧草地上土壤的容重较小，含水量较高，孔隙度增加；而连续放牧使土壤的紧实度增加，容重上升，透气为差，含水量下降；放牧对土壤物理特性的影响将随着土 深度的增加而减轻，轮牧草地的土壤多数养分尤其是速效和速效钾的含量均高于连牧草地。     

不同放牧制度对亚高山草甸土理化性质的影响

以新疆亚高山草甸土为研究对象,研究了自由放牧和划区轮牧对土壤理化性质的影响。结果表明：短期改变放牧制度对草地土壤养分含量影响不显著,理化性质对其响应程度亦有所不同。轮牧土壤碱解氮、有机质的含量稍低于自由放牧,土壤速效钾和有效磷的含量均高于自由放牧。不同放牧制度对草地土壤容重、孔隙度、机械组成的影响不大。     

放牧绵羊对恢复阶段退化草场营养物质含量的影响

选取内蒙古自治区克什克腾旗达来诺日镇典型草原区封育恢复中天然放牧草场,于2008年6～10月进行毛肉兼用细毛羊的暖季放牧试验.采用2×5完全随机试验设计,设定不同放牧方式(不放牧,连续放牧,四区、五区、六区轮牧)及2种放牧强度,研究围封过程中放牧绵羊对封育草场牧草营养物质含量的影响.结果表明,不放牧区牧草初水分、粗蛋白质、粗脂肪和粗灰分含量显著高于轮牧和连续放牧区,酸性洗涤纤维和中性洗涤纤维含量显著低于放牧区;随着放牧季节的延续,不放牧区牧草营养价值下降速度最慢,轮牧区次之,连续放牧处理下降最明显;四区、五区和六区轮牧处理间牧草营养物质含量变化差异不显著.放牧方式与放牧强度对草场营养物质含量动态变化表现出不同程度的瓦作效应.因此,在放牧强度适中时,划区轮牧能够体现其优越性,随着牧草生长季的延续,较好地保存牧草的营养价值.     

混播人工草地不同放牧制度下草畜互作试验研究

试验于2010年6～9月在中国农业科学院草原研究所农牧交错区试验示范基地的混播人工草地上进行。试验分为划区轮牧组和连续放牧组,轮牧组与连续放牧组各设3个重复,轮牧区每个重复各有5个小区,每个小区放牧时间为6d。试验结果显示,不同放牧制度对各组草地牧草的干物质产量影响不显著;对各组草地牧草的营养物质影响差异显著(P<0.05);划区轮牧组牧草的粗蛋白质(CP)含量有高于同期连续放牧草地牧草的趋势,而中性洗涤纤维(NDF)含量低于连续放牧草地的牧草;对绵羊增重影响组间差异不显著。     

荒漠草原不同放牧制度对土壤理化性质的影响

在短花针茅荒漠草原对比研究了划区轮牧和自由放牧两种放牧制度对草地土壤理化性状的影响。结果表明:划区轮牧与自由放牧相比,表层土壤容重下降、孔隙度增加、土壤机械组成优化;划区轮牧表层土壤质地有所改善;土壤中全氮、碱解氮、全磷、速效磷、速效钾以及有机质含量均较自由放牧区有所提高。     

绵羊放牧方式及强度对围封恢复草场牧草细胞壁成分及营养价值的影响

选取内蒙古自治区典型草原区封育恢复中天然放牧草场,进行毛肉兼用细毛羊的暖季放牧试验.采用2×5完全随机试验设计,设定不同放牧方式（不放牧,连续放牧,四区、五区、六区轮牧）及2种放牧强度（1.0,1.4 hm2/un.sh）,运用酶分析方法分析比较了围封过程中放牧绵羊对封育草场牧草细胞壁成分月动态变化及营养价值的影响.结果表明,整个暖季放牧期内,不同放牧区牧草营养物质含量主要受到放牧方式的显著影响（P＜0.05）.具体表现为,不放牧处理牧草细胞壁有机物（OCW）含量始终显著低于各放牧处理,不同放牧处理间没有明显差异;划区轮牧处理牧草始终保持着较高的消化性部分且显著高于连续放牧处理;不放牧处理牧草始终保持着较高的Oa和较低的Ob,而连续放牧处理与其相反,各轮牧处理间没有显著差异;轮牧处理总可消化养分（TDN）和代谢能（ME）含量较高,尤其在牧草生长旺盛期（八月份）,六区轮牧放牧场牧草可利用营养物质含量最高,营养价值最高.     

棉茬地放牧对母羊繁殖性能及血液性状的影响

利用能繁母羊在棉茬地进行冬季放牧,探讨了棉茬地放牧对母羊繁殖性能及血液生化指标的影响。结果表明,棉茬地地上生物量为6 178.6 kg·hm-2,其中棉叶、棉桃壳等可采食部位约占65%。母羊的日均干物质采食量为1.98kg·只-1。与该区域舍饲母羊群相比,棉茬地放牧母羊后羔羊初生重偏低而死亡率高达12.87%,繁殖成活率降低(P0.05);随着放牧时间的推移,母羊血液游离棉酚浓度呈上升趋势,放牧结束时血液游离棉酚浓度达到131.70mg·L-1;放牧组母羊的血液中白细胞数量显著高于舍饲组(P0.05),而血小板数目、尿素氮浓度和镁浓度显著低于舍饲为主的母羊群(P0.05)。棉茬地作为冷季放牧利用地,能降低饲养成本,但对母羊的繁殖能力和健康有一定影响,建议在棉茬地放牧的同时进行适当补饲。     

喀斯特山区草地施肥对放牧乌蒙半细毛羊抗氧化系统功能的影响

为选择草地施肥的肥料种类,减少施肥对乌蒙半细毛羊产业的影响,在威宁县凉水沟种羊场多年生人工草地开展施肥和放牧试验。 结果表明:凉水沟种羊场人工草地牧草铜含量相对较低,但仍高于乌蒙半细毛羊营养需要标准;施肥极显著增加牧草氮含量(P<0.01),各施肥处理之间没有明显差异。硫酸铵施肥显著增加牧草硫和锌含量(P<0.01),显著降低了牧草硒的含量(P<0.01)。放牧试验结束时,施硫酸铵草地的乌蒙半细毛羊血液中铜、铁和硒的含量极显著低于施硝酸铵草地和对照组(P<0.01), 动物血液锌和硫含量极显著高于硝酸铵施肥牧场和对照组(P<0.01)。硫酸铵施肥牧场的乌蒙半细毛羊血红蛋白、红细胞压积容量极显著低于硝酸铵施肥牧场和对照牧场(P<0.01),血清铜蓝蛋白含量、血清超氧化物歧化酶活力、血清谷胱甘肽过氧化物酶活力和血清过氧化氢酶等抗氧化酶的活力极显著低于硝酸铵施肥牧场和对照牧场(P<0.01),丙二醛的含量显著高于硝酸铵施肥牧场和对照牧场(P<0.01)。血液其他矿质元素和血液指标及血清生化值在2个施肥处理和对照之间均差异不显著。 因此得出结论,草地施肥的种类需要根据土壤矿物质分布和含量情况确定,铜含量低的牧场不适合硫酸铵施肥,硫酸铵施肥明显影响了乌蒙半细毛羊机体抗氧化系统功能。     

Effect of Sward Height on Pasture Nonstructural Carbohydrate Concentrations and Blood Glucose/Insulin Profiles in Grazing Horses

Six mature stock-type geldings with maintenance only requirements were used in a randomized cross-over design to determine the effect of sward height on pasture plant nonstructural carbohydrate (NSC) concentrations and blood glucose and insulin concentrations. Horses were randomly assigned to one of two tall fescue (Lolium arundinaceum Schreb cv Max-Q, Pennington Seed, Madison, GA) grazing cells (0.37 ha) having two different sward heights for a period of 7 days: (1) short (approximately 15 cm; n = 3) or tall (between 30 and 40 cm; n = 3). After the first 7-day period, treatment groups were reversed by moving horses to ungrazed cells having similar characteristics to those used in the first 7 days, so that all horses receive all treatments resulting in six observations per treatment. Both short and tall grazing cells were mowed to a height of approximately 15 cm 32 days before the experiment starts. The short grazing cells were removed to approximately 15 cm at 11 days before the start of the first 7-day period and again 1 day before the start of each 7-day period. All horses had access to pasture for 10 h/d beginning at 8 AM and ending at 6 PM. Although not at pasture, all horses were individually housed in 3.7 × 12.2 m partially covered pens containing automatic water troughs and a crushed stone surface. Herbage mass (kg DM/ha) was determined by use of a falling plate meter for each pasture to ensure that both groups of horses had adequate dry matter to provide grazing for at least 7 days. On day 7 of each period, jugular venous blood samples were collected from each horse before being turned out to pasture, and then at 2, 4, 6, and 8 hours after turn-out. Pasture samples were also collected from each grazing cell at the same time blood samples were taken. Serum and plasma from blood samples were harvested and analyzed for insulin and glucose concentrations, respectively. Pasture samples were analyzed for water soluble carbohydrate (WSC), ethanol soluble carbohydrate (ESC), and starch. The sum of WSC and starch were used as an estimate of NSC. Area under the curve (AUC) and peak concentration were calculated for both plasma glucose (PPG) and serum insulin (PSI) concentration and were analyzed using analysis of variance for randomized cross-over designs. Pasture WSC, ESC, starch, and NSC concentrations were analyzed using analysis of variance for randomized complete block design. A P value of < .05 was considered significant. Mean pasture plant NSC, WSC, and ESC concentrations were lower (P < .001) in short as compared with tall. Pasture plant starch concentration was not different between treatments. Mean pregrazing plasma glucose concentrations, PPG concentrations, and plasma glucose AUC were not affected by treatment. Mean pregrazing serum insulin concentrations were not affected by treatment. Mean PSI and insulin AUC were greater (P < .01) when horses grazed tall, as compared with short. In conclusion, decreasing the sward height by mowing pasture decreased NSC, WSC, and ESC concentrations and subsequently decreased the postprandial insulin response of horses grazing the pasture. These findings may be important in developing strategies aimed at preventing insulin resistance in grazing horses.     

Effect of soluble glass bolus administration on the blood selenium concentration in grazing Philippine goats under backyard conditions

The present study was conducted to determine the effects of selenium (Se) soluble glass bolus (SGB) on blood Se concentrations of mixed‐bred (native × Anglo Nubian) pregnant does weighing between 15 and 52 kg and grazing on natural pastures in the Philippines. The control group, consisting of 28 does, was not administered with SGB, while 23 does were administered with SGB every 6 months for a period of 12 months. Forage and blood samples in both groups were collected every 2 months. Their Se, sulfur, calcium, phosphorus, magnesium, copper and zinc concentrations were analyzed using the wet digestion method. The results showed that the grazed forage had concentrations of all these minerals that were far higher than the accepted critical lower levels. The Se concentration was higher (P < 0.05) in the dry season than in the rainy season, especially in the whole blood collected from the does and newborn kids. In both groups the Se concentration in the kids tended to increase during the suckling period but decreased after weaning. Kids born to the SGB does had higher whole blood Se concentrations (P < 0.05) than those born to the control does. However, the administration of SGB to the does did not affect any blood mineral concentrations except for Se in the grazing does and their kids. The animals did not exhibit any clinical signs of mineral deficiencies or toxicities during the experimental period.     

草地施肥对牧草和放牧贵州半细毛羊的影响

为评价草地施肥对放牧贵州半细毛羊的影响,在威宁县凉水沟退化人工草地上进行了(NH₄)₂SO₄和NH₄NO₃施肥和放牧试验。结果表明,草地施肥极显著增加牧草氮(N)含量,但各施肥处理之间没有显著差异。(NH₄)₂SO₄施肥极显著增加牧草S、Mn和Zn含量,减少牧草Se含量。试验结束时,施(NH₄)₂SO₄草地半细毛羊血液中Cu、Fe和Se含量极显著低于施NH₄NO₃草地和对照草地,家畜血液Mn、Zn和S含量极显著高于NH₄NO₃施肥牧场和对照牧场。(NH₄)₂SO₄施肥牧场贵州半细毛羊血红蛋白(Hb)和红细胞压积容量(PCV)以及血清Cp含量、血清SOD活力、血清GSH-PX活力和血清CAT活力极显著低于NH₄NO₃施肥牧场和对照牧场,血液其他矿质元素和血液指标及血清生化值在2个施肥处理和对照之间均差异不显著。因此得出结论,威宁县凉水沟天然草地不适合用(NH₄)₂SO₄施肥。     

Effect of ammonium sulfate fertilization on bahiagrass quality and copper metabolism in grazing beef cattle

To assess the impact of S fertilization on bahiagrass (Paspalum notatum) quality and Cu metabolism in cattle, two studies were conducted during the summer grazing season (1999 and 2000). Pasture replicates (16.2 ha; n = 2/treatment) received the same fertilizer treatment in each growing season, consisting of 1) 67 kg N/ha from ammonium sulfate (AS), 2) 67 kg N/ha from ammonium nitrate (AN), and 3) control (no fertilizer; C). Forage sampling was conducted at 28-d intervals following fertilization by the collection of whole plants (four samples/pasture) in randomly distributed 1-m2 grazing exclusion cages and analyzed for CP, in vitro organic matter digestibility, S, P, Ca, K, Mg, Na, Fe, Al, Mn, Cu, and Zn. To determine the effect of fertilizer treatment on liver trace mineral concentrations in grazing cattle, random liver tissue samples were collected (n = 12; four/treatment) at the start and end of the study period in 2000. Ammonium sulfate fertilization increased (P < 0.001) forage S concentration in both years. Plant tissue N concentrations were increased by N fertilization, regardless of source, in 2000, but not in 1999. Cows grazing AS pastures had lower (P < 0.05) liver Cu concentrations at the end of the study period in 2000 compared to AN and C. In Exp. 2, 37 Cu-deficient heifers grazing AS fertilized pastures were obtained from the same location and allocated to one of two treatments, consisting of supplements providing 123 mg/d of either inorganic (Cu sulfate; n = 12) or organic (Availa-Cu; n = 15) Cu. Treatments were delivered for 83 d. Liver Cu increased over time in all heifers regardless of treatment; however, heifers supplemented with Availa-Cu tended (P = 0.09) to have higher mean liver Cu concentrations than those receiving Cu sulfate. The results of these studies indicate that AS fertilization of bahiagrass increases forage S concentrations. When provided free-choice access to a complete salt-based trace mineral supplement, cows grazing AS-fertilized pastures had lower liver Cu concentrations than cows grazing pastures fertilized with AN; upon removal from high-S pastures, cattle were able to respond to Cu supplementation.     

Effect of posttransportation grazing on the physiological condition and meat quality traits of Black Bengal goats

This study was designed to reveal the role of posttransportation grazing on the physiological condition and meat quality traits of Black Bengal goats. Twenty‐four castrated male Black Bengal goats were divided into a control (untransported) group and three treated groups: Walking and Transportation with Human Interference group (WTHI) (30 min walking before 6 hr transport and then 30 min walking with human interference), posttransportation grazing for 48 hr (PTG1), and posttransportation grazing for 72 hr (PTG2). The WTHI and PTG1 groups had a significant reduction in their blood concentrations of tri‐iodothyronine (T₃) and thyroxine (T₄), and a significantly higher neutrophil and lymphocyte (N:L) ratio compared with those of the control group. Blood concentrations of T₃ and T₄ and the N:L ratio of PTG2 returned to the control level after 72 hr of grazing. The final pH and water‐holding capacity values of meat were significantly higher in the WTHI group than in the control group, but those in the PTG2 group returned to the control level after 72 hr of grazing. These results demonstrate that posttransportation grazing for 72 hr is effective for recovering from damage induced by transportation stress.     

The application of a selenium fertiliser for the correction of marginal deficiencies in grazing sheep

A commercial fertiliser, consisting of a poorly soluble barium selenate core with a coating of highly soluble sodium selenite, was evaluated in 2 trials for the provision of selenium (Se) to grazing sheep. The fertiliser was administered at a level of 1 kg per hectare to 3 of 6 kikuyu paddocks during 1995 and 1996 in Trial 1, while the other paddocks were left untreated. The Se status of SA mutton merino ram lambs, as reflected by whole blood, liver and kidney Se concentrations, was elevated (P < 0.01) for at least 5 months after application of the fertiliser. Whole blood and liver Se concentrations of animals grazing unfertilised control paddocks were indicative of a subclinical Se deficiency at times (<100 ng Se/ml whole blood and <300 microg Se/kg liver dry matter). In Trial 2, 4 of 7 paddocks on which an oat fodder crop was established were treated with the Se fertiliser during 1995 and 1997. The remaining 3 paddocks were left unfertilised as controls. Groups of 10-15 pregnant SA mutton merino ewes were introduced to these paddocks within 2 weeks of parturition. These ewes and their progeny utilised these paddocks for a mean (+/- SD) period of 41 +/- 8 days after parturition. The whole blood Se concentrations of these ewes and their offspring were elevated (P < 0.01) relative to their contemporaries utilising control paddocks. No suggestion of a subclinical Se deficiency was discernible in animals grazing control paddocks, although whole blood Se levels approached 100 ng Se/ml during 1997. The application of Se fertiliser did not result in improvements in ewe reproduction or lamb growth. There was a suggestion of an improvement (P = 0.21) in mean (+/- SE) lamb survival on paddocks receiving Se fertiliser compared to control paddocks (71.5 +/- 4.6% vs 62.2 +/- 5.3% respectively).     

不同利用方式下草地优势植物的生态化学计量特征

在内蒙古温带草原围封、放牧和割草3种不同利用方式下,测定了大针茅、冷蒿和羊草3种优势种植物的化学计量元素,探讨了草地不同利用方式下优势种植物的化学计量特征响应机制。结果表明,3种优势种植物的C、N、P含量及其计量比在不同利用方式下均有明显的季节变化;不同利用方式、不同物种以及二者的交互作用均对N、P含量及C∶N、C∶P和N∶P有显著的影响,其中,C含量比较稳定,不同的利用方式对其无显著影响,N含量在整个生长季内总体呈下降趋势,放牧样地3种植物叶片的N、P含量均高于割草和围封样地,说明放牧增加了植物N、P的含量。植物生长普遍受到N的限制,土壤养分特征在不同利用方式间也存在一定的差异,围封样地表现为更加缺N,而放牧样地更加缺P。放牧样地有机质、C、N和P含量均高于割草和围封样地,说明适度放牧能提高土壤养分的含量,有利于植物的生长。     

Implant and copper oxide needles for steers grazing Acremonium coenophialum-infected tall fescue pastures: effects on grazing and subsequent feedlot performance and serum constituents.

Two experiments were conducted to compare the effects of a progesterone-estradiol implant (PEI) with no implant (NI) and 20 g of copper oxide needles (CuON) with no CuON on grazing, subsequent feedlot performance, and selected serum constituents of steers. In Exp. 1, 114 Limousin crossbred yearling steers (317 kg average initial BW) were stocked continuously on Acremonium coenophialum-infected tall fescue (Festuca arundinacea Schreb.)-ladino clover (Trifolium repens L.) pastures (C) or were rotated to bermuda grass (Cynodon dactylon [L.] Pers.) during summer months (R) of two consecutive years. Implant and copper treatments were applied within pasture. Blood samples were collected four times during each grazing season. Continuously stocked steers had greater (P less than .05) grazing gain, less (P less than .10) feedlot gain, and heavier (P less than .05) carcass weights than R steers did. Implanted steers had greater (P less than .05) pasture but lesser (P less than .05) feedlot gains than did NI steers. Prolactin concentrations were greater (P less than .05) from R than from C steers in late summer 1988. Ceruloplasmin was greater (P less than .01) with CuON than without on the last three and last two sampling dates in 1988 and 1989, respectively. In Exp. 2, blood samples were collected twice from 40 mixed-breed steers (283 kg average initial BW) receiving the same implant and copper treatments as in Exp. 1 and grazing infected fescue for one season. Serum ceruloplasmin and copper concentrations were increased (P less than .01) by CuON, but other measurements did not differ among treatments. Summer grazing of bermuda grass increased serum copper, ceruloplasmin, and prolactin but decreased grazing performance. Implanting increased grazing performance. Copper oxide needles increased serum ceruloplasmin and copper concentrations but did not affect steer performance.