甘南高寒牧区3种饲草不同种植模式下的生产性能及经济效益

为明确甘南高寒牧区3种饲草不同种植模式的生产性能及经济效益,设置了秋播小黑麦(×Triticale Wittmack)套作式复种箭筈豌豆(Vicia sativa)、50%春播小黑麦混播50%箭筈豌豆、小黑麦秋季单播、箭筈豌豆春季单播和燕麦(Avena sativa)春季单播5个处理,分析不同处理的干草产量、营养价值(粗蛋白含量、酸性洗涤纤维含量、中性洗涤纤维含量)、经济效益及土壤养分含量。结果表明,秋播小黑麦套作式复种箭筈豌豆和50%春播小黑麦混播50%箭筈豌豆的干草产量分别为14.06和12.31 t·hm^–2,纯收益分别为6 286和11 011元·hm^–2,显著高于3种单播模式(P <0.05),且显著提高了土壤的全氮含量,可作为甘南高寒牧区高效种植模式进行种植推广。     

Bermudagrass management in the Southern Piedmont USA. V: Gastrointestinal parasite control in cattle

Parasite-free pastures would improve cattle health and performance, resulting in possible economic return to producers. Our objective was to determine the effect of a single series of anthelmintic treatment of steers prior to stocking on Coastal bermudagrass pastures, during five consecutive summers, on the parasite burden in cattle. The site for this experiment had been conventionally cropped for several decades, with no exposure to cattle, and would be expected to be relatively free of nematode larvae. The experimental design was a randomized complete block (landscape features) with a split plot arrangement of treatments where main plots were pasture fertilization treatments (mineral, clover plus mineral, and broiler litter) and split plots were low and high forage mass. Anthelmintic treatment included pour-on ivermectin on day -21, albendazole on day -7, and injectable ivermectin 48 h prior to stocking of pastures, with the cattle remaining in drylot during the 48-h period prior to being placed on the experimental paddocks. All steers received only one series of treatments during any given year. Yearling Angus steers (Bos taurus) were managed in a put-and-take grazing system with three "tester" steers assigned to each paddock and "grazer" steers added or removed at 28-day intervals. From 1994 to 1998, steers grazed the paddocks for a 140-day period from mid May until early October each year. Fecal samples for worm egg counts were obtained on day 0 and at 28-day intervals, thereafter. On all sampling days after day 0, samples were obtained only from tester animals. Over the 5-year period, the mean eggs per gram of feces (epg) gradually increased from 0 (following treatment) to a mean of 2.2 (range from 0.7 to 3.0) by the end of the grazing season (the last sampling date) in October. Although the epg were not zero, they were below threshold levels that would allow development of a parasite burden in cattle. In traditional management systems, cattle graze parasite-contaminated pastures; therefore, parasites negatively impact growth and productivity throughout the entire grazing period. Periodic anthelmintic treatments simply give a temporary reprieve from those parasitic infections. Conceptually, using the current grazing system, it should be possible to maintain these pastures in a parasite-free status indefinitely; however, from a drug resistance perspective, it would be most applicable in sod-based rotation systems where cattle graze from two to five years before land is returned to row-crops. By removing the effect of parasites, cattle can grow without the physiological constraints that gastrointestinal parasites place on appetite, digestion, nutrient utilization, and general well being.     

不同类型草地牧草消化率季节动态与营养品质的关系研究

试验选用5只瘤胃瘘管羊,用尼龙袋法对采自甘肃玛曲高寒草甸、沼泽化草甸、甘肃张掖平山湖荒漠草原及新疆温性草原天然混合牧草的干物质消化率(DMD)和营养成分进行测定。结果表明,高海拔地区的高寒草甸和沼泽化草甸牧草干物质消化率显著高于低海拔地区荒漠草原,且随着时间的推移,高寒草甸和沼泽化草甸牧草干物质消化率先升高后降低,且在6月体内消化率达到最高,而平山湖荒漠草原表现相反趋势。新疆温性荒漠草原则随着季节的变化,从花期—果期—枯草期牧草干物质消化率逐渐降低。玛曲高寒草甸牧草干物质消化率与牧草粗蛋白含量(CP)呈极显著正相关(P<0.01),与牧草中酸性洗涤纤维(ADF), 中性洗涤纤维(NDF)呈极显著负相关(P<0.01);牧草生育期与CP含量和DMD呈极显著负相关,与DM, ADF, NDF均呈极显著正相关(P<0.01),说明在高寒牧区,6,7和8月牧草营养价值较高,可满足放牧家畜维持和生产能量需要。     

Effect of forage legumes and anthelmintic treatment on the performance, nutritional status and nematode parasites of grazing lambs

Recent studies in New Zealand and the UK have shown that certain forages reduce parasitic infection in sheep. The aim of this experiment was to investigate the effects of legume forages compared to ryegrass on interactions between production, nutritional status and nematodes in grazing lambs. Twenty-four male lambs per forage treatment, half of which were treated with anthelmintics on Day 0, grazed monocultures of lucerne (Medicago sativa), red clover (Trifolium pratense) and white clover (Trifolium repens) and were compared with lambs grazing perennial ryegrass (Lolium perenne). Individual faecal egg counts (FEC) and liveweight were determined every 7 days for 56 days, after which half the lambs were slaughtered to determine total nematode intensities (TNI). Results showed that lambs grazed on red or white clover, but not lucerne, had lower pooled mean FEC and improved liveweight performance compared to lambs grazing ryegrass. Lambs treated with anthelmintics had higher TNI compared to lambs not treated, due to a trend for more adult nematodes in lambs grazing lucerne and treated with anthelmintics than all other lambs, except those grazing red clover and also given anthelmintics. Lambs grazing white clover tended to have fewer adult nematodes than lambs grazing other forages. Examination of the nematode species showed a change in female T. circumcincta occurred in all lambs following anthelmintic treatment and that the forage species grazed by lambs affected individual parasite species. Lambs grazing white clover had fewer male and adult T. circumcincta compared to lambs grazing other forages, and lambs grazing lucerne had fewer adult T. circumcincta compared to lambs grazing ryegrass or red clover. Data on small intestine TNI showed that lambs grazing lucerne and given anthelmintics had more male adult nematodes than other lambs, except those grazing red clover and treated with anthelmintics. Results indicate that lucerne and red clover both increase the re-infection of grazing lambs with Trichostrongylus species compared to ryegrass following anthelmintic treatment. In conclusion, legume forages have the potential to contribute to the control of abomasal but not small intestine nematode parasites in finishing lamb systems.     

Intake and digestibility by wethers as influenced by forage morphology at three levels of forage offering

Animals on pasture do not always have the opportunity for ad libitum consumption. Our objectives were to determine effects of intake level on digestibility of 12 grass hays, and to relate differences in intake and digestibility to proportions of leaf blade, leaf sheath and stem. In each of two periods, 24 wethers were offered one of 12 hays at three consecutive levels of feeding: (L1) ad libitum, allowing 15% refusal; (L2) restricted to 100% of hay consumed ad libitum by individual wether during L1; and (L3) 1.8% of BW on a DM basis. Hays offered included two sorghum-sudan, four barley, four oat and two pearl millet. Hays were similar in NDF concentration but differed in morphological composition Organic matter intake averaged 1.99 +/- .04, 1.79 +/- .04 and 1.52 +/- .01% of BW for L1, L2 and L3, respectively. Organic matter digestibilities averaged 71.8 +/- .55 72.4 +/- .60 and 72.3 +/- .65% for L1, L2 and L3, respectively. Intake SEM within hays were lower with restricted intakes (L3), whereas the opposite was observed for the SEM for digestibility. Forage morphological composition within feeding level influenced intake and digestibility by altering diet selection capabilities of wethers. Wethers did not consume equal NDF amounts, ranging form .95 to 1.47% of BW, because hays differed in morphological composition. Ash-free ADF and 72% sulfuric acid lignin were higher (P less than .01) in stem than in blade or sheath. In vivo digestibilities measured under restricted feeding conditions were related more closely (P less than .05) to in vitro estimates of digestibility than were digestibilities measured under ad libitum conditions (r = .72, .79 and .85 for L1, L2 and L3, respectively). This study demonstrates that variation in morphological characteristics of forages may account for part of the difference in voluntary intake of forages of similar chemical composition. New knowledge in this area will be valuable in developing improved forage quality prediction procedures.     

Seasonal and Diurnal Changes in Starch Content and Sugar Profiles of Bermudagrass in the Piedmont Region of the United States

Seasonal and diurnal patterns of sugar accumulation in bermudagrass (Cynodon dactylon) pastures were monitored to evaluate risk factors for pasture-associated laminitis of ponies and horses. Bermudagrass was collected from four plots in the morning and afternoon on a weekly basis, from mid-July until late August. Tissue was air-dried to simulate hay, or frozen to retain the sugar profiles of fresh pasture. Samples were analyzed colorimetrically for total water-soluble and ethanol-soluble carbohydrates, and electrochemically for starch. In addition, sugars were separated and quantified by high-performance liquid chromatography coupled to pulsed amperometric detection. The dominant sugars in extracts were glucose, fructose, and sucrose. Some minor peaks, corresponding to tri- and tetrasaccharides, were also detected in some extracts. Starch increased over time in fresh and dried tissue, and concentrations varied diurnally in fresh, but not in dried tissue (P = .021). Sucrose in dried tissue decreased and then increased, with higher concentrations than in fresh tissue on all sampling dates (P = .024). Glucose and fructose exhibited diurnal variation on one and two dates, respectively (P = .034 and .0028, respectively). These results reveal trends in carbohydrate concentrations and profiles that may help to evaluate the likelihood of equine laminitis outbreaks on bermudagrass.     

高寒草甸优势物种饲用品质对短期放牧的响应

为了解放牧强度对高寒草甸牧草饲用品质的影响,以青藏高原东北边缘高寒草甸为对象,研究了轻度(0.75牦牛单位·hm-2)、中度(1.00牦牛单位·hm-2)和重度(1.25牦牛单位·hm-2)放牧下优势植物珠芽蓼(Polygonum viviparum)和线叶嵩草(Kobresia capillifolia)的全氮、酸性洗涤纤维、中性洗涤纤维含量以及牧草的可吸收营养物质总量和相对饲喂价值等的变化。在放牧末期,中度放牧下牧草的植株高度显著高于其他放牧强度(P0.05)。在整个放牧期,中度放牧下牧草的全氮含量高于其他放牧强度,其中珠芽蓼的全氮含量在放牧末期显著高于重度放牧(P0.05);各放牧强度间植物的酸性和中性洗涤纤维含量在放牧末期无显著差异;中度放牧下牧草的营养价值指数整体呈上升趋势或保持稳定。在青藏高原东北边缘,3年的短期中度放牧利用有利于高寒草甸主要优势物种珠芽蓼和线叶嵩草保持较高而稳定的饲用品质。     

不同降雨年份和放牧方式对荒漠草原初级生产力及营养动态的影响

牧草品质直接体现了草地资源的质量和可利用性。本研究采用野外调查法对不同降雨年份和放牧方式下荒漠草原植物群落的地上净初级生产力(ANPP)、粗蛋白、粗纤维、粗灰分、粗脂肪、钙、磷和无氮浸出物进行了测定和分析。结果表明,1)在干旱的2011年,自由放牧显著降低了群落的ANPP,而在降雨量充足的2012年,休牧60 d的ANPP值最高;2)相比于欠雨年份,降雨量充足的年份生长高峰期ANPP、粗蛋白、粗灰分、钙和磷的含量分别是其的2.67,1.08,1.27,1.26和3.75倍;3)相比其他处理,粗蛋白、磷的含量在休牧60 d含量最高;4)在不同降雨量的两个放牧季节内,随着放牧的进行,粗蛋白、粗脂肪、粗灰分、钙和磷的含量呈现先增加后降低的趋势,均是在7或8月份达到一个峰值,而在植物枯黄期(10月份)值最低,而粗纤维和无氮浸出物的含量在7月份最低,而在植物枯黄期最高。降雨量与荒漠草原植物群落ANPP及植物群落营养季节动态之间存在着密切的关系;休牧60 d为合理的草原利用方式;不同年际间放牧和季节气候变化共同制约了群落营养成分的变化。     

引黄灌区模拟轮牧对春小麦、燕麦和黑麦饲草生产的影响

优质饲草生产是区域草地农业系统稳定的关键,引黄灌区存在季节性饲草亏缺。小麦、燕麦和黑麦等小谷物在引黄灌区有悠久的种植历史,具有生长快、耐刈割和再生能力强的特点,春季直到初夏可以放牧或刈割鲜草,也可调制干草冷季饲用,是潜在的饲草作物。在景泰引黄灌区模拟家畜轮牧小麦、燕麦和黑麦3种小谷物,比较其饲用价值,以期为利用现有作物资源发展动物生产、改革和完善农业系统提供科学依据。结果表明,在景泰引黄灌区模拟家畜轮牧春小麦、燕麦和黑麦3种小谷物,燕麦产草量分别比黑麦和春小麦高38.8%和9.9%,当用作籽实生产时春小麦和燕麦地上部分总生物量分别高于模拟放牧37.5%和35.0%,黑麦差异不显著。轮牧利用的3种小谷物粗蛋白产量显著高于籽实生产。春小麦和黑麦的粗脂肪含量在模拟轮牧下明显高于用于籽实生产,但轮牧下燕麦粗脂肪产量低于籽实生产。轮牧利用后小谷物的粗纤维含量分别下降42.9%,53.0%和21.9%。轮牧后小谷物可溶性碳水化合物含量逐渐增加,而籽实生产的春小麦和黑麦可溶性碳水化合物含量先增加后下降。轮牧下3种小谷物NDF、ADF和纤维素含量低于其用于籽实生产。定量评价,小谷物轮牧利用比籽实生产更具饲用价值,而燕麦的饲用价值高于其他两种作物。     

Grazing and grazing management terminology in southern Africa

In order to avoid misunderstanding arising in discussions and from the literature on grazing management problems in Southern Africa a proposed list of terms and definitions to cater for all grazing situations and concepts is presented. The terms are classified into two groups, those dealing with properties of the vegetation and those dealing with aspects of management. The former group includes veld, fynbos, karoo, grassveid, bushveld, sourveld, swectveld, pastures, leys, permanent pastures, cultivated pastures, introduced pastures, species selective grazing, area selective grazing, grazing capacity, current grazing capacity and potential grazing capacity. Some of these terms are well known to pasture scientists in Southern Africa and their inclusion here is largely to facilitate understanding by overseas readers of the literature from this sub‐continent. Those terms dealing with aspects of management are continuous grazing, rotational grazing, rotational resting, rotational grazing and resting, zero grazing, stocking rate, stocking pressure, stocking density, stocking density index, period of occupation, period of stay, stocking intensity, period of rest and resting intensity. Many of these terms are not in current use in Southern Africa. They nevertheless are related to important concepts in grazing management deserving of greater attention.     

不同精料补饲水平对放牧肉牛生长性能的影响

试验选用健康的三江平原放牧肉牛50头,体重在320 kg左右,随机分成5组,每组10个重复,每个重复1头牛。肉牛放牧采食的同时,试验各组按牛重的0.6%、0.8%、1.0%、1.2%和1.4%每头每天分别饲喂1.9(A组)、2.5(B组)、3.3(C组)、3.8 kg(D组)和4.5 kg(E组)的精料补充料,预试期10 d,试验期60 d。旨在研究冬季放牧条件下,不同精料补饲量对放牧肉牛生长性能的影响。结果表明:(1)随着精料补饲量的增加,肉牛的平均日增重逐渐增加,B组显著高于A组(P<0.05),C、D、E组极显著高于A组和B组(P<0.01);(2)饲料转化率以C组最高,为35.63%,显著高于其他各组(P<0.05),并呈现先增加后降低的规律;(3)经济效益C组最高,C组60 d育肥收入较A组极显著提高176.42%,较B组显著提高80.12%,与C组和D、E组相比略有增加,但差异均不显著(P>0.05)。结果说明,按牛体重的1.0%补饲精料效果最好。     

Area use of two sheep breeds in contrasting summer alpine grazing environments in southern Norway

In Norway, approximately 2 million sheep are released for summer grazing onto highly heterogeneous outer-fields. The crossbred Norwegian White Sheep (NWS) is dominating, whereas the lighter short-tailed gregarious Spælsau (SP) is the second most abundant of the total Norwegian sheep population. We fitted 51 ewes with GPS collars in two contrasting alpine environment, Spekedalen (poor pasture) and Brathøa sauhavnelag (rich pasture), during the summer grazing seasons 2013 and 2014. We modelled breed differences in summer area use and found no significant effect of breed or pasture quality. No breed?* pasture interaction was found. Information of pasture quality and breed characteristics is vital to understand the resource–animal interplay and may prove important for sheep management.     

A comparison of native tallgrass prairie and plains bluestem forage systems for cow-calf production in the southern great plains

The objective of this study was to compare an introduced warm-season perennial grass (plains bluestem, Bothriochloa ischaemum) to native tallgrass prairie for cow-calf production. Three systems were used, two based on tallgrass prairie with two different forms of protein supplementation and one based on plains bluestem as the primary forage. The systems were as follows: 1) native tallgrass prairie with pelleted oilseed meal as the winter protein supplement (native-control); 2) native tallgrass prairie with limited access to wheat pasture as the winter protein supplement (native-wheat); and 3) plains bluestem with limited access to wheat pasture as the protein supplement (bluestem-wheat). Oilseed meal protein supplements were fed twice weekly. Cows grazing wheat pasture were allowed 6 h of grazing twice weekly. Ninety-nine cows per year were used over the 3-yr study. Cows were sired by either Charolais, Gelbvieh, Angus, or Hereford bulls out of commercial Angus-Hereford dams. Calves were sired by Simmental bulls. Calving and weaning rate increased over time but did not differ among systems or breed types. System did not influence the size or body condition score of cows or the performance of calves, but changes in the weight and condition scores of cows were greater on either native system than on the bluestem-wheat system. Cows from Charolais and Gelbvieh bulls were taller (P < 0.05), and heavier (P < 0.05), and weaned heavier (P < 0.05) calves than cows from Angus or Hereford bulls. The weight of cows on the bluestem-wheat system tended to decrease over time, whereas cows grazing on the native systems tended to gain weight over time. The native-control system was the most profitable system based on cow production. If excess hay produced from the bluestem-wheat system was sold as a cash crop, then this system was the most profitable. In general, we conclude that limit-grazing wheat pasture is a viable alternative to oilseed meal as protein supplement for wintering dry cows. Although the bluestem system had 2.5 times the carrying capacity of the native prairie systems, increased productivity was offset by increased production costs. All systems were equal on a cow basis for providing nutrients for the cow-calf production system.     

新疆南疆养羊常用粗饲料体外产气量与有效降解率的相关性分析

研究旨在探索我国肉羊常用粗饲料干物质有效降解率(ED_(IVDMD))的简易评价方法。试验以稻草、甘草秧、芦苇、苜蓿、棉籽壳为试验材料,采用体外产气法与人工瘤胃持续发酵法,在测定产气量(GP)与ED_(IVDMD)的同时,分析了二者之间的相关性及常规营养成分对ED_(IVDMD)的影响,建立了以GP、饲料的常规营养成分预测饲料ED_(IVDMD)的估测模型。结果显示:(1)单一粗饲料原料各个时间点的产气量均与ED_(IVDMD)呈正相关关系(P<0.05)。以相关性最强的预测值GP24为参数,建立预测ED_(IVDMD)的估测模型,其相关系数R2为0.992。(2)饲料的常规营养成分与ED_(IVDMD)的相关性分析结果中:ED_(IVDMD)与中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)均呈显著负相关关系(P<0.05),与粗蛋白(CP)呈正相关关系。建立以ADF、NDF、CP为预测饲料ED_(IVDMD)的一元、多元估测模型,三元估测模型ED_(IVDMD)=-8.935+0.310CP+5.303NDF-6.641ADF(P<0.05,R2=0.999)相关系数最高。(3)建立以常规营养成分结合GP24共同预测ED_(IVDMD)的估测模型中,CP结合GP24预测ED_(IVDMD)的R2最高,为0.994。结论:体外产气法可以代替尼龙袋法估测粗饲料的ED_(IVDMD),从而对肉羊常用粗饲料的降解性能做出快速、合理、有效的评价。     

Factors affecting animal performance during the grazing season in a mountain cattle production system

The factors influencing weight changes during the grazing season of Brown Swiss autumn-calving cows and Brown Swiss and Pirenaica spring-calving cows and their calves were studied over an 8-yr period in Spanish mountain conditions. The data set comprised 552 annual production cycles of cows that calved in two consecutive years. The animals grazed on alpine ranges during the summer and on forest pastures in the spring and autumn. They were housed during the winter and fed at different feeding levels (83 to 117% of their energy requirements) throughout the years of study. Weights were recorded every 3 mo and corrected to account for changes of digestive content and fetal growth, using theoretical relationships. Cow weight gains both on forest pastures and high mountain ranges were higher in autumn- than in spring-calving Brown Swiss cows, and therefore also during the whole grazing season (52.1 vs 7.7 kg, respectively, P < 0.001). Therefore, weight at calving and thereafter was significantly higher in autumn- than in spring-calving cows, which was associated with better reproductive performance (35.5 vs 49.1 d from calving to first ovulation, P < 0.01). In the spring-calving herd, Pirenaica cows had slightly higher gains than Brown Swiss cows during the grazing period (18.5 vs 7.7 kg, P < 0.001), mainly due to their higher gains on forest pastures, but their reproductive performance was similar (44.5 vs 49.1 d from calving to first ovulation, respectively, not statistically significant). Gains were higher in multiparous than in primiparous cows (31.1 vs 14.1 kg, respectively, P < 0.001), especially in the case of Brown Swiss cows, which were younger at first calving. Gains were affected by year of study (P < 0.001) and previous weight changes during the housing period (r = -0.35 and r = -0.21 in autumn- and spring-calving cows respectively, P < 0.001). In the case of autumn-calving cows, performance on pasture was also affected by the stage of pregnancy at housing (r = -0.51, P < 0.001). Growth rates through lactation were higher in autumn- than in spring-born calves (P < 0.001), although the shorter lactation period resulted in lower weight at weaning of the former (P < 0.001). Breed was a significant source of variation in the performance of spring-born calves, weights and gains being higher in Brown Swiss than in Pirenaica calves (P < 0.001).     

不同生长阶段杂交肉牛生产性能的研究

试验分两个生长阶段研究了肉牛的生产性能。4~6月龄阶段选用54头3月龄利木赞×鲁西黄牛杂交牛,7~10月龄选用了18头6月龄利鲁杂交肉牛。试验结果表明,4~6月龄阶段采食高能量日粮的试牛增重效果好,日增重速度最快,显著高于采食低能日粮的肉牛,料重比也变化显著,说明高精粗比例和能量水平提高了试牛的增重,降低了料重比;7~10月龄阶段试牛的体重和日增重符合动物的生长发育规律,速度逐渐加快,平均料重比为6.01∶1。     

不同牧草对五龙鹅生产性能及血液生化指标的影响

为了探讨不同牧草对五龙鹅生产性能和血液生化指标的影响,选取体重均一的3周龄健康五龙鹅仔鹅150只,随机分为对照组、籽粒苋组、苜蓿草组、皇竹草组、苦荬菜组,进行6周的饲养试验,并在8周龄末时进行屠宰,测定血液生化指标。结果表明:苦荬菜组平均日增重最高;牧草组中,籽粒苋组的料重比最低,显著优于苦荬菜组(P<0.05);不同牧草日粮对五龙鹅血清中葡萄糖(Glu)、总胆固醇(TC)、尿酸(UA)、碱性磷酸酶(AKP)和谷丙转氨酶(ALT)均有一定的积极作用。说明3～8周龄五龙鹅饲喂添加籽粒苋的日粮有利于生产性能的发挥。     

Cattle herd vulnerability to rainfall variability: responses to two management scenarios in southern Ethiopia

We examine how the system of grazing management of cattle in savanna rangelands affects the herd response to drought. We have used long-term time series data to evaluate the effects of management on drought-induced cattle mortality using traditional livestock management practices. There was no control of stocking densities, as compared to a government ranch where stocking densities would be adjusted in accordance with available pasture. We tested the responses under two scenarios. Scenario 1: Response of cattle herds to inter-annual rainfall variability (IRV) under a regulated grazing management system; this provides more reliable predictions of cattle population and performance in terms of herd mortality and calving rates than does the communal land use system. Scenario 2: Regardless of the management system, similar trends in cattle populations will be observed in response to IRV. The results of the study showed that fluctuations in cattle numbers, herd mortality and calving rates were highly correlated with IRV, with stronger linear impacts in accordance with scenario 2. In both management systems, cattle herd sizes and calving rates declined during periods of drought, followed by slow recovery. Cattle populations in Borana rangelands in southern Ethiopia did not recover for a period of two decades. We conclude that a management system based on control of stocking densities did not improve herd survival, as compared with traditional drought management strategies. This contradicts common expectations. Increased drought frequencies aggravated cattle mortality and lowered calving rates. The implication of the findings is that regardless of adjusted stocking density, livestock populations in the arid savanna ecosystems of southern Ethiopia remain at risk from climate change.     

Quantitative trait loci for milk production and functional traits in two Danish Cattle breeds

Quantitative trait loci (QTL) in Danish Jersey and Danish Red cattle were independently mapped by least squares regression analysis. For Jersey breed, five grandsire families were genotyped for 186 markers on 16 chromosomes (BTAs). Eight traits analysed were milk yield (MY), fat percentage (FP), protein percentage (PP), clinical mastitis (CM), somatic cell score (SCS), maternal stillbirth, maternal calf size (MCS) and maternal calving difficulty. For Red breed, nine grandsire families were genotyped for 166 markers on 18 BTAs. Six traits analysed were MY, FP, PP, CM, SCS and female fertility. Nine and five QTL were detected in Jersey and Red breed, respectively, in across family tests. In Jersey breed, the results indicate QTL for CM and MCS on BTA 3. Additionally, there is an indication of QTL for MCS and FP on BTA 1 and a tentative evidence for a QTL for MY on BTA 26. There is a high risk of detected QTL being false positives. The detected QTL in Jersey breed indicate interesting results from a breeding perspective, but a practical application should await genome-wide association studies.