绿洲区滴灌施磷对苜蓿地肥力和磷素利用率的影响

为探讨绿洲区滴灌施磷对苜蓿磷素利用效率的影响及其土壤肥力变化规律,在石河子绿洲区滴灌苜蓿田设不同的施磷处理,即1次性施180 kg·hm^-2磷肥（L₁）、1次性施360 kg·hm^-2磷肥（H₁）、均分3次施180 kg·hm^-2磷肥（L₂）、均分3次施360 kg·hm^-2磷肥（H₂）及不施肥（CK）,对各处理下苜蓿田土壤肥力和磷素利用效率进行测定和分析。结果表明,较CK相比,L₂处理可显著提高耕作层平均有机质含量（P<0.05）,H₁和H₂处理可显著提高耕作层平均全磷含量（P<0.05）。各处理均可显著提高耕作层平均速效磷含量（P<0.05）。各处理对平均碱解氮含量及pH值无显著影响。‘新牧2号’苜蓿（Medicago sativa ‘Xingmu No.2’）磷素利用效率最高的为L₁和L₂处理（F=17.02）,‘三得利’（Medicago sativa ‘Sanditi’）为L₂处理（F=14.33）。因此,建议绿洲区苜蓿栽培滴灌施磷的最佳模式为均分3次施用180 kg·hm^-2磷肥。     

5个苇状羊茅品种在川中丘陵地区生产性能综合评价

在川中丘陵地区遂宁市河沙镇和天保镇,对5个苇状羊茅（Festuca arundinace Schreb.）品种进行牧草生产性能的比较研究,旨在筛选出适宜在该区种植的品种。结果表明,‘科瑞’在两个试点的生长速度和干草总产量均最高,分别为0.564 cm·d^-1和8 842 kg·hm^-2,显著高于其它品种（P<0.05）,其次为‘金刚’和‘马丁’。粗蛋白和可溶性碳水化合物产量均以‘科瑞’最高,分别为1 345 kg·hm^-2和887 kg·hm^-2,均显著高于其它品种（P<0.05）,其次为‘美食家’和‘金刚’;中性洗涤纤维和酸性洗涤纤维产量均以‘美食家’和‘科瑞’最低,二者无显著性差异。综上所述,‘科瑞’、‘美食家’和‘金刚’的干草产量较高,营养品质较好,在川中丘陵区具有较好的推广价值。     

西北旱区灌溉方式对苜蓿生长及水分利用效率的影响

为探讨不同灌溉方式对紫花苜蓿(Medicago sativa)生长、水分利用效率及产量的影响,通过田间试验研究了地下滴灌(SDI)、畦灌(BI)、喷灌(SI)和不灌溉处理(CK)4种灌溉方式下苜蓿生长的变化。结果表明:各处理间,SDI的土壤含水率在试验期间最高,且SDI的苜蓿株高、分枝数、单株叶面积及单株干重均显著高于BI,SI和CK;SDI两茬的产量分别为4815.87和4300.41kg·hm^-2,与BI,SI和CK相比,第2茬分别提高了10.56%,14.92%和95.26%,第3茬分别提高了13.64%,23.60%和120.85%,均达到显著水平(P<0.05);SDI两茬的水分利用效率分别为2.66和2.50kg·m^-3,较BI和SI处理,第2茬分别提高了17.70%和21.46%,第3茬提高了20.77%和34.41%,均达到显著水平(P<0.05)。因此,从苜蓿生长、产量及水分利用效率角度考虑,地下滴灌是西北旱区最为适宜的灌溉方式。     

不同刈割时期与刈割高度对苜蓿品质的影响

为研究不同刈割时期与刈割高度对苜蓿品质的影响,开展不同刈割时期和刈割高度对紫花苜蓿干草质量影响的研究,以1：1比例种植的金皇后（Golden Empress）与三得利（Sanditi）紫花苜蓿为试验材料,于不同生育时期与刈割高度进行干草产量和营养成分测定。结果表明：与初花期收获的苜蓿相比,苜蓿生长高度80 cm（现蕾期）左右时刈割,鲜草产量和干草产量比初花期分别高2510.4 kg·hm^-2和807.3 kg·hm^-2,粗蛋白（Crude Protein,CP）量和相对饲用价值（Relative Feed Value,RFV）值分别高2.45%、1.35,差异极显著（P<0.01）。综合得出,在赤峰地区,以生长高度为刈割标准,株高在80 cm左右时刈割可以得到质量兼优的苜蓿草。     

燕麦品种在甘肃陇西县二阴山区的引种比较研究

在陇西二阴山区,对13种燕麦(Avena sativa)的农艺性状及营养价值进行比较研究,结果表明:选用的13种燕麦品种种子均能饱满成熟,其中,株高低于100 cm有5种;101～110 cm有5种;111 cm以上有3种。‘青海甜燕麦’(16100 kg·hm^-2)和‘冀引1号’(15600 kg·hm^-2)的干草产量显著高于其他品种(P<0.01),‘巴彦3号’(4500 kg·hm^-2)干草产量最低。成熟期‘白燕2号’、‘冀引1号’NDF高于其他品种。‘青永久307’ADF最高,‘黄燕麦’ADF最低。‘TCO燕麦’CP最高,‘青引1号’最低。综合分析表明,‘青海甜燕麦’、‘青引1号’、‘欧洲316’、‘青永久307’是甘肃陇西县二阴山区建植燕麦草地的首选品种。     

紫花苜蓿产草量一般配合力分析及其遗传参数估算

为培育高产苜蓿(Medicago sativa L.)新品种,以110个苜蓿高产单株的半同胞后代为材料,研究其第1茬、第2茬、第3茬、第4茬及全年产草量一般配合力,并在此基础上进行聚类分析。结果表明:产草量一般配合力较高的植株共22株,一般配合力中等的植株共48株,一般配合力较低的植株共40株;淘汰40株产量一般配合力较低的单株,收到70株产量一般配合力较高的单株相互杂交的种子,完成了一次轮回选择。苜蓿第1茬、第2茬、第3茬、第4茬产草量广义遗传力分别为H²=34.95%,H²=50.42%,H²=29.52%,H²=1.9%;苜蓿全年产草量的广义遗传力为H²=25.58%。     

紫花苜蓿不同茬次及年际间生产性能的动态规律

在海河平原区,先后选取22个、14个苜蓿（Medicago Stiva）品种,雨养条件下通过7年和4年的试验结果表明：不同茬次干草产量表现为逐渐降低的趋势,每年刈割4次：第1茬 > 第2、3茬 > 第4茬;刈割5次：第1茬 > 第2茬 > 第4茬 > 第3茬 > 第5茬;前2茬苜蓿年平均干草产量均占全年总产量的52%以上,第3茬干草占全年总产量的25%以下;随茬次的增加,株高总体上表现为逐渐下降的趋势;第2茬草的叶茎比极显著高于第3、4茬（P<0.01）,第4茬草的叶茎比最低;粗蛋白含量为第2、3茬>第1、4茬,并且差异极显著（P<0.01）。苜蓿在海河平原区存在明显的“夏眠”现象,造成了光、温、水资源的浪费。7年连续测定结果表明,在海河平原区紫花苜蓿适宜的利用年限为4~5年。     

施磷对滴灌苜蓿干草产量及磷素含量的影响

为探讨不同施磷量对滴灌苜蓿干草产量、吸磷量及苜蓿磷素利用效率的影响,明确不同磷素水平下土壤全磷和速效磷的含量分布特征。试验设4种施磷梯度,分别为施P₂O₅ 0 kg·hm^-2(CK)、50 kg·hm^-2(P₁)、100 kg·hm^-2(P₂)、150 kg·hm^-2(P₃),采用滴灌水肥一体化施肥方式,平均分4次分别在返青后的分枝期、第1茬、第2茬、第3茬刈割后3~5 d施入。结果表明,各茬次苜蓿植株叶片、茎秆磷含量在P₂处理下达到最大值,其中叶片磷含量数值分别为0.223%,0.275%,0.292%和0.218%;茎秆磷含量数值分别为0.202%,0.223%,0.201%和0.146%。苜蓿叶片磷含量大于茎秆磷含量。滴灌苜蓿植株的干草产量、吸磷量随着施磷量的增加呈先增加后降低的趋势,在第1茬P₂处理达到最大值,数值分别为6.54 t·hm^-2和13.78 kg·hm^-2。土壤全磷含量、速效磷含量随着施磷量的增加呈逐渐增大的趋势,且各施磷处理显著大于未施磷处理(P<0.05),滴灌苜蓿总干草产量在P₂处理条件下达到最大,达21.24 t·hm^-2。苜蓿的磷素利用效率为随施磷量的增加呈逐渐降低的趋势,P₁处理苜蓿的磷素利用效率在第1茬达到最大值为28.37%。滴灌苜蓿植株吸磷量与干草产量呈极显著正相关(P<0.01)。当施P₂O₅为100 kg·hm^-2(P₂)时,能够有效促进苜蓿根系对土壤速效磷的吸收,提高苜蓿磷素利用效率,进而提高滴灌苜蓿干草产量。     

闽牧3号圆叶决明的选育研究

为提高草产量及适口性,2002年由福建省农业科学院农业生态研究所利用⁶⁰Coγ射线辐射闽引圆叶决明（Chamaecrista rotundifolia ‘Minyin’,CPI86134）种子,经多代筛选选育出闽牧3号圆叶决明（Chamaecrista rotundifolia ‘Minmu No.3’）,并于2011年通过福建省品种认定委员会认定。2005-2010年进行品种比较试验、区域试验和生产试验,结果表明：闽牧3号圆叶决明平均种子产量260.9 kg·hm^-2,比对照增产7.7%,但差异不显著;初花期植株粗蛋白含量为18.84%;平均干草产量11110.4 kg·hm^-2,比对照闽引圆叶决明增产22.05%,差异极显著（P<0.01）。因此,闽牧3号圆叶决明适用于加工草粉饲料。     

氮磷互作对不同茬次滴灌苜蓿生产性能及营养品质的影响

为探讨滴灌条件下不同氮磷互作模式对绿洲区滴灌苜蓿生产性能及营养品质的影响,本试验设置施N 105 (N₁)和210 kg·hm^-2(N₂)2种梯度,施P₂O₅ 0 (CK)、50 (P₁)、100 (P₂)和150 kg·hm^-2(P₃)4种施磷梯度,交互配施共8个处理(N₁P₀、N₁P₁、N₁P₂、N₁P₃、N₂P₀、N₂P₁、N₂P₂、N₂P₃),采用随机区组设计,对滴灌苜蓿各生长性状、干草产量及营养品质进行测定。结果表明:N₁条件下,前3茬中,苜蓿的株高、茎粗、生长速度、干草产量和粗蛋白质含量均表现为P₂处理大于其他处理;N₂条件下,苜蓿的株高、茎粗、生长速度、干草产量和粗蛋白质含量均表现为P₁处理大于其他处理;N₁、N₂条件下,各茬次苜蓿叶片、茎秆的酸性洗涤纤维、中性洗涤纤维含量均表现为P₂处理小于其他处理。P₀、P₂和P₃条件下,前3茬中,苜蓿的株高、茎粗、生长速度、干草产量和粗蛋白质含量均表现为N₁处理大于N₂处理;相同施磷条件下,苜蓿叶片、茎秆的酸性洗涤纤维、中性洗涤纤维含量均表现为N₁处理小于N₂处理。通过对苜蓿各生长性状指标与干草产量灰色关联度分析表明,生长速度和茎粗对苜蓿干草产量的贡献率较大,株高和茎叶比对苜蓿干草产量的贡献率较小。通过模糊相似优先比评价表明,不同氮磷处理下滴灌苜蓿各茬次的较优施肥模式为N₁P₂处理,此处理下,苜蓿能够获得较高干草产量(25103.19 kg·hm^-2)、高蛋白含量(叶:23.60%~26.47%、茎:10.57%~11.76%)、低酸性洗涤纤维含量(叶:13.28%~17.41%、茎:38.63%~47.21%)和低中性洗涤纤维含量(叶:18.18%~22.93%、茎:49.53%~59.83%)。在新疆绿洲区,施氮(N)105 kg·hm^-2、磷(P₂O₅)100 kg·hm^-2有利于促进滴灌苜蓿干草产量的形成及营养品质的提高。     

西藏山南地区6种野生牧草营养价值评定

选用6只装有瘘管的西藏澎波半细毛羊,用尼龙袋法对采于西藏山南地区的6种野生禾本科牧草的营养成分含量及其在绵羊瘤胃内的降解特性进行了测定,分析评价其营养利用价值。结果表明:6种牧草的干物质(DM)、粗蛋白质(CP)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的瘤胃降解消失率和降解特征存在很大差异;随着样品在瘤胃内停留时间的延长,降解消失率也随之提高,在3-48 h时,增加的幅度较快,48h后,增加的速度放缓;到72 h,狗尾草(Setaria viridis (L.) Beauv.)的降解消失率最大,其DM、CP和NDF的降解消失率均超过60%;蛋白质较高、纤维含量较低的狗尾草和白草(Pennisetum centrasiaticum Tzvel.),其DM、CP、NDF和ADF的快速降解部分、慢速降解部分及有效降解率均比其他4种牧草高;而白茅(Imperata cylindrical (L.) Beauv.)和沙生针茅(Stipaplareosa P.Smirn.)营养成分表现出比其他4种牧草差的降解特征。综合考虑6种牧草所含营养成分及其在绵羊体内的降解能力,狗尾草和白草利用价值较高,白茅和沙生针茅利用价值较低。     

A tensilmeter for the measurement of the tensile strength of grass leaf blades 1

The design and construction of a simple and inexpensive tensilimeter for measuring the tensile properties of grass leaves is described. The instrument was found to give reliable results and was used to estimate the variation in the breaking force and breaking tension along the length of leaf blades of six grass species. While the pattern varies amongst the grasses tested there was a general tendency for both leaf strength and leaf tissue strength to increase from the lip to the base of the blade of all six species.     

Determination of physical characteristics,chemical composition and digestion coefficients of treated lemon pulp with Saccharomyces cerevisiae in goat diet

The aim of this study was to evaluate the effects of processing of lemon pulp with Saccharomyces cerevisiae on physical properties, chemical composition, digestion coefficients and blood parameters. Eight adult male Raeini goats were used in a 28‐day period. The experimental design was a completely randomised design with two treatments and four replicates. The first 21 days were for adaptation, and the last 7 days were for collecting samples. The animals were housed in individual metabolic cages equipped with a urine–faeces separator and were fed with diet containing alfalfa hay (60%) and lemon pulp (40%) at the maintenance level. Collected data were subjected to analysis of completely randomised design. With diet containing processed lemon pulp, functional specific gravity, bulk density, soluble dry matter, percentage of crude protein, neutral detergent fibre (NDF), acid detergent fibre and crude ash were significantly increased and water‐holding capacity, insoluble dry matter, insoluble ash percentage of dry matter, organic matter, crude fat, non‐fibrous carbohydrates and nitrogen‐free extract were significantly decreased (p < 0.05). Digestion coefficient of organic matter in dry matter and metabolisable energy were also decreased in treated lemon pulp (p < 0.05). Compared with untreated lemon pulp, digestibility of crude protein and NDF was higher (p < 0.05), but digestibility of crude fat was lower (p < 0.05). In general, processing of lemon pulp with S. cerevisiae improved the physical characteristics and increased the percentage of crude protein and the digestion coefficients of protein and NDF.     

Enzymatic characteristics of crude feruloyl and acetyl esterases of rumen fungus Neocallimastix sp. YAK11 isolated from yak (Bos grunniens)

Rumen fungus Neocallimastix sp. YAK11 was isolated from yak (Bos grunniens), and three consecutive 10‐day pure cultures were anaerobically performed at 39 °C in 20‐ml Hungate’s tubes to explore ferulic acid esterase (FAE) and acetyl esterase (AE) activity profiles of the fungus grown on whole hay fraction of Chinese wildrye grass (Leymus chinensis) (WHO_cw, n = 4) and its neutral detergent fibre fraction (NDF_cw, n = 4), respectively. An aliquot of 0.7‐ml culture was sampled daily using a sterile syringe, and 0.7‐ml fresh medium was immediately added to the tubes to compensate for the withdrawn samples. Peak esterase activity occurred for FAE on day 5 (p < 0.001) and for AE on day 6 (p < 0.001). The mean activities of FAE and AE in WHO_cw were 2.07 and 1.29 times of those in NDF_cw (p < 0.001). Both FAE and AE activities were positively correlated with xylanase (r > 0.65, p < 0.001) and carboxymethyl cellulase (r > 0.57, p < 0.001) activities. Total volatile fatty acid concentration was positively correlated with enzyme activities of AE (r > 0.87, p < 0.001), FAE (r > 0.82, p < 0.001) and xylanase (r > 0.56, p < 0.001). Crude enzyme solution was harvested for the fungus grown on WHO_cw, and the pH optimum of FAE activity was 8.0 while the optimum for AE was 9.0. Both FAE and AE had a broad pH stability range. The optimal temperatures for FAE and AE activity were 40 and 50 °C. The Michaelis constant (K_m) and maximum velocity (V_max) for FAE against methyl ferulate at pH 6.0 and 39 °C were 0.078 mm and 2.93 mU, respectively. The K_m and V_max for AE against p‐nitrophenyl acetate at pH 7.0 and 39 °C were 2.73 mm and 666.67 mU, respectively. Both FAE and AE may have prospective advantages for the enzymatic degradation of roughages in ruminant animals.     

Effect of neutral detergent soluble fibre on digestion, intestinal microbiota and performance in twenty five day old weaned rabbits

The effect of neutral detergent soluble fibre (NDSF) level on digestibility, fermentation traits, intestinal microbiota and performance was studied in weaned rabbits. A control diet (DA) containing 103 g NDSF/kg DM included dehydrated alfalfa as the main source of fibre. Another diet (B-AP) was formulated by replacing half of the dehydrated alfalfa with a mixture of beet and apple pulp resulting in 131 g NDSF/kg DM. A third diet (OH) was obtained by substituting half of the dehydrated alfalfa with a mix of oat hulls and a soybean protein concentrate and contained 79 g NDSF/kg DM. All diets contained similar levels of total fibre (NDSF + neutral detergent fibre), starch and protein (446, 208, and 199 g/kg DM, respectively). Forty-two rabbits (14/diet) weaned at 25 days were used to determine faecal digestibility from 32 to 35 days of age. This group, plus another nine rabbits/diet (23/diet), were used to determine weight of stomach and caecum and their contents, caecal fermentation traits and similarity rate (SR) of intestinal microbiota. Another 105 and 245 weaned rabbits were used to determine growth traits and mortality, respectively. From 25 to 39 days of age, rabbits were fed the experimental diets and from 39 to 60 days they were fed a commercial diet, including robenidine hydrochloride in all diets. Drinking water was supplemented with apramicine sulfate and tylosine tartrate throughout the experimental period. Faecal and energy digestibility increased linearly by 8% and NDF digestibility by 43% between extreme diets with NDSF inclusion (P < 0.001). Weight of total gastrointestinal tract decreased linearly and quadratically with NDSF reduction (P = 0.008 and P = 0.089, respectively). Stomach pH decreased linearly with increasing levels of NDSF (P ≤ 0.041). Weight of caecal contents increased linearly between animals fed OH and B-AP diets (P < 0.001). Level of inclusion of NDSF had no effect (P ≥ 0.12) on pH, VFA concentration and VFA molar proportions in caecal contents. Treatments appeared to influence the SR of caecal microbiota but a lesser effect was observed on ileal microbiota. Post weaning feed efficiency (25–39 days) increased linearly (P < 0.001) with NDSF inclusion by 10% between extreme diets, and by 3% in the whole fattening period (P = 0.027). Average feed intake during the post weaning (25–39 days) and the whole fattening period increased with NDSF reduction (P ≤ 0.079). No effect of NDSF was detected on average daily gain (P ≥ 0.15). Mortality decreased linearly with increasing levels of NDSF in the post weaning and in the whole fattening period (P = 0.086 and 0.016, respectively).     

反刍动物日粮物理有效中性洗涤纤维的研究进展

饲料纤维在反刍动物日粮中不仅具有化学成分的重要性,且纤维的物理性状(颗粒大小)还能够影响咀嚼活动、瘤胃发酵、乳脂肪含量及机体健康状况。作者就表征纤维的化学和物理性状的指标——物理有效中性洗涤纤维的定义、内涵、计算方法及对反刍动物进食行为、瘤胃发酵、营养物质消化率和泌乳性能等方面的营养调控功能进行了综述。     

日粮ADF水平对肉兔胃肠道发育、免疫及屠宰性能的影响

选用60只体重相近的2月龄新西兰肉兔,随机分为5组,分别饲喂5种酸性洗涤纤维(ADF)水平(13%、16%、19%、22%和25%)的日粮,旨在探讨我国家兔适宜的ADF需要量。结果表明:随日粮ADF水平升高,胃占活重比重先增加后降低(P<0.05),小肠占活重比重各处理间差异不显著(P>0.05),盲肠占活重比重显著增加(P<0.05)。日粮ADF水平对试兔胸腺指数日粮影响显著(P<0.05),对脾脏指数影响不显著(P>0.05)。随日粮ADF水平提高,试兔心脏和肾脏相对重量先上升后下降(P<0.05),肝脏相对重量逐渐下降(P<0.05);试兔全净膛和半净膛屠宰率呈先上升后下降的趋势(P>0.05)。由此认为,2～3月龄肉兔适宜的ADF水平为16%～19%。     

羊草和苜蓿草产品营养物质瘤胃降解特性的研究

运用尼龙袋法,对不同加工方式形成的羊草和苜蓿草产品(草粉、草颗粒)进行了瘤胃降解粗蛋白质、中性洗涤纤维的评定,结果表明:(1)6～12h苜蓿草粉的粗蛋白质消失率显著高于吉生羊草草粉、野生羊草草粉、吉生羊草颗粒(p＜0.05).(2)12h、24h、72h苜蓿草粉中性洗涤纤维的消失率显著高于吉生羊草颗粒、吉生羊草草粉、野生羊草草粉(p＜0.05).(3)吉生羊草颗粒中性洗涤纤维的消失率与动态降解率要高于吉生羊草草粉、野生羊草草粉,吉生羊草草粉的蛋白质和中性洗涤纤维的消失率和动态降解率要高于野生羊草.     

Vegetation-type effects on performance and meat quality of growing Engadine and Valaisian Black Nose sheep grazing alpine pastures

Lambs of two Swiss mountain breeds, Engadine Sheep (ES; n=55) and Valaisian Black Nose Sheep (VS; n=55), were fattened in 2010 and 2011 on one lowland and three alpine pastures. Groups of six to seven lambs per breed were allocated to pastures of a size allowing ad libitum intake on the following four vegetation types: (i) species-poor and nutrient-rich lowland (400 m a.s.l.) ryegrass–clover ley on flat terrain (‘lowland-rich’); (ii) alpine, species-rich and nutrient-rich vegetation type on a flat terrain (1950 m; ‘alpine-rich’); (iii) alpine, species-rich vegetation type, moderate in nutrients on steep terrain (2150 m; ‘alpine-moderate’); and (iv) alpine, species-rich and nutrient-poor vegetation type on steep terrain (2150 m; ‘alpine-poor’). Lambs were slaughtered after 9 weeks of grazing in a commercial slaughterhouse. Carcasses were subjected to the Swiss CH-TAX classification grid. Meat quality was analysed on the Musculus longissimus dorsi (LD) in the segment of Musculus longissimus lumborum. Forage quality varied among vegetation types as anticipated. Across all sites, ES were superior (P<0.001) to VS in dressing percentage (43.9 vs. 38.4), carcass weight (18.4 vs. 16.4 kg), meat conformation and fat cover scores, even though daily gains had been lower (105 vs. 122 g/d; P<0.05). Meat of ES contained more dry matter, protein, total ash (P<0.001) and fat (P<0.05). Their meat was darker and more intensive red, had lower cooking losses (23.0 vs. 25.1%) but was less tender (65.6 vs. 58.1 N) compared to VS (P<0.001). Vegetation types offering good quality forage (lowland-rich and alpine-rich) enhanced average daily gains, dressing percentage, meat conformation and fat cover scores (mostly P<0.05 against alpine-moderate and -poor). Similarly, a higher vegetation quality promoted a higher intramuscular fat and lower cooking losses. Meat from lowland-rich was darkest and had the lowest shear force (P<0.05). Almost no breed×site interactions occurred in growth performance as well as carcass and meat quality. It was therefore concluded that both breeds are similarly well adapted to the extensive pasture production system in alpine regions. Still, ES seem to be the more efficient one of the two sheep breeds. The results also indicate that growth performance and meat quality clearly vary between vegetation types in animals grazing alpine pastures.     

Selenium supplementation improves nutrient intake and digestibility,and mitigates CH4 emissions from sheep grazed on the mixed pasture of alfalfa and tall fescue

Low selenium (Se) in soil and forage can adversely affect on the quality of animal-derived foods, and hence on human health. Lambs grazed on mixed pastures of alfalfa (Medicago sativa) and tall fescue (Festuca arundinacea) were supplemented with five levels of Se [0, 3, 6, 9 and 12 µg/kg body weight (BW)]. The intake of dry matter (DM) and organic matter (OM) varied with the level of Se supplementation, with a peak at 6 µg Se per kg BW (p ≤ 0.05). Gross energy (GE) intake, digestive energy (DE) intake and metabolic energy (ME) intake were higher at 6 µg Se per kg BW than at other Se levels (p < 0.01); in addition, methane energy (CH₄-E) output was lower at 6 µg Se per kg BW. Supplementation with Se significantly increased nitrogen (N) intake, faecal N and urine N, for which the peak values were 20.2 g N/, 5.62 g N/day and 7.92 g N/day, respectively, at 6 µg Se per kg BW. Se intake, blood Se, faecal Se, urine Se and retained Se were negatively correlated with forage crude protein (CP) content (p < 0.001) but were positively correlated with the content of neutral detergent fibre (NDF) (p < 0.001) and acid detergent fibre (ADF) (p < 0.001). Thus, we recommend the addition of 6 µg Se per kg BW to sheep grazed on pastures in regions with low soil Se.