No easy solution for the fractionation of faecal nitrogen in captive wild herbivores: results of a pilot study

Faecal nitrogen (FN) concentration is used as a marker for habitat quality and digestive efficiency in free‐ranging herbivores. In herbivores, FN can be separated into undigested plant N (analysed as the N concentration of the neutral detergent residue) and metabolic faecal N (MFN). It has been suggested that by differential analysis of the faecal fibre‐bound N, the MFN fraction can be further split into a bacterial N and an endogenous N fraction [Hesta et al., Br. J. Nutr. 90 (2003) 1007]. We applied these methods to 96 faecal samples of 48 mammalian herbivore species from zoos. Species were grouped into coprophageous and non‐coprophageous hindgut fermenters and ruminating and non‐ruminating foregut fermenters. Diet was not controlled. The FN decreased with body mass, possibly reflecting higher proportions of concentrates in diets of smaller animals. The proportion of MFN increased with FN, indicating that higher quality food might enhance the gastrointestinal bacterial flora. The only outlier to this pattern was the lesser panda (Ailurus fulgens), confirming the low relevance of fermentative digestion in this herbivorous ‘carnivore’. No relevant differences between the four digestion types were noted. The proportion of endogenous faecal N (32–80% of FN) was always higher than that of bacterial faecal N (7–30%), which contradicts basal understanding of herbivore digestive physiology. Thus, the method of Hesta et al. (2003) does not appear applicable to herbivores. While the results do not exclude the possibility that detailed differences might occur between digestion types, they indicate a high degree of similarity between herbivores that rely on bacterial fermentation, regardless of their digestion type, with respect to metabolic faecal losses.     

SILVER IMPREGNATION IN SITU

In evaluating radiographs of the limb joints and head, students encounter difficulty where superimposition occurs. By replacing calcium with silver salts in the bone, enhanced radiopacity can be produced. In this study, silver impregnation was used to increase the radiopacity of individual carpal and tarsal bones, selected bones of the skull and the sinuses, and guttural pouch of the horse. This provides an interpretation aid for teaching radiographic anatomy of these regions.     

氮磷肥对3种牧草的生长效应和氮磷吸收的影响

采用田间试验,单因素随机区组排列,以豆科牧草柱花草和禾本科牧草扭黄茅和孔颖草为试验材料,研究适量氮磷肥的施用对3种牧草旺盛期生长及土壤氮磷吸收的影响和效果。试验结果表明,与未施氮磷肥比较,氮磷的施用有利柱花草、扭黄茅和孔颖草旺盛期(7-9月)的生长,3种牧草物候期有所延迟,可以提高3种牧草旺盛期绝对生长量,显著增加了孔颖草总生物量和氮吸收量(P<0.05)。与未施氮肥对比,施氮(施纯氮120 kg·hm^-2)有利柱花草和孔颖草对氮的吸收,显著提高柱花草含氮量和孔颖草氮的吸收量(P<0.05),促进柱花草和孔颖草的生长,提高柱花草和孔颖草地上部和地下部生物量,提高扭黄茅地上部的生长量和生物量。与未施磷肥对比,施磷(施纯磷75 kg·hm^-2)显著提高孔颖草氮的吸收量(P<0.05)。本研究为3种牧草和其他牧草氮磷的施用提供理论依据,即:适量的氮磷施用有利3种牧草产量的提高。     

Effects of feeding and animal performance on nitrogen, phosphorus and potassium excretion by Holstein cows

Thirty‐four Holstein dry cows and 16 lactating cows were used in balance trials to identify the effects of feeding and animal performance on nitrogen (N), phosphorus (P) and potassium (K) excretion by dairy cows, and to develop prediction models for these excreta. Orchard grass silage, corn silage, alfalfa silage or timothy hay were offered to dry cows. Orchard grass silage or alfalfa silage, and concentrates were offered to lactating cows. In the statistical analysis, the independent variables were bodyweight (kg), dry matter (DM) intake (kg/day), milk yield (for lactating cows only, kg/day), water intake (free water plus water in feed, kg/day), intake (g/day) of N, P and K and dietary contents (% of DM) of crude protein, P and K. The dependent variables were N, P and K excretion (g/day) in feces and urine. In both dry and lactating cows, intake of N, P and K had large effects on corresponding excretion. The results indicated that a decrease in the intake of N, P and K could decrease the corresponding excretion. Further research by path analysis showed that K intake positively affected urinary N excretion in dry cows indirectly, through water intake and urine volume.     

绵羊宿营法清除天然植被对土壤和植物的影响

研究绵羊宿营法通过践踏和粪尿对土壤和对天然植被和人工草地的影响。结果表明,绵羊啃食和践踏对植被地上部分损坏严重,8羊夜后草本植物被全部清除,但对土壤容重、紧实度和通气性无显著影响。新鲜粪尿入土后,氨态氮和亚硝态氮浓度迅速上升(最高值分别达377mg·kg^-1和56.1mg·kg^-1),对植物产生毒害作用。单纯尿处理土壤氨态氮和亚硝态氮浓度分别达139mg·kg^-1和28.1mg·kg^-1,显著高于单一粪处理和对照。无毛丑柳叶片粗蛋白质含量显著高于对照(P<0.01)。调查结果表明,羊奶果和黄花香发芽枝条数在试验前后变化不大,但宿营后的无毛丑柳枝条数显著少于处理前。宿营处理的产草量明显高于践踏处理。     

苏丹草种子半透层定位与透性研究

通过硝酸镧示踪、透射电镜观测和X射线能量色散分析等技术,对苏丹草种子半透层的位置和透性进行了研究.从解剖学角度证明了苏丹草种子存在半透层,该组织位于糊粉层内侧紧靠未分化细胞处,对水分通透性好,但阻挡电解质渗出和镧盐渗入.老化对种子膜系统有一定损伤,但对半透层并无显著影响.     

草粮轮作与农田生态平衡——兼论 Ladino 白三叶的生态经济效益

利用无性繁殖法定植Ｌａｄｉｎｏ白三叶（Ｔｒｉｆｏｉｕｍｒｅｐｅｎｓ）和雅安逸生白三叶（Ｔ．ｒｅｐｅｎｓ），地上部生物量前者比后者表现出极显著差异；地下部生物量和贮氮量表现为显著差异。后作玉米产量，Ｌａｄｉｎｏ白三叶地为６．２９ｔ／ｈａ大于雅安逸生白三叶地（６．１５ｔ／ｈａ）；农田生态系统里前者表现为正氮平衡，后者表现为负氮平衡，前者土壤固相、液相和气相比为１∶０．５∶０．２５明显优于后者；前者Ｃ／Ｎ比适中，后者Ｃ／Ｎ过窄，其抗性雅安逸生白三叶低于Ｌａｄｉｎｏ白三叶。三种种子直播的豆科牧草的生态经济特性表现为南苜蓿（Ｍｅｄｉｃａｇｏｈｉｓｐｅｄａ）大于苕子（Ｖｉｃｉａｃｏｒａｃｃａ），紫云英（Ａｓｔｒａｇａｌｕｓｓｉｎｉｃｕｓ）则介于两者之间。草粮轮作周期证明，Ｌａｄｉｎｏ白三叶和南苜蓿以及苕子是无性繁殖和有性繁殖的最佳材料，值得广泛推广利用。     

The influence of nitrate and ammonium forms of nitrogen fertilizer on the growth and osmoregulation of digitaria eriantha and Chloris gayana grown under saline conditions

Abstract

Digltaria eriantha and Chloris gayana were grown under controlled conditions for three months and were treated with a nutrient solution containing 150 mMol NaCl and the following nitrogen sources: 25 or 200 mg/l NH₄ ⁺‐N or NO₃ ^?‐N or no nitrogen. The application of nitrogen was found to stimulate growth, i.e. leaf area and dry mass in both grasses, with a greatest growth response to both NH₄ ⁺—N treatments in D. eriantha, and NH₄ ⁺‐N and NO₃ ^?—N treatments in C. gayana. Proline accumulated in both grasses, but this accumulation followed different trends in the two grasses. Soluble sugars (non‐structural) accumulated in the above ground component in D. eriantha, while in C. gayana soluble sugars accumulated predominantly in the roots, possibly as osmotica, or for storage and may thus have been available for regrowth.     

饲粮亚油酸水平对育成期蓝狐生长性能、营养物质消化率及氮代谢的影响

本试验旨在研究饲粮亚油酸水平对育成期蓝狐生长性能、营养物质消化率及氮代谢的影响。选取(90±5)日龄、体重相近的健康雄性蓝狐60只,随机分成6组,每组10个重复,每个重复1只蓝狐。6组蓝狐分别饲喂亚油酸水平为0.11%(Ⅰ组)、0.52%(Ⅱ组)、0.92%(Ⅲ组)、1.33%(Ⅳ组)、2.14%(Ⅴ组)和3.36%(Ⅵ组)的试验饲粮。预试期7 d,正试期63 d。结果表明:1)饲粮亚油酸水平极显著影响育成期蓝狐的平均日增重和料重比(P0.01),对干物质采食量无显著影响(P0.05)。随饲粮亚油酸水平由0.92%升高到3.36%,平均日增重逐渐升高,料重比逐渐降低,但上述指标Ⅳ和Ⅴ组间差异不显著(P0.05)。2)饲粮亚油酸水平极显著影响育成期蓝狐的脂肪、碳水化合物及干物质消化率(P0.01),对蛋白质消化率无显著影响(P0.05)。脂肪和碳水化合物消化率均以Ⅵ组最高,干物质消化率以Ⅴ组最高,但上述3个指标在Ⅳ和Ⅴ组间均无显著差异(P0.05)。3)饲粮亚油酸水平显著或极显著影响粪氮、尿氮和蛋白质生物学价值(P0.01或P0.05),对食入氮、氮沉积和净蛋白质利用率无显著影响(P0.05)。粪氮以Ⅵ组最高,与Ⅱ、Ⅳ和Ⅴ组差异不显著(P0.05)。尿氮以Ⅱ组最高,与Ⅲ、Ⅳ和Ⅴ组差异不显著(P0.05)。Ⅵ组蛋白质生物学价值最高,显著高于Ⅱ组(P0.05),与其他组差异不显著(P0.05)。从降低环境污染以及保证育成期蓝狐生长性能的角度综合考虑,饲粮亚油酸水平为2.14%较适宜。     

离子载体在反刍动物生产上的应用研究进展

离子载体自1968年被发现后,如今其在反刍动物生产上的应用已经遍及全世界,同时对离子载体的研究也在不断深入。本文从离子载体的作用机理以及离子载体在能量代谢、氮代谢、消化紊乱相关疾病和安全方面的研究概况进行了综述,并提出了离子载体今后的研究方向。