Sodium fertilizer application to pasture. 4. Effects on mineral uptake and the sodium and potassium status of steers

Mineral availability and status in body tissues was examined with four rumen-fistulated steers arranged in a Latin-square change-over design. The steers were fed perennial ryegrass herbage from a pasture fertilized with four Na treatments: 0 (Nil), 32 (Low), 66 (Medium) or 96 (High) kg Na ha^-1 yr^-1. Na fertilizer increased herbage contents and intakes of Na, Mg and Ca but did not affect intakes of K, P and S. Herbage K:Na and K:(Ca+Mg) decreased in direct proportion to the amount of Na fertilizer applied. With increasing dietary Na intake, the Na content of saliva increased and the K content decreased. There was an increase in Na and a reciprocal decrease in K contents of rumen fluid with increasing dietary Na. Blood plasma Na contents were greater when the Na-treated herbages were fed than in the Nil treatment. There was no effect of treatment on blood plasma K content. Increasing dietary Na increased urinary Na but did not affect urinary K. Faecal mineral concentrations of Na, Ca, P and S were increased by increasing dietary Na, whereas K content was reduced and the Mg content was unaffected. There was no difference between treatments in the proportion of mineral rapidly solubilized, except Na which increased with increasing dietary Na content. The fractional rate of degradation was greater for Na, K, and Mg than for Ca and P. Based on effective solubilization, minerals were ranked in the order K > (Mg = Na) > Ca > P, and treatments were in the order Medium > (High = Low) > Nil. Increasing Na intake increased Ca but not P or Mg availability and increased the uptake of all three minerals.     

Sodium fertilizer application to pasture. 3. Rumen dynamics

The objective of the present experiment was to examine the effects of 0 (Nil), 32 (Low), 66 (Medium) or 96 (High) kg sodium (Na) ha^-1 yr^-1, applied as fertilizer to zero-grazed perennial ryegrass pasture, on rumen digestion and feed and water intake of steers. Herbage Na contents increased with increasing Na up to the Medium Na treatment and no further at the High. Dry matter (DM) contents were increased by Na fertilizer but not affected by the level. Herbage crude protein (CP), true protein (TP) and non-protein nitrogen (NPN) fractions were not affected by treatment. Application of Na fertilizer increased the modified acid detergent fibre (MADF) and ash and total cation content of herbage, particularly at the Medium and High treatments. Faecal DM and TP contents were not affected by treatment, but the CP, NPN, MADF and ash and total cation contents were increased by Na fertilizer. Herbage DM intake increased in proportion to dietary Na content. Water intake increased with increasing Na fertilizer level. Rumen pH was increased by Na fertilizer but ammonia concentration was not affected. The rapidly (a), slowly (b) and potentially (a + b) soluble fractions of degradable DM and the effective degradability (P) of DM increased in direct proportion to amount of Na fertilizer applied up to the Medium level, above which b was reduced and a, a + b and P did not increase further. Solid and total outflow rates were not affected by treatment. Liquid outflow rates were greater in the Medium and High treatments than in the Nil and Low treatments. The immediately soluble fraction of MADF was increased in the Na-applied treatments but the increase declined with each additional Na level. The degradability of MADF increased with increasing dietary Na, particularly in the High treatment. Na increased the proportion of small particles and those with a high specific gravity. It is suggested that the high dilution rates that accompanied the high water intakes and the increased rumen pH are essential factors enabling increased DM intake and rumen digestion when high Na herbages are fed to steers.     

Sodium fertilizer application to pasture. 1. Direct and residual effects on pasture production and composition

Results are given on the effect of sodium (Na) fertilizer applied as NaNO₃ in five application sat 0 (Nil), 32 (Low) or 64 (High) kg Na ha ^-1yr^-1 and the residual effect of sodium chloride(NaCl) fertilizer applied in the previous year on the growth rate and the chemical composition of herbage cut at fortnightly intervals over the grazing season. Na fertilizer at Low and High rates increased herbage Na contents by 20 and 40% respectively. Magnesium (Mg) content in herbage was increased at Low Na fertilizer application rate but there was no difference between the Nil and the High Na treatments. Calcium (Ca) content was increased in proportion to Na fertilizer level. Potassium (K) content of Nil Na herbage exceeded that of Low and High, but there was no effect of treatment on total harvested K yields. The contents of phosphorus (P), sulphur (S), true protein (TP) and modified acid detergent fibre (MADF) in herbage were not affected, but the dry matter digestibility (DMD) was increased with increasing Na fertilizer level. Applying Na fertilizer at the Low and High levels gave similar increases in water-soluble carbohydrates (WSC) and ash contents and decreased crude protein (CP) and non-protein nitrogen (NPN) contents. Net herbage accumulation(fresh and dry weight) was increased by 15 and 26% at the Low and High Na fertilizer application rates respectively. NaCl fertilizer residues from the previous year increased herbage Na, DM, DMD and WSC contents, reduced K contents and did not affect Ca, P, S, CP, TP and NPN contents. Residues from Na fertilizer decreased MADF and ash contents at the Low and High Na application rates. The main and residual effects of Na fertilizer were generally maximal in early season and diminished as the season progressed, with many of the effects eliminated by late season. Proportionally 0·70 of Na applied was recovered in the first two grazing seasons after application. The effects of Na fertilizer on mineral ratios are also described, together with the implications for animal health.     

The mineral metabolism of sheep fed high- and low-magnesium selections of Italian ryegrass

Two experimental populations of Italian ryegrass selected for high and low magnesium content were established as swards, harvested fresh daily and offered to sheep. Chemical analysis of the crops showed a 44% higher Mg and a 22% higher Ca concentration in the high-Mg selection but no significant differences between the selections for the other minerals.
Blood and rumen contents were sampled throughout the feeding period and voluntary intake, digestibility and mineral balances for Na, K, Mg, Ca and P were determined. Magnesium intake, apparent availability and retention were significantly greater with the high-Mg selection. There were no significant differences in the plasma-mineral concentrations and all were within the normal range. Rumen fluid from animals fed the high-Mg selection had a higher proportion of soluble Mg and a higher Na:K ratio in the supernatant liquor.     

Effects of variation in herbage sodium levels and salt supplementation on the nutritive value of perennial ryegrass for sheep

Six groups of five 18-month-old wether sheep received a diet of dried grass ad libitum with a pelleted ground barley/oat supplement containing various levels of salt for 30 d. The first group received grass of high Na concentration (7·3 g per kg DM) with no added salt in the supplement, a second group received low sodium grass (4·2 g per kg DM) with no salt additions, and the other four groups received the low sodium grass with varying levels of salt added to the supplement to provide a final dietary Na concentration ranging from 7·0 to 18·0 g per kg DM.
Dry matter (DM) and organic matter (OM) intakes were significantly reduced for groups receiving salt supplementation. The digestibilities of DM and OM were reduced for all groups on the low sodium grass diets compared with the high sodium grass diet, but were not affected by salt supplementation.
No consistent changes were observed in the molar proportions of volatile fatty acids in rumen fluid, but N availability and retention were higher for the animals on the high sodium grass diet.
The high sodium grass diet gave a better apparent availability and retention of minerals than the low sodium grass diets and, while addition of salt tended to improve the availability of minerals, the urinary loss of minerals increased with salt addition to the diet.
There were no changes in plasma Na levels, and plasma K changes were inconsistent. However, plasma Ca concentration was reduced significantly for salt-supplemented diets with a Na concentration above 7·0 g per kg DM, and plasma Mg was significantly depressed at dietary Na concentrations above 15·0 g per kg DM.     

STUDIES IN RESPONSE TO NITROGEN

Data are presented demonstrating the effects of applying fertilizer N at 59, 118 or 177 kg/ha on 16 Apr. on uptake of K, P. Ca, Mg and Na in primary growth (PG) harvested 8, 12, 16, 23, 29, 45 and 57 days afterwards, and residual effects in two successive regrowths (RG1 and RG2) harvested on 12 June and 13 Aug., respectively. Significant residual responses as uptake of K, P, Ca, Mg and Na were shown in RG1 and RG2 after all dates of harvesting PG. The residual responses compensated for poor uptake in PG. Thus, low uptakes to the second increment of N were followed by high residual responses in both regrowths; and low uptakes in PG harvested shortly after applying the fertilizer N were followed by high residual responses. Averaged over the seven dates of PG harvest, the sum of responses (PG+RG1+RG2) to the second N increment was greater than total response to the first increment in P and Mg, considerably greater in Ca and Na and slightly lower in K. These marked residual responses to the second N increment were most noticeable where PG was harvested 23 days after applying fertilizer N and became less marked as date of PG harvest was advanced. Percentage K, P, Ca, Mg and Na in DM of the PG and of RG1 increased as N application was raised. By RG2, the residual effects of fertilizer N on percentage K. P and Mg were reversed to give reduced percentages with increased N application to PG. indicative of deficiencies in availability of these elements. The application of 177 kg N/ha to PG resulted in the release of additional soil N and of other mineral elements which could lead to their depletion.     

Soil determinants for distribution of Halocnemum strobilaceum Bieb. (Chenopodiaceae) around Lake Tuz, Turkey

In this study we aimed to reveal the ranges and effectiveness of soil parameters on the distribution of H. strobilaceum. Halocnemum strobilaceum Bieb. is a widespread species in saline habitats and the distribution pattern of this halophytic species around Lake Tuz in Central Anatolia was examined according to the soil characteristics. pH, electrical conductivity, soil humidity, salt percentage, soluble Ca2+, Mg2+, Na+, K+, CO3(2-), HCO3(-), Cl(-) and SO4(2-) values, total cations, cation exchange capacity, sodium adsorption ratio, exchangeable Na+, K+, Ca2+ and Mg2+ values were the examined soil properties. The most effective soil parameters for flowering period were found as Na, SO4, total cations, SAR and EC and for seed bearing period as EC, Mg, total cations, Cl, Na, SO4 and salt (%) content of the soil.     

茶园土壤钾素容量／强度关系及施用钾镁肥的影响

对我国主要茶区茶园土壤分析结果表明，土壤钾素含量大都处于中等水平以下，且呈地带性分布，即缓效钾的含量由北而南下降，速效钾占缓效钾的比例由北而南增加。对土壤钾素容量／强度（Ｑ／Ｉ）分析表明，茶园土壤钾素的ＡＲｋｅ（强度指标）通常都小于０．０１（ｍｏｌ／ｌ）－１２。施用钾肥能显著提高供钾强度指标ＡＲｋｅ和ΔＫ０（容量指标）。施镁能增加ＡＲｋｅ，但对ΔＫ０和ＰＢＣｋ（缓冲能力）无明显影响。不施钾处理土壤的ＡＲｋｅ和ΔＫ０均趋于下降     

尿素和茶树落叶对荒地土壤元素迁移的影响

用亚热带茶区的3 种未垦荒地土壤进行土柱模拟, 研究重施尿素和表覆茶树落叶对土壤中Si、Al、K、Na、Ca、Mg 等6 种元素迁移的影响。结果表明, Si 的淋出量和Al+ K+ Na + Ca +Mg 的淋出总量均以黄棕壤> 红壤> 赤红壤。尿素和茶树落叶处理对硅淋出量的影响较小, 但可使各土壤主要的淋失元素, 包括赤红壤中的Ca 和Na, 红壤中的Ca 和Al 及黄棕壤中的Na、Ca和Mg 的淋失量明显增大, 从而使Al+ K+ Na+ Ca+ Mg 的淋出总量在3 种土壤中分别比对照柱增加163 % 和58% 、64 % 和57 % 、140 % 和84 % , 尿素的促进盐基和Al 淋失作用比茶树落叶更强,两者都可加速土壤的酸化。     

Sodium fertilizer application to pasture. 6. Effects of combined applications with sulphur on herbage production and chemical composition in the season of application

The effect of sulphur and sodium fertilizers on the response of a perennial ryegrass ( Lolium perenne ) sward was examined over 2 years. Sulphur fertilizer was applied as ammonium sulphate at 0 or 97·5 kg S ha⁻¹ year⁻¹ and sodium fertilizer as sodium nitrate at 0 (nil), 31 (low), 62 (medium) or 94 (high) kg Na ha⁻¹ year⁻¹, with nitrogen input balanced across all treatments. Both sulphur and sodium increased herbage yield. Sodium fertilizer increased herbage sulphur concentration and sulphur fertilizer slightly increased herbage sodium concentration, but there were no major interactions between the two fertilizers on herbage yield or composition in the season of application. Sodium fertilizer increased dry-matter digestibility, water-soluble carbohydrate concentration and the live proportion of the herbage. Herbage sodium and magnesium concentrations were increased and potassium concentration decreased by sodium fertilizer. Sulphur fertilizer increased herbage dry-matter digestibility and water-soluble carbohydrate concentration. Sulphur and potassium concentrations were also increased and non-protein nitrogen, magnesium and phosphorus concentrations decreased in response to sulphur fertilizer. It is concluded that, although there was evidence of facilitation of sodium uptake by sulphur fertilizer and vice versa, this was not sufficient to produce synergistic effects on herbage growth in the season of application.     

Sodium fertilizer application to pasture. 8. Turnover and defoliation of leaf tissue

The effects of application of sodium fertilizer on the turnover and defoliation of leaf tissue were investigated in a perennial ryegrass (Lolium perenne) pasture grazed by dairy cows. Eight plots were allocated to treatments either with or without sodium fertilizer, with the former receiving 32 kg Na ha^–1 applied in five applications of NaNO₃ over the grazing season. An equivalent amount of nitrogen was given to the controls as ammonium nitrate, the application of which was reduced in the sodium treatment to equate nitrogen fertilizer applications for the two treatments. In nine periods between April and September, marked tillers were recorded to measure leaf turnover, leaf lamina growth and specific leaf weight and, when combined with tiller density measurements, gave an estimate of herbage flux for the sward. The defoliation and net growth of the marked tillers were monitored at 3-day intervals and the data were combined with tiller density and specific leaf weight data to determine the intake of the expanding, penultimate and oldest live leaf laminae. Sodium fertilizer application did not affect the rate at which leaves appeared, but it retarded their rate of disappearance. The extension rate and the specific weight of green laminae were both increased by sodium fertilizer application and therefore the net gravimetric growth rate was increased. Tiller density was not affected by sodium fertilizer application and hence the estimated herbage growth and net herbage flux were increased by sodium fertilizer application. Application of sodium fertilizer did not affect lamina length, and in both treatments the penultimate laminae were approximately twice as long as expanding and oldest live laminae. Defoliation frequency decreased from the expanding to the oldest live laminae in the control treatment without sodium. Sodium fertilizer application increased the frequency of defoliation of the oldest live leaf and also increased the length of the expanding leaf that was defoliated. For penultimate leaf laminae sodium fertilizer application reduced the defoliation frequency and length of foliage grazed. The dry-matter (DM) intake of the oldest live laminae was increased by the application of sodium fertilizer. It is concluded that sodium fertilizer application increases net herbage growth both by increased extension rate of leaf laminae and specific leaf weight and by delayed laminae senescence, and that it increases herbage DM intake by increasing the defoliation frequency of the oldest live leaf laminae.     

EFFECTS OF NITROGEN FERTILIZATION OF MIXED SWARDS ON HERBAGE YIELD, DRY MATTER DIGESTIBILITY AND VOLUNTARY FOOD INTAKE OF THE CONSERVED HERBAGES

In 2 experiments nitrogenous fertilizer was applied at 3 levels (0, 46 and 92 lb N/ac) to a permanent pasture and a ryegrass/clover ley and the swards were harvested before ear emergence and conserved as either artificially dried grass or tetrapod hay. Apparent dry matter digestibility and voluntary food intake of the conserved herbages were measured with sheep.
N caused a small but significant depression in apparent DM digestibility but did not affect voluntary food intake. It increased yields of DM and digestible DM significantly.
The DM digestibility and voluntary food intake of hay were always significantly lower than those of the corresponding dried grass. Voluntary food intake of all fodders was directly related to herbage digestibility and inversely related to herbage crude fibre content.     

Chemistry of groundwater of Al-Ahsa Oasis eastern region Saudi Arabia and its predictive effects on soil properties

Saudi Arabia is an arid and the largest country in the middle east with a total land area of 2.253 x 10(6) km2. Recent urban and rural expansion has shown manifold increases in water use in various sectors. Water resources are limited and non-renewable coupled with unpredicted scanty rainfall. In order to meet the rising water needs, evaluation of water quality is important for allocation to various uses. A total of 101 well water samples were collected from Al-Ahsa Oasis. Water samples were analyzed for total salt concentration, pH, Ca, Mg, Na, K, HCO3, Cl, SO4, NO3, F and B contents. Soil Salinity Development (SSD), adjusted sodium adsorption ratio (adj.SAR), adjusted sodium adsorption ratio (adj. R(Na)) and Exchangeable Sodium Percentage (ESP) were calculated. The EC of groundwater ranged between 1.23 and 5.05 dS m(-1). Sodium was the most abundant cation followed by Ca, Mg and K in descending order. Chloride was the most abundant anion followed by SO4 and HCO3 in groundwater of Al-Ahsa Oasis. A significant correlation was found between Na and Cl (R2 = 0.936). Thermodynamics calculation revealed that an appreciable amount of Ca and Mg is associated with Cl and SO4 ions. The SAR and ESP values are within the permissible limits according to Ayers and Westcot, 1985. The NO3 concentration is within safe limits for drinking purpose according to WHO (1998) standards. The Saturation Indices (SI) indicated that groundwater is under-saturated (negative SI) with respect to certain minerals (for example: calcite, dolomite, gypsum, anhydrite, halite, pyrite, fluorite and aragonite) and oversaturated (positive SI) with respect to some other minerals (For example: Goethite, Siderite and hematite). The negative saturation index (SI) reveals that most of minerals are in un-saturated state and will dissolve more Ca and Mg into the soil solution after irrigation. A good relationship exists between Cl and other ions (Na, Ca and Mg) as well as between SO4 and Ca and Mg ion of groundwater. The salinity and sodicity hazards of groundwater of Al-Ahsa Oasis were classified as C3S1 and C4S2 i.e., high salinity with medium sodicity problems. The predicted soil salinity suggested application of 15-20% leaching requirements to keep soil salinity within permissible limits. Cultivation of slight to moderate salt and sodium tolerant crops is recommended for optimal agricultural production and efficient water use.     

Response of permanent and reseeded grassland to fertilizer nitrogen. 2. Effects on concentrations of Ca, Mg, K, Na, S, P, Mn, Zn, Cu, Co and Mo in herbage at a range of sites

The concentration of mineral elements in herbage from permanent swards of mixed species composition (predominantly Agrostis spp., Holcus lanatus, Festuca rubra, Lolium perenne, Poa spp., etc.) was compared with that from sown perennial ryegrass ( Lolium perenne ) at two fertilizer rates (0 and 300kg N ha⁻¹ year⁻¹, both with P and K) and with L. perennel Trifolium repens (at 0 N with P and K). The investigation was conducted over four years at sixteen contrasting sites in England and Wales. Herbage samples for mineral analysis were taken at first and fourth harvests (May and August) each year from plots under 4-weekly cutting. There was a wide degree of variation between sites, particularly for concentrations of Ca, Mg, Na and all trace elements analysed. Herbage from L. perenne reseeds had significantly higher concentrations of Ca, Mg, Na, Co and S, but K, Mo, Zn, Cu and P were generally lower than in the permanent swards. L. perennel T. repens swards had the highest concentration of major cations, but trace element levels were generally intermediate between those for 0 N permanent and L. perenne swards. Fertilizer N reduced concentrations of Ca, Mn, Mo and S, and increased Mg, Na and Zn, with no consistent effects on K, Co and Cu. Herbage at harvest 4, compared with harvest 1, had higher Ca, Mg, Na, Mn, Zn and S. Permanent and L. perenne swards responded similarly to fertilizer N and between harvest dates. Results are discussed in relation to previous reports of botanical and fertilizer effects on mineral concentrations, and the mineral requirements of livestock. Changes in mineral concentration resulting from reseeding permanent swards are considered unlikely to increase mineral-related livestock disorders, and in many cases could be beneficial, though problems might arise on sites where some elements, e.g. Cu and Mg, are low.     

不同木薯种质资源主要矿物质元素差异性分析

为了解不同木薯种质资源矿物质元素含量,优选含量丰富的品种,为木薯的综合利用提供数据支撑,本文采用马弗炉法、原子吸收和原子荧光法分别对113份木薯种质资源灰分与矿物质元素含量进行测定,结果表明：矿物质元素Cr、Cu、Se含量均低于1 mg/kg（干重）,Ca、Fe、K、Mg、Mn、Na、Zn含量分别为66.39~1609.81 mg/kg、4.35~ 38.93 mg/kg、1954.56~8762.78 mg/kg、149.04~1143.73 mg/kg、4.48~37.40 mg/kg、36.80~530.40 mg/kg、6.35~24.83 mg/kg。利用概率分级法将113份木薯种质资源灰分及矿物质元素含量分为5级,即极高、高、中、低和极低,并推荐极高品系作为基础亲本材料。在相关性分析中,灰分与Fe、Mg、Na、Zn含量具有较为显著的相关性,Ca含量与K、Mn含量呈极显著正相关,Ca含量与Mg、Na含量呈极显著负相关,Fe含量与Mg、Na、Zn含量成极显著正相关,K含量与Mn含量呈极显著正相关,与Na含量呈极显著负相关,Mg含量与Na、Zn含量呈极显著正相关,Zn含量与Mn、Na含量呈极显著正相关。Zn与各矿物质元素的吸收有较强的相互促进作用,Fe含量与Mg、Na含量有较强的相互促进作用,Ca含量与K、Mn的吸收有较强的促进作用,而Ca、K、Mn与Fe、Mg、Na的吸收可能存在一定的拮抗作用。结合主成分分析、聚类分析对不同木薯种质资源矿物质元素含量进行综合评价,得到特征值大于1的主成分2个,累计方差贡献率达61.707%。聚类分析可将113个木薯种质资源分为3类,根据矿物质元素含量差异可将不同木薯品种分为Na、Mg、Zn、Fe含量较高和Mn、Ca、K、Zn含量较高两大类,主成分综合评价中‘274'‘50'‘571'‘521'‘417'等木薯种质资源得分较高。     

Concentrations of N, P, K, Ca, Mg and Na in perennial ryegrass and white clover leaves of different ages

Leaf blades of perennial ryegrass ( Lolium perenne ) at five developmental stages, from unemerged to dead, were collected from cut swards grown under field conditions. Similarly, leaflets of white clover ( Trifolium repens ) at four developmental stages, from tightly folded to proximal to the youngest fully developed leaf, were collected. The leaves were analysed for N, P, K, Ca, Mg and Na.
In perennial ryegrass, the concentration of N declined by about half and those of P and K declined by about two-thirds, as leaves aged. By contrast, the concentration of Ca increased more than fivefold and that of Mg about twofold as leaves aged. The concentration of Na initially increased more than twofold but then declined as leaves died. In white clover the concentration of N declined by about 20% as leaves aged, while the concentrations of P and K declined by about 50%; the concentration of Ca increased about fivefold, that of Mg declined by about 15% and that of Na increased by about 15%.
The application of N increased the concentrations of N and K in ryegrass leaf blades at all stages of development. The application of P increased the concentrations of P and Na in the leaves of both species.     

Nitrogen Uptake by the Rice Plant and Changes in the Soil Chemical Properties in the Paddy Rice Field during Yearly Application of Anaerobically-Digested Manure for Seven Years

Abstract

This study investigated the changes in the chemical properties of the plow soil during a 7-year period with yearly application of anaerobically-digested manure (ADM), and the effect of the different ADM application methods on nitrogen (N) uptake by rice plants and the apparent N balance (input N minus output N). Among the treatments significant differences were observed in the pH, total N, and available N in the plow soil. The cumulative N uptake by rice plants in the ADM split application plots was significantly higher than that in single application plots. Consequently, the apparent N balance (input N minus output N) in the single ADM application plots was more positive. This result suggests that split application of ADM is more favorable for N uptake by rice plants. Although the apparent N balance was negative in the plots without N fertilizer, with chemical N and with low ADM, there was no observable decline in the total N and available N in the plow soil. This result implies that input and output of N in these plots were well balanced by additional N supply other than fertilization. On the other hand, the apparent N balance during the 7-year study under standard and heavy application of ADM was positive, indicating the preservation of soil fertility.     

The prediction of the in vivodigestibility of the diet of sheep and cattle grazing indigenous hill plant communities by in vitrodigestion, faecal nitrogen concentration or indigestible' acid-detergent fibre

Herbage and faeces samples were retained from an intake and in vivo digestibility trial using material harvested at three different stages from five indigenous hill plant communities (those dominated by Agrostis-Festuca., Nardus stricta., Molinia caerulea., Eriophorum vaginatum and Tri-chophorum caespitosum) and from sown swards of ryegrass or white clover. Samples of the herbages and of their separate components, together with extrusa samples of the same herbages recovered from pen-fed sheep and cattle oesophageal fistulates, were digested in vitro using rumen liquor. Measurements were made also of faecal nitrogen concentration (FN) and of indigestible acid-detergent fibre (IADF) using the samples from the original trial.
The range of in vitro disappearance values of the herbages (IVOMD; 0809-0278) was slightly wider than those of in vivo digestibility (OMD; 0-796-0-37I). Differences between OMD and IVOMD were greatest at low quality and relationships were best described by two separate linear regressions of OMD on IVOMD for (a) ryegrass, white clover, Agrostis-Festuca and Nardus (RSD; 0 0185) and, (b) Molinia, Tricho-phorum and Eriophorum (RSD; 00246). In vitro disappearance values of extrusa were higher than those of herbages offered by 00503 and 00156 units for sheep and cattle respectively, partly because of greater levels of ensalivation, especially in the sheep. The relationships of OMD to IADF and to FN were poor, though inclusion of faeces output and fitting parallel lines for communities in the regression of OMD on FN reduced the RSD to 0020. We conclude that in vitro digestion of samples of extrusa, using appropriate standards, is the best method of diet digestibility prediction for sheep and cattle grazing these communities.     

Removal of mineral nutrients by red clover varieties

K, P, Ca and Mg contents and uptakes are reported from total herbage of plots sown with six varieties of red clover harvested three times a year for 3 years. K, P and Mg contents were above those reported as critical for growth; values for Ca were lower than quoted ranges which suggested that growth might have been affected by either deficiency of Ca or low pH. Hungaropoly was characterized by relatively low K and P and high Ca contents. Maximum uptakes in red clover total herbages over 3 years were 1198 kg ha^?1 K (Hera), 112 kg ha^?1 P (Hera), 494 kg ha^?1 Ca (Hungaropoly) and 104 kg ha^?1 Mg (Mars). Results were compared with those found for S101 perennial ryegrass, harvested on a similar system and receiving similar fertilization with uptakes of 759 kg ha^?1 K, 100 kg ha^?1 P, 200 kg ha^?1 Ca and 46 kg ha^?1 Mg, by expressing accumulating uptakes and inputs as linear regression equations. The better varieties of red clover, Hera, Hungaropoly, Mars and S123 show rates of DM accumulation similar to S101 perennial ryegrass and similar uptake rates of K and P but higher rates of uptake of Ca and Mg. The levels of application of K and P used in the experiment seem to be more than adequate but attention to the Ca status may be required to sustain high-yielding red clover swards.     

Re-ensiling effects on inoculated sorghum: Intake,apparent digestibility,nitrogen balance,and animal feeding behaviour

This study aimed to determine whether using inoculants and re-ensiling in sorghum silages affect the intake and feeding behaviour, apparent digestibility, digestible energy, and nitrogen balance of sheep in maintenance. Half the sorghum was inoculated on the day of harvest, and the other half received the same inoculation volume but with water. Sorghum was ensiled in 100 experimental metal drum silos of 200 L covered with plastic: 50 silos with inoculants and 50 without them. After 56 days, 25 drums with inoculants and 25 without were exposed to air for 48 h. The other silos remained closed. The treatments were arranged in a 2 × 2 factorial scheme with inoculation and re-ensiling. The sheep received the silages after 211 days of ensiling and 155 days of re-ensiling to determine the intake, apparent digestibility, and feeding behaviour of animals. The experimental design was a simultaneous double 4 × 4 Latin square. The re-ensiling process increased silage pH, N-NH₃.TN⁻¹, butyric acid, and propionic acid. The inoculant increased propionic acid in ensiled and re-ensiled silages. Lactic acid concentration presented a statistical interaction with the inoculated and ensiled silage, 58% higher than the other treatment averages. The ADFap digestibility showed a complex interaction, in which the control ensiled and the inoculated and re-ensiled silages were about 35% lower than the inoculated ensiled silage. The Nbal:Nint ratio (g.g⁻¹) in the inoculated and re-ensiled silage had lower nitrogen retention than intake compared with the other treatments. These results indicate that exposing inoculated silages to air does not compromise their use in sheep feeding.