bluuebunny/crossref_metadata_2025 huggingface dataset:
Monitoring changes in timber volume using aerial photo plots and field plots in a two-phase sampling design.
Authors: Stellingwerf D.A. , Gier A. de
Published: June 2020

Standing timber volume and mean periodic volume increment (of Norway spruce - Picea abies - age 40-100 yr) were determined over a period of 10 yr (1974-84) in a 3000 ha forest area in Austria. The results of a Two-Phase Linear Regression Sampling (TPLRS) method (using 112 circular photo plots in the first phase, and 55 dependent field plots in the second phase, each covering 0.05 ha) were compared with those of a Simple Random Sample (SRS) of only field plots (112). The crown cover percentages per plot were taken as independent variables in the TPLRS. They were stereoscopically determined on 1:10 000 scale black and white infrared aerial photographs of 1974 and 1984. Results from TPLRS were comparable to those from SRS and did not require re-enumeration of the field plots in 1984. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effects of continuous and intermittent carbon dioxide enrichment on fruit set and yield of sweet pepper (Capsicum annuum L.).
Authors: Nederhoff E.M. , Uffelen J.A.M. van
Published: June 2020

An autumn crop of cv. Delphin was subjected to 6 CO2 treatments viz. continuous CO2 levels near 200, 340 (ambient) and 500 p.p.m., intermittent dosing for 8 minutes/40 or in every 104 minutes, and a control (without dosing or filtering). The number of fruits harvested per msuperscript 2 was 60% higher in the 500 p.p.m. than in the 200 p.p.m. treatment, but the average fruit weight was not significantly affected. The dry matter content of the leaves increased, and the SLA and LAR were smaller at higher CO2 concentrations. Vegetative growth tended to decrease at higher CO2 levels, probably because of competition between vegetative and generative organs. The effects of CO2 on setting and yield were less favourable with intermittent than with continuous CO2 enrichment for the same average concentration. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Disinfection of drainwater from soilless cultures by heat treatment.
Authors: Runia W.T. , Os E.A. van , Bollen G.J.
Published: June 2020

In closed systems with soilless cultures, recirculation of drainwater favours the spread of root-infecting pathogens. An installation was designed for disinfection of drainwater by heat treatments at high temperatures (more than 90 degrees C) for short periods (approx. 10 secs). The energy input was low because of efficient use of heat exchangers. Preliminary results of glasshouse experiments showed that tobacco mosaic virus and Verticillium dahliae were effectively controlled. Longer exposure times are probably required for complete elimination of Fusarium oxysporum f. sp. melongenae. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Flower sprayings with plant growth regulators and fungicides to improve the yield of glasshouse eggplants (Solanum melongena L.).
Authors: Ravestijn W. van
Published: June 2020

Of the PGRs and fungicides tested, a mixture of 20 mg/litre 4-chlorophenoxyacetic acid, to improve fruit growth, and 500 mg/litre iprodione, to control fruit rot, on flower buds ( at
The influence of autumn cutting on canopy structure and seed production of first-year crops of Poa pratensis L and Festuca rubra L.
Authors: Meijer W.J.M. , Vreeke S.
Published: June 2020

In field experiments in 1981-86, Poa pratensis cv. Kimono and Baron and Festuca rubra cv. Agram and Koket were undersown in companion crops of winter wheat cv. Arminda. Cuts were made immediately after wheat harvest or 4-6 weeks later. N application as autumn and spring dressings did not alter the effects of cutting. In most experiments, cutting treatments increased production of inflorescence and seed yield, mainly due to better illumination, and increased survival of the late elongating reproductive tillers. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Extensification of dairy farming and floristic richness of peat grassland.
Authors: Strien A.J. van , Melman C.P. , Heiden J.L.H. de
Published: June 2020

A comparative study of floristic richness of 125 permanent peat grasslands was made in 1983-84 across Zuid-Holland and Utrecht provinces. Three different parameters of floristic richness were used: the number of species, the number of those species that contribute to the conservational value (quality indicating species) and a 'nature value' index that combines species richness with rarity of species. N supply (0-600 kg N/ha per year) was the most important factor determining number of quality-indicating species. Additional factors were peat mud dressing and soil type. Utilization of grassland (whether frequently cut or continuously grazed), ground water table level, pH, P and K contents of the topsoil and type of animal manure had no effect on floristic richness. At levels below 200 kg N/ha per year, a considerable number of species of conservational value (e.g. Lychnis flos-cuculi and Carex nigra) became abundant. The significance of the results for nature conservation with regard to current agricultural practice is discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Oenothera species and Borago officinalis: sources of gamma-linolenic acid.
Authors: Muuse B.G. , Essers M.L. , Soest L.J.M. van
Published: June 2020

Seed samples of 23 Oenothera species (O. biennis and O. lamarckiana in particular) and of B. officinalis, cultivated in 1986, were analysed. In B. officinalis, 7.1% (by weight) of gamma -linolenic acid (GLeA) was found in the whole seed whereas in Oenothera species the average was 2.3%. The mean content of oil in the seeds was 30.8 and 21.2%, respectively. The GLeA content was positively correlated with the seed oil content. The fatty acid composition of Oenothera oils showed only little variation between the different species grown in a particular year. The soil type, sand or clay, did not significantly influence the GLeA and other fatty acid contents of Oenothera species. It was concluded that the production of GLeA from B. officinalis can be as much as 3 times that in Oenothera species on the basis of similar seed yields for both crops and disregarding the poor seed retention of B. officinalis. The high level of GLeA emphasises the higher quality of Borago oil, in comparison to that of Oenothera, when used to compensate a lack of GLeA in man caused by Delta 6-linoleic desaturase deficiency diseases. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Genetic and environmental variation in quality of forage maize in Europe.
Authors: Deinum B.
Published: June 2020

Various forage maize hybrids were grown in 24 trials in Europe in 1985-86 and harvested at silage maturity to investigate the variation in quality. Av. apparent OM digestibility of the whole crop was high at 73.5% (range 64.7-81.4%). The range in digestibility or nutritive value between locations was small but genetic differences in digestibility of the various hybrids over the locations was greater. Maize of 75% digestibility could be grown in all countries. Digestibility could be raised to 80% by breeding for higher digestibility of cell walls of the straw. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Extrapolation and interpolation by time-scaling in systems with diffusion-controlled kinetics and first-order reaction rates.
Authors: Zee S.E.A.T.M. van der , Riemsdijk W.H. van , Grinsven J.J.M. van
Published: June 2020

The interpolation or extrapolation in time of physicochemical processes from experimental data is often difficult. A theoretically derived time-scaling procedure using an exposure variable of the concentration integrated in time, with at most one adjustable parameter was applied successfully to three systems taken from metallurgical, agricultural and environmental engineering. This scaling rule is potentially useful as a research or management tool for systems that are too complex for mechanistic modelling. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Genetic variation for seed yield components of Westerwold ryegrass (Lolium multiflorum var. westerwoldicum).
Authors: Elgersma A. , Den Nijs A.P.M. , Van Eeuwijk F.A.
Published: June 2020

Genetic variation for seed yield components was studied in 4 diploid varieties of Westerwold ryegrass, and 19 genotypes from each variety were grown in the field in 2 clonal replicate rows (minirows). The number of inflorescences/minirow, the numbers of spikelets/inflorescence and florets and seeds/spikelet, 1000-grain weight and seed yield/minirow were determined. Floret site utilization (FSU) was calculated as (seeds/floret) x 100%. Genotypic variation and heritabilities were calculated. Correlation studies and path analyses were carried out in each variety separately. Among varieties, no significant differences occurred for seed yield. However, within varieties large genetic variation was present for both seed yield and yield components. Path analyses revealed that relationships between seed yield components differed to a great extent among varieties. FSU was the major yield component in 3 varieties, but in one variety inflorescence number was the most important yield component. There was ample scope for genetic improvement of seed yield. FSU had a very high heritability and was not correlated with any of the other seed yield components. (Abstract retrieved from CAB Abstracts by CABI’s permission)
An analysis of the response of sugar beet and potatoes to fertilizer nitrogen and soil mineral nitrogen.
Authors: Neeteson J.J. , Zwetsloot H.J.C.
Published: June 2020

A statistical analysis was performed to investigate if, and to what extent, the response of sugarbeet and potatoes to fertilizer N depended on the amount of mineral N already present in the soil, soil type, and prior application of organic manures. For this purpose the results of 150 field trials with sugarbeet and 98 with potatoes were used. The analysis was focussed on the within-block stratum of variation in yield, where regression models were fitted to describe the response to N. For both sugarbeet and potatoes the best fit was obtained when not only fertilizer N was taken into account, but also soil mineral N, soil type and prior application of organic manures. The response to fertilizer N was weaker as the amount of soil mineral N was larger. The optimum amount of fertilizer N plus soil mineral N required was larger on sandy soils than on loam and clay soils. The difference was about 20 kg N/ha for sugarbeet and 100 kg N/ha for potatoes. When organic manures were applied prior to the application of fertilizer N, the optimum for both sugarbeet and potatoes was 15-50 N/ha lower than without application of organic manures. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Leaching of fluridone, hexazinone and simazine in sandy soils in the Netherlands.
Authors: Zandvoort R.
Published: June 2020

Fluridone and simazine were sprayed in field experiments on coarse and humic sandy soils in spring or in late autumn, and hexazinone on coarse sand in spring. After a spring application, over an eight-month period, fluridone and hexazinone were detected by bioassay in the profile of coarse sand from 0 to 60 cm, whereas simazine did not leach below 15 cm. Both fluridone and simazine were found to a depth of 60 cm in coarse sand after an application in late autumn. Thus, in winter conditions the transformation rate is not fast enough to prevent leaching of fluridone and simazine to deeper soil layers after autumn application. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Milling and air classification of two different types of peas - effects on the distribution of antinutritional factors.
Authors: Poel A.F.B. van der , Aarts H.L.M. , Stolp W.
Published: June 2020

The effect of milling and subsequent air classification of 3 cultivars of pea (Pisum sativum) on the distribution of trypsin inhibitors, lectins and tannins was studied. Two different milling procedures and two different classifier settings were investigated. Cut points were calculated from particle size distribution curves of the coarse and fine fractions. Proteinaceous antinutritional factors segregated into the fine fractions, the actual resulting values being dependent on the type of milling and the settings of the classifier. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Estimating the chemical composition of the soil solution of glasshouse soil. 2. Relationships between the compositions of soil solution and aqueous extracts.
Authors: Ende J. van den
Published: June 2020

The possibilities of estimating ECs and K, Na, Ca, Mg, NO3, Cl and SO4 contents of press extracts of glasshouse soils from corresponding analytical data of saturation extracts or 1:5 by-weight extracts were examined through construction of regression equations. The analytical data of saturation and 1:5 by-weight extracts were and were not corrected by multiplication with dilution factors, these being the ratios between the water contents of the soils employed to obtain the extracts and the water contents of the soils at field capacity. The dilution factors used were not derived from actual water contents but from water contents assessed on the basis of loss-on-ignition values. In a number of cases, the estimation technique could be improved through introduction of one or two extra variables, such as the dilution factor, the corrected SO4 content of the extract, the water content of the field-moist soil and the ratio between the mass fractions clay and loss-on-ignition. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Potential denitrification rates in acid soils under pine forest.
Authors: Kroeze C. , Faassen H.G. van , Ruiter P.C. de
Published: June 2020

Potential rates of N2O production and N2O reduction associated with denitrification were measured from two Dutch soil samples under pine [Pinus] forest, with pH (H2O) 3.6 and 3.8. Undisturbed cores of the surface 15 cm litter and Ah layer were incubated for several weeks in closed pots, of which the gas phase was examined by gas chromatography for O2, CO2, N2O and C2H2. Under anoxic conditions created by soil respiration, average N2O-N production rates in samples from these soils ranged from 9 to 15 mu g cm-2 day-1 and average N2O-N reduction rates from 3 to 6 mu g cm-2 day-1. Rates of N2O production and N2O reduction were measured at two initial nitrate concentrations: N2O production rates were almost the same, but N2O reduction seemed to be delayed by the presence of nitrate. The results indicate that anoxic denitrification peaks might reduce about 1 kg nitrate-N per ha per day in the upper layer of these soils to N2O and/or N2. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A model approach to analyse sowing strategies for maize in southern Mozambique.
Authors: Schouwenaars J.M. , Pelgrum G.H.
Published: June 2020

In S. Mozambique, rain falls mainly between Oct. and Apr. Year by year fluctuations of rainfall are extremely wide and rainfall is very erratic. In the sandy soils of the coastal zone, capacity for water retention is very low. Production and consumption of maize is also affected by losses caused by pests and diseases and post-harvest losses. A simple water balance and crop growth model was applied to simulate production of maize for different sowing strategies. Available maize for consumption per month for an average family farming unit was determined for the period 1957-85. Model parameters which describe soil water availability were varied to study their impact upon sowing strategies. Values for potential production were also varied. For maximizing yearly consumption the preferred strategy almost fully depended on losses by pests and diseases and post-harvest losses. However, regarding the decision criterion of minimizing the periods with food shortage the preferred sowing strategy greatly depended on water availability and potential production levels. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Modelling the effects of needle mortality rate and needle area distribution on dry matter production of Douglas fir.
Authors: Mohren G.M.J. , Bartelink H.H.
Published: June 2020

A physiological simulation model was used to analyse the effects of increased needle mortality rate and changes in needle area distribution (LAI) on primary production of a Douglas fir (Pseudotsuga menziesii) stand. Needle life-span, which may decrease as a result of air pollution and soil acidification, is an important aspect of forest decline. Results show that simulation models can be used to study the possible consequences of these phenomena in forest stands. The model quantified the relationship between total LAI and stand growth (taking into account different light distributions within the canopy that result from needle area distribution and clustering of needles). The effect of an increase in needle mortality rate was strongly dependent on initial LAI: at low initial LAI, productivity will decrease as a result of an increase in needle mortality and decreased light interception; at high initial LAI, light interception does not necessarily decrease significantly when needle mortality increases, but productivity may even increase because of decreased maintenance respiration. These effects are discussed, and compared with other species, such as Scots pine (Pinus sylvestris) which has a relatively low LAI. The authors recommend using more quantitative techniques in forest decline inventories (e.g. estimating LAI from light interception measurements) in order to account for these LAI differences. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Economic losses due to bovine mastitis in Dutch dairy herds.
Authors: Schakenraad M.H.W. , Dijkhuizen A.A.
Published: June 2020

Current annual losses due to mastitis in Dutch dairy herds were calculated to av. Dfl 136/cow per yr, which equals approx. 12% of net return on labour and management per cow on a typical farm. Reduction in milk and fat yield accounts for 70% of these losses. Streptococcal infections were found to have the highest economic impact, causing almost 40% of total losses. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Pre- and postheading growth rate and its association with grain yield in barley.
Authors: Salman A.A. , Brinkman M.A.
Published: June 2020

Preheading and postheading growth rates, grain yield and other traits were evaluated in 5 cultivars grown at 2 sites in Wisconsin (Madison in 1985 and Arlington in 1985 and 1986). The experimental design was a randomized complete block with 4 replications. Significant differences were observed among cultivars in preheading and postheading growth rates and DM accumulation. Correlation coefficients for growth rate at maturity and postheading growth rate with grain yield were highly significant (r = 0.93 and 0.79, respectively). Robust produced the highest grain yield (363.1 g/msuperscript 2). There were significant differences among cultivars in harvest index which was also correlated with grain yield (r = 0.41). Thus, differences in preheading and postheading growth traits among barley cultivars are highly associated with yield and may be useful for grain yield improvement. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of pattern of water supply on Vicia faba L. 2. Pod retention and filling, and dry matter partitioning, production and water use.
Authors: Grashoff C.
Published: June 2020

Pod retention and pod filling of V. faba was studied under different patterns of water supply. Mild water shortage during flowering, followed by plenty of water after flowering (d-i), resulted in high seed yields at lower stem nodes (defined as the first podding node to node number 11) in cv. Alfred. The inverse treatment (i-d: plenty of water during flowering, followed by increasing water shortage after flowering), but also i-i (plenty of water during and after flowering), showed 20-60% lower seed yields at those nodes. This effect was mainly due to a lower number of pods per node. In i-i, but not in i-d, the low pod retention at lower nodes was compensated for at higher nodes (defined as from node 12 to the last podding node). These results helped to explain the mechanism of the interaction between water supply pattern and the development of reproductive sinks. The quantitative consequences of these effects on the relation between total water use and seed yield are discussed. Without taking into account different water supply patterns, a linear relation between total water use (represented by total DM production) and seed yield already explained 75-85% of the variation in seed yield. If different water supply patterns were included in the regression analysis, >90% of the variation in seed yield could be explained. The i-i patterns, compared with d-i, resulted in suboptimum DM partitioning to reproductive organs, but showed a smaller seed yield variability. This indicated that defining and maintaining the optimum level of (mild) water shortage under varying climatological conditions needed further attention. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Ammonia volatilization from arable land after application of cattle slurry. 1. Field estimates.
Authors: Molen J. van der , Faassen H.G. van , Leclerc M.Y. , Vriesema R. , Chardon W.J.
Published: June 2020

Cattle slurry was surface-applied to bare soil in two experiments in September-November 1987, while in April-May 1988 two experiments were carried out in which the slurry was mixed with the upper 6 cm of the soil with a cultivator immediately after spreading. The 1987 experiments both lasted 18 days, the 1988 experiments 9 days. A micrometeorological technique, which did not disturb the dynamics of the air flow, was used to measure NH3 volatilization. Volatilization losses were also determined indirectly from mineral-N contents of soil-slurry samples collected at intervals after application. Diurnal fluctuations in the NH3 flux occurred throughout the experimental period, with maxima around midday and minima at midnight. The magnitude of the daily flux values decreased with time. The amounts of N lost through volatilization from surface-applied cattle slurry were 18 and 33% of the total N, resp., during the first 9 days, corresponding to 32 and 67% of the ammoniacal N applied with the slurry. Volatilization was negligible after day 9. Incorporation of the slurry into the soil considerably decreased the loss of N through volatilization: volatile losses of N after 9 days amounted to 6 and 7% of the total N, which corresponds to 11 and 16% of the ammoniacal N applied with the slurry. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Simulation of dry matter production and distribution in cassava (Manihot esculenta Crantz).
Authors: Gijzen H. , Veltkamp H.J. , Goudriaan J. , Bruijn G.H. de
Published: June 2020

The DM production of a number of cassava cultivars was simulated with a modified version of the SUCROS model. The overall behaviour of the model was validated with data from periodic harvests. The costs of maintenance respiration of stems and leaves were adjusted by curve fitting using data from one of the experiments. Agreement between experimental and model results was generally good. The model describes basic physiological processes and can be used to simulate growth of different cultivars in various climates. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Shrinkage of Dutch clay soil aggregates.
Authors: Bronswijk J.J.B. , Evers-Vermeer J.J.
Published: June 2020

Shrinkage characteristics and COLE and PLE values of undisturbed natural aggregates of clay soils from the Netherlands were measured. The course of the shrinkage process upon drying varied strongly between soils, and very often the measured characteristics diverged from the theoretical curve. Some Dutch clay soils are amongst the strongest swelling and shrinking soils in the world, with volume decreases of aggregates up to 49% between saturation and oven-dryness, and 42% between saturation and a pressure head of -16 000 cm. Potential subsidence of a Dutch field soil due to shrinkage is up to 15 cm. In some Netherlands clay soil, as a result of normal shrinkage, the aggregates remain saturated throughout the whole year; only inter-aggregate pores such as shrinkage cracks, contain air. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Statistical analysis and simulation modelling of the belowground food webs of two winter wheat management practices.
Authors: Moore J.C. , Zwetsloot H.J.C. , Ruiter P.C. de
Published: June 2020

Soil food webs from conventional and integrated management practices at an experimental site (Netherlands) were analysed using multivariate statistical procedures and simulation modelling, so as to identify patterns in species interactions and material transfers. Cluster analysis, canonical discriminant analysis and canonical correspondence analysis of the dynamics of biomass-N of functional groups within the food webs indicated that the webs could be compartmented into functional groups based on food choice and trophic level. The degree of compartmentalization depended on management practice. Consumers of fungi were separated in time from consumers of bacteria under the integrated management practice whereas little separation was observed under conventional practice. Simulation modelling was used to estimate the flux rates of nitrogen among functional groups within the food webs. The modelling demonstrated that more flow occurred in the integrated plot than in the conventional plot. More material flow occurred in the upper 10 cm of the integrated plot than in the 10-25 cm layer, whereas there was no such difference in the conventional plot. The effect may be due to the differences in the tillage practice on each plot. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Heavy metals and organic micropollutants in floodplains of the river Waal, a distributary of the river Rhine, 1958-1981.
Authors: Japenga J. , Zschuppe K.H. , Groot A.J. de , Salomons W.
Published: June 2020

During periods of high water discharge, dyke-protected floodplains of the river Rhine in the Netherlands become inundated and suspended matter from the river settles out. In the last 30 years, floodplain top layers have been sampled several times just after deposition; samples were dried and stored in a specimen bank. The samples were used to assess the development of sediment contamination with heavy metals and organic micropollutants during the past decades. Heavy metals studied include Zn, Cu, Cr, Pb, Cd, Ni, Hg and As. Different groups of chemically persistent organic micropollutants were studied: polycyclic aromatic hydrocarbons, polychlorobiphenyls, hexachlorobenzene, DDT and DDT-metabolites. The levels of most contaminants decreased substantially between 1958 and 1981. The variation among the different floodplain locations is due to differences in hydrodynamic characteristics of the location. A comparison was made between the concentrations found and the levels considered acceptable if the floodplain area is used for cattle grazing; a comparison was also made with estimated natural background levels and with reference values defined by the Dutch government. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Digestibility of grass silage.
Authors: Steg A. , Spoelstra S.F. , Meer J.M. van der , Hindle V.A.
Published: June 2020

A total of 50 grass silages were tested in digestibility trials using Texel wethers. The feed silages were wilted of varying DM contents and treated with cell-wall degrading enzymes. The accuracy of feed evaluation was studied using laboratory analyses, including cell-wall analyses, incubation in vitro with rumen fluid and the enzymic procedure. A comparison was made between these results and the current and recently suggested procedures for prediction of digestibility of grass silage. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effects of pattern of concentrate feeding on milk production of dairy cows offered silage ad libitum.
Authors: Rijpkema Y.S. , Reeuwijk L. van , Goedhart P.W.
Published: June 2020

In three 24-wk experiments beginning at wk 4 post partum, a system of concentrate feeding at a flat level was compared with feeding concentrates to milk yield (experiments 1 and 2), or with a high-low 2-step system in which the rate was reduced after wk 12 (experiment 3). Roughage was offered ad lib. In experiment 1 two types of concentrates were involved whereas in experiment 3 two levels of concentrates were applied. The systems were evaluated using high levels of concentrates and with Friesian and Holstein-Friesian cows producing about 7000 kg milk/lactation. Experiments 1 and 3 involved 64 and experiment 2 32 cows. In the comparison between feeding strategies, differences in yield and composition of milk were of minor importance except for milk protein content on the moderate-quality grass silage diet (experiment 1). Milk production tended to be higher for concentrates including fish meal, in contrast to soyabean meal, particularly in the first half of the experimental period. However, milk fat content was significantly lower, resulting in similar productions of 4%-FCM. Extra concentrates in experiment 3 had significant positive effects on the production of milk, fat and protein, and also on milk protein content and liveweight gain. Feeding strategy however, was without any significant effect. It was concluded that with the high-yielding cows, offered roughages to appetite, there is no need to feed concentrates strictly to their estimated individual energy requirements. This may be of increasing importance when forage allowances/cow increase as a consequence of smaller numbers of cows/farm. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Ruminal behaviour of structural carbohydrates, non-structural carbohydrates and crude protein from concentrate ingredients in dairy cows.
Authors: Tamminga S. , Vuuren A.M. van , Koelen C.J. van der , Ketelaar R.S. , Togt P.L. van der
Published: June 2020

Ruminal degradation characteristics of neutral detergent fibre (NDF), starch and crude protein (CP) in concentrate ingredients were estimated in dairy cows using nylon bag incubations. Soluble fraction (starch, CP), undegradable fraction (NDF, CP), lag time (NDF) and rate of degradation of the insoluble but degradable fraction (NDF, starch, CP) were measured and showed large variation. Based on measured and partly estimated characteristics ratio's were calculated between total rumen available CP and carbohydrates, between soluble CP and soluble carbohydrates and between insoluble rumen available CP and insoluble rumen available carbohydrates. Ratio's varied largely between feeds and between soluble and insoluble fractions. It is concluded that such ratio's can be used to optimize the composition of concentrates with regard to rumen fermentation. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Feeding strategy during pregnancy for ewes with a large litter size. 1. Effect of quantity and composition of concentrates on intake and reproductive performance.
Authors: Everts H.
Published: June 2020

In 6 trials, 40 Ile de France X Finnish Landrace ewes 2 to 8 years old were given during pregnancy diets containing 40% energy from concentrates and crude protein (CP) 196 or 91 g/kg or 60% energy from concentrates and CP 189 or 240 g/kg. Mean litter size was 3.26. The sum of the birth weights of lambs was affected by the treatment where a higher protein concentration was combined with a lower degradability of the protein. Net body weight gain was affected by litter size, ketosis and treatment. Metabolizable energy (ME) intake was lower than expected. Treatments with 60% of energy from concentrates showed a higher ME intake than treatments with 40% of energy originating from concentrates. CP intake was higher where a higher protein level was combined with a lower degradability. DM intake in the last 2 months of pregnancy was affected by litter size, age of the ewes, ketosis and feeding treatment. DM intake decreased in the last weeks of pregnancy and was related to litter size, The possible reasons for this effect are discussed. Substitution rates of concentrates to forage depended also on the litter size. The effect of the ketosis on the intake pattern is described. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Feeding strategy during pregnancy for ewes with a large litter size. 2. Effect on blood parameters and energy status.
Authors: Everts H.
Published: June 2020

In 6 feeding trials with pregnant ewes, blood glucose concentrations were affected by litter size after day 84 of pregnancy. An increase in litter size decreased blood glucose during the last phase of pregnancy. At day 141 a sharp increase in glucose was seen. Ewes with ketosis had after day 126 of pregnancy a significant lower glucose concentration. beta -Hydroxybutyrate (BHB) and non-esterified fatty acids (NEFA) were also affected by litter size in the last months of pregnancy. With increasing litter size BHB increased more dramatically than NEFA concentrations. Ewes with ketosis had higher BHB and NEFA concentrations in the last month of pregnancy. Ewes on treatments with a higher metabolizable energy (ME) intake (rations with 60% of the energy originating from concentrates) had a higher glucose, a lower BHB and a lower NEFA concentration in the last month of pregnancy than ewes given a diet with 40% of the energy originating from concentrates. A lower incidence of ketosis on treatments with a higher energy intake was expected, but not seen. Probably, energy deficit is not the only factor inducing ketosis. With regression models the energy requirement of pregnant ewes with a body weight of about 85 kg during the last month of pregnancy was estimated. ME requirement in MJ per day for a ewe with a single, twin, triplet, quadruplet and quintuplet was 13.0, 15.9, 17.1, 18.4 and 19.1, respectively. The estimated energetic efficiency of conceptus growth was about 0.16. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A comparison of different techniques to assess the biological availability of feed phosphates in pig feeding.
Authors: Dellaert B.M. , Peet G.F.V. van der , Jongbloed A.W. , Beers S.
Published: June 2020

Piglets from about 6 weeks old were fed on basal diets with P 0, 0.6, 1.2 or 1.8 g/kg, 0, 1.2 or 2.2 g/kg, and 0 or 2.0 g/kg in experiments 1, 2 and 3, respectively. Blood factors did not show a significant response to P intake. Plasma alkaline phosphatase activity was not linearly related to P intake, while regressing the inorganic P content to the quantity of supplemented P resulted in a low fitness of the model (Rsuperscript 2 = 53%). Results from bone fat-free DM, concentration of ash in fat-free DM, amount of ash, concentration of P in ash and bone breaking strength were better (Rsuperscript 2 = 45 to 94%). There were slight differences in the results using tibia, femur or third and fourth metatarsals. However, the highest degree of fit was found using the apparent digestibility of P as the dependent variable (Rsuperscript 2 = 96 to 100%). After relating the criteria to the retention of P, again the apparent P digestibility was the most accurate factor to determine the biological availability of P. Basing the nutritional value of feed phosphates on digestibility of P, significant differences were shown between form and origin of feed phosphate. The values within a type of feed phosphate showed a high repeatability. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Amino acid requirements of pigs. 1. Requirements for methionine + cystine, threonine and tryptophan of fast-growing boars and gilts, fed ad libitum.
Authors: Lenis N.P. , Diepen J.T.M. van , Goedhart P.W.
Published: June 2020

In 3 experiments each of 4 treatments, crossbred pigs about 35 kg were given basal diets with a low concentration of 1 amino acid and DL methionine 0, 0.41 or 0.82 and 1.23, L-threonine 0, 0.5, 1.0 and 1.5 and DL-tryptophan 0, 0.31, 0.62 and 0.93 g/kg. Apparent faecal digestibility of organic matter, protein and amino acids of 1 or 2 diets from each feeding experiment was estimated with 4 pigs each. Average daily gain of the optimally supplemented groups was 875 g and feed conversion ratio 2.84. For maximum growth performance of pigs between 35 and 105 kg, the requirement for total methionine + cystine, threonine and tryptophan, relative to total lysine supply, was about 60, 66 and 19%, respectively. On a faecal digestible basis, requirements were about 58, 63 and 19%, relative to faecal digestible lysine, respectively. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Processing methods for feather meal and aspects of quality.
Authors: Poel A.F.B. van der , El-Boushy A.R.
Published: June 2020

This overview covers processing equipment and possible quality control parameters with respect to the thermal processing of feathers. The final quality of feather meal depends mainly on the time/pressure (temperature) pattern during hydrolysation of feathers, arising from legal requirements for sterilization. Some aspects of feather meal quality are discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The precision in estimating the stem volume in Smilde forest management unit.
Authors: Jansen J.J.
Published: June 2020

An estimate was made of the volume of the growing stock of the 1800 ha Smilde forest management unit, Netherlands using double (or two-phase) sampling. A systematic sample scheme was used to estimate the number of trees per diameter class in phase 1. In phase 2, the relation between diameter and volume was calculated using linear regression. The total volume was estimated at 140.5+or-8.0msuperscript 3/ha. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Factors affecting the requirement of dietary sulphur-containing amino acids of young pigs.
Authors: Schutte J.B. , Bosch M.W. , Jong J. de , Weerden E.J. van , Koch F.
Published: June 2020

In the first of 3 experiments, requirement for total and digestible sulphur amino acids (SAA) was estimated in 240 pigs, 14 to 40 kg. A diet with low digestible amino acids content (digestible sulphur amino acids (SAA) 0.37%) was supplemented with all essential amino acids except methionine and 0, 0.05, 0.1, 0.1 or 0.2% synthetic DL-methionine added, providing diets with 0.42, 0.47, 0.52 and 0.57% digestible SAA. A control diet contained 0.52% digestible SAA. At similar levels of digestible SAA, there was no difference in performance between the experimental and the control diet, showing that optimum performance can be obtained with a less digestible diet supplemented with essential amino acids. Optimum performance was at 0.52% digestible SAA content in the diet, corresponding to about 0.65% total SAA. In experiment 2, 360 pigs 15 to 40 kg, were used to study SAA requirement at sub-optimal (0.60%) and optimal (0.70%) dietary threonine levels. Increasing threonine from 0.60 to 0.70%, increased (P
Experiments to predict the response of thematic mapper bands 3, 4 and 5 to grass drought.
Authors: Mulders M.A. , Logchem A. van
Published: June 2020

Turf samples 60cm x30 cm and 10 cm deep from 3 locations in NE Netherlands showed a range of grass and soil types. During a drying period in the laboratory, reflectance measurements were carried out and moisture contents of grass and soil were estimated. The soil moisture contents were converted to pF values. The narrow band values of the laboratory measurements on reflectance were added to compose broad Thematic Mapper bands. Multiple linear regression on the experimental results produced equations with grass moisture, soil moisture and pF as dependent variables. These variables could be estimated from reflectance values in the TM bands 3, 4 and 5 with respective standard errors of 13.8-16.0%, 8.5% and 0.1%. The pattern of TM satellite data of grassland at one specific acquisition date revealed that it is very likely that remote sensing data could be used to detect drought phenomena, although field observations would still be required. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of grassland management on the amounts of soil organic N and C.
Authors: Hassink J. , Neeteson J.J.
Published: June 2020

The effects of different management systems on soil organic N and C contents were studied on a sandy and loamy soil given various amounts of N fertilizers under rotational grazing, in the Netherlands. Differences in total soil N and C between grazed and mown fields were also investigated. On the loamy soil grazed plots N accumulated at 245 kg/ha per year, irrespective of the rate of applied N. Four years after the experiment was initiated both soil N and C contents were considerably higher under grazing than under mowing. The C/N ratio of soil organic matter was higher without N fertilizer application, especially in the top 5 cm. The amount of N returned to the soil by grazing was 71% and 57% in the sandy and the loamy soil, resp. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The control of sigatoka (banana leaf spot disease) by mist-blowing with Banacobre-Sandoz.
Authors: Tollenaar D.
Published: June 2020

In Ecuador a special mist blower was constructed with a pipe 8 1/2 m. high, at the top of which were 6 downward-pointing outlets. A 3 % solution of Banacobre-Sandoz (a cuprous oxide with a sticker) was blown down on the upper leaf surfaces of banana rows on each side. The droplet size was 50-100 mu . Satisfactory control of banana leaf spot was obtained by using 100 1. spray per ha., in regular 3- or 4-weekly cycles from the beginning of January. Fruit washing was not necessary after using this spray. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The genesis and classification of mountain soils developed on tuffs in Indonesia.
Authors: Van Schuylenborgh J. , Van Rummelen F.F.F.E.
Published: June 2020

Profile characteristics and analytical data of the soils occurring at 600-2000 m altitudes under humid tropical conditions show a predominant influence of the parent material. Brown podzolic soils are formed on liparitic tuffs, grey-brown podzolic soils on andesitic tuffs and brown forest soils on basalto-andesitic tuffs. These "tropical grey-brown podzolic" and "tropical brown forest" soils with clay minerals of the 1: 1 type crystal lattice seem to be formed by rapid weathering under the influence of CO2-containing water, in contrast to the more intensive but less rapid weathering of similar soils in the temperate zones of America (2: 1 type crystal lattice) under the influence of relatively high concentrations of organic acids. The difference in weathering accounts for the greater mobility of Al than of Fe under tropical conditions. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Soil heterogeneity and soil testing.
Authors: Ferrari T.J. , Vermeulen F.H.B.
Published: June 2020

The error of analysis is generally small. The standard deviation influenced by analysis and sampling averages 10% in P, K and Mg determinations. The error in pH value is approximately 0.1 per unit. There is little difference between grassland and arable land or between various types of soil in this respect; the size of the field has, on the average, no effect on the magnitude of sampling error. If it is desired to compare results of samplings of the same field taken in certain intervals, changes due to climate, farming operations, etc. have to be taken into consideration. The longer a field is under observation, the greater will be the significance and value of soil testing.- From authors' summary. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effects of competition with weeds on growth, development and yield of groundnuts.
Authors: Everaarts A.P.
Published: June 2020

Competition between weeds and groundnuts was studied in two field experiments in the inland Zanderij area of Suriname. The crop was kept weed-free or without weed control for increasing periods of time after planting. Observations made at the end of each period with or without weed control provided an analysis of the growth of a crop with weed control and of a crop without weed control. Uncontrolled weed growth was concentrated between the rows. Competition with weeds reduced ground cover and LAI of the crop. DM accumulation was affected, resulting in lower yields. Plant density and number of branches per plant were not influenced. Weed competition increased stem length and reduced the number of leaves and pods per plant. Timing of flowering was not influenced. Competition for nutrients was absent, but there was competition for light and water. About 15 weed-free days after planting were sufficient to prevent yield losses. Yield losses were due to a reduction in number of pods per plant. Competition should especially be prevented in the period when the number of pods per plant is established, i.e. around 35-60 days after planting. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effects of lighting regimen on metabolic rate in broilers.
Authors: Heetkamp M.J.W. , Henken A.M. , Hel W. van der , Scheele C.W.
Published: June 2020

From hatching to 42 days old, 80 broilers were exposed to varying periods of light (L) and dark (D) within 4-h periods (0.5L to 1.5L and 3.5D to 2.5D). Effects of lighting regimen (LR) and trough position (open (F2) compared with closed (F1)) during D-periods on heat production (H), activity-free (Hacf) and activity-related H (Hac), and respiratory quotient (RQ) were evaluated. At 0.5L and 0.67L, Hac was less than in the longer L-periods. The longer the L-period, the less active broilers were at the end of a L-period. In D-periods with F1, H and Hacf decreased more than with F2, while Hac was similar. After D-periods with F1, H and Hacf increased more than after D-periods with F2. This effect on H was greatest in short L-periods with F1. With 0.5L:3.5D and F1, broilers did not have enough feeding time, because at the end of the L-period afterwards, H and RQ were lower than with the longer L-periods. Thus, broilers will eat feed in the dark and the length of L-period may not be crucial, because in practice, feed will remain available in the dark. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Advancing growth vigour of seed potatoes by storage temperature regimes
Authors: Van Ittersum M.K.
Published: June 2020

In a field trial in the Negev, Israel, and 2 greenhouse trials in Wageningen, Netherlands, in 1989, potato cultivars with different dormancy periods were stored at a constant 18 degrees C, a constant 28 degrees, 20 d at 28 degrees and subsequently at 18 degrees (10 d at 0 degrees, 10 d at 28 degrees and subsequently at 18 degrees in 1 experiment), or 20 d at 2 degrees and subsequently at 18 degrees. In all but 1 cultivar storage at 28 degrees gave superior growth vigour (earlier emergence, more stems/tuber, faster initial growth and earlier tuber initiation) at early plantings (less or =120 d after haulm removal (DAH)) than the other storage regimes. However, this treatment was detrimental to cultivars such as Draga with a long dormancy period and a rapid rate of physiological aging. Growth vigour was also advanced by hot or cold pretreatment, and was lowest with storage at 18 degrees. At later plantings (up to 180 DAH), the differences between the regimes decreased.