Leon de jonge

Leon de jonge
Wageningen University & Research | WUR · Department of Animal Nutrition

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32
Publications
6,304
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404
Citations
Citations since 2016
2 Research Items
189 Citations
201620172018201920202021202205101520253035
201620172018201920202021202205101520253035
201620172018201920202021202205101520253035
201620172018201920202021202205101520253035

Publications

Publications (32)
Article
In een onderzoek naar de voederwaarde en diervoedergrondstoffen, uitgevoerd door Wageningen Livestock Research in samenwerkin met Schothorst Feed Research, zijn een grote verschillen in verteerbaarheid van nutriënten gevonden tussen biologisch gehouden varkens te verbeteren kan intrinsiek fytase uit tarwe en tarwegries een uitkomst bieden.
Article
The objective of this study was to investigate the effects of increasing maturity of whole-plant corn at harvest on CH4 emissions by dairy cows consuming corn silage (CS) based diets. Whole-plant corn was harvested at a very early [25% dry matter (DM); CS25], early (28% DM; CS28), medium (32% DM; CS32), and late (40% DM; CS40) stage of maturity. In...
Article
Full-text available
The in situ degradation of the washout fraction of starch in six feed ingredients (i.e. barley, faba beans, maize, oats, peas and wheat) was studied by using a modified in situ protocol and in vitro measurements. In comparison with the washing machine method, the modified protocol comprises a milder rinsing method to reduce particulate loss during...
Article
In in situ nylon bag technique, many feed evaluation systems use a washing machine method (WMM) to determine the washout (W) fraction and to wash the rumen incubated nylon bags. As this method has some disadvantages, an alternate modified method (MM) was recently introduced. The aim of this study was to determine and compare the W and non-washout (...
Article
Full-text available
In the classic in situ method, small particles are removed during rinsing and hence their fractional degradation rate cannot be determined. A new approach was developed to estimate the fractional degradation rate of nutrients in small particles. This approach was based on an alternative rinsing method to reduce the particulate matter loss during ri...
Article
Full-text available
The objective of this experiment was to evaluate interaction effects between stage of maturity and nitrogen (N) fertilisation rate on rumen degradation characteristics determined with nylon bag incubations of ryegrass herbages and ryegrass silage. Grass herbage (n = 4) was cut after 3 or 5 weeks of regrowth and received a low (20 kg N/ha) or a high...
Article
Full-text available
A modified rinsing method for the in situ technique was developed to separate, isolate and characterise the soluble (S), the insoluble washout (W-S) and the non-washout fractions (D + U) within one procedure. For non-incubated bags (t = 0 h), this method was compared with the conventional, Combined Fractionation (CF) method that measures the D + U...
Book
Full-text available
Full document can be downloaded from: http://www.fao.org/docrep/019/i3535e/i3535e.pdf
Book
Full publication can be downloaded from: http://www.fao.org/docrep/019/i3535e/i3535e.pdf
Book
Full document can be downloaded from: http://www.fao.org/docrep/019/i3535e/i3535e.pdf
Book
Setting up a feed analysis laboratory, and implementing a quality assurance system compliant with ISO/IEC 17025:2005
Article
Three experiments were conducted to evaluate the effects of temperature (T), pH, time of incubation and pepsin on the stability of intrinsic phytase of different cereals. Experiment one was conducted as a 3×4×3×3 factorial arrangement with three feed ingredients (rye, wheat and barley), four T (20, 38, 55 and 80 °C), three pH levels (3.0, 5.5 and 8...
Article
Solubility of N is an important parameter in many protein evaluation systems for ruminants. The influence of different rumen conditions, such as pH, osmolality and temperature of solvents, on solubility of N compounds in various animal feed ingredients was examined in two experiments. In the first experiment, 17 feedstuffs were evaluated including...
Article
Full-text available
The objective of this study was to examine the ruminal biohydrogenation of linoleic (18:2n-6) and linolenic (18:3n-3) acid during in vitro incubations with rumen inoculum from dairy cattle adapted or not to marine algae and with or without additional in vitro docosahexaenoic acid (DHA, 22:6n-3) supplementation. Treatments were incubated in 100-mL f...
Article
Het CVB van het Productschap Diervoeder heeft het eiwitwaarderingsysteem uit 1991 in 2007 herzien. Daarvoor zijn van diverse voedermiddelen aanvullende analyses gedaan om tot betrouwbare rekenregels te komen. Voor vers gras is aanvullend onderzoek gedaan naar de oplosbare en uitwasbare fractie van ruw eiwit. In het DVE/OEB- 2007 systeem worden die...
Article
The interaction between protein and phytate was investigated in vitro using proteins extracted from five common feedstuffs and from casein. The appearance of naturally present soluble protein-phytate complexes in the feedstuffs, the formation of complexes at different pHs, and the degradation of these complexes by pepsin and/or phytase were studied...
Article
The (water)-soluble fraction of feeds is often assumed to be completely and immediately degraded in the rumen. The objective of this study was to separate the washout fraction (fraction A) obtained usually by difference after submitting the nylon bags to the machine-washing program, to investigate the nature and the degradation of the soluble crude...
Article
A (31)P NMR method for quantitative determination of inositol phosphates in simple incubation samples of sodium phytate and Aspergillus niger phytase and in different types of complex samples, such as diets, digesta, and feces, is described. The inositol phosphates in complex samples were extracted with HCl, concentrated, and purified using freeze-...
Article
Three factors contributing to inter-laboratory variation in the determination of amino acids in plasma, i.e. deproteinization, calibration and storage conditions, were evaluated in this study. Deproteinization clearly enlarged the coefficient of variation in the determination of cystine, aspartic acid and tryptophan. During this process losses of h...
Article
Determination of amino acids in pig plasma with the classical ninhydrin system is influenced by the excessive amount of protein and lipophilic compounds in the sample, leading to a decline in resolution. This problem was eliminated by using 80 mg of sulphosalicylic acid per ml of plasma, and solid-phase extraction with a C18 cartridge as an additio...
Article
Sampling in site investigations is mostly done on the basis of hit or miss probing. Several mathematical and (geo)statistical methods are available for improving the reliability of sampling procedures. Combining these tools with the knowledge of experts in a so-called soft-knowledge based computer program is an excellent way of rationalizing sampli...

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