J.W. Spek

1.0k total citations
18 papers, 726 citations indexed

About

J.W. Spek is a scholar working on Agronomy and Crop Science, Animal Science and Zoology and Environmental Chemistry. According to data from OpenAlex, J.W. Spek has authored 18 papers receiving a total of 726 indexed citations (citations by other indexed papers that have themselves been cited), including 13 papers in Agronomy and Crop Science, 9 papers in Animal Science and Zoology and 6 papers in Environmental Chemistry. Recurrent topics in J.W. Spek's work include Ruminant Nutrition and Digestive Physiology (13 papers), Reproductive Physiology in Livestock (7 papers) and Animal Nutrition and Physiology (5 papers). J.W. Spek is often cited by papers focused on Ruminant Nutrition and Digestive Physiology (13 papers), Reproductive Physiology in Livestock (7 papers) and Animal Nutrition and Physiology (5 papers). J.W. Spek collaborates with scholars based in Netherlands, Belgium and Canada. J.W. Spek's co-authors include J. Dijkstra, A. Bannink, Jan Willem van Groenigen, A.M. van Vuuren, O. Oenema, G. van Duinkerken, W.H. Hendriks, Gerrit Gort, M.M. van Krimpen and R. Martineau and has published in prestigious journals such as Journal of Dairy Science, Poultry Science and Animal Feed Science and Technology.

In The Last Decade

J.W. Spek

17 papers receiving 710 citations

Peers — A (Enhanced Table)

Peers by citation overlap · career bar shows stage (early→late) cites · hero ref

Name h Career Trend Papers Cites
J.W. Spek Netherlands 11 517 179 164 156 133 18 726
E. K. Okine Canada 17 680 1.3× 145 0.8× 175 1.1× 73 0.5× 153 1.2× 38 891
M.J. Aguerre United States 14 617 1.2× 196 1.1× 151 0.9× 82 0.5× 207 1.6× 31 802
V. A. Wilkerson United States 9 378 0.7× 142 0.8× 112 0.7× 95 0.6× 109 0.8× 12 489
Danny G. Fox United States 17 584 1.1× 324 1.8× 288 1.8× 108 0.7× 166 1.2× 32 909
Daniel Sauvant France 16 639 1.2× 274 1.5× 269 1.6× 86 0.6× 85 0.6× 49 950
P. Huhtanen Finland 15 950 1.8× 443 2.5× 169 1.0× 145 0.9× 128 1.0× 26 1.1k
Maike Brask Denmark 10 493 1.0× 110 0.6× 98 0.6× 42 0.3× 168 1.3× 13 608
M. Doreau France 6 648 1.3× 148 0.8× 163 1.0× 29 0.2× 266 2.0× 9 833
Henrique Mendonça Nunes Ribeiro Filho Brazil 16 645 1.2× 191 1.1× 117 0.7× 62 0.4× 126 0.9× 65 794
Jessie Guyader Germany 13 578 1.1× 90 0.5× 116 0.7× 40 0.3× 120 0.9× 24 702

Countries citing papers authored by J.W. Spek

Since Specialization
Citations

This map shows the geographic impact of J.W. Spek's research. It shows the number of citations coming from papers published by authors working in each country. You can also color the map by specialization and compare the number of citations received by J.W. Spek with the expected number of citations based on a country's size and research output (numbers larger than one mean the country cites J.W. Spek more than expected).

Fields of papers citing papers by J.W. Spek

Since Specialization
Physical SciencesHealth SciencesLife SciencesSocial Sciences

This network shows the impact of papers produced by J.W. Spek. Nodes represent research fields, and links connect fields that are likely to share authors. Colored nodes show fields that tend to cite the papers produced by J.W. Spek. The network helps show where J.W. Spek may publish in the future.

Co-authorship network of co-authors of J.W. Spek

This figure shows the co-authorship network connecting the top 25 collaborators of J.W. Spek. A scholar is included among the top collaborators of J.W. Spek based on the total number of citations received by their joint publications. Widths of edges represent the number of papers authors have co-authored together. Node borders signify the number of papers an author published with J.W. Spek. J.W. Spek is excluded from the visualization to improve readability, since they are connected to all nodes in the network.

All Works

18 of 18 papers shown
1.
Harn, J. van, J.W. Spek, & P. Bikker. (2025). Pre-cecal calcium digestibility of eggshell products in broilers. Poultry Science. 104(6). 105090–105090.
2.
Goethals, Sofie, et al.. (2024). Lysine requirement of weaned piglets. animal. 19(1). 101323–101323. 2 indexed citations
3.
Lapierre, H., R. Martineau, M.D. Hanigan, et al.. (2020). Review: Impact of protein and energy supply on the fate of amino acids from absorption to milk protein in dairy cows. animal. 14(S1). s87–s102. 35 indexed citations
4.
Spek, J.W., et al.. (2020). Development of equations to estimate microbial nitrogen contamination in rumen incubation residues using 15N data and chemical composition of feedstuffs. Animal Feed Science and Technology. 273. 114798–114798. 2 indexed citations
5.
Harn, J. van, et al.. (2017). Determination of pre-cecal phosphorus digestibility of inorganic phosphates and bone meal products in broilers. Poultry Science. 96(5). 1334–1340. 21 indexed citations
6.
Lapierre, H., D.R. Ouellet, R. Martineau, & J.W. Spek. (2016). Key Roles of Amino Acids In Cow Performance and Metabolism – Considerations For Defining Amino Acid Requirements. eCommons (Cornell University). 5 indexed citations
7.
Spek, J.W., J. Dijkstra, & A. Bannink. (2016). Influence of milk urea concentration on fractional urea disappearance rate from milk to blood plasma in dairy cows. Journal of Dairy Science. 99(5). 3880–3888. 12 indexed citations
8.
Bikker, P., J.W. Spek, R.A. van Emous, & M.M. van Krimpen. (2016). Precaecal phosphorus digestibility of inorganic phosphate sources in male broilers. British Poultry Science. 57(6). 810–817. 18 indexed citations
9.
Duinkerken, G. van, J.W. Cone, A. Klop, et al.. (2014). Relationship between chemical composition and in situ rumen degradation characteristics of maize silages in dairy cows. animal. 8(11). 1832–1838. 11 indexed citations
10.
Spek, J.W., J. Dijkstra, G. van Duinkerken, W.H. Hendriks, & A. Bannink. (2013). Prediction of urinary nitrogen and urinary urea nitrogen excretion by lactating dairy cattle in northwestern Europe and North America: A meta-analysis. Journal of Dairy Science. 96(7). 4310–4322. 87 indexed citations
11.
Dijkstra, J., O. Oenema, Jan Willem van Groenigen, et al.. (2013). Diet effects on urine composition of cattle and N2O emissions. animal. 7. 292–302. 301 indexed citations
12.
Spek, J.W., A. Bannink, Gerrit Gort, W.H. Hendriks, & J. Dijkstra. (2013). Interaction between dietary content of protein and sodium chloride on milk urea concentration, urinary urea excretion, renal recycling of urea, and urea transfer to the gastrointestinal tract in dairy cows. Journal of Dairy Science. 96(9). 5734–5745. 29 indexed citations
13.
Bannink, A., J.L. Ellis, Núria Mach, J.W. Spek, & J. Dijkstra. (2013). Interactions between enteric methane and nitrogen excretion in dairy cows. Advances in Animal Biosciences. 4. 19–27. 5 indexed citations
14.
Spek, J.W., J. Dijkstra, J.J.G.C. van den Borne, & A. Bannink. (2012). Short communication: Assessing urea transport from milk to blood in dairy cows. Journal of Dairy Science. 95(11). 6536–6541. 8 indexed citations
15.
Spek, J.W., A. Bannink, Gerrit Gort, W.H. Hendriks, & J. Dijkstra. (2012). Effect of sodium chloride intake on urine volume, urinary urea excretion, and milk urea concentration in lactating dairy cattle. Journal of Dairy Science. 95(12). 7288–7298. 52 indexed citations
16.
Spek, J.W., J. Dijkstra, G. van Duinkerken, & A. Bannink. (2012). A review of factors influencing milk urea concentration and its relationship with urinary urea excretion in lactating dairy cattle. The Journal of Agricultural Science. 151(3). 407–423. 110 indexed citations
17.
Spek, J.W., et al.. (2009). Effects of pH, temperature and osmolality on the level and composition of soluble N in feedstuffs for ruminants. Animal Feed Science and Technology. 153(3-4). 249–262. 19 indexed citations
18.
Spek, J.W., et al.. (1973). Seed transmission of Verticillium dahliae. 38(3). 1427–1434. 9 indexed citations

Rankless uses publication and citation data sourced from OpenAlex, an open and comprehensive bibliographic database. While OpenAlex provides broad and valuable coverage of the global research landscape, it—like all bibliographic datasets—has inherent limitations. These include incomplete records, variations in author disambiguation, differences in journal indexing, and delays in data updates. As a result, some metrics and network relationships displayed in Rankless may not fully capture the entirety of a scholar's output or impact.

Explore authors with similar magnitude of impact

Breakdown of academic impact, for papers by E. K. Okine Breakdown of academic impact, for papers by M.J. Aguerre Breakdown of academic impact, for papers by V. A. Wilkerson Breakdown of academic impact, for papers by Danny G. Fox Breakdown of academic impact, for papers by Daniel Sauvant Breakdown of academic impact, for papers by P. Huhtanen Breakdown of academic impact, for papers by Maike Brask Breakdown of academic impact, for papers by M. Doreau Breakdown of academic impact, for papers by Henrique Mendonça Nunes Ribeiro Filho Breakdown of academic impact, for papers by Jessie Guyader
Rankless by CCL
2026