Hostname: page-component-cd9895bd7-8ctnn Total loading time: 0 Render date: 2024-12-25T06:44:16.710Z Has data issue: false hasContentIssue false
  • English
  • Français

Update of the Dutch protein evaluation system for ruminants: the DVE/OEB2010 system

Published online by Cambridge University Press:  19 November 2010

G. VAN DUINKERKEN ,
M. C. BLOK ,
A. BANNINK ,
J. W. CONE ,
J. DIJKSTRA ,
A. M. VAN VUUREN  and
S. TAMMINGA
G. VAN DUINKERKEN*
Affiliation:
Wageningen UR Livestock Research, Edelhertweg 15, 8219 PH Lelystad, The Netherlands
M. C. BLOK
Affiliation:
Product Board Animal Feed, Stadhoudersplantsoen 12, 2517 JL The Hague, The Netherlands
A. BANNINK
Affiliation:
Wageningen UR Livestock Research, Edelhertweg 15, 8219 PH Lelystad, The Netherlands
J. W. CONE
Affiliation:
Animal Nutrition Group, Wageningen University, Marijkeweg 40, 6709 PG Wageningen, The Netherlands
J. DIJKSTRA
Affiliation:
Animal Nutrition Group, Wageningen University, Marijkeweg 40, 6709 PG Wageningen, The Netherlands
A. M. VAN VUUREN
Affiliation:
Wageningen UR Livestock Research, Edelhertweg 15, 8219 PH Lelystad, The Netherlands
S. TAMMINGA
Affiliation:
Animal Nutrition Group, Wageningen University, Marijkeweg 40, 6709 PG Wageningen, The Netherlands
*
*To whom all correspondence should be addressed. Email: [email protected]
Get access Rights & Permissions [Opens in a new window]

Summary

In the current Dutch protein evaluation system (the DVE/OEB1991 system), two characteristics are calculated for each feed: true protein digested in the intestine (DVE) and the rumen degradable protein balance (OEB). Of these, DVE represents the protein value of a feed, while OEB is the difference between the potential microbial protein synthesis (MPS) on the basis of available rumen degradable protein and that on the basis of available rumen degradable energy. DVE can be separated into three components: (i) feed crude protein undegraded in the rumen but digested in the small intestine, (ii) microbial true protein synthesized in the rumen and digested in the small intestine, and (iii) endogenous protein lost in the digestive processes.

Based on new research findings, the DVE/OEB1991 system has recently been updated to the DVE/OEB2010 system. More detail and differentiation is included concerning the representation of chemical components in feed, the rumen degradation characteristics of these components, the efficiency of MPS and the fractional passage rates. For each chemical component, the soluble, washout, potentially degradable and truly non-degradable fractions are defined with separate fractional degradation rates. Similarly, fractional passage rates for each of these fractions were identified and partly expressed as a function of fractional degradation rate. Efficiency of MPS is related to the various fractions of the chemical components and their associated fractional passage rates. Only minor changes were made with respect to the amount of DVE required for maintenance and production purposes of the animal. Differences from other current protein evaluation systems, viz. the Cornell Net Carbohydrate and Protein system and the Feed into Milk system, are discussed.

Type
Modelling Animal Systems
Information
The Journal of Agricultural Science , Volume 149 , Issue 3 , June 2011 , pp. 351 - 367
Copyright
Copyright © Cambridge University Press 2010

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Archimède, H., Sauvant, D. & Schmidely, P. (1997). Quantitative review of ruminal and total tract digestion of mixed diet organic matter and carbohydrates. Reproduction Nutrition Development 37, 173–189.CrossRefGoogle ScholarPubMed
Bach, A., Calsamiglia, S. & Stern, M. D. (2005). Nitrogen metabolism in the rumen. Journal of Dairy Science 88 (E suppl.), E9–E21.CrossRefGoogle ScholarPubMed
Bannink, A. (2007). Modelling volatile fatty acid dynamics and rumen function in lactating cows. Ph.D. Thesis, Wageningen University, The Netherlands.Google Scholar
Bosch, M. W., Tamminga, S., Post, G., Leffering, C. P. & Muylaert, J. M. (1992). Influence of stage of maturity of grass silages on digestion processes in dairy cows. 1. Composition, nylon bag degradation rates, fermentation characteristics, digestibility and intake. Livestock Production Science 32, 245–264.CrossRefGoogle Scholar
Broderick, G. A., Satter, L. D. & Harper, A. E. (1974). Use of plasma amino acid concentration to identify limiting amino acids for milk production. Journal of Dairy Science 57, 1015–1023.CrossRefGoogle Scholar
Broderick, G. A., Stevenson, M. J., Patton, R. A., Lobos, N. E. & Olmos Colmenero, J. J. (2008). Effect of supplementing rumen-protected methionine on production and nitrogen excretion in lactating dairy cows. Journal of Dairy Science 91, 1092–1102.CrossRefGoogle ScholarPubMed
Burgos, S. A., Fadel, J. G. & DePeters, E. J. (2007). Prediction of ammonia emission from dairy cattle manure based on milk urea nitrogen: relation of milk urea nitrogen to urine urea nitrogen excretion. Journal of Dairy Science 90, 5499–5509.CrossRefGoogle ScholarPubMed
Cabrita, A. R. J., Dewhurst, R. J., Abreau, J. M. F. & Fonseca, A. J. M. (2006). Evaluation of the effects of synchronising the availability of N and energy on rumen function and production responses of dairy cows – a review. Animal Research 55, 1–24.CrossRefGoogle Scholar
Chouinard, P. Y., Levesque, J., Girard, V. & Brisson, G. J. (1997). Dietary soybeans extruded at different temperatures: Milk composition and in situ fatty acid reactions. Journal of Dairy Science 80, 2913–2924.CrossRefGoogle ScholarPubMed
Clark, R. M., Chandler, P. T. & Park, C. S. (1978). Limiting amino acids for milk protein synthesis by bovine mammary cells in culture. Journal of Dairy Science 61, 408–413.CrossRefGoogle ScholarPubMed
Clark, J. H., Klusmeyer, T. H. & Cameron, M. R. (1992). Microbial protein synthesis and flows of nitrogen fractions to the duodenum of dairy cows. Journal of Dairy Science 75, 2304–2323.CrossRefGoogle Scholar
CVB (1991). Protein Evaluation for Ruminants: The DVE System. In Dutch [Eiwitwaardering voor herkauwers: Het DVE systeem]. CVB reeks nr. 7. The Netherlands: Centraal Veevoeder Bureau, Lelystad.Google Scholar
CVB (2003 a). Manual for Feed Evaluation of Forages. In Dutch [Handleiding Voederwaardeberekening Ruwvoeders]. Lelystad, The Netherlands: Centraal Veevoeder Bureau.Google Scholar
CVB (2003 b). Protocol for in situ Rumen Incubations: Determination of Degradation Rate and Washable Fractions of Protein, Starch, Cell Walls and Organic Residual Fraction. In Dutch [Protocol voor in situ pensincubatie: bepaling van afbraaksnelheid en uitwasbare fracties van eiwit, zetmeel, celwanden en organische restfractie]. Lelystad: Centraal Veevoeder Bureau.Google Scholar
CVB (2005). Feeding Tables. In Dutch [Tabellenboek Veevoeding: voedernormen landbouwhuisdieren en voederwaarde veevoeders]. Lelystad, The Netherlands: Centraal Veevoeder Bureau.Google Scholar
CVB (2007). CVB Tables Ruminants 2007. Lelystad, The Netherlands: Centraal Veevoeder Bureau.Google Scholar
Dijkstra, J., France, J. & Davies, D. R. (1998 a). Different mathematical approaches to estimating microbial protein supply in ruminants. Journal of Dairy Science 81, 3370–3384.CrossRefGoogle ScholarPubMed
Dijkstra, J., France, J. & Tamminga, S. (1998 b). Quantification of the recycling of microbial nitrogen in the rumen using a mechanistic model of rumen fermentation processes. Journal of Agricultural Science, Cambridge 130, 81–94.CrossRefGoogle Scholar
Dijkstra, J., Mills, J. A. N. & France, J. (2002). The role of dynamic modelling in understanding the microbial contribution to rumen function. Nutrition Research Reviews 15, 67–90.CrossRefGoogle ScholarPubMed
Dijkstra, J., Pellikaan, W. F. & Tamminga, S. (2005). Rumen Passage rates of Different Carbohydrate Fractions in Various Feedstuffs. In Dutch [Pens-passagesnelheden van koolhydraatfacties van verschillende typen voedermiddelen]. Report WVH 05-91, Animal Nutrition Group, Wageningen University, Wageningen, the Netherlands.Google Scholar
Dijkstra, J., Kebreab, E., Mills, J. A. N., Pellikaan, W. F., López, S., Bannink, A. & France, J. (2007). Predicting the profile of nutrients available for absorption: from nutrient requirement to animal response and environmental impact. Animal 1, 99–111.CrossRefGoogle ScholarPubMed
Enjalbert, F., Eynard, P., Nicot, M. C., Troegeler-Meynadier, A., Bayourthe, C. & Moncoulon, R. (2003). In vitro versus in situ ruminal biohydrogenation of unsaturated fatty acids from a raw or extruded mixture of ground canola seed/canola meal. Journal of Dairy Science 86, 351–359.CrossRefGoogle ScholarPubMed
Fox, D. G., Tedechi, L. O., Tylutki, T. P., Russell, J. B., Van Amburgh, M. E., Chase, L. E., Pell, A. N. & Overton, T. R. (2004). The Cornell Net Carbohydrate and Protein System model for evaluating herd nutrition and nutrient excretion. Animal Feed Science and Technology 112, 29–78.CrossRefGoogle Scholar
Frank, B. & Swensson, C. (2002). Relationship between content of crude protein in rations for dairy cows and milk yield, concentration of urea in milk and ammonia emissions. Journal of Dairy Science 85, 1829–1838.CrossRefGoogle ScholarPubMed
Gibb, M. J., Ivings, W. E., Dhanoa, M. S. & Sutton, J. D. (1992). Changes in body components of autumn-calving Holstein–Friesian cows over the first 29 weeks of lactation. Animal Production 55, 339–360.Google Scholar
Hall, M. B. & Herejk, C. (2001). Differences in yields of microbial crude protein from in vitro fermentation of carbohydrates. Journal of Dairy Science 84, 2486–2493.CrossRefGoogle ScholarPubMed
Hof, G., Tamminga, S. & Lenaers, P. J. (1994). Efficiency of protein utilization in dairy cows. Livestock Production Science 38, 169–178.CrossRefGoogle Scholar
Huhtanen, P. (2005). Critical aspects of feed protein evaluation systems for ruminants. Journal of Animal and Feed Sciences 14 (Suppl 1), 145–170.CrossRefGoogle Scholar
Huhtanen, P. & Hristov, A. N. (2009). A meta-analysis of the effects of dietary protein concentration and degradability on milk protein yield and milk N efficiency in dairy cows. Journal of Dairy Science 92, 3222–3232.CrossRefGoogle Scholar
Huhtanen, P., Vanhatalo, A. & Varvikko, T. (2002). Effects of abomasal infusions of histidine, glucose, and leucine on milk production and plasma metabolites of dairy cows fed grass silage diets. Journal of Dairy Science 85, 204–216.CrossRefGoogle ScholarPubMed
Kebreab, E., France, J., Mills, J. A., Allison, R. & Dijkstra, J. (2002). A dynamic model of N metabolism in the lactating dairy cow and an assessment of impact of N excretion on the environment. Journal of Animal Science 80, 248–259.CrossRefGoogle Scholar
Kennedy, P. M. (2005). Particle dynamics. In Quantitative Aspects of Ruminant Digestion and Metabolism (Eds Dijkstra, J., Forbes, J. M. & France, J.), 2nd edn. pp. 123–156. Wallingford, UK: CAB International.CrossRefGoogle Scholar
Lanzas, C., Broderick, G. A. & Fox, D. G. (2008). Improved feed protein fractionation schemes for formulating rations with the Cornell Net Carbohydrate and Protein System. Journal of Dairy Science 91, 4881–4891.CrossRefGoogle ScholarPubMed
Law, R. A., Young, F. J., Patterson, D. C., Kilpatrick, D. J., Wylie, A. R. G. & Mayne, C. S. (2009). Effect of dietary protein content on animal production and blood metabolites of dairy cows during lactation. Journal of Dairy Science 92, 1001–1012.CrossRefGoogle ScholarPubMed
Madsen, J., Hvelplund, T., Weisbjerg, M. R., Bertilsson, J., Olsson, I., Spörndly, R., Harstad, O. M., Volden, H., Tuori, M., Varvikko, T., Huhtanen, P. & Olafsson, B. L. (1995). The AAT/PBV protein evaluation system for ruminants: a revision. Norwegian Journal of Agricultural Science 19 (Suppl.), 1–37.Google Scholar
Nousiainen, J., Shingfield, K. J. & Huhtanen, P. (2004). Evaluation of milk urea nitrogen as a diagnostic of protein feeding. Journal of Dairy Science 87, 386–398.CrossRefGoogle ScholarPubMed
NRC (2001). Nutrient Requirements of Dairy Cattle. National Research Council. Washington: National Academy Press.Google Scholar
Oba, M. & Allen, M. S. (2003). Effect of diet fermentability on efficiency of microbial nitrogen production in lactating dairy cows. Journal of Dairy Science 86, 195–207.CrossRefGoogle ScholarPubMed
Offer, N. W., Agnew, R. E., Cottrill, B. R., Givens, D. I., Keady, T. W. J., Mayne, C. S., Rymer, C., Yan, T., France, J., Beever, D. E. & Thomas, C. (2002). Feed into milk: an applied feeding model coupled with a new system of feed characterisation. In Recent Advances in Animal Nutrition (Eds Garnsworthy, P. C. & Wiseman, J.), pp. 167–194. Nottingham, UK: Nottingham University Press.Google Scholar
Offner, A. & Sauvant, D. (2004). Prediction of in vivo starch digestion in cattle from in situ data. Animal Feed Science and Technology 111, 41–56.CrossRefGoogle Scholar
Ørskov, E. R. & McDonald, I. (1979). The estimation of protein degradability in the rumen from incubation measurements weighted according to ate of passage. Journal of Agricultural Science, Cambridge 92, 499–503.CrossRefGoogle Scholar
PDV (2006). Analytical Procedures Animal Feed III. Analysis of sugar. In Dutch [Bundel onderzoekmethoden diervoeder deel III. Bepaling van suiker]. The Hague, the Netherlands: Productschap Diervoeder. Available online at: http://www.pdv.nl/lmbinaries/wm-07_suikers.pdf (verified 23 July 2010).Google Scholar
Pellikaan, W. F. (2004). Passage of 13C labelled feed components through the digestive tract of dairy cows. Ph.D. Thesis Wageningen University, 188 p.Google Scholar
Pirt, S. J. (1965). The maintenance energy of bacteria in growing cultures. Proceedings of the Royal Society (Series B) 163, 224–231.Google ScholarPubMed
Porter, M. G. & Murray, R. S. (2001). The volatility of components of grass silage on oven drying and the inter-relationship between dry-matter content estimated by different analytical method. Grass and Forage Science 56, 405–411.CrossRefGoogle Scholar
Rinne, M., Nousiainen, J. & Huhtanen, P. (2009). Effects of silage protein degradability and fermentation acids on metabolizable protein concentration: a meta-analysis of dairy cow production experiments. Journal of Dairy Science 92, 1633–1642.CrossRefGoogle ScholarPubMed
Rulquin, H., Guinard, J. & Vérité, R. (1998). Variation in amino acid content in the small intestine digesta of cattle: development of a prediction model. Livestock Production Science 53, 1–13.CrossRefGoogle Scholar
Rulquin, H., Pisulewski, P. M., Vérité, R. & Guinard, J. (1993). Milk production and composition as a function of postruminal lysine and methionine supply: a nutrient-response approach. Livestock Production Science 37, 69–90.CrossRefGoogle Scholar
Rulquin, H., Vérité, R. & Guinard-Flament, J. (2001). Amino acids truly digestible in the small intestine: the AADI system for the dairy cow. INRA Productions Animales 14, 265–274.CrossRefGoogle Scholar
Russell, J. B. & Baldwin, R. L. (1979). Comparison of maintenance energy expenditures and growth yields among several rumen bacteria grown on continuous culture. Applied Environmental Microbiology 37, 537–543.CrossRefGoogle ScholarPubMed
Russell, J. B., O'Connor, J. D., Fox, D. G., Van Soest, P. J. & Sniffen, C. J. (1992). A net carbohydrate and protein system for evaluating cattle diets: I. Ruminal fermentation. Journal of Animal Science 70, 3551–3561.CrossRefGoogle Scholar
Russell, J. B. & Strobel, H. J. (2005). Microbial energetics. In Quantitative Aspects of Ruminant Digestion and Metabolism (Eds Dijkstra, J., Forbes, J. M. & France, J.), 2nd edn. pp. 229–260. Wallingford, UK: CAB International.CrossRefGoogle Scholar
Schwab, C. G., Satter, L. D. & Clay, A. B. (1976). Response of lactating dairy cows to abomasal infusion of amino acids. Journal of Dairy Science 59, 1254–1270.CrossRefGoogle ScholarPubMed
Seo, S., Tedeschi, L. O., Lanzas, C., Schwab, C. G. & Fox, D. G. (2006). Development and evaluation of empirical equations to predict feed passage rate in cattle. Animal Feed Science and Technology 128, 67–83.CrossRefGoogle Scholar
Shabi, Z., Tagari, H., Murphy, M. R., Bruckental, I., Mabjeesh, S. J., Zamwel, S., Celik, K. & Arieli, A. (2000). Partitioning of amino acids flowing to the abomasum into feed, bacterial, protozoal, and endogenous fractions. Journal of Dairy Science 83, 2326–2334.CrossRefGoogle Scholar
Sniffen, C. J., O'Connor, J. D., Van Soest, P. J., Fox, D. G. & Russell, J. B. (1992). A net carbohydrate and protein system for evaluating cattle diets. II. Carbohydrate and protein availability. Journal of Animal Science 70, 3562–3577.CrossRefGoogle ScholarPubMed
Subnel, A. P. J., Meijer, R. G. M., Van Straalen, W. M. & Tamminga, S. (1994). Efficiency of milk protein production in the DVE protein evaluation system. Livestock Production Science 40, 215–224.CrossRefGoogle Scholar
Tamminga, S. (1993). Influence of feeding management on ruminant fiber digestibility. In Forage Cell Wall Structure and Digestibility (Eds Jung, H.-J. G., Buxton, R. D., Hatfield, R. D. & Ralph, J.), pp. 571–602. Madison, WI: American Society of Agronomy.Google Scholar
Tamminga, S., Brandsma, G. G., Dijkstra, J., Van Duinkerken, G., Van Vuuren, A. M. & Blok, M. C. (2007). Protein Evaluation for Ruminants: The DVE/OEB 2007 System. CVB Documentation report nr. 53. Lelystad, The Netherlands: Centraal Veevoederbureau.Google Scholar
Tamminga, S., Luteijn, P. A. & Meijer, R. G. M. (1997). Changes in composition and energy content of live weight loss in dairy cows with time after parturition. Livestock Production Science 52, 31–38.CrossRefGoogle Scholar
Tamminga, S., van Straalen, W. M., Subnel, A. P. J., Meijer, R. G. M., Steg, A., Wever, C. J. G. & Blok, M. C. (1994). The Dutch protein evaluation system: The DVE\OEB system. Livestock Production Science 40, 139–155.CrossRefGoogle Scholar
Thomas, C. (Ed) (2004). Feed into Milk: A New Applied Feeding System for Dairy Cows. Nottingham, UK: Nottingham University Press.Google Scholar
Tuori, M., Kaustell, K. V. & Huhtanen, P. (1998). Comparison of the protein evaluation systems of feeds for dairy cows. Livestock Production Science 55, 33–46.CrossRefGoogle Scholar
Ulyatt, M. J., Dellow, D. W., Reid, C. S. W. & Bauchop, T. (1975). Structure and function of the large intestine in ruminants. In Digestion and Metabolism in the Ruminant (Eds McDonald, I. W. & Warner, A. C. I.), pp. 119–133. Armidale, Australia: University of New England Publishing Unit.Google Scholar
Valk, H. (2002). Nitrogen and phosphorus supply of dairy cows. Ph.D. Thesis, Utrecht University.Google Scholar
Van Bruchem, J., Bongers, L. J. G. M., Van Walsem, J. D., Onck, W. & Van Adrichem, P. W. M. (1985). Digestion of proteins of varying degradability in sheep. 3. Apparent and true digestibility in the small intestine; ileal endogenous flow of N and amino acids. Netherlands Journal of Agricultural Science 33, 285–295.CrossRefGoogle Scholar
Van Den Top, A. M., Schonewille, J. Th. & Beynen, A. C. (2000). Feeding Pregnant Cows in the Dry Period. [In Dutch: Voeding van drachtige koeien in de droogstand]. CVB Documentation Report nr 27, 48 pp. Lelystad, The Netherlands: Centraal Veevoederbureau.Google Scholar
Van Der Honing, Y., Gerlofsma, M. H. & Van Vuuren, A. M. (2004). Passage of the Washable Protein Fractions in the Rumen. In Dutch [Passage van de uitwasbare eiwitfracties in de pens]. Report 03/0005924, Animal Sciences Group of Wageningen UR, Lelystad, The Netherlands.Google Scholar
Van Duinkerken, G., André, G., Smits, M. C. J., Monteny, G. J. & Sebek, L. B. J. (2005). Effect of rumen-degradable protein balance and forage type on bulk milk urea concentration and emission of ammonia from dairy cow houses. Journal of Dairy Science 88, 1099–1112.CrossRefGoogle ScholarPubMed
Van Duinkerken, G. & Blok, M. C. (1998). Calculation of the Contents of Intestinal Digestion of Methionine and Lysine in Feeds for Ruminants. In Dutch [Berekening van het gehalte aan darmverteerbaar methionine en lysine in voedermiddelen voor herkauwers]. CVB Documentation Report nr. 22. Lelystad, The Netherlands: Centraal Veevoederbureau.Google Scholar
Van Es, A. J. H. (1978). Feed evaluation for ruminants. The system in use from May 1977 onwards in The Netherlands. Livestock Production Science 5, 331–335.CrossRefGoogle Scholar
Van Knegsel, A. T. M., Van Den Brand, H., Dijkstra, J., Van Straalen, W. M., Heetkamp, M. J. W., Tamminga, S. & Kemp, B. (2007). Dietary energy source in dairy cows in early lactation: energy partitioning and milk composition. Journal of Dairy Science 90, 1467–1476.CrossRefGoogle ScholarPubMed
Van Straalen, W. M. (1995). Modelling of nitrogen flow and excretion in dairy cows. Ph.D. Thesis, Wageningen Agricultural University.Google Scholar
Van Straalen, W. M., Salaun, C., Veen, W. A. G., Rijpkema, Y. S., Hof, G. & Boxem, T. (1994). Validation of protein evaluation systems by means of milk production experiments with dairy cows. Netherlands Journal of Agricultural Science 42, 89–104.CrossRefGoogle Scholar
Van Vuuren, A. M. (1993). Digestion and nitrogen metabolism of grass fed dairy cows. Ph.D. Thesis, Wageningen Agricultural University.Google Scholar
Van Vuuren, A. M. & Tamminga, S. (2001). The physiological base for a minimum rumen protein balance in dairy diets. In Dutch [De fysiologische basis voor de minimale onbestendige eiwit balans in melkveerantsoenen]. CVB Documentation Report nr. 28, 22 pp. Lelystad, The Netherlands: Centraal Veevoederbureau.Google Scholar
Vérité, R., Michalet-Doreau, B., Chapoutot, P., Peyraud, J.-L. & Poncet, C. (1987). Revision of the ileal digestible protein system. [In French: Révision de système des protéines digestibles dans l'intestin (P.D.I.)]. INRA Bulletin Technique CRZV Theix 70, 19–34.Google Scholar
Vérité, R. & Peyraud, J.-L. (1989). Protein: the PDI systems. In Ruminant Nutrition: Recommended Allowances and Feed Tables (Ed. Jarrige, R.), pp. 33–48. London–Paris: INRA/John Libbey Eurotext.Google Scholar
Volden, H., Mydland, L. T. & Olaisen, V. (2002). Apparent ruminal degradation and rumen escape of soluble nitrogen fractions in grass and grass silage administered intraruminally to lactating dairy cows. Journal of Animal Science 80, 2704–2716.Google ScholarPubMed
Zom, R. L. G., Van Riel, J. W., André, G. & Van Duinkerken, G. (2002). Prediction of Feed Intake using the 2002 Dairy Cow Model. In Dutch [Voorspelling voeropname met Koemodel 2002]. Praktijkrapport Rundvee 11. Lelystad, The Netherlands: Praktijkonderzoek Veehouderij.Google Scholar