Comparison of methods used to predict the in vivo digestibility of feeds in ruminants

Australian Journal of Agricultural Research

Volumn 50, Issue 5, 1999, Pages 825-841

  Kitessa, S ^a   Flinn, P C ^b   Irish, G G ^b,c  

^a CSIRO   (Australia)

^b Hamilton Research Institute   (Australia)

^c Schweppes Australia Pty Ltd   (Australia)

Author keywords

Chemical composition; Enzymatic methods; In situ; In vitro; NIRS; Pepsin cellulase

Indexed keywords

ANIMALIA; BOVIDAE;

EID: 0033029636     PISSN: 00049409     EISSN: None     Source Type: Journal    
DOI: 10.1071/AR98169     Document Type: Article

References (111)

1. AAC-SCA (1990). Australian Agricultural Council-Standing Committee on Agriculture: Ruminant Subcommittee. Feeding standards for Australian livestock: Ruminants. (CSIRO Publications: East Melbourne.)
2. Abrams, S. M. (1988). Sources of error in predicting digestible dry matter from the acid-detergent fibre content of forages. Animal Feed Science and Technology 21, 205-8.
3. Aerts, J. V., De Brabander, D. L., Cottyn, B. G, and Buysse, F. X. (1977). Comparison of laboratory methods for predicting the organic matter digestibility of forages. Animal Feed Science and Technology 2, 337-49.
4. AFRC (1992). Agricultural Food Research Council. Technical Committee on Response to Nutrients. Report No. 9. Nutrient Requirements of Ruminant Animals: Protein. Nutrition Abstracts and Reviews 62B, 787-835.
5. AFRC (1993). Agricultural Food Research Council. Energy and Protein Requirement of ruminants. An advisory manual prepared by AFRC Technical Committee on Response to Nutrients. (CAB International: Wallingford, UK.)
6. Aiple, K. P., Steingass, H., and Drochner, W. (1996). Prediction of the net energy content of raw materials and compound feeds for ruminants by different laboratory methods. Archives of Animal Nutrition 49, 213-20.
7. Akhter, S., Owen, E., Fall, A., O'Donovan, F., and Theodorou, M. K. (1994). Use of fresh or frozen cow faeces instead of sheep rumen liquor to provide micro-organisms for in vitro digestibility assays for forages. Animal Production 58, 452.
8. Aldrich, C. G., Merchen, N. R., Nelson, D. R., and Barmore, J. A. (1995). The effects of roasting temperature applied to whole soybeans on site of digestion by steers: II. Protein and amino acid digestion. Journal of Animal Science 73, 2131-40.
9. Armstrong, R. H., Common, T. G., and Davies, G J. (1989). The prediction of the diet of sheep and cattle grazing indigenous hill plant communities by in vitro digestion, faecal nitrogen concentration or 'indigestible' acid-detergent fibre. Grass and Forage Science 44, 303-13.
10. Ayres, J. F. (1991). Sources of error with in vitro digestibility assay of pasture feeds. Grass and Forage Science 46, 89-97.
11. Balch, C. C., and Johnson, V. W. (1950). Factors affecting the utilisation of food by dairy cows. Factors influencing the rate of breakdown of cellulose (cotton threads) in the rumen of the cow. British Journal of Nutrition 4, 389-94.
12. Barber, W. P., Adamson, A. H., and Altman, J. F. B. (1984). New methods of forage evaluation. In 'Recent Advances in Animal Nutrition'. (Eds W. Haresign and D. J. A. Cole.) pp. 161-76. (Butterworths: London.)
13. Barber, G. D., Givens, D. I., Kridis, M. S., Offer, N. W., and Murray, I. (1990). Prediction of the organic matter digestibility of grass silage. Animal Feed Science and Technology 28, 115-28.
14. Baumgardt, B. R., and Ho, H. K. (1964). Evaluation of forages in the laboratory. IV. Within and among trial variability of the Wisconsin artificial rumen procedure. Journal of Dairy Science 47, 263-6.
15. Belyea, R. L., Marin, P. J., and Sedgwick, H. T. (1985). Utilisation of chopped and long alfalfa hay by dairy heifers. Journal of Dairy Science 68, 1297-301.
16. Beuvink, J. M. W., Spoelstra, S. F., and Hogendorp, R. J. (1992). An automated method for measuring time-course of gas production of feedstuffs incubated with buffered rumen fluid. Netherlands Journal of Agricultural Science 40, 401-7.
17. Bourquin, L. D., Titgemeyer, E. C., Merchen, N. R., and Fahey Jr, G. C. (1994). Forage level and particle size effects on orchardgrass digestion by steers: I. Site and extent of organic matter, nitrogen, and cell wall digestion. Journal of Animal Science 72, 746-58.
18. Byers, F. M., Johnson, D. E., and Preston, R. L. (1982). Level of intake involvement in associative effects between corn grain, corn silage and forage on energy utilisation by beef cattle. In 'Energy Metabolism of Farm Animals'. Proceedings of the 9th Symposium held at Lillehammer, Norway. European Association for Animal Production. EEAP Publication No. 29. (Eds A. Ekern and F. Sundstl.) pp. 128-32. (The Agricultural University of Norway : Ås, Norway.)
19. Carro, M. D., Lopez, S., Gonzalez, J. S., and Ovejero, F. J. (1994). Comparison of laboratory methods for predicting digestibility of hay in sheep. Small Ruminant Research 14, 9-17.
20. Clancy, M. J., and Wilson, R. K. (1966). Development and application of a new chemical method for predicting the digestibility and intake of herbage samples. In 'Proceedings of the Xth International Grassland Congress'. (Ed. A. G. G Hill.) pp. 445-53. (Finish Grassland Association: Helsinki, Finland.)
21. Clarke, T., Flinn, P. C., and McGowan, A. A. (1982). Low-cost pepsincellulase assays for prediction of digestibility of herbage. Grass and Forage Science 37, 147-50.
22. Coelho, M., Hembry, F. G., Barton, F. E., and Saxton, A. M. (1988). A comparison of microbial, enzymatic, chemical and near infrared reflectance spectroscopy methods in forage evaluation. Animal Feed Science and Technology 20, 219-31.
23. Cone, J. W., van Gelder, A. H., and Driehuis, F. (1997). Description of gas production profiles with a three-phasic model. Animal Feed Science and Technology 66, 31-45.
24. Cone, J. W., Van Gelder, A. H., Visscher, G. W. A., and Oudshoorn, L. (1996). Use of a new automated time related gas production apparatus to study the influence of substrate concentration and source of rumen fluid on fermentation kinetics. Animal Feed Science and Technology 61, 113-28.
25. Conrad, H. R., Weiss, W. P., Odwongo, W. O., and Shockey, W. L. (1984). Estimating net energy lactation from components of cell solubles and cell walls. Journal of Dairy Science 67, 427-36.
26. Cottyn, B. G., Aerts, J. V., and Vanacker, J. M. (1986). Use of new chemical and biochemical determinations in predicting digestibility and energy value. In 'Recent Advances in Feed Evaluation and Rationing Systems for Dairy Cattle in Extensive and Intensive Production Systems'. (Eds C. C. Balch and A. J. H. van Es.) pp. 28-32. (International Dairy Federation: Brussels.)
27. De Boever, J. L., Cottyn, B. G, Andries, J. I., Buysse, F. X., and Vanacker, J. M. (1988). The use of a cellulase technique to predict digestibility, metabolisable and net energy of forages. Animal Feed Science and Technology 19, 247-60.
28. De Boever, J. L., Cottyn, B. G, Buysse, F. X., Wainman, F. W., and Vanacker, J. M. (1986). The use of an enzymatic technique to predict digestibility, metabolisable and net energy of compound feedstuffs for ruminants. Animal Feed Science and Technology 14, 302-14.
29. De Boever, J. L., Cottyn, B. G., De Brabander, D. L., Vanacker, J. M., and Boucque, Ch. V. (1996). Prediction of the feeding value of grass silages by chemical parameters, in vitro digestibility and near infrared reflectance spectroscopy. Animal Feed Science and Technology 60, 103-15.
30. Dewhurst, R. J., Hepper, D., and Webster, A. J. F. (1995). Comparison of in sacco and in vitro techniques for estimating the rate and extent of rumen fermentation of a range of dietary ingredients. Animal Feed Science and Technology 51, 211-29.
31. Dowman, M. G., and Collins, F. C. (1982). The use of enzymes to predict the digestibility of animal feeds. Journal of the Science of Food and Agriculture 33, 689-96.
32. El Shaer, H. M., Omed, H. M., Chamberlain, A. G., and Axford, R. F. E. (1987). The use of faecal organisms from sheep for the in vitro determination of digestibility. Journal of Agricultural Science, Cambridge 109, 257-59.
33. Emanuele, S. M., and Staples, C. R. (1988). Effect of forage particle size on in situ digestion kinetics. Journal of Dairy Science 71, 1947-54.
34. Estevez, A. M., Castillo, E., Figuerola, F., and Yanez, E. (1991). Effect of processing on some chemical and nutritional characteristics of pre-cooked and dehydrated legumes. Plant Foods for Human Nutritional, 193-201.
35. Ferret, A., Gasa, J., Casanas, F., Bosch, L., and Nuez, F. (1997). Prediction of voluntary intake and digestibility of maize silages given to sheep from morphological and chemical composition, in vitro digestibility or rumen degradation characteristics. Animal Science 64, 493-501.
36. Fluharty, F. L., and Loerch, S. C. (1989). Chemical treatment of ground corn to limit ruminai starch digestion. Canadian Journal of Animal Science 69, 173-80.
37. Gasa, J., Castrillo, C., Baucells, M. D., and Gauda, J. A. (1989). Byproducts from the canning industry as feedstuff for ruminants: Digestibility and its prediction from chemical composition and laboratory bioassays. Animal Feed Science and Technology 25, 67-77.
38. Givens, D. I., Adamson, A. H., and Cobby, J. M. (1988). The effect of ammoniation on the nutritive value of wheat, barley and oat straws. II. Digestibility and energy value measurements in vitro and their prediction from laboratory measurements. Animal Feed Science and Technology 19, 173-84.
39. Givens, D. I., Baker, C. W., Moss, A. R., and Adamson, A. H. (1991). A comparison of near-infrared reflectance spectroscopy with three in vitro techniques to predict the digestibility in vivo of untreated and ammonia treated cereal straws. Animal Feed Science and Technology 35, 83-94.
40. Givens, D. I., De Boever, J. L., and Deaville, E. R. (1997). The principles, practices and some future applications of near infrared spectroscopy for predicting the nutritive value of foods for animals and humans. Nutrition Research Reviews 10, 83-114.
41. Givens, D. I., Everington, J. M., and Adamson, A. H. (1989). The digestibility and energy content of grass silage and their prediction from laboratory measurements. Animal Feed Science and Technology 24, 27-43.
42. Goering, H. K., and Van Soest, P. J. (1970). 'Forage Fibre Analysis.' USDA Agricultural Handbook No. 379. (USDA: Washington, DC.)
43. Goncalves, L. M. B. O., and Borba, A. E. S. (1996). Study of gas production capacity of three sources of inocula. Journal of Agricultural Science, Cambridge 127, 511-15.
44. Gulati, S. K., Scott, T. W., and Ashes, J. R. (1997). In vitro assessment of fat supplements for ruminants. Animal Feed Science and Technology 64, 127-32.
45. Huntington, J. A., and Givens, D. I. (1995). The in situ technique for studying rumen degradation of feeds. A review of the procedure. Nutrition Abstracts and Reviews 65B, 63-93.
46. Joanning, S. W., Johnson, D. E., and Barry, B. P. (1981). Nutrient digestibility depressions in corn silage-corn grain mixtures fed to steers. Journal of Animal Science 53, 1095-103.
47. Johnson, R. R. (1963). Symposium on microbial digestion in ruminants. In vitro rumen fermentation techniques. Journal of Animal Science 22, 792-800.
48. Johnson, R. R. (1966). Techniques and procedures for in vitro and in vivo rumen studies. Journal of Animal Science 25, 855-75.
49. Jones, D. I. H., and Hayward, M. V. (1975). The effect of pepsin pretreatment of herbage on the prediction of dry matter digestibility from solubility in fungal cellulase solutions. Journal of the Science of Food and Agriculture 26, 711-18.
50. Jung, H. G., and Varel, V. H. (1988). Influence of forage type on ruminal bacterial populations and subsequent in vitro fibre digestion. Journal of Dairy Science 71, 1526-35.
51. Khazaal, K., Dentinho, M. T., Ribeiro, J. M., and Ørskov, E. R. (1993). A comparison of gas production during incubation with rumen contents in vitro and nylon bag degradability as predictors of the apparent digestibility in vivo and the voluntary intake of hays. Animal Production 57, 105-12.
52. Khazaal, K., Dentinho, M. T., Ribeiro, J. M., and Ørskov, E. R. (1995). Prediction of apparent digestibility and voluntary intake of hays fed to sheep: comparison between using fibre components, in vitro digestibility or characteristics of gas production or nylon bag degradation. Animal Production 61, 527-38.
53. van der Koelen, C. J., Goedhart, P. W., van Vuuren, A. M., and Savoini, G. (1992). Sources of variation of the in situ nylon bag technique. Animal Feed Science and Technology 38, 35-42.
54. Krishnamoorthy, U., Sniffen, C. J., and Van Soest, P. J. 1983. Evaluation of a mathematical model of rumen digestion and an in vitro simulation of rumen proteolysis to estimate the rumen-undegraded nitrogen content of feedstuffs. British Journal of Nutrition 50, 555-68.
55. Lindberg, J. E., and Varvikko, T. (1982). The effect of bag pore size on the ruminal degradation of dry matter, nitrogenous compounds and cell walls in nylon bags. Swedish Journal of Agricultural Research 12, 163-71.
56. Lusk, J. W., Browning, C. B., and Miles, J. T. (1962). Small sample in vivo cellulose digestion procedure for forage evaluation. Journal of Dairy Science 45, 69-73.
57. Marinucci, M. T., Dehority, B. A., and Loerch, S. C. (1992). In vitro and in vivo studies of factors affecting digestion of feeds in synthetic fibre bags. Journal of Animal Science 70, 296-307.
58. McDonald, P., Edwards, R. A., Greenhalgh, J. F. D., and Morgan, C. A. (1995). 'Animal Nutrition.' 5th Edn. (Longman Singapore Publishers (Pte.) Ltd: Singapore.)
59. McLeod, M.N., and Minson, D. J. (1969). Sources of variation in the in vitro digestibility of tropical grasses. Journal of the British Grassland Society 24, 244-9.
60. McLeod, M. N., and Minson, D. J. (1978). The accuracy of the pepsin-cellulase technique for estimating the dry matter digestibility of grasses and legumes. Animal Feed Science and Technology 3, 277-87.
61. McLeod, M. N., and Minson, D. J. (1980). A note on Onozuka 3S cellulase as a replacement for Onozuka SS (P1500) cellulase when estimating forage digestibility in vitro. Animal Feed Science and Technology 5, 347-50.
62. Mehrez, A. Z., and Ørskov, E. R. (1977). A study of the artificial fibre bag technique for determining the digestibility of feeds in the rumen. Journal of Agricultural Science, Cambridge 88, 645-50.
63. Meissner, H. H., Koster, H. H., Nieuwoudt, S. H., and Coertze, R. J. (1991). Effect of energy supplementation on intake and digestion of early and mid-season ryegrass and Panicum/Smuts finger hay, on in sacco disappearance of various forage species. South African Journal of Animal Science 21, 33-42.
64. Melo, I. M. P. (1990). Prediction of digestibility of feedstuffs using cell wall constituents and enzymatic solubilities. World Review of Animal Production 25, 83-8.
65. Menke, K. H., Raab, L., Salewski, A., Steingass, H., Fritz, D., and Scheinder, W. (1979). The estimation of the digestibility and metabolisable energy content of ruminant feedingstuffs from the gas production when they are incubated with rumen liquor in vitro. Journal of Agricultural Science, Cambridge 93, 217-22.
66. Meyer, J. H. F., and Mackie, R. I. (1986). Microbial evaluation of the intraruminal in sacculus digestion technique. Applied and Environmental Microbiology 51, 622-9.
67. Michalet-Doreau, B., and Cerneau, P. (1991). Influence of feedstuff particle size on in situ degradation of nitrogen in the rumen. Animal Feed Science and Technology 35, 69-81.
68. Minson, D. J. (1982). Effect of chemical composition on feed digestibility and metabolisable energy. Nutrition Abstracts and Reviews 52B, 591-615.
69. Moe, P. W., and Tyrrell, H. F. (1977). Effects of feed intake and physical form on energy value of corn in Timothy hay diets for lactating cows. Journal of Dairy Science 60, 752-8.
70. Morrison, I. M. (1972). A semi-micro method for the determination of lignin and its use in predicting the digestibility of forage crops. Journal of the Science of Food and Agriculture 23, 455-63.
71. Morrison, I. M. (1983). The effect of physical and chemical treatments on the degradation of wheat and barley straws by rumen liquorpepsin and pepsin-cellulase systems. Journal of the Science of Food and Agriculture 34, 1323-9.
72. Moss, A. R., and Givens, D. I. (1990). Chemical composition and in vitro digestion to predict digestibility of field-cured and barn-cured grass hays. Animal Feed Science and Technology 31, 125-38.
73. Moss, A. R., Givens, D. I., and Everington, J. M. (1990). The effect of sodium hydroxide treatment on the chemical composition, digestibility and digestible energy content of wheat, barley and oat straws. Animal Feed Science and Technology 29, 73-87.
74. Murray, I. (1986). Near infrared reflectance spectroscopy. In 'Recent Advances in Animal Nutrition'. (Eds W. Haresign and D. J. A. Cole.) pp. 141-56. (Butterworths: London.)
75. Nandra, K. S., Oddy, V. H., Ayres, J. F., Nicholls, P. J., Langevad, B., and Ly, W. (1995). The use of cell wall organic matter components and in vitro degradability characteristics to predict intake and digestibility of white clover. Australian Journal of Agricultural Research 46, 1111-20.
76. Nocek, J. E. (1985). Evaluation of specific variables affecting in situ estimates of ruminal dry matter and protein digestion. Journal of Animal Science 60, 1347-58.
77. Nocek, J. E. (1988). In situ and other methods to estimate ruminal protein and energy digestibility: A review. Journal of Dairy Science 71, 2051-69.
78. Norris, K. H., Barnes, R. F., Moore, J. E., and Shenk, J. S. (1976). Predicting forage quality by near infrared reflectance spectroscopy. Journal of Animal Science 43, 889-97.
79. Nsahlai, I. V., and Umunna, N. N. (1996). Comparison between reconstituted sheep faeces and rumen fluid inocula and between in vitro and in sacco degradability methods as predictors of intake and in vivo digestibility. Journal of Agricultural Science, Cambridge 126, 235-48.
80. Oddy, V. H., Robards, G. E., and Low, S. G. (1983). Prediction of in vivo dry matter digestibility from the fibre and nitrogen content of a feed. In 'Feed Information and Animal Production'. (Eds G. E. Robards and R. G. Packham.) pp. 395-98. (Commonwealth Agricultural Bureaux: Farnham Royal, UK.)
81. Omed, H. M., Axford, R. F. E., Chamberlain, A. G., and Givens, D. I. (1989). A comparison of three laboratory techniques for the estimation of digestibility of feedstuffs for ruminants. Journal of Agricultural Science, Cambridge 113, 35-9.
82. Opatpatanakit, Y., Kellaway, R. C., Lean, I. J., Annison, G, and Kirby, A. (1994). Microbial fermentation of cereal grains in vitro. Australian Journal of Agricultural Research 45, 1247-63.
83. Opatpatanakit, Y., Kellaway, R. C., Lean, I. J., Annison, G., and Kirby, A. (1995). Effects of cereal grains on fibre digestion in vitro. Australian Journal of Agricultural Research 46, 403-13.
84. Ørskov, E. R., and McDonald, I. (1979). The estimation of protein degradability in the rumen from incubation measurements weighted according to rate of passage. Journal of Agricultural Science 92, 499-503.
85. Ørskov, E. R., Ojwang, L, and Reid, G. W. (1988). A study on consistency of differences between cows in rumen outflow rate of fibrous particles and other substrates and consequences for digestibility and intake of roughages. Animal Production 47, 45-51.
86. Owens, F. N., Zinn, R. A., and Kim, Y. K. (1986). Limits to starch digestion in the ruminant small intestine. Journal of Animal Science 63, 1634-48.
87. Pell, A. N., and Schofield, P. (1993). Computerised monitoring of gas production to measure forage digestion in vitro. Journal of Dairy Science 16, 1063-73.
88. Quin, J. I., van der Wath, J. G, and Myburgh, S. (1938). Studies on the alimentary tract of merino sheep in South Africa. 4. Description of experimental technique. Onderstepoort, Journal of Veterinary Science and Animal Industry 11, 341-60.
89. Rangnekar, D. V., Badve, V. C., Kharat, S. T., Sobale, B. N., and Joshi, A. L. (1982). Effect of high-pressure steam treatment on chemical composition and digestibility in vitro of roughages. Animal Feed Science and Technology 7, 61-70.
90. Redshaw, E. S., Mathison, G. W., Milligan, L. P., and Weisenburger, R. D. (1986). Near infrared reflectance speclroscopy for predicting forage composition and voluntary consumption and digestibility in cattle and sheep. Canadian Journal of Animal Science 66, 103-15.
91. Roughan, P. G., and Holland, R. (1977). Predicting in vivo digestibilities of herbages by exhaustive enzymatic hydrolysis of cell walls. Journal of the Science of Food and Agriculture 28, 1057-64.
92. Setälä, J. (1983). The nylon bag technique for determination of ruminal feed protein degradation. Journal of Scientific Agricultural Society of Finland 55, 1-78.
93. Sileshi, Z., Owen, E., Dhanoa, M. S., and Theodorou, M. K. (1996). Prediction of in situ rumen DM disappearance of Ethiopian forages from an in vitro gas production technique using pressure transducer, chemical analyses or in vitro digestibility. Animal Feed Science and Technology 61, 73-87.
94. Smith, K. F., and Flinn, P. C. (1991). Monitoring the performance of a broadbased calibration for measuring the nutritive value of two independent populations of pasture using near infrared reflectance (NIR) spectroscopy. Australian Journal of Experimental Agriculture 31, 205-10.
95. Stewart, C. S. (1979). Problems in the assessment of fibre digestion in the rumen. In 'Straw Decay and its Effects on Disposal and Utilisation'. (Ed. E. Grossbard.) pp. 315-19. (John Wiley & Sons: UK.)
96. Terry, R. A., Mundell, D. C., and Osbourn, D. F. (1978). Comparison of two in vitro procedures using rumen liquor-pepsin or pepsin cellulase for prediction of forage digestibility. Journal of the British Grassland Society 33, 13-18.
97. Theodorou, M. K., Williams, B. A., Dhanoa, M. S., McAllan, A. B., and France, J. (1994). A simple gas production method using a pressure transducer to determine the fermentation kinetics of ruminant feeds. Animal Feed Science and Technology 48, 185-97.
98. Theurer, C. B. (1986). Grain processing effects on starch utilisation by ruminants. Journal of Animal Science 63, 1649-62.
99. Thomas, P. C., Robertson, S., and Chamberlain, D. G. (1988). Predicting the metabolisable energy content of compound feeds for ruminants. In 'Recent Advances in Animal Nutrition'. (Eds W. Haresign and D. J. A. Cole.) pp. 127-46. (Butterworths: London.)
100. Tilley, J. M., and Terry, R. A. (1963). A two-stage technique for the in vitro digestion of forage crops. Journal of the British Grassland Society 18, 104-11.
101. Uden, P., (1988). The effect of grinding and pelleting hay on digestibility, fermentation rate, digesta passage and rumen and faecal particle size in cows. Animal Feed Science and Technology 19, 145-57.
102. Van Soest, P. J. (1963). Use of detergents in the analysis of fibrous feeds. Journal of the Association of Official Agricultural Chemists 46, 829-35.
103. Varel, V. H., and Kreikemeier, K. K. (1995). Technical note: Comparison of in vitro and in situ digestibility methods. Journal of Animal Science 73, 578-82.
104. Wanapat, M., Sundstol, F., and Hall, J. M. R. (1986). A comparison of alkali treatment methods used to improve the nutritive value of straw. II. In sacco and in vitro degradation relative to in vivo digestibility. Animal Feed Science and Technology 14, 215-20.
105. Weakley, D. C., Stern, M. D., and Satter, L.D. (1983). Factors affecting the disappearance of feedstuffs from bags suspended in the rumen. Journal of Animal Science 56, 493-507.
106. Weiss, W. P. (1993). Predicting energy value of feeds. Journal of Dairy Science 76, 1802-11.
107. Weiss, W. P. (1994). Estimation of the digestibility of forages by laboratory methods. In 'Forage Quality, Evaluation and Utilisation'. (Ed. G. C. Fahey Jr.) pp. 644-81. (American Society of Agronomy, Inc., Crop Science Society of America, Inc./Soil Science Society of America, Inc.: Madison, WI.)
108. Weiss, W. P., Conrad, H. R., and Pierre, N. R. St. (1992). Atheorelically-based model for predicting total digestible nutrient values of forages and concentrates. Animal Feed Science and Technology 39, 95-110.
109. Williams, A. G. (1988). Factors affecting the formation of polysaccharide-degrading enzymes by rumen micro-organisms. Animal Feed Science and Technology 21, 191-5.
110. Wrigley, C. W. (1999). Potential methodologies and strategies for the rapid assessment of feed grain quality. Australian Journal of Agricultural Research 50, 789-805.
111. Yates, N. G., and Moir, R. J. (1983). Utilisation of oaten hay by cattle: effect of milling and urea supplementation. Australian Journal of Experimental Agriculture and Animal Husbandry 23, 14-18.