Associative effects between feeds when concentrate supplements are fed to grazing dairy cows: a review of likely impacts on metabolisable energy supply
P. T. Doyle A C , S. A. Francis A B and C. R. Stockdale AA Primary Industries Research Victoria (PIRVic), Department of Primary Industries, Kyabram Centre, 120 Cooma Rd, Kyabram, Vic. 3620, Australia.
B Present address: Plunkett Orchards, 255 McIsaac Rd, Ardmona, Vic. 3629, Australia.
C Corresponding author. Email: peter.doyle@dpi.vic.gov.au
Australian Journal of Agricultural Research 56(12) 1315-1329 https://doi.org/10.1071/AR05087
Submitted: 15 March 2005 Accepted: 18 August 2005 Published: 15 December 2005
Abstract
Efficient conversion of grazed pasture and supplementary feeds into milk is essential to the profitability of dairy farming in southern Australia as costs of production continue to rise. The application of diet formulation approaches to the nutritional management of grazing dairy cows provides unique challenges in predicting the interactions that occur between grazed herbage and supplementary feeds. How feed intake and associative effects between feeds in lactating dairy cows grazing pasture might affect estimated metabolisable energy supplied by the diet are examined.
The effects of increasing feed intake in high-producing dairy cows on decreasing the digestibility of energy, and the compensatory effects of reduced methane production, are reviewed. The factors affecting intake of grazing cows and possible effects on digestibility are considered, and include characteristics of the pasture/forage and amounts and forms of concentrates. Estimates of the potential magnitude of negative associative effects in dairy cows have been made using 2 datasets from recent experiments. Finally, the potential importance of understanding and predicting the magnitude of associative effects for efficient pasture-based dairy production is discussed.
It is concluded that although associative effects between feeds in grazing dairy cows cannot be predicted with certainty, and although they involve complex interactions among a number of variables, ignoring their occurrence can lead to significant errors in both feed evaluation and ration formulation.
Additional keywords: intake, high energy concentrate supplements.
Acknowledgments
The activities undertaken in compiling information and completing this review have received financial support from the Department of Primary Industries, Victoria, the Australian Centre for International Agricultural Research, and the Geoffery Gardiner Dairy Foundation.
ABARE (2002).
Abdalla AL,
Sutton JD,
Humphries DJ, Phipps RH
(1996) Digestibility of diets of grass silage and whole-crop wheat in the rumen of lactating
cows. Animal Science Abstract 62(
), 631.
ADC (2002).
AFRC (1993).
Akin DE
(1979) Microscopic evaluation of forage digestion by rumen microorganisms. A
review. Journal of Animal Science 48, 701–710.
| PubMed |
Armstrong DP,
Knee JE,
Doyle PT,
Pritchard KE, Gyles OA
(2000) Water-use efficiency on irrigated dairy farms in northern Victoria and southern New
South Wales. Australian Journal of Experimental Agriculture 40, 643–653.
| Crossref | GoogleScholarGoogle Scholar |
Bailey RW
(1973) Structural carbohydrates. ‘Chemistry and biochemistry of herbage’. Vol. 1,(Eds GW Butler, RW Bailey)
pp. 157–211. (Academic Press: New York)
Bargo F,
Muller LD,
Delahoy JE, Cassidy TW
(2002) Performance of high producing dairy cows with three different feeding systems
combining pasture and total mixed rations. Journal of Dairy Science 85, 2948–2963.
| PubMed |
Bargo F,
Muller LD,
Kolver ES, Delahoy JE
(2003) Invited review: Production and digestion of supplemented dairy cows on
pasture. Journal of Dairy Science 86, 1–42.
| PubMed |
Beever, DE ,
Cammell, SB ,
Sutton, JD ,
Spooner, MC ,
Haines, MJ ,
and
Harland, JI (1989).
Beever DE,
Cammell SB,
Thomas C,
Spooner MC,
Haines MJ, Gale DL
(1988) The effect of date of cut and barley substitution on gain and on the efficiency of
utilisation of grass silage by growing cattle 2. Nutrient supply and energy partition. British Journal of Nutrition 60, 307–319.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Beever DE, Siddons RC
(1984) Digestion and metabolism in the grazing ruminant. ‘Control of digestion and metabolism in ruminants’. (Eds LP Milligan, WL Grovum, A Dobson)
pp. 479–497. (Prentice-Hall: Englewood Cliffs, NJ)
Boadi DA,
Wittenberg KM, McCaughey WP
(2002) Effects of grain supplementation on methane production of grazing steers using the
sulphur (SF6) tracer gas technique. Canadian Journal of Animal Science 82, 151–157.
Brown LD
(1966) Influence of intake on feed utilization. Journal of Dairy Science 49, 223–230.
Cammell SB,
Sutton JD,
Humphries DJ,
Phipps RH, Beever DE
(1996) Energy balance of lactating cows given diets of grass silage and whole-crop
wheat. Animal Science Abstract 62, 632.
Cohen DC, Doyle PT
(2000) A pasture database for Victorian dairy producers. Asian-Australasian Journal of Animal Sciences 13 Suppl. Vol. A
, 61.
Cohen DC,
Doyle PT,
Stockdale CR, Wales WJ
(2000) Pasture allowance x pasture intake relationships: Victorian and overseas
data. Asian-Australasian Journal of Animal Sciences 13 Suppl. Vol. B
, 119.
Colucci PE,
Chase LE, Van Soest PJ
(1982) Level of feed intake and diet digestibility in dairy cattle. Journal of Dairy Science 65, 1445–1456.
Colucci PE,
Macleod GK,
Grovum WL,
Cahill LW, McMillan I
(1989) Comparative digestion in sheep and cattle fed different forage to concentrate ratios at
high and low intakes. Journal of Dairy Science 72, 1774–1785.
| PubMed |
DeGregario RM,
Tucker RE,
Mitchell GE, Gill WW
(1982) Carbohydrate fermentation in the lower intestine of lambs. Journal of Animal Science 54, 855–862.
| PubMed |
Dixon RM
(1986) Effects of dietary concentrates on rumen digestion of fibrous feedstuffs. Animal Feed Science and Technology 14, 193–202.
| Crossref | GoogleScholarGoogle Scholar |
Dixon RM, Stockdale CR
(1999) Associative effects between forages and grains: consequences for feed
utilisation. Australian Journal of Agricultural Research 50, 757–773.
| Crossref | GoogleScholarGoogle Scholar |
Doyle PT,
Armstrong DP,
Knee JE,
Pritchard KE, Gyles OA
(2000b) Feeding systems and water use efficiency on irrigated dairy farms in northern
Victoria and southern New South Wales. Asian-Australasian Journal of Animal Sciences 13 Suppl. Vol. A, 37–39.
Doyle PT,
Ho C,
Armstrong DP, Malcolm LR
(2004) Modelling feeding efficiency and profitability of an irrigated dairy farm. Animal Production in Australia 25, 45–48.
Doyle P, Malcolm B, Ho C, Nesseler R
(2002) Future dairy farming systems in irrigation regions. DAV 10769 Final Report, Department of Natural Resources and Environment, Kyabram, Vic.
Doyle, PT ,
Stockdale, CR ,
Lawson, AR ,
and
Cohen, DC (2000a).
El-Shazly K,
Dehority BA, Johnson RR
(1961) Effect of starch on the digestion of cellulose in vitro
and in vivo by rumen microorganisms. Journal of Animal Science 20, 268–273.
Ferris CP,
Patterson DC,
Gordon FJ, Kilpatrick DJ
(2000) The effects of incorporating small quantities of straw in grass/grass silage-based diets
for dairy cows. Grass and Forage Science 55, 146–158.
| Crossref | GoogleScholarGoogle Scholar |
Finger T,
Steingass H, Drochner W
(1998) Einfluß von teilgeschützten Fetten in der Ration und
Fütterungsniveau auf die Methanbildung bei Milchkühen. Proceedings of the Society of Nutrition Physiology Abstract 7, 48.
Francis SA,
Chapman DF,
Doyle PT,
Leury BJ, Egan AR
(2002) Non-structural carbohydrate content of a perennial ryegrass cultivar bred for high
sugar levels, compared to ‘normal’ perennial ryegrass and white clover. Animal Production in Australia 24, 73–76.
Freer M,
Moore AD, Donnelly JR
(1997) GRAZPLAN: decision support systems for Australian grazing enterprises—II.
The animal biology model for feed intake, production and reproduction and the GrazFeed
DSS. Agricultural Systems 54, 77–126.
| Crossref | GoogleScholarGoogle Scholar |
Fulkerson, B ,
and
Doyle, P (2001).
Gabel M,
Pieper B,
Friedel K,
Radke M,
Haemann A,
Voigt J, Kuhla S
(2003) Influence of nutrition level on digestibility in high yielding cows and effects on
energy evaluation systems. Journal of Dairy Science 86, 3992–3998.
| PubMed |
Garcez-Yepez P,
Kunkle WE,
Bates DB, Moore JE
(1997) Effects of supplemental energy source and amount on forage intake and performance
by steers and intake and digestibility by sheep. Journal of Animal Science 75, 1918–1925.
| PubMed |
Grant RJ, Mertens DR
(1992) Influence of buffer pH and raw corn starch addition on in vitro fiber
digestion kinetics. Journal of Dairy Science 75, 2762–2768.
| PubMed |
Granzin BC
(2004) Effects of supplement grain type and level of feeding on the milk production of early-
lactation Holstein-Friesian cows grazing temperate and tropical pastures. Australian Journal of Experimental Agriculture 44, 735–743.
| Crossref | GoogleScholarGoogle Scholar |
Hameleers A
(1998) The effects of the inclusion of either maize silage, fermented whole crop wheat or
urea-treated whole crop wheat in a diet based on a high-quality grass silage on the performance of
dairy cows. Grass and Forage Science 53, 157–163.
| Crossref | GoogleScholarGoogle Scholar |
Heard JW,
Cohen DC,
Doyle PT,
Wales WJ, Stockdale CR
(2004) Diet Check—a tactical decision support tool for feeding decisions with grazing
dairy cows. Animal Feed Science and Technology 112, 177–194.
| Crossref | GoogleScholarGoogle Scholar |
Heard JW,
Lyttle SM,
Doyle PT, Stockdale CR
(2002) An annual pasture database for irrigated dairy farms in southern Australia. Animal Production in Australia 24, 307.
Hill J, Leaver JD
(1991) Replacement of whole crop wheat by grass silage in the diet of dairy cows. Animal Production Abstract 52, 606.
Holmes CW
(1987) Pastures for dairy cows. ‘Livestock feeding on pasture’. Occasional Publication No. 10. pp. 133–143. (New Zealand Society of Animal Production: Christchurch, NZ)
Huhtanen P
(1991) Associative effects of feeds in ruminants. Norwegian Journal of Agricultural Sciences Suppl. 5, 37–57.
Hulme DJ,
Kellaway RC,
Booth PJ, Bennett L
(1986) The CAMDAIRY model for formulating and analysing dairy cow rations. Agricultural Systems 22, 81–108.
| Crossref | GoogleScholarGoogle Scholar |
Johnson KA, Johnson DE
(1995) Methane emissions from cattle. Journal of Animal Science 73, 2483–2492.
| PubMed |
Kellaway, R ,
and
Harrington, T (2004).
Knowlton KF
(2001) High grain diets for dairy cattle. ‘Recent Advances in Animal Nutrition in Australia 2001’. Vol. 13,(Ed. JL Corbett)
pp. 19–28. (University of New England: Armidale, NSW)
Kolver ES, Muller LD
(1998) Performance and nutrient intake of high producing Holstein cows consuming pasture
or a total mixed ration. Journal of Dairy Science 81, 1403–1411.
| PubMed |
Lemerle C
(1991) Roughage utilization by sheep in different physiological states. PhD thesis, The University of Melbourne, Australia.
Leventini MW,
Hunt CW,
Roffler RE, Casebolt DG
(1990) Effect of dietary level of barley-based supplements and ruminal buffer on digestion
and growth by beef cattle. Journal of Animal Science 68, 4334–4344.
| PubMed |
Low SG, Kellaway RC
(1983) The utilization of ammonia-treated whole wheat grain by young steers. Animal Production 37, 113–118.
MAFF
(1975) Energy allowances and feeding systems for ruminants. UK Ministry of Agriculture, Fisheries and Food, Technical Bulletin No.33, HMSO, London.
MAFF
(1984) Energy allowances and feeding systems for ruminants. UK Ministry of Agriculture, Fisheries and Food, Technical Bulletin No.433, HMSO, London.
McDonald, P ,
Edwards, RA ,
Greenhalgh, JFD ,
and
Morgan, CA (1995).
Moore JE,
Brant MH,
Kunkle WE, Hopkins DI
(1999) Effects of supplementation on voluntary forage intake, diet digestibility, and animal
performance. Journal of Animal Science 77 (Suppl. 2), 122–135.
| PubMed |
Mould FL
(1988) Associative effects of feeds. ‘Feed science’. World Animal Science; B4. (Ed. ER Ørskov)
pp. 279–292. (Elsevier: Amsterdam)
Mould FL,
Ørskov ER, Gauld SA
(1983a) Associative effects of mixed feeds. II. The effect of dietary addition of bicarbonate
salts on the voluntary intake and digestibility of diets containing various proportions of hay and
barley. Animal Feed Science and Technology 10, 31–47.
| Crossref | GoogleScholarGoogle Scholar |
Mould FL,
Ørskov ER, Mann SO
(1983b) Associative effects of mixed feeds. I. Effects of type and level of supplementation
and the influence of the rumen fluid pH on cellulolysis in vivo and dry matter
digestion of various roughages. Animal Feed Science and Technology 10, 15–30.
| Crossref | GoogleScholarGoogle Scholar |
Mulholland JG,
Coombe JB, McManus WR
(1976) Effect of starch on the utilization by sheep of a straw diet supplemented with urea and
minerals. Australian Journal of Agricultural Research 27, 139–153.
| Crossref | GoogleScholarGoogle Scholar |
Norton BW
(1982) Differences between species in forage quality. ‘Nutritional limits to animal production from pastures’. (Ed. JB Hacker)
pp. 89–110. (Commonwealth Agricultural Bureaux: Farnham Royal, UK)
NRC (2001).
Opatpatanakit Y
(1994) Cereal grains/forage interactions in ruminant diets. PhD thesis, The University of Sydney, New South Wales, Australia.
Opatpatanakit Y,
Kellaway RC,
Lean IJ,
Annison G, Kirby A
(1994) Microbial fermentation of cereal grains in vitro. Australian Journal of Agricultural Research 45, 1247–1263.
| Crossref | GoogleScholarGoogle Scholar |
Opatpatanakit Y,
Kellaway RC,
Lean IJ,
Annison G, Kirby A
(1995) Effects of cereal grains on fibre digestion in vivo. Australian Journal of Agricultural Research 46, 403–413.
| Crossref | GoogleScholarGoogle Scholar |
Ørskov ER
(1979) Recent information on processing grain for ruminants. Livestock Production Science 6, 335–347.
| Crossref | GoogleScholarGoogle Scholar |
Ørskov ER
(1980) Whole grain feeding for ruminants. The Veterinary Record 106, 399–401.
| PubMed |
Ørskov ER, Fraser C
(1975) The effects of processing of barley-based supplements on rumen pH, rate of digestion
and voluntary intake of dried grass in sheep. The British Journal of Nutrition 34, 493–500.
Osbourn DF, Terry RA, Cammell SB, Outen GE
(1970) Some effects of feeding supplements of maize meal and sodium bicarbonate upon the
digestion of forage cellulose by sheep. ‘Proceedings of the Nutrition Society’. Vol. 29. (Ed. JML Stephen ,
EC Owen ,
CC Balch )
pp. 12A–13A. (The Nutrition Society: London)
Palmquist DL, Jenkins TC
(1980) Fat in lactation rations: review. Journal of Dairy Science 63, 1–14.
| PubMed |
Penno JW
(2001) The response by grazing dairy cows to supplementary feeds. PhD thesis, Massey University, Palmerston North, New Zealand.
Phipps RH,
Sutton JD, Jones BA
(1995) Forage mixtures for dairy cows: the effect on dry matter intake and milk production
of incorporating either fermented or urea-treated whole crop wheat, brewers grains, fodder beet or
maize silage into diets based on grass silage. Animal Science 61, 491–496.
Raymond WF
(1969) The nutritive value of forage crops. ‘Advances in agronomy’. Vol. 21, pp. 1–108. (Ed. NC Brady)
(Academic Press: New York)
Robertson LJ, Waghorn GC
(2002) Dairy industry perspectives on methane emissions and production from cattle fed
pasture or total mixed rations in New Zealand. Proceedings of the New Zealand Society of Animal Production 62, 213–218.
Rodriguez VB
(2003) Technology and farm management practices in the Australian dairy industry. ABARE report prepared for Dairy Australia. Australian Bureau of Agriculture and Resource Economics, Canberra, ACT.
Rogers GL, Porter RHD, Robinson I
(1982) Comparison of perennial rye-grass and white clover for milk production. ‘Proceedings of the Conference on Dairy Production from Pasture’. 2–5 February 1982. (New Zealand and Australian Societies of Animal Production: Hamilton, New Zealand)
Russell JB
(1998) The importance of pH in the regulation of ruminal acetate to propionate ratio and
methane production in vitro. Journal of Dairy Science 81, 3222–3230.
| PubMed |
Russell JB, Baldwin RL
(1978) Substrate preferences in rumen bacteria: evidence of catabolite regulatory
mechanisms. Applied and Environmental Microbiology 36, 319–329.
Russell JB, Baldwin RL
(1979) Comparison of substrate affinities among several rumen bacteria: a possible
determinant of rumen bacterial competition. Applied and Environmental Microbiology 37, 531–536.
Russell JB,
Sharp WM, Baldwin RL
(1979) The effect of pH on maximum bacterial growth rate and its possible role as a
determinant of bacterial competition in the rumen. Journal of Animal Science 48, 251–255.
Russell JB, Wilson DB
(1996) Why are ruminal cellulolytic bacteria unable to digest cellulose at low pH? Journal of Dairy Science 78, 1503–1509.
Schiemann R,
Jentsch W,
Hoffmann L, Wittenburg H
(1970) Die Verwertung der Futterenergie für die Milchproduktion. 1. Mitteiling:
Untersuchungen an Tieren mit unterschiedlichem Leistungspotential. Archiv fur Tierernahrung 20, 227–251.
Schiemann R,
Jentsch W, Wittenburg H
(1971) Zur Abhängigkeit der Verdaulichkeit der Energie und der Nährstoffe
von der Höhe der Futteraufnahme und der Rationszusammensetzung bei
Milchkühen. Archiv fur Tierernahrung 21, 223–240.
Sriskandarajah N,
Ashwood A, Kellaway RC
(1980) Effects of rolling and alkali treatment of barley grain supplements on forage intake
and utilization by steers and lactating cows. Journal of Agricultural Science, Cambridge 95, 555–562.
Standing Committee on Agriculture (1990).
Stockdale CR
(1985) Influence of some sward characteristics on the consumption of irrigated pastures
grazed by lactating dairy cattle. Grass and Forage Science 40, 31–39.
Stockdale CR
(1992) Legumes in dairy farming in Victoria. Proceedings of the Australian Society of Animal Production 19, 343–351.
Stockdale CR
(1994a) Persian clover and maize silage. 1. Silage as a supplement for lactating cows offered
herbage of different quality. Australian Journal of Agricultural Research 45, 1751–1765.
| Crossref |
Stockdale CR
(1994b) Persian clover and maize silage. 2. Rumen fermentation and balance of nutrients
when clover and silage are fed to lactating cows. Australian Journal of Agricultural Research 45, 1783–1798.
| Crossref |
Stockdale CR
(1999) The nutritive characteristics of herbage consumed by grazing dairy cows affect milk
yield responses obtained from concentrate supplementation. Australian Journal of Experimental Agriculture 39, 379–387.
| Crossref | GoogleScholarGoogle Scholar |
Stockdale CR
(2000) Levels of pasture substitution when concentrates are fed to grazing dairy cows in
northern Victoria. Australian Journal of Experimental Agriculture 40, 913–921.
| Crossref | GoogleScholarGoogle Scholar |
Stockdale, CR ,
Dellow, DW ,
Grainger, C ,
Dalley, DE ,
and
Moate, PJ (1997).
Sutton JD,
Abdalla AL,
Phipps RH,
Cammell SB, Humphries DJ
(1997) The effect of the replacement of grass silage by increasing proportions of urea-treated
whole crop wheat on food intake and apparent digestibility and milk production by dairy
cows. Animal Science 65, 343–351.
Terry RA,
Tilley JMA, Outen GE
(1969) Effect of pH on cellulose digestion under in vitro
conditions. Journal of the Science of Food and Agriculture 20, 317–320.
| PubMed |
Thomas C,
Gibbs BG,
Beever DE, Thurnham BR
(1988) The effect of date of cut and barley substitution on gain and on the efficiency of
utilisation of grass silage by growing cattle 1. Gains in live weight and its components. The British Journal of Nutrition 60, 297–306.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Tyrrell HF, Moe PW
(1975) Production efficiency in the high producing cow. Effect of intake on digestion
efficiency. Journal of Dairy Science 58, 1151–1163.
Ulyatt MJ, Dellow DW, John A, Reid CSW, Waghorn GC
(1986) Contribution of chewing during eating and rumination to the clearance of digesta
from the reticulorumen. ‘Control of digestion and metabolism in the ruminant’. (Eds LP Milligan, WL Grovum, A Dobson)
pp. 498–515. (Prentice-Hall: Englewood Cliffs, NJ)
Ulyatt MJ, Egan AR
(1979) Quantitative digestion of fresh herbage by sheep. V. The digestion of four herbages
and prediction of sites of digestion. Journal of Agricultural Science, Cambridge 92, 605–616.
Van Soest, PJ (1987).
Van Soest PJ,
Robertson JB, Lewis BA
(1991) Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in
relation to animal nutrition. Journal of Dairy Science 74, 3583–3597.
| PubMed |
de Veth MJ, Kolver ES
(2001) Digestion of ryegrass pasture in response to change in pH in continuous
culture. Journal of Dairy Science 84, 1449–1457.
| PubMed |
Wales WJ
(2005) Factors influencing excretion of milk fat in grazing dairy cows. PhD thesis, The University of Melbourne, Australia.
Wales WJ, Doyle PT
(2003) The effect of grain and straw supplementation on marginal milk production responses
and rumen fermentation of cows grazing highly digestible subterranean clover pasture. Australian Journal of Experimental Agriculture 43, 467–474.
| Crossref | GoogleScholarGoogle Scholar |
Wales WJ,
Doyle PT, Dellow DW
(1998) Dry matter intake and nutrient selection by
lactating cows grazing irrigated pastures at different pasture allowances in summer and
autumn. Australian Journal of Experimental
Agriculture 38, 451–460.
| Crossref | GoogleScholarGoogle Scholar |
Wales WJ,
Doyle PT,
Stockdale CR, Dellow DW
(1999) Effects of variations in herbage mass, allowance and level of supplement on nutrient
intake and milk production of dairy cows in spring and summer. Australian Journal of Experimental Agriculture 39, 119–130.
| Crossref | GoogleScholarGoogle Scholar |
Wales WJ,
Kolver ES,
Thorne PL, Egan AR
(2004) Diurnal variation in ruminal pH on the digestibility of highly digestible perennial
ryegrass during continuous culture fermentation. Journal of Dairy Science 87, 1864–1871.
| PubMed |
Wales WJ, Stockdale CR, Doyle PT
(2005) Plant and sward characteristics to achieve high intake in ruminants. ‘Utilisation of grazed grass in temperate animal systems. Proceedings of a Satellite Workshop of the XX International Grassland Congress’. Cork, Ireland. (Ed. JJ Murphy )
pp. 37–47. (Wageningen Academic Publishers: Wageningen, The Netherlands)
Wales WJ,
Williams YJ, Doyle PT
(2001) Effect of grain supplementation and the provision of chemical and physical fibre on
marginal milk production responses of cows grazing perennial ryegrass pastures. Australian Journal of Experimental Agriculture 41, 465–471.
| Crossref | GoogleScholarGoogle Scholar |
Walker GP,
Stockdale CR,
Wales WJ,
Doyle PT, Dellow DW
(2001) Effect of level of grain supplementation on milk production responses of dairy cows
in mid-late lactation when grazing irrigated pastures high in paspalum (Paspalum
dilatatum Poir). Australian Journal of Experimental Agriculture 41, 1–11.
| Crossref | GoogleScholarGoogle Scholar |
Wedekind KJ,
Muntifering RB, Barker KB
(1986) Effects of diet concentrate level and sodium bicarbonate on site and extent of forage
fiber digestion in the gastrointestinal tract of wethers. Journal of Animal Science 62, 1388–1395.
| PubMed |
Weiss WP
(1999) Energy prediction equations for ruminant feeds. ‘Proceedings of the 61st Cornell Nutrition Conference for Feed
Manufacturers’. Rochester, NY. (New York State College of Agriculture and Life Sciences: Ithaca, NY)
Williams YJ,
Doyle PT,
Egan AR, Stockdale CR
(2005b) Increasing the intake of highly digestible Persian clover herbage reduces rumen fluid
pH and the rate of degradation of neutral detergent fibre in grazing dairy cows. Australian Journal of Experimental Agriculture (in press) 45,
| Crossref |
Williams YJ,
Walker GP,
Doyle PT,
Egan AR, Stockdale CR
(2005a) Rumen fermentation characteristics of dairy cows grazing different allowances of
Persian clover or perennial ryegrass-dominant swards in spring. Australian Journal of Experimental Agriculture 45, 665–675.
| Crossref | GoogleScholarGoogle Scholar |
Williams YJ,
Walker GP,
Wales WJ, Doyle PT
(2001) Effect of pasture type and intake on the rumen pH of grazing dairy cows in
spring. Australian Journal of Dairy Technology 56, 156.
Yan T,
Ferris CP,
Agnew RE, Gordon FJ
(2004) Effects of feeding level on energy concentration in grass silage-based diets offered to
dairy cattle. Journal of Dairy Science 87, 1425–1427.
| PubMed |
