Milk Response to Concentrate Supplementation of High Producing Dairy Cows Grazing at Two Pasture Allowances
Open Access
- 1 July 2002
- journal article
- Published by American Dairy Science Association in Journal of Dairy Science
- Vol. 85 (7), 1777-1792
- https://doi.org/10.3168/jds.s0022-0302(02)74252-5
Abstract
Twenty multiparous Holstein cows (four ruminally cannulated) in five 4 x 4 Latin squares with 21-d periods were used to study the effect of concentrate supplementation when grazed at two pasture allowances. The four dietary treatments resulted from the combination of two pasture allowance targets (low, 25 vs. high, 40 kg of dry matter/cow per day) and two concentrate supplementation levels (zero vs. 1 kg of concentrate/4 kg of milk). Concentrate supplementation decreased pasture dry matter intake 2.0 kg/d at the low pasture allowance (17.5 vs. 15.5 kg/d) and 4.4 kg/d at the high pasture allowance (20.5 vs. 16.1 kg/d). Substitution rate was lower at the low pasture allowance (0.26 kg pasture/kg concentrate) than at the high pasture allowance (0.55 kg of pasture/kg of concentrate). Total dry matter intake of both supplemented treatments averaged 24.4 kg/d. Milk production of both supplemented treatments averaged 29.8 kg/d, but was increased with higher pasture allowance in the unsupplemented treatments (19.1 vs. 22.2 kg/d). Milk response to concentrate supplementation was 1.36 and 0.96 kg of milk/kg of concentrate for the low and high pasture allowances, respectively. Concentrate supplementation reduced milk fat percentage but increased milk protein percentage. Rumen pH and NH3-N concentration were decreased with concentrate supplementation. Substitution rate was likely related to both negative associative effects in the rumen (reductions in rumen pH, rate of pasture digestion, and NDF digestibility) and reductions in grazing time. The latter was more important, quantitatively explaining at least 80% of the reduction in pasture dry matter intake observed.Keywords
This publication has 24 references indexed in Scilit:
- Effect of the level of concentrate supplementation, herbage allowance and milk yield at turn-out on the performance of dairy cows in mid lactation at grazingAnimal Science, 2001
- In Situ Dry Matter and Crude Protein Degradation of Fresh Forages During the Spring GrowthJournal of Dairy Science, 1999
- Dry matter intake, nutrient selection and milk production of dairy cows grazing rainfed perennial pastures at different herbage allowances in springAustralian Journal of Experimental Agriculture, 1999
- Associative effects between forages and grains: consequences for feed utilisationAustralian Journal of Agricultural Research, 1999
- Performance and Nutrient Intake of High Producing Holstein Cows Consuming Pasture or a Total Mixed RationJournal of Dairy Science, 1998
- Milk production and ruminal metabolites from cows offered two pasture diets supplemented with non‐structural carbohydrateNew Zealand Journal of Agricultural Research, 1997
- Intake, Site, and Extent of Nutrient Digestion of Lactating Cows Grazing PastureJournal of Dairy Science, 1996
- Ruminal Digestion and Duodenal Nutrient Flows in Dairy Cows Consuming Grass as Pasture, Hay, or SilageJournal of Dairy Science, 1994
- Positive relation between substitution rate and pasture allowance for cows receiving concentratesAustralian Journal of Experimental Agriculture, 1989
- The effect of concentrate supplementation on high-yielding dairy cows under two systems of grazingThe Journal of Agricultural Science, 1986