Grazing Behavior Affects Daily Ruminal pH and NH3 Oscillations of Dairy Cows on Pasture
Grazing behavior of Holstein cows in late lactation at 2 pasture allowances without or with supplementation was studied in a single reversal design. Twenty multiparous cows (4 ruminally cannulated) grazed a bromegrass/orchardgrass pasture offered at 2 pasture allowances: 1) low, and 2) high, with 25...
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Veröffentlicht in: | Journal of dairy science 2005-01, Vol.88 (1), p.303-309 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Grazing behavior of Holstein cows in late lactation at 2 pasture allowances without or with supplementation was studied in a single reversal design. Twenty multiparous cows (4 ruminally cannulated) grazed a bromegrass/orchardgrass pasture offered at 2 pasture allowances: 1) low, and 2) high, with 25 and 40kg/d of DM per cow, respectively. Half of the cows were supplemented with a mineral/vitamin mixture (1kg/ d of the mix in a corn/molasses carrier) and the other half supplemented with a corn-based concentrate (1kg of concentrate per 4kg of milk). Automatic behavior recorders were used to measure grazing time and number of bites. For the mineral/vitamin mixture-supplemented cows, grazing time and number of bites after the p.m. milking was greater and ruminal pH was numerically lower at the high pasture allowance. For the concentrate-supplemented cows, grazing behavior and ruminal pH did not differ between the 2 pasture allowances. Pattern of grazing time of mineral/vitamin mixture-supplemented and concentrate-supplemented cows influenced daily oscillations of ruminal pH and NH3-N concentration. Pasture allowance affected grazing behavior of mineral/vitamin mixture-supplemented cows; however grazing behavior of concentrate-supplemented cows was not affected by pasture allowance. |
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ISSN: | 0022-0302 1525-3198 |
DOI: | 10.3168/jds.S0022-0302(05)72688-6 |