Effect of Physical State of Coastal Bermuda Grass Hay on Passage through Digestive Tract of Dairy Heifers

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Abstract
The passage of Coastal Bermuda grass hay fed in baled, ground, or pelleted form was traced with brilliant-green-dyed hay through the digestive tract of dairy heifers. The amounts of dry matter found in the entire digestive tract represented 194.2, 175.7, and 110.9% of the previous 24 hr intake of baled, ground, and pelleted hays, respectively. Reticulo-ruminal dry matter recovery represents 75.5, 69.3, and 57.5% of the total found in the entire digestive tract. The more rapid disappearance of pelleted hay from the reticulo-rumen failed to influence the quantity or the length of retention of the digesta posterior to the reticulo-rumen. Recovery of dyed hay followed the same trend, with 91.4, 84.6, and 67.9% of that recovered being found in the reticulo-rumen for baled, ground, and pelleted hay, respectively. Initial appearance of dyed hay in the feces occurred in the 17 to 20 hr collection period with baled hay, in the 13 to 16 hr collection period with ground hay, and in the 0 to 12 hr collection period with pelleted hay. These data indicate the more rapid passage of both ground and pelleted forage through the digestive tract and would appear to explain the decrease in digestibility of these two forms of hay found at this station.