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Change in Nitrogen Fractions and Ruminal Nitrogen Degradability of Orchardgrass Ensiled at Various Moisture Contents and the Subsequent Effects on Nitrogen Utilization by Sheep |
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H. V. Nguyen, M. Kawai, J. Takahashi, S. Matsuoka |
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| Abstract |
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The effect of various moisture contents of fresh forage on the change in nitrogen (N) fractions, in vitro ruminal N degradability, and the subsequent N utilization of silage in sheep were evaluated. Orchardgrass (Dactylis glomerata L.) with high (HM, 76%), medium (MM, 65%) and low (LM, 40%) moisture contents were ensiled into silos of 120 L capacity for 120 days. A nitrogen balance trial was conducted using a 4횞4 Latin square design consisting of four dietary treatments (i.e. fresh forage, HM, MM and LM silages) and four wethers. With respect to N fractions, fraction 1 (buffer solution soluble N), fraction 2 (buffer solution insoluble Nneutral detergent insoluble N), fraction 3 (neutral detergent insoluble N-acid detergent insoluble N), and fraction 4 (acid detergent insoluble N) were determined. The proportion of fraction 1 in silages tended to decrease, while the in vitro ruminal degradability of insoluble N increased (p<0.05) with lower moisture contents at ensiling. Consequently, nitrogen utilization in sheep tended to improve as the moisture content of ensiled grass was decreased, with a negative correlation (p<0.01) between urinary N and the in vitro ruminal degradability of insoluble N. The averaged N retentions for HM, MM, and LM silage treatments were 59, 73 and 79% of that for fresh forage, respectively. |
| Keywords:
Orchardgrass; Moisture Contents; Ensiling; Nitrogen Fractions; Ruminal Degradability; Nitrogen Utilization |
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