J. Anim Sci., doi: 10.2527/jas.2006-467
©Copyright, 2007, The American Society of Animal Science
Effect of a saponin-based surfactant and ageing time on ruminal degradability of flaked corn grain dry matter and starch
A. N. Hristov 1*,
S. Zaman 1,
M. VanderPol 1,
P. Szasz 1,
K. Huber 2,
D. Greer 3
1 Department of Animal and Veterinary Science, University of Idaho, Moscow, ID
2 Department of Food Science and Toxicology, University of Idaho, Moscow, ID
3 AgriChem, Inc., Ham Lake, MN
* To whom correspondence should be addressed. E-mail: ahristov{at}uidaho.edu.
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Abstract |
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The objectives of this study were to investigate the effect of a saponin-based surfactant, Grain Prep surfactant (GP), and hot flake ageing time on starch characteristics and ruminal DM and starch degradability of steam-flaked corn grain. In 2 experiments, the moisture content of incoming corn was automatically adjusted using the Grain Prep Auto Delivery System to moisture contents of 19.8% (Exp. 1) and 18.5% (Exp. 2). The application rate of GP was 22 ppm (as is basis). Control corn was treated with water alone. Processed corn in Exp. 2 was stored in insulated containers for 0, 4, 8, and 16 h. Flaked corn samples were incubated in the rumen of lactating dairy cows for 0, 2, 4, 6, 16, and 24 h. In Exp. 1, GP increased, compared with the control, the soluble fraction and effective degradability (ED) of DM by 17.2 and 8.6%, respectively. The ED of cornstarch was increased by 6.7%. In Exp. 2, the concentration of soluble DM and starch were increased by GP by 15 and 24% compared with the control. The ED of DM and starch were also increased by 3 and 4%, respectively. No differences in gelatinization temperatures were observed due to treatment, except GP-treated grain had a slightly greater mean gelatinization enthalpy in Exp. 2. In a pilot study, DM degradability parameters were not affected by germination of the corn kernels. Ageing of the hot flakes for up to 16 h resulted in a quadratic decrease in DM and starch ruminal degradability. The ageing process impacted starch gelatinization enthalpy values of flaked grain in a manner inverse to that observed for ruminal DM and starch degradation. This phenomenon was most likely explained by increased starch intra-molecular associations or crystallinity associated with starch annealing or both. This study confirmed our previous observations that Grain Prep surfactant increases flaked corn DM and starch degradability in the rumen. As rate of degradation was not affected by the surfactant, the increase in degradability was attributed mainly to increases in DM and starch solubility.
Key Words:
corn grain, grain processing, in situ, saponin
