PRESENTED AT ASAS Midwestern meeting, March, 19th, 2002, Des Moines, Iowa
Iron bioavailability of humate* in young pigs
S.
W. Kim*, L. E. Hulbert, H. A. Rachuonyo, and J. J. McGlone
Texas
Tech University, Lubbock
Humate is derived from mineral humic substances that include several biological active and inactive compounds which is commonly used for improving soil fertility. Use of humate in swine diets is a relatively new concept. A series of research projects has been conducted to evaluate the efficacy of humate as a feed additive for swine. As a first approach, a study was conducted to test the bioavailability of iron in humate for nursery pigs. Humate contained 8,700 ppm of iron by atomic absorption spectrophotometry. One hundred fifty pigs (Newsham, Colorado Springs, CO) were not given supplemental iron while nursing for 21 d. Pigs were weaned on d 21 and allotted to five treatments (four control treatments with different levels of supplemented iron; 0, 12, 54, and 69 ppm from FeSO4 and one treatment with 88 ppm iron from humate). Pigs were fed diets for 5 wk ad libitum and water was accessible freely. Body weight and feed intake were measured weekly. Blood samples were taken from pigs on d 28 for measuring number of red blood cells and hemoglobin concentration. Pigs fed a diet with the humate grew faster (P < 0.05) during the first week postweaning, but performance was not different during the entire period. Feed intake and gain:feed ratio were the same among treatments. Slope ratio technique was used for the data analysis. The concentration of blood hemoglobin did not respond to dietary iron levels using this model. However, the number of red blood cells (106/µL) was modeled by 4.438 + 0.017 x ‘Fe (ppm) from FeSO4’ + 0.012 x ‘Fe (ppm) from the humate’. Based on the comparison between the slopes (0.012/0.017), iron in humate was 71% as available as the iron in FeSO4. However, there was no difference between the slopes for dietary FeSO4 and humate iron (P > 0.05). Humate can replace FeSO4 as an alternative iron source for pigs at 71% relative bioavailability.
KEY WORDS: Nursery Pigs, Iron, Bioavailability, Humate
* Product name: PROMAX, from Humatech, Inc., Houston, TX.