

Type of Document Master's Thesis Author Byrd, Bridgett McIntosh Author's Email Address brbyrd@vt.edu URN etd-12032003-140008 Title Alkanes as Internal and External Markers in Horses and the Digestibility of a High Fat Cereal By-Product Degree Master of Science Department Animal and Poultry Sciences Advisory Committee
Advisor Name Title Kronfeld, David S. Committee Chair Abaye, Azenegashe Ozzie Committee Member Ordakowski-Burk, Amy L. Committee Member Sklan, David S. Committee Member Splan, Rebecca K. Committee Member Keywords
- horse
- dry matter intake
- fecal output
- alkanes
- markers
- digestibility
Date of Defense 2003-11-13 Availability unrestricted Abstract Determining intake of feeds in horses is an important factor in incorporating supplements in their diets. Fecal recoveries (R), fecal output (FO), dry matter digestibility (DMD) and dry matter intake (DMI) were estimated using alkanes as markers in 8 thoroughbred geldings. The experiment compared two diets in a 2 X 2 latin square experiment. The diets were mixed grass hay only (H) and the same hay plus a cereal by-product (H + CBP). The cereal by-product (CBP) was the high fat component added to feeds at Virginia Tech's Middleburg Agricultural Research and Extension Center. The apparent digestibility of ether extract (EE) and other nutrients in the H and H + CBP, as well as the partial digestibility of CBP were also determined. The periods were 21 d each with a dietary accommodation period followed by eight days of dosing the even chain alkanes dotriacontaine (C32) and hexatriacontane (C36) as external markers. Total collection (TC) was performed the last 4 d of dosing.The results show that mean recoveries of alkanes were close to 100%, but the range for individual alkanes was wide, and the pattern of recoveries for alkanes of different chain length was inconsistent from feed to feed. The results also indicate that mean estimates of the DMI, DMD and FO of a feed, such as H or H + CBP, are determined with reasonable accuracy by means of alkane markers. In contrast, alkane estimates of DMI and DMD in an individual horse fail to predict corresponding TC estimates. The alkane estimate of FO in an individual horse predicts a TC value with error of 16.4%. The CBP was found to be an excellent source of EE, CP and fiber but a poor source of Ca.
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