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Six mature geldings of light horse breeds (557 ± 37 kg) were randomly assigned to a nontoxic endophyte-infected tall fescue hay (n = 3) or pasture treatment (n = 3) in a crossover design with 14-d periods to estimate DMI with alkane markers and to compare DMI of hay and pasture. When fed pasture, horses were housed in stalls from 0700 to 1300 h daily with access to water and then grazed pasture as a group in a single 0.4 ha pasture from 1300 to 0700 h. When fed hay, horses were maintained individually in stalls and given access to hay ad libitum from 1300 to 0700 h. All horses were individually fed 225 g oats twice daily treated with hexatriacontane (C36; external marker) and fecal samples were collected at 0700 and 1900 h on d 10 to 14. Fecal samples were mixed, dried, subsampled, and analyzed for tritriacontane (C33) and hentriacontane (C31) as internal markers and C36 as the external marker using gas chromatography. Estimated hay DMI using either C33 (1.75 kg/100 kg BW) or C31 (1.74 kg/100 kg BW) as internal alkane marker did not differ (P = 0.55) from measured hay DMI (1.70 kg/100 kg BW). Pasture DMI and DM digestibility (DMD) estimated with C31 (2.24 kg/100 kg BW and 53.1 g/100 g DMI) or with C33 (2.34 kg/100 kg BW and 56.2 g/100 g DMI) was greater (P = 0.05) than hay DMI and DMD (1.74 kg/100 kg BW and 44.5 g/100 g DMI). Intake estimated with C33 or C31 did not differ (P = 0.35) during hay or pasture. In conclusion, alkanes can be used to estimate pasture or hay DMI and DMD, and pasture intake exceeded hay intake when offered ad libitum.

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The objective of the study was to determine if relationships exist with feeding behaviors of bucks, rams, and bulls and efficiency or residual feed intake (RFI). Animals utilized in this investigation were either producer consigned by species or West Virginia University animals. All animals were group-housed in pens (14.6 m x 51.2 m) with 156.2 m 2 under roof at the Reymann Memorial Farm in Wardensville, WV over two years. Animals were fed complete nutritionally adequate rations ad libitum to meet daily growth requirements for each species. GrowSafe radio frequency technology (GrowSafe Systems Ltd.) was used to monitor animal identification, visit time and location, duration, and feed displacement. Allflex® transponders were placed in each animal's left ear. Eight pens had three feed nodes, while two pens had four. Rams and bucks were housed in the pens with four feed nodes. Modifications were made to the feed nodes for the ram and buck research to prevent more than one animal from feeding at one time. Statistical analyses were completed using Proc FREQ, TTEST, and GLM of SAS. More efficient animals consumed less feed (P < 0.01) and visited the feed nodes less frequently (P < 0.01). Negative RFI goats and the rams in the first year had fewer feeding and nonfeeding bouts (P < 0.05). Most visits occurred during the day (P < 0.01) for all species. Daily feed intake varied in all species (P < 0.01). Individual differences were seen in each species with other behaviors and performance measurements. Although behavioral differences were seen with RFI in all species, a more complete behavioral analysis is required to understand how dominance behavior and behavior allocation affect energy expenditure and intake. iii ACKNOWLEDGEMENTS I begin by thanking Dr. Eugene Felton for giving me the opportunity to work as one of his graduate students and expanding my horizon in animal science. Previously having minimal experience with beef cattle, my experience at West Virginia University has opened a new window of opportunities. Also, I thank Dr. Janet Tou for her guidance and leadership while preparing to further my education after my studies at West Virginia University along with the many faculty members that have provided constructive criticism to help shape my way of thinking and develop ideas pertinent to a career in animal science. The graduate students in the department of animal and nutritional sciences are greatly appreciated for all their guidance and assistance over the past two years. Finally, I thank my family and friends for their support.