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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Phenotypic Characterization of Feed Efficiency and Feeding Behavior Traits in Performance Tested Bulls Fed a Corn Silage-Based Diet

Moreno Rajo, Jose Gilberto 02 October 2013 (has links)
Objectives of this study were to characterize feed efficiency traits and examine phenotypic relationships with feeding behavior traits in bulls. Performance, feed intake and feeding behavior traits were measured in bulls (n = 5,165) representing 2 breeds (4100 Angus and 952 Red Angus). Intake and feeding behavior traits were measured for 70-d using a GrowSafe system while fed a corn silage based diet (ME = 2.50 Mcal/kg DM). BW was measured at 14-d intervals. Residual feed intake (RFI) was calculated as the difference between actual DMI and that expected from regression of DMI on mid-test BW0.75 (MBW) and ADG, and residual gain (RG) as the difference between actual ADG and that expected from regression of ADG on MBW and DMI. Residual gain and intake (RIG) was computed as the sum of -1 x RFI and RG, both standardized to a variance of 1. Results from the study indicate that RFI was correlated with DMI (r = 0.71, P < 0.0001) but not MBW or ADG, whereas, RG was correlated with ADG (r = 0.87, P < 0.0001) but not MBW or DMI. RFI was negatively correlated with G:F (r = -0.53, P < 0.0001) and RG (r = -0.40, P < 0.0001). Feeding bout (FB) frequency and duration were correlated with RFI (r = 0.30, 0.36; P < 0.001), but were not significant or weakly correlated (r < 0.10) with RG and G:F. Meal criterion and duration were both correlated (r = -0.13, 0.22; P < 0.0001) with RFI, but not with RG or G:F. Bulls with low RFI spent less time at the feed bunk (129 vs 151 ± 31.2 min/d) and had fewer FB events (79 vs 91 ± 23.4 events/d) than high-RFI bulls. Low-RFI bulls had longer (P < 0.001) meal criterion (9.9 vs 8.5 ± 6.6 min) indicating they took longer to initiate new meals, and had longer meal durations (223 vs 244 ± 43.5 min/d) than high-RFI bulls. Bulls have distinctive feeding behavior patterns that contribute to between-animal variation in RFI, but not associated with RG or G:F.

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