Type of Document Master's Thesis Author Tomlinson, Dana J. URN etd-06122012-040012 Title Effect of varying levels of neutral detergent fiber and total digestible nutrients on dry matter intake of dairy heifers Degree Master of Science Department Dairy Science Advisory Committee
Advisor Name Title James, Robert E. Committee Chair McGilliard, Michael L. Committee Member Stallings, Charles C. Committee Member Vinson, William E. Committee Member Keywords
Date of Defense 1988-05-12 Availability restricted AbstractOne hundred and eight Holstein dairy heifers were divided into two weight blocks based
on beginning body weight (E = < 182 kg, light, > 270 kg, heavy). Heifers within weight
blocks were randomly assigned to one of five treatments. Treatments consisted of three
levels of NDF (35%, 45%, 55%) at 100% ofNRC TDN recommendation, and three levels of TDN (85%, 100%, 115 of NRC) at 45% NDF for light heifers. For heavy heifers, treatments consisted of three levels of NDF (40%, 50%, 60%) at 100% NRC
TDN, and three treatments with similar levels of TDN at 50% NDF. Heifers were fed total mixed rations of corn silage, alfalfa haylage, ground orchardgrass hay, soybean meal, high moisture corn and a mineral mix formulated for 0.68 kg ADG. Mean gains
(kg/d) were 1.07 and .96 for the light and heavy blocks, respectively. DMI as a percent
of BWT differed across NDF levels for light heifers (3r'= 2.96, 2.56, 2.57, 2.57, and 2.87
% of BWT for the low, med., high NDF, and low, high TDN treatments, respectively).
Heavy heifer DMI% did not differ (.¥= 2.45, 2.40, 2.24, 2.15, and 2.42 % ofBWT for
low, med., and high NDF, and low, high TDN treatments, respectively). Equations to
predict DMI were developed using intake information from this and a previous study.
Backward stepwise regression was utilized to generate a simplified model. Model selected was: DMI (kg/d) = -5.9781 + (2.2120E-05 * BWTSQ) - (5.5527 * GAIN) + (2.7837 * GAINSQ) + (0.4668 * NDF) + (5.3930 * NDFSQ) + (0.03285 * DM) +
1 (7.7859E-03 * BWT * GAIN);11 = 514, rz = .67.
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