Date of Graduation


Document Type


Degree Name

Master of Science in Animal Science (MS)

Degree Level



Animal Science


Kenneth Coffey

Committee Member

Elizabeth Kegley

Second Committee Member

Dirk Philipp

Third Committee Member

James Caldwell


Co-product Feedstuffs, Distiller's Grains, Limit-feeding, Rumen Function, Rumen Recovery, Soybean Hulls


In terms of energy density, the cost of shipping hay is often not justified in yr where adverse conditions limit available forage. Our objective was to determine if co-product feedstuffs could be used to meet the energy demands for cows in late pregnancy. Eighty-six crossbred cows (527 ± 0.8 kg BW) in late gestation were stratified by BW, BCS and age and allocated randomly to 1 of 6 groups held on 2-ha dormant bermudagrass pastures for 68 d. Three groups were offered bermudagrass hay ad libitum (HAY) and three groups were offered 6.4 kg of soybean hulls (LSH) daily and allowed access to mixed-grass hay for 1 h daily. Changes in BW, BCS, serum non-esterified fatty acids, and birth weights were minimal between treatments (P ≥ 0.12). In a companion study, 8 ruminally-fistulated cows (671 ± 32.0 kg BW) were stratified by BW and allocated randomly to1 of 4 treatments in a 2-period study: LSH, limit-fed distillers dried grains with solubles (LDG), a limit-fed mixture of SH and DDGS (MIX), or ad libitum mixed-grass hay (HAY). Total feces were collected for 5 d following a 28-d adaptation to diet and facilities in each period. Rumen fluid was sampled immediately prior to feeding and 2, 4, 6, 8, 10 and 12 hr post-feeding for ruminal fermentation assessment. Digestibility of DM, OM, aNDF and ADF was greater (P < 0.05) from limit-feeding than from those consuming hay. Individual VFA concentrations differed (P < 0.05) early in the day, but no difference existed beyond 8 h. In situ forage DM disappearance was reduced (P < 0.05) from LSH and LDG in comparison to HAY while diets were being fed. However, cows achieved steady-state forage disappearance within one week following removal from the diets. Based on this information, co-product feedstuffs may be used in lieu of hay to meet the energy requirements of cows during late pregnancy without adverse effects.