Using whole cottonseed to replace dried distillers grains plus solubles and prairie hay in finishing beef cattle rations balanced for physically effective neutral detergent fiber

Objective: The objective of this experiment was to determine the effects of replacing prairie hay and dried distillers grains plus solubles with whole cottonseed (WCS) in diets balanced for physically effective NDF on the growth, intake, feed efficiency, carcass characteristics, and plasma metabolites of finishing beef cattle. Materials and Methods: Crossbred heifers (n = 103) and steers (n = 104) were blocked by BW within sex and randomly allocated to pens within block (6 pens per treatment) with 17 (n = 10 pens) or 18 (n = 2 pens) animals per pen. Pens were randomly allocated to experimental treatment: either a control diet (CON; prairie hay, dried distillers grains plus solubles, dry-rolled corn, and liquid supplement) or a WCS diet (CTN; WCS, dry-rolled corn, and molasses). A common vitamin and mineral supplement and urea were included in both diets at the same rate. Animals were slaughtered in 3 groups based on BW block. Results and Discussion: Cattle fed the CTN treatment tended to have a greater final BW (P = 0.10) and had greater overall ADG and G:F (P = 0.05). There was no difference in overall DMI (P = 0.23). Fecal consistency scores were greater for cattle fed the CON treatment on d 42, at the beginning of the ss-agonist feeding period, and at the final collection before slaughter (P <= 0.03). Cattle fed the CTN treatment had a more neutral fecal pH on d 140 and at the final collection (P < 0.01). No treatment x day interactions (P >= 0.70) were detected for plasma glucose, lactate, urea nitrogen, or nonesterified fatty acid concentrations. Cattle fed the CON treatment had greater plasma urea nitrogen concentrations (P < 0.001) and a tendency for a greater plasma lactate concentration (P = 0.06). A day effect was also observed for all plasma metabolites (P < 0.001). Implications and Applications: This experiment suggests that feeding WCS improves the growth and feed efficiency of cattle when replacing the roughage and byproduct protein and fat sources within a finishing diet.