Results and Discussion
Ewes fed soybean hulls lost more than twice as much weight during the trial (Table 2) than those fed supplemental corn (P < 0.06). Although the interaction was not significant (P = 0.37), ewes fed 1.5 lb of soybean hulls lost 1.8 times more weight than those fed 1.5 lb of corn, while those fed 3 lb of soybean hulls lost 2.7 times more weight than those fed 3 lb of corn. Despite our hypothesis that associative effects might narrow the effective energy value of these feeds, clearly corn had a substantially higher energy value than soybean hulls. One would have expected negative associative effects of corn would be worse at the higher supplementation rate. This did not occur; weight loss was similar between the 1.5 and 3.0 lb supplementation rate of corn. Ewe body condition score changes followed the same trends as was observed for body weight. Feed intake was not a dependent variable. Feed intake was established at a 10% lower rate for ewes fed the higher amounts of supplemental energy because the corn and soybean hulls are higher in energy than haylage. Lamb performance and creep intake was not affected (P > 0.30) by diet fed to the ewes.
In summary, soybean hulls and corn can be used successfully as energy supplements in alfalfa based lactation diets. Associative effects of source of energy were not measurable. In formulating lactation rations, the source of energy is not of importance as long as energy intake is sufficient to meet the calorie requirements of the animal.