| Five experiments were performed to characterize the nutrient availability of a high caloric density diet from corn-sunflower intercropped silage. (1) Four cows in a digestion trial were used to determine silage nutrient composition digestibilities of an early and a late variety planted at 50,000, 75,000, 100,000 and 150,000 plants/ha. (2) Thirty six lactating cows in a lactation trial were used to evaluate milk production and composition of cows fed an early and a late corn variety planted at 50,000 and 150,000 plants/ha. (3) Silage from three treatments of corn, sunflowers, and 9 combinations of corn-sunflower intercropping were used to evaluate nutrient chemical composition. (4) Six non-lactating cows were used to evaluate corn, sunflower and corn-sunflower intercropping silage nutrient in vivo digestibility, followed by a (5) lactation trial with 30 cows to evaluate milk production, composition, rumen fermentation, blood metabolites, and milk fatty acid composition. In the in vivo digestion trial for corn populations, the early variety planted at 150,000 and the late variety planted at 50,000 plants/ha had the highest dry matter digestibility. The early variety planted at 150,000 yielded 1.25 tons more of digestible dry matter/ha, which resulted in greater milk productions. However, feed efficiency was higher for the late variety planted at the highest density. Silage field evaluation evidenced that corn-sunflower silage had similar fiber composition to corn with double the caloric density. Digestion trials suggested that fiber digestion was not affected by high concentrations of vegetable oils in the corn-sunflower silage, and in the lactation trials with intercropped silages, cows fed corn or corn-sunflower had similar milk productions, with cows fed corn-sunflower consuming 7% less feed. Milk of cows fed corn-sunflower silage had higher proportions of polyunsaturated fatty acids compared to cows fed corn silage. Data presented in this study show evidence that corn-sunflower silage has a potential as a source of energy in diets of dairy cattle. |
