Feeding Value of a High Oil Variety of Sunflowers as Silage to Lactating Dairy Cows

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Abstract
Whole-plant sunflowers (oilseed) [H. annuus] were chopped and stored as silage and compared to corn silage as the sole forage to 20 lactating Holsteins in a switch-back design of three 5-wk periods. Cows fed sunflower silage produced less milk (22.4 vs. 20.5 kg/day) but similar amounts of 4% fat-corrected milk. Cows fed sunflower silage had greater fat, less protein and less total solids in milk. Cows consumed 4.0 kg/day less dry matter from sunflower silage than from corn silage. Oleic and linolenic increased and myristic and palmitic fatty acids decreased in milk fat from cows fed sunflower silage. Cholesterol in serum (mg/dl) was 321 and 160 for cows fed sunflower silage and corn silage. Cows fed sunflower silage had higher molar percentage of acetate, isobutyrate, isovalerate and a wider acetate propionate ratio with concomitant lower molar percentage of propionate, butyrate, valerate and less total acids in rumen fluid than cows fed corn silage. Rumen fluid pH was 6.98 and 6.83 for cows fed sunflower silage and corn silage. Acceptable quality silage can be made from whole oilseed sunflowers. For maximum milk production, sunflower silage should not be fed as the only forage to dairy cows.