| Popis: |
Nutritive value of corn silage harvested before and after frost was evaluated through 12 lactating Holstein cows during five 14-day periods in a feeding and digestibility trial. Silages from corn harvested at milk stage, dough stage, and after one, two, and six frosts were evaluated with control corn silage at dough stage. Concentrate feed made up 30% of the ration dry matter. Percentages of dry matter, neutral detergent fiber, acid detergent fiber, acid detergent lignin, nitrogen, phosphorus, potassium, calcium, and magnesium varied among silages. There was no significant difference of dry matter intake or of nutrient digestibility of the control silage among the five periods, indicating no time change. Production of 4% fat-corrected milk decreased steadily 9% per mo. For milk stage, dough stage, and after one, two, and six frosts, respective intakes of dry matter were 15.1, 16.3, 14.9, 16.6, 14.7 kg/day; 4% fat-corrected milk yields were 17.7, 18.1, 17.8, 17.6, 17.5 kg/day; and milk fat was 3.5, 3.6, 3.4, 3.2, and 3.3%. The partitioning of energy, nitrogen, calcium, phosphorus, potassium, and magnesium favored the feeding of corn silage harvested after two frosts. Apparent digestibilities of dry matter, energy, and nitrogen were reduced by frost for corn harvested as silage after frost. |
