THE EFFECT OF PLANTING DENSITY ON THE NUTRITIVE VALUE OF CORN SILAGE FOR LACTATING COWS

Abstract
A late-maturing corn hybrid, Funk brand G4444, was planted in 2-ha plots at 60 000 plants per hectare (low density) and at 100 000 plants per hectare (high density). At harvest, the dry matter and ear contents were 24.2 and 34%, respectively, for the low-density treatment and 22.8 and 28%, respectively, for the high-density treatment. Two groups of 10 lactating cows were used to compare the nutritive value of the ensiled forages over a 10-wk feeding period. Silage dry matter intake, milk yield and milk fat content were 10.33 kg/day, 27.11 kg/day and 3.52% for the cows fed high-density silage compared to 11.79 kg/day, 31.88 kg/day and 2.91% for those fed the low-density silage. Feeding the low-density silage resulted in a decreased level of acetic acid in the rumen and an increased level of propionic acid. Blood hematocrit and plasma calcium levels were lower for cows fed the silage from the low-density planting. Dry matter digestibility of the complete ration was 72.5 and 71.8% for the high- and low-density plantings, respectively. It was concluded that an increased ear content of approximately 10 percentage units resulted in a corn silage which was consumed more readily, altered rumen fermentation and caused a decrease in milk fat content. Key words: Corn silage, lactating dairy cows, planting density

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