Consumption of Corn Silage Dry Matter by Bred Heifers and Its Correlation with Subsequent First-Lactation Production1,2

Abstract

Twenty Brown Swiss, 28 Holstein, 25 first-generation, and 14 second- and third-generation crossbred heifers were fed all the corn silage they would consume during a 28-day experimental period. The silage was supplemented with 0.65 or 0.68kg of soybean oilmeal per day and salt free-choice. Regression coefficients between the log of average weight, and logs of average daily intake of silage and dry matter for the 28-day period were 0.49 (P<0.001) and 0.34 (P<0.05), respectively. The model used to analyze the data included breed group, W0-49, per cent dry matter, days pregnant, and season. All except season significantly affected (P<0.01) silage and dry matter intake. Least-squares means of daily intake of silage and dry matter adjusted for all significant factors were used to compare breed groups. Both groups of crossbreds consumed more silage and dry matter than the Brown Swiss or Holsteins. The second- and third-generation crossbreds showed significant heterosis for the consumption of silage.Correlations between adjusted dry matter intake for the 28-day period and milk and milk constituents produced in the first lactation were inconsistent from one breed group to another, and none of them was significant.