Title page for ETD etd-07082004-152844


Type of Document Master's Thesis
Author Rossini, Katherine Lynn
Author's Email Address krossini@vt.edu
URN etd-07082004-152844
Title Effects of Calfhood Respiratory and Digestive Disease on Calfhood Morbidity and First Lactation Production and Survival Rates
Degree Master of Science
Department Dairy Science
Advisory Committee
Advisor Name Title
McGilliard, Michael L. Committee Chair
James, Robert E. Committee Member
Pearson, Ronald E. Committee Member
Swecker, William S. Jr. Committee Member
Keywords
  • calfhood disease
  • age at first calving
  • mortality
  • morbidity
Date of Defense 2004-06-24
Availability unrestricted
Abstract
Calf health data and first lactation records for 2556 cows born in a commercial dairy herd between June 1998 and June 2001 were studied to determine the effects of calfhood disease on survival and performance. Operator-treated respiratory disease occurrences within the first year of life and digestive disease occurrences within the first 45 d of life were analyzed to determine their effects on calfhood morbidity, age at first calving, 305-d first lactation production, and mortality in first lactation. Of the 2556 records used, 2083 calves contracted respiratory or digestive disease at least once, 1254 calves had digestive disease only, 771 had respiratory disease only, and 191 calves had both diseases. Occurrence of calfhood digestive disease increased the chance of calfhood respiratory disease 2-fold. Age at first calving increased 0.53 mo with multiple occurrences of respiratory disease versus none. Calves born in the winter calved at 25.4 mo, whereas calves born in spring calved at 24.5 mo. Respiratory disease had the largest effect on calves born in the spring, resulting in 23.9 mo age at first calving for no occurrence and 25.4 mo for multiple occurrences. No significant effect of disease was detected for 305-d milk yield, fat yield, or SCC, but protein yield decreased by 0.05 kg/d with increased calf respiratory disease. Although calfhood disease had no influence on illness as a cow, disease-free calves had a 5% advantage in probability of remaining in the herd through 305-d, and an 8% advantage at 730-d compared with calves with 2 or more disease occurrences. In conclusion, calfhood occurrences of respiratory and digestive disease had a slight impact on age at first calving, depending on season of birth, and minimal impact on production performance through 305-d of first lactation. The occurrence of respiratory or digestive disease caused a decrease in survival rate from calving through 305-d in first lactation and 730 d after calving.
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