The physical condition of 20 resident Columbian black-tailed fawns (Odocoileus hemionus columbianus) from oak woodland and chaparral areas was evaluated during spring and fall, using a series of physical parameters: whole and field dressed weight, mandible and femur length, blood urea nitrogen level (BUN) and packed cell volume (PCV) of the blood, rumen fill, volatile fatty acids (VFA) in rumen fluid, and fat content of femur marrow and muscle tissue. The plant species composition of rumen contents was also determined. The physical condition of oak woodland fawns appeared better than that of chaparral fawns, as indicated by significantly higher ruminal VFA, BUN, femur marrow fat and muscle tissue fat levels in animals from the oak woodland, Femur marrow fat was accurately and consistently determined using a modified Babcock acid digestion procedure. Fat and dry matter content of femur marrows were highly correlated. Seasonal differences in the diet of oak woodland fawns were observed, while chaparral fawns relied heavily on browse both in spring and fall. Based on age estimates from eye lens and body weights, fawns in the oak woodland were born 18 days earlier than those in chaparral.
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