Effects of diet type and metabolizable energy intake on tympanic temperature of steers fed during summer and winter seasons

Arias Inostroza, Rodrigo - Mader, T. L. - Parkhurst, A. M.
Datos de publicación:
JOURNAL OF ANIMAL SCIENCE,Vol.89,1574-1580,2011
body temperature - cattle - fiber - metabolizable energy - season - thermal stress
A summer study and a winter study were conducted using an incomplete factorial structure in a complete randomized design. Within season, the factors studied were 1) type of diet, which included 2 levels of ME, classified as either concentrate (3.04 Mcal of ME/kg) or roughage (2.63 Mcal of ME/kg) diets, and 2) daily ME intakes (MEI) of 11, 18, and 25 Mcal of ME/d for the roughage diets and 18, 25, and 32 Mcal of ME/d for the concentrate diets. In Exp. 1 (summer study), 30 steers (5 steers/treatment combination) were used to collect tympanic temperatures (TT). In Exp. 2 (winter study), 24 steers (4 steers/treatment combination) were used to collect TT. Mean TT was 0.3 degrees C greater for summer than winter (38.9 vs. 38.6 degrees C, respectively; P < 0.05). Steers fed diets based on concentrate tended to display greater TT than steers fed diets based on roughage. Season x diet x hour interactions were found for TT (P = 0.01). In the winter, greater TT (P < 0.05) were found from 0900 to 1400 h when an equal amount of MEI was derived from a concentrate-based vs. roughage-based diet. In cattle fed roughage-based diets during the summer, TT = 38.63 + 0.0114.MEI, whereas for cattle fed concentrate-based diets, TT = 38.69 + 0.0114.MEI. During the winter, for cattle fed a roughage-based diet, TT = 37.65 + 0.0856.MEI 0.0018.MEI2, whereas for cattle fed a concentrate-based diet, TT = 35.37 + 0.2635.MEI 0.0051.MEI2. In summary, results demonstrate that increases in the energy of the diet resulted in increases in TT. However, the response was dependent on season of the year, with a linear response in TT for summer and a quadratic response during winter.

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