title: Exercise training of late-pregnant and nonpregnant dairy cows affects physical fitness and acid-base homeostasis.
abstract: The objective was to determine if exercise training improves physical fitness of nonlactating, late-pregnant and nonpregnant multiparous Holstein cows and alters acid-base homeostasis during an exercise test on a treadmill. Twenty-six pairs (each pair having 1 late-pregnant and 1 nonpregnant) of cows were assigned to treatments of exercise training or no exercise. Exercise training was walking (1.25 to 1.5 h at 3.25 km/h) every other day in an outdoor mechanical walker for 70 d. Cows completed treadmill exercise tests on d 0, 30, and 60 of the experiment or about d 70, 40, and 10 before expected parturition of the pregnant cow of each pair. On d 0, physical fitness was similar among all cows based on durations of treadmill tests, heart rates, and acid-base measurements at given workloads (21.1 +/- 0.6 min; 144 +/- 2.2 beats per min; plasma lactate 3.1 +/- 1.9 mmol/L; and venous blood pH 7.44 +/- 0.0035, respectively). After 60 d of training, exercised cows walked longer during treadmill exercise tests compared with nonexercised cows (23.7 vs. 18.3 +/- 0.85 min, respectively), indicating greater physical fitness (pooled across pregnancy status). Heart rates and plasma lactate concentrations at given workloads were less (144 vs. 156 +/- 2.7 beats per min; and 1.4 vs. 3.2 +/- 0.24 mmol/L for exercised compared with nonexercised cows, respectively). Additionally, exercised cows more effectively maintained acid-base homeostasis during treadmill tests compared with nonexercised cows. Metabolic, endocrine, and nutritional demands associated with late pregnancy did not affect responses differently to exercise training for late-pregnant compared with nonpregnant cows. Overall, exercise training of late-pregnant and nonpregnant cows for 60 d improved physical fitness.
authors.affiliation: Department of Animal Science, Michigan State University, East Lansing 48824, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Davidson
authors.forename: D K
authors.initials: DK
authors.lastname: Beede
mesh_terms: D000136:Acid-Base Equilibrium / Q000502:physiology*; D000818:Animals; D001639:Bicarbonates / Q000097:blood; D002245:Carbon Dioxide / Q000097:blood; D002417:Cattle / Q000097:blood / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000097:blood; D010805:Physical Conditioning, Animal; D011188:Potassium / Q000097:blood; D011247:Pregnancy; D011897:Random Allocation; D013997:Time Factors
chemical_list: D001639:Bicarbonates; D006454:Hemoglobins; D002245:Carbon Dioxide; D019344:Lactic Acid; D011188:Potassium