This is a draft schedule. Presentation dates, times and locations may be subject to change.
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Additional Excercise Among Grazing Dairy Cows and Effects on Uterine Artery Blood Flow, Milk Production, and Milk Quality Parameters
Additional Excercise Among Grazing Dairy Cows and Effects on Uterine Artery Blood Flow, Milk Production, and Milk Quality Parameters
Tuesday, July 11, 2017
Exhibit Hall (Baltimore Convention Center)
It is expected that grazing animals take more steps per day than those housed in free stall, confinement barns. The aim of this study was to determine if additional exercise in grazing, lactating dairy cows affected milk production, milk quality, and uterine artery blood flow during late gestation. On d 180 of their gestation, 17 (all conceived on 1 of 2 dates within 2 wk and averaged 326 DIM) Holstein cows in a grazing production system were randomly assigned to 1 of 2 treatment groups: an exercise group (WALK; n=9) which was walked an additional 5.6 km per d and a control group (CON; n=8) which was not walked more than normal. Cows were fitted with pedometers to record steps; data were collected daily. All animals were housed together on ryegrass pasture with a concentrate supplement. All animals were milked twice daily until the dry off period (d 223 of gestation), milk yield was recorded at each milking, and milk samples (morning and afternoon) were collected on d 180 and 210 of gestation to evaluate milk composition. Ultrasound exams were conducted on d 180, 210, and 240 of gestation to measure heart rate and uterine artery blood flow. The MIXED procedure of SAS (SAS Institute Inc., Cary, NC) was used. Least-square means and pooled standard errors are reported. The number of steps taken were greater (P ≤ 0.0001) between cows in the WALK group (7,212 ± 208 steps per d) compared to the CON group (5,637 ± 221 steps per d). The number of steps also differed (P < 0.0001) between d 210 and d 240 of gestation (7,317 ± 166 and 5,532 ± 166 steps per d, respectively). Treatment did not affect (P > 0.05) heart rate or total uterine artery blood flow. Heart rate was greater (P < 0.0001) in cows at d 210 of gestation (89.6 ± 1.61 beats per min) compared to d 240 (73.4 ± 1.61 beats per min), although total blood flow did not change (P = 0.31) between those time points in gestation. Milk yield as well as concentrations of fat, protein, and lactose were not different (P > 0.05) between treatments. Somatic cell counts and milk urea nitrogen did not differ (P > 0.05) between treatments. In conclusion, added exercise during late gestation did not impact cardiac or milk measurements in this study.