Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 7/21/2002
Publication Date: N/A
Technical Abstract: The prepartum milking of dairy heifers may be beneficial to postpartum production performance through the acclimation of heifers to the milking parlor, and has been shown to improve postpartum heifer udder health (e.g., reduced uddder edema). The objective of this study was to determine if the prepartum milking of dairy heifers would improve postpartum reproductive health, as determined by rates of uterine involution, ovarian follicular development and the resumption of estrous cycles. Pregnant heifers (Holstein, n = 21, Jersey, n = 10) were assigned to either a prepartum milked (pre-milked; n=15) or control (n = 16) treatment group. Pre-milked heifers were milked twice daily starting 3 wks prior to anticipated calving dates. Control heifers were not milked or in the parlor until after calving. Following calving, measurements were taken 2x weekly to assess reproductive health and included palpation for uterine tone (1 = poor, 5 = excellent) and uterine position (0 = below pelvic rim; 2 = above pelvic rim/normal position), vaginal electrical conductance (VEC; relative units: RU), and the quantification of follicular development and cross-sectional area of the uterine horns (uterine difference) by transrectal ultrasonography. Blood serum samples were collected for progesterone (P4) analysis and quantified by RIA. Uterine tone, uterine position and uterine difference did not differ (P>.10) relative to treatment but changed over time (P<.0001) postpartum. VEC increased (P<.0001) from wk 2 (73.1+1.9 RU) to wk 9 (94.2+2.2 RU) postpartum, but also did not differ (P>.10) relative to treatment. Pre-milked heifers tended (P<.08; 2.5+.24) to have more large follicles at 30 d post-partum relative to controls (1.8+.26), while numbers of small- and medium-sized follicles did not differ (P>.10). Initiation of luteal activity (day in which two consecutive P4 samples were >1 ng/ml) did not differ (P>.10) between control (25.9+2.5d) and pre-milked (33.1+3.5d) heifers. Therefore, no overt differences in reproductive parameters were observed between the pre-milked and control heifers.