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Variables Associated with Peripartum Traits in Dairy Cows. VIII. Hormonal Profiles Associated with Dystocia¹

Purdue University⁵, West Lafayette, IN 47907

Abstract

Cases of dystocia (DYS; birth assistance after 2 hr of unassisted labor) among Holstein cows (n = 100) and heifers (n = 78) were identified over a 19-month period. The purpose was to determine the relationship between DYS and blood plasma concentrations of hormones from 9 days prepartum to 2.5 days postpartum. Cases of DYS were classified either as "malpresentation" (n = 15) or "normal presentation" (n = 27) and compared with peers with no dystocia (controls). Individual peers were matched with each case of DYS for parity, season of calving, health problems, prepartum diet, gestations shorter than 275 days and longer than 283 days and calf sex (partially matched). Differences in partum traits and hormone concentrations prepartum between cases of malpresentation DYS and controls were not distinguishable. Cases of normal presentation DYS were further subdivided on the basis of calf birth weight (CBW) as a percentage of the dam's postpartum bodyweight (CBW x 100/dam weight, CBW%) in an attempt to distinguish between anatomical DYS and physiological DYS. This procedure created two groups, DYS-H (dystocia with high CBW%, n = 10) and DYS-L (dystocia with low CBW%, n = 17), wherein the CBW percentage of every case of DYS-H was larger than that of any control animal. Plasma concentrations of prolactin only tended to be lower prepartum (P>.10) and peripartum (P<.10) in all cases of DYS (n = 42) than in controls (n = 42). Differences between day means in plasma concentration of estrone, estradiol–17β (Eβ) and estradiol–17 (E), but not progesterone (P4), were greater in DYS-H animals than in controls. However, these differences were almost completely eliminated by adjustment for the positive independent linear effects of CBW (P<.05) and dam weight (P>.10). These results imply that most cases of DYS-H were in fact due to anatomical incompatibility between the dam and fetus, especially since deviate hormonal profiles were observed for DYS-L. These deviations for DYS-L animals versus controls were higher (P<.05 to P<.01) unadjusted P₄ and E concentrations peripartum and lower (P<.05) adjusted Eß concentrations 2 to 5 days prepartum. Defects in at least two hormonal parameters were observed in 76% of DYS-L animals during the last 2 days prepartum, compared with 21% in normal presentation controls and DYS-H (P<.01).

¹ Journal Paper No. 8077, Purdue Univ. Agr. Exp. Sta. A contribution to NC-113, entitled "Methods for Improvement of Fertility in Cows Postpartum." This research was supported in part by a grant from the Indiana Farm Bureau Cooperative Association, Inc.

² 3300 Carpenter Road SE, #85, Olympia, WA 98503.

³ 6600 Whispering Hills Drive, Evansville, IN 47712.

⁴ Dept. of Anim. Sci., Washington State Univ., Pullman 99164.

⁵ A contribution from the Dept.of Anim. Sci.