title: Short communication: Timing of first milking affects serotonin (5-HT) concentrations.
abstract: Hormonal signals differentially regulate the timing of parturition, as well lactogenesis and, potentially, colostrum formation in the mammary gland. Non-neuronal serotonin (5-HT) is a homeostatic regulator of the mammary gland. In the current study, we manipulated the timing of first milking to investigate its effects on serum 5-HT and calcium concentrations in the maternal and calf circulation, as well as in colostrum. Twenty-three cows were randomly assigned to a control (CON; n=10) group, milked for the first time at 4h postcalving, or a treatment (TRT; n=13) group, milked for the first time approximately 1 d before calving in addition to 4h postcalving. Maternal blood samples were collected for 4 d precalving, 3 times daily, and 1 blood sample was taken 4h postcalving. Calf blood samples were collected 4 (before first colostrum feeding) and 12h after birth, and at 3 wk of age. Calves from both treatments were fed colostrum from their respective mothers. Serum 5-HT concentrations were greater in CON cows and decreased significantly in TRT cows after milking was initiated precalving (951 vs. 524 ± 111 ng/mL, respectively). Cow serum calcium concentrations were affected by time, beginning to decrease 1 d precalving until 4h postcalving, but this drop in serum calcium was more pronounced in TRT cows. Serum 5-HT and calcium concentrations were negatively correlated (r=-0.57) for the CON cows and positively correlated (r=0.6) for the TRT cows. Maternal calcium and 5-HT decreased similarly due to precalving milking. Calcium and 5-HT concentrations were greater in colostrum collected from TRT cows milked precalving. Overall, calves had higher circulating 5-HT concentrations than cows, and calves born to TRT cows had increased 5-HT concentrations compared with the CON. Precalving milking could affect 5-HT synthesis within the mammary gland and therefore affect maternal 5-HT and calcium concentrations. Further research is needed in ruminants to assess the extent of 5-HT placental transfer, its role on pre- and postnatal development of the calf, the importance of its presence in colostrum, and potential long-term effects on calf health.
authors.affiliation: Department of Dairy Science, University of Wisconsin, Madison 53706.
authors.forename: J
authors.initials: J
authors.lastname: Laporta
authors.affiliation: Veterinary Physiology, Vetsuisse Faculty, University of Bern, CH-3001 Bern, Switzerland.
authors.forename: J J
authors.initials: JJ
authors.lastname: Gross
authors.affiliation: Department of Animal Sciences, University of Wisconsin, Madison 53706.
authors.forename: T D
authors.initials: TD
authors.lastname: Crenshaw
authors.affiliation: Veterinary Physiology, Vetsuisse Faculty, University of Bern, CH-3001 Bern, Switzerland.
authors.forename: R M
authors.initials: RM
authors.lastname: Bruckmaier
authors.affiliation: Department of Dairy Science, University of Wisconsin, Madison 53706. Electronic address: llhernandez@wisc.edu.
authors.forename: L L
authors.initials: LL
authors.lastname: Hernandez
mesh_terms: D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D002417:Cattle / Q000502:physiology*; D003126:Colostrum; D005260:Female; D008892:Milk; D049590:Postpartum Period / Q000502:physiology*; D011247:Pregnancy; D012701:Serotonin / Q000097:blood* / Q000378:metabolism; D013997:Time Factors
chemical_list: D012701:Serotonin
keywords: calcium; colostrum; precalving milking; serotonin