title: Effects of body weight loss on serum progesterone concentrations of non-lactating dairy cows.
abstract: The objective was to evaluate serum concentrations of nonesterified fatty acids (NEFA), cortisol, insulin, and progesterone (P4) of dairy cows maintaining or mobilizing body weight (BW). Eleven non-lactating, non-pregnant, and ovariectomized Gir × Holstein cows were stratified by BW and body condition score (BCS), and randomly assigned to: 1) BW loss (six cows; LOSS) and 2) BW maintenance (five cows; MAINT). Treatments were achieved through a grazing schedule using three pastures. From Days -7 to 1 of the study, all cows were maintained in Pasture A (12 kg of dry matter/cow daily). From Days 2 to 30, LOSS cows were maintained in Pasture B (less than 1.0 kg of dry matter/cow daily), whereas MAINT cows were maintained in Pasture C (12 kg of dry matter/cow daily). However, from Days 3 to 30 of the study, cows from both treatments were regrouped daily into Pasture A from 0600 to 1200 h to allow LOSS cows to consume, on average, 4.5 kg/d of forage dry matter. On Day -66 of the study, all cows received an intravaginal drug releasing device containing 1.9 g of P4 (replaced every 14 d and removed on Day 3). Cow BW and BCS were assessed on Day 0 and 30 and blood samples were collected daily from Days 0 to 30 at 0600 and 1200 h. Changes in BW and BCS were greater (P ≤ 0.05) in LOSS cows compared to MAINT cows. Within samples collected at 0600 h, serum NEFA concentrations were often greater (P < 0.05) in LOSS cows compared to MAINT after Day 14. Serum P4 concentrations were greater (P < 0.05) on Days 21 and 22, and tended (P < 0.10) to be greater on Days 16, 23, and 24 of the study in LOSS cows compared to MAINT. In conclusion, BW loss was associated with increased circulating concentrations of P4 in non-lactating ovariectomized dairy cows; this was mainly attributed to fat mobilization and consequent release of P4 stored in adipose tissues.
authors.affiliation: São Paulo State University, Department of Animal Production, Botucatu, Brazil.
authors.forename: R O
authors.initials: RO
authors.lastname: Rodrigues
authors.forename: C
authors.initials: C
authors.lastname: Trevisanuto
authors.forename: R F
authors.initials: RF
authors.lastname: Cooke
authors.forename: J L M
authors.initials: JL
authors.lastname: Vasconcelos
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D002417:Cattle / Q000097:blood*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006854:Hydrocortisone / Q000097:blood; D007328:Insulin / Q000097:blood; D011374:Progesterone / Q000097:blood* / Q000494:pharmacology; D015431:Weight Loss
chemical_list: D005230:Fatty Acids, Nonesterified; D007328:Insulin; D011374:Progesterone; D006854:Hydrocortisone