title: Effects of rumen-protected choline supplementation on metabolic and performance responses of transition dairy cows.
abstract: The objective of this experiment was to compare metabolic and milk production parameters in dairy cows supplemented and nonsupplemented with rumen-protected choline (RPC) during the transition period. Twenty-three nonlactating, multiparous, pregnant Holstein cows were ranked by BW and BCS 21 d before expected date of calving and immediately were assigned to receive (n = 12) or not receive (control; n = 11) RPC until 45 d in milk (DIM). Cows supplemented with RPC received (as-fed basis) 50 and 100 g/d of RPC (18.8% choline) before and after calving, respectively. Before calving, cows were maintained in 2 drylot pens according to treatment with ad libitum access to corn silage, and individually they received (as-fed basis) 3 kg/cow daily of a concentrate. Upon calving, cows were moved to 2 adjacent drylot pens according to treatment, milked twice daily, offered (as-fed basis) 35 kg/cow daily of corn silage, and individually received a concentrate formulated to meet their nutritional requirements after milking. The RPC was individually offered to cows as a topdressing into the morning concentrate feeding. Before calving, cow BW and BCS were recorded weekly, and blood samples were collected every 5 d beginning on d -21 relative to expected calving date. Upon calving and until 45 DIM, BW and BCS were recorded weekly, individual milk production was recorded daily, and milk samples were collected once a week and analyzed for fat, protein, and total solids. Blood samples were collected every other day from 0 to 20 DIM and every 5 d from 20 to 45 DIM. Based on actual calving dates, cows receiving RPC or control began receiving treatments 16.8 ± 1.7 and 17.3 ± 2.0 d before calving, respectively. No treatment effects were detected (P ≥ 0.18) on postpartum concentrate intake, BW and BCS, or serum concentrations of cortisol, β-hydroxybutyrate, NEFA, glucose, and IGF-I. Cows supplemented with RPC had greater (P ≤ 0.01) mean serum haptoglobin and insulin concentrations compared with control. Cows supplemented with RPC had greater (P < 0.01) milk protein, total solids (P < 0.01), and milk fat concentrations (P = 0.09) compared with control. No treatment effects were detected (P ≥ 0.43) for milk yield parameters, such as fat-corrected or solids-corrected milk yield. In conclusion, supplementing RPC to transition dairy cows increased haptoglobin and insulin concentrations and benefited milk composition.
authors.forename: T
authors.initials: T
authors.lastname: Leiva
authors.forename: R F
authors.initials: RF
authors.lastname: Cooke
authors.forename: A P
authors.initials: AP
authors.lastname: Brandão
authors.forename: R S
authors.initials: RS
authors.lastname: Marques
authors.forename: J L M
authors.initials: JL
authors.lastname: Vasconcelos
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000821:Animal Feed; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002417:Cattle / Q000378:metabolism*; D002794:Choline / Q000494:pharmacology*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D005260:Female; D006242:Haptoglobins / Q000378:metabolism*; D007328:Insulin / Q000097:blood*; D007774:Lactation / Q000187:drug effects* / Q000378:metabolism; D008892:Milk / Q000187:drug effects* / Q000378:metabolism; D008894:Milk Proteins / Q000187:drug effects / Q000378:metabolism; D049590:Postpartum Period; D011247:Pregnancy; D012417:Rumen / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors; D014886:Weaning
chemical_list: D001786:Blood Glucose; D006242:Haptoglobins; D007328:Insulin; D008894:Milk Proteins; D002794:Choline; D020155:3-Hydroxybutyric Acid