title: Effects of rumen-protected polyunsaturated fatty acid supplementation on reproductive performance of Bos indicus beef cows.
abstract: Five experiments evaluated the effects of rumen-protected PUFA supplementation on reproductive function of Bos indicus beef cows. In Exp. 1, 910 lactating primiparous Nelore cows were randomly assigned to receive 0.4 kg/d of a protein-mineral mix in addition to 0.1 kg/d of a rumen-inert PUFA source (PF) or 0.1 kg/d of kaolin (rumen-inert indigestible substance; control), from the beginning of estrus synchronization protocol (d -11) until 28 d after fixed-time AI (TAI; d 28). Cows supplemented with PF had greater (P = 0.04) pregnancy rates compared with control cows (51.2 vs. 39.6%). In Exp. 2, 818 lactating primiparous Nelore cows were assigned to the same TAI schedule from Exp. 1 and randomly allocated to receive 1) control from d -11 to 28, 2) PF from d -11 to 16 and control from d 17 to 28, or 3) PF from d -11 to 28. Cows receiving PF until d 28 had greater (P = 0.02) pregnancy rates compared with control cows and tended to have greater (P = 0.10) pregnancy rates compared with cows receiving PF until d 16 (42.9, 31.3, and 35.8%, respectively). In Exp. 3, 435 nulliparous and multiparous lactating B. indicus-crossbred cows were randomly assigned to receive control or PF from the end of synchronization protocol (d 0) until 21 d after fixed-time embryo transfer (d 28). Cows supplemented with PF had greater (P = 0.07) pregnancy rates compared with control cows (49.6 vs. 37.7%). In Exp. 4, 504 lactating multiparous Nelore cows were randomly assigned to receive PF or a similar supplement containing a rumen-protected SFA source (SF) for 28 d beginning after TAI. Cows supplemented with PF had greater (P = 0.02) pregnancy rates compared with SF cows (47.9 vs. 35.5%). In Exp. 5, 9 nonlactating, nonpregnant, ovariectomized Gir x Holstein cows inserted with an intravaginal progesterone (P4)-releasing device were stratified by BW and BCS and divided into 3 squares. Squares were randomly assigned to receive control, PF, or a protein-mineral mix containing 0.2 kg/d of rumen-inert PUFA source (PF2), in a Latin square 3 x 3 design containing 3 periods of 14 d each. Cows supplemented with PF had greater (P = 0.03) mean serum P4 concentrations compared with control and PF2 cows (1.81, 1.66, and 1.68 ng/mL, respectively). These results indicate that supplementing 0.1 kg/d of rumen-inert PUFA to beef cows, particularly after breeding, may be a method of enhancing their reproductive performance, perhaps by increasing circulating P4 concentrations.
authors.affiliation: Departamento de Produção Animal, Faculdade de Medicina Veterinária e Zootecnia-UNESP, Botucatu-SP 18618-000, Brazil.
authors.forename: C N
authors.initials: CN
authors.lastname: Lopes
authors.forename: A B
authors.initials: AB
authors.lastname: Scarpa
authors.forename: B I
authors.initials: BI
authors.lastname: Cappellozza
authors.forename: R F
authors.initials: RF
authors.lastname: Cooke
authors.forename: J L M
authors.initials: JL
authors.lastname: Vasconcelos
mesh_terms: D000282:Administration, Intravaginal; D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000502:physiology*; D019587:Dietary Supplements; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D005260:Female; D011247:Pregnancy; D018873:Pregnancy Rate; D011270:Pregnancy, Animal / Q000187:drug effects* / Q000502:physiology; D011374:Progesterone / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology; D011897:Random Allocation; D012417:Rumen / Q000502:physiology
chemical_list: D005231:Fatty Acids, Unsaturated; D011374:Progesterone