title: Lower pregnancy losses in lactating dairy cows fed a diet enriched in alpha-linolenic acid.
abstract: The objectives were to determine if a diet enriched in alpha-linolenic acid (ALA) would influence ovarian function, early embryo survival, conception rates, and pregnancy losses in lactating dairy cows. Beginning 28 d before breeding, Holstein cows (55 +/- 22 d postpartum; mean +/- SD) were assigned to diets supplemented with either rolled flaxseed (FLAX; 56.7% ALA, n = 62) or rolled sunflower seed (SUNF; 0.1% ALA, n = 59) to provide approximately 750 g of oil/d. Diets continued for 32 d after timed artificial insemination (TAI, d 0) following a Presynch/Ovsynch protocol. Barley silage- and barley grain-based TMR were formulated to meet or exceed National Research Council requirements. Metabolizable protein and net energy for lactation concentrations were similar in the 2 diets. Based upon a mean dry matter intake of 22 kg/d, cows fed FLAX or SUNF consumed > 410 g or < 1 g of ALA, respectively. Pregnancy was confirmed by ultrasound 32 d after TAI. Nonpregnant cows were placed on a second Ovsynch regimen and reinseminated 42 d after first TAI, and received oilseeds for 32 d after second TAI. Relative to prediet levels, FLAX increased the ALA content of milk by 187%. Ovarian ultrasonography was performed in 8 cows per diet; the mean diameter of ovulatory follicles was larger in cows fed FLAX compared with SUNF (16.9 +/- 0.9 vs. 14.1 +/- 0.9 mm), but follicle number, corpus luteum size, and plasma progesterone concentrations remained unaffected. Presumptive conception (progesterone < 1 ng/mL on d 0 and > 1 ng/mL on d 21) rates to first TAI were greater in FLAX than in SUNF (72.6 vs. 47.5%). Pregnancy losses were lower in cows fed FLAX (9.8%) compared with those fed SUNF (27.3%). Including flaxseed in the ration of dairy cows increased the size of the ovulatory follicle and reduced pregnancy losses.
authors.affiliation: Dairy Research and Technology Centre, Alberta Agriculture Food and Rural Development/University of Alberta, Edmonton T6H 5T6, Canada. divakar.ambrose@gov.ab.ca
authors.forename: D J
authors.initials: DJ
authors.lastname: Ambrose
authors.forename: J P
authors.initials: JP
authors.lastname: Kastelic
authors.forename: R
authors.initials: R
authors.lastname: Corbett
authors.forename: P A
authors.initials: PA
authors.lastname: Pitney
authors.forename: H V
authors.initials: HV
authors.lastname: Petit
authors.forename: J A
authors.initials: JA
authors.lastname: Small
authors.forename: P
authors.initials: P
authors.lastname: Zalkovic
mesh_terms: D000034:Abortion, Veterinary / Q000517:prevention & control*; D000821:Animal Feed / Q000032:analysis; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D002417:Cattle; D002418:Cattle Diseases / Q000517:prevention & control*; D002784:Cholesterol / Q000097:blood; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D019597:Flax; D006368:Helianthus; D001467:Hordeum; D007774:Lactation; D008892:Milk / Q000737:chemistry; D006080:Ovarian Follicle / Q000000981:diagnostic imaging; D010053:Ovary / Q000000981:diagnostic imaging; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D012639:Seeds; D012820:Silage; D014280:Triglycerides / Q000097:blood; D014463:Ultrasonography; D017962:alpha-Linolenic Acid / Q000008:administration & dosage* / Q000032:analysis
chemical_list: D001786:Blood Glucose; D004044:Dietary Proteins; D005230:Fatty Acids, Nonesterified; D014280:Triglycerides; D017962:alpha-Linolenic Acid; D011374:Progesterone; D002784:Cholesterol