Omega-3 supplement alters water consumption and plasma fatty acid profile of beef heifers.

Flaxseed oil contains elevated levels of omega-3 fatty acids (n-3 FA), which have been shown to impact reproductive performance. This study aimed to determine the effects of a flaxseed oil-based supplement on reproductive parameters, feeding behavior, and lipid profile in beef heifers. Sixty Angus and Simmental × Angus heifers (14 months old ± 2 months), blocked by full body weight (BW; 396.79 ± 33.78 kg) ± SD and antral follicle count, were randomly assigned to one of two ad libitum supplementation treatments: a commercial loose mineral supplement (CON; n = 30) or flaxseed oil-based supplement (FLAX; n = 30) for 8 weeks. Heifers were individually fed by an automated feeding system where basal diet (TMR), a mix of corn silage, grass hay, and DDGS as offered ad libitum. Water and supplements were provided in separate feeders to measure intake and were compiled over 24 hours for each animal by the Insentec system. On week 5, heifers were enrolled in a fixed-time artificial insemination (FTAI) protocol. The presence of a corpus luteum (CL) was recorded weekly, as well as the largest follicle diameter (LFD) and CL presence on days of the FTAI protocol (D0, D7, and D9). Puberty attainment was determined when a CL could be visualized by ultrasound and/or the blood sample contained concentrations of P4 above the threshold level of 1 ng/mL. Pregnancy diagnosis [P/AI; % (n)] was performed at ∼30d and ∼60d following AI. Plasma samples were collected once weekly and on days 0, 7 and 9 of the FTAI protocol for circulating progesterone (P4), estradiol (E2), and fatty acid (FA) profiles. Water intake in kilograms per day (kg/d) was lower in FLAX while TMR intake (kg/d) tended (P = 0.08) to be greater in FLAX compared to CON. Additionally, puberty tended to be attained faster (P = 0.10), and P4 on D9 tended to be lower (P = 0.09) for FLAX heifers. Concentrations of α-linolenic (ALA), and linoleic (LA) acids was greater in FLAX (P < 0.03). In addition, eicosapentaenoic (EPA), arachidonic (AA), and total polyunsaturated fatty acids (PUFA) tended to be greater for heifers in the FLAX group (P > 0.07). In conclusion, supplementation of n-3 FA caused lower water intake, higher plasma FA, and a tendency for faster puberty attainment. In conjunction, these findings offer data to support the use of a flaxseed oil-based supplement as a positive supplementation strategy for beef heifers to induce an optimal endocrine environment and potentially anticipate puberty.