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 FAs), which have been shown to impact reproductive performance. This study aimed to determine the effects of a flaxseed oil-based supplement (FLAX) 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 (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 a FLAX (n = 30) for 8 wk. Heifers were individually fed by an automated feeding system with a basal diet (total mixed ration, TMR), a mix of corn silage, grass hay, and dried distillers grains plus solubles (DDGS) offered ad libitum. Water and supplements were provided in separate feeders to measure intake and were compiled over 24 h for each animal by the Insentec system. In 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 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/artificial insemination (AI); % (n)] was performed at ∼30 d and ∼60 d 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 and linoleic acids were greater in FLAX (P < 0.03). In addition, eicosapentaenoic, arachidonic, and total polyunsaturated fatty acids tended to be greater for heifers in the FLAX group (P > 0.07). In conclusion, supplementation of n-3 FAs 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.