The effects of feeding high-linoleic safflower seeds on estrus synchronization in beef heifers
Spence, Kaitlyn Claire.
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The objectives of these studies were to investigate the effects of feeding high-linoleic cracked safflower seeds on reproductive and performance outcomes in pubertal beef heifers. Three experiments were conducted at Montana State University research facilities (Exp. 1, n = 48, BW = 370 ± 24.8 kg; Exp. 2, n = 40, BW = 396.5 ± 31.7 kg; Exp. 3, n = 63, BW = 404.4 ± 26.14 kg). Angus and Angus crossbred heifers were stratified by BW and allocated randomly to the following experimental treatments; 1) fed 1.8 kg/d barley grain concentrate (Barley); or, 2) fed 1.8 kg/d of high linoleic cracked safflower seed (Safflower). Heifers were fed 35 and 29 d, Exp. 1, Exp. 2 and 3. Following the feeding period, heifers (Exp. 1 and 2) were artificially inseminated (AI) 12 h after the onset of estrus, and heifers that did not show estrus were administered 25 mg of PGF 2 alpha and time AI. A 7-d CO-synch + CIDR and TAI protocol was used for heifers in Exp. 3. Performance variables included initial and final BW, live wt gain, ADG, and DMI (Exp. 1 and 2). Biweekly blood samples were assayed for progesterone (P4) and PGF 2 alpha metabolites (PGFM) concentrations (Exp. 1). Estrus responses were observed using Estrotect tags, heifers with progesterone (P4) < 1 ng/mL were not included in the calculation. Pregnancy rates were determined 40 d post breeding. Performance variables did not differ between barley and safflower treatments with the exception of DMI in Exp. 2. Heifers supplemented with barley consumed 21% more (P < 0.001) DM per d than heifer fed safflower. In Exp. 1, overall pregnancy rates were greater in safflower supplemented heifers than in barley supplemented heifers (P = 0.036). Pooled PGFM concentrations differed by day (P < 0.05) in Exp. 1. Results suggest supplemental high linoleic safflower seed does not appear to influence estrus response or PGFM concentrations in pubertal beef heifers.