Evaluation of Brassica Carinata Meal As a Protein Supplement for Growing Beef Heifers

Brassica carinata is a new oilseed crop in Florida with the potential of producing high-quality biodiesel for use as jet biofuel. A high-protein meal (~40% CP) is obtained as a byproduct of oil extraction, however, this meal has not been tested as a potential supplement for growing beef cattle. The objective of this experiment was to determine the effects of supplementation with Brassica carinata meal (BCM) on animal performance, attainment of puberty, and blood profile in growing beef heifers consuming bermudagrass hay (Cynodon dactylon). Sixty-four Angus crossbred heifers (240 ± 39 kg initial BW) were stratified and blocked (2 blocks: light and heavy) by initial BW and randomly allocated into 18 pens over 2 consecutive yr (10 pens in yr 1 and 8 pens in yr 2). Within block, pens were randomly assigned to one of two treatments: 0 (CTL) or 0.3% of BW/d (as fed) of BCM pellets. All heifers were provided ad libitum access to bermudagrass hay and water, and BCM pellets were supplemented daily in the pen. Body weight and blood samples were collected weekly for 70 d, before the daily supplementation. Plasma was analyzed for concentrations of progesterone, triiodothyronine (T3), and thyroxine (T4). Data were analyzed as a generalized randomized block design including the fixed effects of treatment, wk, treatment × wk, block, and block × treatment, and the random effect of year. Repeated measures, with pen within year as subject, were used to analyze T3 and T4 concentrations over time. A survival analysis was conducted to determine time to attainment of puberty. There was a difference (P ˂ 0.01) in ADG between CTL (0.14 kg) and BCM (0.42 kg). There was no treatment or block (P > 0.05) effect for concentrations of T3 and T4; however, there was a difference in wk (P < 0.01). Time to attainment of puberty did not differ between treatments (P = 0.68); however, there was an effect of block (P < 0.01) where the light block heifers attained puberty earlier compared to the heavy block heifers. Feeding B. carinata meal as a protein supplement at 0.3% of BW/d is a viable option for increasing ADG of growing beef heifers, without affecting the attainment of puberty.