PSIX-24 The effects of camelina meal in western Canadian winter-feeding diets on feed intake and growth performance of replacement beef heifers.

Abstract This study aimed to evaluate the effects of camelina meal supplementation in western Canadian winter-feeding diets on dry matter intake (DMI) and growth performance of replacement beef heifers. One hundred and one crossbred replacement beef heifers were used in a completely randomized design and randomly assigned to one of four dietary treatments. The treatments assigned to each pen included; CON: the basal diet (60% grass hay, 15% barley straw, 10% corn silage, 10% barley grain, 5% supplement; dry matter (DM) basis, CANOLA: basal diet with canola meal replacing the 10% barley grain, MIX: basal diet with 5% canola meal and 5% camelina meal replacing 10% of the barley grain, and CAMELINA: basal diet with camelina meal replacing 10% of barley grain. The experiment consisted of a 28-d baseline measurement period where all pens received the CON diet, followed by two consecutive 42-d dietary feeding periods. Body weight was measured on two consecutive days at the beginning and end of the experiment and once at the beginning and end of each feeding period. Feed was provided ad libitum and feed intake was individually measured using the GrowSafe feed system. Cattle and their respective treatments were shuffled between pens once every week to ensure all cattle and all treatments were represented in each pen for every period. Statistical analysis was performed using the GLIMMIX procedure of SAS (SAS Institute Inc., Cary, NC, USA) with treatment as a fixed effect, and heifer as the experimental unit. During the first feeding period, CAMELINA cattle had lower (P < 0.01) dry matter intake (DMI) than all other treatments; however, there was no difference in average daily gain (ADG; P = 0.07) among treatments. The gain to feed ratio (GF) during the first feeding period was greater (P < 0.01) for CANOLA compared to MIX and CAMELINA, with CON being similar to all treatments. Body weight gain (BWG) was greatest for MIX and lowest for CANOLA (P = 0.05). In the second feeding period, treatment did not affect DMI (P = 0.25), while ADG was lower (P = 0.04) for CON compared to CANOLA. In the second period, GF was lower (P < 0.01) for CON than MIX, and BWG was greatest for CAMELINA and lowest for CON (P = 0.04). In conclusion, feeding camelina meal at 5% dietary DM into a high roughage diet improved GF, whilst feeding camelina at 10% DM initially reduced DMI but did not affect GF. These results suggest that camelina meal can replace canola meal in high roughage diets without adversely affecting growth performance.