Evaluation ofBrassica carinatameal on ruminant metabolism and apparent total tract digestibility of nutrients in beef steers1,2

Abstract

Brassica carinata is a new oilseed crop with the potential of producing high-quality jet biofuel. A high-protein meal (~40% crude protein) is obtained as a byproduct of hexane-solvent oil extraction; however, limited research is available on the use of this meal as a protein supplement for beef cattle. A duplicated 4 × 4 Latin square design was used to determine the effects of supplementation with B. carinata meal on ruminal fermentation, digestibility, and blood metabolites in beef cattle consuming bahiagrass hay (Paspalum notatum Flüggé), compared with frequently used protein supplements. Eight Angus crossbred steers (473 ± 119 kg initial BW) were randomly allocated to 8 pens, over 4 periods of 28-d each. Within period, steers were assigned to 1 of 4 treatments: 1) 1.62 kg/d cottonseed meal (CSM); 2) 2.15 kg/d dry distillers grains plus solubles (DDGS); 3) 1.39 kg/d B. carinata meal pellets (BCM); or 4) 1.17 kg/d soybean meal (SBM), supplemented daily, on an isonitrogenous basis. Steers had ad libitum access to bahiagrass hay and water. Intake was measured using the GrowSafe system. Following a 14-d adaptation, feed and fecal samples were collected to determine apparent total tract nutrient digestibility using indigestible NDF as an internal marker. Blood and ruminal fluid samples were collected before providing the protein supplements and then every 3 h, during a 24-h period, to analyze urea nitrogen (PUN) and glucose in plasma, as well as ruminal pH, ammonia nitrogen (NH 3-N), and VFA concentrations. Data were analyzed using PROC MIXED of SAS with repeated measures. Model included the fixed effects of treatment, time, treatment × time, square, and period, and the random effects of steer(square) and steer(treatment). No effect of treatment (P > 0.05) was observed for pH, NH 3-N, or glucose concentration. An effect of treatment (P < 0.01) was observed for PUN, with steers receiving SBM having greater concentrations. A treatment × time interaction was observed (P < 0.05) for total VFA concentration, acetate to propionate ratio, and molar proportions of acetate, propionate, butyrate, and valerate. Steers consuming SBM had greater molar proportions of branchedchain VFA (P < 0.01) compared with CSM and DDGS. There was no effect of treatment (P > 0.05) on intake or apparent total tract digestibility of nutrients. Brassica carinata performed similarly to commonly used protein supplements indicating its viability as a protein supplement for beef cattle.

Feeding Canola, Camelina, and Carinata Meals to Ruminants

“…The Association of American Feed Control Officials (AAFCO) recommends that meals containing glucosinolates should not be fed at more than 10% DM [74]; therefore, the inclusion level of CRM follows the same restriction. Studies using CRM for dairy or beef cattle are still scarce, and to our knowledge there are only three published studies [68,78,79]. Rodriguez-Hernandez and Anderson [68] determined the effects of feeding CRM to dairy heifers on growth, ruminal fermentation, and nutrient utilization.…”

“…In an experiment carried out over two consecutive years [78], eight steers were used in a duplicated 4 × 4 Latin square and fed 1.39 kg/d of CRM (approximately 0.3% BW). Authors reported that there were no effects on DMI for steers fed CRM compared to steers fed either CSM, DDGS, or SBM.…”

“…The study of Schulmeister et al [78] was performed using solvent-extracted pellets of CRM. This meal contained 43.3% CP and 28 µmol/g glucosinolates.…”

“…However, they observed that feeding CRM increased the molar proportions of acetate and isovalerate. Interestingly, even though the study of Schulmeister et al [78] used solvent-extracted CRM (hexane), and Rodriguez-Hernandez et al [68] used cold-pressed CRM, both studies observed similar responses of ruminal fermentation.…”

“…Meanwhile, inclusion of CMM had no effects on plasma nonester fatty acids and glucose concentration [11,56,78]. However, infusion of CMM significantly increased the concentration of PUFA (C18:2 and C18:3) and decreased the concentration of saturated and monounsaturated fatty acids in the plasma of dairy cows (C16:1 and C18:1; 30), and increased the circulating concentration of PUFA in beef cattle when 2 kg DM/d of CMM was fed [65], which could be due to the increase of PUFA in the diets supplemented with CMM.…”