Nutrient concentrations and profile of non-structural carbohydrates vary among different Brassica forages

Abstract

Context Brassica forages are used in times of seasonal shortage to fulfil nutritional requirements of beef cattle, dairy cows, sheep or pigs. Although brassicas have been reported with high concentrations of readily fermentable carbohydrate, details have not been fully described and there is little information about the non-structural carbohydrate (NSC) profiles of Brassica forages. Aim The study was designed to evaluate nutrient concentrations, as well as NSC levels and constituents, of the main Brassica forages and to determine differences among varieties. Methods Five varieties of each of the four main forage brassicas (summer turnip, forage rape, kale and swede) were grown in plots and harvested for chemical analysis of the nutrient concentrations and NSC profiles of leaf and bulb (turnip and swede) and leaf and stem (rape and kale) components. Key results Brassica species differed in the amounts and types of NSC; swede had the highest concentration of NSC, mainly comprising sugars (glucose and fructose), followed by kale (with similar proportions of glucose, sucrose and fructose), turnip (with similar concentrations of glucose and starch and slightly lower fructose), and forage rape (in which starch was the main NSC). Forage chemical composition and NSC profile of plant organs varied among varieties of individual Brassica forages; for example, there were significant differences among swede varieties for concentrations of starch and sugar (total and profile) in bulbs. Conclusions Brassica forages differed with respect to quantities and types of NSC; swede had higher concentrations, mainly composed of glucose and fructose, followed by kale with similar proportions of glucose, sucrose and fructose, and turnip with NSC represented by glucose, starch and slightly lower fructose; and finally, forage rape, in which starch was the main NSC. Chemical composition, as well as NSC profile of plant organs (leaves, bulbs or stems), varied among varieties of Brassica species. Implications The approach described here has implications for ration formulation and is useful when considering the nutritional and dietary requirements of the animals of interest, because the type of Brassica, the variety and the proportion of plant organs can affect animal performance.

Acceptability, Preferences, and Palatability of Diets Containing Summer and Winter Brassica Forage in Growing Pigs: A Pilot Study

“…Wheat middlings had more NDF content (34.97%) compared to bulb turnip (17.9%) and forage rape meals (18.6%), more starch (21.8%, 11.1%, and 15.9%, for wheat middlings, bulb turnip and forage rape meals, respectively) and less sugars (0%, 20.8%, and 14.6% for wheat middlings, bulb turnip, and forage rape meals, respectively). In experiment 2, wheat middlings (34.97%) and kale meal (33.4%) had considerably more NDF content compared to bulb swede meal (14.7%), whereas sugar content among is greater for bulb swede meal (37.0% of sugars, with 20.7% glucose and 14.6% fructose), followed by kale meal (16.1% of sugars, with 7.8% sucrose, 4.3% glucose, and 3.4% fructose) and wheat middlings without sugar concentration [ 11 , 26 ]. We expected to find differences in acceptability or preference among diets since pigs show a marked attraction for sweet ingredients [ 38 ] and thus, an increased consumption in short tests.…”

“…Regarding the preference test, the diet with 15% of swede bulb was preferred over the diets with wheat middlings and kale. Swede have a greater concentration of glucose and fructose as compared to kale [ 11 ]. The sugar content may affect preferences creating a higher hedonic reaction in rats and pigs [ 23 , 28 ].…”

“…napobrassica ) [ 8 ]. The chemical composition of brassicas varies due to the leaf/bulb-stem ratio [ 10 , 11 ]. The crude protein (CP) content of leaves can range from 15–25% on a DM basis, whereas the bulb (root) of turnips and swedes varies from 9% to 16% of the DM [ 7 , 12 ].…”

“…In terms of sugar content (raffinose, sucrose, glucose, fructose), swede bulbs are higher (32%) followed by turnip bulbs (21%), whole plant kale (18%), and rape (14%). Whereas starch content varies 6–11% in forage rape, 1–2% in kale leaves, 1–3% in swede bulbs, and 7.6–16.5% in turnip bulbs [ 11 ]. In general, brassica crops have a high fiber (soluble and insoluble) content.…”

“…In general, brassica crops have a high fiber (soluble and insoluble) content. The insoluble fiber (IF in terms of NDF) ranges from 16.5% to 19.6% in swedes, 18% to 24% for turnip and rape, and 27.1% to 32.8% for kale; whereas soluble fiber (SF) ranges from 24% to 38% [ 11 ]. The SF is mainly composed of pectins (7–9%), galactans and β-glucans, among others [ 7 , 8 , 12 , 13 ].…”