In vitro fermentation and in situ rumen degradation kinetics of summer forage brassica plants

Abstract

The aim of the present study was to assess and compare the nutrient concentration, the in vitro fermentation and the in situ rumen degradation characteristics of Brassica rapa ssp. rapa L. (turnips) and Brassica napus ssp. biennis L. (forage rape). Five varieties of each species were established in three field replicates and were organised in a randomised complete-block nested design. All varieties were harvested and further analysed for chemical composition, in vitro gas-production kinetics, volatile fatty acid (VFA) production and in situ degradation kinetics of dry matter (DM) and crude protein. Turnips showed higher ash, total sugars, raffinose, sucrose, glucose and fructose concentrations (P < 0.001) than did forage rape. Turnip varieties differed in their sucrose, glucose, fructose and total soluble sugar concentration (P < 0.001), whereas rape varieties differed in their neutral detergent fibre concentration (P = 0.004) and digestible organic matter on a DM basis (P < 0.01). Regarding DM-degradation parameters, turnips had a higher soluble fraction ‘a’ (P < 0.01) and a lower insoluble, but potentially degradable fraction ‘b’ (P < 0.01) than did rape, but the fractional degradation rate ‘c’ (0.18/h) was similar to that of rape. Rates of gas production were slightly higher (P = 0.018) for turnip than for rape. No effects for brassica species nor for varieties within species were detected (P > 0.05) for total in vitro VFA production, as well as for the relative proportions of acetate, propionate, butyrate, branch chained VFA and the actetate:propionate ratio. Our study showed that most of the differences that were observed in terms of chemical composition and degradation kinetics did not result in differences in in vitro fermentation products.

Milk production responses and rumen fermentation of dairy cows supplemented with summer brassicas

“…As rumen bacteria use NH 3 nitrogen and branched chain SCFAs for their growth, therefore lowering NH 3 N and branched chain SCFAs concentrations which is comparable to our study with greater MN (Roman- Garcia et al, 2016). The greater MN when supplementing FR may be due to better energy supply in the rumen because of its high DM degradation rate (Keim et al, 2019) or due to changes in microbial communities. For example, Sun et al (2015) reported that feeding FR to lambs modified bacterial communities in the rumen compared to ryegrass-fed animals.…”

“…Summer turnips and FR diets contained a greater concentration of NFC compared to the control diet. According to Keim et al (2019), Barkant ST contains 82 g/kg of starch compared to 59 g/kg of starch in Spitfire FR (the cultivars used in this study) and more water soluble carbohydrates (144 v. 131 g/kg DM; specifically sucrose, glucose and fructose). These differences in type and quantity of NFC are expected to modulate rumen fermentation (Oba, 2011) and might be responsible for the greater tSCFA and butyrate in the rumen of cows (6 h after supplementation) supplemented with ST.…”

“…Generally, ST has greater metabolizable energy (ME) contents than FR (3.0 and 2.8 Mcal/kg DM, respectively), while CP content is greater in FR (160 to 200 g/kg DM) than in ST (110 to 140 g/kg DM, respectively) (Westwood and Mulcock, 2012;Barry, 2013). Recently, Keim et al (2019) concluded that most of the differences that were observed in terms of chemical composition and degradation kinetics between ST and FR did not affect in vitro fermentation products. However, extrapolations of in vitro results to in vivo situations must be done carefully (Yanez-Ruiz et al, 2016).…”

Rumen In Vitro Fermentation and In Situ Degradation Kinetics of Winter Forage Brassicas Crops

“…Whereas degradation kinetics and ruminal fermentation of summer brassica species (rape and turnip) and varieties [16] have been reported in the literature, few reports exist on the effect of winter brassica species (kales and swedes) and varieties on the in situ degradation kinetics and fermentation end products. For example, Sun et al [4] have observed that sheep fed swedes showed modified VFA profiles in their rumen fluid and lowered methane yield in contrast with those fed kales or perennial ryegrass.…”

“…Valderrama and Anrique [17] have reported DM and crude protein (CP) degradation kinetics of kale leaves; however, to the best of our knowledge, such data have not been reported for swedes. Moreover, the nutritive value of brassicas varies among species and varieties within species [3,16], and, therefore, information is still lacking about rumen fermentation and the kinetics of winter brassica species such as kales and swedes.…”