Feeding Value Assessment of Substituting Cassava (Manihot esculenta) Residue for Concentrate of Dairy Cows Using an In Vitro Gas Test

Abstract

The feeding value of replacing concentrate with cassava (Manihot esculenta) residue in the feed of Holstein cows was confirmed using an in vitro gas test. The treatments consisted of 0% (control, CON), 5%, 10%, 15%, 20%, 25%, and 30% inclusion of cassava residue in fermentation culture medium composed of buffer solution (50 mL) and filtrated rumen fluid (25 mL). The parameters analyzed included the kinetics of gas production and fermentation indexes. Forty-eight hours later, there were no significant differences on in vitro dry matter disappearance (IVDMD), pH, and microbial crude protein (MCP) content among treatments (p > 0.05). However, the “cumulative gas production at 48 h” (GP48), the “asymptotic gas production” (A), and the “maximum gas production rate” (RmaxG) all increased linearly or quadratically (p < 0.01). The GP48 was significantly higher in the 25% treatment compared to the other treatments, except for the 30% (p < 0.01). The A was significantly larger in the 25% treatment compared to the other treatments, except for the 20% and 30% (p < 0.01). The RmaxG was distinctly larger in the 25% treatment compared to other treatments (p < 0.01); moreover, the “time at which RmaxG is reached” (TRmaxG) and the “time at which the maximum rate of substrate degradation is reached” (TRmaxS) were significantly higher in the 25% treatment than the CON, 20%, and 30% treatments (p < 0.01). Additionally, the content of ammonia-N (NH3-N) in all treatments showed linearly and quadratically decreases (p < 0.01), whereas total volatile fatty acid (VFA), iso-butyrate, butyrate, and iso-valerate contents changed quadratically (p = 0.02, p = 0.05, p = 0.01, and p = 0.02, respectively); all of these values peaked in the 25% treatment. In summary, the 25% treatment was associated with more in vitro gas and VFA production, indicating that this cassava residue inclusion level may be used to replace concentrate in the feed of Holstein cows. However, these results need to be verified in vivo.

Diets Partially Replaced With Cassava Residue Modulate Antioxidant Capacity, Lipid Metabolism, and Gut Barrier Function of Huanjiang Mini-Pigs

“…Cassava ( Manihot esculenta ) is widely grown in tropical and subtropical regions. The world-wide production of cassava is estimated to be 276.7 million tons, and it provides valuable food sources for more than 105 developing countries ( 5 , 6 ). Cassava is still widely used in the production of starch, bioethanol, and other bio-products, such as feed, medicines, and biopolymers ( 5 ).…”

Hydroxy-selenomethionine supplementation promotes the in vitro rumen fermentation of dairy cows by altering the relative abundance of rumen microorganisms

“…In vitro dry matter disappearance (IVDMD) and gas production were calculated by Equation (; Zheng et al, 2021) and Equation (2) (Groot et al, 1996); the time corresponding to the maximum rate of substrate degradation (TRmaxS, h), the maximum rate of substrate digestion ( R maxS, h), the time corresponding to R maxG (TRmaxG, h), and the maximum gas production rate ( R maxG, ml/h) were calculated by Equations (–6), respectively (Yang et al, 2005). where ‘GP t ’ is the cumulative gas production (ml g −1 DM) at incubation time ‘ t ’ (h), ‘ A ’ is the asymptotic gas production (ml g −1 DM), ‘ B ’ is a sharpness parameter determining the shape of the curve, ‘ C ’ is the time (h) at which half of ‘ A ’ is reached and ‘ t ’ is the in vitro incubation time.…”

“…Next, 500 mg of the substrate was added into glass bottles, and buffer solution (50 ml) and rumen fluid (25 ml) were preheated to 39°C and placed into fermentation bottles. Bottles connected to the AGRS‐III system were cultured for 48 h at 39°C to record cumulative gas production, and the other bottles were incubated for 3, 6, 12 and 24 h in a thermotank at 39°C (Zheng et al, 2021 ). To ensure the consistency of rumen fluid, the substrates and buffer were added into the bottle first.…”

“…The content of VFA was detected through gas chromatography (Erwin et al, 1961 ) using a gas chromatography (TP‐2060, R.F.TianPu). The detailed operation of NH 3 ‐N, MCP, VFA and pH determination was followed (Zheng et al, 2021 ). The content of methane was analysed using the gas chromatographic method (Yang et al, 2014 ).…”

“…In vitro dry matter disappearance (IVDMD) and gas production were calculated by Equation (1; Zheng et al, 2021) and Equation (2) (Groot et al, 1996); the time corresponding to the maximum rate of substrate degradation (TRmaxS, h), the maximum rate of substrate digestion (RmaxS, h), the time corresponding to RmaxG (TRmaxG, h), and the maximum gas production rate (RmaxG, ml/h) were calculated by Equations (3-6), respectively (Yang et al, 2005).…”