Nutrition evaluation of an unconventional for ruminants estimated by the in vitro fermentation system

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Int. J. Biosci. 2016 Introduction In recent years, since the competition for grain between people and livestock, China ruminant industries are faced with the problems of meeting the nutritional requirement of the animals, lack of feed grain is one of the main choke points in livestock production (Liu and Wang, 2008). For sustainable intensification of ruminant industries, it is imperative to explore the potential of unconventional feedstuff resources. This is of economic and environmental benefits leading to a reduction in the cost of diets and consequently to a reduction in the production cost. Chinese herbs as the traditional medicine have been widely used in East Asian countries, and has experienced a history of thousands of years (Liang et al., 2013). It has been well-known that Chinese medicine residues are of interest due to high nutrient, low cost and availability in large quantities (Li et al., 2010). They are considered to be the major sources of nutrients for ruminant. However, very little is known about their nutrition evaluation. The nutritive value of a ruminant feed is determined by the concentrations of its chemical components, as well as their rates and extent of digestion (Getachew et al., 2004). Determining the digestibility of feeds in vivo is laborious, expensive, requires large quantities of feed, and is largely unsuitable for single feedstuff thereby making it unsuitable for routine feed evaluation (Coelho et al., 1998). In vitro method of feed evaluation is less expensive, less time consuming and more rapid alternative (Getachew et al., 2004; Akinfemi et al., 2009). Usually, the use of in vitro fermentation methodology to estimate the ruminant feed is based on the gas production, and in combination with the feed’s chemical composition (Menke and Steingass, 1988). This present study was conducted to investigate Chinese medicine residue for assessment as potential sustainable feed for ruminants by comparing with some commonly used roughage forages using chemical analysis and in vitro rumen fermentation methods. Materials and methods Sample collection Dried samples of commonly used forages (peanut vines, Chinese sedge, rice straw) were collected from the San Wang animal husbandry company, Le ping, Jiangxi, China. And the Chinese medicine residue was collected from a company in Nanchang, Jiangxi, China. All the samples were mill through a 1 mm screen and oven-treated at 65°C until a constant weight was obtained for dry matter determination. Chemical analyses Samples of peanut vines, Chinese sedge, rice straw and Chinese medicine residue were analysed for proximate analysis. Dry matter (DM) was determined at 105 °C for 24 h (Horwitz, 2000). Crude protein (CP) was determined according to Kjeldahl method using 2400 Kjeltec analyser unit (Foss tecator) and the crude fat (EE) content was determined by the ether extraction method according to AOAC (1990) (Horwitz, 2000). Crude fiber (CF), the neutral detergent fibre (NDF) and acid detergent fibre (ADF) was analysed according to Van Soest et al. (1991). Chemical analyses were performed in triplicate. In vitro incubation with sheep ruminal fluid Five sheep, maintained on a basal diet, were used to provide rumen contents. After a adaptation period, approximately 500 ml of rumen contents was collected from each sheep using a rumen fluid sampling pump on the same day before the morning meal. The rumen liquid was immediately mixed with CO2 to avoid O2 contamination and transferred to the laboratory in a thermostatic box (39°C) under anaerobic conditions. The rumen liquid was then filtered through four layers of cheesecloth into a flask under a continuous flow of CO2. An aliquot of the rumen liquid was buffered (1:3, v/v) by adding an artificial saliva solution (McDougall, 1948). Feeds (0.4 g of DM) were incubated in triplicate with 40 ml of inoculum. Gas production was measured over the range of 0-48 h of incubation at 6 h intervals. At the end of incubation period (48 h), pH, methane (CH4), volatile fatty acid (VFA), ammonia-N (NH3-N) and microbial protein production (MCP) contents were measured. 28 Sheng et al.
Int. J. Biosci. 2016 Effects on fermentation parameters Fermented medium pH was determined with a multiparameter pH meter (Sartorius PB-10, Sartorius, Gottingen, Germany). At the end of incubation (48 h), 1 ml of the fermented medium was collected in Eppendorf tubes containing 0.20 ml of 25 % metaphosphoric acid. The mixture was allowed to stand for 2 h at room temperature and centrifuged at 5,000×g for 10 min. The analysis of VFA was conducted according to the method described by Agarwal et al. ( 2009). The ammonia-N was analysed in the fermented medium as per the procedure described by Wheatherburn (1967). Concentrations of the MCP were determined based on purines using the method of Zinn and Owens (1986), modified by Makkar and Becker (1997), and estimated from the ratio of purines to N of isolated bacteria with yeast RNA as standard. Statistical analysis Data on chemical composition and fermentation parameters were analyzed using the one-way analysis of variance (ANOVA) procedure with SPSS 16.0. Multiple comparison tests used Duncan’s multiplerange test (Snedecor and Cochran, 1980). The correlations between chemical constituents and fermentation products were established by calculating Pearson’s correlation coefficient using SPSS 16.0. Results Chemical composition Chemical compositions of peanut vines, Chinese sedge, rice straw and Chinese medicine residue were shown in Table 1. There were observed variations in the chemical composition of the different fermentation substrates, with DM ranging from 26.00 % to 91.77 %, CP from 6.20 % to 13.50 %, EE from 1.00 % to 7.26 %, CF from 18.95 % to 29.60 %, NDF from 33.03 % to 67.50 %, and ADF from 24.33 % to 46.34 %. Among them, the Chinese medicine residue showed the highest CP (13.50 %) and EE (7.26 %), the lowest CF (18.95 %), NDF (33.03 %) and ADF (24.33 %) (Table 1), which indicated its good feeding value for ruminants in terms of feed intake and digestibility and might be another good forage for ruminant. Table 1. Chemical composition of fermentation substrates. Items Dry matter DM % Crude protein CP % Crude fat EE % Crude fiber CF % Neutral detergent fiber NDF % Acid detergent fiber ADF % Peanut vines 91.30 11.00 1.50 29.60 60.40 46.34 Chinese sedge 91.77 10.11 4.96 24.40 66.21 35.72 Rice straw 90.30 6.20 1.00 27.00 67.50 45.40 Chinese medicine residue 26.00 13.50 7.26 18.95 33.03 24.33 Effects on fermentation parameters In vitro gas production The fermentation gas accumulation curves displayed a nonlinear trend over the incubation period, the accumulated gas production reached asymptote around 24 h of incubation except rice straw group, gas production in rice straw group increased continuously over 48 h of incubation. Among these substrates, the fermentation gas accumulation rate and volume was greatest in Chinese medicine residue, followed by peanut vines and chinese sedge, the gas volume of rice straw was the least one, it was only 53.60 % of that from Chinese medicine residue at 24 h (Fig. 1). pH, NH3-N, and MCP The pH varied in different groups, but was still in the normal range throughout the incubation, ranging from 6.44 to 6.57 (Table 2). Among these groups, fermenters with Chinese medicine residue as substrate had a significant lower pH value than the other substrates (P
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Nutrition evaluation of an unconventional for ruminants estimated by the in vitro fermentation system

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