In vitro fermentation and nutrients digestibility parameters of diets containing different levels of sugarcane bagasse

In vitro fermentation and nutrients digestibility parameters of diets containing different levels of sugarcane bagasse


Introduction: The high cost and scarcity of feed, and increasing demand for animal product such as meat and milk increased the need for efficient utilization of high lignocellulose roughages for ruminant production. Iran is one of the arid and semi-arid desert regions and is facing a shortage of crops and fodder. On the other hand, there is always the problem of providing cheap and acceptable quality feed for livestock, and one of the ways to solve this problem is to use unusual feed such as crop residues and food factories; But most of these foods have not been studied and their chemical composition and level of consumption for animals are not well known. This requires the study of the effect of different levels of food sources on the diet and the determination of animal production responses. Sugarcane bagasse can be used as a substitute for part of the diet forage (wheat straw) for animal feed due to its high cellulose content and high palatability. The aim of this study was to investigate the effect of diets containing different levels of old or fresh bagasse as a substitute for wheat straw in ewes's diet on chemical composition, fermentation parameters and digestibility of dry matter and organic matter by gas production method. The in vitro gas production system helps to better quantify nutrient utilization, and its accuracy in describing digestibility in animals has been validated in numerous experiments. Based on the strong relationship between measured digestibility and that predicted from gas production, regression equations have been developed and the method has been standardized.
Material and methods: A sample of bagasse was obtained from a sugarcane factory located in Khuzestan province and a sample of wheat straw was obtained from agricultural farms and immediately transferred to a nutrition laboratory. The old bagasse was stored in storage for a year. Experimental diets were adjusted based on the nutrient requirements of ewes (NRC, 2007) and included 50% forage (20% alfalfa and 30% straw) and 50% concentrate (32.5% barley, 10% soybean meal, 7% wheat bran and 0.5% of vitamin and mineral supplements were based on dry matter. The experimental treatments, old or fresh bagasse was replaced with wheat straw at different levels, so that the experimental diets in the first experiment (old bagasse) included: Diet 1: Diet containing 30% wheat straw, Diet 2: Diet containing 22.5% Wheat straw and 7.5% old bagasse, Diet 3: Diet containing 15% wheat straw and 15% old bagasse, Diet 4: Diet containing 7.5% wheat straw and 22.5% old bagasse and Diet 5: Diet containing 30 Percentage of old bagasse; And in the second experiment (fresh bagasse) including: diet 1: diet containing 30% wheat straw, diet 2: diet containing 22.5% wheat straw and 7.5% fresh bagasse, diet 3: diet containing 15% wheat straw and 15 Percentage of fresh bagasse, diet 4: diet containing 7.5% wheat straw and 22.5% fresh bagasse and diet 5: diet containing 30% fresh bagasse. The fresh bagasse sample was dried in an oven at 60 ° C for 48 hours and after determining the dry matter content, along with the old bagasse sample, wheat straw and experimental diets ground through a 1-mm screen using a Wiley mill, and analysed for dry matter (DM), organic matter (OM), crude protein (CP) (AOAC, 2019), neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) (Van Soest et al., 1991). For measurement of methane production, the final gas production (end of 24 hours) was recorded after 24 hours of incubation of the sample in ruminal fluid + phosphate buffer. Then 10 M sodium hydroxide was added to the contents of the glass bottle to absorb the carbon dioxide gas. After absorbing carbon dioxide (after about 10 minutes), the gas remaining in the syringe or glass bottle will be methane (Fievez et al., 2005). The chemical composition of the treatments statistically analyzed in a completely randomized design and gas production, separation factor, dry matter and organic matter digestibility, microbial mass production and production efficiency and methane production statistically analyzed in a randomized complete block design. Statistical analysis of data was performed using SAS (2006) software.
Results and discussion: The results showed that wheat straw compared to fresh or old bagasse had a higher content of DM, CP, ash, Total gas accumulation 24h (ml), digestibility of DM and OM and lower content of OM, NDF, ADF and ADL (P˂0/05). The ADL and NDF contents of fresh bagasse was lower than old bagasse (P˂0/05). Among the experimental diets, the highest content of DM and ash, and the lowest content of OM and ADF belonged to the diet containing 30 percent wheat straw (P˂0/05). Diets containing different levels of old or fresh bags had higher and lower NDF content, respectively, compared to the diet containing wheat straw (P˂0.05). The digestibility of DM and OM in the diet containing 30 percent of old and fresh bagasse tended to decrease compared to its lower levels (P = 0/08 and 0/07). In general, if the price of each kilogram of wheat straw is low compared to bagasse, it can be suggested that a maximum level of 22.5 percent of bagasse be used instead of wheat straw in the diet of ewes; Of course, the 30 percent bagasse level can also be used with caution. It is recommended to use fresh bagasse instead of old bagasse in the diet of ewes.