In vitro effect of heat processed flaxseed on ruminal fermentation and methane emission response Farzaneh Mohammadi1, Mohsen Danesh Mesgaran1, Alireza Vakili1, Mohammadreza Dehghani2 1Ferdowsi University of Mashhad, Mashhad, Iran, 2Zabol University, zabol, Iran E-mail: f_mohamady66@yahoo.com Take home message It has been demonstrated that physically processed flaxseed may alter rumen fermentation. Introduction Flaxseed is an annual or biannual plant that has been cultivated as a commercial plant in over thirty countries all over the world. It yields seeds that mature 30-60 days after flowering and are a rich source of both edible and non-edible oils (34 - 40% DM). The seeds have long been used in animal diets (Matheson, 1976). The objective of the current research was to investigate the effect of different heat processing including roasting, water boiling and oven drying of whole flaxseed on in vitro ruminal fermentation, digestibility parameters and methane emission using gas production technique. Material & methods Samples of the whole flaxseed were obtained from several local markets. Samples were composited and any external weeds and dust were removed manually. Physical heat processing including roasting, boiling and oven heating was applied. A sub-section of the samples were ground through a 2 mm screen using CyclotecTM milling machine (Foss.1093, Denmark). Whole flaxseed was roasted by indirect heating on fire using a pan as the container for 2, 4, 6, 8 and 10 min. Whole flaxseed was boiled for 0.5, 1, 2 and 4 h by indirect heating of a boiler containing flaxseed and water at the ratio of 1 to 3 wt/vl. All boiled samples were dried at room temperature. The oven heating of the seeds was also carried out using air forced oven drying (Behdad Co., BC Oven 70, 3493, Iran) at 65, 95 and or 125 °C for 4, 8 and 12 h. After each heat processing, all the samples were milled through a 2 mm screen using CyclotecTM milling machine and kept in refrigerator at 4 °C for subsequent gas production procedure. The gas production procedure was performed as described by Theodorou et al., (1994), using 500 mg DM of each samples in 4 replicates and 3 runs. Methane emission was determined using gas detector (SR2-BIO System, Sewerin, Germany). Results & discussion Dry matter disappearance (DMD) was significantly decreased from 1 to 2 hours of boiling and milled flaxseed had the water boiled flaxseed reduced significantly (P< 0.01) as the time of boiling increased (Table 1). Results of the present study showed that heat processing of flaxseed is capable of manipulating the extent of emitted methane in the medium. Roasting, boiling and oven drying efficiently decreased methane emissions by approximately, 25, 40 and 60 %, respectively. Addition of oilseed supplements to ruminant diets has been shown to decrease methane output in ruminants fed conserved forages (Sejian et al., 2011). Table 1 Dry matter disappearance (DMD %), methane emission (ml) and methane emission per DMD (ml/mg) of raw whole flaxseed and the physically heat treated whole flaxseed. parameters Raw flaxseed Time of roasting (min) Time of boiling (h) oven drying temperature (°C) SEM P-value of contrasts 2 6 1 2 65 95 125 1 2 DMD 52c 56b 50c 42d 37e 60a 60a 39e 1.50 0.01 0.01 Methane production 5.3a 4.7b 4.2c 2.9c 2.4 1.6c 1.7c 1.0d 0.04 0.01 0.01 Methane emission per DMD 0.021a 0.016b 0.017b 0.014c 0.013c 0.005b 0.005b 0.005b 0.00 0.01 0.01 SEM: Standard error of mean; a,b,c,d,e Rows with different superscripts are statistically different (P< 0.05) 1: Raw flaxseed vs. Heat processing; 2: Roasting vs. Boiling and Oven Drying Conclusion It has been concluded both in vitro rumen fermentation and methane emissions of flaxseed were impacted by physically heat processing the seeds. In addition, the gas production constant rate of milled flaxseed was higher than those of the roasted flaxseed at 6 and 8 minutes. Rumen fermentation also significantly decreased as the time of boiling increased, while roasting did not make any significant decrease. Oven drying caused a reduction in dry matter disappearance of flaxseed. Methane emissions decreased in the boiled and oven dried seeds. References Matheson EM 1976. Flaxseed. In: EM Matheson (ed.) Vegetable Oil Seed Crops in Australia, Holt, Rinehart and Winston, Sydney, Australia, 111-121. Sejian V, Larkitz J, Ezeji T and Lal R 2011. Research Veterinary Science 4, 1–8. Theodorou MK, Williams BA, Dhanoa MS, McAllan AB, and France J 1994. Animal Feed Science and Technology 48, 185-197.

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