Studies On Establishing Of Methane Production Prediction Model And Influcencing Factors On Methane Production Of Grazing In Inner Mongolian Cashmere Goats

The papers divided into three parts. Part one was to establish methane production models for pastures grazed by Inner Mongolian Cashmere goats by use of nutritional values of pastures based on routine analysis and CNCPS. Part two was to determine methane production of Inner Mongolian Cashmere goats by Sulfur Hexafluoride (SF₆)tracer technique in order to validate above established models. Part three was to determine the methane production of Inner Mongolian Cashmere goats in different pastures growing periods and to study the influencing factors on methane production at different pastures growing periods,such as pH value rumen and other fermentation parameters in the rumen, nutritional composition and digestibility of pastures, phylogenic and population of methanogensPART I Established prediction models of methane production for pastures grazed by Inner Mongolian Cashmere goats.Nutritional composition of 31 species in 4 families growed in desert grassland were analyzed based on CNCPS and routine analysis, meanwhile methane production of the pastures was determined by in vitro gas production technique(IVGPT). The results showed that positive correlations were found between the methane production and CP content, IVDMD, IVDMR, but negative correlation between methane production and CHO of the pastures except CB2.The prediction models of the pastures methane production based on nutritional composition were as follows: Leguminous pastures: Y=-3.108-1.594CP+0.855NDF-1.193ADF-0.102IVDMR+1.266IVDMD(R²=0.999,n=7) Chico pastures: Y=69.544-1.059CP-0.473NDF+0.618ADF+0.812ADL-1.333NFE+ 0.349IVDMD(R²=0.940,n=10) Composite pastures: Y=100.117+0.687CP-1.139ADF-0.224IVDMR-0.575IVDMD(R²=0.995,n=6) Germanous pastures: Y=199.864+1.140CP-3.172NDF+1.417ADF-1.725ADL-0.845IVDMR+ 0.178IVDMD(R²=0.984,n=8) Prediction models of methane production based on CNCPS were as follows: Leguminous pastures: Y=88.501-3.234CA+0.577CB1-1.731CC+6.249PB1+40.381PB3-43.412PC(R²=0.999,n=7) Chico pastures: Y=54.5924+0.828CB1-0.193CC-2.130PA-0.565PB1+16.082PB3-15.717PC- 0.161CHO-0.431NFC(R²=0.986,n=10) Composite pastures: Y=38.783+0.130CB1-0.124CB2-0.529CC+1.051PB3-1.714PC (R²=0.999,n=6) Germanous pastures: Y=-410.282+0.530CA+3.613CB2+19.284CC-161.365PA+54.942PB1 -89.731PB3+45.747PC(R²=0.999,n=8)Part 2 Validation of the methane production prediction models. Four Cashmere goats, aged 1.5±0.21years and BW of 30±1.2 kg were used for measuring methane production for 6 diets by SF₆ tracer technique. The diets were Alfalfa dry (D1), Erect Milkvetch (D2), Wheatgrass (D3), Corn silage (D4), Corn straw (D5) and restricted feeding: 20%Alfalfa+80%Chinese Wildrye (D6), the methane production of the goats fed D6(M)at restricted feeding and D6(L)ad labium feeding was compared. The results showed that methane production determined by IVGPT were 20.62,17.23,19.01,19.74,17.01,17.12 and 16.44g/kgDM for D1,D2,D3,D4,D5,D6(M) and D6(L),the corresponding values by SF₆ trace technique were 21.02,19.39,20.26,20.37,17.99,18.06 and 17.71g/kgDM.There was significant correlation between the values measured by IVGPT and SF₆ techique,and the coefficient correlation was 0.941(P=0.002).Part 3 Study on determination of methane production of grazing Inner Mongolian Cashmere goats in different patures growing periods and influencing factors on methane production of grazing Inner Mongolian Cashmere Goats1 Dry matter intake, pasture botanical composition of grazing Inner Mongolian Cashmere goats were measured in different pastures growing periods (young, prosperity and dry period) using Alkane technique. Six Inner Mongolia Cashmere goats, aged 1.5±0.21years and BW of 25±1.2 kg were selected from BAYINHATAI Cashmere goats Breeding farm,in WULATEzhongqi, Inner Mongolian. The results showed that dry matter intake(DMI) at different pastures growing periods were 0.779,0.845 and 1.632kg/d respectively. Pasture botanical composition were Carex duriusula 13.42%,Artemisia frigida Willd 6.43%,Stipa breviflora 71.85%,Iris bungei maxim 3.93% and Peganum harmala L4.35% in young pasture period and Puncturevine Caltrop Fruit 7.9%,Peganum harmala L 42.28% Erodium stephanianum Willd 8.78%,Allium victorialis L 12.1%,Green Bristlegrass Herb 8.56% and Poa alpigena 20.4% in prosperity pasture period, Sweet Wormwood Herb 68.9%,Artemisia annua L 13.3% and Carex duriusula 17.82% in dry pasture period.2 Methane production of the grazing Inner Mongolia Cashmere goats at different pasture growing periods was measured by IVGPT. The methane production of the different pasture growing periods were 16.76g/d(young pasture period),19.02g/d(prosperity pasture period) and 33.92g/d(dry pasture period).3 Correlation analysis of dynamic changes of nutritional composition and digestibility of pastures and the methane production and influencing factors on the methane production in different pastures growing periods were studied by dynamic changes of nutritional composition and digestibility of the pastures grazed by Inner Mongolian Cashmere goats. The results showed that a positive correlation between the methane production per kg DMI and CP content of pastures was found, but there was a negative correlation with ADF and NDF content. However positive correlation was also found between the methane production (g/d) of Inner Mongolian Cashmere goats and ADF and NDF digestibility of pastures and there was negative correlation with CP and OM digestibility.4 Correlation analysis of rumen environment values and the methane production and influencing factors on the methane production in different pastures growing periods were studied by dynamic changes of fluids pH and other fermentation parameters in the rumen of Inner Mongolian Cashmere goats, including NH3-N content, pH value and volatility fatty acid (VFA).The results showed dynamic changes of pH values in the rumen had no significant between difference pastures growing periods and feedlot feeding periods, and had no significant impact on methane emission; the concentration of NH3-N in the rumen and CP content of pasture had a positive correlation with the methane production expressed as per kg DMI both in feedlot condition periods and grazing periods. The A/P ratio in the rumen in dry pasture period was significantly higher than that in young and prosperity pasture period, and the two values were higher than that in feedlot feeding periods, There was a positive relationship between A/P ratio and the methane production expressed as g/d both in different pastures growing periods and feedlot feeding periods.5 The methanogens phylogenic of Inner Mongolian Cashmere goats at different pastures growing periods was studied by MCRa gene method, and analysis of correlation with the methane production was made. The results showed that: In the rumen of Inner Mongolia Cashmere goats, there were at least 6 different gene styles at different pastures growing periods, sequencing analysis results showed the gene styles all belonged to uncultured styles, but there was 97% homology at some of different gene styles. There was no significant difference on methanogens species in the rumen at different pastures growing periods.6 The total methanogenes population was quantitated through fluor dye combined with Real Time PCR method at 2h before morning feeding and 0h,2h after morning feeding at different pastures growing periods and feedlot feeding periods .The results showed that at 2h after morning feeding in feedlot feeding periods, the population of methanogens was the the highest; the order of total methanogens population of three times was feedlot feeding periodsï¹¥young pasture periodï¹¥prosperity pasture periodï¹¥dry pasture period; and the methanogens population had no significant coefficient correlation between the methane production and values.