Determination Of Common-used Feedstuffs MG Values And Influences Of Corn Of Different Processing And Forages Associative On MG Of Dairy Cows

This paper consisted of three parts:PartⅠ: Establishment of mathematical models of propionic acid yields in the rumen based on some feed nutrients parameters by in vitro technique.Eleven nutrition feed ingredients in four feed species were determined according to CNCPS the base in Exp1.Propionic acid production of the common-used feedstuffs were determined by in vitro technique.Two Holstein cows fitted with permanent cannulas in the rumen was used as a rumen fluid . The regression modeles were established based on CNCPS. The results showed that :(1) data for propionic acid production of each 400mg of corn, wheat bran, soybean meal,wine lees,flaxseed meal and sunflower feed meal after fermented in vitro for 16h were 0.53,0.35,0.35,0.47,0.45 and 0.33 mmol respectively; while data for propionic acid production of each 400mg of alfalfa hay,hay,corn silage,potato stems and corn stavers after fermented in vitro for 24h were 0.19,0.27,0.39,0.24 and 0.21mmol respectively.(2)The regression models of propionic acid production were established based on the nutrient ingredients of the feeds for concentrates and forages after listed as follows fermented for 16h and 24h respectively and the models were Concentrate ForagePartⅡ: Determination of MG of the common-used feedstuffs for dairy cows Exp1: Measurement of amount of rumen bypass starch and its digestibility in common-used feedstuffs for dairy cowsTwo lactating cows fitted with permanent rumen cannulas, with similar age, weight and average daily milk production were used for and fed a diet with 55:45ratio of concentrate to forage. The amount and degradability of the rumen bypass starch of the common-used feedstuffs for dairy cows and their degradation rates were determined. The maize had the highest amount of the bypass starch(406.79g/Kg), while flaxseed meal and corn stavers the lowest( 48.97g/Kg and 46.44g/Kg respectively), and the degradation rates of others were: wheat bran 217.11g/Kg,soybean meal 86.38 g/Kg,wine lees 139.25g/Kg,sunflower feed meal 113.73 g/Kg, alfalfa hay 31.56g/Kg,hay 87.26g/Kg,corn silage 56.07 g/Kg and potato stems 96.29 g/Kg. Soybean meal had the highest starch degradation rate, while potato stems the lowest, and the starch degradation rates of other feeds were wheat bran 63.78%,wine lees 59.38%,flaxseed meal 69.18%,sunflower feed meal 45.18%,alfalfa hay 45.39%,hay 59.35% and corn stavers 57.07%.Exp 2: In digestion rates of the rumen bypass starch of the common-used feedstuffs in the small intestine of the dairy cowsThe digestibility of the rumen undegraded residue of corn were determing was treated by freeze-dried intestine fluids of dairy cattle(FID). The result showed the optimal condition for determine the digestibility of the corn starch residue in the small intestine by FID was 0.3gFID/0.5gfeedingstuff,McDougall buffer,pH 7.0,Ca2+ 680uM, 39℃and the optimal fermentation time is 18h.The digestibility of rumen bypass starch of the different feedstuffs were as flow corn 47.18%,wheat bran 15.81%;soybean meal 37.29%,wine lees 15.68%,flaxseed meal 31.77% and sunflower seed meal 14.13%.Exp3: In according to the results above and the absorption rate of propionic acid through the regression models of propionic acid production and absorption of sheep given by Han Fei(2001), the MG of the common-used feeds for dairy cows were calculated, the result showed that the order for MG content in the different feeds was as follows, corn >wine lees >wheat bran >flaxseed meal >soybean meal >sunflower feed meal, the corresponding values well 276.03g/Kg, 100.76 g/Kg, 95.33 g/Kg, 92.06 g/Kg, 91.68 g/Kg and 72.67g/Kg respectively. the order of MG in the five forages was as follows: corn silage >hay>potato stems >corn stavers > alfalfa hay, corresponding values were 67.23 g/Kg, 43.97 g/Kg, 37.76 g/Kg, 33.63 g/Kg and 28.63 g/Kg respectively.PartⅢ:The effects of different processing techniques for corn and associative effect with forages on the MG valuesIn this experiment two Holstein cows fitted with permanent cannulas in the rumen were selected with the similar age, weight and average daily milk production and fed diet with forage and concentrate ratio of 55:45. The MG of corn treated different processing techniques such as expanded,baked,roasted,staved and the different forage combina -tions(alfalfa hay + silage corn + corn stalks(A 0:4:6 B 0:6:4 C 1:3:6))were used by to determine by in vitro,in situ and FID metheds. The results showed tha(t1) the MGs of the processed corn>roasted corn>baked corn>staved corn>expanded corn ,corresponding values were 276.03g/Kg,244.46 g/Kg,211.91 g/Kg,209.23 g/Kg and 159.21 g/Kg respectively which indicated that the processingof the corn reduced its MG; the order of MG in forage combinations was C>A>B and the corresponding values were 49.27 g/Kg,40.37 g/Kg and 38.75 g/Kg, indicating improvement MG in the roughages by combination.