Inaugural ASAS–CAAV Asia Pacif ic Rim Conference Abstracts

M206 Effect of a new urea-mineral slow-release compoundon fermentation characteristics with rumen-fistulated yaks. H.P. Jiao* 1 ,X.Q. Zhao 2 , B. Xue 1,2 , S.X. Xu 2 , and R.J. Wang 1 , 1 Animal Nutrition Institute,Sichuan Agricultural University, Sichuan Province, China, 2 Northwest Instituteof Plateau Biology, Chinaese Academy of Sciences, Qinghai Province, China.Animal nutritionists have evaluated many non-protein N (NPN) compounds asruminant feeds, with slow-release trait in rumen for optimizing efficiency of NPNutilization. Many slow-release urea products have been developed during therecent years, including isobutylidene diurea, methenamine, acetylurea, starea, andlinseed-coated urea, biuret, polymer-coated urea, and formaldehyde-treated urea(Golombeski, 2006). Many reports proved that mineral elements such as S, P, Cucan promote the synthesis of microorganisms (Thomas, 1950; Guterrez, 1996).The objective of this study was to evaluate the effect of a new urea-mineral slowreleasecompound on fermentation characteristics with rumen-fistulated yaks.Three rumen-fistulated yaks were subject to a 3(diet)×3(period) Latin Squaredesign. The three diets (concentration/roughage was 40%/60%,DM) wereformulated to be iso-nitrogen (CP = 18.26%) and iso-energy (NEm = 8.5MJ/kg).Urea-mineral slow-release compound (SRU, contains five primary elements N,30.46%; P, 3.23%; S, 3.82%; Cu, 0.1%; Ca, 4.76%; N:S = 8:1), urea phosphate(UP), and soybean meal (SBM) were used as dietary N source. During the lastday of each period, rumen liquor samples (10 mL) were taken before and 1, 2, 4,6, 8, 10, 14, 18 and 24 h after morning feeding (0900 h), for the determination ofpH, ammonia, and microbial crude protein with pH meter, chloride colorimetry,and RNA marker, resp. Statistical analysis was performed using SPSS16.0. TheNH 3-N concentration of SBM reached a peak at 1 h, whereas UP and SRUpeaked at 2 h. NH 3-N concentration for UP showed a fastest increase tendencyto the maximum at 2 h, which was 97.14% and 60.92% higher (P < 0.01) thanthat of SBM and SRU, respectively (Table 1). All 3 groups had a maximum at10 h, and MCP production was 19.74 mg/mL for SRU, higher (P < 0.01) thanthat of SBM (16.46 mg/mL) and UP (17.81 mg/mL). SRU in this study gave acomparatively stable rate of NH 3-N release and therefore was beneficial to MCPsynthesis. The release rate of NH 3in SRU was more gentle and conducive andtherefore redounds to MCP synthesis. These results proved that SRU is a goodN source for ruminants.Table 1. Effect of N source on some fermentation parameters1 2 4 6 8 10 14 18 24Ammonia(mg/100 mL)SBM 13.6 a 12.9 a 8.52 a 3.5 a 2.8 a 4.1 a 5.1 a 6.8 a 7.4 aUP 5.6 b 25.7 b 15.17 b 6.9 b 4.0 b 4.5 a 1.7 b 2.6 b 5.9 bSRU 7.5 a 12.4 a 12.5 b 4.5 c 2.2 c 2.3 b 3.0 c 3.0 c 4.9 cMicrobial crudeprotein (mg/mL)SBM 6.8 a 7.2 a 7.7 a 8.4 a 13.8 a 16.5 a 11.5 a 9.9 a 6.9 aUP 10.7 b 11.6 b 12.3 b 12.9 b 14.8 b 17.8 b 17.8 b 15.9 b 11.1 bSRU 11.3 b 11.9 b 12.6 b 14.4 c 17.1 c 19.7 c 17.5 b 13.2 c 10.3 ba–cMeans within row with different superscript have extremely significantdifference (P < 0.01).Key Words: urea-mineral, slow-release, rumen fermentation52