Effects Of Niacin Acid On Production Performance And Rumen Fermentation In Vitro Of Beef Cattle Under High Level Of Concentrate Condition

The experiment was conducted to examine the effects of adding different amountnicotinic acid on production performance and fermentation parameters of rumen in beefcattle under high level of concentrate condition (fine thick than for85:15). There are thereparts in this study:(1) Effect of niacin on the performance, nutrient digestibility and serumbiochemical parameters of beef cattle under high level of concentrate condition;(2) Effectsof adding different amount nicotinic acid on the degradation rate nutrients in diets highlevel of concentrate condition in vitro culture;(3) Effects of adding different amountnicotinic acid on the fermentation parameters in diets high level of concentrate condition invitro culture.Experiment1: Using of single factor test design,30bulls (Simmental×Chinesecattle) with an initial weight of400kg were randomly divided into5groups. Thetreatment Ⅰwas fed concentrate diet supplemented with1%NaHCO3as control group; thecattles in treatmentsⅡ, Ⅲ, ⅣandⅤ, which were dose niacin of200,400,600and800mg/kgDM respectively but without NaHCO3supplementation. The feeding trial includingpre-test period7days and positive test period56days and the dietary concentrate to forageratio was about85:15. The results showed:①Supplementing niacin increased theperformance of beef cattle. The effect of niacin mainly reflected in the first period of thistrial (1-28d) and the best response of promoting growth is Ⅴ, which is the highest averagedaily gain of1.92kg, the lowest average ratio of feed to gain of6.29：1, and better thanthose of group I by14.97%(P<0.05) and13.95%(P<0.05), the groups of II and Ⅲ were alittle lower than those of group I without significant difference (P>0.05).②With theincreasing of niacin in experimental groups (Ⅲ, Ⅳ andⅤ), the apparent digestibility ofCP and EE increased gradually. The apparent digestibility of DM, OM, ADF, NDF and P ofgroup Ⅴ were the highest ones (P<0.01), but there were no significant differences in othergroups (P>0.05). There was no significant difference in the apparent digestibility of Ca.The apparent digestibility of nutrients of group Ⅴ were all higher than those of the controlgroup besides CP and Ca.③There were no significant differences in the serumbiochemical parameters of β-HBA, HDL, LDL and GLU in all treatments(P>0.05). Whilecompared with the control group, the contents,serum of TG and TC decreased but nosignificant (P>0.05) and decreased significantly of T4and UN (P<0.05) and decreasedhighly significant of BIL (P<0.01). At the same time, the content serum of GH increasedsignificantly (P<0.05) and increased highly significant of NEFA (P<0.01). Experiment2: The objective of the studies were conducted to determine the effects ofadding different amount nicotinic acid on the degradation rate nutrients in diets high boars(fine thick than for85:15) in vitro culture. Four treatments (Ⅰ, Ⅱ, Ⅲ, Ⅳ was0,400,800and1200mg/kg DM of nicotinic acid) were designed according to design of single factorsand four levels. Each treatment was cultivated in vitro culture. After0,0.5,1,2,4,6,8,12,18and24h sampled and then determining the nutrient degradation rate. The experimentsshow:①There were no effect for rumen degradability of adding NA, but nutrientsdegradation rate were improved with training the extension of time, and was the most inthe cultivation of the24h.②Adding NA can improved degradations of nutrient andshowed a single peak curve, Ⅲ to achieve the highest. The DM, ADF and NDFdegradation rates of Ⅲ has the significant difference (P<0.05) or most significantly(P<0.01) with Ⅰin all times; The CP degradation rate of Ⅲ had the significant difference(P<0.05) with Ⅰin1,2,4,8,12and24h (P<0.05), but there was no significant difference inother times (P>0.05); The EE degradation rate of Ⅲ had the significant difference (P<0.05)with other groups only in4and24h.Experiment3: The objective of the studies were conducted to determine the effects ofadding different amount nicotinic acid on the fermentation parameters in vitro culture, andthe course same as test2. Each sampling, the flasks removed immediately measured pHvalue and other fermentation parameters. The experiments show: The treatment groups, pHand NH3-N concentration first and then decreased trend, the MCP and VFA concentrationrising trend, acetate to propionate ratio downward trend. At the same culture time, withnicotinic acid raise, the treatment groups, pH first and then decreased trend, which incultured for0.5,1,2,4and24h, part III and control groups was significant (P<0.05); theNH3-N concentration was significant (P<0.05) except cultured for12h; the MCPconcentration after cultured for8h; the TVFA was significant (P<0.05) or mostsignificantly (P<0.01); the acetate to propionate ratio of part III was lowest exceptcultured for8h and control groups was significant (P<0.05) or most significantly (P<0.01); the LD concentration of part III was lowest and control groups was significant(P<0.05) except cultured for1,4,6,12and18h.Under the conditions of this experiment and comprehensive analysis of all groups,productions performance and fermentation parameter index, nicotinic acid effect of800mg/kg dry matter was better in diets high boars (fine thick than for85:15) of the beefcattle.