饲粮能量水平对育肥后期锦江牛营养物质表观消化率、瘤胃发酵及血清生化指标的影响

本试验旨在探讨饲粮能量水平对育肥后期锦江牛营养物质表观消化率、瘤胃发酵及血清生化指标的影响。试验选取育肥后期、体重相近(355.94±35.11)kg]的锦江牛35头,分为5组,每组4个重复,每个重复1~2头牛。按照《肉牛饲养标准》(NY/T 815—2004)中350 kg肉牛日增重(1.2 kg/d)所需净能的100%(A组)、106%(B组)、112%(C组)、118%(D组)、124%(E组)配制5种不同能量水平的饲粮,5种饲粮的综合净能(NEmf)分别为6.21、6.58、6.95、7.33、7.70 MJ/kg,粗蛋白质水平一致。预试期10 d,正试期128 d。结果表明:1)随着饲粮能量水平的提高,B组和E组平均日增重最高,但与其余各组相比差异均不显著(P>0.05);B组平均干物质采食量最高,但各组间差异不显著(P>0.05);与A组相比,其余组料重比均显著降低(P<0.05)。2)随着饲粮能量水平的提高,各组间营养物质表观消化率差异不显著(P>0.05)。3)与A组相比,D组和E组瘤胃液pH显著降低(P<0.05);B组和C组瘤胃液氨态氮含量显著低于其余各组(P<0.05);各组间瘤胃液菌体蛋白含量差异不显著(P>0.05),但B组数值最高;随着饲粮能量水平的提高,各组瘤胃液总挥发性脂肪酸含量呈上升趋势,其中B组瘤胃乙酸/丙酸显著低于A组(P<0.05)。4)B组和C组血清葡萄糖含量较A组分别显著提高了19.38%和14.72%(P<0.05);B组、C组和D组血清尿素氮含量较A组显著降低(P<0.05),而血清谷丙转氨酶活性和高密度脂蛋白含量较A组显著升高(P<0.05)。综上所述,本试验条件下,随着饲粮综合净能水平的提高,未对各组育肥后期锦江牛的营养物质表观消化率造成显著性影响。但适宜能量水平的饲粮有助于瘤胃微生物蛋白的合成和氨态氮的利用,同时有助于提高锦江牛的生长代谢水平,从而提高生产效益。结合各项指标得出,综合净能为6.58 MJ/kg比较适宜育肥后期锦江牛的生产需要。

Effects of Dietary Energy Level on Nutrient Apparent Digestibility,Rumen Fermentation and Serum Biochemical Indexes of Jinjiang Cattle in Later Stage of Fattening

The purpose of this study was to investigate the effects of dietary energy level on apparent digestibility of nutrients,rumen fermentation and serum biochemical indexes of Jinjiang cattle in the later stage of fattening.A total of 35 cattle with a similar body weight of(355.94±35.11)kg in the later stage of fattening were divided into 5 groups with 4 replicates in each group and with 1 or 2 cattle in each replicate.Five test diets with different energy levels were prepared according to Standard of Beef Cattle Breeding(NY/T 815-2004)in the 350 kg of beef cattle daily gain of 1.2 kg/d required for 100%of the net energy(group A),106%(group B),112%(group C),118%(group d),124%(group E),the comprehensive net(NEmf)of those five test diets were 6.21,6.58,6.95,7.33 and 7.70 MJ/kg,respectively,and the crude protein levels were consistent.The pretest period was 10 days and the pretest period was 128 days.The results showed as follows:1)with the increase of dietary energy level,average daily weight gain in groups B and E was the highest,but the difference was not significant compared with other groups(P>0.05);the average dry matter intake was the highest in B group,but there was no significant difference among groups(P>0.05);compared with group A,the feed/gain in other groups was significantly reduced(P<0.05).2)With the increase of dietary energy level,there was no significant difference in nutrient apparent digestibilities among groups(P>0.05).3)Compared with group A,the pH in groups D and E was significantly reduced(P<0.05);the content of ammoniacal nitrogen in groups B and C was significantly lower than that in other groups(P<0.05);there was no significant difference in mycoprotein content among groups(P>0.05),but the highest value was found in group B;the total volatile fatty acid(TVFA)content in each group presented an upward trend,and the acetic acid/propionic acid in group B was significantly lower than that in group A(P<0.05).4)The serum glucose content in groups B and C increased significantly by 19.38%and 14.72%,respectively compared with the control group(P<0.05).The serum urea nitrogen content in groups B,C and D was significantly reduced compared with group A(P<0.05),while serum alanine aminotransferase(ALT)activity and high-density lipoprotein(HDL)content were significantly increased compared with group A(P<0.05).To sum up,under the conditions of this experiment,with the increase of dietary energy level,there is no significant effect on apparent digestibility of nutrients of Jinjiang cattle.The diet with appropriate energy level is helpful to improve synthesis of microprotein and utilization of ammonia nitrogen,improving the growth and metabolism level of Jinjiang cattle,which improve production efficiency.The NEmf of 6.58 MJ/kg is more suitable for Jinjiang cattle to be fattened in the later stage of fattening obtained by combining various indexes.