不同能量水平的象草饲粮对肉牛生长、消化及血清生化指标的影响

Influences of Elephant Grass Diet with Different Energy Levels on Growth, Digestion and Serum Biochemical Parameters of Beef Cattle

本试验旨在探讨在饲粮中应用玉米替代象草,增加能量水平对肉牛生长、消化及血清生化指标的影响,从而为肉牛育肥过程中合理使用能量饲料提供依据。选取30头21月龄左右的杂交公牛[(449.4±45.7)kg],随机分为3组,分别为低能组、中能组和高能组,对应饲粮干物质中玉米和象草的含量分别为12.5%、22.5%、32.5%和60.0%、50.0%、40.0%,每组10头。试验期45 d,其中预试期5 d,正试期40 d。正试期内测定平均日增重、料重比,并计算经济效益;最后5 d用全收粪法测定干物质表观消化率;最后2 d分别于晨饲前及晨饲后2.5、6.0 h测定瘤胃液pH;最后1 d采集血液用于测定血清生化指标。结果表明:1)平均日增重以高能组最高(1.31 kg/d),中能组次之(1.21 kg/d),低能组最低(0.96 kg/d),但各组差异不显著(P>0.05);各组干物质采食量、干物质表观消化率均为高能组>中能组>低能组,高能组与低能组差异显著(P<0.05),而料重比则反之;2)晨饲前瘤胃液pH以高能组最低,但各组间差异不显著(P>0.05);高能组、中能组晨饲后2.5和6.0 h瘤胃液pH显著低于低能组(P<0.05);3)经济效益以低能组最低,低能组毛盈利分别比高能组和中能组低46.10%和40.28%;4)各组血清生化指标差异均不显著(P>0.05)。综合得出,肉牛育肥期以象草为唯一粗饲料时,提高饲粮中玉米含量以增加能量水平提高了肉牛干物质采食量、干物质表观消化率、平均日增重和经济效益,降低了料重比;当饲粮中玉米含量达32.5%时对瘤胃发酵和肉牛健康也无不利影响,具有最大的养殖经济收益。

This study was conducted to research the influences of increasing dietary energy level by replacing elephant grass with corn on growth,digestion and serum biochemical parameters of beef cattle,aimed to provide a theoretical basis for optimum supplement of energy for beef cattle fattening.Thirty healthy crossbred beef cattle at 21 months of age with body weight of(449.4±45.7)kg were randomly allocated into 3 groups with 10 heads per group.The three groups were low energy(LE)group,medium energy(ME)group and high energy(HE)group,and the corresponding contents of corn and elephant grass in dietary dry matter were 12.5%,22.5%,32.5%and 60.0%,50.0%,40.0%,respectively.The experimental period lasted for 45 days including 5-day pre-trail period and 40-day trial period.Average daily gain(ADG),feed to gain ratio(F/G)and economic benefit were calculated during the trial period;dry matter apparent digestibility was measured by total fecal collection method at the last 5 days;rumen fluid pH of was measured before morning feeding and at 2.5 and 6.0 h after morning feeding at the last 2 days;blood sample was collected to measure serum biochemical parameters at the last day.The results showed as follows:1)ADG was the highest in HE group(1.31 kg/d)and the lowest in LE group(0.96 kg/d),and that in ME group was in the middle(1.21 kg/d),while there was no significant difference among groups(P>0.05);dry matter intake and dry matter apparent digestibility showed HE group>ME group>LE group,and the differences between HE group and LE group were significant,while F/G showed the opposite change;2)rumen fluid pH before morning feeding in HE group was the lowest,but the difference among groups was not significant(P>0.05);rumen fluid pH at 2.5 and 6.0 after morning feeding in HE group and ME group was significantly lower than in LE group(P<0.05);3)economy benefit in LE group was the lowest among three groups,and gross profit was lower than HE group and ME group by 46.10%and 40.28%,respectively;4)there were no significant differences of serum biochemical parameters among three groups(P>0.05).In conclusion,when elephant grass is used as the only forage in beef cattle fattening,dry matter intake,dry matter apparent digestibility,average daily gain and economic benefit are improved while F/G is reduced when increasing energy level by replacing elephant grass with corn;there are no adverse effects on rumen fermentation and animal health even though corn occupies 32.5%of diet,and the best economic benefit is obtained.