开食料中不同NDF水平对犊牛生长性能、瘤胃内环境及血清生化指标的影响

为探索开食料中不同NDF水平对犊牛生长、瘤胃发酵参数以及血清生化指标的影响,选用初生重相近(42±2.5) kg、饲喂足量初乳的中国荷斯坦犊牛60头,其中公犊牛36头,母犊牛24头。随机分为A、B、C和D 4个处理组,每个处理15头,其中9头公犊牛+6头母犊牛,试验犊牛于犊牛岛(1.5 m×3.4 m)单独饲养。15日龄开始分别饲喂NDF水平不同的4种开食料,分别为:A处理10%,B处理15%,C处理20%和D处理25%,70日龄断奶,试验期112 d。结果表明:1)0~42日龄和70~112日龄,B组日增重均高于A、C和D组(P<0.05),分别高出45.69、39.79、117.13 g·d^-1和35.33、153.29、 145.93 g·d^-1。70~112日龄,B、C和D组开食料采食量显著高于A组(P<0.05),分别高出255.20、252.48和392.27 g·d^-1。A(0.61)和B(0.60)组犊牛的饲料转化率显著高于C(0.55)和D(0.54)组(P<0.05);2)犊牛瘤胃pH在35和70日龄时,C组显著高于其他3组(P<0.05),112日龄时,A和B组显著高于C和D组(P<0.05);3)瘤胃NH₃-N含量在90日龄前差异不显著(P>0.05),但在112日龄时, B、C和D组较A组显著降低16.72%、44.19%和52.10%(P<0.05);4)C和D组乙酸比例显著高于A和B组(P<0.05);B组丙酸比例较A、C和D组高出4.24%、3.18%和6.43% (P<0.05),乙酸/丙酸显著低于A、C和D组(P<0.05);5)各处理组间血清总蛋白、葡萄糖和尿素氮含量无显著差异(P>0.05)。1~3月龄犊牛开食料中NDF适宜水平为15%有利于提高断奶后日增重,促进饲料利用效率,改善瘤胃内环境,且对犊牛血清生化指标无不利影响。

Effects of different starter NDF levels on the growth performance,rumen environments and serum biochemical parameters of calves

The objective of this study was to determine the effects of different starter neutral detergent fiber (NDF) levels on the growth performance,rumen environments and serum biochemical parameters of calves.Sixty newborn Holstein calves (24 females and 36 males) with body weight (42±2.5) kg were randomly assigned to four treatment groups (A,B,C and D),with each group made up of nine males and six females.Each calf was housed individually in a 1.5 m× 3.4 m calves island at the experimental farm.Each group was fed one of four starters with different NDF levels of alfalfa hay and oat hay.The NDF levels of the starters were 10％,15％,20％ and 25％,respectively.The calves were weaned at 70 days of age and the experiment lasted for 112 days.The results were as follows.During 0-42 and 70-112 days of age,the average daily gains were 46.59,39.79,117.13 g · d-1 and 35.33,153.29,145.93 g · d-1 respectively higher in group B than in groups A,C and D (P＜0.05).During 70-112 days of age,the starter intake was significantly higher by 255.20,252.48 and 392.27 g· d-1 in groups B,C and D than in group A (P＜0.05).The A and B starters improved feed conversion ratios (P＜0.05).2) At 35 and 70 days of age,rumen pH was significantly higher in group C than in groups A,B and D (P＜0.05).At 112 days of age,rumen pH was greater for groups A and B than C and D (P＜0.05),and the ammonia nitrogen concentration was decreased by 16.72％,44.19％ and 52.10％ more in groups B,C and D respectively than in group A (P＜0.01).4) The proportion of acetate was significantly higher in groups C and D than in groups A and B (P＜0.01).The propionate ratio was significantly higher by 4.24％,3.18％ and 6.43％ in group B than in groups A,C and D (P＜0.05).The acetate to propionate ratio of group B was lower than the other groups (P＜0.05).5) No significant differences were observed in contents of total protein,glucose and urea nitrogen in serum (P＞0.05).In conclusion,starters with approximately 15％ NDF could increase Holstein calves' average daily weight gains and improve their feed conversion ratio and rumen environments,while they do not affect their serum biochemical parameters.