饲粮钴添加水平对断奶至3月龄獭兔消化代谢的影响

本试验旨在研究饲粮钴添加水平对断奶至3月龄獭兔饲粮营养物质表观消化率、氮代谢、胰腺消化酶活性、血清生化指标和钴代谢的影响。选择体重相近的断奶獭兔200只,随机分为5组,每组40个重复,每个重复1只试验兔。5组试验兔分别饲喂在基础饲粮中添加0(对照)、0.1、0.4、1.6、6.4 mg/kg钴(以硫酸钴的形式)的试验饲粮,经7 d预饲后进行为期53 d的饲养试验。结果显示:饲粮钴添加水平对饲粮中各营养物质的表观消化率均没有显著影响(P0.05),但饲粮干物质(DM)、粗蛋白质(CP)和钴的表观消化率随饲粮钴添加水平的升高均有先升高后降低的趋势,DM和CP的表观消化率在钴添加水平为1.6 mg/kg时最高,钴的表观消化率在钴添加水平为0.4 mg/kg时最高。饲粮钴添加水平对粪氮(FN)、可消化氮(DN)、氮表观消化率(NAD)、氮生物学效价(NBV)均无显著影响(P0.05),对食入氮(IN)、尿氮(UN)、氮沉积(RN)、氮利用率(NUR)有显著影响(P0.05)。随着饲粮钴添加水平的升高,IN、RN和NUR均先降低后升高再降低,并均在钴添加水平为1.6 mg/kg时最高,而UN则逐渐降低。饲粮钴添加水平对胰腺胰蛋白酶活性有显著影响(P0.05),且在钴添加水平为1.6 mg/kg时最高。饲粮钴添加水平对血清尿素含量有显著影响(P0.05),随着饲粮钴添加水平的升高,血清尿素含量先降低后升高,在钴添加水平为1.6 mg/kg时最低。饲粮钴添加水平对血清总蛋白和白蛋白含量无显著影响(P0.05)。饲粮钴添加水平对粪、尿、肌肉、脾脏和肾脏中钴含量有显著影响(P0.05),且随着饲粮钴添加水平的升高,粪、尿、肌肉、脾脏和肾脏中钴含量均持续增加。综合本试验测定指标,断奶至3月龄獭兔饲粮钴适宜添加水平为0.4~1.6 mg/kg(饲粮中钴含量实测值为0.60~1.83 mg/kg)。

Effects of Dietary Cobalt Supplemental Level on Digestion and Metabolism of Weaned to 3-Month-Old Rex Rabbits

This experiment was conducted to study the effects of dietary cobalt supplemental level on dietary nutrient apparent digestibility,nitrogen metabolism,digestive enzyme activities in pancreas,serum biochemical indices and cobalt metabolism of weaned to 3-month-old Rex rabbits.Two hundred weaned Rex rabbits with the similar body weight were randomly assigned into 5 groups with 40 replicates in each group and each replicate contained 1 rabbit.Rabbits in 5 groups were fed experimental diets which supplemented with 0,0.1,0.4,1.6 and 6.4 mg/kg cobalt ((in the form of cobalt sulfate)) on the basis of a basal diet,respectively.The trial lasted for 7 days for adaptation and 53 days for feeding test.The results showed that dietary cobalt supplemental level had no significant influence on dietary nutrient apparent digestibility (P＞0.05),but with the increase of dietary cobalt supplemental level,the apparent digestibility of dietary dry matter (DM),crude protein (CP) and cobalt tended to be increased firstly and then decreased,and the highest DM and CP apparent digestibility appeared in 1.6 mg/kg cobalt supplementation group and the highest cobalt apparent digestibility appeared in 0.4 mg/kg cobalt supplementation group.Dietary cobalt supplemental level had no significant influences on fecal nitrogen (FN),digestible nitrogen (DN),nitrogen apparent digestibility (NAD) and nitrogen biological value (NBV) (P＞0.05),but had significant influences on nitrogen intake (NI),urinary nitrogen (UN),retention nitrogen (RN) and nitrogen utilization rate (NUR) (P＜0.05).With the increase of dietary cobalt supplemental level,NI,RN and NUR tended to be decreased firstly and then increased,UN gradually tended to be decreased,and the highest NI,RN and NUR all appeared in 1.6 mg/kg cobalt supplementation group.Dietary cobalt supplemental level had significant influence on trypsin activity in pancreas (P＜0.05),and the highest value appeared in 0.4 mg/kg cobalt supplementation group.Dietary cobalt supplemental level had significant influence on serum urea (UR) content (P＜0.05),with the increase of dietary cobalt supplemental level,the serum UR content tended to be decreased firstly and then increased,and the lowest value appeared in 1.6 mg/kg cobalt supplementation group.Dietary cobalt supplemental level had no significant influences on serum total protein (TP) and albumin (ALB) contents (P＞0.05).Dietary cobalt supplemental level had significant influences on the content of cobalt in fecal,urine,muscle,spleen and kidney (P＜0.05),with the increase of dietary cobalt supplemental level,the content of cobalt in fecal,urine,muscle,spleen and kidney continued to be increased.Considering all indices of this experiment,appropriate dietary cobalt supplemental level is 0.4 to 1.6 mg/kg (the actual measured content of cobalt in the diet is 0.60 to 1.83 mg/kg) for weaned to 3-month-old Rex rabbits.