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本试验在湿热条件下,探究饲喂不同物理形态的开食料对犊牛生长发育、瘤胃发酵及血液指标的影响。试验采用36头荷斯坦母犊牛,随机分为3组(每组12头),分别自由采食颗粒状开食料(PSA)、粉末状开食料(PSB)和多颗粒状开食料(TS)。试验期63 d,其中1~42日龄为正常饲喂牛奶时期(断奶前期);43~49日龄为断奶期;50~63日龄为断奶后期。开食料从犊牛5日龄开始自由采食。在1、42、49以及63日龄晨饲前进行采血和称重,49和63日龄晨饲前胃管法采集瘤胃液。试验期间每天记录采食量和温湿度指数。结果表明,在湿热环境下:1)断奶期和断奶后2周TS组开食料干物质采食量、平均日增重和重料比高于PSA和PSB组,PSB组最低,但差异不显著(P>0.05)。2)TS组犊牛初次反刍时间较PSA组提前3.8日龄,较PSB组提前4.7日龄,差异均显著(P<0.05)。63日龄时,TS组瘤胃液氨氮含量显著低于PSA组(P<0.05)。3)42日龄时PSA组犊牛血液免疫球蛋白G含量显著高于TS组(P<0.05)。4)TS组犊牛初始腹泻时间较PSA和PSB组分别晚0.44和1.75日龄,但无统计学差异(P>0.05),TS组腹泻率最低。综合得出,湿热环境下,多颗粒状开食料较颗粒状开食料和粉末状开食料更能促进犊牛的生长发育,使犊牛尽早产生反刍行为,从而加快瘤胃功能的完善
In this experiment, we studied the effects of feeding different physical forms on the growth, rumen fermentation and blood parameters of calves under hot and humid conditions. Thirty-six Holstein calves were randomly divided into three groups (12 in each group): free-pellets (PSA), powdered starter (PSB) and multigrain starter (TS) . The experimental period was 63 days, of which, the period from 1 to 42 days was normal milk feeding period (pre-weaning); the weaning period was from 43 to 49 days; the post-weaning period was from 50 to 63 days. Open food from the calf 5 days free to eat. Blood samples were weighed before morning feeding at 1, 42, 49 and 63 days of age, and rumen fluid was collected by morning gastric feeding at 49 and 63 days of age. Feed intake and temperature and humidity index were recorded daily during the experiment. The results showed that: 1) At dry weaning and 2 weeks after weaning, the feed intake dry weight, average daily gain and weight-to-weight ratio of TS were higher in TS group than in PS and PSB groups, but the difference was not significant (P> 0.05). 2) The initial rumination time of calves in TS group was 3.8 days earlier than that of PSA group, which was significantly earlier than PSB group (P <0.05). At 63 days of age, the ammonia nitrogen content of rumen fluid in TS group was significantly lower than that in PSA group (P <0.05). 3) The serum immunoglobulin G of calves in PSA group was significantly higher than that in TS group on the 42nd day (P <0.05). 4) The initial diarrhea time of calves in TS group was 0.44 and 1.75 days later than that in PSA and PSB groups respectively, but there was no significant difference (P> 0.05). The diarrhea rate in TS group was the lowest. The results showed that under the hot and humid environment, the multi-granular food-opening material can promote the growth and development of the calf more than the granular food-opening material and the powdered food-opening material, so that the calf could produce rumination as soon as possible, thus accelerating the improvement of the rumen function