Influence On Growth And Development Of Male Holstein Calves Fed Different Nutrient Levels Of Milk Replacers

To study the influence on growth, apparent nutrient digestibility and serumbiochemistry indexes of male Holstein calves fed different nutrient levels of milkreplacer, forty healthy male Holstein calves with similar birthday and body weight wereselected and randomly divided into4groups according to a single factorial design. Thenutrient levels of milk replacer were as follows: control group (EE16%,CP24%),groupⅠ(EE13%,CP22%),group Ⅱ (EE16%,CP24%), group Ⅲ (EE19%,CP26%). The resultsshowed that:(1)With the increase nutrient levels in milk replacer, average daily gain (ADG)gradually increased. Compared with group Ⅰ, ADG of group Ⅱ, group Ⅲ respectivelyincreased by35.45%(P<0.05),37.64%(P<0.05). Average body height, average bodylength, average heart girth, and average circumference of cannon bone of calves were nosignificantly different among all the groups (P>0.05). Feeding higher nutrient level milkreplacer could decrease calves diarrhea.(2) The apparent digestibility of crude protein (CP), ether extract (EE), dry matter(DM) of calves rose first then fell as nutrient levels in milk replacer increased, but theapparent digestibility of Ca, P reduced step by step. In the experiment, the apparentdigestibility of CP, EE and DM in group Ⅱ was the highest, then was group Ⅰ, the lastwas group Ⅲ under different nutrient levels. However, the apparent digestibility of groupⅡ was higher than control group at the same nutrient level. Between11to30days old,the apparent digestibility of CP, EE and DM of calves in group Ⅱwere respectively69.95%,80.82%,68.15%, enhanced by5.60%(P<0.01),10.08%(P<0.05),4.96%(P<0.01) than group Ⅰ, increased by7.17%(P<0.01),11.72%(P<0.01),7.15%(P<0.01) than group Ⅲ; The apparent digestibility of CP, EE and DM of calves ingroup Ⅱ improved by1.33%(P<0.05),13.61%(P<0.01),1.38%(P>0.05) than controlgroup under the same nutrient level. Between30to45days old, when the nutrient levelwas different, the apparent digestibility of CP, DM of calves in group Ⅱwere the highest,their values were separately74.32%、74.79%, increased by4.05%(P<0.01),1.77%(P<0.01) than group Ⅰ, enhanced by5.81%(P<0.01),4.76%(P<0.01) than group Ⅲ.The apparent digestibility of Ca, P of calves in group Ⅰwas the highest, whereas there was no significant difference between control group and group Ⅱ.(3) The concentration of IgG and IGF-1in serum rose with nutrient level. At30-dayold, compared with group Ⅰ, the concentration of IgG in serum of group Ⅱ, group Ⅲseparately increased by11.53%(P<0.01),11.24%(P<0.01); The concentration of IgG ingroup Ⅰreduced by9.16%（P＜0.05）than control group. The concentration of IGF-1inserum of group Ⅱand group Ⅲ increased by5.78%(P<0.05),10.92%(P<0.01) thangroup Ⅰ; The concentration of IGF-1in serum of group Ⅲ improved by7.63%(P<0.01)than control group. At45days old, compared with group Ⅰ, the concentration of IgG ofgroup Ⅱand group Ⅲ increased by9.14%(P<0.01),11.08%(P<0.01); the concentrationof IgG of group Ⅰsignificantly decreased by6.72%(P<0.01) than control group. At30-day old, nutrient levels had no effect on AKP, T-AOC and NO; at45days old ofcalves, the concentration of AKP, T-AOC and NO rose with nutrient level increasing.Compared with group Ⅰ, the concentration of AKP of group Ⅱ, group Ⅲ enhanced by38.09%(P<0.05),42.83%(P<0.05); The concentration of AKP of group Ⅲ increased by21.51%(P<0.05) than that of control group. Compared with group Ⅰ, the concentrationof T-AOC of group Ⅱ, group Ⅲ enhanced by11.72%(P>0.05),18.33%(P<0.05). Theconcentration of NO of group Ⅱ, group Ⅲ improved by11.69%(P<0.05),7.80%(P<0.05) than that of group Ⅰ. Compared with control group, the concentration of NO ofgroup Ⅰdecreased by9.68%(P<0.05).(4)Compared to control group, starter intake ofgroup Ⅰ, group Ⅱ andgroup Ⅲrespectively increased38.72%(P>0.05),28.22%(P>0.05) and47.43%(P<0.05), and nodifference was found among the other three groups. Average weaning days of controlgroup was52d, the other three groups was46d, shortening6d than the control group.(5)The cost of raising one calf was respectively379.30yuan,315.52yuan,326.54yuan and342.27yuan. The cost of group Ⅰof a calf gain one kilogram was28.68yuan, increased by4.86%, while group Ⅱa ndgroup Ⅲ was respectively21.92yuanand22.61yuan, decreased19.85%and17.33%than control group.The study showed that: ADG increased as nutrient level increased, strengtheningcalves immunity, and decreasing calves diarrhea. Calves got the highest apparentdigestibility when the nutrient level was moderate. Comprehensive analysis from calfperformance and economic effectiveness of different nutrient levels, the best nutrientlevel was EE16%, CP24%.