Effects Of Different Energy And Protein Levels On Growth Performance And Nutrients Apparent Digestibility In Male Lambs Of Yanshan Cashmere Goat

The purpose of this experiment is to study the effects of different energy and protein levels of diets on growth performance and nutrients apparent digestibility in male lambs of Yanshan cashmere goat.Ninety 4-month-old weaned male lambs of Yanshan cashmere goat(15 kg)were randomly divided into 9 groups(10 lambs per group)with 9 different totally mixed diets granulated feed.This experiment was based on a 3×3(energy×protein)completely random experiment design,metabolism energy(ME)and digestible crude protein(DCP)were set to 2 factors in this study and 3 levels were established,this experiment was divided into two stages according to the body weight(BW)of cashmere goat,the first stage was from 15 kg to 25 kg BW,the metabolic energy(ME)in Diet 1 was formulated at 9.5,10.5 and 11.5 MJ/kg·DM,digestible crude protein(DCP)were 8.5%,9.5% and 10.5%,respectively;the second stage was from 25 kg to 35 kg BW,the diet was modified according to the first stage with ME of 9,10 and 11 MJ/kg·DM,DCP were 8.5%,9.5% and 10.5%,feeding trial and digestion-metabolism trial were conducted to measure the growth performance and nutrients apparent digestibility.The trial results showed that:(1)The period of from 15 kg to 25 kg BW:The dry matter intake(DMI)and feed to gain ratio(F/G)were decreased significantly(P<0.05)with the increase of dietary ME levels but no remarkable effect on average daily gain(ADG)(P>0.05);the dietary DCP levels improved the ADG with no significant difference(P>0.05),ADG of high DCP groups were extremely higher than those of low and medium DCP groups(P<0.05),the dietary DCP levels had no significant effect on DMI;there was no remarkable difference in ADG between Group Ⅸ(high energy and high protein)and Group Ⅵ(medium energy and high protein),ADG of Group Ⅸ and Group Ⅵ were significant higher than Group Ⅶ(P<0.05)and higher than the other 6 groups with no significant difference(P>0.05);the interactions of dietary ME×DCP had a remarkable effect on DMI(P<0.05)but no significant effect on ADG and F/G(P>0.05).The fecal energy and urinary energy were decreased significantly with the increase of dietary ME levels(P<0.05),but the gross energy(GE)apparent digestibility increased significantly(P<0.05);the dietary DCP levels and the interactions of ME×DCP had no significant effect on GE,fecal energy,urinary energy,digestible energy and GE apparent digestibility(P>0.05).The nitrogen(N)intake,fecal N and urinary N were decreased significantly with the increase of dietary ME levels but N apparent digestibility increased significantly(P<0.05),N apparent digestibility in high ME groups were extremely higher than those of medium and low protein groups(P<0.05);the N intake,digestible N,N apparent digestibility increased significantly with the increase of dietary DCP levels(P<0.05);N apparent digestibility in Group was the highest(70.88Ⅸ %),the interactions of ME×DCP had no significant effect on N metabolism(P>0.05).The apparent digestibility of dry matter(DM),organic matter(OM),ether extract(EE)and calcium(Ca)increased significantly with the increase of dietary ME levels(P<0.05);the dietary DCP levels and the interactions of ME×DCP had no significant effect on other nutrients apparent digestibility(P>0.05).(2)The period of from 25 kg to 35 kg BW:The DMI and F/G decreased significantly with the increase of dietary ME levels(P<0.05)but no significant effect on ADG(P>0.05);ADG increased first and decreased afterwards with the increase of dietary DCP levels,ADG and DMI in medium DCP groups were extremely higher than those of low and high protein groups(P<0.05);the ADG of Group(medium energy and medium protein group)was highest(222g/d)Ⅴ,the ADG of Group(medium energy and low protein group)was lowest(163.78g/dⅣ);the interactions of dietary ME×DCP had a remarkable effect on DMI(P<0.05)but no significant effect on ADG and F/G(P>0.05).The fecal energy decreased significantly with the increase of dietary ME levels but digestible energy and GE apparent digestibility increased significantly(P<0.05),GE apparent digestibility of high ME groups was 21.26% higher than low ME groups(P<0.05),there was no remarkable difference in urinary energy(P>0.05);the dietary DCP levels and the interactions of ME×DCP had no significant effect on fecal energy,urinary energy,digestible energy and GE digestibility(P>0.05).The dietary ME levels had a significant effect on nitrogen(N)intake,fecal N and N apparent digestibility(P<0.05)but no significant effect on urinary N,N Retention and net protein utilization(NPU)(P>0.05),the N intake and fecal N decreased significantly with the increase of dietary ME levels(P<0.05),digestible N had the trend to decrease(P>0.05),N apparent digestibility increased significantly(P<0.05),N apparent digestibility in high ME groups were extremely higher than low and medium ME groups(P<0.05),the dietary DCP levels significantly affected N apparent digestibility,urinary N,digestible N and N intake(P<0.05)but no significant effect on fecal N,N Retention and NPU(P>0.05),N apparent digestibility,urinary N,digestible N and N intake increased significantly in linear with the increase of dietary DCP levels(P<0.05);the interactions of ME×DCP had no significant effect on N digestion and metabolism(P>0.05).The dietary ME levels had a significant effect on the apparent digestibility of DM,OM,EE and Ca(P<0.05)but no significant effect on NDF,ADF,and P(P>0.05),the apparent digestibility of DM,OM,EE and Ca increased significantly with the increase of dietary ME levels(P<0.05);the dietary DCP levels had a significant effect on the apparent digestibility of Ca,Ca apparent digestibility in low DCP groups were extremely lower than those of medium and high protein groups(P<0.05).Comprehensive consideration,ME:10.5 MJ/kg and DCP:10.5% of diet are recommended for Yanshan cashmere goats from 15 kg to 25 kg BW,ME:10 MJ/kg and DCP:9.5% of diet are recommended for Yanshan cashmere goats from 25 kg to 35 kg BW.