Effects Of Different Feeding Modes And Different Crude Protein Level Of The Artificial Crop Milk On Growth Performance And Intestinal Morphology In Squabs

Pigeons are altrices,which are difference from the other poultry.They have not opened their eyes when they break through their shells as well as they lack of the ability to walk and eat.The squabs need to rely on the milk of their parent pigeons for the whole process after they are hatched from the shells until they are put on the market.This leads to reduce annual output of each pair of parent pigeons,severely limits the number of hen pigeons production and restricts the development of the pigeon industry.Compared with the traditional parent-pigeon feeding,artificial feeding can not only improve effectively the uniformity of the pigeons,but also has other advantages,such as gain weight quickly,low mortality in the later period.However,at present,NRC and CRC have not given the standard of nutritional requirements for squabs,and the literature on the nutritional requirements of squabs is not consistent.Firstly,in this study I researched and contrasted the effects of different feeding modes for squabs and then study the effects of different crude protein levels of artificial crop milk on the growth performance of pigeons by feeding the artificial crop milk contains different levels of crude protein to squabs,clarify the reasonable crude protein level in artificial crop milk and provide reference for the preparation of scientific and reasonable crude protein levels of artificial crop milk.This research is divided into three parts:1.The effect of different feeding modes on the growth performance and intestinal function of the squabsIn the experiment,96 7-day-old squabs were selected,and they were randomly divided into an artificial feeding group and a parent pigeon feeding group.Each group has eight repetitions.The squabs in the parent pigeon feeding group were fed by parent pigeons,and each pair of parent pigeons feed 3 squabs.The parent pigeons are fed 50%pellets+50%raw grain.The raw grain consists of corn and peas.The parent pigeons eat freely.The others in the artificial feeding group was fed artificial crop milk three times a day.When the squabs were 25 days old,blood was collected from the carotid artery and then tissues and organs such as the duodenum,jejunum,ileum,and chest muscles are taken.The squabs were fed for 19 days in an environment with the average temperature of 27°C to 32°C and the relative humidity of 75%to 82%.The results show that:compared with the parent-feeding group,（1）the live weight,carcass weight,half eviscerated weight,and full eviscerated weight of squabs in the artificial feeding group were significantly higher（P<0.01）,and the carcass rate was significant increased（P<0.05）,the breast muscle rate of the squabs in the artificial feeding group was extremely significantly reduced（P<0.01）;（2）The spleen organ index of the squabs in the artificial feeding group was significantly increased（P<0.05）,and the muscles and the gastric organ index of the squabs was extremely significantly reduced（P<0.01）;（3）The Villous height/Crypt depth（V/C）of the duodenum of the artificial feeding group was significantly increased（P<0.05）,but the height of ileal villi and V/C of the ileum were significantly reduced(（P<0.05）;（4）The serum Malondialdehyde（MDA）content of the artificial feeding group of squabs were significantly lower（P<0.05）;（5）The brightness value of the flesh color in the artificial feeding group 45 minutes and 24 hours after slaughter was significantly reduced（P<0.05）,the yellowness value of meat color increased significantly（P<0.05）24 hours after slaughter.Above all,the artificial feeding mode improves the growth performance,slaughter performance and serum antioxidant capacity of the squabs,and the feeding effect is better than the parent-feeding mode.2.The effect of artificial crop milk with different crude protein levels on the growth performance and intestinal function of squabsIn the experiment,192 7-day-old squabs were randomly divided into four groups.Each group has eight repetitions.The metabolic energy of artificial crop milk was same,but the crude protein levels were 16.5%,18%,19.5%and 21%.They were fed artificially three times a day.On the 10^th,13^th and 16^th day of the experiment,feces and feed samples of each group of squabs were collected,blood samples were collected from the carotid artery of each group when the squabs were 25 days old.tissues and organs such as duodenum,jejunum,ileum,and chest muscles were collected.The results showed that:（1）There were no significant differences in the initial weight,final weight,average daily weight gain,average daily feed intake,and feed-to-weight ratio of each group of squabs（P>0.05）;（2）Carcass rate index:CP16.5%group and CP21%group were significantly higher than CP18%group and CP19.5%group（P<0.05）;semi-eviscerated rate index:CP16.5%group and CP19.5%group had significant difference（P<0.05）);chest muscle rate index:CP16.5%group and CP18%group,CP19.5%group,CP21%group squabs’breast muscle rate has no significant difference（P>0.05）,but CP21%group and CP18%group squabs’breast muscle rate has significant difference（P<0.05）.（3）The apparent metabolic rate of crude protein in each group was significantly different（P<0.01）,and the apparent metabolic rate of crude protein in the CP16.5%group was the highest;there was no significant difference in the crude fat metabolism rate between the groups（P>0.05）;The dry matter metabolism rate differed significantly among the 4 groups（P<0.05）.（4）Kidney organ index:CP16.5%group was significantly different from the other three groups（P<0.05）;Gastrointestinal organ index:CP16.5%group was significantly different from the other three groups（P<0.05）,and CP18%group,CP19.5%group and CP21%group were significantly different（P<0.05）;Bursal organ index:CP16.5%group had significant difference with CP18%group and CP19.5%group in bursal organ index（P<0.05）0.05),but it had no significant difference with the CP21%group（P>0.05）.（5）There was no significant difference in the amylase AMS and trypsin activities of the squabs in each group（P>0.05）.In the index of duodenal V/C indicators:CP16.5%group had no significant difference with CP18%group and CP19.5 group but it was significantly different from CP21%group（P<0.05）.（6）The index of MDA content in the serum of squabs:the CP16.5%group was not significantly different from CP18%group and CP19.5 group（P>0.05）,but it was significantly different from the CP21%group（P<0.05）,however,there was no significant difference between the CP18%group,CP19.5%group,and CP21%group（P>0.05）.（7）The redness of the flesh color of the squabs measured 24 hours after slaughter of the CP16.5%group was significantly different from the CP18%group and the CP19.5%group（P<0.05）,but it was not significantly different from the CP 21%group（P>0.05）;the yellowness value of the squabs in the CP16.5%group was not significantly different from the CP18%and CP19.5%groups after 21 hours of slaughter（P>0.05）,but it was significantly different from the CP21%group（P<0.05）;There was a significant difference between the CP21%group and the CP6.5%group,CP18%group and CP19.5%group in the sheer force of breast muscles of squabs（P<0.05）.The results show that artificial crop milk with different crude protein levels has no significant effect on the growth performance of the squabs.As the crude protein level of artificial crop milk increased,the carcass rate and breast muscle rate of the squabs increased,but the serum antioxidant capacity of the squabs decreased and the flesh color of the squabs becomes lighter.When the crude protein level of artificial crop milk is 16.5%,the crude protein metabolism rate is the highest,and it can also meet the nutritional needs of the growth and production of squabs.The recommended level of crude protein in artificial crop milk is16.5%,which can effectively reduce feeding costs.3.Design of a bionic artificial feeding machine for squabsIn the preliminary test process,it was found that the artificial feeding machines are used currently all have certain shortcomings,such as cumbersome operation、inaccurate feeding control,difficult control of feed temperature and difficult operation.Therefore,the artificial feeders currently used in this study have some disadvantages.Based on the feeding machine,a smarter and more accurate artificial bionic feeding machine for squabs is designed.The artificial bionic feeding machine for squabs consists of four parts:a feed mixing system,a feed conveying system,a feed insulation system and a bionic feeding system.The innovations and advantages of this experimental design are as follows:This experimental design can precisely control the feed flow rate and enable artificial feeding to achieve precise feeding;it can control the feed temperature and keep the feed temperature at the optimum temperature for the squabs,reducing the adverse effect of artificial feeding on the growth and production performance of the squabs;the design of the feeding gun in this experiment uses bionics technology to simulate parent pigeons to feed the squabs,reduce the stress of artificial feeding to the squabs,and realize intelligentized,accurate and welfare squab breeding.In summary,the artificial feeding mode improves the growth performance,slaughter performance and serum antioxidant capacity of the squabs,and the feeding effect is better than the parent pigeon feeding mode.When the crude protein level of artificial pigeon milk is 16.5%-21%,there is no significant difference in the effect on the growth performance of squabs.As the crude protein level of artificial crop milk increases,the carcass rate and breast muscle rate of the squabs will increase,but with the increase of the crude protein level of artificial crop milk,the serum of the squabs is anti-oxidant.Squabs will be in an unhealthy state.Ability is reduced,and the flesh color of the pigeon muscles becomes lighter.When the crude protein level of artificial crop milk is 16.5%,the crude protein metabolism rate is the highest.When the crude protein level of artificial crop milk is 16.5%,which can also meet the nutritional needs of the growth and production of squabs.The recommended level of crude protein in artificial crop milk is 16.5%,which can effectively save feed resources of protein.The crude protein level of artificial pigeon milk is 16.5%,which can reduce feed cost.Combined with the problems encountered in the early feeding experiment,a bionic artificial feeding machine for squabs was designed.