A Study On The Effects Of Feeding Behavior On The Growth Performance And Social Rank Of Boars

Animals obtain energy and nutrients through feeding behavior,which affects individual growth and development.Pigs are gregarious animals,and competition in resources of gregarious pigs will affect their feeding behavior leading to the difference of the feeding behavior and growth performance of different rank pigs in herd.Investigating the impact of feeding behavior of boar on their growth performance and social rank has important economic significance in understanding the feeding patterns,exploring growth potential,mastering the social hierarchy,and formulating new breeding goals.This study took Dan Duroc,Landrace and Large White boars as research objects,and analyzed the original feeding data during the measurement period,as well as the leaves the starting and ending body weight,eye muscle area,back fat thickness,etc;consequently obtained seven feeding behavior indices including average daily feed intake（ADFI）,number of visits to the feeder per day（NVD）,time at the feeder per day（TFD）,feed intake per visit to the feeder（FIV）,time at the feeder per visit（TV）,feeding rate（FR）,index measuring the irregularity of feed intake（IIFI）,and six growth performance indices including days to 30kg body weight(D_{30 kg}),days to 100kg body weight(D_{100 kg}),average daily gain（ADG）,100kg backfat thickness（BFTC）,feed conversion ratio（FCR）and eye muscle area（EMA）.The main research content and results are as follows:Study One:The influences of boars feeding behavior on its growth performance.（1）General patterns of feeding behavior and growth performance in boars:both feeding behavior and growth performance had higher variation coefficients（5%～40%）by descriptive statistics;growth performance had a moderate heritability（h²=0.14～0.58）,while feeding behavior had a moderately high heritability（h²=0.22～0.58）by estimating genetic parameters from multi-traits mixed linear models;feeding behavior and growth performance of boars in three breeds had similar changing patterns by analysis changing patterns.From 0 to 24 o’clock,the FIV and TV of boars peaked from 7:00 to 10:00 am and14:00 to 16:00 pm,and the NVD,from 6:00 to 8:00 am and 16:00 to 18:00 pm.During the90～150 days of boar,with the increase of days,FIV and FR increased linearly,TV decreased gradually,NVD decreased first and then tended to be stable,ADG increased gradually and tended to be stable during 116-124 days,and FCR increased gradually.Feeding behavior in boars had high breeding potential and tends to change into a pattern of large single feeding intake and fewer feeding times,with dwindling feed utilization efficiency.（2）It’s about correlation analysis of feeding behavior and growth performance of boar.The results showed that ADFI was significantly positively correlated with FCR,ADG and RFI（P<0.05）,and negatively correlated with D_{30 kg},D_{100 kg};TFD was significantly positively correlated with FCR（P<0.05）;FR was significantly negatively correlated with D_{100 kg}（P<0.05）.Boars with high feeding intake,short feeding time,and fast feeding rate had better growth performance.（3）It’s about further exploration of total feed intake,NVD and TV of boar.Under the same total feed intake,the more NVD and the longer TV of boars were,the smaller ADG,the more D_{100 kg} days and the lower FCR were.Duroc boars with NVD less than 4.15 had shorter D100 kg,smaller BFTC and larger EMA（P<0.05）.Landrace boars with NVD less than 6.48 had larger EMA（P<0.05）.Large White boars with NVD less than 6.80 had shorter D100 kg,smaller FCR and larger EMA（P<0.05）.Meanwhile,the effective TV respectively was 22 min,23 min and 21 min for Duroc,Landrace boars and Large White.（4）It’s the analysis the IIFI of boar.The results showed that the IIFI of Duroc boar was the highest,followed by Large White boar the lower and Landrace boar the lowest,and furthermore IIFI was positively correlated with D_{100 kg},BFTC and FCR,and significantly negatively correlated with ADG（P<0.05）.Regular feeding patterns were beneficial to improve the growth performance of boars.Study Two:The effects of boars feeding behavior on their social rank.Social rank of boars was divided based on the criteria of feeding time sequence,daily feeding intake,and daily feeding time.boars with feeding time sequence in the front,higher daily feeding intake,and longer daily feeding time were classified as high social rank boars.（1）It’s the analysis of the feeding behavior and growth performance of high and low social rank boars.The results showed that the AW,ADG,EMA,and BFTC of high social rank boars were significantly higher than the low ones（P<0.05）,while D_{100 kg} and FCR were significantly lower than the low ones（P<0.05）.（2）It’s the analysis of the factors affecting the social rank of boars.When the feeding density was 9 pigs per pen in the experimental field,the ADG was higher and D_{100 kg}was shorter,and there was no difference in growth performance between high and low social rank boars in the pen,and mixed feeding of Duroc boars and Large White boars in a pen was beneficial to the growth and development of Large White boars.In summary,the conclusions of this study are:（1）the feeding behavior and growth performance indicators of boars have a low selective breeding degree,and furthermore the larger the TFD,FR,and IIFI,the worse the FCR and ADG of the boars.（2）More NVD and longer TFD of boars are not conducive to growth and development,moreover,NVD and TFD belongs to moderate and high heritability.Duroc pigs with NVD less than 4.15 and effective TV of 22 minutes;Landrace pigs with NVD less than 6.48 and effective TV of 23minutes;and Large White pigs with NVD less than 6.80 and effective TV of 21 minutes can obtain greater growth performance.（3）High social rank boars have better growth performance,and the feeding density of 9 boars per pen and the mixed feeding of Duroc boars and Large White boars can better stimulate the growth potential of boars.