| The object of this study was to investigate the effects of energy restriction and compensation on growth performance,muscle quality and IGF-?m RNA expression of growing pigs.The experiment adopts a single factor test design.A total of 80 Duroc × Landrace × Large pigs with similar days old(85 ± 5)and weighs(35.30 ± 1.42 kg)were selected.According to the principle of body weight and gender consistency,pigs were randomly divided into 4 test groups(the Control Group,Group I: 10% energy-restricted,Group II: 20% energy-restricted,and Group III: 30% energy-restricted).There were 5 repetitions per group and 4 pigs per repetition.The experiment was divided into two stages: the restricted period and compensation period.During the restricted period(0-35 days),the Control Group were fed the basic diet,and the energy-restricted group fed the diet with energy restriction of 10%,20%,and 30%,respectively.The daily feeding amount of the restricted-feeding group refers to the feed intake of the Control Group on the last day.During the compensation period(36-80 days),each experimental group was fed basic diet freely.The pretest lasted for 7 days,and the experiment lasted for 73 days.The results showed that:(1)During the energy-restricted period,the ADG of pigs in each energy-restricted group showed a decreasing trend with the energy-restriction intensity,the F/G showed an increasing trend,especially in Group ? and ?(P < 0.05),and FBW of pigs in Group ? was significantly lower than the Control Group(P < 0.05).During the compensatory growth period,the ADG and F/G of pigs in each feed-restricted group were significantly improved compared to the energy-restricted period.The ADG and ADFI of pigs in Group ? were significantly higher than that of the Control Group(P < 0.05),and F/G was significantly reduced(P < 0.05).FBW of pigs in Group ? was significantly lower than that of other test groups(P < 0.05),while FBW of pigs in Group ? and ? was not significantly different from that of the Control Group(P > 0.05).Throughout the test period,the ADG of Group III pigs was significantly lower than that of other test group(P < 0.05),and the F/G was significantly higher than that of the Control Group and Group II(P < 0.05).(2)On day 35,the TG and BUN of pigs in Group ? were significantly lower than those of Control Group(P < 0.05).On day 55,the TCH of pigs in Group ? and Group ? wassignificantly lower than that of Control Group(P < 0.05),while the TG in Group ? was significantly increased(P < 0.05).On day 80,the serum biochemical indexes of pigs in all energy-restricted groups returned to normal levels(P > 0.05).On day 35,the Ig A of pigs in Group ? and ? was significantly higher than that of the Control Group(P < 0.05),while the Ig G in Group ? was also significantly increased(P < 0.05).On day 55,the Ig M of pigs in Group ? was significantly higher than that of the Control Group(P <0.05).On day 80,the Ig G of pigs in Group I and Group II was significantly higher than that of Control Group(P < 0.05).On day 35,the GH of pigs in each energy-restricted group showed an increasing trend with the energy-restriction intensity,and the INS and IGF-? showed a decreasing trend,especially in Group ?(P < 0.05).On day 55,the serum GH levels of pigs in each energy-restricted group remained high,especially in Group ?(P < 0.05).And,the INS and IGF-?of pigs in each energy-restricted group returned to normal level(P > 0.05).On day 80,there was no significant difference in Growth Axis hormones of pigs in each test group(P > 0.05)..(3)At the end of the energy-restricted period and the end of the compensatory period,the carcass weight,backfat and eye muscle area of pigs in each energy-restricted group showed a downward trend with the energy-restricted intensity,especially in Group ? pigs(P < 0.05).The leg-hip ratio and lean meat rate showed an increasing trend,especially in Group ?(P> 0.05).At the end of the energy-restricted period,the proportion of CP of Longissimus dorsi in each energy-restricted group increased with the energy-restricted intensity,and the proportion of IMF decreased,and there was a significant difference in pigs in Group II(P < 0.05).At the end of the compensatory period,the CP and IMF of the Longissimus dorsi of pigs in all energy-restricted groups returned to normal levels(P > 0.05),and there was no significant difference in meat quality(P > 0.05).(4)At the end of the energy-restricted period,the expression of IGF-?m RNA in the liver and Longissimus dorsi of pigs in each energy-restricted group showed a decreasing trend with the energy-restricted intensity,and there was a significant difference in pigs in Group ?(P <0.05).At the end of the compensatory period,the expression of IGF-?m RNA in the livers and Longissimus dorsi of pigs in each energy-restriction groups returned to normal levels(P> 0.05).In conclusion,20% energy-restriction in the early growth period(35 kg)of growing pigs and adequate nutritional compensation in the middle and late stages can increase the growth rateand feed utilization rate in the compensation period,then achieve fully compensated growth.It wouldn't adversely affect the serum biochemical indicators,immune indicators and muscle quality,while it reduce the back fat and improve the carcass lean rate. |
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