Effects Of Dietary Leucine Supplementation On Corp Protein Synthesis Of Pigeon And Pigeon (Columba Livia) Growth Of Squabs

In order to determine the effects of leucine(Leu)levels in diets on the synthesis of pigeon milk protein and the growth of squabs,different levels of leucine were added to low-protein diets.In this experiment,240 pairs of pigeons(Columba Livia)with similar weights and reproductive cycles were selected and randomly divided into 5 treatments,each treatment with 6 replicates,each replicate with 8 pairs of pigeons.The experiment adopted "2 + 4" feeding mode.Treatment 1 was supplied high protein diet(CP = 18%,positive control,PC group),treatment 2 was supplied low protein diet(CP = 16%,negative control,NC group),treatment 3 ~ 5 were supplied the diets were respectively supplemented with 0.15%,0.45% and 1.05% leucine in NC group.The diets of treatment 1 and treatment 2 had the same leucine content.The test period was divided into two stages: incubation period and feeding period.The weight and average daily feed intake of the pigeons were determined during the test period,and the average daily gain of the squabs was determined during the feeding period;on the third day of the breeding period,one pair of pigeon was randomly slaughtered from each repetition.The crop tissue was harvested to measure the relative weight and thickness.H&E staining was used to observe the structure and morphology of the crop tissue.Western blotting and immunohistochemistry techniques were used to determine the expression of the target of rapamycin(TOR)signaling pathway protein in the crop tissue.Squabs were slaughtered to determine slaughter performance when they were 21 days old.The results shown:(1)Compared with the negative control group,feeding a breeder with a low protein diet supplemented with 0.45% Leu or feeding a high protein diet can significantly reduce the weight loss of the breeding pigeons during the incubation period and the feeding period(P < 0.05);Adding 0.45% or 1.05% Leu to the low-protein diet significantly increased the thickness and relative weight of the pigeons’ crop tissue(P < 0.05).(2)Compared with the negative control group,adding 0.15% or 0.45% Leu to the pigeons diet can significantly increase the squabs’ average daily gain(P < 0.05);Adding 0.45% Leu to the low-protein diet significantly increased the squans’ eviscerated yield and breast muscle rate(P < 0.05),and reached the level of the high-protein diet group.(3)The results of Western blotting and immunohistochemistry showed that the addition of 0.15% or 0.45% Leu in low protein diets significantly increased the relative expression of TOR signaling pathway-related proteins in the crop tissue of pigeons(P < 0.05).In summary,adding leucine to the diet may activate protein expression in the TOR signaling pathway in the crop tissue,thereby promoting crop protein synthesis and squabs growth.Therefore,1.75% is recommended that the optimal level of leucine in the low-protein diet(CP = 16%)during the incubation period and the feeding period.