| This This experiment investigated the effects of different levels of digestible energy and protein in diets on growth performance,apparent digestibility,blood biochemical indices,slaughter performance,and fecal microbiota of Tibetan piglets.A 2×3 factorial completely randomized design was used,with 90 healthy and energetic Tibetan piglets with an initial weight of（6.43±0.92）kg being randomly assigned to 9 treatment groups,with 5 replicates per group and 2 piglets per replicate.The experiment was conducted in two stages:the first stage（6-15 kg）included diets with low(12.55 MJ·kg-1),medium(13.39 MJ·kg-1),and high(14.23 MJ·kg-1)levels of energy,and low（14.50%）,medium（16.50%）,and high（18.50%）levels of crude protein;the second stage（15-30 kg）included diets with low(12.22 MJ·kg-1),medium(13.05 MJ·kg-1),and high(13.89 MJ·kg-1)levels of energy,and low（13.00%）,medium（15.00%）,and high（17.00%）levels of protein.Results showed that:1.Effects of different energy and protein levels on Tibetan piglets（6-15 kg）:The feed-to-gain ratio was significantly lower in the medium and high protein groups compared to the low protein group.Additionally,the average daily weight gain in the low protein group was significantly lower than in the other treatment groups（P<0.05）.Different energy levels significantly affected the apparent digestibility of Tibetan piglets（P<0.05）.The high energy group had significantly higher digestibility of crude fat,crude ash,and total energy compared to the low energy group（P<0.05）.The low energy group had significantly higher digestibility of dry matter compared to the medium and high energy groups,while the medium protein group had significantly higher digestibility of crude ash compared to the other treatment groups（P<0.05）.2.Effects of different energy and protein levels on Tibetan piglets（15-30 kg）:The average daily weight gain was significantly higher in the medium protein group compared to the low and high protein groups,and the high energy group had significantly higher average daily weight gain compared to the low and medium energy groups.When fed a high energy diet,fecal samples from Tibetan piglets showed significantly higher levels of dry matter,crude ash,crude fat,crude protein,and total energy compared to the medium and high energy groups（P<0.05）.When fed a low energy diet,the medium protein group had significantly higher levels of crude fat and crude ash compared to the other treatment groups（P<0.05）.The low protein group had significantly lower levels of total protein（TP）and blood urea nitrogen（BUN）compared to the medium protein and high protein groups（P<0.05）,and the low protein group had significantly higher alkaline phosphatase（ALP）levels compared to the other treatment groups（P<0.05）.The low energy group had significantly higher levels of TP compared to the high energy group（P<0.05）,and the high energy group had significantly lower levels of globulin（GLB）compared to the low energy and medium energy groups.The high energy group also had significantly higher albumin/globulin ratio（A/G）compared to the other treatment groups（P<0.05）.The low energy group had significantly higher BUN levels compared to the medium energy and high energy groups（P<0.05）.The slaughter rate was significantly lower in the low protein group compared to the medium protein and high protein groups,and the medium protein group had significantly higher lean meat percentage,GR value,and backfat ratio compared to the other treatment groups.The low energy group had significantly lower slaughter rate and backfat ratio compared to the medium energy and high energy groups.Organ indices,such as heart,liver,spleen,lung,and kidney,significantly increased with protein intake.3.Effects of different energy and protein levels on fecal microbiota of Tibetan piglets（15-30 kg）:At the phylum level,the Spirochaetes phylum was significantly lower in the medium energy and high energy groups compared to the low energy group（P<0.05）.At the class level,the Clostridia class was significantly lower in the low energy and medium energy groups compared to the high energy group,while the Bacilli class was significantly higher in the low energy and medium energy groups compared to the high energy group.The Spirochaetes class was significantly higher in the low energy group compared to the other treatment groups（P<0.05）.The medium energy group had significantly lower Pielou’s evenness index（P<0.05）,indicating that appropriate energy intake significantly increased the microbial evenness in fecal samples（P<0.05）.The Chao1 index was significantly lower in the high protein group compared to the low protein and medium protein groups,and the Good’s coverage was significantly higher in the high protein group compared to the other treatment groups（P<0.05）.In conclusion,for 6-15 kg housed Tibetan pigs,the appropriate dietary energy level is 14.23 MJ·kg-1and the crude protein level is 16.50%.For 15-30 kg housed Tibetan pigs,the suitable dietary energy level is 13.89 MJ·kg-1,and the crude protein level is 15.00%. |
