Effect Of Different Protein Source Diets On Digestion And Absorption Of Crude Protein In Weaned Piglets

Dietary protein resources are closely related to the diet digestion, absorption, and theefficiency of dietary nitrogen.This study used the single factor randomized design. Thirty-sixcrossbred barrows from the same source and with the similar age and similar weight arerandomly divided into3groups, each group has12piglets, and all piglets are fed individually insingle metabolic cage. Three dietary treatments are as follows: corn-soybean diet with17%protein as control group (COS), casein group (CAS), and corn DDGS group (DDGS). Amongthe three groups,5%of crude protein from soybean of COS diet was replaced by casein orDDGS. The experiment contained a7-day pre-feeding period and a28-day feeding period. Theresults are as follows:Firstly, the effects of dietary protein source on growth performance and rates of diarrhea inweaned piglets were different. Compared with DDGS group, there were significant differenceson final body weight (FBW)(P <0.01), average daily gain (ADG)(P <0.01), average dailyfeed intake (ADFI)(P <0.05), and feed gain ratio (F/G)(P <0.05) between COS group andCAS group. There were no significant differences (P＞0.05) on growth performance betweenCOS group and CAS group. The rate of diarrhea in CAS group was significant lower thanDDGS group and COS group (P<0.01), while no difference in the diarrhea rate was observedbetween COS group and DDGS group (P＞0.05).Secondly, the effects of dietary protein source on apparent disgestibilities of nutrients andN utilization in weaned piglets were different. No significant effects on the apparent digestibilityof fat and crude fiber were observed among three groups (P＞0.05). Apparent digestibility ofdry matter and crude protein are the highest in CAS group compared to the other two groups,which reached86.45%(P <0.01) and82.97%(P <0.01). There were significant differences inthe amount of nitrogen excreted in feces, total nitrogen excretion, nitrogen digestibility, andnitrogen utilization between DDGS groups and CAS group (P<0.05), while the nitrogenutilization of CAS group was the highest, reaching69.03%.Thirdly, the effects of dietary protein source on the total free AA in gastrointestinal andserum of weaned piglets were different. The total free AA of CAS was faster in the duodenum toreach the highest levels (P<0.05), and then gradually reduced; the total free AA of COSgradually increased, the content of the highest end of the jejunum (P<0.01), and then decreased;the total free AA of was the lowest levels in the duodenum, and then elevated levels peaked atthe end of the jejunum, and then decreased rapidly. In the back-at the cecum, the total free AA of DDGS group than the other two groups (P<0.05).The effects of dietary protein sources onblood levels of free Val (P<0.01),Arg (P<0.05), the other free AA (P＞0.05). The levels of EAA,NEAA, and total AA were higher than the COS and DDGS groups in serum.Fourthly, the effects of dietary protein source on serum biochemical parameters of weanedpiglets were different (P＞0.05), but the total of protein (TP) and globulin (GLB) of CAS groupwere higher than the content of DDGS and COS groups; the content of urea nitrogen (UREA) ofCAS group was lower than DDGS group,15.23%(P<0.05).Comprehensive this research shows that: it was consistent on production performance,digestion and absorption of crude protein and the effects of nitrogen utilization of the three diets.If you don’t consider economic factors, the effect of casein is best as pigs fed diets, and has thehighest nitrogen utilization, so it is the best choice for this experiment.