Effects Of Dietary Protein Sources On Egg Quality And Its Mechanism Under Ideal Protein Mode

The experimental diets were formulated on the based isocaloric(ME, 11.11MJ/kg),isonitrogenic(CP,16.5%) and on the equal digestible amino acid profile. To evaluate the effect of dietary protein sources(i.e. soybean meal,SBM; cottonseed protein,LCSM; double-zero rapeseed meal,DRM) on performance and egg quality during peak production of laying hens were tested firstly. And then to evaluate to the effects of dietary protein sources on egg quality during storage were studied. Further,the proteomic analysis of egg white protein under refrigeration to explain the effect of dietary protein sources on egg quality metabolism.Experiment 1 was conducted to investigate the effect of dietary protein sources on egg production and egg quality of laying hens. Four hundred and thirty-two laying birds of 32 weeks of age were allotted into 6 treatments groups with 6 replicates of 12 birds each. The control group was fed corn-soybean meal basal diet,and 5 of the experiment diets included 100 g/kg LCSM,187g/kg LCSM,148.7 g/kg DRM,292 g/kg DRM,99.2 g/kg LCSM and 135.2 g/kg DRM,respectively(correspondingly,50%(LCSM50),100%(LCSM100), 50%(DRM50),100%(DRM100),50%LCSM and 50%DRM(LCSM50-DRM50) dietary protein content provided by SBM in the control were replaced by LCSM or DRM,respectively). The feeding trial lasted for 12 wks. After 12 wk of diet feeding,a total of 586 eggs as collected for egg quality determination during storagement. Egg from six dietary protein sources(SBM,LCSM50,LCSM100,DRM50,DRM100,and LCSM50-DRM50)were used. A total of 216 eggs were stored at 4℃ or 28℃ for 28 d,respectively. And then to ditermined egg quality at 0 d and 28 d,respectively. The other 270 eggs were stored at 4℃,and ditermined egg quality at 0 d,14 d,28 d.The results showed as follows:(1) feeding LCSM100 diet significantly reduced daily egg mass(P<0.05) in comparison with SBM diet feeding during wks 7-12. LCSM50 and DRM50did not negatively affect egg performance as compared to the SBM group during overall period of the trial.(2) The LCSM50 group deepened the yolk color at the end of 12 wks(P<0.05) compared to the SBM group.(3) The dietary protein sources could remarkable influences plasma TP(P=0.02),ALB(P=0.04),and GLB(P=0.03) at the end of 12 w. Lower TP was observed in the LCSM100 group than the SBM group(P<0.05).(4)LCSM100and LCSM50-DRM50 diet decreased albumen weight(P<0.05) and eggshell-free weight(P<0.05) compared to SBM diet, while lower CP weight in albumen(P<0.05) and lower CP weight in whole egg(P<0.05) were observed in LCSM100andLCSM50-DRM50 group compared to the SBM group at the end of 12 wks.(5) The LCSM100 diet resulted in higher yolk hardness compared to other diets when eggs were stored at 4℃ for 28 d(P<0.05). Lower HU were observed in the DRM100 and DRM50 groups than other groups when eggs were stored 28 d at 4℃.(6) Lower egg quality were observed in the DRM100 diet than other groups when stored for 28 d at 28 ℃(P<0.05), while there were no differencesin egg internal quality among the other groups. Yolk breakage occurred was observed in the DRM100 group and eggs could not be analysed for egg internal quality when stored at 28℃for 28 d.(7)The egg Haugh units(HU) in the LCSM100,DRM50 and DRM100 groups were significantly lower than those in the SBM and LCSM50 groups were stored to 4 wk at 4℃. The hardness and springiness of the cooked yolk in the LCSM100 group were significantly higher than those in the other treatment groups.(8) A lower HU were observed in the DRM100 group compared to the SBM and LCSM50 groups when the eggs were stored to 4 wk at 4℃,and the yolk hardness was higher in the LCSM100 group compared to the other group(P<0.05).Based on this study,it is concluded that LCSM100 and DRM100as sole protein ingredient may negatively affect egg performance and egg quality after feeding for more than 6 weeks, and LCSM100 as sole protein ingredient may negatively affect protein deposition in body and protein deposition in albumen with feeding consecutive 12 weeks. Whereas LCSM50 or DRM50 can still get satisfied egg performance and quality within feeding consecutive 12 weeks, and LCSM50 or DRM50 can still get satisfied protein metabolism of body and egg composition within feeding consecutive 12 weeks during the peak production of laying hens. LCSM100 or DRM100as sole dietary protein source for laying hens may adversely affect the internal quality of stored eggs than SBM diet, and LCSM50 may maintain similar egg quality to SBM diet for eggs stored under refrigerated condition.Experiment 2 was conducted to investigate the effects of dietary protein sources on body health of laying hens andalbumen expression. Two hundred and sixteen laying birds of 32 weeks of age were allotted into 3 treatments groups with 6 replicates of 12 birds each. The control group was fed corn-soybean meal basal diet,and 2 of the experiment diets included 195g/kg LCSM and292 g/kg DRM,respectively(correspondingly,100%(LCSM100),100%(DRM100) dietary protein content provided by SBM in the control were replaced by LCSM or DRM, respectively). The feeding trial lasted for 12 wks. At the end of 12 w, and then calculate the organ index, the morphological and pathological changes of jejunum were collected in the jejunum,liver,kidney and magnum.After 12 wk of diet feeding, a total of 72 eggs as collected for egg quality determination. The 54 eggs samples were stored in the cool room of a refrigerator(4℃),and the then determinate egg quality. The other 18 eggs samples was carried out to i TRAQ techniques reveal dietary protein sources response mechanisms of egg albumen after storated 28 d at 4℃.The results showed as follows:1) The oviduct index in the LCSM100 group was significantly lower than that in the SBM group(P<0.05),a lower abdominal fat rate and lower liver fat ratewere observed in the DRM100 group compared to the SBM group(P<0.05). 2) The mucosal columnar epithelial cell layer of magnum in LCSM100 group was incomplete, mild swelling of tubular glands,mainly fold almost can not see gland secretions. The villous height of jejunum in LCSM100 group was significantly lower than that in the other treatments(P<0.05). 3)The ovomucin content in LCSM100 group and DRM100 group were lower than that in the SBM group(P<0.05)when stored for 28 d at 4℃. 4) We identified 106 protein groups in albumen after storedfor 28 dat4 ℃ using the high-throughput, i TRAQ. Compared to SBM group, the analysis manifest 6differentially expressed proteins were identified in LCSM100 group, of which 6 differentially expressed proteins were up-regulated. And compared to SBM group, the analysis manifest 12 differentially expressed proteins were identified in DRM100 group, of which 5 differentially expressed proteins were up-regulated, 7 differentially expressed proteins were down-regulated.These differentially expressed proteins, which were mainly involved in carbon metabolim,biosynthesis of amino acids and glycolysis/gluconeogenesis.It wasconcluded that LCSM100 as sole protein source in laying hens diets on the jejunum absorption ability and magnum secretory capacity have a negative impact.The ovomucin weight in LCSM100 group and DRM100 group were lower than that in SBM group when storage 4 w at 4 ℃. The nagative effects of LCSM100 and DRM100 on egg quality may be due to regulation of protein expression.In summary, it wasconcluded that LCSM100 or DRM100 as sole protein ingredient may negatively affect egg performanceand egg quality during peaking production of laying hens.LCSM100 could reduced jejunum villus height,oviduct index and negative affect on yolk hardness,while DRM100 reduces albumen quality during storage. Dietary protein sources affect carbon metabolism,amino acid metabolism and glycolysis/gluconeogenesis.