Evaluation And Prediction Model Of Nutritional Value Of Cassava Fed To Growing-finishing Pigs

This study aimed to evaluate the nutritional value of cassava for growing and finishing pigs and the prediction equations of cassava digestion energy(DE),metabolic energy(ME)and standardized ileal digestibility(SID)based on its nutritional components.The experiment was divided into two parts.(Experiment 1)Preparation of effective energy test tiet with 10 different sources of cassava,the growing-finishing pigs were taken as the experimental objects,and the digestion energy and metabolic energy of cassava were determined by digestion and metabolism test and the feces and urine of pigs were collected.The prediction equations of digestion energy and metabolic energy of cassava were established based on its nutritional components.(Experiment 2)Test diet for amino acid digestibility of cassava from 10 different sources,The growing-finishing pigs were taken as the experimental objects,and the apparent ileal digestibility(AID)and SID of cassava ileum were determined by digestion and metabolism test and the ileal chyme of pigs was collected.Based on its nutritional components,the standard amino acid digestibility of cassava essential amino acids was established,and the nutritional parameters of cassava were established,which provided a theoretical basis for feed production.Experiment 1 Evaluation and Prediction Model of Digestible Energy and Metabolic Energy of Cassava Fed to Growing-finishing PigsThis study was to determine the nutritional composition and DE and ME of cassava fed to growing-finishing pigs and to develop prediction models for DE and ME of cassava based on its effective chemical composition.Twenty-two healthy[Duroc×(Landrance×Yorkshire)]barrows with initial weight of(50 0±1.7)kg were randomly selected and assigned to a basal diet and 10 cassava diets according to a replicated incomplete Latin square design of 11×3,respectively,The experiment was divided into 3 cycles,12 days per cycle(d)(7 d pre-feeding period+5 d fecal collection)and 6 replicates per diet treatment group at the end of the experiment.The DE and ME values of growing-finishing pigs were measured by total fecal and urine collection and difference method.The DE and ME prediction equation of cassava fed to growing-finishing pigs based on its effective chemical composition was established via stepwise regression method.The results showed that the variation ranges of grass energy(GE)and the contents of crude protein(CP),drymatter(DM),ash(Ash),ether extract(EE),calcium(CF),neutral detergent fiber(NDF)and acid detergent diber(ADF),total starch(TS)of 10 cassava samples under air-dry basis were 1.56 to 15.36MJ/kg,1.76%to 3.51%,86.10%to 88.66%,1.99 to 2.53%,0.37%to 1.98%,0.08%to0.12%,0.06%to 0.11%,1.26%to 3.00%,7.82%to 17.47%,1.50%to 5.32%,58.75%to 69.86%,respectively.The average DE and ME values for 10 cassavas were(13.52±0.68)MJ/kg and(13.25±0.67)MJ/kg under air-dry basis,respectively.The possible DE and ME recommended prediction equations(air-dry basis)of cassava were DE=54.591-3.279GE+0.680CP+2.822Ash(R~2=0.80)and ME=0.108+0.972DE(R~2=0.98),respectively.Experiment 2 Evaluation and Prediction Model of Amino Acid Digestibility of Cassava Fed to Growing-finishing PigsThis experiment was conducted to determine the AID and SID of amino acids of cassava for growing-finishing pigs,and to develop prediction model for SID of amino acids of cassava based on its conventional nutrient contents.Twenty-two healthy Duroc×Landrance×Yorkshire ileal-cannulated pigs with the body weight of(36.0±1.4)kg were randomly selected and assigned to 10 cassava diets and a nitrogen-free diet according to a replicated incomplete Latin square design of 11×3.The results showed that,on the air-dry basis,the contents of lysine(Lys),methionine(Met),threonine(Thr),tryptophan(Trp)in cassava were 0.09%to 0.24%,0.01%to 0.03%,0.05%to0.11%,0.04%to 0.07%.Among the cassavas from ten producing areas,most of amino acids in the cassavas from Yulin and Laibing of Guangxi had higher content.The AIDLys,AIDMet,AIDThr,AIDTrp of cassava for growing-finishing pigs were54.21%to 87.96%,41.33%to 84.95%,31.67%to 73.14%,74.40%to 91.12%,respectively,and The SIDLys,SIDMet,SIDThr,SIDTrp were 69.20%to 95.53%,69.62%to 97.81%,73.04%to 95.44%,84.50%to 96.20%.The prediction models for SIDTrp,SIDArg,SIDLeu,SIDVal and SIDPhe in cassava for growing-finishing pigs were established in this experiment,and the key predicting factors included CP、Ash、DM and NDFIn summary,the average DE and ME of cassava samples for growing-finishing pigs were(13.52±0.68)MJ/kg and(13.25±0.67)MJ/kg,respectively.The amino acid digestibility of growing-finishing pigs for cassava(air-dried basis)was higher,the AID was mostly between 60%and 80%,and the SID was mostly between80%and 90%.Cassava has high effective energy,ileal amino acid digestibility and good nutritional value for growing and fattening pigs.