Effect of supplementing papaya (Carica papaya) latex on performance, carcass traits and nutrient digestibility in broiler chicken fed recommended and sub-optimal levels of dietary protein

Abstract

Three experiments were conducted to study the effects of supplementing papaya (Carica papaya) latex (papain) (PL) on performance, carcass variables and apparent ileal digestibility of nitrogen and energy in broiler male chickens (Vencobb 430) fed diets containing varying levels of protein. The PL (4000 TU g􀀀 1) was supplemented to maize-soybean meal based control diet (CD) to provide four concentrations of papain (0, 600, 800 and 1000 TU kg􀀀 1 diet) in experiment 1. In experiment 2, the CD (100% protein) and a low-protein basal diet (95% less protein i.e. about 1% of diet and proportionate limiting amino acids concentration) were fed with and without PL (0 and 1000 tyrosine units - TU kg􀀀 1 diet) in a 2 × 2 factorial design. Three graded levels of dietary protein (88%, 94% and 100% of the recommended level) with three concentrations of PL (0, 1000 and 2000 TU kg􀀀 1) were fed in experiment 3 to find the possibility of reducing dietary protein with higher concentrations of papain in the diet. Each diet was fed ad libitum to 10 replicates of 25 broiler chicks in each replicate (6.5 ×4 feet floor pen) from d 1–35. In experiment 1, supplementation of papain at 1000 TU kg􀀀 1 to the CD significantly improved the feed efficiency (FE) compared to the control group (1–35d). In experiment 2, by reducing the dietary protein by 1%, the body weight gain (BWG) and FE reduced (1–35 d). However, supplementation of 1000 TU papain significantly improved the BWG and FE, which were similar to the control. The interaction between dietary protein and PL did not influence the performance variables in experiment 3, except the FE during 1–21 d. At 88% protein, PL supplementation significantly improved the FE and such improvement was not observed at 94% and 100% protein during d 1–21. Supplementation of 2000 TU papain / kg improved FE similar to those fed the CD, which implies the possibility of reducing the dietary protein with papain supplementation. BWG and FE improved significantly with papain at 2000 TU kg􀀀 1 diet compared to the CD. An increase in dietary protein progressively reduced the relative weights of abdominal fat and liver. Papain supplementation reduced the ready to cook yield and breast weight. Papain supplementation significantly increased the digestibility of energy and nitrogen compared to the control group. Based on theresults, it is concluded that papain supplementation (1000–2000 TU kg􀀀 1) in the form of papaya latex could able to reduce the requirement of protein (about 95% of the recommendation) in corn soybean meal based diets without affecting the performance. Increased digestibility of energy and protein with papain might be responsible for the reduced requirement of protein as observed in the current study.