RESUMO
This work was developed to evaluate the impact of the addition of proteases on the performance characteristics, egg quality, relative weight of digestive organs, and intestinal morphometry of laying hens. 390 Hy Line W36® hens were allocated into five treatments and six replicates with 13 animals. The treatments were: 1) Control (standard formulation), 2) Negative control A - NCA (nutritional reduction according to protease A matrix), 3) Negative control B - NCB (nutritional reduction according to protease B matrix), 4) NCA+protease A (0.250 g/kg of feed) and 5) NCB+protease B (0.125 g/kg of feed). Hens fed the NCA, NCB, and NCA+protease A diets showed reductions in feed intake and egg mass. The addition of protease B provided better results for egg production in both percentage and per dozen as compared to the group fed with the NCA+protease A diets. The hens subjected to diets NCA and NCB showed eggs with a reduced eggshell and thickness percentage. However, supplementation with proteases A and B improved these parameters to values similar to the controls. There was no significant effect of the treatments on the relative weight of the liver, proventricle, gizzard, pancreas, and small intestine. However, the addition of protease A resulted in a decreased value for the relative weight of the large intestine. The jejunum and ileum crypt depths were, respectively, smaller in hens fed the control diet in relation to the NCB diet and the NCA and NCB diets. As it can be concluded, Protease B supplementation provided the best performance results.(AU)
Assuntos
Animais , Peptídeo Hidrolases/fisiologia , Galinhas/fisiologia , Ingestão de Alimentos/fisiologiaRESUMO
Chicken feet have become an important commodity in the international market, representing a significant portion of poultry products exported by countries such as Brazil and the USA. However, the presence of pododermatitis in the footpad is an important barrier to exportation, since importing countries do not accept injured feet or allow the use of automatic equipments to remove the affected tissue. The objective of this research was to evaluate the impact of using an automatic equipment to remove injuries of pododermatitis on histological and microbiological traits of broiler feet processed according to commercial practices. A total of 240 broiler feet obtained from a commercial processing plant was visually classified according to the degree of pododermatitis and distributed in a 4 × 2 factorial arrangement, totalizing eight treatments with 30 replications. Factors were feet classification (1 to 4) and injury removal (yes or no). Feet were sampled for microbiological and histological analysis before and after the mechanical removal of pododermatitis injuries by an automatic machine that promoted footpad epidermal scarification. No significant interaction between feet classification and injury removal was detected for any of the analyzed variables. Also, no significant effect of feet classification was detected on aerobic plate counts, total coliforms and Escherichia coli. Feet inflammation score tended to increase (P = 0.06) according to the downgrading of feet classification, but the mechanical removal of pododermatitis injuries reduced feet inflammation score (P < 0.01), total coliform counts (P = 0.01), and E. coli (P = 0.01) independently of feet classification. Together, these results demonstrate the efficacy of the automatic equipment in removing both the inflammatory tissue and its associated microbiota in broiler feet affected by pododermatitis. Therefore, in addition to the already authorized use of blades, the use of automatic equipments for epidermal scarification in the processing of broiler feet deserves further consideration by the regulatory agencies.