Effect of chromium-methionine supplementation on meat quality of broilers reared under heat stress / [Efeito da suplementação de cromo-metionina na qualidade da carne de frangos de corte criados em estresse por calor]

Objetivou-se avaliar o efeito da suplementação de cromo-metionina em dietas para frangos de corte criados em estresse por calor, no período de 22 a 43 dias de idade, nos parâmetros de qualidade da carne. Foram utilizados 336 frangos de corte, machos, da linhagem Cobb 500, com 21 dias de idade, distribuídos em delineamento em blocos inteiramente ao acaso, com quatro blocos (cada câmara climática), seis tratamentos (0; 0,10; 0,20; 0,40; 0,80 e 1,20mgkg-1 de Cr na forma de Cr-metionina), oito repetições e sete aves por unidade experimental. Aos 43 dias de idade, duas aves por unidade experimental foram selecionadas e abatidas para avaliação da qualidade da carne de peito, por meio dos parâmetros de pH15min, pH24h, luminosidade (L*), teor de vermelho (a*), teor de amarelo (b*), croma (C*), ângulo hue (Hº), capacidade de retenção de água, perda de peso por cozimento e força de cisalhamento. Houve efeito quadrático (P=0,0070) na capacidade de retenção de água da carne de peito. A suplementação de CrMet não afetou (P>0,05) os demais parâmetros de qualidade da carne. Assim, recomenda-se a suplementação de 0,59mgkg-1 de CrMet para frangos de corte para melhoria da capacidade de retenção de água do peito.(AU)

Zinc, manganese, and copper amino acid complexes improve performance and bone characteristics of layer-type chicks under thermoneutral and cold stress conditions.

Two experiments were designed to evaluate the effect of mineral-amino acid complexes (AACM) as a partial replacement of inorganic mineral (IM) in layer-type chicks' diets. Both studies had the same dietary treatments, where in experiment 1 (Exp. 1) was conducted under thermoneutral conditions from 0 to 35 D and chicks in experiment 2 (Exp. 2) were exposed to cold stress conditions at nighttime during the first 15 D and to thermoneutral condition from 16 to 35 D. For each trial, 1,200 one-day-old Lohmann Brown chicks were used, with 20 cage replicates with 30 chicks per cage. Treatments consisted of the control diet (IM; with 70, 70, and 8 mg/kg of zinc [Zn], manganese [Mn], and copper [Cu], respectively) and the treatment diet (AACM, with 40, 40, and 2.75 mg/kg of Zn, Mn, and Cu, respectively, from IM sources, along with 30, 30, and 5.25 mg/kg of Zn, Mn, and Cu, respectively). Data were submitted to analysis of variance, and means were compared using the t-test (P < 0.05). In Exp. 1, there were no significant differences between treatments on chick performance. However, AACM-fed chicks had higher thymus (P = 0.03) and cecum weight (P < 0.01), superior micromineral deposition in the tibias (P < 0.01), and reduced phosphorus excretion (P = 0.03). In Exp. 2, chicks fed with AACM had higher body weight gain (P = 0.04), better average daily feed intake (P = 0.03), lower phosphorus excretion (P = 0.02), and higher liver and pancreas weight (P < 0.01) in the last week of the study. In conclusion, chicks fed with AACM under thermoneutral conditions had higher bone mineralization and reduced excretion of phosphorus, and in adverse conditions, AACM improves performance and liver and pancreas weight, also reducing phosphorus excretion.

Broiler responses to increasing selenium supplementation using Zn-L-selenomethionine with special attention to breast myopathies.

A study was conducted to evaluate growth performance, carcass and breast yields, and the occurrence and severity of white striping (WS) and wooden breast (WB) myopathies of broilers fed diets supplemented with increasing dietary levels of an organic source of selenium (Zn-L-SeMet). Broilers were fed 6 treatments with 12 replications of 26 birds in a 4-phase feeding program from 1 to 42 days. Corn-soy-based diets were supplemented with 0, 0.2, 0.4, 0.6, 0.8, and 1.0 ppm of Zn-L-SeMet. At 42 d, 6 birds were randomly selected from each pen (n = 72) and processed for carcass and breast yields. Breast fillets were scored for WS and WB at 42 days. Increasing Zn-L-SeMet led to quadratic responses (P < 0.05) for FCR from 1 to 7 d, BWG from 22 to 35 d, and for both responses from 8 to 21 d and 36 to 42 d, as well as in the overall period of 42 days. Carcass and breast yields presented a quadratic improvement (P < 0.01) with increasing Zn-L-SeMet supplementation and Se requirements were estimated at 0.85 and 0.86 ppm, respectively. In the overall period, estimates of Se requirements were 0.64 ppm for BWG and 0.67 ppm for FCR. White striping and WB scores presented quadratic increases (P < 0.01), and maximum scores were observed at 0.68 and 0.67 ppm, respectively. Broilers fed diets formulated without Se supplementation had a higher percentage of normal fillets compared to other Se supplementation levels (quadratic, P < 0.05). In conclusion, increasing Se supplementation to reach maximum growth performance led to higher degrees of severity of WS and WB. Selenium requirements determined in the present study were significantly higher than the present commercial recommendations.