Effects of vitamin B6 and tryptophan on pork quality and amount of lean meat in gilts of 70–100 kg bodyweight

Supplementary tryptophan in pig diets has shown improvement in carcass traits and pork quality by reducing the animals' response to stress at slaughter. Vitamin B6 could enhance this response since it acts as an enzymatic cofactor of many tryptophan pathways. The present experiment was designed to evaluate dietary vitamin B6 supplementation and tryptophan levels on carcass traits, organ weights, abdominal fat, and pork quality of 70–100 kg gilts. Sixty-four crossbred gilts (initial bodyweight (BW) 70.52 ± 2.95 kg) were distributed in a 2 x 4 factorial scheme, consisting of two supplementary vitamin B6 levels (1 and 5 mg kg-1) and four dietary standardized ileal digestible (SID) tryptophan (Trp) levels (0.140%, 0.167%, 0.194%, and 0.221%). No significant interactions between the dietary SID Trp levels and B6 supplementation were observed on these variables. Vitamin B6 supplementation (5 mg kg-1) showed a minor reduction in meat pH measured 24 hours after slaughter and resulted in a ham yield higher than B6 basal level (1 mg kg-1). The lean meat yield increased linearly as the SID Trp levels increased in the diet. These findings suggested that vitamin B6 supplementation enhanced the pork quality and the increasing levels of SID tryptophan enhanced the lean meat yield of 70–100 kg gilts.Keywords: Carcass yield, meat colour, organ weigh

Effects of feed particle size on energy values for broiler chickens at various ages

The objective of this study was to evaluate the effects of various geometric mean diameters (GMDs) of particles of corn, pelleted soybean meal and a corn-soy mixture in the proportion of 70% and 30%, respectively, on the nutritional value of the feeds. The study evaluated energy consumption, the contents of apparent metabolizable energy (AME) and AME corrected for nitrogen balance (AMEn) and the metabolizability coefficients for broiler chickens at various ages. A total of 540 Cobb 500 male broilers were housed in metabolic cages (experimental units). Trials were performed separately with each feed. A completely randomized design was used with four treatments, namely corn with 573, 636, 851, and 1012 μm GMDs; pelleted soybean meal with 538, 550, 665, and 741 μm GMDs; and the corn-soy mixture with 627, 658, 893, and 1040 μm GMDs. Birds were evaluated on days 1 - 10, 11 - 20, 21 - 30, and 31 - 40. Larger GMDs resulted in lower energy consumption. From 1 to 10 days, birds consumed less metabolizable energy than older birds. Birds fed corn from days 1 to 10 had higher metabolizable energy (P <0.05) with increasing GMD up to 1042 μm. However, the results varied, depending on the feed and its combinations. The use of coarse particles could reduce the costs of grinding, and would have few effects on the metabolizable energy of broiler chickens

VALORES ENERGÉTICOS DO MILHO E DO FARELO DE SOJA DETERMINADOS COM POEDEIRAS NA FASE DE PRODUÇÃO

The aim of the present research work, carried out with laying hens in the stage of production, was the determination of both apparent metabolic energy (AME) and the nitrogen corrected apparent metabolic energy (AMEn) of the corn and soybean meals. A total of 84 Isabrown birds aging 24 weaks were alloted in a randomized blocks design, using two basal reference diets containing 19 and 14% of CP, respectively. For the experiment, two samples of corn replaced in 25% the reference diet containing 19% of CP, and three samples of soy bean meal replaced in 15% the reference ration containing 14% of CP. It hás been found significant differences in regard to the energetic values and the metabolic coefficients of the reference diets added with soybean meal. In conclusion, it hás been found that the EMA and EMAn values, expressed as kcal/kg as dry matter, for the three samples of soybean meal were 2,292 and 2,537; 2,248 and 1,963; 3,252 and 2,847, respectively, and for the samples of corn, 3,157 and 3,061 and 3,477, respectively.O presente trabalho teve pôr objetivo a determinação, em poedeiras em fase de produção, dos valores de energia metabolizável aparente (EMA) e da (EMAn) corrigida pelo balanço de nitrogênio, do milho e do farelo de soja. Foram utilizadas 84 aves Isabrown com 24 semanas de idade, distribuídas em delineamento experimental de blocos ao acaso, utilizando-se duas rações-referência com 19 e a4% de PB (Proteína Bruta), respectivamente. No experimento levado a efeito, duas amostras de milho substituíram em 25% a ração com 19% de PB e três amostras de farelo de soja substituíram em 15% a ração com 14%  de PB, tendo sido verificada diferença significativa nos valores energéticos e nos coeficientes de metabolizabilidade das  e de amostras de farelo de soja estudadas. Em conclusão, verificou-se que os valores de EMA e EMAn para as três amostras de farelo de soja foram de 2.992, 2.537; 2.248 e de 3.157 e 3.061; e 3.590 e 3.477 kcal/kg de matéria seca, respectivamente, e de 3.157 e 3.061; e 3.590 e 3.477 kcal/kg de matéria seca para as duas amostras de milho, respectivamente