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

Effect of the reduction of the crude protein content of diets supplemented with essential amino acids on the performance of piglets weighing 6-15kg

Two experiments were conducted to assess the effect of the reduction of the crude protein (CP) content of diets supplemented with amino acids on piglets weighing 6-15. kg. In the performance experiment (Experiment I), 120 piglets weaned at 21 days of age with initial live weights of 5.95±0.33. kg were distributed into five treatment groups. This grouping followed a randomized block design with eight repetitions and three animals per experimental unit. The treatments consisted of five different diets, in which the CP content were reduced from 21.0% to 15.0% (21.0%, 19.5%, 18.0%, 16.5%, and 15.0% CP); the amino acid requirements of the diet were met by adding L-lysine, DL-methionine, L-threonine, L-tryptophan, L-valine, and L-isoleucine. No differences were found in the variables associated with performance among animals from different treatment groups. Therefore, any of the investigated CP levels can effectively be used in piglet diets supplemented with synthetic amino acids. The essential/nonessential amino acid ratio (EAA:NEAA) increased with the reduction of the CP content, and the best ratio (53:47) was achieved with the diet containing 15% protein. Urea concentrations decreased linearly with protein reduction (Experiment I). To assess the nitrogen balance (Experiment II), 20 crossbred male castrated piglets from a commercial lineage, weaned at 21 days of age, were randomly assigned in two blocks, in which each block had two replicates (four replicates per treatment). The average live weight of the piglets was 10.79±2.19. kg. The animals were housed in metal cages and were distributed into five treatment groups following a randomized block design with four repetitions; the experimental unit consisted of one piglet. The nitrogen excretion and blood and urine urea concentrations decreased linearly (. P < 0.05) with the reduction of CP in the diets, resulting in reduced nitrogen excretion into the environment. © 2014 Elsevier B.V