Digestible methionine+cysteine in the diet of commercial layers and its influence on the performance, quality, and amino acid profile of eggs and economic evaluation.

This work aimed at evaluating the effects of 4 digestible Met+Cys levels on the diet of commercial layers and their influence on the productive performance, quality, and amino acid profile of eggs and economic viability of the activity. A total of 576 white Lohmann LSL-Lite layers was distributed into 6 replicates of 24 birds for each diet. The experimental design was completely randomized, with 4 treatments defined by levels evaluated in the feed (0.465, 0.540, 0.581, and 0.647%). The productive performance was measured for 30 weeks. The quality (34 and 50 wk old) and the amino acid profile of eggs (43 wk old) also were evaluated. A linear positive response was observed at higher Met+Cys levels for feed intake, number of eggs per housed bird, and digestible Met+Cys intake. Egg production, egg weight, egg mass, feed efficiency, and weight gain had their optimal values determined by the quadratic regression model at 0.638, 0.654, 0.647, 0.644, and 0.613% digestible Met+Cys, respectively. In the 34th wk, eggshell thickness decreased linearly at higher Met+Cys levels. In the 50th week, the optimal levels detected for eggshell thickness and percentage were 0.571 and 0.570% digestible Met+Cys, respectively. The percentages of proteins, branched-chain amino acids (leucine, isoleucine, and valine), histidine, and proline in eggs (albumen+yolk) showed a linear negative response in function of higher Met+Cys levels. Higher digestible Met+Cys levels (>0.630%) led to a good performance of layers, while lower Met+Cys levels improved the eggshell quality of layers in peak production. Optimal Met+Cys levels may change according to the price of the synthetic amino acid.

DNA hypomethylation and proliferative activity are increased in the rectal mucosa of patients with long-standing ulcerative colitis.

BACKGROUND: DNA methylation and DNA cytometric parameters were evaluated in the rectal mucosa from patients with extensive and long-standing ulcerative colitis. METHODS: Twenty-six patients with extensive disease for more than 7 years and 11 healthy controls were included. Global DNA methylation was assessed as the capacity of the DNA test to incorporate [3H]methyl groups from [3H]-S-adenosyl-methionine in the presence of Sss1 methylase. A higher incorporation reflects a lower state of intrinsic methylation. DNA ploidy, S-phase fraction, and proliferative index (PI = S + G2M) of the cell cycle were analyzed by flow cytometry. RESULTS: Incorporation of the [3H]methyl groups into DNA was 10-fold higher in patients compared with controls (P < 0.001) and was significantly higher in patients with histologically active disease (P = 0.02). With regard to flow cytometry, all samples showed a diploid pattern, but S-phase fraction and the proliferative index values were significantly increased in patients compared with controls (P = 0.0007 and P = 0.003, respectively). A positive correlation was found between S-phase fraction and proliferative index and the number of exacerbations of the disease (P < 0.005), and there was a trend among those patients who had disease for longer than 20 years to present with increased cellular proliferation compared with those with a shorter evolution of disease (P > 0.05). CONCLUSIONS: DNA hypomethylation and proliferative activity are increased in this group of patients, supporting the concept that their colonic mucosa undergoes epigenetic and kinetic changes that might predispose these individuals to develop colorectal neoplasms. However, it cannot be ruled out that these markers solely reflect hyperproliferation associated with active inflammation.