Effect of nutrient density on production performance, egg quality and humoral immune response of brown laying (Dahlem Red) hens in the tropics

A study was conducted to evaluate the effect of various concentrations of metabolizable energy (ME) with graded incremental levels of crude protein (CP) and essential amino acids (lysine and methionine) on production performance, egg quality and humoral immune response of Dahlem Red laying hens. Four experimental diets based on maize-soybean meal-deoiled rice bran were prepared. Diet 1 was fed as a control diet containing 2,600 kcal ME/kg, 15% CP, 0.75% Lys and 0.36% Met, and in the other three diets (D2, D3 and D4), concentrations of the above nutrients were increased by 2.5%, 5.0% and 7.5%, respectively. The levels of Ca (3.5%) and available P (0.32) were constant in all the diets. Each diet was offered ad libitum from 28 to 40 weeks of age to eight replicates containing six birds in each replicate. The egg production, egg weight and egg mass (in grams of egg per hen per day) were not affected by increasing the nutrient density up to 7.5% (2,795 kcal ME/kg diet) compared to the control group (2,600 ME/kg diet). However, feed consumption and feed efficiency (in grams of egg per gram of feed) were influenced by the variation in the nutrient density of diets. As the nutrient density increased by 5% (2,730 ME/kg diet), birds consumed significantly (P < 0.001) less feed. The birds in the 7.5% higher density group produced significantly (P < 0.05) higher egg mass per unit feed consumption compared to the control diet. Increasing nutrient density up to 7.5% had no effect on relative weight of albumen, yolk or shell. The Haugh unit, yolk colour and shell thickness were also not affected due to variation in the nutrient density. The humoral immune response measured at 34 and 40 weeks was progressively improved by increasing the nutrient density up to 5%. Increasing the nutrient density beyond 5% in the diet had no further influence on the humoral immune response. Based on the results of the present study, it can be concluded that Dahlem Red laying hens required 2,795 kcal/kg ME, 16% CP, 0.8% lysine and 0.4% methionine for eliciting optimum performance and immune response during 28 to 40 weeks of age.

Níveis de metionina + cistina digestíveis em rações para poedeiras no pico de produção

Avaliaram-se os efeitos de níveis de aminoácidos sulfurados digestíveis (AASD) sobre o desempenho e a qualidade interna e externa de ovos de 360 poedeiras de 25 a 41 semanas de idade. Foram formuladas seis dietas experimentais: cinco continham 0,578; 0,636; 0,694; 0,752 ou 0,810% de AASD, e em uma o nível de AASD foi o usualmente recomendado, cada tratamento com cinco repetições de 12 aves, em quatro períodos de avaliação de 28 dias cada. Melhores resultados para produção de ovos, conversão alimentar, massa de ovos e ovos viáveis foram obtidos com as aves que consumiram 729; 751; 801 e 730mg AASD/dia, respectivamente. A elevação dos níveis de AASD resultou em aumentos lineares no consumo de ração, no ganho de peso, nas porcentagens de gema e no extrato etéreo na gema. Nos ovos armazenados por sete dias, houve aumento linear da porcentagem de gema e decréscimo linear da porcentagem de casca, unidade Haugh e peso específico com a elevação dos níveis de AASD. Conclui-se que, para melhores produção e qualidade interna e externa de ovos, é necessário o consumo de 752mg de AASD ou de 864mg de aminoácidos sulfurados totais por ave/dia.

The Combined Effects of Dietary Lysine and Total Sulfur Amino Acid Level on Egg Production Parameters and Egg Components in Dekalb Delta Laying Hens

Dekalb Delta hens were randomly assigned to one of eight dietary treatment groups. Two intakes of lysine (860 and 959 mg/hen per day) and 4 intakes of TSAA (635, 689, 811, 877 mg/hen per day) were combined in a 2 x 4 factorial treatment arrangement and fed from 20 to 43 wks of age. A phase feeding regimen was implemented at 43 wk with lysine intake lowered to 715 or 816 mg/hen per day and TSAA to 578, 607, 699, or 779 mg/hen per day. Cage was the experimental unit (5 hens/cage), and dietary treatments were replicated 8 times. Egg production (EP) and feed consumption were not affected by dietary treatments. Feed efficiency improved linearly by increasing TSAA intake during phase I only. Hen weight gain was improved (P < or = 0.03) by increased dietary lysine (94.2 vs. 135.2 g weight gain/hen). During phase I, hen weight gain was affected quadratically (P < or = 0.02) by TSAA. Increasing TSAA intake up to 689 mg/hen per day increased hen weight gain, but gain decreased at the highest intake. Egg weights (EW) increased (P < or = 0.02) from 59.02 to 60.21 g with increased lysine intake. Increasing lysine intake increased wet and dry albumen percentage, whereas dry yolk percentage decreased with increasing lysine. Total sulfur amino acid intake affected wet yolk, dry yolk, and solids in a quadratic trend, with hens fed 811 and 699 mg/d producing eggs with the greatest yolk solids. Wet and dry shell percentages were not affected by lysine or TSAA, and specific gravity decreased linearly during phase II and overall, with increased dietary TSAA. In conclusion, the dietary lysine at 959 and 816 mg/hen per day for phases I and II, respectively, optimized EW and feed efficiency. Because EP was not affected by dietary lysine, the dietary level for optimizing EP is closer to 860 and 715 mg/hen per day for phases I and II, respectively. Dietary TSAA level for maximum EP and feed efficiency was near 811 and 699 mg/hen per day but for EW may be closer to 877 and 779 mg/hen per day for phases I and II, respectively.

Evaluation of the isoleucine requirement of the commercial layer in a corn-soybean meal diet

An experiment was conducted with Hy-Line W36 hens to evaluate their Ile requirement in a corn-soybean meal diet. Five experimental diets were fed with Ile levels of 0.61, 0.58, 0.55, 0.52, and 0.49%. Supplemental amino acids (AA) were added to ensure that Ile was the first-limiting AA. Two diets with 0.55 and 0.52% Ile were also fed with higher levels of supplemental AA. A positive control (0.67% Ile) with only Met supplementation was fed, which had previously been shown to support maximum performance. All levels of Ile addition significantly increased egg production (EP), egg weight (EW), and egg contents (EC). Broken-line regression indicated a daily Ile requirement of 589.2, 601.2, and 601.4 mg per day for EP, EW, and EC, respectively, which indicated a requirement of 12.6 mg Ile per gram of EC.

Evaluation of tryptophan requirement of the commercial layer by using a corn-soybean meal basal diet

An experiment was conduced with Hy-Line W36 hens to evaluate the requirement for Trp in a corn-soybean meal diet. Seven experimental diets were fed with Trp levels of 0.12, 0.13, 0.14, 0.15, 0.16, 0.17 and 0.18%. Supplemental amino acids (AA) were added to all diets to ensure that Trp was the first-limiting AA. A positive control diet (0.20% Trp) with Met supplementation was fed that had previously been shown to support maximum performance. Egg production (EP), egg weight (EW), and egg content (EC) were significantly increased by the addition of Trp to the basal diet. Broken-line regression indicated the Trp requirement for EP and EC was 139.8 and 149.0 mg per hen/d, respectively, for EP and EC when hens had a daily EC of 45.4 g per hen/d.