Ammonia emission is a major concern for the poultry industry and can be lowered by dietary inclusion of fibrous ingredients and by lowering the dietary CP content. The objectives of this research were to determine the effects of dietary fiber and reduced-CP diets, which may lower NH(3) emission, on egg production and N balance in laying hens. A total of 256 Hy-Line W-36 hens were fed diets with 2 contents of CP (normal and reduced) and 4 fiber treatments in a 2 x 4 factorial arrangement from 23 to 58 wk of age. The fiber treatments included a corn and soybean meal-based control diet and diets formulated with either 10.0% corn dried distillers grains with solubles (DDGS), 7.3% wheat middlings (WM), or 4.8% soybean hulls (SH) added to contribute equal amounts of neutral detergent fiber. The CP contents of the reduced-CP diets were approximately 1 percentage unit lower than that of the normal-CP diets. All diets were formulated on a digestible amino acid basis to be isoenergetic. There were no effects (P > 0.05) of including corn DDGS, WM, or SH in the diet on egg production, egg weight, egg mass, yolk color, feed consumption, feed utilization, or BW gain. Although the corn DDGS and WM diets resulted in an increase (P < 0.001) in N consumption, N excretion was not affected (P > 0.10) compared with hens fed the control diet. The reduced-CP diets did not affect egg weight, feed consumption, or BW gain (P > 0.05); however, egg production, egg mass, feed utilization, N consumption, and N excretion were lower than that from the hens fed the normal-CP diets (P < 0.05). The results of this study show that the diets containing 10% corn DDGS, 7% WM, or 5% SH did not affect egg production or N excretion. However, the 1% lower CP diets caused a lower egg production and lower N excretion.

Seven separate experiments were conducted with Hy-Line W-36 hens to determine the ideal ratio of Arg, Ile, Met, Met+Cys, Thr, Trp, and Val relative to Lys for maximal egg mass. The experiments were conducted simultaneously and were each designed as a randomized complete block design with 60 experimental units (each consisting of 1 cage with 2 hens) and 5 dietary treatments. The 35 assay diets were made from a common basal diet (2,987 kcal/kg of ME; 12.3% CP; 4.06% Ca, 0.47% nonphytate P), formulated using corn, soybean meal, and meat and bone meal. The true digestible amino acid contents in the basal diet were determined using the precision-fed assay with adult cecectomized roosters. Crystalline L-Arg (free base), L-Ile, L-Lys.HCl, DL-Met, L-Thr, L-Trp, and L-Val (considered 100% true digestible) were added to the basal diet at the expense of cornstarch to make the respective assayed amino acid first limiting and to yield 5 graded inclusions of the assayed amino acid. Hens were fed the assay diets from 26 to 34 wk of age, with the first 2 wk considered a depletion period. Egg production was recorded daily and egg weight was determined weekly on eggs collected over 48 h; egg mass was calculated as egg production x egg weight. The requirement for each amino acid was determined using the broken-line regression method. Consumption of Arg did not affect egg mass, thus a requirement could not be determined. The true digestible amino acid requirements used to calculate the ideal amino acid ratio for maximum egg mass were 426 mg/d of Ile, 538 mg/d of Lys, 253 mg/d of Met, 506 mg/d of Met+Cys, 414 mg/d of Thr, 120 mg/d of Trp, and 501 mg/d of Val. The ideal amino acid ratio for maximum egg mass was Ile 79%, Met 47%, Met+Cys 94%, Thr 77%, Trp 22%, and Val 93% on a true digestible basis relative to Lys. The ideal Met and Met+Cys ratios were verified in an ensuing identical experiment with 52- to 58-wk-old hens.

Ammonia (NH(3)) emission is a major concern for the poultry industry. The objective of this research was to determine whether inclusion of dietary fiber and a reduced dietary CP content would decrease NH(3) emission from laying-hen manure. A total of 256 Hy-Line W-36 hens were fed diets with 2 levels of CP (normal and reduced) and 4 fiber treatments in a 2 x 4 factorial arrangement. The fiber treatments included a corn and soybean meal-based control diet and diets formulated with either 10.0% corn dried distillers grains with solubles (DDGS), 7.3% wheat middlings (WM), or 4.8% soybean hulls (SH) to contribute equal amounts of additional neutral detergent fiber. The CP contents of the reduced-CP diets were approximately 1 percentage unit lower than those of the normal-CP diets. All diets were formulated on the basis of digestible amino acid content and were formulated to be isoenergetic. Fresh manure was collected such that pH, uric acid, and Kjeldahl N contents could be measured. The NH(3) emission from manure was measured over 7 d by placing pooled 24-h manure samples in NH(3) emission vessels. Data were analyzed by ANOVA with Dunnett's multiple-comparisons procedure to compare results from the fiber treatments with the control, whereas the main effect of protein was used to compare the normal- and reduced-CP treatments. Dietary corn DDGS, WM, or SH lowered (P

and ImplicationsAn experiment was conducted with 48 laying hens to determine the effects of high dietary contents of corn dried distiller's grains with solubles (DDGS) on nitrogen and dry matter manure excretion as well as egg production and egg quality. Diets containing 0, 23, 46, and 69% corn DDGS were fed to laying hens for 8 weeks after an initial 4-weeklong transition period during which the dietary contents of corn DDGS were gradually increased. Egg production, egg weight, and feed consumption were measured weekly, whereas manure excretion and egg quality was measured after feeding the treatment diets for 6 weeks. Nitrogen consumption and excretion increased with increasing dietary corn DDGS contents. Egg production decreased linearly, whereas egg weight increased linearly, resulting in no significant change in overall egg output. Feed consumption increased linearly with increasing dietary corn DDGS content, causing an increase in manure dry matter excretion. It appears from this experiment that high dietary inclusion levels of corn DDGS can be fed to laying hens without adversely affecting egg production or egg quality. However, nutrient and manure dry matter excretion will increase.

Feed additives can change the microbiological environment of the animal digestive track, nutrient composition of feces, and its gaseous emissions. This 2-yr field study involving commercial laying-hen houses in central Iowa was conducted to assess the effects of feeding diets containing EcoCal and corn-dried distillers grain with solubles (DDGS) on ammonia (NH 3 ), hydrogen sulfide (H 2 S), and greenhouse gas (CO 2 , CH 4 , and N 2 O) emissions. Three high-rise layer houses (256,600 W-36 hens per house) received standard industry diet (Control), a diet containing 7% EcoCal (EcoCal) or a diet containing 10% DDGS (DDGS). Gaseous emissions were continuously monitored during the period of December 2007 to December 2009, covering the full production cycle. The 24-month test results revealed that mean NH 3 emission rates were 0.58 AE 0.05, 0.82 AE 0.04, and 0.96 AE 0.05 g/hen/day for the EcoCal, DDGS, and Control diet, respectively. Namely, compared to the Control diet, the EcoCal and DDGS diets reduced NH 3 emission by an average of 39.2% and 14.3%, respectively. The concurrent H 2 S emission rates were 5.39 AE 0.46, 1.91 AE 0.13, and 1.79 AE 0.16 mg/ hen/day for the EcoCal, DDGS, and Control diet, respectively. CO 2 emission rates were similar for the three diets, 87.3 AE 1.37, 87.4 AE 1.26, and 89.6 AE 1.6 g/hen/day for EcoCal, DDGS, and Control, respectively (P ¼ 0.45). The DDGS and EcoCal houses tended to emit less CH 4 than the Control house (0.16 and 0.12 vs. 0.20 g/hen/day) during the monitored summer season. The efficacy of NH 3 emission reduction by the EcoCal diet decreased with increasing outside temperature, varying from 72.2% in February 2009 to À7.10% in September 2008. Manure of the EcoCal diet contained 68% higher ammonia nitrogen (NH 3 -N) and 4.7 times higher sulfur content than that of the Control diet. Manure pH values were 8.0, 8.9, and 9.3 for EcoCal, DDGS, and Control diets, respectively. This extensive field study verifies that dietary manipulation provides a viable means to reduce NH 3 emissions from modern laying-hen houses.Implications: This work demonstrated that dietary manipulation can be used to reduce NH 3 emissions from high-rise laying-hen houses with no adverse effect on the hen production performances (to be presented separately). The NH 3 reduction rates could vary with different climates and hence geographic locations. The dietary manipulation to lower NH 3 emissions should be applicable to all egg production systems. The results of this study also contribute to the baseline data for improving the national air emissions inventory for livestock and poultry production facilities.