This study was conducted to determine lysine requirement in laying hens, using plasma free lysine levels as a response criterion. The basal diet used was based on corn- corn gluten meal soybean meal, and contained 0.58% lysine, Nine graded levels of lysine (0.04, 0.08, 0.12, 0.16, 0.2,0.24,0.28,0.32,0.36%) were added to the basal diet. Each experimental diet was fed to 48 laying hens in a randomized complete design with 4 replicates in each treatment. Broken-line method was employed for estimation of lysine requirement. Dietary lysine levels exerted a significant effect on egg weight, egg mass output, feed intake (P<0.01), and feed conversation ratio (P<0.05), but did not significantly affect egg production. Based on egg mass output, feed conversion ratio and plasma free lysine responses, lysine requirements were estimated at 675, 790 and 785 mg per hen -day; respectively. The results suggest that plasma free lysine could be a precise indicator (R2=0.96) for determining lysine requirement in laying hens. In conclusion, based on the results of this experiment, daily lysine requirement of laying hens during peak egg production was estimated at 785-790 mg per hen-day.

This study was conducted to determine lysine requirement of laying hen during peak egg production from 26 to 42 weeks. of age. The basal diet used was based on corn- corn gluten meal- soybean meal and contained 0.58% lysine. To the basal diet nine graded Levels of Lysine (0.04, 0.08, 0.12, 0.16, 0.2, 0.24, 0.28, 0.32, 0.36%) were added. The experimental diets were fed for 16 week. Each experimental diet was fed to 48 Laying hen in a randomized complete design with 4 replicate for each treatment. Broken-line and exponential models were used for estimation of lysine requirement. Dietary lysine levels had a significant effect on egg weight, egg mass output, feed intake(p< 0.01) and feed conversation ratio(p< 0.05) but hadnot significant effect on egg production .Based on egg mass output response and the fit of Broken-line and Exponential models the requirement for total lysine were estimated 645 and 710 mg per hen - day; respectively. Based on feed conversion efficiency Response and the fit of Broken-line and Exponential models the requirement for total lysine was estimated 750 and 810 mg per hen- day. In conclusion, the results of this experiment indicated that daily lysine requirement of laying hen during peak egg production was estimated 810 mg per her- day or 53 gram per kilograme of dietary crude protein.

The aim of the present study was to determine the appropriate standardized ileal digestible lysine requirement to 49 day of olds in male BUT,6 turkey poults. Experiment 1 and 2 were used from 8-28 and 28-49 d-old respectively. One hundred sixty male BUT,6 turkeys in each experiment were used in a completely randomized design with eight treatments (8 levels of standardized ileal digestible lysine in 4 replicates of 5 birds in each. Standardized ileal digestible lysine level of basal diets in experiment1 and 2 were 1.33 and 1.15% respectively. Different levels of lysine (0.075, 0.15, 0.225, 0.3, 0.375, 0.45, 0.525%) were added to basal diets. In Experiment 1, By using of Broken Line- Linear Ascending, Quadratic Polynomial and Broken Line- Quadratic Ascending standardized ileal digestible lysine requirements for weight gain were 1.56±0.05, 1.67 and 1.65±0.1 and for FCR were 1.58±0.05, 1.75 and 1.74±0.1% respectively. In Experiment 2, By using of Broken Line - Linear Ascending, Quadratic Polynomial and Broken Line- Quadratic Ascending standardized ileal digestible lysine requirements for weight gain were 1.47±0.11, 1.57 and 1.49±0.05 and for FCR were 1.57±0.17, 1.61 and 1.59±0.08% respectively. In conclusion, standardized ileal digestible lysine requirements in starter for body weight gain and FCR ranged between 1.56 to 1.67 and 1.58 to 1.75% respectively. In Experiment2, standardized ileal digestible lysine requirements for body weight gain ranged between 1.47 to 1.57 and for FCR between 1.57 to 1.61%.

An experiment was conducted to reevaluate the digestible lysine requirement of Arian male broilers by comparing the performance of chicks fed different levels of cottonseed meal (CSM) on a total amino acid (AA) versus a digestible AA basis. Four hundred and thirty two (432) Arian male broiler chicks were allotted to 18 treatments with four replicates of six chicks each in a completely randomized block design in a factorial arrangement with two factors (two levels of digestible lysine × nine different diets). The first of the eighteen treatments was the corn and soybean meal control diet based on previously determined digestible lysine requirement for maximum body weight gain. Diets 2 to 5 contained 5, 10, 15 or 20% CSM, respectively and were formulated to contain levels of total AA equivalent to those in the first treatment. Diets 6 to 9 contained the same levels of CSM as diets 2 to 5 but the diets were formulated to be equal in digestible AA content to the first treatment. Treatments 10 to 18 were the same as treatments 1 to 9, but on the basis of determined digestible lysine requirement for maximum feed efficiency. Formulating diets containing CSM on a digestible AA basis resulted in an improvement in chick performance compared to those formulated on a total AA basis (P<0.01). The lessening of chick performance with diets formulated on a total AA basis compared to a digestible AA basis indicated that the previously determined digestible lysine requirement for the Arian broiler strain may be correct.  

The present research was conducted to estimate the dietary lysine (Lys) requirement of growing female quail base on performance and carcass constitutes at 24 to 42 d of age. A dose-response diet mainly based on corn, corn gluten and soybean meal was used. Lys content was minimized in dose-response diet (10 g/kg) while assuring the minimum levels of all other essential amino acids in a manner that would meet or exceed recommendation. This experiment was carried out in a complete randomized design arrangement with 6 dietary Lys level; 10.0, 11.5, 13.0, 14.5, 16.0 and 17.5 g/kg, from 21 to 42 d of age. Each treatment was consisted of 5 floor pens as replicate with 50 quail chicks. As a result of this study increasing dietary Lys level, body weight, body weight gain and feed conversion ratio improved significantly (P<0.05). Feed intake, carcass weight, breast weight and yield, and thigh weight were significantly (P<0.05) affected by dietary Lys. The thigh yield at 42 d of age were not influenced significantly (P>0.05) by dietary Lys. Our results suggested that Lys requirement is 13.5 and 14.7 g/kg when feed conversion, body weight (BW) gain are considered and is at least 13.6 and 15.0 g/kg when and breast and thigh meat properties are taken into account in female Japanese quails at 21-42 d of age for second order polynomial and quadratic broken-line models respectively. These results indicated that the Lys requirement of 13.0 g/kg (total basis) is not adequate from 21 to 42 d of age for female Japanese quails. Future research, however, should determine lysine needs for immune system functions of quails reared in conventional environments or during an infectious challenge.

An experiment was conducted to determine the dietary digestible lysine requirement of male and female broiler chickens (Arian) during the period from 6 to 21 days posthatching. An amino acid-fortified basal diet containing corn and soybean meal as intact protein sources provided 20 % CP, and 3200 kcal AMEn / kg. In this experiment 150 male and 150 female chicks were allocated on the basis of BW to 12 treatments in a factorial arrangement (two sexes at six digestible lysine levels) with five replications of five chicks each in a completely randomized design (CRD). The digestible lysine levels fed were 0.85, 0.95, 1.05, 1.15, 1.25 and 1.35%. The growth rate and feed efficiency of birds fed the basal diet fortified with a surfeit level of l-Lysine-HCl were equal to those of birds fed a cornsoybean meal positive control diet. Average body-weight gain (ABWG) and gain: feed (GF) responded quadratically (P<0.05) to incremental dietary lysine addition. Subjecting the growth data to broken-line analysis indicated that the digestible lysine requirement for maximum body weight gain was 1.075% for males and 1.049% for females. The lysine requirement for maximum feed efficiency was 1.179% for males and 1.149% for females. Male chicks required a higher level of dietary lysine than females for both maximal ABWG and GF. Regardless of sex, 8.8% more digestible lysine (percentage of diet) was required for maximal GF than that needed for maximal ABWG.

Two experiments were conducted to determine lysine (Lys) requirements of two commercial strains, Ross 308 and Cobb 500, from 15 to 28d of age. Basal diet was formulated to be adequate in all nutrients except for Lys. Incremental levels of supplemental Lys were added to the basal diet generating six experimental treatments in a range from 0.60 to 1.20% digestible Lys. Birds were randomized across 48 floor pens (4 replicates and 12 birds in each replicate) in completely randomized design and each pen was fed one of six amino acid levels.Body weight gain, feed intake, feed conversion ratio, and digestible Lys intake responded quadratically to graded levels of digestible Lys, and interaction effects between Lys and strain were significant for all performance traits except for feed conversion ratio. Digestible Lys requirements were estimated using broken-line linear and broken-line quadratic models. In Ross 308, digestible Lys requirements for body weight gain and feed conversion ratio were estimated at 0.95 and 1.08% of diet, respectively, by broken-line linear model. Digestible Lys need for body weight gain was optimized at 1.05% of diet using broken-line quadratic model. In Cobb 500, Lys requirements for body weight gain and feed conversion ratio were estimated at 0.89 and 0.98% of diet, respectively, by broken-line linear model. Digestible Lys need for body weight gain and feed conversion ratio were optimized at 0.99 and 1.14% of diet using broken-line quadratic model.