• Korean Journal of Poultry Science
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• v.30 no.2
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• pp.73-81
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• 2003

This experiment was conducted to investigate the effects of dietary energy and protein levels on the growth rate of egg breeder pullets. A total of 360 Hy-Line Brown pullets aged 2 to 6 weeks (Phase I) were fed 5 rations differing in dietary protein (17, 19 and 20%) and energy (2,800, 2,950 and 3,050 kcal/kg, TMEn) leveIs for a period of 5 weeks and those aged 6 to 10 weeks (Phase II) were fed 5 rations differing in dietary protein (15, 16 and 17%) and energy (2,800, 2,900 and 3,000 kcal/kg, TMEn) levels in order to evaluate the optimum dietary energy and protein leveIs for egg breeder pullets reared in cages. Their body weight gains were significantly influenced by the dietary protein levels (P<0.05). The dietary energy levels did not greatly affect the growth performances throughout the experimental period. The low energy and protein regimen based on NRC requirement (control) was found to produce smaller pullets and lower tibia bone measurements as compared to the higher regimen groups. With the increase in dietary energy and protein levels, tibial bone strength and ash content also gradually increased (P<0.05). There were no significant differences in the flock uniformity among the treatments. These results indicate that increases in dietary energy and protein levels above the NRC requirements appeared to be more effective in obtaining the optimal growth and bone developments of egg breeder pullets reared in cage.

• Korean Journal of Poultry Science
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• v.31 no.3
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• pp.137-143
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• 2004

The fractional synthesis rates(FSR) were measured with 2l-wk and 3l-wk-old broiler breeder pullets and hens to investigate the effect of sexual maturity on FSR. The FSR were obtained from chicken tissues and blood samples using High-Performance Liquid Chromatography/Mass Spectrometry(HPLC/MS). A L-l-13C, 15N -leucine saline solution was infused by bolus injection as a tracer into broiler breeder pullets in the experiment. A rapid HPLC/MS method was developed to measure the isotopic enrichments of leucine in plasma, tissue samples, and eggs. The enrichments of stable isotope leucine incorporated into protein and the enrichments of the stable isotope free leucine were measured in liver, breast muscle and blood samples. Two sets of experiments were conducted. In experiment one, 2l-wk-old, sexually immature broiler breeder pullets were divided into groups of three and blood samples were collected at 20 or 30 min intervals until 1.5 h from initial injection. The pullets were sacrificed in groups of three at varying time intervals for 7 h after injection. The liver, breast muscle and blood samples were removed for analysis. The FSR were estimated to be 8.7l%/day for liver, 4.06％/day for breast muscle, and 5.08％/day for blood samples in 30 minutes after injection from the enrichment ratios. In experiment two, sexually matured 3l-wk-old broiler breeder hens were assorted into groups of three and blood samples were obtained at 20 or 30 min intervals for 2 h. The FSR for blood samples were determined. The broiler breeder hens were sacrificed in groups of three at various time intervals until 7 h after injection and liver, breast muscle and blood samples were removed for analysis. The FSR were calculated to be 5.96％/day for liver. Eggs were collected from five chickens daily for 10 days after large bolus injection. The average of total enrichments of stable isotope in egg albumin was increased by 0.064% at 4 days after injection and was back to normal in 7 days.

• Korean Journal of Poultry Science
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• v.12 no.1
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• pp.1-6
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• 1985

To secure a higher percentage of fertility in hatching eggs and a higher percentage of hatchability of the fertile eggs should be of direct benefit to poultry breeder ana hatchery operators. This study was carried out to estimate the relationships of egg production and fertility in broiler breeder. The data analysed were the record of pullets (5 strains) of broiler breeder raised at Poultry Breeding Farm, Seoul National Univ. from 1982 to 1983. Since the purpose of the study was only to find out the relationships between egg Production and fertility, many other factors thought to be included in fertility were fixed as much as possible. The results were summarized as follows. 1. Mean figure of egg production rate and fertility from 30 weeks age to 60 Weeks of age to 60 weeks of age were 60.5-65.2 percent and 82.7-87.9 percent. 2. Correlation coefficients between egg Production rate and fertility were high and positive, except line K, and the coefficients have highly significant differences. 3. Regression coefficients of fertility on egg Production rate were 0.54-0.97, except line K. 4. Maximum fertility age estimated from the polynomial regression equation were 44-47 weeks. The results obtained in this study suggested that the selection of high performance strain in egg Production should improve the fertility.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.8
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• pp.1258-1265
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• 2007

Metabolizable energy (ME) required for basal metabolism, activity and growth was considered as the criterion for targeting specific increases in body weight (100 g/week) of broiler chicks during the grower phase (5-20 weeks) and its impact was evaluated on breeder performance. Broiler female chicks (460) from a synthetic dam line were randomly distributed to 4 test groups with 23 replicates of 5 birds each and housed in cages. The first group (ME-100) was offered a calculated amount of ME by providing a measured quantity of grower diet (160 g protein and 2,600 kcal ME/kg) which increased with age and weight gain (133-294 kcal/bird/day). The other three groups were offered 10 or 20% less ME (ME-90 and ME-80, respectively) and 10% excess ME (ME-110) over the control group (ME-100). From 21 weeks of age, a single breeder diet (170 g protein and 2,600 kcal ME/kg) was uniformly fed to all groups and the impact of grower ME restriction on breeder performance evaluated up to 58 weeks. The targeted body weight gain of 1,600 g in a 16-week period was achieved by pullets of the ME-100 group almost one week earlier by gaining 8.7 g more weight per week. However, pullets in the ME-90 group gained 1,571 g during the same period, which was closer to the targeted weight. At 20 weeks of age, the conversion efficiency of feed (5.21-5.37), ME (13.9-14.1 kcal/g weight gain) and protein (0.847-0.871 g/g weight gain), eviscerated meat yield, giblet and tibia weights were not influenced by ME restriction, but the weights of abdominal fat and liver were higher with increased ME intake. Reduction of ME by 10% in the grower period significantly delayed sexual maturity (169.3 d), but increased egg production (152.5 /bird) with better persistency. Improved conversion efficiency of feed, ME and protein per g egg content were also observed in this group up to 56 weeks. The fertility and hatchability at 58 weeks of age were higher in the ME-90 group compared to the control and 10% excess ME feeding. In conclusion, the present study revealed the possibility of achieving targeted weight gain in broiler growers by feeding measured quantities of ME during the rearing period with consequential benefits in breeder performance.

• Korean Journal of Poultry Science
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• v.30 no.4
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• pp.229-233
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• 2003

A study was conducted to investigate the effects of different BW control methods during rearing on laying performance of broiler breeder pullets. D-old 540 female breeder chicks (Arbor Acres) were assigned to three treatments consisted of standard BW (Control), 110% of standard BW at 12 wk of age (T1), and 90% of standard BW at 12 wk of age (T2), with three replicates of 60 birds per replicate (pen) for each treatment. At 20 wk of age, all birds from three treatments reached the BW reqired in the Arbor Acres Manual. There were no significant differences in egg production, egg weight and viability during laying period(p>0.05). However, total egg production rates were improved in T2 and T3. Average egg weight was the highest in T1 among all treatments. Fertility and hatchability were similar among treatments, but T2 tended to be higher than other treatments at 37 and 53 wk of age. No significant difference was found in hatchability among three treatments. The number of hatching egg of T2 reached 168 per year, showing higher number of eggs than did the other treatments. The number of hatched chicks in T2 was 131, which was also higher than the other treatments, but the difference was not significant. It appears that the laying performance of broiler breeder hens could be improved when their BW at 12 wk of age are kept at 90% of standard BW, and reach the standard BW at 20 week of age.

• Korean Journal of Poultry Science
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• v.11 no.2
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• pp.86-92
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• 1984

Present study was carried out to estimate phenotypic and genetic parameters influencing body weight (BW) at 4 weeks of age egg breadth (EB), egg length(EL), egg shape index (SI) and egg weight (EW) at 32 weeks of age and egg numbers (EN) up to 38 weeks of age in broiler male and female lines. The data were collected from closed White Plymouth Rock (female line; G) and Cornish (male line; C) flocks involving 1193 pullets from 211 dams and 48 sires in 1982. The results obtained are summarized as follow: 1. General performance for various trails of lines C and G. The means and standard deviations of BW, EB, EL, SI, EW and EN were 668.34${\pm}$47.18, 4.23${\pm}$0,11, 5.49 ${\pm}$0.19, 77.06${\pm}$2.98, 55.73${\pm}$3.54 and 59.72${\pm}$13.39 in line C, respectively and 487.89${\pm}$ 41.43, 4.22${\pm}$0.11, 5.51${\pm}$0.19, 76.72${\pm}$3.20, 55.43${\pm}$3.26 and 76.93${\pm}$12.17 in line G, respectively. 2. Heritability Heritabilities were estimated from sire, dam and combined components. Estimates for BW, EB, EL, SI, EW and EN from combined components were 0.30, 0.29, 0,40, 0.22, 0.45 and 0.60 in line C, respectively and 0.33, 0.23, 0.28, 0.13, 0.49 and. 0.33 in line G, respectively. 3. Correlation Genetic and phenotypic correlations showed similar trend in line C and G. Genetic correlations, estimated EW with EB and EL, were high and positive (line C; 0.99, 0.75, respectively and line G; 0.94, 0.82, respectively), also correlation of EB with EL was 0.58 (both lines; 0.58). High and negative genetic correlations were shown between SI and EL in line C and G (-0.70, -0.65, respectively). Genetic correlations between SI and EW were relatively low and negative in line C and G (-0.11, -0.19, respectively) and between SI and EN were relatively low and positive in line C and G (0.25, 0.17, respectively). Between other traits, low genetic correlations were shown in both lines, High and positive correlation was estimated between hatchability and egg shape index and polynomial regression of egg shape index on hatchability was estimated; Y=-216.77＋7.6216X-0.0146939X$^2$.