Settable Egg Production Research Articles

Evaluation of industry strategies to supply dietary chelated trace minerals (Zn, Mn, and Cu) and their impact on broiler breeder hen reproductive performance, egg quality, and early offspring performance

Dietary trace minerals have profound functions in broiler breeder reproduction. Organic hydroxy analog of methionine (HMTBa) trace minerals have been included at lower levels in poultry feeds compared to inorganic sources without affecting performance and in some cases improving it. We compared 3 breeder hen trace mineral blends of economic interest to a large U.S. integrator. Treatment diets (fed wk 26–65) provided Zn, Mn, and Cu (mg/kg), respectively: CTL = control, predominantly inorganic trace minerals (143–180–123); ORG = reduced levels using solely HMTBa trace minerals (50–60–15); and MIX = a blend of inorganic/HMTBa trace minerals (75/25–90/30–22.5/7.5). On average, ORG-fed hens were 1.3 and 1.1% heavier compared to CTL and MIX hens, respectively (P = 0.002). Overall (wk 25–65), hens fed the MIX diet had higher egg production (P < 0.001) and laid heavier eggs (P = 0.038) compared to hens fed the CTL or ORG diet. During the second half of lay, MIX-fed hens showed improved eggshell quality (P ≤ 0.037) and cuticle deposition (P = 0.019). Fertility and hatchability were unaffected by diet (P ≥ 0.205). Broilers hatched from young ORG hens (29 wk) had higher bone mineral density (P = 0.004) and after a 7-day grow-out (P = 0.047) when obtained from ORG hens of 41 wk of age. In conclusion, the industry levels provided by combining inorganic and HMTBa trace minerals in breeder hen diets were advantageous for sustaining high-quality settable egg production.

Improved offspring performance of broiler breeder hens fed amino acid complexed trace minerals

The present study aimed to evaluate the effects of partial substitution of inorganic trace minerals ( ITM ) by amino acid complexed minerals ( AACM ) on broiler breeder hens’ performance and offspring. A total of 640 Cobb 500 broiler breeder hens, 22 wk of age, were allocated to four dietary treatments: T1- (Control) contained ITM forms of Zn, Mn, Cu, Fe and Se at 100, 100, 10, 50 and 0.30 ppm, respectively; T2- (Partial replacement) of Control by AACM Zn, Mn, Cu, and Se at 60, 60, 3, and 0.15 ppm of ITM, and 40, 40, 7, and 0.15 ppm of AACM, respectively.; T3- (Partial replacement) of Control, same as T2 but with Fe at 10 and 40 ppm of ITM and AACM, respectively; T4- (On Top) supplementation of Zn, Mn, Cu, Se and Fe (T1+T3). Laying production was evaluated from 26 to 66 wk, whereas egg quality was evaluated at 35, 45, 55, and 65 wk of age. At each period, eggs were incubated and evaluated for hatchability parameters and chick quality. At 66 wk of age, eggs were incubated to obtain 800-day-old male chicks for the progeny performance trial. Total and settable egg production and incubation parameters were not affected by supplementation treatments (P > 0.05). Eggshell breaking strength significantly increased (P < 0.05) in the On Top supplementation group compared to the Control. The offspring from hens fed partially Zn, Mn, Cu, Se and Fe AACM had higher body weight gain ( BWG ) in the first week (P < 0.05) and maintained a smaller feed conversion ratio ( FCR ) from 1 to 35 d compared to the offspring of Control ITM group (P < 0.05). Maternal AACM supplementation increased offspring BWG and FCR from 1 to 7 d and 1 to 35 d, respectively.

Impact of growth curve and dietary energy-to-protein ratio on productive performance of broiler breeders

The impact of growth curve (GC) and dietary energy-to-protein ratio on productive performance of broiler breeder females was investigated from 0 to 60 wk of age. One-day-old pullets (n = 1,536) were randomly allotted to 24 pens according to a 2 × 4 factorial arrangement, with 2 GC (standard growth curve = SGC or elevated growth curve = EGC, +15%) and 4 diets, differing in energy-to-protein ratio (96%, 100%, 104%, or 108% AMEn). Feed allocation per treatment was adapted weekly based on the desired GC, meaning that breeders fed the different diets within each GC were fed according to a paired-gain strategy. Linear and quadratic contrasts for energy-to-protein ratio for each GC were evaluated. Elevated growth curve breeders had an earlier sexual maturity (∆ = 4.1 d) than SGC breeders. Egg weight was higher for EGC breeders (∆ = 2.3 g) than for SGC breeders over the whole laying phase (22–60 wk). No differences between EGC and SGC breeders were observed on settable egg production. An increase in dietary energy-to-protein, at a similar BW, led to a linear increase in age at sexual maturity (β = 0.14 d/% AMEn). From 22 to 40 wk of age, an increase in dietary energy-to-protein ratio led to a linear decrease in egg weight (β = -0.06 g/% AMEn), regardless of GC. An interaction between GC and dietary energy-to-protein ratio was observed on settable egg production in this phase. An increase in dietary energy-to-protein ratio led to a linear decrease on settable egg production, which was more profound in EGC breeders (β = -0.70 eggs/% AMEn) than in SGC breeders (β = -0.19 eggs/% AMEn). From 41 to 60 wk of age, an interaction between GC and dietary energy-to-protein ratio was observed on egg weight. In the EGC, an increase in dietary energy-to-protein ratio led to a linear decrease in egg weight (β = -0.13 g/% AMEn), whereas in the SGC, a linear increase in egg weight was observed (β = 0.03 g/% AMEn). From 41 to 60 wk of age, no differences between diets were observed on settable egg production. It can be concluded that a higher GC of breeders has beneficial effects on egg weight, while maintaining settable egg production. Feeding breeders a lower dietary energy-to-protein ratio stimulated productive performance of broiler breeder hens, mainly during the first phase of lay. This effect was more profound when breeders were fed according to a higher GC.

Manganese requirements of broiler breeder hens

The present research was conducted to assess Mn requirements of broiler breeder hens. One hundred and twenty Cobb 500 hens, 22 wk of age, were individually allocated in cages. After fed a Mn-deficient diet (22.2 ppm), hens were randomly placed in treatments having 6 increments of 30-ppm Mn. All trace minerals were from laboratory grade sources being Mn from Mn sulfate (MnSO4H2O). Treatments were fed for 4 periods of 28 d. There were no interactions between dietary Mn and period for any evaluated response (P > 0.05). Requirements of Mn for hen day egg production and settable egg production were 115.8 and 56.6 ppm and 122.1 and 63.6 ppm (P < 0.05), respectively, using quadratic polynomial (QP) and broken line quadratic (BLQ) models, whereas total eggs and total settable eggs per hen had Mn requirements estimated at 115.7 and 56.6 and 121.8 and 61.7 ppm (P < 0.05), respectively. Number of cracked, defective, and contaminated eggs decreased, whereas hatchability, hatchability of fertile eggs, eggshell percentage, and eggshell palisade layer increased when hens were fed diets having 48.5 to 168.2-ppm Mn (P < 0.05). Maximum responses for egg weight and eggshell percentage were 117.7 and 63.6 ppm as well as 131.6 and 71.0 ppm (P < 0.05), respectively, using QP and BLQ models. Breaking strength and egg specific gravity had Mn requirements estimated at 140.2 and 112.7 ppm as well as 131.3 68.5 ppm (P < 0.05), whereas eggshell palisade layer and eggshell thickness were maximized with 128.8 and 68.8 ppm and 140.2 134.2 ppm, respectively, for QP and BLQ models (P < 0.05). Maximum yolk Mn content values were obtained using 118.0- and 118.4-ppm Mn by QP and BLQ models, respectively. The average Mn requirements estimated for QP and BLQ models is 128.4 and 92.3 ppm Mn (18.7 and 13.5 mg/hen/d), respectively, which is much lower than what has been currently recommended in commercial production.

Estimating total lysine requirement for optimised egg production of broiler breeder hens during the early-laying period

The production performance of broiler breeder hens in response to different levels of total lysine during the early laying period was investigated. A total of 126 Ross 308 parent stock hens were offered one of seven dietary treatments formulating elevated contents of total lysine ranging from 0.55% to 0.79% (0.04 scale; 133 g of feed) from 23 to 29 weeks of age. Each treatment had six replicates with three birds per pen. Body weight was recorded triweekly and eggs were collected and weighted at 9:00 am daily. One hen from each pen was euthanized to collect blood samples and visceral organs were harvested and weighed. Egg production, egg weight and egg mass were lower (p < 0.05) in hens offered a diet containing 0.55% total lysine compared to those fed the diet containing higher total lysine. Hens offered a diet containing 0.71%, 0.75%, and 0.79% total lysine had greater (p = 0.008) egg production rate compared to those offered a diet containing lysine less than 0.71%. The number of total eggs produced tended to be greater (p = 0.083) in hens offered a diet containing 0.71 and 0.75% total lysine compared to the other treatments. The number of settable egg production was higher (p < 0.001) in hens offered a diet contacting 0.79% total lysine compared to those fed the diet containing lower levels of total lysine. The relative weights of oviduct and ovary were lower (p < 0.05) in hens offered a diet containing 0.59% total lysine compared to the other treatments. No difference found in body weight, the number of total eggs, double-yolk eggs and abnormal shell eggs among the treatments. The urea nitrogen, estradiol-17 beta and progesterone in plasma were not affected by treatments. Based on linear- and quadratic-plateau models, total lysine requirements for egg production, settable egg production and egg mass at the early laying period were to be 0.73%, 0.77%, and 0.71%, respectively. Modern broiler breeder hens likely require higher total lysine than NRC recommendation in a diet for enhancing productivity during the early-laying period.

Zinc requirements of broiler breeder hens

One hundred and twenty Cobb 500 hens, 20 wk of age, were randomly allocated into individual cages with the objective of estimating their Zn requirements. The study was composed of 3 phases: adaptation to cages (basal diet), depletion (deficient diet containing 18.7 ± 0.47 ppm Zn) for 7 wk, and experimental phases. Hens were fed diets with graded increments of Zn sulfate heptahydrate (ZnSO4·7H2O), totaling 18.7 ± 0.47, 50.3 ± 10.6, 77.3.0 ± 11.0, 110.2 ± 12.8, 140 ± 12.2, and 170.6 ± 13.2 ppm analyzed Zn in feeds for 12 wk (experimental phase). Requirements of Zn were done using quadratic polynomial (QP), broken line quadratic (BLQ), and exponential asymptotic (EA) models. In general, the non-linear statistical models were the ones that best fit the results in this study. Requirements obtained for hen day egg production and settable egg production were 83.3, 78.6 ppm and 61.4, 65.4 ppm for period of 33 to 36 wk, and 63.3, 53.1 and 60.4, 46.1 ppm for period of 37 to 40 wk, and 62.8, 52.8, and 67.7, 62.1 ppm for period of 41 to 44 wk, respectively, using BLQ and EA models. Total eggs and total settable eggs produced per hen had Zn requirements estimated as 75.7, 64.7 ppm, and 56.5, 41.5 ppm, respectively, for BLQ and EA models, whereas for alkaline phosphatase and eggshell percentage were 161.8, 124.9 ppm and 126.1, 122.4 ppm, using QP and BLQ models. Maximum responses for Zn in yolk for periods of 37 to 40 and 41 to 44 wk were 71.0, 78.1 and 64.5, 59.6 ppm, respectively, using BLQ and EA models. Breaking strength had Zn requirements estimated at 68.0 and 96.7 ppm, whereas eggshell palisade layer and eggshell thickness were maximized with 67.9, 67.9 ppm, and 67.7, 64.4 ppm, respectively, for BLQ and EA models. The average of all Zn requirement estimates obtained by EA and BLQ models in the present study was 72.28 ppm or 11.1 mg/hen/d.

English

An experiment was conducted to evaluate responses of feed-satiated and feed- restricted breeder hens to daily injection of progesterone (P4). A total of 64 Cobb 500 hens were fed either restricted or ad libitum from 27 to 38 wk of age. Fourteen laying hens from each group were selected to conduct P4 injection assay. Half of birds in each group (n = 7) were injected daily by 2.5 mg P4/kg BW and remaining birds were used as control. The P4 was injected subcutaneously, at the base of the neck daily (at 0900 h) for 21 d. Settable and abnormal eggs were recorded daily. Blood samples were taken just before initiation of injections, 10-d and 20-d after initiation of injection. Plasma samples were analyzed for glucose, cholesterol, triacylglycerol (TAG), P4, estradiol (E2), testosterone, T3 and T4 concentration. Settable egg production declined following P4 injection, whereas total egg production (including soft shell egg) remain at high levels in injected birds during the first week after initiation of P4 injection. Progesterone injection in feed-satiated and feed-restricted birds resulted in ovary regression; the ovary of these birds had no hierarchical follicle. Progesterone injection increased incidence of holding hardshelled eggs in the uterus. Plasma E2 concentrations were affected both by feeding pattern and P4 injection. Progesterone injection depressed plasma E2 concentration in both ad libitum and restricted fed hens. Hens with free access to feed had significantly lower plasma E2 levels compared to restricted fed hens. Our results revealed that whereas injection of P4 induced frequent ovulation early in the injection period in both feed- satiated and feed-restricted breeder hens; however this higher ovulation rate did not result in more settable egg production.

The Effect of Feed Restriction Programs and Growth Curves on Reproductive Performance, in vitro Lipogenesis and Heterophil to Lymphocyte Ratios in Broiler Breeder Hens

An experiment was conducted to compare Everyday (ED) and Skip-a-day (SK) feeding programs and early Slow growth (SLOW) and Broilerized (BROIL) treatments. Feed restriction programs were implemented from 4 weeks to 5% production. The SLOW group was fed to reach 75% of standard BW by 12 weeks and then to reach standard BW by 21 weeks. The BROIL group was fed ad libitum till 7 weeks and then severely restricted to reach standard BW by 21 weeks. Parameters measured included BW, uniformity, age at Sexual Maturity (SM), total and settable egg production, body composition, liver size and composition, in vitro Lipogenesis (IVL) and Heterophil-Lymphocyte ratio (H/L). Breeder production performance was evaluated through 45 weeks of age. Birds fed ED grew more efficiently than SK or SLOW. The BROIL treatment resulted in significantly worse feed utilization than all other groups. Frame size was consistently greater in BROIL pullets and consistently smaller in SLOW pullets. Birds fed ED reached SM before SK, who in turn reached SM before SLOW or BROIL birds. Egg production was significantly higher in ED than SK, which in turn was higher than either SLOW or BROIL. The difference of nearly 17 total eggs per hen between ED and BROIL hens could not be explained by differences in BW or body composition. Liver weight and IVL was elevated in SK and SLOW pullets above ED pullets during rearing. Liver weight and IVL were lower in BROIL pullets than other groups during rearing, but after photostimulation dramatic increases in liver weight and IVL resulted in this trend being inverted by 27 weeks. As an indicator of stress, H/L ratios were elevated above ED pullets in SK, SLOW and BROIL pullets at various times during rearing. These times generally coincided with the periods of most severe feed restriction. Feeding regimens and growth curves have a major influence on efficiency and reproductive performance in broiler breeders. These effects were not attributable solely to differences in BW and body composition. The depression of IVL in broilerized pullets even after restricted feeding was implemented was of great interest and warrants further examination.

산란종계 사료 내 이소플라본 및 Casein Phosphopeptide의 첨가가 종란 생산성 및 후기 난각질에 미치는 영향

This experiment was conducted to investigate the effects of dietary Ca levels and some feed additives such as isoflavone and casein phosphopeptide (CPP) on eggshell quality and hatching egg production in aged egg-type breeder hens. A total of three hundred and sixty, 56-week-old Hy-Line Brown breeder hens were divided into six groups and fed experimental diets of two levels of Ca (3.3% or 3.6%) either with addition of 0.2% isoflavone, 0.5% CPP or devoid of all for 5 weeks. There were no significant differences in laying performances and settable egg production among the groups. Significant increases (P<0.05) in eggshell strength were observed with increasing dietary Ca and addition of isoflavone, but not with addition of CPP. Fertility and hatchability were not influenced by dietary Ca and addition of isoflavone or CPP. The treatment had few significant effects on tibial proximal compositions and breaking strength. The concentrations of Ca, P, estrogen and calcitonin in serum were not affected by the dietary treatments. These results indicated that relatively high level of dietary Ca in combination with isoflavone had a beneficial effect on improving eggshell quality in aged egg-type breeder hens. But hatching egg production was not affected by dietary isoflavone or CPP.

Reproductive Performance and Immune Status of Caged Broiler Breeder Hens Provided Diets Supplemented with Either Inorganic or Organic Sources of Zinc from Hatching to 65 wk of Age

In short-term studies, organic sources of supplemental zinc in broiler breeder hen diets have produced inconsistent results regarding reproductive performance and immune status. Furthermore, there are limited data addressing the long-term effects of dietary zinc source on broiler breeder hen performance. This study examined reproductive and immune responses of caged broiler breeder hens provided diets supplemented with 160 ppm zinc from either ZnSO4 (control), AvailaZn zinc-amino acid complex (ZnAA), or a mixture of ZnAA and ZnSO4 (80 ppm zinc from each) from hatching to 65 wk of age. Egg specific gravity, settable egg production, and estimated chick production were optimized when hens were provided diets that were supplemented with zinc from a mixture of ZnAA and ZnSO4. Immune response to phytohemagglutinin-P and antibody titers to Newcastle disease virus were increased with birds given diets supplemented with 160 ppm zinc from ZnAA. Generally, supplementing diets with a combination of ZnAA and ZnSO4 resulted in superior reproductive performance of caged broiler breeder hens, while supplementing with ZnAA enhanced immune status of hens.

The effects of age at photostimulation and dietary protein intake on reproductive efficiency in three strains of broiler breeders varying in breast yield

The effects of strain, age at photostimulation, and dietary CP intake during the early lay period on sexual maturation and egg production parameters in broiler breeder hens were determined. Three Arbor Acres strains, Classic, Feather Sexable Yield (FSY), and an experimental line (EXP), were reared in floor pens. At 19 wk of age, pullets were moved into individual cages. At 20 wk of age one-half of the birds were photostimulated by increasing the day length from 8L:16D to 15L:9D. The remaining birds were photostimulated at 23 wk of age. The birds were fed 16 or 18% CP diets from 19 to 32 wk of age. The Classic hens achieved sexual maturity 4 d before the EXP hens. Delaying photostimulation to 23 wk of age delayed sexual maturity but the rate of sexual maturation was accelerated after photostimulation occurred. Egg weight at sexual maturity was higher for the later photostimulated birds. The FSY and EXP hens, selected for more white-meat yield than the Classic hens, were heavier in BW but had lower settable egg production than the latter. Feeding 18% CP resulted in a higher BW throughout the trial, as compared to the 16% CP diet. There was a response to dietary CP and photostimulation age on initial egg weight and the number of double-yolked eggs. Early photostimulation was not advantageous because egg production parameters were not affected. Both Classic and FSY strains performed well when fed 18% CP; however, EXP hens benefited from 16% CP intake.

Effects of low dietary protein and different allocations of food during rearing and restricted feeding after peak rate of lay on egg production, fertility and hatchability in female broiler breeders

1. A 3 × 2 × 2 factorial experiment was conducted with boiler breeder females to determine the effects of body weight gain (three levels) and conventional or lower crude protein concentrations in the rations during rearing, and restricted or ad libitum feeding after the peak rate of lay on egg production, fertility, hatchability, mortality and food consumption. 2. Compared with ad libitum feeding, conventional food restriction resulted in a decrease in average daily food consumption of 0.6 during rearing, 0.2 during early lay and an increase of 0.4 after the peak rate of egg production. Mortality was decreased by more than half. 3. Restricted birds had higher total and settable egg production, fewer defective or damaged eggshells and higher fertility and hatchability than those fed ad libitum . The modified (more generous) rearing programme resulted in lower rates of egg production and higher rates of mortality compared with the conventional food restriction programme. 4. Low-protein rearing rations were associated with higher rates of food intake, higher mortalities and lower rates of egg production than the conventional protein rations. There were no differences in the fertility or hatchability of eggs between birds fed on the two concentrations of dietary crude protein. 5. Ad libitum feeding post-peak was associated with higher rates of mortality to 60 weeks of age. Postpeak feeding had little effect on the rate of lay or egg weight in conventionally restricted birds fed high protein rations or in birds fed ad libitum . Restricted feeding post-peak decreased the rate of lay and egg weight in birds on the modified restriction programme and in conventionally restricted birds fed on the low protein rations. There was no effect of post-peak feeding on fertility or hatchability of eggs. 6. The total numbers of saleable chicks per kg food consumed were 1.83, 1.72 and 0.52 for conventional, modified and ad libitum feeding during rearing; 1.56 and 1.15 for restricted and ad libitum feeding post-peak: there were no differences associated with protein concentrations of rations fed during rearing.

Effects of lighting program on reproductive development of female large white turkeys

Female commercial turkeys were used to investigate the effects of lighting program on onset of egg production, reproductive development and egg production. Under a conventional (CON) lighting program, birds were photostimulated from 5L:19D to 14L:10D at 29 wk, with an additional hour of daylight added at 35 wk of age (15L:9D). The alternate (ALT) lighting program involved weekly 0.5 h decreases in day length from 14L:10D at 3 d to 6L:18D, at 17 wk followed by weekly 0.5-h increases in day length beginning at 20 wk, to a maximum of 15L:9D at 38 wk of age. Birds were killed either at 3-d intervals (140–206 d), to assess reproductive development, or on the day following the first oviposition. A final group of birds was maintained for egg-production records. The ALT birds reached first egg at a younger age (220 d vs. 224 d) and lower body weight (11.18 kg vs. 11.88 kg) than CON birds did. The oviduct of the CON treatment reached its mature weight 5 d before the ovary. The growing oviduct of the ALT birds reached its mature weight 4 d after the ovary. Ovarian development of the ALT birds was accelerated by 10 d, compared with that of the CON birds. The number of unreconciled ovulations, as evidenced by postovulatory follicles at first oviposition, did not differ between treatments (1.2, ALT; 1.6, CON). The number of large follicles was not different between the two treatments (12.9, ALT; 14.3, CON [P = 0.092]). First-egg weights were significantly lower (70.6 g, ALT; 77.2 g, CON) for the ALT treatment, which also had a higher incidence of small eggs for the first 4 wk of production (3.31%, ALT; 0.82%, CON). Total egg production and total settable egg-production did not differ between treatments. Key words: Turkey, sexual maturation, lighting program, ovary, oviduct

Effects of photostimulatory lighting and feed allocation in female broiler breeders 1. Reproductive development

Changes in carcass traits during sexual maturation were studied with female Shaver Starbro breeders in a 2 × 2 factorial design with two lighting programs and two feeding programs. Pullets were individually caged in a light tight facility at 20 wk of age. The light period of fast photoperiod (FP) hens was changed from 8L:16D to 15L:9D at 20 wk of age. Slow photoperiod (SP) hens were switched from a 8L:16D photoperiod at 20 wk to 11L:13D, with increases to 12L:12D, 13L:11D, 14L:10D, and 15L:9D weekly to 24 wk of age. Slow feed (SF) hens were given small (5 g or less) weekly increases in feed allocation from 20 to 25 wk. Fast feed (FF) hens received larger feed allocations than the SF birds from 20 to 25 wk (maximum difference of 25 g more feed than SF hens received). Birds were processed at weekly intervals between 20 and 26 wk of age (Group A) or at sexual maturity (Group B), which was considered to be the day of the first oviposition.Age at sexual maturity did not differ due to photostimulation or feeding treatment. Whereas feeding program had no effect on carcass composition parameters at sexual maturity, the SP hens had a higher relative carcass lipid content at the expense of protein and ash content compared to FP hens. The weight of the large yellow ovarian follicles (LYF) at sexual maturity was affected by feeding regimen (FF, 50.2 g; SF, 43.6 g) and photoperiod (FP, 43.2 g; SP, 50.6 g). While hens on the SP photostimulation program had 8.9 LYF compared to 8.0 in FP hens at sexual maturity, the FF feeding regimen hens had 9.0 LYF compared to 7.9 in SF hens. The gradual feeding program of the SF treatment may be a potential means of limiting follicle recruitment and thereby potentially increasing settable egg production compared with feeding programs using more rapidly increasing feed allocations. Key words: Broiler breeders, photostimulation program, feed restriction, ovary morphology

The Use of Feed Restriction for Improving Reproductive Traits in Male-Line Large White Turkey Hens.: 2. Ovary Morphology and Laying Traits

The influence of feed restriction during rearing was investigated in male-line Large White breeder hens with regard to effects on ovarian morphology, egg production, laying patterns, and egg characteristics. Two hundred poults were reared from 4 to 28 wk of age under four treatments as follows: full-fed controls (FF), low-protein diet (12% CP from 12 to 28 wk; LP), and reduced BW (10 to 20% lower BW than FF; R10 and R20). At photostimulation (28 wk), all birds consumed a commercial breeder diet ad libitum for the remainder of the study (48 wk of age).Settable egg production (eggs per hen) to 48 wk for all hens, and those in lay was: FF, 39.4 (48.6); LP 42.7 (51.7); R10, 41.4 (52.8); R20, 40.7 (55.4). Inferior egg production per bird in R10 and R20 hens reflected a reduced persistency of lay. At first egg, hens of all treatments had a mean of 4.9 postovulatory follicles (POF) not accounted for by an egg. Number of unreconciled POF correlated with abdominal fat pad weight (P ≤ .01). Ovary weight correlated with BW (P < .0001) and fat pad weight (P < .0004). Proportion of yolk and shell in the egg and egg specific gravity were improved with feed restriction. Sequence length was longest in R20 treatment hens and pause length shortest in R10 and R20 hens. Incidence of multiple-follicle sets was reduced in the R10 and R20 treatments. Feed restriction during rearing can potentially improve laying characteristics by altering ovarian morphology without limiting shell quality or yolk size. Quantitative feed restriction was most effective at improving egg quality, reducing average pause length, and reducing ovarian multiple-follicle sets. If problems with persistency of lay are addressed, the R10 and R20 treatments are the recommended rearing restriction treatments for male-line turkey breeder hen candidates.

The Use of Feed Restriction for Improving Reproductive Traits in Male-Line Large White Turkey Hens.: 1. Growth and Carcass Characteristics

The influence of feed allowance during rearing was investigated in male-line Large White breeder hens. A flock of 200 poults was reared from 4 to 28 wk of age under four treatments as follows: full-fed controls (FF), lowprotein diet (12% CP from 12 to 28 wk; LP), and reduced BW (10 or 20% lower BW than FF; R10 and R20). At photostimulation (28 wk), all birds consumed a commercial breeder diet ad libitum for the remainder of the study (48 wk of age).Body weight differed among treatments during most of rearing. The LP birds were similar in BW to the R10 birds at 28 wk of age. By 40 wk of age, growth curves of all treatments became similar, with the R20 group having lower BW. Feed restriction reduced frame size during rearing. Flock uniformity in the R10 and R20 treatment hens was reduced during rearing, but improved early in the breeder period. Feed restriction reduced breast muscle and abdominal fat pad weight early in lay, except for the LP group. Liver lipid content increased throughout the breeder period. Changes in liver weight followed the pattern of BW changes. Total carcass protein content changes in time reflected breast muscle mass changes. In R20 hens, carcass lipid content was reduced and protein content increased. Sexual maturity was delayed in the R20 hens. Body weight at first egg was negatively correlated with settable egg production (r = –.37, P ≤ .0015). The R20 treatment is recommended for male-line turkey breeder hen candidates during rearing.

Effects of Increased Rearing Period Body Weights and Early Photostimulation on Broiler Breeder Egg Production ,

Broiler breeder pullets were subjected to photostimulation (PS) at either 14, 17, or 20 wk of age after attaining greater than recommended BW during rearing in order to determine effects on age at onset of lay, egg weight, and egg production. During rearing, feed was consumed ad libitum (AL) or provided in allotments resulting in growth to projected BW of 2.8 (heavy, HV) or 2.3 kg (light, LT) at 20 wk. Rearing period feeding and age at PS treatments made up a 3 × 3 factorial arrangement. A single restricted feeding program was provided during lay.Although age at first egg in the AL treatment was earlier than in HV and LT treatments, total production by HV and LT birds was greater because peak and postpeak production by AL birds were depressed. Relative to PS at 20 wk, PS at 14 and 17 wk advanced age at first egg and increased cumulative production to 30 wk. However, early PS decreased peak production and, therefore, did not affect total production. Mean egg weight and settable egg production (egg weight > 50 g) were increased in HV and LT treatments. Egg weight and settable egg production were not affected by age at PS. These results indicate that the onset of lay by broiler breeders can be advanced by early PS and that increased BW facilitates this. However, allowing greater BW during rearing does not compensate for reduced early egg weights and results in decreased total production and mean egg weights when feed is provided at recommended levels during lay.