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Percentage of Lohmann LSL lite (W) and Brown lite (B) birds reared under 3 feeding trajectories: ad libitum (AL), breeder’s recommended target (T) and Restricted (R) in lay.
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Recent studies showed that apart from photostimulation, metabolic triggers may independently activate sexual maturation and egg production in chickens. However, the origin, mode of action, and specific target(s) of this metabolic control remain unknown. Beyond body weight (BW), we hypothesize that body composition (BC) and associated specific metab...
Citations
... Poultry Science 104 (2025) 104640 first egg in the feed restricted pullets might be related to the metabolic status of the birds. Similar with the current study, age at sexual maturation was delayed in feed restricted laying hens when compared to ad libitum-fed birds (Johnson et al., 1984;Summers et al., 1991;Hao et al., 2019;Bahry et al., 2023;Muir et al., 2024). Several thresholds for sexual maturation have been proposed over the years: age (hypothalamic maturation), photoperiod, BW, and metabolic status (Lewis et al., 1994;Lewis et al., 2007;Hanlon et al., 2020). ...
... Hadinia et al. (2020) found that increasing energy intake of broiler breeders after the time of photostimulation (489 kcal/d vs. 258 kcal/d) increased the percentage of birds that commenced laying (100 % vs. 30 % at 26 wk of age), increased lipid deposition, and advanced the activation of the HPG axis from 22 to 26 wk of age. Additionally, the hypothesis that a minimum fat deposition is required for adequate sexual maturation in chickens has been suggested in broiler breeders (van Emous et al., 2013;van der Klein et al., 2018;Afrouziyeh et al., 2021) but also considered in laying hens (Bahry et al., 2023), which might indicate that birds with greater dietary ME intake (feed quantity or dietary ME level) achieved the fat threshold earlier than feed and energy restricted birds. In the current study, both dietary ME intake and body fat deposition were greater in the MEV-and ad libitum-fed birds, and in the High ME treatments as shown by Noetzold et al. (2023) and Tables 2 to 5, respectively. ...
... On the other hand, feed restriction appears to have greater influence in the early stages of ovary and follicular development when compared to the dietary energy factor. Ovary morphology has been widely reported to differ between ad libitum-fed and feed restricted broiler breeders (Renema et al., 1999;Hocking and Robertson, 2000;Renema and Robinson, 2004;Chen et al., 2006) and laying hens (Bahry et al., 2023). In the current study, feed restriction was the only factor affecting ovary morphology in egg-laying birds from 18 to 30 wk of age. ...
This study aimed to determine the effects of dietary ME and BW restriction on layer pullet sexual maturation, carcass composition and reproductive organs. Two trials were conducted: a precision feeding (PF) (Experiment 1) and a conventional (CON) experiment (Experiment 2). Experiment 1 was a 2 × 4 factorial arrangement with two feed allocation (FA) levels: meal every visit (MEV) or restricted to the lower limit of Lohmann Brown-Lite recommended BW; and three dietary ME levels: Low, Standard (Std), and High (2,600, 2,800, and 3,000 kcal/kg, respectively); the fourth treatment enabled birds to choose from the three diets (Choice). Experiment 2 was a 2 × 3 factorial arrangement with two FA levels: ad libitum or restricted to the lower limit of the strain recommended BW; and three dietary ME levels: Low, Std, and High. In Experiment 1, age at first egg (AFE), BW at first egg (BWFE), and carcass composition estimations were recorded. In Experiment 2, age at 50 % of egg production (A50), BW at 50 % of egg production (BW50), and chemical carcass composition were determined. Weight of reproductive organs were measured only in Experiment 2. Data were submitted to ANOVA on each experiment with the two main effects and age as fixed factors. Differences were reported where P ≤ 0.05. The BWFE and BW50 were greater in the MEV- and ad libitum-fed compared to the feed restricted birds in Experiments 1 and 2, respectively. Carcass lean and fat percentage were greater and lower in the feed restricted compared to the MEV- and ad libitum-fed pullets at 20 and 18 wk of age, respectively. Carcass fat percentage around photostimulation age (18 and 20 wk) was greater in the High ME compared to the Low ME fed pullets. Large yellow follicles (number and weight) and ovary (weight and percentage) were greater in ad libitum-fed compared to feed restricted birds. In conclusion, pullets fed greater dietary ME increased fat deposition and feed restricted birds had delayed sexual maturation.
... Management and nutrition have major effects on improving the health and development of pullets leading to enhanced uniformity, sexual maturation, body weight, and efficient feed utilization (Bahry et al., 2023). The objective of the rearing period is to achieve a flock with uniform sexual development with the proper body conformation to enable a more efficient transition to the laying period (Zuidhof et al., 2015). ...
... Estradiol and progesterone were the two main types of steroid hormones, primarily synthesized by the granulosa cells and theca cells of the follicle (Xiao et al., 2019). Previous studies showed significant fluctuations in E2 and progesterone levels in chicken serum pre-and post-sexual maturity (Hrabia et al., 2011;Bahry et al., 2023). Cholesterol, sourced mainly from plasma lipoproteins, serves as a crucial precursor for steroid hormone synthesis (Dong and Tong, 2019). ...
To deeply understanding the impact of peripheral energy level on the development of ovaries during the sexual maturation of chicken, in this study, the ovaries and serum of sexually mature and immature chickens at the same age from different energy level groups were collected, and the proteome and metabolome were detected. The results of ovarian and serum metabolomics revealed that dietary energy levels affected the energy metabolism and fatty acid oxidation of ovary in chicken, including the up-regulated expression of dihydroacetone phosphate and α-linolenic acid in high energy level groups. The results of proteomics showed that peripheral energy levels affected the catecholamine biosynthesis and metabolism in ovary before sexual maturation. The integrating analysis revealed that increased energy flux may influence ovarian development by regulating cholesterol reserves and steroid hormone synthesis in the ovaries. In vitro, the cultivation of chicken primary granulosa cells showed that sterol carrier protein 2 played a role in fatty acid synthesis and metabolism but did not significantly affect progesterone synthesis. Overall, dietary energy levels may be involved in the development of the ovaries during sexual maturation by influencing energy metabolism, biosynthesis of unsaturated fatty acids and steroid hormone within the ovaries.
... These have included assessment with the White Leghorn [13], Babcock ISA White [14], and Rugao [15]. Most recently, Bahry et al. [16] managed the FI of White and Brown Lohmann birds from 8-25 weeks of age (WOA) to achieve 80% target BW, which also delayed their AFE compared to ad libitum-fed birds. However, the impact of managing FI during rearing on current Hy-Line Brown pullets at the end of rearing and their AFE and EP through peak lay has not been evaluated and is a focus of the current study. ...
... In contrast, Balnave [12] found restricted feeding during rearing generated higher EP as the result of higher peak ROL and a slower decline in EP. However, egg production can vary with bird strain [16], which may have contributed to the higher EP observed with the earlier strains of hens following feed restriction during rearing [11,12] as opposed to the higher EP with ad lib feeding during rearing of current egg-laying hens. ...
As hen body weight (BW) impacts egg weight (EW) and feed efficiency, egg producers prefer pullets of a specific size to enter the egg-laying cycle. Lighting and feeding programs were tested to achieve target Hy-Line Brown pullet BW. Three feeding programs were implemented: ad libitum (ad lib); feeding to achieve breed standard weight for age (BSW); and feeding to achieve 88% BSW (managed). The feeding programs were used with either control lighting (CL: 10 h light/d from 7 weeks of age (WOA)) or reduced lighting (RL: 9 h light/d from 4 WOA). One-hundred and fifty pullets were assigned to each feeding program by lighting treatment during rearing. At 16 WOA, 70 pullets from each treatment during rearing were moved to cages and onto ad libitum feeding under a step-up photoperiod reaching 16 h light/d at 33 WOA. The age and weight of the first egg, hen BW, feed intake (FI), egg production (EP), and EW were measured until 36 WOA. At 16 WOA, pullets reared with ad lib feeding under CL had higher BW and cumulative FI (CFI) compared to ad lib feeding under RL. The latter were the earliest to lay, and the managed pullets under CL were the last to lay. Control lighting and BSW independently generated the heaviest first eggs. At 36 WOA, BW, EW, CFI, and cumulative egg production (CEP) were highest following ad lib feeding during rearing, while rearing under CL generated higher BW and EW but lower CEP than RL. Hence, lighting and feeding programs throughout rearing can regulate pullet growth, FI, and hen performance throughout early lay.
... Thess have included assessment with the White Leghorn [13], Babcock ISA White [14] and Rugao [15]. Most recently Bahry et al. [16] managed the FI of White and Brown Lohmann birds from 8-25 weeks of age (WOA) to achieve 80% target BW which also delayed their AFE compared to ad libitum fed birds. However, the impact of managing FI during rearing on current Hy-Line Brown pullets at the end of rearing, their AFE and EP through peak lay have not been evaluated and is a focus of the current study. ...
... To the contrary, Balnave [12] found restricted feeding during rearing generated higher EP, being the result of higher peak ROL and a slower decline in EP. But egg production can vary with bird strain [16], which may contribute to the higher EP observed with the earlier strains of hens following feed restriction during rearing [11,12] as opposed to the higher EP with Ad lib feeding during rearing of current egg-laying hens. ...
As hen body weight (BW) impacts egg weight (EW) and feed efficiency, egg producers prefer pullets of a specific size to enter the egg-laying cycle. Lighting and feeding programs were tested to achieve target pullet BW. Three feeding programs: Ad libitum (Ad lib); feeding to achieve breed standard weight for age (BSW); feeding to achieve 88% BSW (managed) were used with either control lighting, (CL: 10h light/d from 7 weeks of age (WOA)) or reduced lighting (RL: 9h light/d from 4 WOA). At 16 WOA pullets moved to cages and ad libitum feeding under a step-up photoperiod reaching 16h at 33 WOA. The age and weight of first egg, BW, feed intake (FI), egg production (EP) and EW were measured until 36 WOA. At 16 WOA, pullets reared with Ad lib feeding under CL had higher BW and cumulative FI (CFI) compared to Ad lib feeding under RL. The latter were the earliest and managed pullets under CL the latest, to lay. Control lighting and BSW independently generated the heaviest first eggs. At 36 WOA, BW, EW, CFI and CEP were highest following Ad lib feeding during rearing while CL generated higher BW and EW but lower CEP than RL. Hence lighting and feeding programs throughout rearing can regulate pullet growth and, hen performance throughout early lay.
... Animal growth typically exhibits a parabolic (power) pattern, consisting of exponential and S-shaped growth, which usually includes a rapid growth phase during the juvenile and adolescent stages, followed by a stable phase spanning from mature to old age (Zotin, 2015). In breeding programs for egglaying chickens, BW at sexual maturity serves as an important indicator because of its significant impact on subsequent egg production (Bahry et al., 2023). In addition, excessive BW during the late laying period leads to a decrease in egg production (Kirikci et al., 2007). ...
... Previous studies have found that dietary energy has an important regulatory role in gonadal development and estrogen secretion in birds [34][35][36]. Restricted feeding trials with hens have shown that a slowdown in growth delayed the age at egg laying [37]. In addition, in avian species, lipids, especially triglycerides, are involved in the sexual maturation of hens [38]. ...
Citation: Zhou, X.; Xu, Y.; Fang, C.; Ye, C.; Liang, W.; Fan, Z.; Ma, X.; Liu, A.; Zhang, X.; Luo, Q. Integrated Transcriptomic-Metabolomic Analysis Reveals the Effect of Different Light Intensities on Ovarian Development in Chickens. Int. J. Mol. Sci. 2024, 25, 8704. https://doi. Abstract: Light is a key environmental factor regulating reproduction in avians. However, the mechanism of light intensity regulating ovarian development is still unclear. In this study, 5-week-old (5 wk) partridge broiler breeders were randomly divided into a low-light-intensity group (LL group) and a natural-light-intensity group (NL group) (n = 100). In the rearing period (5 wk to 22 wk), the light intensity of the LL group and NL group were 0.41 ± 0.05 lux and 45.39 ± 1.09 lux, and in the laying period (23 wk to 32 wk) they were 23.92 ± 0.06 lux and 66.93 ± 0.76 lux, respectively. Samples were collected on 22 wk and 32 wk. The results showed that the LL group had a later age at first egg and a longer laying period than the NL group. Serum P4 and LH levels in the LL group were higher than in the NL group on 22 wk (p < 0.05). On 32 wk, P4, E2, LH and FSH levels in the LL group were lower than in the NL group (p < 0.05). Ovarian transcriptomics and metabolomics identified 128 differentially expressed genes (DEGs) and 467 differential metabolites (DMs) on 22 wk; 155 DEGs and 531 DMs on 32 wk between two groups. An enrichment analysis of these DEGs and DMs identified key signaling pathways, including steroid hormone biosynthesis, neuroactive ligand-receptor interaction. In these pathways, genes such as CYP21A1, SSTR2, and NPY may regulate the synthesis of metabolites, including tryptamine, triglycerides, and phenylalanine. These genes and metabolites may play a dominant role in the light-intensity regulation of ovarian development and laying performance in broiler breeders.
... Yet, peculiarities of the pullet at the point of lay are that she is yet to attain mature body weight (BW), exhibits In recognition of the critical role of pullet condition at onset lay and the subsequent impact on flock performance, significant research has been completed on feeding programs for pullets. For example, energy and protein (amino acids) requirements to optimize body development and composition at the point of lay (Leeson and Summers, 1981;Atkinson et al., 1991;Keshavarz and Jackson, 1992;Bahry et al., 2023). Moreover, the intimate linkage between the skeletal integrity of laying hens and medullary bone calcium reserves at the point of lay has elicited tremendous interest in mineral nutrition (Hurwitz and Bar, 1971;Keshavarz, 1987;Khanal et al., 2019Khanal et al., , 2020aKhanal et al., , 2021. ...
There are limited investigations on the role of feed additives in easing transition of pullets to egg production phase. We investigated effects of supplementation of bacitracin methylene disalicylate (BMD) and select feed additives (myristic acid (MA), benzoic acid (BA), and Aspergillus Niger (PRO)) in feeding program for pullets from onset of lay through to 31 weeks of age (woa). Parameters measured included hen-day egg production (HDEP), feed intake (FI), feed conversion ratio (FCR), egg quality characteristics, ceca microbial activity, apparent retention of components, and plasma metabolites. A total of 1,200 Lohmann LSL Lite pullets were procured at 18 woa and placed in enriched cages (30 birds/cage) based on body weight (BW) and allocated to 5 diets. The diets were: a basal diet formulated to meet specifications or basal mixed with either BMD, MA, BA or PRO. Birds had free access to feed and water throughout the experiment. Between 18 to 20 woa, birds fed BMD ate a similar (P>0.05) amount of feed to BA birds, but more (P=0.0003) than birds fed basal, MA or PRO diets. Basal birds had lower HDEP (P=0.001), and lighter eggs (P<0.0001) than birds fed any of the feed additives between 21 and 31 woa. The basal hens had a higher (P=0.009) abundance of E. coli than birds fed BMD, BA, and PRO diets. Consequently, BMD, BA, and PRO birds had a higher (P=0.011) Lactobacillus: E. coli ratio (LER) than hens fed the basal diet. Specifically, relative to basal-fed hens, the LER ratio of the BMD, MA, BA, and PRO hens was higher by 37, 21, 26, and 45%, respectively. Moreover, birds fed PRO tended to have higher concentration of ceca digesta acetic acid (P=0.072) and lower concentration of isobutyric acid (P=0.096). In conclusion, supplementing pullet diets with broad spectrum antibiotic or feed additives (MA, BA, and PRO) had positive impact on feed intake, and egg production linked to modulation of indices of gut health. The results suggested feed additives in feeding programs for pullets at the onset of lay can bolster productivity outcomes.
... 잡종강세 효과는 Hy-Line Brown 등 이미 상용화된 종 자 개발에도 사용된 기법이다 (Rizzi, 2020 (Thiruvenkadan et al., 2010;Saibaba et al., 2021). 이러한 부분은 산란계의 사료 효율성, 사 육 비용, 수익성 및 전반적인 생산성과 직결되며, 산란계의 성성숙에도 영향을 미쳐 육성기 이후 산란기의 산란율과 계 란의 크기 등 중요한 요소에도 작용한다 (Whitehead, 2004;Pérez-Bonilla et al., 2012;Lu et al., 2021;Bahry et al., 2023;Giersberg and Rodenburg, 2023 (Zubair and Leeson, 1996;Onofri et al., 2021). 이는 타 교배조합 종에 비하여 CKCF, YCYD, YDYC가 비교적 산란계의 표준체중에 도달 하기까지 어려움이 적다는 점을 시사한다. ...
The current study was conducted to compare the effect of crossbred on the body weight and laying performance of Korean native chicken from hatch to week 40. A total of 873 one-day-old chicks were divided into twelve crossbreds (i.e., CFCK, CFYC, CFYD, CKCF, CKYC, CKYD, YCYD, YCCF, YCCK, YDCF, YDCK, and YDYC) and commercial layer (Hy-Line Brown) were obtained as a counterpart in the study. All the birds are raised in battery cages (76 × 61 × 46 cm3) and then raised until 14 weeks and subsequently moved to layer battery cages (60 × 25 × 45 cm3) and raised until 16 weeks. The body weight and viability were measured biweekly from hatching to week 16. The week of 16, body weight range was about 1,010.24 to 1,411.77 g. The body weight of specific crossbreeds (i.e., CKCF, YCYD, and YDYC) was found to be comparable to that of Hy-Line Brown). The viability hatch to week 14 range was about 55 to 100% and however week 14 to 16 range was 80 to 100%. The crossbred (i.e., CKCF) recorded superior (P<0.05) viability throughout the whole experiment period, even compared with Hy-Line Brown (100% vs 96%). Our results are indicating that crossbreds Korean native chicken including CKCF, and YDYC has the potential to enhance key features of laying hens during the growing phase like optimal body weight and higher viability.
... Restricted pullets have lower maintenance requirements, consuming less feed and being more efficient [11]. On the other hand, severe feed restriction during the rearing period can limit nutrient intake and decrease BW and egg production [12,13]. Additionally, restricted birds have increased lean mass deposition [14], which can further prevent birds from developing hemorrhagic liver syndrome [15], but also may decrease reproductive capacity. ...
... Egg-type pullets are known to have small BW difference when restricted-fed at 70% compared to ad libitum feeding by the time of photostimulation [32]. More recently, Bahry et al. [13] showed that Lohmann Brown-Lite pullets fed ad libitum had greater BW when compared to target-fed or those fed 20% below the target BW. In the above study, pullets were fed conventionally [13], similarly to the present study, where the CON experiment showed larger BW differences in the ad libitumvs. ...
... More recently, Bahry et al. [13] showed that Lohmann Brown-Lite pullets fed ad libitum had greater BW when compared to target-fed or those fed 20% below the target BW. In the above study, pullets were fed conventionally [13], similarly to the present study, where the CON experiment showed larger BW differences in the ad libitumvs. restricted-fed birds compared to the MEV-vs. ...
This study aimed to determine the effects of dietary energy and bodyweight (BW) restriction on layer pullets' growth, uniformity, and feed efficiency. Two experiments were conducted using a precision feeding (PF) system (Experiment 1) and a conventional feeding (CON) system (Experiment 2). Experiment 1 consisted of a 2 × 4 factorial arrangement (eight treatments) with two feed allocation (FA) levels: meal every visit (MEV) or restricted to the lower boundary of Lohmann Brown-Lite pullets; and three dietary metabolizable energy (ME) levels: Low, Standard (Std), and High (2600, 2800, and 3000 kcal/kg, respectively); the fourth treatment enabled birds to choose from the three diets (Choice). Experiment 2 consisted of a 2 × 3 factorial arrangement (six treatments): two FA levels (ad libitum or restricted) and three dietary ME levels (Low, Std, and High). In each experiment, BW, coefficient of variation (CV), average daily feed intake (ADFI), average daily metabolizable energy intake (MEI), and feed conversion ratio (FCR) were recorded. Diet ADFI preferences and feeding motivation were determined only in the PF experiment. ANOVA was conducted on each experiment with the two main effects as fixed factors (FA and dietary ME), and age or period as the sources of variation. Differences were reported at p ≤ 0.05. MEV (PF experiment) and ad libitum-fed (CON experiment) pullets had greater BW compared to restricted-fed pullets (p < 0.05). The lowest CV was observed in the restricted-fed pullets from the PF experiment (p < 0.05). ADFI was greater in pullets fed the Low ME diet in the PF experiment compared to all the other groups, and the lower the dietary ME, the greater the ADFI in the CON experiment (p < 0.05). Choice-feeding pullets preferred feed with greater ME content in the PF experiment (p < 0.05). The lower the dietary ME, the greater the FCR in the CON experiment (p < 0.05). Restricted-fed pullets had greater daily visits, and lower daily meals, meal size, and successful visits to the PF system (p < 0.05). In conclusion, the results of this trial indicated that lower dietary ME increased FCR and ADFI, whereas feed restriction decreased BW and increased feeding motivation. Future steps after this trial will include examining the effects of dietary energy and feed restriction on carcass composition and sexual maturation.
