Timing of growth affected broiler breeder feeding motivation and reproductive traits

Effects of metabolizable energy intake and body weight restriction on layer pullets: 2 - Body composition and onset of lay

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.

Body weight optimization of broiler breeder hens. 1. Pullet growth, feed efficiency, carcass composition, and sexual maturation

This study aimed to evaluate the effect of early growth (EG) and time of maximum pubertal growth peak (I2) on development, feed efficiency, carcass composition, and sexual maturation of broiler breeder females. Target BW trajectories were designed by changing coefficients of a 3-phase Gompertz model fit to the recommended BW target of Ross 308 breeders, [Formula: see text] . In each phase i, biologically relevant coefficients describe the amount of BW gain (gi), the rate of growth (bi), and the inflection point (Ii), which is the time when the growth rate for that phase is at its maximum rate. The study consisted of a 6 × 2 factorial arrangement, with six I2 levels (I from phase 2) and two EG levels. The I2 coefficients were 15, 17, 19, 21 (standard), 22, and 23 in wk. The EG treatments were: EG0, where g1 and g2 coefficients estimated from the standard from the breeder recommended BW were unchanged; and EG20, where 20% of the gain (g2) in phase 2 (pubertal phase) was shifted to phase 1 (g1; prepubertal phase). Two-hundred-eighty-eight Ross 308 pullets were randomly assigned to the twelve BW growth trajectories and fed using a precision feeding system from 0 to 28 wk of age. Body composition variables were submitted to three-way ANOVA, with EG, I2, and age as fixed sources of variation. Analysis of covariance was conducted on the remaining dependent variables with EG as fixed effect, I2 as a continuous fixed effect, and age as continuous random effect. Differences were reported at P ≤ 0.05. The BW of females followed their target BW, and ADFI differed depending on the amount of feed required to achieve their respective BW targets. Breast fleshing score was 0.2 greater in the EG20 compared to EG0. The number of juvenile primary wing feathers and age at first egg decreased by 0.4 and 0.9 d, respectively, per wk of earlier I2. Advancing I2 resulted in birds with increased carcass fat deposition from 16 to 28 wk of age. Carcass fat was 1.3- to 1.6-fold greater in the EG20 only from 4 to 16 wk of age. Early growth increased mostly pullet muscle and skeletal characteristics whereas advancing I2 advanced sexual maturity and increased carcass fat deposition around sexual maturation time.

Physiological role of dietary energy in the sexual maturity: clues of body size, gonad development, and serum biochemical parameters of Chinese indigenous chicken

Sexual maturity is a crucial factor in the formation and development of poultry reproductive capacity. The nutritional status has been confirmed to play an important role in the regulation of sexual maturity. To investigate the effect of dietary energy levels on sexual maturity in chicken, diets with 3 energy levels (group L: 2,573 kcal/kg, group C: 2,836 kcal/kg, group H: 3,122 kcal/kg) were implemented to feed Guangyuan Gray chickens. During this trial, body weight, body size, organ development, sexual maturity, reproductive performance and blood biochemical parameters were monitored. The earlier sexual maturity was observed in group H, as well as a heavier first egg weight, larger interpubic distance and higher total cholesterol (T-CHO) content at sexual maturity. The dietary energy levels had no significant effect on body weight at first egg and egg production at 300 d of age. Although dietary energy levels had a significant effect on body weight, comb length, tibia length and girth, abdominal fat weight, oviduct weight and length, T-CHO, triglyceride (TG) content and estradiol (E2) level during the rearing period. No significant difference of gonadotropin releasing hormone (GnRH) and luteinizing hormone (LH) level among 3 groups was observed during the trial. The dietary energy levels had effects on mRNA expression of GnRH, estrogen receptor 1 (ESR1), estrogen receptor 2 (ESR2) in hypothalamus, gonadotropin inhibitory hormone receptor (GnIHR) in pituitary and luteinizing hormone receptor (LHR), ESR2 in ovary. The GnIHR/GnRHR ratio in pituitary was higher before sexual maturity and decreased at sexual maturity. The results of correlations analysis found that all the body size, carcass traits, serum biochemical parameters negatively correlated with age at first egg except for interpubic distance and serum blood glucose content. Collectively, dietary energy levels had effects on sexual maturity of chicken, which may be achieved by affecting body weight, gonad development, endocrine and the mRNA expression of genes related to hypothalamus-pituitary-gonad axis. These results further set our understanding of how dietary energy regulates sexual maturity.

Is relaxing broiler breeder growth restriction cost-effective?

Broiler breeders are subjected to feed restriction programs to control excessive growth. However, current levels of feed restriction and concomitant growth restriction are becoming severe, raising welfare and suboptimal reproductive performance concerns in underfed breeders. To circumvent the issue, our previous studies investigated the effects of new strategic growth curves, with various degrees of relaxed growth restrictions, on broiler breeders and their progeny's performance. The broiler breeder study was conducted with 40 Ross 708 broiler breeder pullets reared on 1 of 10 target growth trajectories using a precision feeding (PF) system. The growth trajectories were designed with 2 levels of the amount of prepubertal BW gain and 5 levels of pubertal growth timing. The prepubertal BW gain (g1) was estimated from the breeder-recommended standard BW gain (Standard g1) target, or 10% higher (High g1). The pubertal growth timing (I2) was advanced such that it happened at I2-0% = 22.29 wk, I2-5% = 21.16 wk, I2-10% = 20.05 wk, I2-15% = 18.94 wk, I2-20% = 17.82 wk of age. Two broiler experiments with different maternal ages (35 and 42 wk) were conducted as the extension of the breeder experiment to evaluate the intergenerational effects of a reduced degree of maternal prepubertal phase growth restriction and earlier maternal pubertal phase growth on offspring growth and development. The current paper investigated the economic aspects of implementing the growth curves using the partial budget analysis. Increasing prepubertal BW gain by 10% and advancing the pubertal growth phase by 20% (scenario 10) could increase margin over feed and chick cost for the hatching egg producers by CDN$1.97/hen. For broiler chicken supply chain as a whole, the highest differential margin over feed and chick cost was for maternal growth scenario 10 from 42-wk-old hens. The latter margin over feed and chick cost was greater than that of breeder-recommended maternal growth (from 35-wk-old hens) by $0.1053/kg live chicken under the current economic situation.

Quantitative proteomics study on the changes of egg white of yellow preserved primary chicken eggs soaked in alkali solution

In order to investigate the changes of egg white of primary chicken eggs after being soaked in alkali solution, the tandem mass tags (TMT)-labeled quantitative proteomic technology combined with bioinformatics was conducted in this study. The results indicated that 100 differentially expressed proteins (DEPs) in yellow preserved primary egg white (YPPEW), 75 of which were highly and significantly correlated with the quality traits of YPPEW (| r | ≥ 0.9000, P < 0.01). Most of DEPs were involved in cellular processes by binding in extracellular space. Six pathways revealed the potential anti-inflammatory, anti-virus, anti-cancer and neuromodulatory mechanism of YPPEW. The current research provided a theoretical basis for the further study on YPPEW.

Welfare of broilers on farm

This Scientific Opinion considers the welfare of domestic fowl (Gallus gallus) related to the production of meat (broilers) and includes the keeping of day-old chicks, broiler breeders, and broiler chickens. Currently used husbandry systems in the EU are described. Overall, 19 highly relevant welfare consequences (WCs) were identified based on severity, duration and frequency of occurrence: 'bone lesions', 'cold stress', 'gastro-enteric disorders', 'group stress', 'handling stress', 'heat stress', 'isolation stress', 'inability to perform comfort behaviour', 'inability to perform exploratory or foraging behaviour', 'inability to avoid unwanted sexual behaviour', 'locomotory disorders', 'prolonged hunger', 'prolonged thirst', 'predation stress', 'restriction of movement', 'resting problems', 'sensory under- and overstimulation', 'soft tissue and integument damage' and 'umbilical disorders'. These WCs and their animal-based measures (ABMs) that can identify them are described in detail. A variety of hazards related to the different husbandry systems were identified as well as ABMs for assessing the different WCs. Measures to prevent or correct the hazards and/or mitigate each of the WCs are listed. Recommendations are provided on quantitative or qualitative criteria to answer specific questions on the welfare of broilers and related to genetic selection, temperature, feed and water restriction, use of cages, light, air quality and mutilations in breeders such as beak trimming, de-toeing and comb dubbing. In addition, minimal requirements (e.g. stocking density, group size, nests, provision of litter, perches and platforms, drinkers and feeders, of covered veranda and outdoor range) for an enclosure for keeping broiler chickens (fast-growing, slower-growing and broiler breeders) are recommended. Finally, 'total mortality', 'wounds', 'carcass condemnation' and 'footpad dermatitis' are proposed as indicators for monitoring at slaughter the welfare of broilers on-farm.

Fast growing broiler production from genetically different pure lines in Turkey. 2. Broiler traits: growth, feed intake, feed efficiency, livability, body defects and some heterotic effects

The aim of the this study was to reveal the trends in body weight (BW), feed intake (FI), feed conversion ratio (FCR), livability, and body defects (foot pad dermatitis (FPD), hock burn (HB), and breast burn (BB)) in offspring of ANADOLU-T pure lines (PLs), their 12 four-way hybrids and ROSS-308 hybrid, and the observed heterosis values for some performance and body defect traits. A total of 2736 (1368 broilers each) broiler chickens from ANADOLU-T pure lines, their hybrids, and commercial ROSS-308 hybrid were hatched from breeder eggs at 32 and 52 weeks of age and reared for 42 days in 2 experiments. The PL eggs were generally heavier than hybrid eggs (P < 0.001) and day-old BWs (P < 0.001) were also higher in PL chicks (ranging between 44.5 and 45.8 g). The males of ROSS-308 hybrid were heavier than others at 42 d of age (P = 0.035), and the lowest BW values were determined for A1, A2, and A3 line chickens (P < 0.001). ROSS-308 (4453.8 g) showed similar 42-d FI with all of four-way ANADOLU-T hybrids except (B1 × B2) × (A1 × A2) and (B1 × B2) × (A3 × A1). The 42-d FCR was 1.473 for the ROSS-308, while it ranged between 1.654 and 1.715 for the four-way ANADOLU-T hybrids (P < 0.001). The 42-d livability of four-way ANADOLU-T hybrids and ROSS-308 ranged between 92.0 and 100.0%. All ANADOLU-T hybrids, except two, showed higher 42-d livability than ROSS-308. While both genotype and sex were important for HB and BB, only the genotype effect was significant for FPD (P < 0.001). All ANADOLU-T hybrids showed low to moderate and positive heterosis for BW after 28 d. From 14 to 42 d, the magnitudes of heterosis for FCR decreased. Heterosis for livability from 7 to 42 d were not significant between genotypes. Percentages of heterosis for resistance to FPD (- 1.56 to 1.44%), HB (- 37.03 to 18.75%), and BB (- 12.70 to 1.02%) defects were not significant among genotypes. It was concluded that mating of B1 × B2 males with A1 × A2 and A3 × A2 females seems more favorable in terms of higher chick and meat production. However, the fact that the overall performance of ANADOLU-T hybrids is lower than ROSS-308 clearly indicates that genetic selection must be maintained for enhanced body weight and feed efficiency.

Fast growing broiler production from genetically different pure lines in Turkey. 1. Parental traits: growth, feed intake, reproduction, and hatching traits

The aim of the present study was to reveal the trends in age-related growth, feed intake, reproduction, and hatchability traits in 5 pure line (PL) breeders (3 dam [A1: slow-feathering, A2: fast-feathering, A3: slow-feathering] and 2 sire [B1: fast-feathering, B2: fast-feathering]) and their reciprocal two-way cross parent stock (PS) breeders (6 female [A1♂ × A2♀; A1♂ × A3♀; A2♂ × A1♀; A2♂ × A3♀; A3♂ × A1♀; A3♂ × A2♀] and 2 male [B1♂ × B2♀; B2♂ × B1♀]) and to identify heterotic effects in two-way cross PS combinations showing superiority over PL breeders. In the rearing period, 60 females and 15 males in the each PL group, 120 females in each female PS and 120 males in each male PS breeders, and 40 females and 5 males were used in each PL and PS genotype in the laying period. Body weight (BW), average daily feed intake (ADFI), reproductive traits (age at first egg [AFE], age at sexual maturity [ASM], egg number, weekly and total %Lay, egg weight, egg mass), hatching traits (fertility, hatchability of fertile [HOF] and set [HOS] and embryonic mortality), and heterosis (%) values for some traits were assesed. Both males and females of PLs and PSs had different BW at 4 and 8 weeks of age (P < 0.01), but had similar BW from 12 to 24 weeks of age. The A2, B1, and B2 hens had a higher BW (nearly 4000 g) than the others at 31 weeks of age (P < 0.01), and B2 hens showed a BW of more than 5000 g at 64 weeks (P < 0.001). Weekly ADFI per female in rearing, laying, and overall period was not different between groups. The A1 (179 days), A3 (183 days), two-way cross (from 175.5 to 185.5 days) hens started laying at a similar age and earlier than B1 (184 days), A2 (192 days), and B2 (194 days) hens. From AFE to 64 weeks, %Lay was the highest in the A1 line (69.7%), lowest in the B1 (45.3%) and B2 (48.8%) line, and between 56.9 and 64.8% in PS breeder hens. The PS eggs tended to have higher fertility, HOF, and HOS, and less embryonic mortality compared to PL eggs. Negative and low heterosis for AFE was observed in PS eggs, while positive heterosis for fertility, HOF, and HOS was generally observed in four-way hybrid eggs. The highest heterosis for the 64-week cumulative egg number was observed in A3 × A2 hens. Our study results show that mating of B1 × B2 males with A3 × A2 females seems more favorable in terms of higher egg or chick production. However, more knowledge is also needed for the overall efficiency of each PS, including the final performance of its hybrids.

Maternal supplementation of different trace mineral sources on broiler breeder production and progeny growth and gut health

Trace mineral minerals Zn, Cu, and Mn play important roles in breeder production and progeny performance. The objective of this study was to determine maternal supplementation of trace mineral minerals on breeder production and progeny growth and development. A total of 540 broiler breeders, Cobb 500 (Slow feathering; 0-66 weeks old) were assigned to one of three treatment groups with the same basal diet and three different supplemental trace minerals: ITM-inorganic trace minerals in sulfates: 100, 16, and 100 ppm of Zn, Cu, and Mn respectively; MMHAC -mineral methionine hydroxy analog chelate: 50, 8, and 50 ppm of bis-chelated MINTREX®Zn, Cu and Mn (Novus International, Inc.), and TMAAC - trace minerals amino acid complex: 50, 8, and 50 ppm of Zn, Cu, and Mn. At 28 weeks of age, eggs from breeder treatments were hatched for progeny trial, 10 pens with 6 males and 6 female birds per pen were fed a common diet with ITM for 45 days. Breeder production, egg quality, progeny growth performance, mRNA expression of gut health associated genes in breeder and progeny chicks were measured. Data were analyzed by one-way ANOVA; means were separated by Fisher's protected LSD test. A p-Value ≤ 0.05 was considered statistically different and 0.1 was considered numerical trend. Breeders on ITM treatment had higher (p < 0.05) body weight (BW), weight gain and lower (p < 0.05) feed conversion ratio (FCR) from 0 to 10 weeks, when compared to birds fed MMHAC. MMHAC significantly improved egg mass by 3 g (p < 0.05) and FCR by 34 points (0.05 < p < 0.1) throughout the reproductive period (26-66 weeks) in comparison to ITM. MMHAC improved (p < 0.01) egg yolk color versus (vs.) ITM and TMAAC in all periods, except 28 weeks, increased (p < 0.01) eggshell thickness and resistance vs. TMAAC at 58 weeks, and reduced (p < 0.05) jejunal NF-κB gene expression vs. TMAAC at 24 weeks. There was a significant reduction in tibial dry matter weight, Seedor index and resistance for the breeders that received MMHAC and/or TMAAC when compared to ITM at 18 weeks. Lower seedor index but numerically wider tibial circumference was seen in hens fed MMHAC at 24 weeks, and wider tibial circumference but lower tibial resistance in hens fed TMAAC at 66 weeks. Maternal supplementation of MMHAC in breeder hens increased (p < 0.0001) BW vs. ITM and TMAAC at hatching, reduced (p < 0.05) feed intake vs. ITM at d14 and d28, and improved (p < 0.01) FCR and performance index vs. TMAAC at d28, reduced (p < 0.01) NF-κB gene expression and increased (p < 0.05) A20 gene expression vs. TMAAC on d0 and vs. ITM on d14, reduced (p < 0.05) TLR2 gene expression vs. ITM on d0 and vs. TMAAC on d14, increased (p < 0.05) MUC2 gene expression vs. both ITM and TMAAC on d45 in progeny jejunum. Overall, these results suggest that supplementation with lower levels of MHA-chelated trace minerals improved breeder production and egg quality and reduced breeder jejunal inflammation while maintaining tibial development in comparison to those receiving higher inorganic mineral supplementation, and it also carried over the benefits to progeny with better growth performance, less jejunal inflammation and better innate immune response and gut barrier function in comparison to ITM and/or TMAAC.

Architecture of broiler breeder energy partitioning models

A robust model that estimates the ME intake over broiler breeder lifetime is essential for formulating diets with optimum nutrient levels. The experiment was conducted as a randomized controlled trial with 40 Ross 708 broiler breeder pullets reared on 1 of 10 target growth trajectories, which were designed with 2 levels of cumulative BW gain in prepubertal growth phase and 5 levels of timing of growth around puberty. This study investigated the effect of growth pattern on energy efficiency of birds and tested the effects of dividing data into daily, 4-d, weekly, 2-wk, and 3-wk periods and the inclusion of random terms associated with individual maintenance ME and ADG requirements, and age on ME partitioning model fit and predictive performance. Model [I] was: MEI_d = a × BW^b + c × ADG_p + d × ADG_n + e × EM + ε, where MEI_d was daily ME intake (kcal/d); BW in kg; ADG_p was positive ADG; ADG_n was negative ADG (g/d); EM was egg mass (g/d); ε was the model residual. Models [II to IV] were nonlinear mixed models based on the model [I] with inclusion of a random term for individual maintenance requirement, age, and ADG, respectively. Model [II] – 3 wk was chosen as the most parsimonious based on lower autocorrelation bias, closer fit of the estimates to the actual data (lower model MSE and closer R² to 1), and greater predictive performance among the models. Estimated ME partitioned to maintenance in model [II] – 3 wk was 100.47 ± 7.43 kcal/kg^0.56, and the ME requirement for ADG_p, ADG_n, and EM were 3.49 ± 0.37; 3.16 ± 3.91; and 2.96 ± 0.13 kcal/g, respectively. Standard treatment had lower residual heat production (RHP; -0.68 kcal/kg BW^0.56) than high early growth treatment (0.79 kcal/kg BW^0.56), indicating greater efficiency in utilizing the ME consumed. Including random term associated with individual maintenance ME in a 3-wk chunk size provided a robust, biologically sound life-time energy partitioning model for breeders.