The effect of alternative feeding strategies for broiler breeder pullets: 1. Welfare and performance during rearing

Cage-Free Pullets Minimally Affected by Stocking Density Stressors

Management choices during the pullet phase can affect behavior, welfare, and health later in life, but few studies have evaluated the pullet phase, particularly in extensive housing systems. This study was a 2 × 2 factorial randomized complete block design (RCBD) with two strains and two stocking densities. The Lohmann LB-Lite and Lohmann LSL-Lite were housed on the floor at high-stocking density (619-670 cm2/bird) and low-stocking density (1249-1352 cm2/bird), which changed with age from 2 to 16 weeks of age (WOA). Bird-based measures of appearance, blood parameters, organ measurements, and production values were evaluated. Stocking density alone affected (p < 0.05) only relative bursal weight (% of body weight)-3.32% in the low-density versus 3.08% in the high-density group. High-stocking density was correlated with decreased uniformity (high-89.33 ± 0.24%; low-90.41 ± 0.24; p < 0.02) and worse feather coverage in the brown strain. High-stocking density was correlated with greater uniformity (High-90.39 ± 0.24%; Low-88.47 ± 0.24%; p < 0.001) and better feather coverage in the white strain. This study's feed conversion ratio (FCR) was improved by 0.07 in the low-stocking density for both strains. The remaining parameters were affected by strain and age only. Thus, while stocking density effects vary slightly depending on the strain used, cage-free pullets had limited negative effects at both the high and low-stocking densities tested in this study; there were few to no changes in the numerous bird-based welfare parameters tested.

Response of broiler breeder pullets when fed hydrolyzed whole yeast from placement to 22 wk of age

The study examined the effects of feeding broiler breeder pullets hydrolyzed whole yeast (HY) from hatch to 22 wk of age (WOA). A total of 524-day-old Ross 708 pullets were placed in floor pens (∼24 birds/pen) for the starter (0-4 WOA) and grower (5-18 WOA) phases, then transferred to the egg production facility and redistributed to ∼20 birds/pen for the prelay phase (19-22 WOA). Two diets were allocated to pens (0-18 WOA; n = 11) and (19-22 WOA; n-12). The diets were a control corn and soybean meal diet formulated to meet specifications and control plus 0.05% HY (HY). Birds had ad libitum access to feed in the first week and daily feed allocation based on pen BW from 2 WOA. Birds had free access to water throughout the trial. Body weight (BW) and uniformity (BW CV) were monitored. Boosters for infectious bronchitis and New Castle disease vaccines were administered at 18 WOA, and samples of pullets bled for antibody titer 5-day later. One pullet/pen was randomly selected, weighed, bled for plasma biochemistry, and necropsied for organ weights, ceca digesta for short-chain fatty acids (SCFA), and leg bones morphometry. In the starter and grower phases, birds fed HY were lighter and gained less (P < 0.05) than control birds. However, there were no diet effects (P > 0.05) on growth, the BW prelay phase, or BW uniformity throughout the trial. There were no (P > 0.05) diet effects on breast, gastrointestinal, liver and bursa weights, serum antibody titers, plasma biochemistry, SCFA and bone attributes. However, pullets fed HY had heavier (P = 0.047) spleen and tended to have lower (P = 0.080) plasma concentrations of aspartate aminotransferase (AST) relative to control pullets. In conclusion, the parameters assessed showed no negative consequences of feeding HY to broiler breeder pullets. However, effects on the spleen and plasma AST may indicate modest modulation of immunity and metabolism. The impact of the provision of HY during broiler breeder pullet phase on reproductive performance and chick quality should be investigated.

Growth and response to Escherichia coli lipopolysaccharide challenge in Lohmann LSL-Lite pullets when fed a source of omega-3 fatty acids and yeast bioactives from hatch through to 16 wk of age

Growth and response to Escherichia coli lipopolysaccharide (LPS) challenge in Lohmann LSL-Lite pullets when fed a source of omega-3 fatty acids (n-3 FA) and yeast bioactives (YB) from hatch through to 16 wk of age (woa) were investigated. Co-extruded full fat flaxseed and pulse mixture (FFF; 1:1 wt/wt) supplied n-3 FA and YB were yeast cell walls processed with β-1,3-glucan hydrolase. A total of 1,064-day-old pullets were placed in cages (19 birds/cage) and allocated to 7 diets (n = 8). The iso-caloric and iso-nitrogenous diets were control, control + 1, 3, or 5% FFF and + 0.025, 0.05, or 0.1% YB. The birds had ad libitum access to feed and water. Body weight (BW), feed intake, and lymphoid organs weight were recorded. At 15 woa, 2 pairs of pullets/cage received intravenous injection of either 1 mL of sterile saline without or with 8 mg LPS/kg BW. Injected pullets were bled, monitored for BW and cloaca temperature at time points within 168 h. Birds fed 1% FFF were heavier (P < 0.04) than birds fed other diets at 16 woa with FFF and YB exhibiting non-linear responses. Control birds had heavier (P = 0.02) thymus at 4 woa. Spleen weight increased quadratically (P < 0.05) in response to FFF at 8 and YB at 16 woa. The LPS increased cloaca temperature and altered concentration of several plasma metabolites (P < 0.05). The interaction (P < 0.05) between LPS and diet was such that control birds exhibited lower creatine kinase (CK) upon challenge with LPS relative to birds fed other diets. The LPS birds fed 1% FFF and 0.05% YB showed higher plasma albumin than non-LPS cohorts. Non-LPS birds fed control, 1 and 3% FFF had higher plasma K than LPS cohorts. In general, FFF and YB exhibited linear and quadratic effects (P < 0.05) on select plasma metabolites. In conclusion, dietary provision of n-3 FA and YB influenced pullet BW at sexual maturity, development of lymphoid organs and modulated some plasma metabolites in response to LPS.

LED Light Applied to the Feeder: Impact on Growth Performances of Chickens under Productive Conditions

This study assessed the use of feeders equipped with light-emitting diodes and their effects on the productivity of broiler chickens under productive conditions. A total of 87,200 ROSS 308 chickens, 1-day old, were housed in two poultry houses (CONTROL, F-LED). In CONTROL, 20,000 females (mean body weight 41.12 ± 3 g) and 25,000 males (mean body weight 41.56 ± 3 g) were housed, while 19,200 females and 23,000 males of the same genetic make-up and mean body weight were housed in F-LED under the same environmental conditions. In F-LED, to encourage chickens to feed and to redistribute more feed down the feeding line, a feeder equipped with a LED light has been installed at the end of each line. In CONTROL, no light was located on the feeders. At the end of the cycle, the average body weight never showed significant differences both for females (1345 g in CONTROL; 1359 g in F-LED) and for males (2771 g in CONTROL; 2793 g in F-LED). Uniformity improved in F-LED, at 75.2% in females and 54.1% in males, compared to CONTROL, at 65.7% and 48.5%, respectively, for females and males. The feed conversion ratio followed the same trend, being more favorable in chickens reared in F-LED (1.567) compared to those raised in CONTROL (1.608). The application of a single F-LED at the end of each feeding line demonstrated its utility in improving size uniformity and feed conversion.

The Effects of Mild Disturbances on Sleep Behaviour in Laying Hens

The positive welfare of commercial animals presents many benefits, making the accurate assessment of welfare important. Assessments frequently use behaviour to determine welfare state; however, nighttime behaviours are often ignored. Sleep behaviour may offer new insights into welfare assessments. This study aimed to establish a baseline for sleep behaviour in laying hens and to then apply mild short-term disturbances and observe the subsequent effects. Twelve laying hens were divided into four batches and were surgically implanted with electroencephalogram (EEG) devices to record their brain activity. The batches were subjected to undisturbed, disturbed and recovery types of nights. Disturbed nights consisted of systematic sequences of disturbance application (wind, 90 dB noise or 20 lux light) applied one at a time for 5 min every 30 min from 21:00 to 03:00 (lights off period: 19:00-05:00). Sleep state was scored using EEG data and behaviour data from infrared cameras. Over all the types of night hens engaged in both SWS (58%) and REM sleep (18%) during lights off. When applied, the disturbances were effective at altering the amounts of wakefulness and SWS (Time × Type of Night, p < 0.001, p = 0.017, respectively), whereas REM sleep was unaltered (p = 0.540). There was no evidence of carry-over effects over the following day or night. Laying hens may be resilient to short-term sleep disruption by compensating for this in the same night, suggesting that these disturbances do not impact their long-term welfare (i.e., over days). Sleep behaviour potentially offers a unique means of assessing an aspect of animal welfare that, to date, has been poorly studied.

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.

Restricted feeding regimens improve white striping associated muscular defects in broiler chickens

The current study investigated the effects of intermittent feeding (IF) and fasting strategies at different times post-hatch on muscle growth and white striping (WS) breast development. In the first trial, 32 one-day-old Abor Acre broilers were fed ad libitum (AL) for 3 d post-hatch and then randomly allotted into 4 feeding strategies including AL, 1h-IF group (1 h IF, 4 times feeding/d, 1 h each time), 1.5h-IF (1.5 h IF, 4 times feeding/d, 1.5 h each time), and fasting (1d acute fasting, 6 d free access to feed) groups and fed for 7 d. Although angiogenic genes including VEGFA, VEGFR1, and VEGFR2, and myogenic genes including MYOG and MYOD were upregulated (P < 0.05), the breast muscle satellite cell (SC) number and PAX7, MYF5 expression were decreased by the IF strategies (P < 0.05). One-day fasting at 6 d of age also upregulated angiogenic genes and MYOD expression (P < 0.05), downregulated MYF5 expression (P < 0.05), but did not change SC number (P > 0.05). In the second trial, 384 one-day-old birds were fed AL for 1 wk and then randomly allotted to the above 4 feeding strategies starting at 8 d of age until 42 d of age. Similarly, IF and fasting strategies upregulated the expression of angiogenic and myogenic genes (P < 0.05). Both 1h-IF and 1.5h-IF increased breast muscle SC number (P < 0.05). At slaughter, breast muscle fiber diameter of 1.5h-IF was smaller but the SC number was larger than that of the birds fed AL (P < 0.05). The IF and fasting strategies prevented WS development, and reduced breast WS scores and triglyceride content (P < 0.05) without changing the body weight (P > 0.05). Fasting and 1h-IF reduced the expression of adipogenic genes ZNF423 and PDGFRα (P < 0.05). Moreover, IF and fasting strategies reduced fibrosis in breast muscle and reduced skeletal muscle-specific E3 ubiquitin ligases (TRIM63 and MAFBX) (P < 0.05). Fasting significantly reduced CASPASE-3 in breast muscle (P < 0.05). In conclusion, IF starting in the first week decreases SC number. Compared to AL, IF or fasting promotes muscular angiogenesis, increases SC number, prevents muscle degeneration, and prevents the development of WS without impairing the growth performance of broiler chickens.

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.

Feed Restriction Improves Lipid Metabolism by Changing the Structure of the Cecal Microbial Community and Enhances the Meat Quality and Flavor of Bearded Chickens

Excessive fat deposition in full-fed Bearded chickens does not only reduce carcass yield but also causes consumer rejection of meat. Feed restriction (FR) is an effective method to save on feed cost, reduce carcass fat deposition, and improve meat quality. A total of 560 150-d Bearded chickens were randomly divided into seven groups (each with eight replicates of ten birds) for 40 days. The control group was fed with the basal diet ad libitum (CON), and the other six groups were fed with 90% of the feed intake (90% FI), 80% FI, 70% FI, 90% metabolizable energy (90% ME), 80% ME, and 70% ME of the CON, respectively. Compared to the CON group, FR increased meat yield, but the total weight of the Bearded chickens was slighter; 80% FI and 70% ME improved the relative lipid metabolism indices of chickens, especially the levels of triglycerides and total cholesterol in the plasma and liver (p < 0.05), and decreased calpastatin activity in the breast muscle (p < 0.05). Additionally, 16S rRNA sequencing of cecal microbial community indicated that an increase in the abundance of Hydrogenoanaerobacterium and Bacteroides plebeius was observed in the 80% FI group (p < 0.05), and an enrichment in Olsenella, Catabacter, and Lachnospiraceae were observed in the 70% ME group (p < 0.05) compared to the CON group. Moreover, compared to the CON group, the L * value of the breast muscle significantly decreased, and a * value significantly increased in the 80% FI group (p < 0.05). Notably, the concentrations of threonine, lysine, aspartic acid, glutamic acid, proline, and arginine and the activity of calpain in breast muscle increased in the 80% FI group more than in the CON group (p < 0.05), while valine, isoleucine, leucine, phenylalanine, lysine, alanine, tyrosine and proline decreased in ME restriction groups (p < 0.05). Taken together, our results indicated that 80% FI could improve lipid metabolism by changing the structure of the cecal microbial community, and the meat quality and flavor of the Bearded chickens in 80% FI group was improved with a promoted meat color score, flavor substances, and the calproteinase system.

In Pursuit of a Better Broiler: Welfare and Productivity of Slower-growing Broiler Breeders during Lay

Current commercial strains of broiler breeders display reproductive dysregulation when fed to satiety, but they can achieve optimal hatching egg production under feed restriction. However, chronic feed restriction in broiler breeders is a welfare concern due to physiological and behavioral signs of hunger, lack of satiety, and frustrated feeding motivation. The purpose of this study was to assess the welfare and productivity of slower-growing broiler breeders during lay. A total of 336 broiler breeders from 5 strains of slower-growing broiler breeders (3 female strains: 100 hens per strain, and 2 male strains: 12 and 24 roosters per strain) were kept in 12 identical pens throughout lay, 4 pens per combination of roosters and hens: A hens with Y roosters, B hens with Y roosters, and C hens with X roosters. According to guidelines, strain B and C hens and X roosters were slower growing strains and strain A hens and Y roosters were intermediate growing strains. Egg production was recorded daily, and settable eggs laid at 30, 40, and 50 wk of age were incubated to hatch. Growth rate, feed and water intake, and welfare indicators (feeding motivation, behavior, and physical assessment: feather coverage, foot and leg health, and keel bone status) were recorded during lay. Additionally, a subsample of 5 hens per pen was dissected for anatomical analyses. Laying rate started and peaked earlier in B hens than in A hens and remained above 70% in both strains, yielding high cumulative egg production (>165 eggs/hen) until 53 wk of age. Until 50 wk of age, fertility and hatched of fertile was high in slower growing broiler breeders, on average, above 95 and 80%, respectively. Compared to A hens, B and C hens had better feather coverage, lower feeding motivation, and lower daily water and feed intake. Results of this study suggest that slower growing broiler breeders show reduced signs of poor welfare and improved productivity during lay although susceptibility to obesity-related problems on laying rate may be strain-specific.

Impact of broiler breeder growth trajectory on plasma corticosterone concentration: a comparison of analytical methods

Blood concentration of corticosterone (CORT) is a measure of welfare in feed restricted broiler breeders. The RIA and ELISA have been routinely used for measuring CORT in blood, excreta, and feather. Due to the presence of some confounding factors in the aforementioned colorimetric enzyme reaction methods, some methodological difficulties have been attributed to those assays. The correlation between broiler breeder plasma CORT concentrations, measured using ELISA and a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, was the focus of the current study. A total of 36 broiler breeder pullets were used, of which 30 were randomly assigned to one of 10 unique growth trajectories, and 6 were assigned to an unrestricted group. We designed the growth trajectories using a 3-phase Gompertz growth model with 10 levels of BW gain in the prepubertal and pubertal growth phases, ranging from the breeder-recommended target BW (CON) to 22.5% higher (CON+22.5%), in 2.5% increments. The BW trajectories were applied to each individual bird using a precision feeding (PF) system, which collected BW and feed intake data. The birds were classified based on age at first egg (AFE), and 12 birds each having the highest and lowest AFE was selected for the CORT study. Then median photostimulation BW of the candidate birds was used to define the upper (heavy BW) and lower (standard BW) extremes, and plasma CORT levels were evaluated by ELISA and LC-MS/MS methods from their blood collected at 18, 20, 22, 24, and 26 wk of age. Concentrations of plasma CORT measured using ELISA method were highly correlated (r = 0.95; P < 0.001) with values measured using LC-MS/MS method, validating interchangeably usage of both methods to measure plasma CORT in broiler breeders. Plasma CORT levels were not affected by photostimulation BW or breeders' age, indicating same welfare status between the precision fed high and low BW groups.

In Pursuit of a Better Broiler: Walking Ability and Incidence of Contact Dermatitis in Conventional and Slower-Growing Strains of Broiler Chickens

In this study, the mobility, incidence, and severity of contact dermatitis and litter moisture content were assessed in 14 strains of broiler chickens differing in growth rate. The strains encompassed 2 conventional (CONV; ADG_0-48 > 60 g/d) and 12 slower growing (SG) strains categorized as FAST (ADG_0-62 = 53-55 g/d), MOD (ADG_0-62 = 50-51 g/d), and SLOW (ADG_0-62 < 50 g/d), with 4 strains in each category. A total of 7,216 mixed-sex birds were equally allocated into 164 pens (44 birds/pen; 30 kg/m²) in a randomized incomplete block design, with each strain represented in 8 to 12 pens over 2–3 trials. From each pen, 4 to 6 birds were tested in the latency-to-lie (LTL) and group obstacle tests 1 wk prior to the birds reaching 2 target weights (TWs) of approximately 2.1 kg (TW1: 34 d for CONV and 48 d for SG strains) and 3.2 kg (TW2: 48 d for CONV and 62 d for SG strains). The incidence of footpad dermatitis (FPD) and hock burns (HB) were evaluated a day prior to each TW. Litter moisture content was determined biweekly from d 14 to d 56. At TW1, CONV and SLOW had longer LTL than FAST birds. At TW2, CONV, MOD, and FAST birds had similar LTL. At both TWs, CONV birds were lighter than FAST birds in the group obstacle test, yet their number of obstacle crossings was similar. At TW1, CONV birds had greater incidence of FPD than FAST and MOD, while at TW2, CONV birds had greater incidence than the other categories. The incidence of HB in CONV and MOD was greater than SLOW birds at TW1, while at TW2, the incidence of HB was greater in CONV and FAST birds vs. MOD and SLOW birds. Litter moisture content was high in all categories from d 28 onward. Our results indicate that both BW and growth rate influence leg strength and walking ability, whereas the overall high litter moisture content and to a lesser extent growth rate influenced the incidence of contact dermatitis.

Welfare and performance of slower growing broiler breeders during rearing

Current commercial strains of broiler breeders can only achieve an optimal reproductive performance under feed restriction. However, chronic feed restriction in broiler breeders is a welfare concern because of physiological and behavioral signs of hunger, lack of satiety, and frustrated feeding motivation. The objective of this research was to assess the welfare and performance of slower growing broiler breeders during rearing. A total of 360 broiler breeder chicks from 3 female strains (100 chicks per strain) and 2 male strains (20 and 40 chicks per strain) were raised in four identical pens per strain. Strain B and C pullets and X cockerels were slower growing strains, and strain A pullets and Y cockerels were intermediate growing strains. Birds were weighed and scored individually for footpad lesions, hock burns and feather coverage. Data were analyzed using generalized linear mixed models with pen nested in the models and age as a repeated measure. Compared to B and C pullets, strain A pullets grew faster, had poorer body weight uniformity, and started feed restriction 2 wk earlier to control growth rate. Strain A pullets also had higher feeding rate at 3 and 5 wk, higher water intake at 4 and 5 wk, and higher prevalence of footpad lesions at 6 wk than the other pullet strains. Fault bars in wing feathers (an indicator of chronic stress) were more numerous in A pullets than in B and C pullets. Our results indicate that pullets showed little feather coverage loss during early rearing and had good body weight uniformity and low cumulative feed intake at the end of rearing. Slower growing broiler breeders may still require some degree of feed restriction to control growth rate, and strains with lower feed restriction exhibited lower signs of feeding frustration and high body weight uniformity.

Body weight, organ development and jejunal histomorphology in broiler breeder pullets fed n-3 fatty acids enriched diets from hatch through to 22 weeks of age

Dietary long chain polyunsaturated n-3 fatty acids (n-3 FA) may be beneficial to broiler breeder (BB) development. Therefore, the effects of feeding sources of docosahexaenoic acid (DHA) and α-linolenic acid (ALA) from hatch through to 22 weeks of age (woa) on growth, organ weight, and jejunal histomorphology were investigated. A total of 588-day-old Ross × Ross 708 BB were reared on one of 3 diets: 1) control, corn-soybean meal diet, 2) Control + 1% microalgae (DMA, Aurantichytrium limacinum), as a source of DHA and 3) Control + 2.50% co-extruded full fat flaxseed and pulse mixture (FFF, 1:1 wt/wt), as a source of ALA. Diets DMA and FFF had similar total n-3 and n-6: n-3 ratio. Diets were allocated to floor pens (28 birds/pen) to give 9 or 6 replicates per diet for control or DMA and FFF, respectively and fed according to breeder curve in 3 phases: starter (0-4 woa), grower (5-19 woa), and pre-breeder (20-22 woa). Individual body weight (BW) was taken weekly and 6 birds/pen necropsied at 5 and 12 woa for gastrointestinal, spleen, bursa, and liver weight and samples for jejunal histomorphology. There was no (P > 0.05) diet effect on growth by 20 woa. With exception of 5 woa, pullets fed DMA showed (P < 0.001) lower BW coefficient of variation (C.V.) than pullets fed control between 2 and 7 woa. However, pullets fed DMA had higher BW CV at 20 woa than birds fed either control or FFF. At 5 woa, birds fed DMA had taller (P ≤ 0.01) villi and deeper crypt than birds fed either control or FFF but VH or CD were similar (P > 0.05) between CON and FFF pullets. At 12 woa, birds fed FFF had taller VH than birds fed control diet but similar (P > 0.05) to that of birds fed DMA. Therefore, different responses to sources of omega-3 FA may implicate other components, however, the BW uniformity and intestinal histomorphology responses suggested benefits of feeding omega-3 FA during rearing.

Feed Restriction Induced Changes in Behavior, Corticosterone, and Microbial Programming in Slow- and Fast-Growing Chicken Breeds

Simple Summary

Different genotypes of slow- and fast-growing chickens have phenotypic changes in appearance, behavior, and productivity in response to artificial selection. Feed restriction and gut microbiota play a vital role in controlling food intake, nutrition, and health. However, little is known about how feed restriction, as a benefit or chronic stress, influences behavior, stress response, and gut microbial programming in slow- and fast-growing chickens. This study aimed to explore slow- and fast-growing chickens who had feed restricted to 70% of ad libitum or were given ad libitum feed for 30 days to evaluate the effects on behavior, stress response, and gut microbiota. We found that feed restriction can influence behaviors in both slow- and fast-growing breeds. Feed restriction to 70% for 30 days can influence stress response and gut microbiota composition, but some changes are evident only in slow- or only in fast-growing chickens. The study provides a better understanding of how artificial selection has affected chicken biology and their response to stress challenge.

Abstract

This study aimed to explore the difference between two Chinese local broilers, one slow- and one fast-growing, in their response to a stress challenge. We conducted the study on slow- (Weining chicken) and fast-growing (Jinlinghua chicken) breeds, with 50 chickens from each breed either feed restricted to 70% for 30 days as a stress or given ad libitum to evaluate the effects on behavior, corticosterone, and microbial programming. Standing behavior was more frequent while exploration was less common in fast-growing breeds compared to slow-growing breeds. Food seeking and ingestion, exploration, and drinking increased, while resting decreased in the feed restricted treatments. There was no difference in corticosterone concentration between slow- and fast-growing chickens, but the level was affected by feeding treatments, and the interaction of breed and feed restriction. At the genus-level, the relative abundance of Bacteroides and Lactobacillus was higher, while Cloacibacillus and Megasphaera was lower in the slow-growing breed compared to the fast-growing breed. Feed restricted birds had a higher abundance of Mucispirillum, but lower abundance of Cloacibacillus, Clostridium XlVa and Clostridium IV. In conclusion, feed restriction to 70% for 30 days as a chronic stress stimulation caused more activity, elevated the stress response, and altered gut microbiota composition, but some changes were only evident in slow- or fast-growing chickens.

Effect of Qualitative Feed Restriction in Broiler Breeder Pullets on Stress and Clinical Welfare Indicators

The feed restriction applied during rearing of broiler breeders inflicts chronic hunger, and frustration due to unfulfilled behavioural needs for feeding. To alleviate the welfare problems associated with feed restriction, qualitative feed restriction allows a larger amount of feed to be provided without increasing the energy intake. In the present study, the aim was to investigate the effect of scatter-fed qualitative feed restriction on a range of welfare indicators in broiler breeders at the end of the rearing period. In total, 1,200 female breeder chicks of the genotype Ross 308 were housed in 24 pens: six pens of initially 50 birds per dietary treatment. The treatments were: (1) standard feed (Control), (2) standard feed diluted with oat hulls (Insoluble), (3) standard feed diluted with oat hulls and sugar beet pulp (Mixed), and (4) standard feed plus maize silage (Roughage). At 15 weeks of age, a blood sample was taken from 40 birds (10/treatment) five times within 24 h. The plasma was analysed for corticosterone concentration. At 19 weeks of age, a clinical welfare assessment was performed on all birds before they were sacrificed. From each bird, three feathers were plucked and macroscopically examined for the presence of fault bars. Feather length and weight were also recorded. Mortality was registered on occurrence throughout the rearing period. Treatment affected the plumage condition, footpad dermatitis, plumage dirtiness, vent pasting, and number of severe fault bars (P ≤ 0.05) but not plasma corticosterone concentration, hock burns, hyperkeratosis and mortality (P ≥ 0.17). There was an effect of the interactions between treatment and feather type on the total number of fault bars per feather, average position of the fault bars relative to the base of the feather, and growth rates of feather mass and length (P < 0.0001). Overall, the results showed improved welfare of Roughage birds and reduced welfare of Mixed birds, whereas the welfare of Insoluble birds did not seem to differ noticeably from that of Control birds. We recommend to further develop a feeding strategy that includes daily allocation of roughage to broiler breeders during the rearing period.

The effect of alternative feeding strategies on the feeding motivation of broiler breeder pullets

Due to genetic selection for fast growth and high breast meat yield, commercial strains of broiler chickens and broiler breeders are predisposed to high feed intake; however, feeding broiler breeders ad libitum impairs their health and reproductive performance. Broiler breeders are feed-restricted throughout rearing to maintain health and performance, yet feed restriction results in hunger, feeding frustration and lack of satiety. The objective of this study was to examine the effect of alternative feeding strategies, including feed additives (separately or combined) and a fixed non-daily feeding schedule, on the feeding motivation and welfare of broiler breeders during rearing. At 3 weeks of age, 180 Ross 308 breeder pullets were allocated to 90 cages and fed with one of five isocaloric treatments: (1) daily control diet (control), (2) daily calcium propionate diet (CaP), (3) daily soybean hull diet (SBH), (4) daily alternative diet (alternative: CaP + SBH) and (5) 4/3 control diet (four on-feed days and three non-consecutive off-feed days per week). The CaP diet included calcium propionate at 1.4% from 3 to 6 weeks of age, and at 3.2% from 7 to 12 weeks of age, and the SBH diet contained soybean hulls included at 40%. The alternative diet included both soybean hulls and calcium propionate at the same inclusion rate as the SBH and CaP diets, respectively. Pullets were weighed and scored for feather coverage every week. A feed intake test was conducted at 3, 4, 8, 10 and 11 weeks of age for 10 min during on- and off-feed days. At 12 weeks of age, feather samples were analysed for fault bars. Data were analysed using linear mixed regression models, with cage nested in the models and age as a repeated measure. At 4 weeks of age, pullets fed soybean hull-enriched diets (SBH and alternative diets) and those on the 4/3 schedule had lower feed intake than control pullets (P = 0.02). Feathers from pullets fed the SBH diet had fewer fault bars than those fed the CaP diet (P = 0.04). The results indicated that the inclusion of soybean hulls (alone or combined with calcium propionate) and a 4/3 feeding schedule can reduce feeding motivation of broiler breeders during early rearing.

Impact of an alternate feeding program on broiler breeder pullet behavior, performance, and plasma corticosterone

Broiler breeders are commonly feed restricted using some variation of skip-a-day feeding to prevent excessive body weight (BW) gain and poor flock uniformity that results in lower production levels. However, the level of feed restriction has increased leading to negative effects on broiler breeder welfare. Research needs to be conducted to evaluate alternative feeding programs to diminish the negative impact of restricted feeding on bird welfare. This research examined pullets that were fed soybean hulls (alternate day feeding, ATD) on the off day of a traditional skip-a-day feeding program in comparison to the standard skip-a-day program (SAD). The 2 dietary feeding treatments each had 3 replicate pens of 210 pullets each and were fed from wk 5 to 21 of age. Nitrogen-corrected true metabolizable energy and digestible amino acid coefficients of soybean hulls were determined. Body weight in the ATD feed program was significantly higher (P < 0.001) than the birds on the SAD feed program until 16 wk of age. Feed allocations for the SAD feeding program was increased at 11 wk of age to achieve similar BW prior to photo stimulation. The ATD feed program significantly improved BW uniformity of the birds for weeks 8, 12, 16, and 20. Hens fed on the SAD feed program had a lower mean egg production than the hens fed on the ATD program. There were significant differences on plasma corticosterone concentrations between the feeding days (24 or 48 h after feeding) in both feed programs. There was a shift in the behavior of the birds with significant differences in the feeding, foraging, and comfort behaviors between the feeding programs on the same feed day. Overall, feeding the ATD females soybean hulls on the off feed day improved the BW uniformity and egg production, but further research will be needed to determine potential differences in nutrient utilization or behavior of the pullets that positively impacted this flock performance.

The effect of alternative feeding strategies for broiler breeder pullets: 2. Welfare and performance during lay

Feeding broiler breeders to satiety has negative consequences on their health and reproduction. Alternative feeding strategies during rearing can improve welfare, although their implications during lay are not well understood. The objective was to examine the effect of rearing feeding treatments on the reproductive performance and feeding behavior of broiler breeders under simulated commercial conditions. At 3 wk of age, 1,680 Ross 308 pullets were allocated to 24 pens under 1 of 4 isocaloric treatments: 1) daily control diet; 2) daily alternative diet (40% soybean hulls and 1 to 5% calcium propionate); 3) 4/3 control diet (4 on-feed days, 3 non-consecutive off-feed days per week); and 4) graduated control diet. Feeding frequency of the graduated treatment varied with age and finished on a daily basis. At 23 wk of age, group sizes were adjusted to 40 hens, and 5 mature Yield Plus Males roosters were introduced to each pen. Pens were under the same daily feeding management and same diet during lay. The performance of broiler breeders (growth rate, body weight uniformity, and reproductive performance) was determined until 64 wk of age. At the end of lay, feeding motivation was examined with a feed intake test and a compensatory feeding test. Data were analyzed using linear mixed regression models, with pen nested in the models and age as a repeated measure. The laying rate of hens reared on the graduated treatment decreased slower compared to control hens, resulting in a higher cumulative egg production (178.2 ± 3.8 eggs/hen) than control hens (165.2 ± 3.8 eggs/hen, P < 0.01) by 64 wk of age. Hens reared on non-daily feeding treatments laid lighter eggs with relatively heavier yolks and had higher feed intake at the end of lay than hens fed daily during rearing (P = 0.02). In conclusion, rearing feeding treatments impacted the growth rate and body weight uniformity during lay, feeding motivation at the end of lay, and the laying rate and hatchability depending on hens' age.