Breeder Pullets Research Articles

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

ABSTRACTBroiler breeders have impaired reproductive performance when fed to satiety but they can achieve an optimal hatching egg production under feed restriction. Feed restriction is a welfare concern due to signs of hunger, lack of satiety, and frustrated feeding motivation. The objective of this research was to examine the effect of a rationed alternative diet and non-daily feeding schedules on the performance and welfare of broiler breeder pullets reared under simulated commercial conditions. At 3 wk of age, 1,680 Ross 308 pullets were allocated to 24 pens fed with 1 of 4 treatments: 1) daily control diet (control); 2) daily alternative diet (40% soybean hulls and 1 to 5% calcium propionate); 3) 4/3 control diet (4 on-feed days per week; 3 non-consecutive off-feed days per week); and 4) graduated control diet (feeding frequency varied with age). Body weight and body weight uniformity were recorded at 3, 5, 7, 11, 17, and 21 wk of age. Pullets were scored for feather coverage, foot lesions, and hock burns biweekly. Physiological indicators (plasma glucose, corticosterone, hematology, and feather traits) and feeding motivation were also determined throughout rearing during on- and off-feed days. Data were analyzed using a linear mixed regression model, with pen nested in the model and age as a repeated measure. Compared to control, pullets under the 3 alternative feeding strategies had a lower feeding motivation during early rearing (P = 0.03), better feather coverage throughout rearing (P = 0.001), fewer feather fault bars (P = 0.006), and a delayed increase in the basophil to lymphocyte ratio (P = 0.001). These results indicate that the 3 alternative feeding strategies (the alternative, the graduated, and the 4/3 schedule) may decrease feeding motivation and alleviate stress compared to the control, suggesting an overall improvement in broiler breeder welfare without negative consequences on their performance.

Energy partitioning by broiler breeder pullets in skip-a-day and precision feeding systems

ABSTRACTAn empirical nonlinear mixed model was derived to describe metabolizable energy (ME) partitioning in Ross 308 broiler breeder pullets. Its coefficients described ME used for total heat production (HP) and growth. A total of 630 pullets were randomly and equally assigned to 2 treatments: precision feeding (PF) and conventional skip-a-day feeding (CON) from 10 to 23 wk of age. The PF system allowed birds to enter voluntarily at any time, weighed them, and provided access to feed for 60 s if their BW was less than the target BW. Birds in the CON treatment were fed as a group on alternate days. Energetic efficiency of pullets was evaluated using residual total heat production (RHP), defined as the difference between observed and predicted total HP. Additionally, ME intake (MEI), ADG, HP, and cumulative feed conversion ratio (FCR) were calculated for the entire experimental period. The energy partitioning model (P < 0.05) predicted MEI = (120+u)BW0.68 + 1.52(ADG) + ε. Total HP was (120 kcal/kg0.68 + u); the energy requirement for each g of BW gain was 1.52 kcal/d. The random variable u ∼ N (0, σu2) indicated a pen level HP standard deviation σu = 12.1 kcal/kg0.68. Over the experimental period, for CON and PF treatments, respectively, MEI was 194 and 174 kcal/d (P < 0.001); ADG was 15.3 and 15.4 g/d (P = 0.94); HP was 129 and 111 kcal/kg0.68 (P < 0.001); FCR was 4.888 and 4.057 (P < 0.001); and RHP was 0.12 and –0.12 kcal/kg0.68 (P = 0.73). The CON pullets had similar ADG, but higher MEI relative to PF, consistent with levels of heat production predicted by RHP. The PF pullets had lower cumulative FCR compared to CON pullets. The PF pullets lost less energy as heat, likely because they were fed continuously, reducing the need to store and mobilize nutrients compared to CON pullets. Thus, increased feeding frequency likely increased PF pullet efficiency.

Molecular characterization of a novel picobirnavirus in a chicken.

Picobirnaviruses (PBVs) are bisegmented viruses with a wide geographical and host species distribution. The number of novel PBV sequences has been increasing with the help of the viral metagenomics. A novel picobirnavirus strain, pbv/CHK/M3841/HUN/2011, was identified by viral metagenomics; the complete segment 1 (MH327933) and 2 (MH327934) sequences were obtained by RT-PCR from a cloacal sample of a diseased broiler breeder pullet in Hungary. Although the conserved nucleotide (e.g., ribosome binding site) and amino acid motifs (e.g., ExxRxNxxxE, S-domain of the viral capsid and motifs in the RNA-dependent RNA polymerase) were identifiable in the chicken picobirnavirus genome, the putative segment 1 showed low (<30%) amino acid sequence identity to the corresponding proteins of marmot and dromedary PBVs, while segment 2 showed higher (<70%) amino acid sequence identity to a wolf PBV protein sequence. This is the first full-genome picobirnavirus sequence from a broiler breeder chicken, but the pathogenicity of this virus is still questionable.

Impact of Skip-a-Day and Every-Day Feeding Programs for Broiler Breeder Pullets on the Recovery of Salmonella and Campylobacter following challenge.

The impact of restrictive feeding programs on Salmonella and Campylobacter colonization and persistence after challenge was investigated for broiler breeder pullets housed in an experimental rearing facility. Pullet-chicks were placed on litter in 3 feeding program rooms and each room contained 2 replicate pens. The feeding programs were: (1) Skip-a-day in trough feeders (SAD); (2) Every-day in trough feeders (EDT); (3) Every-day on the pen litter (EDL). On d 1, an additional group of hatchmate chicks were housed in a separate room and gavaged with Salmonella Typhimurium, to later serve as seeder chicks. After seeders were confirmed Salmonella-positive at wk 4, at wk 5 seeders were placed into each feeding program pen to commingle with 135 penmates. At 7, 9, 11, 17, 18, and 20 wk the litter surface in each pen was sampled using intermittently stepped-on drag-swabs. At 8, 12, 16, and 20 wk of age the ceca were sampled from 10 penmates/pen and 2 pooled spleen samples/pen were collected. SAD litter remained Salmonella-positive through 20 wk of age while EDL and EDT pens had no detectible litter Salmonella recovery by 18 and 20 wk. EDL fed pens had no direct (<102 cfu/mL) litter Salmonella recovery during the entirety of the experiment. Salmonella prevalence for ceca from SAD pullets was significantly (P < 0.05) higher at 8 wk (70%) compared to EDT (40%) and EDL (30%). At wk 12, SAD pullets for both on and off-feed sampling days had significantly higher Salmonella recovery (40%), compared to EDT and EDL (both at 5% recovery). By 16 and 20 wk, only the SAD pullets on the on-feed day (48h without feed) had recovery of Salmonella at 20%. Salmonella recovery in pooled spleen samples did not appear associated with feeding treatments (22% positive). The remaining pullets challenged with Campylobacter at 21 wk produced similar trends as was seen for Salmonella. SAD program pullets had significantly higher Campylobacter from ceca (80 to 100%) compared to pullets on EDL (30 to 60%) or EDT (40 to 95%). These results suggest that using a Skip-a-Day feeding program for broiler breeder pullets contributes to persistently higher Salmonella and Campylobacter ceca colonization and litter prevalence.

Study of dynamic of chicken infectious anaemia virus infection: which sample is more reliable for viral detection?

ABSTRACTChicken infectious anaemia virus (CIAV) is a widely distributed immunosuppressive agent. SPF flocks and eggs used for vaccine production and diagnostics must be CIAV-free. Detection of CIAV infection in SPF flocks involves primarily serology or other invasive methods. In order to evaluate different types of samples for rapid detection of CIAV infection, a trial was conducted in serologically negative broiler breeder pullets vaccinated with a commercial live-attenuated CIAV vaccine. Controls and vaccinated groups were sampled before and after vaccination. Invasive and non-invasive samples were used for CIAV DNA detection by real-time PCR. Seroconversion occurred at 14 days post-inoculation (DPI) in the vaccinated group, whereas CIAV genome was detected by qPCR at 7 DPI in both invasive and non-invasive samples. Only invasive samples remained qPCR positive for CIAV DNA by 21 DPI despite seroconversion of the chickens.

The Quest for Welfare-Friendly Feeding of Broiler Breeders: Effects of Daily vs. 5:2 Feed Restriction Schedules

Restricted feeding of broiler breeders is required for improved long-term health and welfare. Because feeding frustration and hunger are major welfare concerns during rearing, many suggestions have been made to decrease the negative feelings of hunger while maintaining suitable growth rates and reproductive health. Non-daily (“skip-a-day”) feeding schedules are commonly used around the world to increase portion sizes at meal times while restricting intake but these practices are prohibited in many countries due to welfare concerns on fasting days. We compared birds raised on a non-daily feeding schedule (2 non-consecutive fasting days per week, 5:2), previously suggested as a welfare-friendlier non-daily alternative, to birds raised on daily feed restriction. We found signs of increased physiological stress levels in 5:2 birds, including elevated heterophil to lymphocyte ratios (1.00 for 5:2 vs. 0.75 for daily fed at 12 weeks of age), increased adiposity (0.21% lean body weight [LBW] for 5:2 vs. 0.13% LBW for daily fed), and reduced muscle growth (pectoral muscle 5.94% LBW for 5:2 vs. 6.52% LBW for daily fed). At the same time, 5:2 birds showed signs of lower anxiety before feeding times (activity was reduced from 10.30 in daily fed to 4.85) which may be a result of the lower feed competition associated with larger portion sizes. Although we found no difference in latency to first head movement in tonic immobility between the treatments (136.5 s on average for both groups), 5:2 birds generally showed more interest in a novel object in the home pen which indicated increased risk taking and reduced fear while fasting. The 5:2 birds in this study showed no signs of learning the feeding schedule, and this unpredictability may also increase stress. Taken together, the effects of 5:2 vs. daily feed restriction on the welfare of broiler breeder pullets remain inconclusive and differ between feeding and fasting days. In addition to reducing stress by minimizing the number of fasting days, we suggest that a shift to more predictable schedules may help improve the welfare of broiler breeder pullets.

Evaluation of Antibiotics to Control Mycoplasma gallisepticum in Broiler Breeder Chickens

This study aims at the evaluation of the efficacy of Pulmotil and Denagard in comparison to the generic tylosin against Mycoplasma gallisepticum (MG) infection in broiler breeders. A total of 600 twenty four-week old broiler breeder pullets along with their 60 roosters of the Ross 308 strain, were equally subdivided into four treatments of 150 birds each with 3 replicates per treatment (50 pullets and 5 roosters/pen). The MG-free birds of Group 1, the Control, were kept in a separate house and left with no MG-challenge or drug administration while those of groups 2, 3, and 4 were raised in another house and previously challenged with MG at 2 and 24 weeks of age respectively. Every 4 weeks and for 3 consecutive days, birds of group 3 were administered Pulmotil (3–21 Weeks) and Denagard (25–44 weeks), whereas those of Group 4 were treated throughout the trial with generic Tylosin. Production performance parameters were not significantly different among the differently treated birds. At 30 weeks of age, Pulmotil-Denagard treatment significantly reduced the tracheal MG counts to a similar level to that of the controls and restored the fertility of the MG challenged birds at 39 weeks of age. At 35 weeks of age, Pulmotil-Denagard treatment significantly reduced the frequency of day-old progeny with positive airsac lesions. It also reduced MG colonization in the airsacs of the day-old offsprings of the 35 and 39 week old breeders. As the Pulmotil-Denagard treatment significantly reduced the MG colonization of bird tissues, it reduced MG sera titers at 12, 20 and 30 weeks of age, and increased titers against IB, IBD and ND at later stages. In conclusion, the use of Pulmotil/Denagard program is highly recommended in MG-infected breeder farms, and protects against any potential MG endemic infection.

Growth curve and diet density affect eating motivation, behavior, and body composition of broiler breeders during rearing

The aim of this work has been to assess the effect of diet density [control (CON) or 15% diluted (DIL)] and growth curve [recommended by the genetic line (RBW) or 15% heavier (HBW)] and their interaction on BW uniformity, feeding motivation, behavior, and body composition of broiler breeder pullets. A total of 3,000 one-day-old female breeders Ross 308, distributed in 20 pens, was randomly assigned to each treatment. Feed allowance was weekly adjusted to reach the desired BW. Feed was provided as pelleted (zero to 3 wk) and crumble (4 to 19 wk). Time eating was measured at 7, 11, and 19 weeks. A feeding rate test was performed after 11 weeks. Behavior was observed at 9 and 15 wk, by visual scan. At 6, 13, and 19 wk of age, one bird/pen was slaughtered for weighing different organs and analyzing the composition of empty whole bodies. Treatments did not affect BW uniformity; relative weights of the ovary, oviduct, or gizzard; or protein content of empty BW. Time eating varied with the growth curve at 19 wk (P < 0.05), HBW pullets spent 19 more min eating than RBW pullets. DIL led to 4 and 8 more min eating at 19 wk for pullets of RBW and HBW (P < 0.05), respectively. Pullets fed DIL consumed 30% (P < 0.05) less during the feeding rate test when kept on a restricted regimen, and they had lower compensatory energy intake after ad libitum feeding than those fed CON, indicating lower feeding motivation. Behavior was affected by the age and by the time of the d measured, but it did not change with the treatments. Birds spent most time pecking objects (50%), feeding (28%), and drinking (17%). Pullets fed DIL had 8% lower breast yield at different ages and higher empty digestive tracts at 6 weeks. Body composition varied with age; fat content increased from 12.7 to 15.9 to 19.8% for 6, 13, and 19 wk, respectively. The lowest body fat was observed for RBW pullets fed DIL (P = 0.003) at 19 weeks. Feeding DIL diets to HBW pullets could be done to increase the time spent eating and reduce their feeling of hunger without negative effects on body composition. However, its influence on behavior and BW uniformity was not proved.

Precision feeding: Innovative management of broiler breeder feed intake and flock uniformity

Achieving high lifetime productivity with broiler breeder flocks is challenging because feed restriction intensity continues to increase due to selection for efficient, fast growing, and high yielding broilers. Flock uniformity is compromised by intense competition for limited feed. Equitable feed allocation and stable metabolic rates are likely to increase reproductive efficiency. A prototype precision feeding (PF) station was developed to sequentially feed birds according to their individual needs. If pullets were under target BW, the station provided small amounts of feed during short feeding bouts. The objectives of the current study were to determine whether a sequential PF system could control BW of individual group-housed pullets by matching real-time BW to BW targets, and to quantify fluctuations in metabolic rate using continuous or stepwise increases in target BW. Two treatments were used in a completely randomized design: CON, the Ross 708 target BW curve interpolated hourly; and STEP, the Ross 708 BW curve updated every 21 days. Twenty Ross 708 broiler breeder pullets were assigned to the treatments (n = 10 per treatment). All pullets were fed by one PF station in a single pen from 35 to 140 d of age. Feed intake and BW records were used to evaluate BW and BW variation to estimate maintenance ME requirements, and to evaluate feeding patterns. Differences were reported as significant where P < 0.05. Precision feeding allowed different feeding programs to be evaluated in the same pen. In both treatments, BW CV decreased to less than 2% by wk 20. Complex temporal differences in feed intake and BW reflected treatment-specific target growth trajectories. Metabolic rate in the STEP treatment increased 70 to 100% during wk in which rapid growth was permitted, compared with wk in which BW targets were held constant. Precision feeding shows promise both as a data acquisition system for poultry researchers and breeders, and as a means of increasing broiler breeder flock uniformity.

Fowl Adenoviruses D and E Cause Inclusion Body Hepatitis Outbreaks in Broiler and Broiler Breeder Pullet Flocks.

Twenty-four fowl adenoviruses (FAdVs) were isolated from broiler and broiler breeder pullet flocks in Iran during 2013-2016 and were identified and characterized. All FAdVs were from inclusion body hepatitis (IBH) cases, showing an enlarged and pale yellow liver with multiple petechial hemorrhages. Phylogenetic analyses of partial hexon gene sequences are an adequate and quick method for differentiation and genotyping. The isolates were subjected to PCR to amplify a 590-bp fragment from the hexon gene. Sequence analysis revealed the presence of two species D and E. Eighty FAdV isolates were genetically related to the strain EU979378 of FAdV-11 (96.5% to 97.6% identity), and six isolates were related to the strain EU979375 of FAdV-8b (97% identity). The results indicated that two FAdV serotypes (11 and 8b) are high prevalence serotypes of FAdVs in Iran and are pathogenic enough to cause IBH in young chicks. Therefore, preventive measures against FAdV infection on poultry farms should be implemented.

Growth heterogeneity in broiler breeder pullets is settled before the onset of feed restriction but is not predicted by size at hatch

Growth heterogeneity in broiler breeder pullets is settled before the onset of feed restriction but is not predicted by size at hatch

Feeding, foraging, and feather pecking behaviours in precision-fed and skip-a-day-fed broiler breeder pullets

Broiler breeder chickens are feed-restricted to control growth and maximize chick production. Feed restriction creates welfare concerns as conventional skip-a-day feeding can increase activity levels and oral stereotypies during the rearing period. A precision feeding system has been developed to provide small meals to individual birds multiple times throughout a day when their BW is less than a target BW.Objectives of the current study were to investigate whether precision feeding affected: 1) restlessness in broiler breeder pullets, by comparing the prevalence of standing and walking to a flock fed every other day and 2) foraging frustration, by comparing foraging and stereotypic oral behaviours in precision-fed and skip-a-day-fed broiler breeders. Using a randomized complete block design, precision feeding and skip-a-day pens were each represented in 6 blocks (N=6) with 45 Ross 308 pullets per pen. Skip-a-day-fed pullets were fed at 10:30 am on alternating mornings. Live behaviour observations of pullets (15min per pen, 12 focal pullets) were conducted during morning (08:00–09:55) and afternoon (13:45–15:40) sessions once per week, from 10 to 21 weeks of age. Behaviours observed during instantaneous 1min scan sampling included: stand/walk, forage, sit, feather peck, dust-bathe, peck at wing-tag, pecking of the drinker, feeder, or pen wall, and ‘other’ behaviours. Means were reported as different when P<0.05. Feeder and pen wall pecking did not differ between treatments. Skip-a-day-fed pullets performed more stand/walk (6.15±0.05 vs. 5.69±0.05; F1,10=43.97; P<0.0001), forage (3.29±0.05 vs. 3.04±0.04; F1,10=15.37; P=0.0029), and feather peck (0.16±0.01 vs. 0.03±0.01; F1,10=58.31; P<0.0001) behaviours compared with precision-fed pullets, respectively. Precision-fed pullets performed more sitting (0.23±0.01 vs. 0.15±0.01; F1,10=20.15; P=0.0012) and drinker pecking (2.60±0.01 vs. 0.15±0.01; F1,10=39.11; P<0.0001) behaviours compared with skip-a-day-fed pullets, respectively. Feather pecking and foraging were not consistently inversely related, suggesting feather pecking in broiler breeders may have additional causal factors beyond re-directed foraging. An increase in drinker pecking suggests feeding motivation is still present in precision-fed flocks. In conclusion, compared with skip-a-day feeding, precision feeding appears to decrease, but not eliminate, feeding motivation in feed-restricted broiler breeder pullets.

Aggression and social rank fluctuations in precision-fed and skip-a-day-fed broiler breeder pullets

In broiler breeders, conventional skip-a-day feeding leads to hunger-related aggression. As an alternative, a precision feeding system was developed to provide small meals to individual birds multiple times each day, sheltered from competition. Two objectives investigated whether: 1) aggression among pullets; and 2) the number of social rank fluctuations differed between precision and skip-a-day feeding systems. Using a randomized complete block design, a precision-fed and skip-a-day-fed pen of broiler breeders was represented in each of 6 blocks (Total=540 pullets; 45 Ross 308 pullets per pen; 12 pens with N=6 pens per treatment). Pen was the experimental unit. Aggressive encounters (eg. aggressive pecking, fighting, and threat behaviours) were recorded via continuous observations weekly from 10 to 21 weeks of age. Birds not involved in aggressive encounters or threats were categorized as ‘non-participants’. Using an Aggression Rank Index, the rank of each pullet was determined by the number of aggressive encounters and threats won divided by the total number of aggressive encounters and threats. Rank fluctuations were used to measure the impact of feeding system on overall group stability within a pen. Treatment differences were analyzed using a generalized linear mixed model. Precision-fed pullets were more aggressive compared with skip-a-day-fed pullets (12.73±0.61 vs. 8.02±0.48, respectively; F1,10=36.35; P=0.0001). However, no difference was found in the number of rank fluctuations. Overall, the increased aggression exhibited in precision-fed pullets did not appear to cause social rank stability concerns.

Growth heterogeneity in broiler breeder pullets is settled before the onset of feed restriction but is not predicted by size at hatch.

Uniform growth is a desirable trait in all large-scale animal production systems because it simplifies animal management and increases profitability. In parental broiler flocks, so-called broiler breeders, low growth uniformity is largely attributed to the feed competition that arises from quantitatively restricted feeding. As feed restriction is crucial to maintaining healthy and fertile breeders, several practices for reducing feed competition and the associated growth heterogeneity have been suggested and range from nutrient dilution by increasing fiber content in feed to intermittent fasting with increased portion size ("skip a day"), but no practice appears to be entirely effective. The fact that a large part of the heterogeneity remains even when feed competition is minimized suggests that some growth variation is caused by other factors. We investigated whether this variation arises during embryonic development (as measured by size at hatch) or during posthatch development by following the growth and body composition of birds of varying hatch sizes. Our results support the posthatch alternative, with animals that later grow to be small or large (here defined as >1 SD lighter or heavier than mean BW of the flock) being significantly different in size as early as 1 d after gaining access to feed ( < 0.05). We then investigated 2 possible causes for different postnatal growth: that high growth performance is linked 1) to interindividual variations in metabolism (as measured by cloacal temperature and verified by respirometry) or 2) to higher levels of social motivation (as measured in a social reinstatement T-maze), which should reduce the stress of being reared in large-scale commercial flocks. Neither of these follow-up hypotheses could account for the observed heterogeneity in growth. We suggest that the basis of growth heterogeneity in broiler breeder pullets may already be determined at the time of hatch in the form of qualitatively different maternal investments or immediately thereafter as an indirect result of differences in incubation conditions, hatching time, and resulting fasting time. Although this potential difference in maternal investment is not seen in body mass, tarsometatarsal length, or full body length of day-old chicks arriving at the farm, it may influence the development of differential feed and water intake during the first day of feeding, which in turn has direct effects on growth heterogeneity.

Lysine, methionine, phenylalanine, arginine, valine, isoleucine, leucine, and threonine maintenance requirements of broiler breeders

Five hundred and sixty Cobb-Vantress broiler breeders were used to determine the maintenance requirement of dietary Arg, His, Ile, Leu, Lys, Met, Phe, Thr, and Val in 10 21-d assays using the comparative slaughter technique. Fifty sexually immature broiler breeder pullets per assay were given crystalline amino acid diets containing graded levels of Arg, His, Ile, Leu, Lys, Met, Phe, Thr, or Val, respectively, representing 0, 10, 20, 30, 40% of their suggested requirement level (NRC, 1994) with all other amino acids maintained at 40% of their suggested requirement level. Sixty hens were slaughtered prior to the beginning of the study to assess initial body composition at 3 weight groups. Linear regression lines (protein accretion vs. amino acid intake) were determined and the maintenance requirements were calculated based on zero protein accretion. The maintenance requirements expressed on a metabolic weight basis were determined to be 174, 94, 52, 81, 60, 126, 133, and 155 mg/kg0.75/d for Arg, Ile, Leu, Lys, Met, Phe, Thr, and Val, respectively. Additionally, the maintenance requirements, expressed on metabolic protein weight basis, were determined to be 651, 329, 172, 295, 223, 523, 478, and 546 mg/kgCP/d for Arg, Ile, Leu, Lys, Met, Phe, Thr, and Val, respectively. The requirement for His could not be established as the results obtained were outside of assay range.

Effects of broiler breeder management on pullet body weight and carcass uniformity

An experiment was conducted to study the effect of broiler breeder feeding management practices on pullet performance, BW uniformity, and carcass traits during rearing (to 22 wk of age). At 3 wk of age, 1,200 Ross 308 breeder pullets were assigned to one of 5 treatments: 1) control: standard mash diet, fed daily; 2) high fiber: mash diet containing 25% lower nutrient density, fed daily; 3) scatter: standard diet in pellet form scattered on litter, fed daily; 4) skip-a-day: standard mash diet, fed on alternate days; or 5) grading: standard mash diet, fed daily (birds sorted into low, average, and high BW groups every 4 wk). Birds on the high fiber treatment consumed more feed (P < 0.0001) and had the highest feed conversion ratio (FCR; P < 0.004) but the lowest ME to gain and CP to gain ratios (P ≤ 0.002). Skip-a-day treatment pullets consumed more ME and CP than birds in any other treatment (P < 0.001). Grading yielded the highest BW uniformity at 22 wk of age (CV = 6.2%), while control and high fiber treatment groups were least uniform (CV > 15%; P < 0.0001). Skip-a-day feed restriction produced birds with the significantly lowest breast muscle and highest liver weight compared to all other treatments (P < 0.05). Variation in shank length, chest width, and breast muscle was lowest in the grading treatment, whereas the CV for fat pad and liver was lowest in the skip-a-day treatment. In this trial, broiler breeder target BW profiles were achieved using combinations of quantitative and qualitative feed restriction, or preemptive management practices. Qualitative diet dilution and skip-a-day management did little to increase flock uniformity relative to the control during the most intense period of feed restriction (7 to 19 wk). Scatter feeding increased flock uniformity to a small degree, whereas grading yielded the highest increase in BW and carcass trait uniformity.

Effects of different dietary protein levels during rearing and different dietary energy levels during lay on behaviour and feather cover in broiler breeder females

An experiment was conducted to determine the effects of different dietary protein levels during rearing and different dietary energy levels during lay on behaviour and feather cover in broiler breeder females. A 2×3×2 factorial arrangement of treatments was used. A total of 2880 Ross 308 14-day-old broiler breeder pullets were fed between weeks 2 and 22, a high (CPh) or low (CPl) crude protein (CP) diet. Between weeks 22 and 45, the breeders were fed either a high, standard, or low energy diet (3000, MEh1; 2800, MEs1; 2600, MEl1, kcal/kg AMEn (apparent metabolisable energy, corrected for nitrogen), respectively). Between weeks 45 and 60, the breeders were fed a standard or high energy diet (2800, MEs2; 3000, MEh2, kcal/kg AMEn, respectively). During rearing, CPl pullets received 12.1% more feed, resulting in a 137% increased eating time and 47% decreased eating rate. This increased feeding, sitting, and comfort behaviour while standing, walking, foraging, stereotypic object pecking, and bird pecking were reduced. Feather cover was poorer when pullets were fed a low protein diet during rearing, but this effect was not present during lay. A 7.6% lower feed intake for the MEh1 birds resulted in a 21% decreased eating time and 19% increased eating rate compared with the MEs1 birds. Birds on the MEh1 diet spent less time feeding and more time sitting, comfort, and stereotypic object pecking behaviour compared with the MEs1 birds. Birds fed the MEh1 diet showed a poorer feather cover during the entire lay compared with the MEs1 birds. A 7.7% higher feed intake for the MEl1 birds resulted in a 31% increased eating time and 18% decreased eating rate compared with the MEs1 birds. MEl1 birds spent more time feeding and less time foraging, comfort, and stereotypic object pecking compared with the MEs1 birds. No effect on feather cover was found for the MEl1 compared with the MEs1 birds. The MEh2 birds received 8.8% less feed resulted in a 16% decreased eating time and 9% increased eating rate. The lower feed intake resulted in less time spent feeding and standing, and more time spent foraging and comfort behaviours. Feather cover was not affected by dietary energy level during the second phase of lay. In conclusion, feeding broiler breeders a higher amount of feed due to a higher energy-to-protein ratio resulted in an increased eating time and less stereotypic object pecking behaviour what is an indication of reduced hunger and frustration. This was much more expressed during rearing than lay. However, a low daily protein intake during rearing and first phase of lay can lead to a poorer feather cover.

Effect of dietary phytoestrogens, feed restriction, and their interaction on reproductive status of broiler pullets

Background and Aim: A major problem faced by the broiler industry around the world is a lowered reproductive fitness of breeding hens which can cause major economic impact in terms of lowered hatchable egg production. In broiler breeders, a lot of the selection pressure has been exerted on growth, conformation and feed efficiency as a result broiler breeder hens are prone to several metabolic disorders and reproductive anomalies. Present study was conducted to assess the effect of phytoestrogen, feed restrictions (75% of their control ad libitum), and their interaction on reproductive parameters in high and low body weight broiler breeder hens. Materials and Methods: One hundred twenty-eight healthy female broiler breeder pullets were divided randomly into eight groups from the same hatch and strain. They were transferred to individual laying cages. Birds received ad libitum drinking water and feeding, depend on divided group i.e., ad libitum or restricted feeding (75% of control ad libitum) counterpart separately for heavy or low body weight till first egg laid in respective groups. Experimental diets made with practical feed ingredients as per institution recommendation (broiler breeder ration) as per experimental planning. Results: Phytoestrogen significantly (p<0.05) improved egg number and size in broiler breeding hens by checking reproductive anomalies (internal laying, double hierarchy, and follicular atresia), restructuring ovarian, and oviductal functional development besides improved physiological maturation of infundibulum. Unlike phytoestrogen, feed restriction as expected delayed the age of sexual maturity but helped in a reduction of ovary weight, number of yellow follicle, number of atretic yellow follicle, incidence of double hierarchy, and internal ovulation. Interaction between phytoestrogen and feed restriction did not give any additional remunerative advantage. Conclusions: It is concluded that phytoestrogens and limited feed restriction likely to improve reproductive efficiency around age of sexual maturity by overcoming the reproductive anomalies and modulating the ovarian and oviduct maturation favorably in broiler breeder hen.

Effect of age at photostimulation on sexual maturation in broiler breeder pullets

Genetic selection programs in broiler stocks have contributed to changes in the responsiveness of the broiler breeder female to nutritional factors. A study was conducted to investigate the effect of photostimulation (PS) age on sexual maturity traits in current broiler breeder pullets. Seven hundred twenty Ross 308 pullets with full access to feed to 1 or 3 wk of age were divided among 8 environmental rooms to 16 wk of age. At this time, 128 pullets (64 per initial feeding treatment) were randomly assigned to individual cages in 8 rooms with 16 pullets per room. Pullets were PS at 17 (PS17), 19 (PS19), 21 (PS21), or 23 (PS23) wk of age by increasing the day length from 8L:16D to 16L:8D (multiple steps). Each hen was dissected on the morning after first oviposition (sexual maturity). Data were analyzed by 2-way ANOVA with additional analysis of covariance analysis done using sexual maturity on BW as a covariate. Sexual maturation occurred later with later PS ages. Rate of sexual maturation was accelerated at later PS ages, although age at PS did not affect variation in age at sexual maturity. Despite a 42 d difference in PS age between the PS17 and PS23 groups, only a 25 d difference existed in mean age at sexual maturity among these groups. Initial egg weight, breast muscle weight, frame size, and abdominal fat pad weight at sexual maturity increased in birds with later PS ages. Covariate analysis indicated that these effects were influenced primarily by increased age and BW at sexual maturity in later PS birds. Pullets PS at 17 wk of age had 11.0 large white ovarian follicles, compared with 14.9 in PS23 birds. Comparison to previous studies demonstrates that the years of genetic selection for growth traits have not changed the interval between PS and sexual maturation. Previous research published on this theme likely had a confounding effect of mean BW on estimates of variation at various PS ages. Photostimulating later presented advantages with regard to development of the reproductive tract; these effects were BW dependent.

Molecular detection and isolation of avian metapneumovirus in Mexico

We conducted a longitudinal study to detect and isolate avian metapneumovirus (aMPV) in two highly productive poultry areas in Mexico. A total of 968 breeder hens and pullets from 2 to 73 weeks of age were analysed. Serology was performed to detect aMPV antibodies and 105 samples of tracheal tissue were collected, pooled by age, and used for attempted virus isolation and aMPV nested reverse transcriptase-polymerase chain reaction (nRT-PCR). The serological analysis indicated that 100% of the sampled chickens showed aMPV antibodies by 12 weeks of age. Five pools of pullet samples collected at 3 to 8 weeks of age were positive by nRT-PCR and the sequences obtained indicated 98 to 99% similarity with the reported sequences for aMPV subtype A. Virus isolation of nRT-PCR-positive samples was successfully attempted using chicken embryo lung and trachea mixed cultures with subsequent adaptation to Vero cells. This is the first report of detection and isolation of aMPV in Mexico.