Effect of environmental conditions during transport on chick weight loss and mortality

In ovo probiotic supplementation supports hatchability and improves hatchling quality in broilers

In modern broilers, the period of embryonic development constitutes a greater proportion of a broiler's productive life. Hence, optimum embryonic development can exert a significant influence not only on chick hatchability and hatchling quality but also on overall broiler growth and performance. Further healthy and active hatchlings are correlated with improved posthatch performance. In this regard, probiotics are good candidates to mediate early-life programming. Therefore, we evaluated the effect of In ovo probiotic spray application on broiler hatchability and hatchling quality. The experiment was set out as a completely randomized study with 2 independent trials. In each trial, 540 eggs (Ross 308) were either sprayed with phosphate buffered saline (PBS; control) or probiotics [∼9 log CFU/egg of Lactobacillus rhamnosus NRRL B-442(LR) or Lactobacillus paracasei DUP 13076 (LP)] during incubation. On day 18, eggs were transferred to the hatcher and set up for hatching. Starting on day 19, eggs were observed for hatching to determine the spread of hatch and hatchability. Hatched chicks were then assessed for quality using the Tona and Pasgar score and morphometric measurements including hatchling weight, yolk-free-body-mass and hatchling length were measured. Further, chicks were reared in floor pens for 3 wk to assess posthatch growth. Overall, In ovo probiotic supplementation improved hatchability and hatchling quality. Specifically, the spray application of LP improved hatchability by ∼ 5% without affecting the spread of hatch. Further, both LR and LP significantly improved Pasgar and Tona score, indicating an improvement in hatchling quality. Also, LP and LR significantly improved hatchling weight, yolk-free-body-mass, and posthatch growth in chicks. LR significantly improved hatchling weight and hatchling length (P < 0.05). Moreover, this increase in posthatch growth was positively correlated with hatchling weight in the probiotic groups. Overall, our study demonstrates that In ovo probiotic application exerts a positive effect on hatchability, hatchling quality, and subsequent posthatch growth.

Inhibition of mtDNA-PRRs pathway-mediated sterile inflammation by astragalus polysaccharide protects against transport stress-induced cardiac injury in chicks

Transport stress (TS) not only weakens poultry performance but also affects animal welfare. Additionally, TS can evoke cardiac damage by triggering sterile inflammation in chicks, but the underlying mechanism is not fully understood. Here, we aimed to elucidate how TS induces sterile inflammation and heart injury and to clarify the antagonism effect of astragalus polysaccharides (APS). We randomly divided 60 chicks (one-day-old female) into 5 groups (n = 12): Control_0h (Con_0h) group (chicks were slaughtered at initiation), Control group (stress-free control), TS group (simulated TS exposure for 8 h), TS plus water (TS+W) group, and TS plus APS (TS+APS) group. Before simulation transport, the chicks of TS+W and TS+APS groups were, respectively, dietary with 100 μL of water or APS (250 μg/mL). H&E staining was employed for cardiac histopathological observation. ELISA assay was used to measure oxidative stress marker levels (GSH, GPX, GST, and MDA). A commercial kit was used to isolate the mitochondrial portion, and qRT-PCR was employed to measure the mitochondrial DNA (mtDNA) levels. Furthermore, we evaluated the activity of mtDNA-mediated NF-κB, NLRP3 inflammasome, and cGAS-STING inflammatory pathways and the expression of downstream inflammatory factors by Western Blotting or qRT-PCR. Our findings revealed that APS notably relieved TS-induced myocardial histopathological lesions and infiltrations. Likewise, the decrease in proinflammatory factors (TNF-α, IL-1β, and IL-6) and IFN-β by APS further supported this result. Meanwhile, TS caused severe oxidative stress in the chick heart, as evidenced by decreased antioxidant enzymes and increased MDA. Importantly, APS prevented mtDNA stress and leakage by reducing oxidative stress. Interestingly, TS-induced mtDNA leakage caused a series of inflammation events via mtDNA-PRRs pathways, including TLR21-NF-κB, NLRP3 inflammasome, and cGAS-STING signaling. Encouragingly, all these adverse changes related to inflammation events induced by mtDNA-PRRs activation were all relieved by APS treatment. In summary, our findings provide the first evidence that inhibition of mtDNA-PRRs pathway-mediated sterile inflammation by APS could protect against TS-induced cardiac damage in chicks.

Effects and Interactions of Incubation Time and Preplacement Holding Time on Mortality at Placement, Yolk Sac Utilization, Early Feeding Behavior and Broiler Live Performance

The effects and interactions of incubation time and chick preplacement holding time on mortality at placement, utilization of yolk sac, crop filling rate, early feeding-drinking behavior, and broiler live performance were investigated. Ross 308 broiler hatching eggs from a 39-week-old flock were set in two identical setters in a commercial hatchery, with the setting time 12 h earlier in one machine. At the end of incubation, chicks were removed from the hatchers at the same time. Thus, the incubation times were either 504 h (normal incubation time (NIT) treatment) or 516 h (longer incubation time (LIT) treatment). After the pull time, chicks from each incubation time group were subjected to either 6, 24, 48, 60, or 72 h preplacement holding times. At placement, chicks were given access to feed and water. In total, 19,200 chicks were randomly assigned to a total of 10 subtreatment groups (2 incubation times × 5 preplacement holding times). Therefore, a total of 1920 chicks were used in each subtreatment group for the grow-out period in a commercial broiler house. For the first week of the experiment, 160 randomly selected as-hatched (not sexed) chicks were placed in 12 replicate floor pens (120 total pens). From the second week of age onward, chicks from two pens were combined into six replicate pens, with 320 chicks per replicate (60 total pens). An interaction was found between incubation time and preplacement holding time for residual yolk sac (RYS) weight (g, %) (p < 0.001). RYS weight was greater at pull time and at 6 and 24 h of preplacement holding in the NIT treatment compared to the LIT treatment, while differences were no longer evident at 48-72 h. The lowest percentage of chicks with full crops and eating activity was observed in the shortest preplacement holding time (6 h) group at 3 h after placement. As expected, the initial BW at placement clearly decreased with increasing duration after the pull time (p < 0.05), with the highest and lowest weights found in the 6 and 72 h holding time treatments, respectively. This BW difference was still evident at 35 d after placement and chicks held for the longest period after the pull time (72 h) showed the lowest BW (p < 0.001). However, there was no significant difference between the 6 and 60 h preplacement holding times. Mortality during the first 7 d after placement increased only when the preplacement holding time was extended to 72 h (p = 0.031). Similarly to the 7 d results, chicks held for 72 h exhibited higher 0-35 day mortality compared to those held for 6 or 24 h (p = 0.028). Neither BW nor mortality was affected by incubation time treatment at 35 d after placement (p > 0.05). It can be concluded that there were no significant differences in average BW and mortality, up to and including a 60 h holding time under thermal comfort conditions, but a 72 h preplacement holding time resulted in final BW and mortality being negatively affected. In addition, LIT tended to have a beneficial effect on BW and mortality compared to NIT when the preplacement holding time was shorter (6-24 h) but had a negative effect for extended holding times (48-72 h).

Effect of Environmental and Farm-Associated Factors on Live Performance Parameters of Broilers Raised under Commercial Tropical Conditions

Although temperature, relative humidity, and farm-associated factors are known to affect broiler live performance, data about the impact of these variables under commercial operations are still scarce. This study aimed to evaluate the effect of temperature, relative humidity, a thermal humidity index, management, and farm-associated factors on BW, BW gain, feed conversion ratio (FCR), and mortality of broilers raised to 35 d under commercial tropical conditions. The data analyzed included performance records of Ross 308 AP broiler flocks placed between 2018 and 2020. Environmental monitoring information was obtained from electronic sensors that captured data hourly from 80 flocks in 29 farms. Farm-associated factors were gathered using a survey of 86 farms. Three data analyses were conducted in parallel. Correlation analyses, one-way ANOVA, and machine learning techniques were employed. Results indicated that BW and BW gain were reduced, and FCR worsened (p < 0.001) up to 21 d when chickens were mainly exposed to temperatures 2.5 °C lower than the recommended optimums for each age period. At the same time, mortality at 28 and 35 d increased. In conclusion, all farm-associated factors affected chicken live performance. Variable importance analysis indicated that performance results at 14 and 21 d were significant to predict BW at 35. At the same time, sex, distance between the hatchery and farm, and farm altitude accounted for the most significant contributions from the farm-associated factors.

Prolonged fasting induces significant germ cell loss in chickens after hatching

Germ cell loss is a crucial biological event during germ cell development. The number of female germ cells determines the reproductive performance and egg production of hens. Various intrinsic and extrinsic factors affect germ cell loss, such as germ cell nest breakdown in early life and nutritional deficiencies during daily husbandry. Here, we examined the effect of fasting on the germ cell number of chicks. The results showed that 72 h fasting resulted in a higher germ cell loss than that by 24 h fasting in chicks. The RNA-seq analysis revealed that the genes of ribosome pathway were down-regulated and the biological processes of protein processing in endoplasmic reticulum were inhibited in starved chicks. Furthermore, in female chicks treated with 72 h fasting, the qPCR of ovaries showed down-regulation of ribosome-related genes, and transmission electron microscopy imaging of ovaries showed fewer ribosomes. The blood biochemical indices indicated that 72 h fasting reduced the liver functions and affected the glucose metabolism, lipid metabolites and ion metabolites. In summary, the present results concluded negative impacts on the germ cell pool by prolonged fasting in the early life of chicks and manifested that adequate management should be cared for fasted time for breeding.

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.

Welfare of domestic birds and rabbits transported in containers

This opinion, produced upon a request from the European Commission, focuses on transport of domestic birds and rabbits in containers (e.g. any crate, box, receptacle or other rigid structure used for the transport of animals, but not the means of transport itself). It describes and assesses current transport practices in the EU, based on data from literature, Member States and expert opinion. The species and categories of domestic birds assessed were mainly chickens for meat (broilers), end-of-lay hens and day-old chicks. They included to a lesser extent pullets, turkeys, ducks, geese, quails and game birds, due to limited scientific evidence. The opinion focuses on road transport to slaughterhouses or to production sites. For day-old chicks, air transport is also addressed. The relevant stages of transport considered are preparation, loading, journey, arrival and uncrating. Welfare consequences associated with current transport practices were identified for each stage. For loading and uncrating, the highly relevant welfare consequences identified are handling stress, injuries, restriction of movement and sensory overstimulation. For the journey and arrival, injuries, restriction of movement, sensory overstimulation, motion stress, heat stress, cold stress, prolonged hunger and prolonged thirst are identified as highly relevant. For each welfare consequence, animal-based measures (ABMs) and hazards were identified and assessed, and both preventive and corrective or mitigative measures proposed. Recommendations on quantitative criteria to prevent or mitigate welfare consequences are provided for microclimatic conditions, space allowances and journey times for all categories of animals, where scientific evidence and expert opinion support such outcomes.

Astragalus polysaccharide mitigates transport stress-induced hepatic metabolic stress via improving hepatic glucolipid metabolism in chicks

In the modern poultry industry, newly hatched chicks are unavoidably transported from the hatching to the rearing foster. Stress caused by multiple physical and psychological stressors during transportation is particularly harmful to the liver. Astragalus polysaccharide (APS) possesses multiple benefits against hepatic metabolic disorders. Given that transport stress could disturb hepatic glucolipid metabolism and the role of APS in metabolic regulation, we speculated that APS could antagonize transport stress-induced disorder of hepatic glucolipid metabolism. Firstly, newly hatched chicks were transported for 0, 2, 4, 8 h, respectively. Subsequently, to further investigated the effects of APS on transport stress-induced hepatic glucolipid metabolism disturbance, chicks were pretreated with water or APS and then subjected to transport treatment. Our study suggested that APS could relieve transport stress induced lipid deposition in liver. Meanwhile, transport stress also induced disturbances in glucose metabolism, reflected by augmented mRNA expression of key molecules in gluconeogenesis and glycogenolysis. Surprisingly, APS could simultaneously alleviate these alterations via PGC1α/SIRT1/AMPK pathway. Moreover, APS treatment regulated the level of PPARα and PPARγ, thereby alleviating transport stress-induced alterations of VLDL synthesis, cholesterol metabolism, lipid oxidation, synthesis and transport-related molecules. These findings indicated that APS could prevent the potential against transport stress-induced hepatic glucolipid metabolism disorders via PGC1α/ SIRT1/ AMPK/ PPARα/ PPARγ signaling system.