Early Chicks Research Articles

Effect of feeding chitosan and blend of essential organic acids on growth performance, haematological parameters and innate immunity in early aged male layer chicks.

The use of antibiotics as conventional feed additives in poultry operations have proven useful, however resulted serious health concerns to consumer due to their bio-accumulation, besides rising problem of antimicrobial resistance in microbes, thus, an alternative to antibiotic growth promoter have called for. One of the aim of the experiment was to assess the lone and combined effects of feeding of chitosan oligosaccharide (COS) and blend of organic acids and short chain fatty acids in essential oils on growth performance, haematological parameters, relative lymphoid organ weight and innate immunity in early aged layer chick(male birds). A total of ninety, day-old chicks were randomly allotted into five groups: CO, Control group fed only poultry feed ; AGP, antibiotic growth promoter fed Avilomycin at the dose of 200mg/kg of poultry feed; CH, chitosan oligosaccharide fed at the rate of 100mg/kg feed; OE, blend of organic acids and short chain fatty acids in essential oils contained 1000 to 2000mg/kg feed in a graded dose per week and CH + OE, chitosan oligosaccharide plus blend of organic acids and short chain fatty acids in essential oils at consistent rate and manner as followed for each of given feed additives when fed individually. Data on growth performance, samples for haematological parameters and innate immunity were measured and assayed on 7th, 21st and 42nd day post feeding (dpf) respectively. The results showed that compared with the control group; there is a marginal gain in body weight at 7th and 21st dpf in CH group and the corresponding CH + OE group. Feed conversion ratio in CH group was remarkably good at 7th and 21st dpf. No significant difference was observed in relative organ weights of thymus, spleen and Bursa of Fabricius in treatment groups as compared to control birds; however a significant rise in splenic weight index in OE fed birds at 42nd dpf noted. Haematological changes were inconsequential in treatment groups with an exception to enhancement of heterophil to lymphocyte ratio (H:L ratio) in CH group at 42nd dpf. Serum lysozyme activity proportionately elevated in CH + OE group on 21st and 42nd dpf when measured against control group; on the other hand no detectable augmentation of gut lysozyme activity observed. Both serum bactericidal and gut bactericidal activity boosted in combinatorial group at 42nd dpf. These results indicated that early age feeding of chitosan individually or combination with organic acids and short chain fatty acids in layer chick is beneficial, as it has the potential to enhance body weight gain to some extent and improves systemic and localized innate immunity to offer protection against infectious assaults thus may avoid early chick mortality in farms.

Natural recolonisation of sub-Antarctic Marion Island by Common Diving Petrels Pelecanoides urinatrix

Nocturnal burrow-nesting seabirds are notoriously difficult to study and can go unnoticed for years in remote areas. One of these species is the Common Diving Petrel Pelecanoides urinatrix, which has a circumpolar breeding distribution in the Southern Ocean, including at the sub-Antarctic Prince Edward Islands. At Marion Island, the larger of the two islands, the species was extirpated by cats that were introduced in 1948. The cats were eradicated by 1991, and Common Diving Petrels were discovered in burrows in coastal Poa cookii (Cook’s tussock grass) on a steep south-facing slope in Goodhope Bay during April 2015. Subsequent surveys in October 2015 and February 2016 confirmed breeding over a 1-ha area. In 2019/2020, breeding phenology and success was studied in 36 nests at the same site. Birds called from their burrows from mid-September, laying started in early October, and the first chick was observed on 20 December. Hatching peaked in early January and chicks fledged from the end of February to mid-March. This breeding phenology is similar to that at the neighbouring Crozet Archipelago. Overall nest survival was 46.4 ± 9.2% (mean ± SE; 95% CI: 29.5–64.1%), with most failures happening around hatching time. Further monitoring is needed to assess whether introduced House Mice Mus musculus contributed to the low hatching success. Common Diving Petrels were discovered breeding in other coastal areas, mostly in the south and east of the island. It is unlikely that breeding by this species was overlooked for three decades, suggesting that the elimination of cats allowed Common Diving Petrels to recolonise the island.

Leptin Promotes Primordial Follicle Activation by Regulating Ovarian Insulin-like Growth Factor System in Chicken.

Leptin and insulin-like growth factor 1 (IGF-1) regulate follicle development and reproduction in vertebrates. This study investigated the role played by leptin and IGF-1 in primordial follicle activation in the ovary of 7-day-old chicks. Different doses of leptin were intraperitoneally administrated to female layer chicks, and further analyses were performed. While leptin administration did not affect hepatic leptin receptor (LEPR), growth hormone receptor (GHR), or IGF-1, the lower dose of leptin significantly increased the messenger RNA (mRNA) expression of IGF-1, IGF-1 receptor, and IGF-binding protein (IGFBP)-2 and attenuated anti-Müllerian hormone (AMH) gene expression in the ovary. Furthermore, the ovaries of the same age chicks were challenged with leptin and/or IGF-1 in vitro. Leptin at a lower dose increased the mRNA expression of IGF-1, LEPR, and leptin; 100 ng/mL leptin and 10 ng/mL IGF-1 alone or combined with leptin reduced IGFBP-2 mRNA expression. AMH gene expression was also reduced by all doses except 10 ng/mL leptin. Histological studies showed that a lower dose of leptin injection induced the primordial follicle growth in the ovary in vivo, and the number of primordial follicles was higher in all leptin treatments over control in vitro. Moreover, the luciferase assay revealed that leptin enhanced IGF-1 promoter activity in LEPR-expressing CHO-K1 cells. Collectively, these results indicate that leptin directly affects the IGF-1/IGFBP system and promotes primordial follicular growth in the ovary of early posthatch chicks. In addition, the follicular development by leptin-induced IGF-1 is, at least in part, caused by the suppression of AMH in the ovary.

Phenotypic and Genotypic Characteristics of Antimicrobial and Disinfectant Resistance of Gram-negative Bacteria Involved in Early Broiler Chick Mortality

One of the most challenges facing the poultry industry in Egypt is the early mortality among broiler chicks during the first ten days of the rearing cycle, especially which caused by antimicrobial resistant Gram-negative bacteria. This study was conducted for the determination of the prevalence of Gram-negative bacteria involved in early mortality among broiler chicks. Antibiogram profile and antibiotic and disinfectant resistance genes were also performed. Five hundred samples (liver, yolk sac, cecum, spleen, and heart) from freshly dead affected chicks were cultured on different media for isolation of causative agents.by conventional and serological methods. PCR was used for detection of resistance genes. The Bacteriological examination revealed the presence of Salmonella spp., E. coli, and P. aeruginosa in the percentages of 23, 25 and 8%, respectively. Single and mixed infections were observed as 41, and 7%, respectively. 86.9% of Salmonella serovars were resistant to colistin sulphate, 48% of E. coli strains showed resistance against norfloxacin, and 87.5% of P. aeruginosa showed resistance against florfenicol. The mcr1 gene was found in 86.9% of all Salmonella serovar, qnrS gene was detected in 16% of E. coli, and floR gene was present in 100% of P. aeruginosa isolates. PCR screening for qacED1 revealed that all bacterial isolates under test were positive. It was concluded that results of current study assert the existence mcr1, qnrS, floR, and qacED1 genes among (Salmonella spp., E. coli, and P. aeruginosa) which were isolated from early aged broiler dead chicks; that represents a high risk on the poultry industry in Egypt.

Pathogenetic effects of feed intake containing of fumonisin (Fusarium verticillioides) in early broiler chicks and consequences on weight gain

Fusarium verticillioides is often responsible for contamination of poultry feed with the mycotoxin fumonisin. The objective of the study was to determine whether fumonisin-contaminated feed in the early phase of broiler chicks causes oxidative imbalances and interferes with weight gain. One-day-old male Cobb 500 broiler chicks (n = 80) were divided into four treatments of 20 birds each, all of which were fed basal feed until the 11th day of age. From day 12, some birds were challenged with fumonisin in the feed: Control (T0) continued receiving the basal ration; treatments T1, T2, and T3 were given feed experimentally contaminated with fumonisin at concentrations of 2.5 ppm, 5 ppm and 10 ppm, respectively. After the 5th (day 17) and 10th (day 21) days, ten birds from each treatment were euthanized for blood and tissue collection to measure histopathological, biochemical and oxidative stress markers. All animals were weighed individually at the beginning of the experiment (day 12), and at 17 and 21 days of age. Birds that ingested 10 ppm of fumonisin (T3) had lower (P < 0.05) weight gain compared to those in T0. At 21 days, the body weights of the T1, T2 and T3 chicks were 1.3%, 8.97% and 18.7% lower, respectively, than those of T0. No histological lesions in the livers were observed for any treatment; however, higher levels of reactive oxygen species (ROS: day 21) and lipoperoxidation (LPO: days 17 and 21) were observed, associated with lower liver activity of the enzymes superoxide dismutase (SOD: day 21), glutathione peroxidase (GPx: day 17 and 21) and glutathione S-transferase (GST: day 21) when birds consumed 5 or 10 ppm of fumonisin. In serum, LPO levels and SOD and GPx activities were lower for groups consuming high doses of fumonisin in the diet (T2 and T3); ROS levels and GST activity were higher in these birds. Birds that consumed fumonisin-containing diets had lower levels of alanine aminotransferase, total protein and albumin (T3); as well as lower serum glucose levels (days 17 and 21), uric acid and triglycerides (day 21) in T3 than in T0. At 21 days, there were smaller crypt sizes and intestinal villi in birds that consumed high levels of fumonisin. These results suggest that fumonisin (10 ppm) in chick diet causes hepatic oxidative stress and impairs intestinal health, consequently negatively affecting weight gain.

Effect of Hatching Time on Yolk Sac Percentage and Broiler Live Performance

ABSTRACT This study investigated the effects of broiler chick hatching time on the percentage of the yolk sac and subsequent broiler live performance. Broiler hatching eggs were obtained from a commercial flock at 55 wk of age and were stored for 2 d at 18°C and 75% relative humidity (RH) prior to incubation. Chicks were identified as hatching Early (471-477 h), Middle (480-486 h), and Late (494-510 h). All chicks were removed from the trays at 510 h of incubation. Body weight (BW) and yolk weight (YW) were determined at emergence from the shell (initial hatch time) and at placement on feed. Chicks were permanently identified by hatch time with neck tags, feather sexed, weighed, and introduced to feed and water in litter floor pens. Broiler BW and feed consumption (FC) were then determined 7, 21, and 35 d of age. Mortality was recorded daily. Although the percentage of the yolk was similar at hatch time, it was less in Early compared to Middle and Late chicks at placement (p≤0.05). Broiler chick BW was greater at placement in Late chicks compared to Early and Middle chicks (p≤0.05) but this advantage disappeared by 7 d because Late chicks consumed less feed to 7 d (p≤0.05). Early hatched broilers exhibited greater BW than Late with Middle broilers intermediate at 35 d (p≤0.05). There were no significant differences in feed consumption and feed conversion ratio (FCR) at 35 d of age. Additionally, late hatch chicks exhibited greater mortality. Overall, live performance of Late hatching chicks, judged by mortality and BW at 35 d, was reduced compared to Early hatching chicks.

Identification of cells expressing OLFM4 and LGR5 mRNA by in situ hybridization in the yolk sac and small intestine of embryonic and early post-hatch chicks

The chicken yolk sac (YS) and small intestine are essential for nutrient absorption during the pre-hatch and post-hatch periods, respectively. Absorptive enterocytes and secretory cells line the intestinal villi and originate from stem cells located in the intestinal crypts. Similarly, in the YS, there are absorptive and secretory cells that presumably originate from a stem cell population. Leucine-rich repeat containing G protein-coupled receptor 5 (Lgr5) and olfactomedin 4 (Olfm4) are 2 widely used markers for intestinal stem cells. The objective of this study was to map the distribution of putative stem cells expressing LGR5 and OLFM4 mRNA in the chicken small intestine from the late embryonic period to early post hatch and the YS during embryogenesis. At embryonic d 11, 13, 15, 17, and 19, the YS was collected (n = 3), and small intestine was collected at embryonic d 19, d of hatch (doh), and d 1, 4, and 7 post hatch (n = 3). Cells expressing OLFM4 and LGR5 mRNA were identified by in situ hybridization. In the YS, cells expressing only LGR5 and not OLFM4 mRNA were localized to the vascular endothelial cells lining the blood vessels. In the small intestine, cells in the intestinal crypt expressed both LGR5 and OLFM4 mRNA. Staining for OLFM4 mRNA was more intense than LGR5 mRNA, demonstrating that Olfm4 is a more robust marker for stem cells than Lgr5. At embryonic d 19 and doh, cells staining for OLFM4 mRNA were already present in the rudimentary crypts, with the greatest staining in the duodenal crypts. The intensity of OLFM4 mRNA staining increased from doh to d 7 post hatch. Dual label staining at doh for the peptide transporter PepT1 and Olfm4 revealed a population of cells above the crypts that did not express Olfm4 or PepT1 mRNA. These cells are likely progenitor transit amplifying cells. Thus, avians and mammals share similarity in the ontogeny of stem cells in the intestinal crypts.

Insulin-induced hypoglycemia associations with gene expression changes in liver and hypothalamus of chickens from lines selected for low or high body weight

Chickens selected for low (LWS) or high (HWS) body weight for more than 56 generations now have a 10-fold difference in body weight at 56days of age and correlated responses in appetite and glucose regulation. The LWS chickens are lean and some are anorexic, while the HWS are compulsive feeders and have a different threshold sensitivity of food intake and blood glucose to both central and peripheral insulin, respectively. We previously demonstrated that at 90-days of age, insulin-induced hypoglycemia was associated with reduced glucose transporter expression in the liver of both lines, and differences in expression of neuropeptide Y (NPY) and NPY receptor sub-type genes between LWS and HWS in the hypothalamus. The objective of this study was to determine effects of insulin-induced hypoglycemia on gene expression in the hypothalamus and liver of early post-hatch LWS and HWS chicks. On day 5 post-hatch chicks from each line were fasted for 3h and injected intraperitoneally with insulin or vehicle. At 1h post-injection, chicks were euthanized, blood glucose was measured, and hypothalamus and liver were removed. Total RNA was isolated and real time PCR performed. Insulin injection was associated with a more pronounced reduction in blood glucose in HWS compared with LWS chicks (two-way interaction; P<0.05). Aromatic L-amino acid decarboxylase, NPY, and NPY receptor sub-types 2 and 5 mRNA quantities were greater in LWS than HWS chicks in the hypothalamus (P<0.05), whereas pro-opiomelanocortin mRNA was greater in the hypothalamus of HWS than LWS (P<0.05). In the liver, glucose transporter 1, 2 and 3 (GLUT 1, 2 and 3, respectively) mRNA abundance was greater in HWS than LWS chicks (P<0.05). Compared to the vehicle, insulin treatment was associated with an increase in tryptophan hydroxylase 2 mRNA in the hypothalamus of both lines (P=0.02). In the liver of both lines, insulin treatment was associated with decreased (P=0.01) GLUT2 mRNA and increased (P=0.01) GLUT1 mRNA, compared to vehicle-treated chicks. Results suggest that NPY-associated factors and glucose transporters are differentially-expressed between LWS and HWS chickens and that HWS chicks display greater sensitivity to exogenous insulin during the early post-hatch period.

Global Warming May Depress Avian Population Fecundity by Selecting Against Early-Breeding, High-Quality Individuals in Northern Populations of Single-Brooded, Long-Lived Species

Global climate is changing at an unprecedented rate. Adjustments to breeding phenology represent responses to current climate change, and some climatic effects have negatively affected population reproductive performances. Here we simulated the possibility that climate warming-induced changes in the timing of egg-laying may modify the phenotype composition (i.e. proportion of high- vs. low-quality phenotypes) of avian populations of single-brooded, long-lived species in northern countries (where asymmetric changes of weather conditions are more pronounced), therefore affecting the internal structure and long-term stability of populations. In northern countries, prelaying temperatures have risen and laying and hatching are expected to occur earlier. However, because post-hatching temperatures have remained stable, early chicks hatch under conditions of low temperature and great precipitation, and may face increased mortality. Because early breeders are generally high-quality individuals, their contribution to the future recruitment of the breeding population will decrease, engendering a doubly negative effect: (1) the number of offspring in a population will be lower than in the past because of higher mortality in the largest broods; and (2) the population will increasingly be composed of the offspring of low-quality individuals, which will consequently decrease fitness of the entire population.

In ovo carbohydrate supplementation modulates growth and immunity-related genes in broiler chickens.

A study was undertaken to investigate the role of in ovo administrated carbohydrates on the expression pattern of growth and immune-related genes. In ovo injections (n = 400) were carried out on the 14th day of incubation into the yolk sac/amnion of the broiler chicken embryos. Expression of growth-related genes: chicken growth hormone (cGH), insulin-like growth factor-I & II (IGF-I & II) and mucin were studied in hepatic and jejunum tissues of late-term embryo and early post-hatch chicks. Expression of candidate immune genes: Interleukin-2, 6, 10 and 12 (IL-2, IL-6, IL-10 and IL-12), Tumour necrosis factor-alpha (TNF-α) and Interferon gamma (IFN-γ) were studied in peripheral blood monocyte cells of in ovo-injected and control birds following antigenic stimulation with sheep RBC (SRBC) or mitogen concanavalin A (Con-A). Glucose injection significantly increased the expression of IGF-II gene during embryonic period and both cGH and IGF-II in early post-hatch period, while ribose-injected chicks had higher expression of IGF-II gene during embryonic stage. Enhanced mucin gene expression was also observed in fructose-injected chicks during embryonic age. Glucose-injected chicks had higher expression of IL-6 or IL-10, while those injected with fructose or ribose had higher expression of IL-2, IL-12 and IFN gamma. It is concluded that in ovo supplementation of carbohydrates might help in improving the growth of late-term embryos and chicks. In ovo glucose could modulate humoral-related immunity, while fructose or ribose might help in improving the cellular immunity in broiler chickens.

An immunohistochemical study of enteric nervous system in the chick model.

The chick model is a useful research tool to investigate the development of the enteric nervous system (ENS). Recognition of appropriate markers for detection of chick enteric ganglia will allow better utilization of this model to study abnormalities of the ENS. This study aimed to validate a set of antibodies for avian ENS studies on wax sections. The specimens were taken from jejunum and colorectum of early post-hatching chicks, fixed in 4% buffered formaldehyde and stained using haematoxylin and eosin (H&E). Glial fibrillary acidic protein (GFAP), neuron specific enolase (NSE), synaptophysin and S-100 immunohistochemical biomarkers were employed on paraffin-embedded blocks to identify enteric ganglia. The immuno-reactivity scoring was recorded using a semi-quantitative fourtiered system (0, 1+, 2+, and 3+). In jejunum specimens, the immune-reactivity of GFAP was significantly higher than both synaptophysin (p=0.001) and S-100 (p=0.001). There was also a significant difference (p=0.03) between the immune-reactivity induced by NSE and S-100 in the jejunum samples. Significant differences were observed between GFAP immuno-reactivity and both synaptophysin and S-100 (p=0.013; and p =0.005, respectively) in the samples collected from colorectum. The level of immuno-reactivity between NSE and both synaptophysin and S-100 biomarkers in the colorectal specimens were also different significantly (p=0.02 and 0.007,respectively). The results of the present work showed that GFAP and NSE biomarkers can be used with high immuno-reactivities to examine the chick enteric ganglia as an appropriate animal model in ENS developmental disorders.

Effects of feeding fermented Ginkgo biloba leaves on small intestinal morphology, absorption, and immunomodulation of early lipopolysaccharide-challenged chicks

Aspergillus niger-fermented-Ginkgo biloba leaves (FG) and the comparative effect with nonfermented (NF)-Ginkgo leaves were investigated on morphology, absorption, and immunity of small intestine after lipopolysaccharide (LPS)-challenge in chicks at an early age. Broiler chicks (180 d of age) were divided into 3 treatment groups and were fed 1 of 3 diets: basal diet or basal diet supplemented with 0.5% NF or FG (control, NF, and FG group, respectively). Half of the birds from each treatment group were injected intraperitoneally with LPS (500 μg/kg of BW) or 0.9% NaCl solution (the sham control groups) at 10, 12, 15, 17, 19, and 21 d of age. The results indicated that when LPS-challenged birds were pretreated with FG, the decrease of ADG, ADFI, duodenal and jejunal relative weights, villus height, crypt depth, alkaline phosphatase activity, and plasma d-xylose were dramatically attenuated (P < 0.05 or P < 0.01). Meanwhile, a significant decrease (P < 0.05 or P < 0.01) of duodenal and jejunal interferon-γ, interleukin (IL)-4, IL-13, IL-18, inducible nitric oxide synthase, and duodenal sodium glucose co-transporter 1 mRNA expressional levels were found in LPS-challenged birds pretreated with FG. In conclusion, FG-supplemented diets minimized the deleterious effects of LPS and improved intestinal development, absorption, and immunity in immune-stressed chickens.

Physiological relationships of the early posthatch performance of broilers to their embryo and eggshell characteristics

Relationships between physiological parameters of early posthatch chicks with their corresponding egg and embryo parameters were examined in progeny of young broiler breeders. Four hundred and 80 broiler hatching eggs that were obtained from a 29-wk-old Ross 308 breeder flock were incubated on 8 replicate tray levels of an incubator until hatch. Between 10.5 and 18.5 d of incubation, internal (T(emb)) and external (T(ext)) egg temperatures were recorded twice daily using temperature transponders. Beginning at 18.5 d, the eggs were individually monitored for hatch every 12 h. Average T(emb), T(ext), and average daily incubational egg weight loss (EWL) for the 10.5- to 18.5-d incubation period were used to calculate eggshell water vapor conductance (G(H2O)), specific G(H2O) (g(H2O); G(H2O) adjusted to 100 g of set egg weight basis), and a G(H2O) constant (K(H2O)) for each egg. Chicks were grown out for 10 d in pens of a single battery brooder. In each pen, on d 3 posthatch, carcasses, yolk sac, liver, and pipping muscle samples were collected from at least 2 chicks that hatched from eggs implanted with transponders for determination of their relative weights and moisture concentrations. Livers and pipping muscles were also analyzed for glucose, glycogen, fat, and protein concentrations. Yolk sac weight as a percentage of chick BW (YW) and its moisture concentration (YSM) were positively correlated with T(emb). Egg g(H2O) was positively correlated with chick carcass moisture concentration and its relative weight as a percentage of set egg weight, but it was negatively correlated with YW. The positive functional relationship between T(emb) and incubation length may be mediated via their common positive relationships to YSM. A negative correlation was observed between percentage EWL and relative BW on d 0 and 0.5 posthatch for chicks hatched from unimplanted eggs. The results suggest that a higher g(H2O) results in an increased metabolism of the broiler embryo, which subsequently increases growth and yolk sac absorption in broiler chicks through 3 d posthatch.

Seasonal changes of the at‐sea distribution and food provisioning in rhinoceros auklets

AbstractCentral‐place foraging seabirds increase food‐loads and decrease meal frequency when they forage in areas that are distant from the breeding colony. In 2001–2002, we studied the seasonal changes in at‐sea distribution, food‐load mass, meal frequency, and fledging mass in rhinoceros auklets (Cerorhinca monocerata), which forage in coastal waters during the day and feed their chicks at night. In both years, greater numbers of auklets were observed flying in northern waters that are more distant from the colony in June (65 km) and July (65–66 km) than in May (38–47 km). In July of both years, many auklets flew northward across the transect set 65–120 km north of the colony at sunrise; the birds returned south again at sunset, indicating that they foraged in waters outside the study area. This seasonal northward movement of the foraging area may reflect the migration of their main prey item, the Japanese anchovy (Engraulis japonicus), which move with the Tsushima Warm Current flowing from the southern Sea of Japan. Food‐load mass did not increase seasonally. In both years, the estimated daily meal frequency was lower in July than in May or June, partly because of the increased foraging distance in July. Late‐hatched chicks also displayed lighter fledging masses than early chicks in both years. We suggest that late breeders are required to forage at great distances for longer periods, which may result in decreased meal frequency and lighter fledging mass of their chicks.

Effects of a Newly Developed Early Post-hatch Feed for Poultry Hatchlings on the Performance of Poultry

Usually, 24h or sometimes more are necessary for hatchlings to arrive at farms after hatching. During this period, the chicks are supplied neither feed nor water. To overcome the disadvantages caused by the long-term fasting, a new early post-hatch feed named ‘Chick-aide’ was developed, which was moistened before use and used in hatcheries and at farms. Extruded pellets of 2.5mm in diameter were produced using natural feed ingredients. This contained 3.05McalME/kg, 30.7%CP and 11.2%CF at mash base before extrusion. Chicks were usually supplied with 200g of ‘Chick-aide’ per 100 birds in the hatcheries and 100g at farms. With the trials in experimental houses, ‘Chick-aide’ increased intestinal weight of newly hatched layer male chicks by 62.4 or 42.0% at 24h after feeding, compared to the 24h fasted group. Intestinal length was also increased by 12.6%. The chicks supplied with ‘Chick-aide’ on the day of hatch and after 24h at farms showed increased body weight by 5.7% at 1 week and 4.4% at 2 weeks age compared to the control. In a field trial with 10,000 layer hatchlings, ‘Chick-aide’ increased body weight by 6.9% at 1 week age in comparison to control chicks treated in a customary manner. Other field trials with 10,000 small sized broilers produced by immature breeders and 9,400 ordinary broilers showed that the body weight of small male chicks was increased by 150g at nearly shipping age (51 days) and that of ordinary chicks by 190g (52 days) with ‘Chick-aide’, compared to the control. The results showed that ‘Chick-aide’ developed intestine of early post-hatch chicks remarkably and improved the subsequent growth. Benefit vs cost calculation for broilers suggested that ‘Chick-aide’ was cost-effective. The early post-hatch feeds such as ‘Chick-aide’ which supply hatchlings with nutrients and water together are considered to be essential for the maximum poultry performance.

Factors affecting the solution of a parental dilemma in albatrosses: at what age should chicks be left unattended?

With rare exceptions, avian offspring are continuously attended by one parent for at least the first few days after hatching. The duration of this phase of the nesting cycle is regulated by a trade-off between the benefits of brooding/guarding and those of foraging. We manipulated offspring age in grey-headed albatrosses, Thalassarche chrysostoma, by swapping chicks between nests. Parents given chicks 6 days older than their own shortened brooding by only 1.2 days, and parents given chicks 6 days younger than their own extended brooding by 1.4 days. Despite being relatively unresponsive to chick age, parents adjusted brooding in relation to calendar date and to chick condition. The results suggest that adults do not use chick age per se as a cue, but instead probably use an internal timer, and fine-tune the decision to end brooding according to date and chick mass. The duration of brood guarding did not correlate with adult body condition, suggesting that adults had a sufficient safety margin to allow them to respond to chick needs without compromising their own residual reproductive value. Chick survival at the end of brood guarding was strongly dependent on calendar date (early and late chicks suffered higher mortality), which suggests that grey-headed albatrosses benefit from breeding synchronously. We conclude that the length of the brood-guarding period is dependent on chick condition and seasonal variation in chick predation risk.

Ephrin A2 May Play a Role in Axon Guidance during Hair Cell Regeneration

Hair cell regeneration in the avian cochlea is accompanied by frequency specific reinnervation and recovery of physiologic function. The molecular cues that guide ganglion cells to tonotopically appropriate new hair cells have not been identified. We investigated the potential of ephrin A2 in this process. Ephrin A2 expression was characterized in acoustic ganglion cells of normal and gentamicin-treated early post hatch chicks. Ephrin A2 expression was determined by Western analysis of total protein isolated from acoustic ganglia in normal animals. Protein localization was characterized by fluorescence immunohistochemistry in sections of acoustic ganglia of normal and gentamicin treated animals. Patterns of ephrin A2 expression in acoustic ganglia were determined and quantified during hair cell regeneration. Ephrin A2 expression was found in acoustic ganglia by Western analysis. Localization of this protein by immunofluorescence revealed its presence in acoustic ganglion cells in normal chicks. After gentamicin treatment, ephrin A2 expression was lost in a subset of acoustic ganglion cells. The spatial and temporal pattern of ephrin A2 loss coincides with the pattern of hair cell loss and regeneration. The changes in ephrin A2 immunoreactivity in acoustic ganglion cells during cochlear damage and regeneration suggests that ephrin A2 may be involved in the guidance of ganglion cells to tonotopically appropriate hair cell targets during regeneration. Ephrin A2 in hair cell regeneration.

Relationships among prehatch and posthatch physiological parameters in early nutrient restricted broilers hatched from eggs laid by young breeder hens

The objective of this study was to establish relationships among various physiological parameters in early (through 72 h posthatch) nutrient restricted broiler chicks from young breeder hens. Despite a 19% decrease in mean BW between 0 and 72 h posthatch, there were no chick mortalities. Liver glycogen peaked at 24 h, and peaks in rectal temperature, plasma glucose, and plasma refractive index occurred at 48 h. By 24 h, negative correlations were noted between BW and relative liver weight and between liver glycogen and both refractive index and rectal temperature. By 24 h, positive correlations were noted between relative liver weight and liver glycogen, BW and plasma glucose, rectal temperature and plasma glucose, and rectal temperature and body fat loss score. Mean daily relative egg weight loss between 0 and 19 d of incubation (RIEWL) was positively correlated with rectal temperature at 0 h but was negatively correlated with rectal temperature at 24 h and liver glycogen at 24 and 48 h. Furthermore, mean relative hatching chick weight (RHCW) had significantly positive correlations with plasma glucose at 6 h and rectal temperature at 48 and 72 h. Broilers having a greater RHCW after hatching from eggs with a lower RIEWL may maintain higher metabolic rates between 24 and 72 h posthatch despite nutrient deprivation. However, broiler chicks from eggs exhibiting a higher than optimal RIEWL may have greater dependence on gluconeogenesis, thus requiring stricter management during initial brooding.

Maternal dietary conjugated linoleic acid alters hepatic triacylglycerol and tissue fatty acids in hatched chicks

The effects of feeding CLA to hens on newly hatched chick hepatic and carcass lipid content, liver TAG accumulation, and FA incorporation in chick tissues such as liver, heart, brain, and adipose were studied. These tissues were selected owing to their respective roles in lipid assimilation (liver), as a major oxidation site (heart), as a site enriched with long-chain polyunsaturates for function (brain), and as a storage depot (adipose). Eggs with no, low, or high levels of CLA were produced by feeding hens a corn-soybean meal-basal diet containing 3% (w/w) corn oil (Control), 2.5% corn oil + 0.5% CLA oil (CLA1), or 2% corn oil + 1.0% CLA oil (CLA2). The egg yolk content of total CLA was 0.0, 1.0, and 2.6% for Control, CLA1, and CLA2, respectively (P< 0.05). Maternal dietary CLA resulted in a decrease in chick carcass total fat (P < 0.05). Liver tissue of CLA2 chicks had the lowest fat content (P < 0.05). The liver TAG content was 8.2, 5.8, and 5.1 mg/g for Control, CLA1, and CLA2 chicks, respectively(P < 0.05). The chicks hatched from CLA1 and CLA2 incorporated higher levels of cis-9,trans-11 CLA in the liver, plasma, adipose, and brain than Control (P< 0.05). The content of 18:0 was higher in the liver, plasma, adipose, and brain of CLA1 and CLA2 than Control (P< 0.05), but no difference was observed in the 18:0 content of heart tissue. A significant reduction in 18:1 was observed in the liver, plasma, adipose, heart, and brain of CLA1 and CLA2 chicks (P< 0.05). DHA (22:6n-3) was reduced in the heart and brain of CLA1 and CLA2 chicks (P < 0.05). No difference was observed in carcass weight, dry matter, or ash content of chicks (P> 0.05). The hatchabilities of fertile eggs were 78, 34, and 38% for Control, CLA1, and CLA2, respectively (P< 0.05). The early dead chicks were higher in CLA1 and CLA2 than Control (18 and 32% compared with 9% for Control), and alive but not hatched chicks were 15 and 19% for CLAl and CLA2, compared with 8% for Control (P < 0.05). Maternal supplementation with CLA leads to a reduction in hatchability, liver TAG, and carcass total fat in newly hatched chicks.

Rates and consequences of relaying in Cassin's auklets Ptychoramphus aleuticus and rhinoceros auklets Cerorhinca monocerata breeding in a seasonal environment

We removed first eggs from early‐laying females to measure rates and consequences of relaying in Cassin's auklets Ptychoramphus aleuticus and rhinoceros auklets Cerorhinca monocerata at Triangle Island, British Columbia, Canada. Based on egg size and composition, the investment that Cassin's auklets made in first eggs was very close to that predicted from adult body mass, whereas rhinoceros auklets invested more. In both species, a high percentage of females relaid (90% of Cassin's and 87% of rhinoceros auklets). Breeding success declined weakly with later laying among control Cassin's auklet pairs, but pairs that we induced to relay bred more successfully than naturally late pairs, and similar to values predicted from laying dates of their first eggs. Their chicks also fledged heavier and younger than late control chicks, and similar to values in early control chicks, but followed the population‐wide seasonal decline in wing length at fledging. Nestling diets were dominated by Neocalanus copepods until late in the season, a sign that feeding conditions remained favourable until late. In contrast, rhinoceros auklet pairs induced to relay followed the population‐wide seasonal decline in breeding success, which was driven by a decline in hatching success. Pacific sandlance Ammodytes hexapterus, thought to be a preferred prey species, virtually disappeared from nestling diets in mid‐to‐late season, yet there was no seasonal decline in fledging mass. However, chicks from replacement eggs followed the declines among control chicks in both age and wing length at fledging. Despite the female having produced a replacement egg, and despite delayed breeding, there appeared to be little immediate consequence associated with relaying for Cassin's auklets, except for a tendency for their chicks to fledge with short wings. Consequences were more marked in rhinoceros auklets (greatly reduced hatching success, and having their chicks fledge with short wings), and this may have been due to the large investment made in eggs, and/or to delayed breeding. Results of this study show that attributes of Cassin's and rhinoceros auklets that lay at different times in the season can be important in driving seasonal declines in breeding performance, as found in studies on other Alcidae. They also show how decisions taken during the egg stage can have variable yet potentially important implications for fitness, even in relatively long‐lived species that lay single‐egg clutches.