Chick Survival Rates Research Articles

Comparative fertility and hatchability of broiler grandparent stocks in Bangladesh

Checking the fertility and hatchability of broiler grandparent lines is important for improving chicken production. The Cobb-500, Ross-308, and Indian River (IR) grandparent strains were studied to determine their initial egg weight, fertility, hatchability, embryonic mortality, hatching weight, and chick survival rates. We studied a total of 2700 eggs from three different age/treatment, each consisting of three replicates with 100 eggs for each of the three genotypes. Using an automated incubator, eggs were incubated. Cobb-500 had a significantly higher mean egg weight (67.52 g) at later stage of their age compared to Ross-308 (64.22 g) and IR (65.05 g). Study also found that a higher egg weight reflects a higher day-old chick weight. The fertility rates of the Ross-308, IR, and Cobb-500 genotypes were high at 35 weeks (96.00%, 87.00%, and 93.00%) but declined after 45 weeks (64.22%, 65.05%, and 67.52%), respectively. The hatchability of Ross-308, IR, and Cobb-500 eggs at 35 weeks was 85.00%, 75.00%, and 80.00%, respectively. By 45 weeks, all genotypes had higher hatchability, with Ross-308 having the highest at 89%. But at 55 weeks, all genotype showed lowest hatchability where IR was the lowest 67%. Statistically significant variations were observed across strains at later stage. As age increased, embryonic mortality and brood mortality were higher. Compared to the other two, Ross-308 showed the lowest mortality in both embryonic and brooding cases in all three stages of their age of life. However, the IR breed consistently displayed the highest mortality rate. Same pattern showed dead in shell and culling chick’s percentages. Strain-wise, the parameters differ from each other. However, regarding overall performance, the Ross-308 strain outperformed the other two strains. Asian Australas. J. Food Saf. Secur. 2024, 8(2), 48-57

Social determinants of success of community-based hornbill conservation in Thailand

The Thailand Hornbill Project (THP) launched the first community-based hornbill conservation program in southern Thailand (CBC-THP) in 1994 to combat hornbill poaching. For 30 years, CBC-THP has engaged local communities in hornbill conservation, achieving ecological success evident through increased chick survival rates. To evaluate CBC-THP's success beyond ecological outcomes, we surveyed three stakeholder groups: 124 hornbill adopters (HA), 142 participants in CBC-THP (THPP), and 422 non-participants (NTHPP). We examined their backgrounds, eight social determinants, and their perceptions of CBC-THP's success. Using explanatory factor analysis, we categorized specific social determinants for comparison and assessed their impact on perceived success through ordinal regression. The analysis revealed that perceived outcomes were a primary determinant of success across all groups. For HAs, involvement in CBC-THP was a significant factor, whereas for THPP and NTHPP, knowledge of hornbill ecology and a positive attitude towards conservation efforts were crucial. Additionally, perceived benefits substantially influenced THPP's view of success, while trust, perceived conflict, and barrier to sustainability were key factors for NTHPP. These findings highlight the importance of understanding social factors to foster stakeholder support for community-based wildlife conservation initiatives. We recommend a nationwide assessment of CBC-THP's perceived success to further explore social factors affecting hornbill conservation.

The Broad-Spectrum Endolysin LySP2 Improves Chick Survival after Salmonella Pullorum Infection.

Salmonella pullorum causes typical "Bacillary White Diarrhea" and loss of appetite in chicks, which leads to the death of chicks in severe cases; thus, it is still a critical issue in China. Antibiotics are conventional medicines used for Salmonella infections; however, due to the extensive long-term use and even abuse of antibiotics, drug resistance becomes increasingly severe, making treating pullorum disease more difficult. Most of the endolysins are hydrolytic enzymes produced by bacteriophages to cleave the host's cell wall during the final stage of the lytic cycle. A virulent bacteriophage, YSP2, of Salmonella was isolated in a previous study. A Pichia pastoris expression strain that can express the Salmonella bacteriophage endolysin was constructed efficiently, and the Gram-negative bacteriophage endolysin, LySP2, was obtained in this study. Compared with the parental phage YSP2, which can only lyse Salmonella, LySP2 can lyse Salmonella and Escherichia. The survival rate of Salmonella-infected chicks treated with LySP2 can reach up to 70% and reduce Salmonella abundance in the liver and intestine. The treatment group showed that LySP2 significantly improved the health of infected chicks and alleviated organ damage caused by Salmonella infection. In this study, the Salmonella bacteriophage endolysin was expressed efficiently by Pichia pastoris, and the endolysin LySP2 showed good potential for the treatment of pullorum disease caused by Salmonella pullorum.

Culturing the Chicken Intestinal Microbiota and Potential Application as Probiotics Development.

Pure cultures of chicken intestinal microbial species may still be crucial and imperative to expound on the function of gut microbiota, and also contribute to the development of potential probiotics and novel bioactive metabolites from gut microbiota. In this study, we isolated and identified 507 chicken intestinal bacterial isolates, including 89 previously uncultured isolates. Among these, a total of 63 Lactobacillus strains, belonging to L. vaginalis, L. crispatus, L. gallinarum, L. reuteri, L. salivarius, and L. saerimneri, exhibited antibacterial activity against S. Pullorum. Acid tolerance tests showed Limosilactobacillus reuteri strain YPG14 (L. reuteri strain YPG14) has a particularly strong tolerance to acid. We further characterized other probiotic properties of L. reuteri strain YPG14. In simulated intestinal fluid, the growth of L. reuteri strain YPG14 remained stable after incubation for 4 h. The auto-aggregation test showed the auto-aggregation percentage of L. reuteri strain YPG14 was recorded as 15.0 ± 0.38%, 48.3 ± 2.51%, and 75.1 ± 4.44% at 3, 12, and 24 h, respectively. In addition, the mucin binding assay showed L. reuteri strain YPG14 exhibited 12.07 ± 0.02% adhesion to mucin. Antibiotic sensitivity testing showed that L. reuteri strain YPG14 was sensitive to the majority of the tested antibiotics. The anti-Salmonella Pullorum (S. Pullorum) infection effect in vivo revealed that the consumption of L. reuteri strain YPG14 could significantly improve body weight loss and survival rate of chicks infected by S. Pullorum; reduce the loads of S. Pullorum in the jejunum, liver, spleen, and feces; and alleviate the jejunum villi morphological structure damage, crypt loss, and inflammatory cell infiltration caused by S. Pullorum. Overall, this study may help us to understand the diversity of chicken intestinal microflora and provide some insights for potential probiotic development from gut microbiota and may find application in the poultry industry.

Evaluation of the efficacy of the antimicrobial peptide HJH-3 in chickens infected with Salmonella Pullorum.

As a promising substitute for antibiotics, increasing attention has been given to the clinical application of antimicrobial peptides (AMPs). In this study, the mode of action of the HJH-3 against Salmonella Pullorum was investigated. The structure and properties of HJH-3 were examined in silico, and minimum inhibitory concentrations (MICs) were determined to evaluate its antimicrobial spectrum. The time-kill kinetics of HJH-3 was determined. The hemolytic activity of HJH-3 was determined by measuring the hemoglobin ultraviolet absorption value, and the cytotoxicity was determined using a CCK-8 kit. The protective effect of HJH-3 on chickens infected with S. Pullorum was evaluated in vivo. The results demonstrated that HJH-3 exhibited strong antibacterial activity against Gram-negative pathogens at MIC values of 1.5625-25 μg/mL and against Gram-positive pathogens at MIC values of 25-50 μg/mL. HJH-3 also showed activity against the Candida albicans (100 μg/mL) and Bacillus subtilis (6.25-12.5 μg/mL). HJH-3 at 100 μg/mL completely killed S. Pullorum after co-incubation for 6 h. Likewise, the hemolysis rate of CRBCs treated with 100 μg/mL HJH-3 (7.31%) was lower than that of CRBCs treated with 100 μg/mL pexiganan (40.43%). Although the hemolysis rate of CRBCs treated with 400 μg/mL HJH-3 was increased to 13.37%, it was much lower than that of 400 μg/mL pexiganan (57.27%). In regards to cytotoxicity, HJH-3 had almost no-effect on the CEF proliferation, pexiganan decreased CEFs proliferation from 56.93 to 31.00% when increasing the concentration from 50 to 200 μg/mL. In a chicken infection model, the results showed that the antibiotic prevention and HJH-3 prevention groups exhibited the best treatment effect, with the chickens being protected from the lethal dose of S. Pullorum, a decreased number of bacteria in the blood and spleen, and less pathological changes in intestinal segments. The prevention of infection by HJH-3 was similar to that by Ampicillin; the effect of treatment after infection was lower than that of treatment before infection, and the survival rate of infected chicks treated with HJH-3 was 70%, which was still higher than that of the infected chickens. These results suggest that HJH-3 has good clinical application potential and can be used as a substitute for antibiotics for the prevention and treatment of S. Pullorum infection.

English

The study was conducted in 225 indigenous chicken keeping households between August 2020 and July 2021 in Machakos and Busia Counties. A semi-structured questionnaire was used to collect data on socio-economic factors, flock characteristics and management practices from targeted households. Overall, majority of respondents were male (82%) with formal education (87%). Agriculture was the main source of income for most households (71%). One third of the households accessed extension services (26%), market information (31%) and credit (33%). The extensive system of production was predominant (66%) with an average chicken flock size of 28 birds characterized by low chick survival rate (33%). There was selective adoption of management interventions, with 76% of households adopting feed supplementation and half (55%) adopted improved chicken housing. Lesser proportion of households practiced improved chick rearing (32%) and vaccinated their chicken (30%). Access to credit and literacy increased adoption of the management interventions (p<0.05). Adoption of management interventions such as improved chick rearing and housing increased chick survival and average chicken flock size significantly (p>0.05). The findings point to necessary targeted efforts such as improving farmer access to credit and provision of specifically packaged extension messages to meet needs of indigenous chicken farmers. Key words: Indigenous chicken, management interventions, adoption, socioeconomic factors.

Chick survival in a high-density Northern Lapwing (Vanellus vanellus) population on the river islets of the middle Pripyat River, Belarus

The field studies were conducted in three ephemeral river islets of the middle Pripyat River, southern Belarus in 2006–2007. Nestlings of the Northern Lapwing (Vanellus vanellus) were ringed soon after hatching, and reencountered during subsequent visits. Post-hatching survival was estimated by capture-mark-recapture models. Daily survival rates of the Northern Lapwing chicks were very high, varying between 0.90 and 0.99, and the cumulative survival rates over 35 days between hatching and fledging were 0.54 and 0.70 in 2006 and 2007, respectively. Survival rate was lower in the first ten days of life, which is similar to that reported in other precocial species. The key factor supporting this high breeding success is low predation due to nesting of lapwings on periodic river islets that naturally restrict access by mammalian predators and apparent scarcity of terrestrial and avian predators. River islet habitats with co-occurrence of dry and wet fertile microhabitats provide optimum feeding conditions for the Lapwing chicks with a wide range of aquatic, ground and surface invertebrates. Moreover, semicolonial breeding of the Northern Lapwing (about 30 nests/ha) with other waders, terns and gulls increases the effectiveness of anti-predator behaviour. Consequently as a result of low predation pressure and good foraging conditions, in 2006 and 2007, productivity was 2.1 and 2.8 fledged young per single nest with four chicks respectively, a value hardly reported in Europe, except in managed sites.

Demographic effects of a megafire on a declining prairie grouse in the mixed-grass prairie.

Recent studies have documented benefits of small, prescribed fire and wildfire for grassland-dependent wildlife, such as lesser prairie-chickens (Tympanuchus pallidicintus), but wildlife demographic response to the scale and intensity of megafire (wildfire >40,000 ha) in modern, fragmented grasslands remains unknown. Limited available grassland habitat makes it imperative to understand if increasing frequency of megafires could further reduce already declining lesser prairie-chicken populations, or if historical evolutionary interactions with fire make lesser prairie-chickens resilient. To evaluate lesser prairie-chicken demographic response to megafires, we compared lek counts, nest density, and survival rates of adults, nests, and chicks before (2014-2016) and after (2018-2020) a 2017 megafire in the mixed-grass prairie of Kansas, USA (Starbuck fire ~254,000 ha). There was a 67% decline in attending males on leks post-fire and a 57% decline in occupied leks post-fire. Despite population declines as indicated by lek counts, adult female breeding season survival ( ) was similar pre- ( =0.65 ± 0.08 [SE]) and post-fire (0.61 ± 0.08), as was chick survival (pre-fire: 0.23 ± 0.07; post-fire: 0.27 ± 0.11). Nest survival appeared lower post-fire (pre-fire: 0.38 ± 0.06; post-fire: 0.20 ± 0.06), but did not differ at the 95% confidence interval. Nest density of marked females declined 73% in areas burned by megafire. Although lesser prairie-chickens persisted in the study area and we documented minimal effects on most demographic rates, reduced lesser prairie-chicken abundance and reproductive output suggests full recovery may take >3 years. Increased propensity for megafire resulting from suppression of smaller fires, compounded by climate change and woody encroachment, may impose a short-term (3-5year) threat to already declining lesser prairie-chicken populations.

Contrasting bottom-up effects of warming ocean on two king penguin populations.

Breeding success is often correlated with climate, but the underlying bottom-up mechanisms remain elusive-particularly in marine environments. Consequently, conservation plans of many species often consider climate change as a unilateral threat, ignoring that even nearby populations can show contradicting trends with climate. Better understanding the relationship between climate and environment at different scales can help us interpret local differences in population trends, ultimately providing better tools to evaluate the global response of a species to threats such as global warming. We studied a growing king penguin population nesting at Kerguelen island (Southern Indian Ocean), hosting one of the largest colonies in the world. We used a unique dataset of foraging, breeding success, and climate data spanning over 25 years to examine the links between climate, marine environment, and breeding success at this colony. The results were then compared to the neighboring population of Crozet, which experienced the steepest decline for this species over the past few decades. At Crozet, penguins experienced lower breeding success in warmer years due to productive currents shifting away from the colony, affecting foraging behavior during chick rearing. At Kerguelen, while chick mass and survival experienced extreme variation from year to year, the annual variation was not associated with the position of the currents, which varied very little compared to the situation in Crozet. Rather than being affected by prey distribution shifts, we found evidence that chick provisioning in Kerguelen might be influenced by prey abundance, which seem to rather increase in warmer conditions. Furthermore, warmer air temperature in winter increased chick survival rate, likely due to reduced thermoregulation cost. Investigating the mechanisms between climate and fitness allowed us to predict two different fates for these populations regarding ongoing global warming.

Lacticaseibacillus rhamnosus alleviates intestinal inflammation and promotes microbiota-mediated protection against Salmonella fatal infections

The fatal impairment of the intestinal mucosal barrier of chicks caused by Salmonella significantly resulting economic losses in the modern poultry industry. Probiotics are recognized for beneficially influencing host immune responses, promoting maintenance of intestinal epithelial integrity, antagonistic activity against pathogenic microorganisms and health-promoting properties. Some basic studies attest to probiotic capabilities and show that Lacticaseibacillus rhamnosus could protect intestinal mucosa from injury in animals infected with Salmonella Typhimurium. However, the mechanisms underlying its protective effects in chicks are still not fully understood. Here, we used the chick infection model combined with histological, immunological, and molecular approaches to address this question. The results indicated that L. rhamnosus significantly reduced the diarrhea rate and increased the daily weight gain and survival rate of chicks infected with S. Typhimurium. Furthermore, we found that L. rhamnosus markedly improved the immunity of gut mucosa by reducing apoptotic cells, hence effectively inhibiting intestinal inflammation. Notably, pre-treatment chicks with L. rhamnosus balanced the expression of interleukin-1β and interleukin-18, moderated endotoxin and D-lactic acid levels, and expanded tight junction protein levels (Zonula occluden-1 and Claudin-1), enhanced the function of the intestinal mucosal epithelial cells. Additionally, investigations using full-length 16S rRNA sequencing also demonstrated that L. rhamnosus greatly weakened the adhesion of Salmonella, the mainly manifestation is the improvement of the diversity of intestinal microbiota in infected chicks. Collectively, these results showed the application of L. rhamnosus against Salmonella fatal infection by enhancing barrier integrity and the stability of the gut microbiota and reducing inflammation in new hatch chicks, offering new antibiotic alternatives for farming animals.

ON-FARM EVALUATION OF HAY BOX BROODER EFFECTIVENESS ON SASSO AND INDIGENOUS CHICKS

This study was conducted in South Gondar Zone to evaluate the effectiveness of hay-box chick brooder under rural farming condition with the use of Sasso and Indigenous day old chicks. Based on their voluntariness to construct the hay box brooder, fifteen households were selected purposively. A total of 150 indigenous and 450 Sasso T-44 day old chicks were divided equally in to 15 groups each with 10 indigenous and 30 Sasso day-old chicks. The Sasso groups were active and vigorous after the first week of hay box brooding: whereas the indigenous groups were found to be difficult to adapt to the hay box brooding environment and characterized by dull appearance, noisy voice/sound, huddling together, wing dropping, poor feed and water consumption and stunted growth throughout the brooding period. About 85 and 50% of Sasso and indigenous chicks survived at 8 weeks of age of hay box brooding respectively. Hay box brooding technology is effective in rising exotic baby chicks under rural Ethiopian conditions as compared to the performance of natural brooding. On the contrary, the survival rate of indigenous chicks assigned to the hay box brooder was comparable to that of natural brooding. Therefore, it seems that the hay box chick brooding technology is not adequately effective in raising indigenous chicks as measured by chick growth performance and rate of survival 8 weeks of age.

Development of a Vitamin A Deficient (VAD) Songbird

Vitamin A deficiency (VAD) is a global health problem with effects on brain function through altered retinoic acid signaling. However, the specific effect of VAD on speech and vocal‐motor learning has not been studied. Songbirds possess a cortical brain circuit for vocal learning that relies on retinoic acid signaling during the critical period of vocal learning. To study VAD in a vocal learner we developed a special diet from white rice and sunflower seed, two grains that are naturally low in vitamin A and carotenoids, with other essential vitamins and minerals added back. This diet was fed to zebra finch family groups during chick rearing to evaluate the ability of parents to feed the diet to their chicks and the effects of a VAD diet on serum and brain retinol, chick growth and development. We found that adult birds readily consumed the rice/sunflower seed diet and fed it to their nestlings. Adults that consumed the diet maintained the same caloric intakes compared to when fed a regular seed diet and although these birds showed some decline in body mass, it remained within a normal range. Surprisingly, we detected a 28% decline in serum retinol at three weeks on the VAD diet in adult finches, a response that makes songbirds a highly useful model to study VAD. Juveniles that were fed the diet by the adults beginning at hatch also were able to consume and thrive. Compared to controls, chicks on the VAD diet showed no effects on growth rate between 10‐65 days, but the chick survival rate was 63% lower than that of controls with no chicks surviving beyond 65 days old. Chicks that were on the VAD diet did not exhibit sub‐song behavior between 35‐50 days (72 total hours of monitoring), whereas chicks that were on a seed diet or a rice/sunflower seed control diet (with retinol added back) showed song development. We also note that VAD affected eye shape and appearance, consistent with what is found during VAD in non‐avian models. Serum retinol of chicks on the VAD diet showed a 57% decline compared to controls. Further development of this model will require titration of the VAD to moderate levels that allow for song development and high chick survival. This study lays the groundwork for the use of modified diets in the songbird model to examine how VAD or other micronutrients may modulate neural development in the vocal circuit of a vocal learner, as well as open the door for the use of the model in high‐fat diet nutrition experiments and lipid transport studies.

A comparative analysis of the breeding biology of the lesser whitethroat and chiffchaff (Passeriformes, Sylviidae) in habitats with different degrees of urbanization (South Minusinsk basin)

This paper presents the results of long-term observations of nesting of two species of warblers inhabiting territories with different degrees of urbanization Sylvia curruca and Phylloscopus collybita. The research was carried out in the steppe and forest-steppe zone of the South Minusinsk basin. Both species are common and nest both in natural habitats and in the built-up part of the city. The lesser whitethroat arranges nests in the shrub layer only. The chiffchaff warbler has nests in a grassy tier in its natural habitats. The authors have revealed differences in the time of nesting in different altitudinal vegetation zones, as well as interspecific differences. The sizes of nests, clutches and eggs for different populations and in different years are determined. These parameters show variability, but no dependence on the environmental situation for them has been revealed. The survival rate of eggs and chicks and the overall efficiency of reproduction are evaluated. All the studied indicators of nesting biology, identified among the two species of warblers, are within the limits characteristic of the species. The differences revealed for populations located in natural and urbanized territories are manifested at the level of behavior of individuals (the nature of the nest location) and at the biocenotic level (the causes of the death of clutches). The authors have found no signs of isolation of urban populations.

Correction to 'Bayesian inference reveals positive but subtle effects of experimental fishery closures on marine predator demographics'.

Correction to 'Bayesian inference reveals positive but subtle effects of experimental fishery closures on marine predator demographics'.

Warming Arctic summers unlikely to increase productivity of shorebirds through renesting

Climate change in the Arctic is leading to earlier summers, creating a phenological mismatch between the hatching of insectivorous birds and the availability of their invertebrate prey. While phenological mismatch would presumably lower the survival of chicks, climate change is also leading to longer, warmer summers that may increase the annual productivity of birds by allowing adults to lay nests over a longer period of time, replace more nests that fail, and provide physiological relief to chicks (i.e., warmer temperatures that reduce thermoregulatory costs). However, there is little information on how these competing ecological processes will ultimately impact the demography of bird populations. In 2008 and 2009, we investigated the survival of chicks from initial and experimentally-induced replacement nests of arcticola Dunlin (Calidris alpina) breeding near Utqiaġvik, Alaska. We monitored survival of 66 broods from 41 initial and 25 replacement nests. Based on the average hatch date of each group, chick survival (up to age 15 days) from replacement nests (Ŝi = 0.10; 95% CI = 0.02–0.22) was substantially lower than initial nests (Ŝi = 0.67; 95% CI = 0.48–0.81). Daily survival rates were greater for older chicks, chicks from earlier-laid clutches, and during periods of greater invertebrate availability. As temperature was less important to daily survival rates of shorebird chicks than invertebrate availability, our results indicate that any physiological relief experienced by chicks will likely be overshadowed by the need for adequate food. Furthermore, the processes creating a phenological mismatch between hatching of shorebird young and invertebrate emergence ensures that warmer, longer breeding seasons will not translate into abundant food throughout the longer summers. Thus, despite having a greater opportunity to nest later (and potentially replace nests), young from these late-hatching broods will likely not have sufficient food to survive. Collectively, these results indicate that warmer, longer summers in the Arctic are unlikely to increase annual recruitment rates, and thus unable to compensate for low adult survival, which is typically limited by factors away from the Arctic-breeding grounds.

The use of fractionated protein-vitamin flour from wheat bran in the diets of quails

The results of the experiment on the use of protein-vitamin flour from wheat bran, divided into fractions with particle size of 140, 400 and 800 µm in the diet of domesticated quails are presented. The experiment lasted for 60 days and was carried out according to the generally accepted methods on quails of the Japanese breed, formed in four similar groups (one control and three experimental), 80 heads each, at the age of one-day old. All groups received compound feed (the main diet), prepared taking into account the age and physiological characteristics of quails, but in the bird diet of the 1st, 2nd and 3rd experimental groups, part of the wheat (7%) was replaced with wheat protein-vitamin flour of three fractions with a particle size of 140, 400 and 800 µm, respectively. The poultry was kept in a battery cage under required microclimate conditions. The effect of feeding fractionated protein-vitamin flour from wheat bran was studied on the survival rate of quail chicks, their growth rate, indicators of meat productivity and hematological parameters, changes in the species composition of microorganisms of the gastrointestinal tract. The optimal fractions of wheat bran flour as the new feed in the diets of quails were determined in terms of efficiency of their productive and physiological action. The introduction of protein-vitamin flour from wheat bran into the compound feed of quails with a particle size of 140 and 400 µm in the amount of 7% of the grain part of the diet increased the survival rate of quail chicks by 3.0%, the average daily gain in live weight by 2.30 and 5.59%, the weight of eviscerated bird carcass by 4.5 and 6.16%, protein content in meat by 0.84 and 0.57%. Feeding the quails with flour of various fractions did not have a positive effect on the conversion of feed into produce. The biochemical parameters of the quail chicks’ blood remained within the physiological norm. Fractionated protein-vitamin flour with a particle size of 400 and 800 µm stimulated the growth of bifidobacteria, and with a particle size of 140 and 800 µm inhibited the development of Escherichia coli.

Coexistence without conflict, the recovery of Ireland\u2019s endangered wild grey partridge Perdix perdix

By 1995, Ireland’s wild grey partridge (Perdix perdix) was extinct nationally as a breeding species on farmland. The two populations remaining were confined to Ireland’s industrial cutaway peat bogs. One of these populations was deemed viable. In 1996, the National Parks and Wildlife Service of Ireland and the Irish Grey Partridge Conservation Trust established a conservation project to prevent the extirpation of this population. In this paper, we explore the impact of each management factor on two key demographic response variables: chick survival rates and the number of breeding pairs. The numbers of linear metres of nesting strips had the most significantly positive effect on spring pairs, followed by the total number of supplementary food hoppers and the total hectares of brood-rearing and over-winter cover. Counterintuitively, encounters with Hen Harriers (Circus cyaneus) did not negatively affect chick survival or the number of spring pairs. While we cannot rule out the contribution of each explanatory variable, none had a statistically significant effect on chick survival, suggesting there may be locally confounding factors that our model could not capture. The weather conditions during the peak hatching period had a significant influence on chick survival, with the average maximum temperature observed in June having the strongest positive association with an increase of 1 °C in the average maximum temperature in June associated with an increase in chick survival of 9.4% on average. Conversely, for every additional 1 mm of rain in June, there was a 0.23% drop in chick survival on average.

Bacillus subtilis BSH has a protective effect on Salmonella infection by regulating the intestinal flora structure in chickens

Salmonellosis is a worldwide zoonotic disease that poses a serious threat to the reproduction of livestock and poultry and the health of young animals. Probiotics including Bacillus species, have received increasing attention as a substitute for antibiotics. In this study, chicks infected with Salmonella were fed feed supplemented with the BSH to observe the pathological changes in the liver, detect the number of viable bacteria in the liver and spleen, and record the death of the chicks. The results showed that BSH could reduce the pathological changes in the liver and the invasion of Salmonella into the liver and spleen of chicks. In addition, the survival rate of chicks in the BSH experimental group was 60%, while that in the infected control group was 26%, indicating that BSH had a protective effect on chicks infected with Salmonella. Finally, the fecal microflora of 9-day-old chicks was analyzed by 16S rRNA high-throughput sequencing. The results showed that Salmonella infection could cause intestinal flora changes, while BSH could alleviate this change. In addition, BSH also promoted the proliferation of Lactobacillus salivarius in the cecum of chick. This study emphasized that BSH has anti- Salmonella infection effects in chickens and can be used as a candidate microecological preparation strain.

한국토종닭의 품종, 산란 연령 및 종란의 보관 기간이 병아리의 강건성에 미치는 영향

We investigated the effects of breed, laying age, and egg storage period on the vitality of chicks using the Hwanggalsaek Jaeraejong, Korean Rhode Island Red, and Korean White Leghorn chicken breeds. Their eggs were collected during the early laying period (27~29 weeks) and late laying period (50~52 weeks) and were stored for 3 days, 7 days and 14 days. After the eggs hatched, the hatching time, production performance, and organ weight of chicks were investigated. <i>IL-6</i> gene expression level and relative length of telomeres were analyzed to determine the physiological activity of the chicks. <i>HSP</i> gene expression level and heterophil to lymphocytes ratio were also analyzed to examine the degree of stress response in the chicks. The results showed that breed and laying age influenced the vitality of chicks, but the egg storage period did not. Korean Leghorn chicks were considered the weakest breed in terms of vitality owing to their low survival rate, small heart size, low physiological activity, and high stress response level. Although the survival rate of chicks produced in the early laying period was low, their high physiological activity and low stress response indicated that they had a high vitality than the chicks produced in the late laying period. In conclusion, to obtain chicks with high vitality, it would be desirable to select a high vitality breed and avoid the use of chicks produced in the late laying period.

Ecological value of different vegetated strip types in providing valuable insect-rich habitats for grey partridge chicks

The intensification and specialisation of agriculture has contributed to farmland wildlife decline, including farmland birds. Grey partridge is a farmland species which has experienced a significant decline across Europe in recent decades. Chick survival rate is a key determinant of grey partridge population change and depends essentially on the availability of insect food. In this study, ground-dwelling and canopy-dwelling insects were collected using pitfall trapping and sweep netting methodologies, respectively, on different strip types in an area established for the conservation of grey partridge. The aim was to further our understanding of the value of different vegetated strip types in providing insect-rich habitats for grey partridge chicks. Overall, wildflower strip (WS) provided the greatest insect abundance. Significantly more ground-dwelling insects were found on WS, natural regeneration (NS) and leguminous strips (LS) than on grass strip (GS). Canopy-dwelling insects were also significantly more abundant on WS compared to all other strip types. This study highlights that WSs may represent important habitats in providing insect-rich food for grey partridge chicks and sowing these strips may therefore play a key role in decreasing chick mortality and supporting grey partridge conservation. It also demonstrates that other different vegetated strip types may still provide strip-specific insect taxa, in addition to other valuable resources. This study recommends a complex mosaic of different strip types to provide key resources for grey partridge, such as insect and plant food, nesting habitats and overwinter cover.