Single Comb White Leghorn Chickens Research Articles

Causes of Normal Mortality in Commercial Egg-Laying Chickens.

In a large population of animals, it is normal to have some die each day from causes not related to disease, which is often referred to as natural causes. In poultry production, this phenomenon is commonly referred to as daily mortality. In egg-producing chickens, many of the natural causes of death are associated with making an egg. The causes of normal mortality in commercial egg-laying chicken flocks have been described very little to date. A commercial chicken egg farm, housing approximately two million single-comb white leghorn chickens (Gallus gallus domesticus) in 16 egg-producing flocks, was visited on a monthly basis to monitor bird health, body conditioning, skeletal integrity, and causes of daily mortality in an attempt to provide early detection of health abnormalities. A representative sample of daily mortality from each flock was necropsied to determine the cause of death. Reported herein is a summary of visits for a period of 38 mo from June 2011 to July 2014. The top 15 causes of normal mortality, in rank order of prevalence, were determined to be the following: egg yolk peritonitis, hypocalcemia, gout, self-induced molt, salpingitis, caught by spur, intussusception or volvulus (twisted intestine), cannibalism (pick out), tracheal plug, septicemia, fatty liver syndrome, internal layer, layer hepatitis, persecution, and prolapsed vent. Other causes noted were hyperthermia (during summer), trauma, coccidiosis, ovarian neoplasia, being egg bound, urolithiasis, peritonitis (not egg yolk induced), leg fracture, caught in the structure, tumor (other than ovarian origin), wing fracture, exsanguination, and cardiomyopathy.

닭의 품종 간 스트레스 반응 정도 비교 분석

본 연구에서는 닭의 품종에 따른 개체의 스트레스 반응정도를 알아보고자 한국 재래닭과 단관 백색 레그혼종을 공시하고, 고밀도 사육에 따른 생리적 스트레스 표지 값을 비교 분석하였다. 스트레스 반응 정도는 혈액과 각 조직별 세포들에 대한 텔로미어 함량, DNA 손상율 및 열 스트레스 단백질(HSPs) 유전자의 발현율을 분석하고 비교하였다. 텔로미어 함량 및 감축율은 양적 형광 접합 보인법으로 분석하였고, DNA 손상율은 Comet assay로 분석하였다. 열 스트레스 단백질 유전자 발현율은 HSP70, HSP90-<TEX>${\alpha}$</TEX>, HSP90-<TEX>${\beta}$</TEX> 및 HMGCR을 표적으로 하여 real-time PCR로 분석하였다. 분석 결과, 한국 재래닭과 단관 백색 레그혼 간 품종에 따른 체중, 증체량, 텔로미어 감축율 및 DNA 손상율의 차이는 없는 것으로 나타났다. 그러나 고밀도 사육과 같은 스트레스 사양 관리는 품종에 상관없이 닭의 성장을 저해하고, 텔로미어 감축 및 DNA 손상을 촉진시키는 것으로 나타났다. 한편, HMGCR을 제외한 HSPs 유전자 발현율의 경우, 밀사 사육에 따른 요인뿐만 아니라, 품종 간에도 유의적 차이를 보였다. HSPs의 분석에 따른 스트레스 정도는 단관 백색 레그혼종이 한국 재래닭에 비해 보다 민감하게 반응하는 것으로 나타났다. 따라서 품종과 관계없이 닭에 있어 고밀도 사육이 강한 환경적 스트레스 요인임을 시사하고, 품종 간 스트레스의 반응 정도는 레그혼종이 한국 재래닭에 비해 다소 높은 것으로 사료된다. With Single Comb White Leghorn (WL) and Korean Native Chicken (KNC) breeds, we compared the stress response with chicken breeds that were subjected to a high stocking density. Stress response was analyzed by the quantity of telomeric DNA, the rate of DNA damage and the expression levels of heat shock proteins (HSPs) and hydroxyl-3-methyl-glutaryl coenzyme A reductase (HMGCR) genes on tissues and blood. The telomere length and telomere shortening rates were analyzed by quantitative fluorescence in situ hybridization on the nuclei of lymphocytes and tissues. The DNA damage rate of lymphocytes was quantified by the comet assay. The expression levels of HSP70, HSP90-<TEX>${\alpha}$</TEX>, HSP90-<TEX>${\beta}$</TEX> and HMGCR genes were measured by quantitative real-time polymerase chain reaction in lymphocytes. There was no significant difference between KNC and WL in body weight, weight gain, telomere shortening rate and DNA damage rate. However, the growth rate significantly decreased in chickens raised under high stocking density conditions, as compared to the control group. The telomere-shortening rate, DNA damage and HSPs expression of the lymphocytes were significantly higher in the high stocking density group than the control. The stress condition and breeds had a significant effect on the expressions of HSP70, HSP90-<TEX>${\alpha}$</TEX> and HSP90-<TEX>${\beta}$</TEX> in lymphocytes, except HMGCR. The stress response of WL was higher than that of KNC, as analyzed to the expression of HSP70 and HSP90-<TEX>${\alpha}$</TEX>. Therefore, we concluded that the chickens which were exposed to a high stocking density had increased the individual physiological stress response regardless of breeds, and White Leghorns are more susceptible to stress condition than Korean Native Chickens.

Identification of miRNAs associated with sexual maturity in chicken ovary by Illumina small RNA deep sequencing

BackgroundMicroRNAs have been suggested to play important roles in the regulation of gene expression in various biological processes. To investigate the function of miRNAs in chicken ovarian development and folliculogenesis, two small RNA libraries constructed from sexually mature (162-day old) and immature (42-day old) ovary tissues of Single Comb White Leghorn chicken were sequenced using Illumina small RNA deep sequencing.ResultsIn the present study, 14,545,100 and 14,774,864 clean reads were obtained from sexually mature (162-d) and sexually immature (42-d) ovaries, respectively. In total, 202 known miRNAs were identified, and 93 of them were found to be significantly differentially expressed: 42 miRNAs were up-regulated and 51 miRNAs were down-regulated in the mature ovary compared to the immature ovary. Among the up-regulated miRNAs, gga-miR-1a has the largest fold-change (6.405-fold), while gga-miR-375 has the largest fold-change (11.345-fold) among the down-regulated miRNAs. The three most abundant miRNAs in the chicken ovary are gga-miR-10a, gga-let-7 and gga-miR-21. Five differentially expressed miRNAs (gga-miR-1a, 21, 26a, 137 and 375) were validated by real-time quantitative RT-PCR (qRT-PCR). Furthermore, the expression patterns of the five miRNAs were analyzed in different developmental stages of chicken ovary and follicles of various sizes.ConclusionThe present study provides the first miRNA profile in sexually immature and mature chicken ovaries. Some miRNAs such as gga-miR-1a and gga-miR-21are expressed differentially in immature and mature chicken ovaries as well as among different sized follicles, suggesting an important role in the follicular growth or ovulation mechanism in the chicken.

Temporal myosin heavy chain isoform expression transitions faster in broiler chickens compared with Single Comb White Leghorns

Myosin heavy chain (MyHC), one of the major components in the contractile machinery of skeletal muscle fibers, is found in several isoforms during myogenesis. During chicken development, embryonic, neonatal, and adult MyHC isoforms are expressed. Broiler chickens have been selected for fast and large muscle growth, whereas Single Comb White Leghorn (SCWL) chickens have been selected for egg laying capabilities. This has led to an obvious difference in muscle growth and development with broilers being much larger than SCWL. The objective of this study was to determine if differences in muscle growth and development of SCWL and broilers are associated with differences in temporal expression of MyHC isoforms in skeletal muscle between the 2 breeds. Pectoralis major muscle (PM) was collected from SCWL and broilers at embryonic d 15, 17, and 19 and 1, 5, 11, 20, 27, and 33 d posthatch with n = 3 samples per time point and breed. Western blotting using 3 monoclonal antibodies (EB165, 2E9, and AB8) was performed to compare the expression patterns of embryonic/adult, neonatal, and adult isoforms of MyHC, respectively, for all time points in both SCWL and broiler chickens. Both broiler and SCWL chickens began expressing the neonatal MyHC isoform on d 5; however, SCWL chickens expressed the neonatal isoform much longer than broilers. The SCWL chickens had sustained expression of the neonatal MyHC isoform through d 27, whereas in broiler chickens the neonatal isoform was not expressed at d 20. Pectoralis major tissue from broiler chickens expressed the adult MyHC isoform as early as d 20, whereas the SCWL chickens began expressing the adult isoform later. The rate of transition to neonatal and adult MyHC isoforms in broilers and Leghorns is consistent with the faster maturation and growth of broilers relative to Leghorns. This relationship between faster growth of the PM and the rate of transition of MyHC isoforms within the fast skeletal muscle of the PM may indicate a selection marker for improvement of broiler PM growth.

In-Vitro and In-Vivo Binding Activity of Chicken Egg Yolk Immunoglobulin Y (IgY) against Gliadin in Food Matrix

Chicken egg yolk immunoglobulin Y (IgY) is a promising alternative for the prevention of enteric gliadin absorption, the predisposing factor of celiac disease (CD). IgY antibody was produced from the egg yolk of Single Comb White Leghorn chickens during the immunization period for the development of an oral immunotherapeutic agent. Here, we report the potential use of spray dried IgY antibody formulation using sugar protectants (mannitol, sorbitol, or microcrystalline cellulose powder (MCCP)). The long-term stability of the spray dried egg yolk powder formulated with 37.5% mannitol (EYP-M) preserved IgY antibody activity at 99.9%, which was significantly higher than that with other protectants (p < 0.05). In a dissolution test, the EYP-M shows 82.4% IgY activity after 2 h in simulated gastric fluid (SGF). A competitive ELISA at 50% inhibition (IC(50)) shows that 1.6 mg/mL EYP-M bound to 7.6 mg/mL and 10.5 mg/mL gliadin in SGF without and with food matrix conditions, respectively, whereas in simulated intestinal fluid, the formulation bound to 10 mg/mL gliadin, regardless of a food matrix. In-vivo study: BALB/c mice fed with EYP-M and gliadin at a ratio of 1:5 (w/w) demonstrated that gliadin absorption in the gastrointestinal tract was minimal at <1%. Thus, EYP-M containing IgY antibody may be used in CD patients to eliminate the effects of ingested toxic gliadin.

Telomeric DNA quantity, DNA damage, and heat shock protein gene expression as physiological stress markers in chickens

In this longitudinal study with Single Comb White Leghorn chickens, we investigated the effects of stress conditions in birds that were subjected to a high stocking density with feed restrictions on the quantity of telomeric DNA, the rate of DNA damage, and the expression levels of heat shock proteins (HSP) and hydroxyl-3-methyl-glutaryl coenzyme A reductase (HMGCR) genes. The telomere length and telomere-shortening rates were analyzed by quantitative fluorescence in situ hybridization on the nuclei of lymphocytes. The DNA damage rate of lymphocytes was quantified by the comet assay. The expression levels of HSP70, HSP90, and HMGCR genes were measured by quantitative real-time PCR in lymphocytes. The telomere-shortening rate of the lymphocytes was significantly higher in the stress group than in the control. The DNA damage also increased in birds raised under stress conditions, as compared with the control group. The stress conditions had a significant effect on the expressions of HMGCR and HSP90α in lymphocytes but had no significance on HSP70 and HSP90β in blood. We conclude that the telomere length, especially the telomere-shortening rates, the quantification of total DNA damage, and the expression levels of the HMGCR and HSP90α genes can be used as sensitive physiological stress markers in chickens.

Natural Infection and Transmission of a Retrovirus Closely Related to Myeloblastosis-Associated Virus Type 1 in Egg-Type Chickens

Myeloblastosis-associated virus type 1 (MAV-1) is an exogenous avian retrovirus with oncogenic potential. MAV-1 was detected in young chicks hatching from eggs produced by an experimental genetic line of egg-type chickens. Transmissibility of MAV-1 had not been documented previously. This investigation was intended to partially characterize the virus involved and to study its transmissibility and oncogenicity in naturally and contact-infected chickens. Commercially produced white and brown layer pullets free of exogenous avian leukosis viruses were commingled at hatch with naturally MAV-1-infected chickens. The original MAV-1-infected chickens were discarded after approximately 8 wk, and the contact-exposed chickens were maintained in isolation for 36 wk. Young specific-pathogen-free (SPF) single comb white leghorn chickens were added to the group to study possible horizontal transmission of MAV-1 in young chickens. Upon weekly virus isolation attempts, MAV-1 was readily isolated from the contact-exposed white layers but not from the brown layers between 36 and 53 wk of age (18 wk in total). Three-week-old SPF chickens were readily infected with MAV-1 by contact as early as 1 wk postexposure. Throughout 22 hatches derived from the white and brown MAV-1-contact-exposed layers (between 36 and 53 wk of age), MAV-1 was frequently detected in the white layer progeny, whereas the virus was seldom isolated from the progeny produced by the brown layers during the same 18-wk period. MAV-1 induced a persistent infection in some of the SPF chickens that were exposed by contact at 3 wk of age. Gross tumors were not detected in any of the originally infected experimental chickens at 8 wk of age, in the contact-exposed brown or white layers at the termination of the study at 53 wks of age, or in the contact-exposed SPF chickens at the end of the study at 12 wk of age. Exogenous avian leukosis-related viruses may still be detected in egg-type chickens, emphasizing the importance of thorough screening before incorporation of experimental genetic material into commercial genetic lines of egg-type chickens.

Effects of caponization and different forms of exogenous androgen implantation on immunity in male chicks

This study determined the caponization effects on the immune responses in male chicks. Different forms of exogenous androgen implantation on male chick immunity were compared. Healthy, uniform male Single Comb White Leghorn chicks were caponized at 3 wk of age. Birds were housed in individual cages (35 x 30 x 40 cm, length x width x height). Each of 27 sham-operated (sham) and caponized (capon) male chickens were used for trial 1. Trial 2 used 60 capons divided into 4 treatments with implants of either 1 mm i.d. x 3 mm o.d. 58 mg of cholesterol, testosterone (TES), 5alpha-dihydrotestosterone (5alpha-DHT), or 19-nortestosterone (19-NorT). The exogenous androgen was implanted immediately after caponization and resupplied every 4 wk for an entire 13-wk feeding trial. The results from trial 1 showed that the relative bursa weight increased compared with the sham treatment (P < 0.05). The 2 wk post-Newcastle disease virus titer and the delayed-type hypersensitivity (DTH) of 48 h post-phytohemagglutinin phosphate (PHA-P) injection were increased compared with the sham treatment (P < 0.05). In trial 2, implanted 5alpha-DHT and 19-NorT could decrease the relative bursa weight in capons (P < 0.05). The 2 wk post-Newcastle disease virus titer in the 5alpha-DHT group was higher than that in the cholesterol group (P < 0.05). The 19-NorT group had the highest (P < 0.05) PHA-P response. Peripheral blood lymphocyte subset population analysis revealed that the percentage of CD4 T cells in the TES group was lower (P < 0.05) compared with that of the 5alpha-DHT group. Differently, the percentage of CD8 T cells in the TES and 19-NorT groups was higher (P < 0.05) than that in the 5alpha-DHT group. Male chicks that were caponized had increased bursa weight and PHA-P response, whereas different forms of exogenous androgen implantation reverted the phenomena in an order of potency of 5alpha-DHT and 19-NorT > TES, and the PHA-P response was TES > 5alpha-DHT >19-NorT.

Effect of caponization and exogenous androgen implantation on muscle characteristics of male chickens

This study examined the effects of caponization and different exogenous androgen implantations on the growth performance and muscle characteristics of caponized male chickens. Male Single Comb White Leghorn chickens were caponized at 12 wk of age and selected at 16 wk of age for a 10-wk feeding period. Sixteen intact males and caponized (capon) chickens each were assigned for trial 1. Sixteen sham-operated male chickens (sham) and 64 capons were selected for trial 2, in which capons were randomly divided into cholesterol (CHOL), testosterone (TES), 5alpha-dihydrotestosterone (5alpha-DHT), or 19-nortestosterone (19-NorT) implantation at 16, 20, and 24 wk of age, with feeding to 26 wk of age. The result from trial 1 showed that caponization improved BW gain and feed conversion rate (P < 0.05) and decreased the comb length, height, and weight (P < 0.05). Breast muscle weight and gastrointestinal tract weight were higher in capons compared with intact males (P < 0.05). In trial 2, CHOL implantation decreased relative thigh muscle weight compared with the sham (P < 0.05), and only 19-NorT implantation increased relative thigh muscle weight to the compatible level with the sham (P > 0.05). 19-Nortestosterone and 5alpha-DHT implantations showed lower crude fat in the pectoral major muscle than CHOL (P < 0.05) and reached a compatible level with the sham (P > 0.05). All androgen implantation groups showed higher myofibrillar ATPase activity than CHOL (P < 0.05), and 19-NorT and 5alpha-DHT had the highest level (P < 0.05). Only 19-NorT implantation demonstrated higher shear value than CHOL (P < 0.05) to the compatible level with the sham (P > 0.05). Androgen implantation increased emulsifying capacity compared with CHOL (P < 0.05) and reached a compatible level with the sham (P > 0.05). Caponization decreased the blood TES concentration in male chickens, leading to changes in growth performance and muscle characteristics. After different androgen implantations in capons, 19-NorT showed the most effective results in increasing muscle quality and quantity, followed by the 5alpha-DHT and TES.

Reduction of Salmonella enterica var. Enteritidis colonization and invasion by Bacillus cereus var. toyoi inclusion in poultry feeds

The effect of continuously feeding the probiotic microorganism Toyocerin to birds inoculated with Salmonella Enteritidis field-isolated strains on Salmonella Enteritidis prevalence, and performance variables were studied in 2 experiments. The experiments were performed with 1) broiler chickens in floor pens until slaughter 42 d of age, challenge was performed on d 3, 7, or 14 with 2 x 10(6) cfu per chick, and 2) Single Comb White Leghorn chickens in cages until 28 d of age, challenge was performed on d 7 with 10(8) cfu per chick. The inclusion of Toyocerin in feed of inoculated broiler chickens did significantly (P < 0.05) improve ADG (by 3.4 g), BW (by 141 g), and feed conversion ratio (by -0.060 kg/kg) at the end of the trial at 42 d compared with inoculated and untreated birds. At the end of the trial at 42 d, the slaughter age, 42% of untreated birds were still positive for Salmonella, whereas Salmonella was not detected in Toyocerin-treated birds. In Leghorn chickens, at 3 wk after inoculation (the end of the trial), only 38% of birds from the Toyocerin-treated groups were Salmonella-positive, whereas 63% of birds were still Salmonella-positive in the untreated control treatment. No significant differences were detected in performance variables in Leghorn chickens. The results of the present experiments indicate that feeding Toyocerin reduced the prevalence of Salmonella in poultry and in the case of broiler chickens also significantly improved performance variables at slaughter age.

Production Performance of Single Comb White Leghorn Chickens Fed Growing Diets Containing Blood Meal and Supplemental Isoleucine

Laying performance of Single Comb White Leghorn (SCWL) chicks fed diets containing blood meal supplemented with isoleucine from hatch to ten weeks of age (WOA) was evaluated. In 4 replicates, 480 SCWL chicks were fed corn-based diets whose protein sources were 100% soybean meal (control), 100% blood meal (BM), 50% soybean meal+50% blood meal (SMBM), and 50% alfalfa meal+50% blood meal (AMBM). These diets contained 2,900kcal metabolizable energy (ME) per kg and 20% crude protein (CP). Blood meal comprised 16.8, 11.0 and 14.3% of the dietary composition in BM, SMBM, and AMBM diets, respectively. At 11-14, 15-18 and 19-46WOA birds in all treatment groups were fed corn-soy based diets containing 3,000, 3,080 and 2,900kcal ME/kg and 17.5, 16.5, and 17% CP, respectively. The birds were provided a 23, 8, and 16 hr light regimen at 0-10, 11-14, and 15-46WOA, respectively. Feed and water were provided at free choice and mortality was recorded as it occurred. At first egg, birds were observed for age, body weight and egg weight. Thereafter hen-day egg production, egg weight, egg mass, egg grade, internal egg quality and egg shell thickness were measured over five 28-day laying periods. Birds fed BM diets had 6.08, 5.24 and 2.63% higher (P<0.05) hen-day egg production than those fed the control, AMBM, and SMBM diets, respectively. Mean egg mass of BM fed birds was 5.65, 5.49 and 2.34% higher than that of the control, AMBM, and SMBM birds, respectively. Therefore, feeding diets containing blood meal and supplemented with isoleucine to SCWL chicks at 0-10WOA significantly improved their subsequent egg production performance, but depressed their internal egg quality and egg shell thickness.

Direct Enhancement of the Phagocytic and Bactericidal Capability of Abdominal Macrophage of Chicks by β-1,3–1,6-Glucan

Salmonella enterica serovar Enteritidis is the major zoonotic and intracellular pathogen. Different strategies have been developed to prevent the S. Enteritidis infection. The β-1,3–1,6-glucan of Schizophyllum commune was used as an immunological booster to determine the minimal dietary level of β-glucan that would restrict S. Enteritidis infection through the effects of β-glucan on the activity of macrophages and direct physical protection of the intestine. One-day-old male Single Comb White Leghorn chicks were used in all trials. In trials 1 and 2, the 0.1% β-1,3–1,6-glucan treatment completely eliminated the viable S. Enteritidis from spleen and liver in an oral challenge of 108S. Enteritidis without any harmful effect on BW, serum proteins, and immunoglobulin. Instead of a 21-d feeding period of β-glucan, a 14-d treatment was enough to eliminate the S. Enteritidis in spleen and liver. In trial 3, an increase in the relative weight of bursa of Fabricius and phytohemagglutinin-P-inducing cutaneous basophil hypersensitivity was observed (P < 0.05). In trials 2, 3, and 4, the direct or indirect effect of β-1,3–1,6-glucan on abdominal macrophages was examined. Sterilized 3% Sephadex G-50 was injected to induce abdominal (peritoneal) phagocytes in chicks fed with or without 0.1% β-1,3–1,6-glucan. Significantly increased phagocytic and bactericidal capability to S. Enteritidis was found in abdominal macrophages either pretreated or in vitro treated with 0.1% β-1,3–1,6-glucan. In conclusion, in addition to the physical properties to block S. Enteritidis entrance, 0.1% dietary β-1,3–1,6-glucan may enhance the host defense to S. Enteritidis by directly upregulating the phagocytosis and bactericidal activity of abdominal macrophages in chicks.

Growth Performance of Single Comb White Leghorn Chicks Fed Diets Containing Blood Meal Supplemented with Isoleucine

The suitability of blood meal supplemented with isoleucine as protein source for Single Comb White Leghorn (SCWL) chicks was evaluated. In four replicates, four hundred and eighty SCWL chicks were fed diets containing blood meal with supplemental isoleucine from day-old to 10 weeks of age (WOA). The experimental diets were corn-based with the protein sources being 100% soybean meal (control), 100% blood meal (BM), 50% soybean meal+50% blood meal (SMBM), and 50% alfalfa meal+50% blood meal (AMBM). Blood meal comprised 16.8%, 11.0% and 14.3% of the total ration in BM, SMBM, and AMBM diets, respectively. Experimental birds were provided a 23 hr light regimen and feed and water were provided at free choice. Feed consumption (FC) and body weights (BW), from which feed conversion ratios (FCR) and body weight gains (BWG) were calculated, were measured weekly. Shank lengths (SL) were measured weekly and mortality was recorded as it occurred. Birds fed the BM diet exhibited significantly lower (P SMBM>AMBM>Control. Based on this study, substitution of up to 50 percent of soybean meal with blood meal supplemented with isoleucine in corn-soy based diets did not adversely affect growth performance of SCWL chicks from day-old to 10 WOA.

The Effects of Caponization Age on Muscle Characteristics in Male Chicken

This study examined the caponization effects on the muscle characteristics (quality and quantity) of caponized male chickens fed before or after sexual maturity. Healthy and uniform Single Comb White Leghorn chickens were caponized at 3-week-old. Feeding was conducted until 16-week-old in trial 1 or from 12-week-old to 26-week-old in trial 2. Ten sham operated male chickens (Sham) were also assigned to each trial as the control group. Chickens used in both trials were housed in individual cages with each chicken representing one replicate. The results showed that early caponization (3-week-old) significantly increased (p<0.05) body weight and pectoral major muscle weight and percentage at 16-week-old compared to the Sham in trial 1. Caponization significantly increased (p<0.05) the protein content of the pectoral major muscle, but decreased (p<0.05) the ash content. Late caponization (12-week-old) significantly decreased (p<0.05) the ash content, myofibrillar ATPase activity and emulsification capacity of the pectoral major muscle in mature capons (26-week-old) compared to the Sham in trial 2. Early caponization (3-week-old) only increased the weight and protein content of the pectoral major muscle with decreased ash content in 16-week-old capons. Late caponization (12-week-old) showed no affects on pectoral major muscle quantity, while it decreased the ATPase activity and enhanced the emulsification capacity in mature (26-week-old) capons. Hence, the muscle quality improvement was shown as capons were fed to sexual maturity.

Effect of Caponization and Testosterone Implantation on Hepatic Lipids and Lipogenic Enzymes in Male Chickens

This study was conducted to determine the role and effects of testosterone in lipogenesis by measuring and analyzing the lipid composition and lipogenic enzyme activity of livers from capons treated with various doses of exogenous testosterone implant. Healthy and uniform male Single Comb White Leghorn chickens were caponized at 12 wk of age. Sixteen-week-old capons were randomly selected for a 10-wk experiment. Fifteen intact males and 15 capons were used for trial 1. In trial 2, 10 sham-operated males and 40 capons were used. The capons were randomly divided into 4 independent treatments with sialistic implants of cholesterol (1.62 mm i.d., 3.6 mm o.d., 9.24 +/- 0.36 mg; CHOL), low testosterone (1 mm i.d., 3 mm o.d., 5.88 +/- 0.23 mg), medium testosterone (1.62 mm i.d., 3.16 mm o.d., 9.81 +/- 0.17 mg), or high testosterone (2 mm i.d., 4 mm o.d., 16.7 +/- 0.24 mg). In trial 1, the results showed that caponization increased total hepatic lipid and triacylglycerol contents and decreased the nonesterified fatty acid content (P < 0.05) compared with the intact male. Meanwhile, caponization increased nicotinamide adenine dinucleotide phosphate -malic dehydrogenase (MDH) activity and MDH mRNA content (P = 0.09) simultaneously. In trial 2, comparing treatments with the various implantation doses of testosterone, the liver triacylglycerol content of capons the medium-dose implantation was decreased as compared with those receiving CHOL (P < 0.05). The total lipid and phospholipid contents of liver were decreased in capons receiving the high-dose implantation (P < 0.05), whereas the relative weight and nonesterified fatty acid content were increased (P < 0.05) and reached the same level as those in the sham treatment (P > 0.05). With an increased implantation dose, MDH activity of capons receiving the medium dose or higher was not different from those receiving the CHOL and sham treatments (P > 0.05). The increase in MDH activity at the transcriptional and translational levels suggests that caponization may positively regulate hepatic lipogenesis. In contract, implantation of testosterone up to the threshold concentration depressed hepatic lipogensis and lipid accumulation.

The Effects of Fumonisin B1 on viability and mitogenic response of avian immune cells

Fumonisin B1 (FB1) is a mycotoxin produced by the fungus Fusarium verticillioides (formerly Fusarium moniliforme) and is found in diverse crops such as corn, wheat, and barley. Many diseases linked to FB1, such as porcine pulmonary edema, rat hepatic cancer, and equine leukoencephalomalacia, indicate a compromised immune system. The purpose of this study was to determine whether FB1 altered immunological responses in various cell populations of Single Comb White Leghorn chicks. Cells collected for this study were obtained from those immunological organs with well-defined responses (i.e., spleen, thymus, and blood). Cell populations were exposed to 5 to 50 µg/mL FB1 in vitro for 24 to 72 h, and viability and mitogenic response were evaluated. The effects of FB1 on the mitogenic response were evaluated in cell populations from the spleen and blood stimulated with the mitogens, lipopolysaccharide, concanavalin A, and pokeweed mitogen and in thymocytes stimulated with concanavalin A. The 3-(4,5-dimethylthazol-2-yl)-diphenyl-2H-tetrazolium bromide (MTT) reduction assay was used to assess viability and mitogenic response. Fumonisin B1 decreased spleen cell viability and mitogenic response, albeit the degree of decrease varied with mitogen and time of exposure. Fumonisin B1 increased number of viable thymic cells at 50 µg/mL but had no effect on the mitogenic response of thymocytes. Fumonisin B1 had no effect on blood lymphocyte viability or mitogenic response.

The effects of dietary vitamin E and selenium deficiencies on plasma thyroid and thymic hormone concentrations in the chicken

Beginning at hatching, male Cornell K strain single comb white leghorn chickens were fed a basal diet, with or without vitamin E (100 IU/kg) and/or selenium (Se, 0.2 ppm). After 3 weeks of treatment, animals fed either the Se-deficient or basal diet had significantly reduced plasma Se-dependent glutathione peroxidase activities when compared to those fed a vitamin E and Se-supplemented diet. Similarly, animals fed the vitamin E-deficient or basal diet had significantly reduced plasma α-tocopherol levels. The effect of these treatments on plasma concentrations of thyroid hormones (T 3/T 4), growth hormone (GH), and thymic hormone (thymulin) was determined using radioimmunoassay and ELISA. A deficiency in Se, but not in vitamin E, resulted in an increase in plasma T 4 concentrations while plasma T 3 concentrations were decreased. Plasma GH levels showed some fluctuation as a result of the dietary treatments but there was no significant correlation between plasma GH levels and any of the other variables. A significant decrease in plasma thymulin levels was observed in Se-deficient birds compared to those receiving adequate Se in the diet. A vitamin E deficiency had no measurable effect on plasma thymulin levels. From these studies, we conclude that plasma thymulin concentrations directly correlate with plasma T 3 concentrations which are negatively affected by a Se deficiency.

Immunogenicity of ad libitum drinking water administration of bovine serum albumin in Leghorn chickens

Oral administration of protein antigen in solution routinely leads to development of oral tolerance in most mammals but has been reported to be fully immunogenic in chickens. Previous studies, including several performed by our laboratory, have demonstrated that oral administration of discrete amounts of BSA for 6 consecutive days is fully immunogenic. This study was performed to determine immunoresponsiveness to protein antigen administered ad libitum at low levels in drinking water compared with i.p. and oral gavage routes of administration. Seven days following the last oral immunization, serum was assayed for IgG, bile for IgA, and tissue culture supernatant from 3 distinct lower intestinal regions for IgG and IgA in immunized and nonimmunized single-comb White Leghorn chickens. Systemic responses in the serum of experimental birds revealed a greater (P < 0.001) IgG response when BSA was administered via i.p. injection or by drinking water compared with gavage administration or nonimmunized controls. Responses measured in bile revealed that BSA administration in the drinking water resulted in a greater (P < 0.001) secretory IgA response compared with i.p. or gavage administration, and negative control groups. Intestinal antigen specific IgG, but not IgA, was elevated (P < 0.05) in all intestinal areas tested in birds immunized against BSA by drinking water and i.p. routes of administration, compared with other experimental groups. Taken together, the present experiments demonstrate that ad libitum drinking water administration of a protein antigen is as effective as i.p. administration or gavage routes of antigen exposure and potentially describe a novel approach to immunization of commercial poultry with purified protein antigens.

Shell Characteristics of Eggs from Historic Strains of Single Comb White Leghorn Chickens and the Relationship of Egg Shape to Shell Strength

The effect of long term genetic selection on shell characteristics was determined by analyzing eggs acquired from Agriculture Canada: Ottawa Control Strain 5, from a 1950 base population; 7, from a 1959 population; and 10, from a 1972 population. H&N Nick Chick 1993 commercial strain was also included because it shares genetic ancestry with the three historic strains. Eggs were collected beginning at 28 wk of age, then every 4 wk through the end of the study at 86 wk of the laying cycle and egg weight, egg height, egg width, shell weight, shell thickness, egg specific gravity, and shell breaking force measured. The relationship of egg shape and weight as factors affecting shell strength were also investigated. Significant differences (P < 0.05) were found between strains for egg shape and a progressive increase in weight and surface area of eggs from the 1950 strain to the current strain. The shape index indicates that the current strain has increased egg size with the greatest increase seen in egg width. The mean breaking force of eggs from the current strain was higher (P< 0.05) than the other strain's eggs with no strain differences in percent shell weight, shell thickness, or specific gravity. A decline in breaking force, percent shell weight, and specific gravity was observed among all the strains over the production period. The results from this study suggest that genetic selection has produced larger eggs that are rounder in shape.

Maternal Carotenoid Status Modifies the Incorporation of Dietary Carotenoids into Immune Tissues of Growing Chickens (Gallus gallus domesticus)

Carotenoids provide pigmentation to avian species, and also have immunomodulatory potential, although experimental results are often inconsistent. Therefore, dietary carotenoid deposition into immune tissue of growing chicks was examined in relation to their maternal carotenoid status (i.e., yolk carotenoid level). Single-comb white leghorn chicks were hatched from carotenoid-replete (C+) or carotenoid-deplete (C-) eggs. For 4 wk posthatch, chicks were fed diets whose carotenoid level ranged from 0 to 38 mg total carotenoid/kg. Carotenoid additions consisted of lutein + canthaxanthin at a ratio of 4:1. After 4 wk, the carotenoid concentration of thymus, bursa, liver, plasma and shank epithelium was measured by HPLC. Egg yolk-derived carotenoids were detectable in chicks fed 0 dietary carotenoids for 4 wk. Chicks hatched from C+ eggs had significantly greater tissue lutein, zeaxanthin and/or canthaxanthin for all tissues (P < 0.05), compared to chicks hatched from C- eggs. Only bursa carotenoids were not dependent on chick diet (P = 0.24); for all other tissues, C+ chicks incorporated dietary carotenoids in a dose-dependent manner (P < 0.01), whereas C- chicks never achieved the same level of carotenoid incorporation. This study demonstrated the importance of maternal carotenoid status on incorporation of yolk- and diet-derived tissue carotenoids in an avian model, and may explain some variability in carotenoid-based research, given that maternal carotenoid status is rarely controlled.