Adaptation of the White Fulani cattle to the tropical environment.

This review summarizes the available information on the adaptation and the performance of White Fulani cattle in tropical environments. White Fulani cattle is an indigenous breed of cattle widely distributed in the humid tropical regions of Africa and plays significant roles in meat and milk production, as well as draught purposes. Poor management and the harsh environmental conditions in the tropics encumber the optimal productive and reproductive performance of the breed, having about 4.75 years age at first calving, 57% calving rate, 18 months calving interval and 3 to 4 calves are born in a reproductive lifetime. The cattle breed adapts to these climatic patterns via physiological, morphological, behavioral, genetic, and metabolic responses. Different physiological mechanisms and morphological features such as their white coat color, hair coat thickness, and lengthy rump appear to play an important adaptive role. The distinct genetic traits (including the possession of seven genetic variants of HSP 90 gene) of the breed afford them some levels of thermotolerance and high resistivity to some endemic diseases (such as trypanosomiasis, liver fluke, brucellosis and foot and mouth disease) in the tropics constitute inherent characteristics that should be explored in detail using molecular assisted approaches. The productive performance of the breed under different systems is discussed. A better understanding of the adaptive characteristics of White Fulani cattle could provide crucial information on the best management approach/techniques that should be adopted to improve the performance, productivity, and sustainability of this cattle breed. Therefore, this review aims to compile the various production, reproduction and adaptation traits of the breed and presents vital information underlying their thriving and survivability in tropical environments.

Effects of pre-incubation storage duration and nonventilation incubation procedure on embryonic physiology and post-hatch chick performance.

This study investigated the effects and possible interactions of storage and nonventilation during incubation for eggs from Sasso broiler breeder flock on pre- and post-hatch incubation results. A total of 1,260 Sasso eggs from a 58-wk-old broiler breeder flock were individually numbered, weighed and stored for 7 d or for 18 d in a climate-controlled room (16°C, 75% RH). After storage, eggs were weighed, and randomly assigned equally into 2 incubators. One of the incubators was ventilated (V) for the entire incubation and the second was nonventilated (NV) for the first 12 d. At d 18, the eggs were weighed, candled, and fertile eggs were transferred from the turning trays to hatching baskets. During the last 3 d of incubation, hatching eggs were checked individually every 3 h for hatching events and hatchability of fertile eggs. After pull out at d 21.5, post-hatch performances was determined until 1 wk of age. Results showed that, embryo weights from eggs in NV incubator was significantly higher (P < 0.05) in both stored eggs compared to those from eggs in ventilated incubator, but embryos from eggs stored for 18 d were smaller (P < 0.05) than those from eggs stored for 7 d. Hatchability was higher (P < 0.0001) in NV incubator compared to V incubator in both 7 d and 18 d stored eggs and an interaction was found between incubation ventilation and storage duration on both hatchability and embryonic mortality (P < 0.0001). Chick weights from NV incubator at 7 d post-hatch was greater (P = 0.0009) than those from V incubator. Serum Tri-iodothyronine (T3) and Thyroxin (T4) concentrations were significantly higher (P < 0.05) in NV compare to V group. It was concluded that the effect of long-term pre-incubation storage on embryonic physiology and post-hatch growth interacted significantly with incubation ventilation and that nonventilation can compensate for the negative effects of storage on some hatching and post-hatch performances.

Effects of egg storage duration on egg quality, metabolic rate, hematological parameters during embryonic and post-hatch development of guinea fowl broilers.

Considering the value of guinea fowl keets, successful incubation of eggs is particularly desirable in this poultry species. This study evaluated the effect of egg storage duration on egg quality, heat production, hematological parameters during embryonic development and post hatch performance of guinea fowl broilers. A total of 800 hatching eggs of guinea fowl were used for this study. Before incubation, 12 eggs per treatment were used to analyse egg quality. Then, eggs were numbered, weighed, and assigned to 2 treatment groups of 400 eggs each according to storage duration of 5, and 10 d at a temperature of 18°C. The eggs were set for incubation at 37.7°C and 55% relative humidity for 28 d in a forced-draft incubator. To determine heat production as a measure of metabolism, 60 eggs in each replicate were transferred to respiratory cages post hatch two 12 wk old guinea fowl were also used to determine heat production. CO2 and O2 were recorded to calculate heat production at internal pipping, hatch and at 12 wk of age. The hatched keets were reared for 12 wk and data were collected on feed intake, body weight and feed conversion ratio. Blood samples were collected at hatch and at 12 wk of age from 24 guinea fowls per treatment to analyze haematological parameters. The results showed that embryos and guinea fowls at 12 wks of age from eggs stored for 5 d had higher (P ˂ 0.05) heat production and body weights. However, a significant higher (P ˂ 0.05) level of basophile, eosinophils, and lymphocytes was observed in guinea fowls from 10 d storage egg. It was concluded that extended duration of egg storage negatively influenced the metabolic rate of embryos. It also impacted hematological parameters which may suggest influence on immune response during embryonic and post-hatch growth.

Environmental stress and livestock productivity in hot-humid tropics: Alleviation and future perspectives.

Tropical environments are characterized by persistently high temperature and relative humidity and the harsh environmental conditions pose a serious limitation on the optimal performance of the animals raised in this region. Heat stress causes deleterious effects on welfare, immunology and physiology of farm animals with a resultant impact on their productivity as the use of body resources is re-organized and the metabolic priorities of animals shift away from production, growth, health and reproduction. It is imperative to understand the mechanisms involved in the thermoregulation of animals under tropical conditions in order to develop appropriate strategies for their improvement. This review focuses on the available data on the increasing global temperature and the adverse impact of tropical conditions on animals' adaptive mechanism affected during thermal stress on production performance, intestinal and ileal microbiome, physiological responses, antioxidant system, metabolic responses, cellular and molecular response, adaptive mechanism strategies to heat stress and also strategies to palliate environmental stress on livestock under humid tropical conditions including environmental manipulation, genetic opportunity, epigenetic and feeding modification. Overall, the present review has identified the disturbance in the physiological indices of tropical livestock and the need for concerted efforts in ameliorating the adverse impacts of high ambient temperature aggravated by high humidity on livestock in tropical environments. Further research is needed on genotype-by-environment interaction on the thermotolerance of different livestock species in the tropics.

Early age thermal manipulation on the performance and physiological response of broiler chickens under hot humid tropical climate.

Initial brooding temperature is critical for post-hatch growth of broiler chickens. A study was conducted to investigate the early age thermal manipulation (EATM) on the performance and physiological responses broiler chickens under hot humid tropical climate. A total of 260 unsexed day-old Arbor-acre broiler chicks were assigned to five thermal treatments of brooding temperature regimens having 4 replicates of thirteen birds each. The heat treatments were: initial brooding temperature of 35 °C for the first 2 days, and then decreased subsequently, gradually to 22 °C at 21 d of age (CT), initial temperature of 35 °C, sustained for the first 4 days and then decreased gradually (conventionally) (FD), initial temperature of 35 °C for the first 7 days (SD), the birds in CT, but the brooding temperature was raised to 35 °C again for another 3 days from day 7 (SD3), initial brooding temperature of 35 °C for the first 10 days (TD). Data were collected on daily feed intake and weekly body weights. Blood samples were collected from 8 birds per treatment weekly for the determination of plasma uric acid, triglycerides, triiodothyronine (T3) and creatinine kinase. Data obtained were laid out in a Completely Randomized Design (CRD). Results showed that the final weights of the birds in FD were higher (P < 0.05) than those of the other treatments at the finisher phase. Feed intake of the birds in FD was higher than those of SD3 and TD. FCR of broiler chickens in CT, SD, SD3 and TD was higher than that of FD. The rectal temperature, plasma MDA and blood glucose of the thermally challenged birds in FD was generally better (P < 0.05) than those of the other treatments. It was concluded that EATM can be used to improve performance and also protect broiler chickens from acute heat stress at market age.

Reproductive performance of layer chickens reared on deep litter system with or without access to grass or legume pasture.

Despite several studies carried out to investigate the effects of access to pasture on poultry performance, there is a dearth of information on the comparative benefit of grass and legumes. This study investigated the effects of rearing systems [deep litter system (DL), deep litter with access to legumes (LP) or grass (GP) pastures] on the performance of ISA Brown layers. Two hundred and forty 12-week-old pullets were housed for this study. They were reared until 60 weeks of age. Eighty birds were assigned to each treatment; each treatment had four replicates of 20 birds each. Two birds per replicate were slaughtered at weeks 20, 35 and 58 for determination of the weights of liver, ovary, oviduct and the number of follicles. Daily egg production records were kept from the day of first egg to 42 weeks in lay. Body weights were recorded weekly. Results indicated that at 20 weeks of age, the hens kept in the LP had higher (p < 0.05) ovary weight (g) (34.98 ± 1.4), oviduct weight (52.55 ± 2.28) and oviduct length (cm) (49.73 ± 11.34), and higher number of large yellow follicles (3.75 ± 1.31) and small yellow follicles (12.75 ± 5.17) than those in the GP (0.83 ± 0.02, 1.68 ± 0.19, 16.38 ± 1.14, 0.00 and 0.00), and DL (1.03 ± 0.11, 1.48 ± 0.48, 14.43 ± 0.58, 0.00 and 0.00) respectively. The age (days) at first oviposition was earlier (p < 0.05) in the LP (139.25 ± 0.85) than that in the GP (146.75 ± 0.48) and DL (146.75 ± 0.48). The hen-day egg production was lower (p < 0.05) in GP (74.19 ± 1.25) than that in the DL (78.82 ± 0.78) and LP (79.93 ± 1.13) at mid-laying phase. Concentrate feed intake was lower (p < 0.05) in LP and GP than DL suggesting economic benefit. It was concluded that access to LP enhanced the performance of layers than DL and GP as indicated by the parameters measured.

Cardiovascular risk factors and metabolic syndrome in people with established psychotic illnesses: baseline data from the IMPaCT RCT study--Corrigendum.

The author regrets to announce that affiliation 8, in the above article (Gardner-Sood et al. 2015), contained an error in the author affiliation address and author surname, which were published in the approved article. The correct surname and affiliation address are given below. J. Eberhard, Clinical Psychiatric Research Center, Lund University, Skåne, Sweden

Cardiovascular risk factors and metabolic syndrome in people with established psychotic illnesses: baseline data from the IMPaCT randomized controlled trial.

BACKGROUND: The aims of the study were to determine the prevalence of cardiometabolic risk factors and establish the proportion of people with psychosis meeting criteria for the metabolic syndrome (MetS). The study also aimed to identify the key lifestyle behaviours associated with increased risk of the MetS and to investigate whether the MetS is associated with illness severity and degree of functional impairment. METHOD: Baseline data were collected as part of a large randomized controlled trial (IMPaCT RCT). The study took place within community mental health teams in five Mental Health NHS Trusts in urban and rural locations across England. A total of 450 randomly selected out-patients, aged 18-65 years, with an established psychotic illness were recruited. We ascertained the prevalence rates of cardiometabolic risk factors, illness severity and functional impairment and calculated rates of the MetS, using International Diabetes Federation (IDF) and National Cholesterol Education Program Third Adult Treatment Panel criteria. RESULTS: High rates of cardiometabolic risk factors were found. Nearly all women and most men had waist circumference exceeding the IDF threshold for central obesity. Half the sample was obese (body mass index ≥ 30 kg/m2) and a fifth met the criteria for type 2 diabetes mellitus. Females were more likely to be obese than males (61% v. 42%, p < 0.001). Of the 308 patients with complete laboratory measures, 57% (n = 175) met the IDF criteria for the MetS. CONCLUSIONS: In the UK, the prevalence of cardiometabolic risk factors in individuals with psychotic illnesses is much higher than that observed in national general population studies as well as in most international studies of patients with psychosis.

An analysis of the ruminal bacterial microbiota in West African Dwarf sheep fed grass- and tree-based diets.

AIMS: To measure the impact of supplementing a forage diet with tree-based browse on the ruminal bacterial communities of Nigerian West African Dwarf (WAD) sheep. METHODS AND RESULTS: Fifteen WAD sheep were fed a control diet of forage (Panicum maximum), with 12 animals shifted in groups of three to one of four browse-supplemented diets (Albizia saman, Bridelia micrantha, Ficus sur, or Gmelina arborea). These browse plants were shown in a concurrent but separate study to be reasonably nutritious (based on chemical composition and fibre constituents) and nontoxic (based on tannin, phytate, saponin, alkaloid and oxalate levels). Rumen liquids and solids for DNA extraction were collected via intubation from two animals in each group before and after dietary shift. Bacterial 16S rRNA gene regions V6-V8 were sequenced by 454 pyrosequencing. All communities were highly diverse and dominated by the phyla Firmicutes, Bacteroidetes, Tenericutes, Actinobacteria and Proteobacteria. All communities shared members of the genera Butryivibrio, Prevotella and Ruminococcus. Our analysis defined a core sets of bacteria shared by all animals, forage-fed animals and browse-fed animals. Community structure shifted dramatically in animals fed A. saman or G. arborea. CONCLUSIONS: The impact of tree-based browse on the ruminal bacterial community of Nigerian WAD sheep varies by browse species, likely due to differences in browse composition. SIGNIFICANCE AND IMPACT OF THE STUDY: Our study describes the first neotropical small ruminant bacterial microbiome and supports diet supplementation with specific tree-based browse for WAD sheep.

Comparison of Cobb and Ross strains in embryo physiology and chick juvenile growth.

Broiler performance is known to be related to embryonic developmental parameters. However, strain or genotype differences with regard to embryo physiological parameters and juvenile growth have received little attention. A total of 1,200 hatching eggs produced by Cobb and Ross broiler breeders of the same age were studied. At setting for incubation and between 66 and 130 h of incubation, egg resonant frequency (RF) was measured as an indicator of embryonic development. Also, eggs were weighed before setting and at d 18. From d 10 to 18 of incubation, remaining albumen was weighed. During the last days of incubation, hatching events such as internal pipping (IP), external pipping, and hatch were monitored every 2 h. Hatched chicks were recorded and weighed. At IP stage, gas partial pressures in the egg air chamber were measured. Hatched chicks were reared for 7 d and weighed. Results indicate that RF of Ross eggs were lower than those of Cobb eggs (P < 0.01) and starting time point of RF decrease occurred earlier in Cobb eggs than in Ross eggs. Relative egg weight loss up to 18 d of incubation was lower in Cobb than in Ross (P < 0.05). At IP, partial pressure of CO(2) was higher in Cobb than in Ross (P < 0.05) with shorter incubation duration in Cobb. Between 6 and 60 h posthatch, heat production was higher in Cobb than in Ross (P < 0.05). At 7 d posthatch, Cobb chicks were heavier than Ross chicks (P < 0.05). It is concluded that Cobb and Ross embryos-chicks have different growth trajectories leading in different patterns of growth resulting from differences in physiological parameters.

Indirect effect of IGF2 intron3 g.3072G>A mutation on prolificacy in sows.

A QTL located in the paternally expressed insulin-like growth factor 2 (IGF2) gene is known to increase muscle growth and reduce fat deposition in pigs. This makes the QTL in IGF2 a good marker for use in pig breeding programmes. However, care has to be taken as it is postulated that increased leanness and lowered fat deposition may have a negative effect on the prolificacy and longevity of sows. Selection of sire and dam lines for different alleles of the mutation in the paternally imprinted IGF2 gene could actually provide a solution to this problem. Therefore, in this study, the effect of the IGF2 QTL on prolificacy-related traits in sows was investigated. It was found that the paternal IGF2 wild-type allele was associated with higher reproduction performance in the sow. Moreover, it was also examined whether the difference in prolificacy in sows could be a consequence of differential IGF2 expression in the ovarian follicles of the sow or whether it is mainly a secondary effect caused by differences in fatness traits. Therefore, IGF2 expression was measured in follicles of different sizes from sows with different genotypes for the paternal IGF2 allele. It was observed that, however, while the size of the follicles was associated with follicular IGF2 expression level, the IGF2 genotype was not. It could be concluded that the difference in prolificacy of sows with a different paternal IGF2 genotype could be a secondary effect, resulting from differences in fat deposition.

Evaluation of supplementary stevia (Stevia rebaudiana, bertoni) leaves and stevioside in broiler diets: effects on feed intake, nutrient metabolism, blood parameters and growth performance.

A perennial schrub, stevia, and its extracts are used as a natural sweetener and have been shown to possess antimicrobial properties. Stevia contains high levels of sweetening glycosides including stevioside which is thought to possess antimicrobial and antifungal properties. Little is known about the nutritional value of the schrub in livestock. This study determined the potential use of the shrub as a prebiotic animal feed supplement in light of the recent ban on the use of antibiotics in animal feed and the role of its constituent stevioside in the effects of the shrub. Male Cobb broiler chicks were fed a basal broiler diet without antibiotic but with performance enhancing enzyme mix (positive control), a basal diet without antibiotic and enzymes (negative control), or diets in which 2% of the negative control diet was replaced with either dried ground stevia leaves or 130 ppm pure stevioside during 2 week starter and 2 week grower periods. Body weight gains, feed conversion, abdominal fat deposition, plasma hormone and metabolites and caecal short chain fatty acids (SCFA) were measured in the broilers at 2 and 4 weeks of age. There was no significant effect of the treatments on feed intake during the starter period but birds fed diet supplemented with stevia leaves and stevioside consumed more feed (p < 0.05) than those fed the positive control diet during the grower period. Weight gain by birds fed the positive control and stevioside diets was higher (p < 0.05) than those fed other diets only during the starter period. Feed/gain ratio of birds fed the positive control and stevioside diets was superior (p < 0.05) to others. There was no effect of the treatments on nutrient retention and water content of the excreta. Dietary stevia leave and stevioside decreased total concentration of SCFA and changed their profile in the ceca. There was no effect of the treatments on pancreas weight. Dietary stevia reduced blood levels of glucose, triglycerides and triiodothyronine (T(3)) but had no effect on non-esterified fatty acids. In contrast, stevioside only decreased T(3). Both the stevia leaves and stevioside diets significantly increased abdominal fat content. It is concluded that dietary enzyme growth promoters are beneficial to the broilers only during the starter stage and that inclusion of stevia leaves or stevioside has no beneficial effect on the performance of broilers.

Effects of high CO2 level during early incubation and late incubation in ovo dexamethasone injection on perinatal embryonic parameters and post-hatch growth of broilers.

1. A total of 1200 Cobb broiler breeder eggs were incubated under either standard conditions (C group) or high CO(2) levels (CO(2) group) during the first 10 d of incubation. The CO(2) level of the CO(2) incubator was attained gradually by a natural build-up of CO(2) due to air-tight closure of the incubator. From d 10 of incubation onwards, all eggs were incubated under standard incubation conditions. At d 18 of incubation, the eggs of both incubation groups (CO(2) and C group) were either injected with water-soluble dexamethasone (DEXA group) or with saline (0.9% NaCl; saline group) or were not injected (control). 2. Body weights, plasma hormonal concentrations (T(3), T(4) and corticosteroid) and glucose concentrations were measured regularly during the perinatal (at IP, internal pipping) and post-hatch period (at 1, 2, 4 and 6 weeks post-hatch). Additionally, hatchability and pattern of embryonic mortality were determined after hatch. 3. The results showed that high CO(2) levels during the first 10 d of incubation or dexamethasone injection at d 18 of incubation decreased embryo mortality, mainly because of a reduction in embryo malpositioning. However, a combination of a CO(2) incubation and a dexamethasone injection led to an increase in embryo mortality and therefore a decrease in hatchability. 4. Although dexamethasone injection at embryonic d 18 decreased body weight in the second week of the rearing period and CO(2) incubation increased body weight during the first 2 weeks of the rearing period, no consistent effect of both the incubation and injection treatments on body weight at slaughter age was observed.

The effect of nonventilation during early incubation on the embryonic development of chicks of two commercial broiler strains differing in ascites susceptibility.

Despite thorough selection during the last decade, the incidence of ascites is still high in modern broiler strains. Although ascites occurs mostly at the end of the rearing period, there are indications that the etiology of this problem may have started during embryonic development. Recent studies have shown that the post-hatch performance of the broiler chick might be influenced by changing the environmental conditions in the incubator during embryonic development. This study investigated the effect of increasing incubator CO(2) concentration up to 0.7%, by nonventilation during the first 10 d of incubation, on the embryonic development of 2 commercial broiler strains (Cobb and SAS) differing in their susceptibility for ascites syndrome. The Cobb strain is suspected to be less susceptible than the SAS strain. Overall, the chick embryos of the Cobb strain had a faster development than those of the SAS strain as expressed by their higher BW from embryonic day (ED)10 until ED18. Nonventilation stimulated embryonic development resulting in higher embryonic BW, early hatch, and narrower spread of hatch in both strains. In the SAS strain, nonventilation improved hatchability by more than 10%. Gas composition of the air cell in the egg of the nonventilation groups (both Cobb and SAS) had higher partial pressure of CO(2) and lower partial pressure of O(2) from ED11 until ED14 compared with the ventilation groups. During the entire incubation period, partial pressure of CO(2) was higher in eggs of the Cobb strain compared with the SAS strain. Plasma triiodothyronine, thyroxine, and corticosterone levels were different at the end of the incubation period and during hatching due to nonventilation at the beginning of incubation. It is concluded that nonventilation during the first 10 d of incubation had a stimulatory effect on embryonic development of the 2 broiler strains with no effect of heart weights but with effects on hormone levels, air cell pressures, and hatching parameters.

Acid-base balance in chicken embryos (Gallus domesticus) incubated under high CO2 concentrations during the first 10 days of incubation.

Recent studies show the importance of differential CO2 levels during the first half of incubation of chicken eggs on embryonic and postnatal growth. However, it is not known how external higher CO2 levels affect embryonic acid-base balance. In this study, the effect of an early rise in CO2, between 25th and 96th hour of incubation to 1.5% and maintained at that level until 240 h of incubation, was investigated on air cell gases, blood gas parameters from ED10 onwards and on embryonic growth and hatching parameters. Higher external CO2 concentrations resulted in a faster acidification of albumen resulting in a faster decrease of albumen pH with development, illustrating the capacity of albumen to cope with higher environmental CO2. Moreover, PCO2 in blood was higher in CO2 incubated embryos at embryonic day 10 and 11 but without a change in blood pH. The additional increase in plasma HCO3- concentration at day 10 and 11 was responsible for buffering the higher PCO2 in CO2 incubated embryos in order to stabilize pH. However, effects of hypercapnia on blood acid-base parameters extinguished 2 days after termination of high CO2 incubation. Embryonic growth was modestly accelerated which was reflected in higher embryonic weights at day 6 and 10 and a significant earlier hatching; hatchling weights were not different between treatment groups.

Non-ventilation during early incubation in combination with dexamethasone administration during late incubation: 1. Effects on physiological hormone levels, incubation duration and hatching events.

This study investigated the effect of non-ventilation of the incubator during the first 10 days of incubation and its combination with dexamethasone administration at day 16 or 18 of incubation on hatching parameters and embryo and post-hatch chick juvenile physiology. A total of 2400 hatching eggs produced by Cobb broiler breeders were used for the study. Blood samples were collected at day 18 of incubation, at internal pipping stage (IP), at the end of hatch (day-old chick) and at 7-day-post-hatch for T(3), T(4) and corticosterone levels determination. From 448 to 506 h of incubation, the eggs were checked individually in the hatcher every 2h for pipping and hatching. The results indicate that non-ventilation during the first 10-day shortened incubation duration up to IP, external pipping (EP) and hatch, had no effect on hatchability and led to higher T(3) levels at IP but lower corticosterone levels at 7-day-post-hatch. The injection of dexamethasone at days 16 and 18 of incubation affected hatching and blood parameters in both the ventilated and non-ventilated embryos differentially and the effect was dependent on the age of the embryo. Dexamethasone increased T(3) levels and T(3)/T(4) ratios but the effect was greater with early non-ventilation of eggs. Dexamethasone decreased hatchability but the effect was greater when injected at day 16 and especially in ventilated embryos. The effects of incubation protocols and dexamethasone treatments during incubation were still apparent in the hatched chicks until 7 days of age. The changes in T(3), T(4) and corticosterone levels observed in response to the early incubation conditions and late dexamethasone treatments in this study suggest that incubator ventilation or non-ventilation may influence the hypothalamic-pituitary-adrenal axis (HPA) regulation of stress levels (in terms of plasma corticosterone levels) and thyroid function in the embryo with impact on incubation duration, hatching events and early post-hatch life of the chick. Our results also suggest that some stages of development are more sensitive to dexamethasone administration as effects can be influenced by early incubation protocols.

Effects of genotype and feed allowance on plasma luteinizing hormones, follicle-stimulating hormones, progesterone, estradiol levels, follicle differentiation, and egg production rates of broiler breeder hens.

The aim of this study was to compare and relate plasma hormone levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone (P4), estradiol (E2), and the in vitro P4 production capacity of the largest yellow (F1) follicle granulosa cells with the laying performance of 2 genotypes (a standard S line and a dwarf cross-experimental E line) maintained under ad libitum (SA, EA) or restricted (SR, ER) feeding regimens. Age-related hormone changes were determined from 4 to 50 wk, hormone changes during the ovulatory cycle were determined during lay, and changes in follicle granulosa cell P4-producing capacity in response to LH with or without growth factors were measured in vitro at different ages. The mean laying rate was similar for SR, EA, and ER but were lower for the SA. Plasma LH and FSH concentrations increased with age in all groups and peaked at puberty. Restricted feeding delayed puberty in both genotypes. Concentrations of E2 and P4 increased after puberty in all groups but delayed in restricted hens. Plasma levels of LH, FSH, P4, and E2 before and after puberty were not correlated with egg-laying performance, but peak E2 levels were. Luteinizing hormone and P4 concentrations during the ovulatory cycle showed differences that may be associated with the different laying performances of the 2 genotypes under ad libitum and restricted feeding. The increase in plasma LH concentration (from basal) during the preovulatory surge was higher in the SR than in the SA but was similar for EA, ER, and SA. The increase in P4 was also higher in SR than in the SA with no difference between EA and ER. In vitro P4 production by granulosa cells in response to LH with insulin-like growth factors, and bone morphogenetic protein-7 was different among the SA, SR, EA, and ER; the EA, SR, and ER had greater responses, and the SA had less response. The presence of insulin-like growth factors and bone morphogenetic protein-7 enhanced LH effects depending on the feeding regimen and age of hen. This finding suggests that differences in laying performances among genotypes fed at different nutritional levels may be partly due to differences in processes associated with follicular maturation modulated by gonadotropins and growth factors. It is concluded that the age at puberty is determined mainly by feed allowance, irrespective of genotype, and that differences in laying performance may be due to a combination of factors that include changes in the levels of gonadotropins or ovarian hormones and growth factors, BW, and the condition of the different genotypes under different feeding allowances.

The chicken pituitary-specific transcription factor PIT-1 is involved in the hypothalamic regulation of pituitary hormones.

Pit-1 is a pituitary-specific POU-domain DNA binding factor, which binds to and trans-activates promoters of growth hormone- (GH), prolactin- (PRL) and thyroid stimulating hormone-beta- (TSHbeta) encoding genes. Thyrotropin-releasing hormone (TRH) is located in the hypothalamus and stimulates TSH, GH and PRL release from the pituitary gland. In the present study, we successfully used the cell aggregate culture system for chicken pituitary cells to study the effect of TRH administration on the ggPit-l* (chicken Pit-1), GH and TSHbeta mRNA expression in vitro. In pituitary cell aggregates of 11-day-old male broiler chicks the ggPit-l * mRNA expression was significantly increased following TRH administration, indicating that the stimulatory effects of TRH on several pituitary hormones are mediated via its effect on the ggPit-l* gene expression. Therefore, a semiquantitative RT-PCR method was used to detect possible changes in GH and TSHbeta mRNA levels. TRH affected both the GH and TSHbeta mRNA levels. The results of this in vitro study reveal that ggPit-1 * has a role in mediating the stimulatory effects of TRH on pituitary hormones like GH and TSHbeta in the chicken pituitary.

Comparison of three lines of broiler breeders differing in ascites susceptibility or growth rate. 1. Relationship between acoustic resonance data and embryonic or hatching parameters.

Ascites is a prevalent cardiovascular disease among modern broilers with negative impacts on production and animal welfare. The peak of mortality due to ascites occurs at the end of the growing period, but the etiology of this problem may start during embryonic development. A few recent reports have demonstrated that the signs of ascites susceptibility are manifested during the late stages of incubation. In the current study, we used a nondestructive method based on egg acoustic resonance parameters [resonant frequency (RF) and damping] to establish a relationship between embryo physiological events during early development in broiler eggs and susceptibility to ascites. The hatching eggs of 3 broiler lines differing in ascites susceptibility were used for this study: ascites-resistant dam line (DAR), ascites-sensitive dam line (DAS), and ascites-sensitive sire line (SASL). These lines were selected on the basis of fast growth, high breast meat yield, and ascites induction at low temperatures such that the order of ascites susceptibility in terms of mortality was SASL >> DAS > DAR. Eggs were incubated under standard conditions in forced-draft incubators. We measured egg weights at setting, albumen pH, Haugh units (HU) at setting, and embryo weights at d 11 and 18, at internal pipping (IP), and at hatch. The durations of IP, external pipping (EP), and hatching were also determined. At 2 hourly periods during incubation, egg RF and damping were also measured. There were differences in egg weights between DAR and SASL vs. DAS, but albumen HU, albumen pH, and the ratio of yolk weight to egg weight were similar. There were differences in RF, damping, embryonic growth rates, and hatching events. Changes in resonant frequency and damping, which certainly suggest eggshell differences among lines, were not totally related to variations in physiological events during early and late embryonic development. A comparison between DAR and DAS, between DAS and SASL, or DAR and SASL indicates that sensitivity to ascites and selection for rapid growth rate in ascites-sensitive lines have different effects on embryonic parameters. We concluded that the sensitivity of broiler breeders to ascites does not influence egg internal quality, but the occurrence of ascites sensitivity in broilers could not be reliably predicted by early in ovo acoustic resonance parameters and hatching events.

Comparison of three lines of broilers differing in ascites susceptibility or growth rate. 2. Egg weight loss, gas pressures, embryonic heat production, and physiological hormone levels.

Ascites is a metabolic disorder that accounts for over 25% of overall mortality in the broiler industry. This disorder is manifested between wk 5 and 6 posthatch, but there are previous indications that predisposition may be identified during embryonic development. In this current study, we determined embryonic physiological and metabolic parameters that may be associated with ascites predisposition. For this purpose, we used broiler eggs from 3 lines that differed in ascites sensitivity. These included an ascites-sensitive dam line (DAS), an ascites-resistant dam line (DAR), and an ascites-sensitive sire line (SASL). Eggs were incubated for 21 d under standard conditions. The following parameters were measured during incubation: egg weights at setting, egg weight losses at 18 d, embryo body weights and embryo heart weights throughout development, air cell partial gas pressures (pCO2 and pO2) levels at d 18 and at internal pipping (IP); plasma triiodothyronine, thyroxine, and corticosterone levels at d 18, IP, and hatch; heat production from d 17 until hatch, hematocrit values at hatch, and posthatch growth rate to 7 d along with hematocrit values. The data obtained revealed that selection for ascites sensitivity or rapid growth rate had no consistent influence on some of these parameters such that they could be wholly associated with ascites sensitivity for predictive purposes. Whereas differences in embryonic developmental patterns were apparent throughout embryonic development, these differences in physiological and metabolic parameters may be due partly to genetic differences unrelated to ascites sensitivity.