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Brazilian Journal of Poultry Science, Volume: 23, Número: 1, Publicado: 2021
  • Use of Glutamine in Post-Hatch Feed for Broiler Chicks Original Article

    Carvalho, FB; Stringhini, JH; Leandro, NSM; Café, M; Sousa, RF; Santos, BM

    Resumo em Inglês:

    ABSTRACT Post-hatch delayed placement damages, physical and physiological development of broiler chicks. The objective of this study was to ascertain adequate levels of glutamine inclusion in post-hatch and pre-starter feed, in order to minimize the negative effects of post-hatch delayed placement on broiler chicks. The birds were distributed in a completely randomized design, with four treatments and five replicates of ten birds each. Four levels of glutamine supplementation (0, 1, 2 and 3%) were used in the pre-starter feed, which was given to the chicks in the transportation box and during the pre-starter phase. After 24 hours of access to this feed, and at 7 days of age, the chicks’ performance, yolk sac retraction, plasma glucose concentration, weight and small-intestine histomorphometry were evaluated. From seven to ten days of age, a metabolizability assay was performed. Glutamine supplementation tended to increase the use of the yolk sac, the concentration of plasma glucose (p<0.10) and the depth of the crypt in the ileum after 24 hours of life (p<0.05). There was no statistical difference between the glutamine supplementation levels, in relation to glucose, histomorphometry or metabolizability in the pre-starter phase. Glutamine concentrations did not differ in relation to performance, histomorphometry of the small intestine or metabolizability of nutrients in the pre-starter phase.
  • Tarragon (Artemisia Dracunculus L.) Could Alleviate Negative Effects of Stocking Density in Laying Hens Original Article

    Kaya, H; Karaalp, M; Kaynar, Ö; Tekçe, E; Aksakal, A; Bayram, B

    Resumo em Inglês:

    ABSTRACT The study was conducted to determine the effects of stocking density (SD, 5 or 7 layers/cage) and tarragon (Artemisia dracunculus L.) diet supplementation at four levels (0, 1.2, 6 and 12 g/kg feed) on performance, certain egg characteristics, serum, liver, egg yolk and small intestine bacteria parameters in laying hens. The experiment was carried out over a period of 8 weeks, with 192 Lohman Brown commercial hybrids at 50-w-age. The results showed that an increased SD reduced feed intake (FI; p<0.01) and egg production (p<0.05), but had no effect on the weight gain, feed conversion ratio, damaged egg ratio, egg weight and egg quality (p>0.05) parameters. The supplementation of tarragon to the diet reduced the FI and damaged egg ratio (p<0.01), and improved egg production and FCR (p<0.01). While an increased SD reduced serum total antioxidants (p<0.05), it elevated corticosterone (CORT) and total oxidant serum (TOS) (p<0.05). Tarragon was found to enhance total immunoglobulin (p<0.05), but to decreased the CORT and TOS of the serum (p<0.05). An increased SD raised the malondialdehyde (MDA) in the serum (p<0.001), liver (p<0.05) and yolk (p<0.001). Tarragon supplementation reduced MDA of the serum (p<0.05), liver (p<0.001) and yolk (p<0.001). E. coli and total Mesophilic Aerobic Bacteria counts in the small intestine were raised (p<0.001) with increased SD. Tarragon decreased (p<0.05) mesophilic aerobic bacteria. It was thus found that, tarragon supplementation can be considered generally effective in improving performance parameters, alleviating stress-induced negativities, reducing lipid peroxidation, regulating the immune system and controlling some intestinal microorganisms.
  • Probiotic Lactobacilli Improved Growth Performance and Attenuated Salmonella Typhimurium Infection Via Jak/Stat Signaling in Broilers Original Article

    Shi, H; Deng, X; Deng, Q; Liu, Z; Liu, N

    Resumo em Inglês:

    ABSTRACT This study aimed to investigate the effect of Lactobacillus plantarum DPP8 and Lactobacillus acidophilus C7282 in feed supplementation on growth performance, Salmonella invasion, inflammation, and mediating signaling in broilers infected with Salmonella Typhimurium (S. Typhimurium). A total of 240 broilers at day old were randomly allocated into four groups, orally infected with S. Typhimurium and supplemented with individual or combined Lactobacilli DPP8 and C7282 at doses of 0 (control), 1010 (individual), or 2.0 × 1010 (combination) cfu/kg of diet for 21 d. The results showed that supplementing Lactobacilli improved (p<0.05) feed intake and body weight gain and decreased (p<0.05) S. Typhimurium load in the caecum, harder gland, spleen and bursa of Fabricius. Also, the supplements decreased (p<0.05) interleukin (1β/2/4), tumor necrosis factor α and interferon γ in the serum, enhanced (p<0.05) interleukin 10, and downregulated gene expressions of inflammatory mediators including Janus kinase (Jak2/3), signal transducer and activator of transcription protein (STAT3/4/5/6) in the intestinal mucosa. In contrast, diets containing DPP8 exhibited greater effects on the inhibition of the pathogen and inflammatory response than C7282. The obtained data suggest that Lactobacilli C7282 and DPP8 can be used as feed additives to inhibit colonization and translocation of S. Typhimurium and inflammatory responses via downregulating Jak/STAT signaling in broilers.
  • Mitsuokella Jalaludinii Supplementation Improved Nutrient Utilization of Broilers Fed Low-Available Phosphorus Diet Original Article

    Tang, HC; Sieo, CC; Abdullah, N; Chong, CW; Omar, AR; Mohamad, R; Ho, YW; Yong, CY

    Resumo em Inglês:

    ABSTRACT Phytase enzyme is supplemented to poultry feed to improve phosphorus (P) availability. Mitsuokella jalaludinii, bacteria isolated from the rumen of cattle, has been reported as a cheaper alternative source of phytase. As much nutrients are trapped within the phytate complex, we hypothesized that the supplementation of M. jalaludinii phytase to poultry feed would enhance nutrient utilization by poultry. In the current study, the efficacy of freeze-dried M. jalaludinii cells (Mj) as feed supplement for broilers fed low-available phosphorus (low-aP) diet was evaluated. Day-old male Cobb raised in battery cages were assigned to three treatment groups [normal-available phosphorus diet with heat-deactivated Mj (DMj); low-aP diet with DMj; and low-aP diet with Mj], each consisting of four replicates (10 birds per replicate) for a 3-weeks feeding period. Feed intake was recorded daily from day 1-21, whereas broilers were weighted at day 1, 7, 14, and 21. Total excreta were collected at day 11-13 and 18-20. At day 21, twelve broilers from each treatment group were slaughtered to collect plasma and tibia. The results showed that Mj significantly enhanced broilers’ live weight and feed conversion ratio compared to the control groups (p<0.05). Supplementation with Mj have also enhanced the level of P, Ca, Mn, Cu, and Zn in the sera; and Ca and Mn in the tibia at day 18-20 sampling period (p<0.05). As Mj supplementation can enhance nutrient utilization particularly in broilers fed with low-aP diet, it could provide the market with another option in improving broilers’ growth rate at a lower cost.
  • Effect of Egg Weight and Patio Strategies on Hatching Traits and Subsequent Performance of the Broilers Original Article

    Yameen, RMK; Hussain, J; Mahmud, A; Saima,

    Resumo em Inglês:

    ABSTRACT Objectives of the present study were to assess the hatchery based interventions and their impact on hatching traits and subsequent performance of broilers. In total, 3000 eggs of Hubbard broiler breeders were equally divided into Small (50-55 g), Medium (56-61 g) and Large (62-70 g) eggs. The eggs from each category were distributed into 20 trays each containing 50 eggs. Each tray was considered as a replicate. At the end of the 18th day of incubation, the eggs of each weight category were divided into four different patio strategies i.e. P0, P3, P5 and P7 where feed and water were provided to the chicks for 0, 3, 5 and 7 days in the hatcher followed by conventional rearing. Data were collected for hatch window, hatching traits, growth, physical asymmetry, welfare and blood profile in broilers. Statistical analysis showed that the smaller eggs had significantly (P<0.05) shorter hatch window compared to larger and medium eggs. Hatching traits were significantly (p<0.05) better in medium eggs but the embryonic mortalities did not differ (p>0.05). The post-hatch performance was significantly (p<0.05) better in P3 birds from medium eggs. Physical asymmetry and scores of feather and gait were not affected by both treatments (p>0.05). Blood profile was also significantly (p<0.05) better in P3 birds from medium-size eggs. It was recommended that the eggs of 56-61g should be selected for better hatchability and the chicks should be provided with feed and water within the hatcher for at-least three days for optimum performance on rearing facility.
  • Effects of Medicinal Plants Extract with Antibiotic Free Diets on Broilers Growth Performance and Incidence of Muscles Abnormalities Original Article

    Mudalal, S; Zaazaa, A; Omar, J Abo

    Resumo em Inglês:

    ABSTRACT The objective of this research was to investigate the effects of a natural herb extract1 (HE) on the general growth performance and the incidence of muscle abnormalities (white striping and wooden) of broiler chicks. A total of 504 one-day old chicks (Ross 500) were used in the experiment and randomly partitioned into 3 treatments with 7 replicates in each (24 chicks per replicate). Three experimental diets (C: regular feed; T1 and T2 (supplemented with HE at levels of 0.20 and 0.30 ml/L, respectively). The herbal extract was supplemented in drinking water. Feed intake, body weight and feed conversion ratio were monitored at days 14, 28 and 42 of the feeding trial. Moreover, the yield of visceral organs, carcass cuts, and the incidence of muscle abnormalities were evaluated at different ages of slaughter (34, 41and 48 days). Results showed that weights, feed conversion ratios (FCR) and dressing percentages (DP) increased (p<0.05) in birds supplemented with herb extract compared to control birds. However, HE supplementation had no significant effects on carcass cuts and some visceral organs. Meat quality was improved by HE supplementation as the incidence of white stripping (WS) and WS plus wooden meat cases dramatically reduced, in particular at 34 days of age, day of slaughter. It can be concluded that feeding the herbal extract has significant positive effects on broilers general performance, feed efficiency and meat quality.
  • Influence of Effective Microorganism Supplementation to the Drinking Water on Performance and Some Blood Parameters of Laying Hens Exposed to A High Ambient Temperature Original Article

    Şahan, Z; Kutay, H; Çeli̇k, L

    Resumo em Inglês:

    ABSTRACT In the present study, seventy-two 30-week-old laying hens (Brown Hisex) were separated into two groups (control and treatment) and fed with a standard layer diet. In the treatment group the amount of effective microorganism (EM) added to the drinking water is equal to1000 ppm EM dose. Throughout the 8-week study period, 16 h thermoneutral (20-22 ºC) and 8 h hot (35-37 ºC) environmental temperature regime was applied daily. The results indicated that EM supplementation affected performance and some egg quality characteristics of layers exposed high environmental temperature. Feed intake and conversion ratio, yolk index, albumen index, yolk colour b, Haugh unit were decreased by supplemental EM. Serum glucose, cholesterol, triglycerides, calcium, total oxidant- antioxidant concentration were not affected by EM. It is concluded that EM supplementation in laying hens could have potential to improve feed intake and feed conversion ratio under high environmental temperature. However, supplemental EM with drinking water decreased some egg quality parameters.
  • Effect of Exogenous Emulsifier (Lyso-Phospholipid) Supplementation in the Broiler Diet, on the Feed Intake and Growth Performance During Grower Phase Original Article

    Shahid, I; Sharif, M; Yousaf, M; Ahmad, F; Virk, MR; Bilal, MQ; Anwar, U; Ali, A; Hussain, M; Chishti, MFA; Rahman, MA

    Resumo em Inglês:

    ABSTRACT The objective of this experiment was to investigate the effect of supplementation of an exogenous emulsifier (lyso-phospholipid) in the diet of growing broilers on growth performance and digestibility. A total of 1224 Ross-308 ten day old broiler chicks were distributed into two experimental treatments in such a way that each treatment had twelve replicates with fifty-one birds per replicate. Two experimental diets were formulated with and without emulsifier supplementation according to the nutrition standards of Ross 308. Feed intake and body weight gain of the broilers were measured on a daily basis and feed conversion ratio was also calculated. Nutrient digestibility was determined on the 25th day of age. Analysis of variance under completely randomized design technique was used to analyze the data. Feed intake was increased (p<0.05) by supplementation of emulsifier in the broiler diet on theat 12th, 13th, 21th, 22th, 23th, 24th, and 25th days. Bodyweight gain was not affected (p>0.05) with or without emulsifier supplementation in the broiler diet during 11-25 days of life. However, feed conversion ratio was effected (p<0.05) by emulsifier supplementation and increased from days 21-25th. Nutrient digestibility (dry matter, fat, and crude protein) in the grower phase was decreased (p<0.05) by supplementation of emulsifier in the diet. It can be concluded that supplementation of an exogenous emulsifier in the diet did not show positive effect on the growth performance during the grower phase of broilers, while nutrient digestibility showed adverse effect. Emulsifier supplementation should be tested after 25 days of the life of broilers.
  • Genetic Similarities of Escherichia Coli Isolated from Different Substrates of the Broiler Production Chain Original Article

    Teles, PFS; Boiago, MM; Frigo, A; Rampazzo, L; Araújo, DN; Kich, JD; Rebelatto, R; Furian, TQ; Stefani, LM

    Resumo em Inglês:

    ABSTRACT Brazil is the largest exporter of chicken meat and poultry farming is one of the most important productive segments, despite major losses due to the bacterium Escherichia coli, which is also a zoonotic microorganism. The objetive of this study was to isolate E. coli and to evaluate its transmissibility potential from the field to chicken meat using the Pulsed Field Gel Electrophoresis (PFGE) technique. Environmental samples (poultry litter, soil and water) were collected from broiler farms located in the South of Brazil where the majority of the Brazilian poultry production occurs. In addition, chicken meat (gizzard, heart, drumette and tulip) samples were collected from local supermarkets. As results, 47.36% of the samples were positives for E. coli. Furthermore, 10 pairs of clones of E. coli were found always in the same substrate (two water-water pairs; three soil-soil pairs and five meat-meat pairs) using PFGE. These findings suggest that certain strains of E. coli may have habitat preferences, making the transfer from one substrate type to another more difficult to occur. Moreover, since no clones were found between environmental samples and chicken meat, it is possible to imply a low risk of E. coli transmissibility throughout the chicken meat production chain.
  • Phytobiotic Effect of Anacardium occidentale L. Leaves Powder on Performance, Carcass Traits, and Intestinal Characteristics in Broilers Original Article

    Martínez, Y; Tobar, LA; Lagos, HM; Parrado, CA; Urquía, AM; Valdivié, M

    Resumo em Inglês:

    ABSTRACT In order to evaluate the phytobiotic effect of cashew (Anacardium occidentale L.) leaves powder (CLP) on growth performance, carcass traits, lymphoid organ weights and cecal lactic-acid bacteria in broilers, a total of 720 unsexed broilers of the Ross 308® genetic line were distributed according to a completely randomized design with three experimental treatments, five repetitions and 48 chickens per repetitions. The experimental treatments consisted of a basal diet (DB; T0) and DB + supplementation with 0.50 (T1) and 0.75% (T2) of CLP. At 32 days, the body weight, feed intake and feed conversion ratio were not modified (p>0.05) by the experimental groups; however, T1 increased (p<0.05) the viability compared to T0. Additionally, T2 improved (p<0.05) the carcass and leg yields, although without significant changes (p>0.05) for the other edible portions. Moreover, this natural product (A. occidentale) increased (p<0.05) the ash content and the range of the red tone and decreased (p<0.05) the L* in the breast, although moisture, fat, pH, and b* were not affected by the experimental diets (p>0.05). Similarly, T1 favored (p<0.05) the growth of green bacterial colonies with a white halo, and both treatments with CLP the total cecal acid-lactic bacteria. No significant changes were observed (p>0.05) in the relative weight of the immune organs (thymus, bursa of Fabricius, and spleen). Dietary supplementation with cashew leaves powder enhanced the viability of the batch (0.5%), some edible portions (0.75%), the breast pigmentation, and the cecal beneficial bacteria count in broilers.
  • Lactobacillus spp. Strains Isolation, Identification, Preservation and Quantitative Determinations from Gut Content of 45-Day-Old Chickens Broilers Original Article

    Sorescu, I; Dumitru, M; Ciurescu, G

    Resumo em Inglês:

    ABSTRACT The objective of this study was to isolate, identify, preserve and determine the quantitative level of the Lactobacillus strains from the gut content of 45-day-old chickens broilers; to test the viability of these strains preserved at 4 ºC and room temperature (20 ± 2 ºC). Lactobacillus strains were isolated, phenotypically identified and preserved from the gut content of 17 chickens broilers. Identification was performed by morphological, cultural and biochemical characters examination, using apiwebTM and ABIS online software. The quantitative level of Lactobacillus strains in intestinal content (105 - 109 CFU/g) and the viability of strains preserved at 4 ºC and at room temperature (from 8 days to 9 months) was also determined. Twenty-three strains of L. acidophilus, L. brevis, L. plantarum, L. fermentum and L. salivarius from the gut content of chickens broilers were isolated, phenotypically identified, and preserved. Of these, L. plantarum, L. fermentum and L. acidophilus biotype 1 strains were technologically and ecologically suitable to continue the testing of probiotic traits.
  • The Effect of Early Post Hatch Feeding Times on the Growth and Development of the Gastrointestinal Tract of Mule Ducklings to Five Days of Age Original Article

    Williams, MA; Lallo, CHO; Sundaram, V

    Resumo em Inglês:

    ABSTRACT The present study evaluated the effects of early post-hatch feeding on the growth and development of the gastrointestinal tract (GIT) of mule ducks reared in the humid tropics to five days of age. A total of 120 newly hatched mule ducklings were selected and randomly assigned to four treatment groups. Each with 30 birds, (T1, T2, T3, and T4) is based on four feeding regimes (feed accessed at 3, 24, 36, and 48 hours post-hatch) for five days. The ducklings were euthanized each day and the parameters: small intestinal samples were processed for histological analysis and histometrical parameters including villi length and width, crypt width and depth, and the number of goblet cells per villus was measured, statistically analyzed using ANOVA and tabulated. The results of this study indicated that the earliest post-hatch feeding (at 3 hours post-hatch) showed the highest body weight (99.65 g), heavier (GIT) organ (p<0.05), highest duodenal length (120.71 cm), than other feeding times. The villi height of the three segments of the GIT increased (p>0.05) continuously regardless of the post-hatch feeding times. Based on the results, it was concluded that feeding at 3 hours post-hatch promoted the growth and development of the GIT faster than 24, 36, and 38 hours post hatch feeding.
  • Association Analysis Between Polymorphism of Gonadotrophin Releasing Hormone Genes and Growth Traits of Quail (Coturnix Coturnix) Original Article

    Bai, J; Dong, ZH; Lei, Y; Yang, YB; Jia, XP; Li, JY

    Resumo em Inglês:

    ABSTRACT This study investigated SNP mutation sites of Gonadotrophin releasing hormone (GnRH) gene in China yellow quail, Beijing white quail and Korean quail through PCR amplification and DNA sequencing technologies. Moreover, polymorphism of GnRH gene and its association with growth traits of quail were analyzed, aiming to get molecular markers associated to growth traits of quail, which could provide references for breeding of new quail species. According to research results, a total of 14 SNP mutation sites of GnRH were detected in China yellow quail, Beijing white quail and Korean quail, which were C71T, C108T, C168T, C178T, A184G, C206T, A209C, C215T, A252G, A279T, C281T, C293G, C339T and C458T. Except that only 2 genotypes were detected for A209C and C281T in China yellow quail and Beijing white quail, 3 genotypes were detected for all of the remaining 12 SNP mutation sites in three quail species. Of the 14 SNP sites, C71T, A209C, C215T, C281T, C293G, C339T and C458T were significantly associated with body weight (p<0.05), C71T, C108T, C168T, C178T, A184G, C206T, C215T, A252G, C293G, C339T and C458T were significantly associated with shank length (p<0.05), C71T, C215T, C293G and C458T were significantly associated with breastbone length (p<0.05), A209C and C281T were significantly associated with shank circumference (p<0.05).
  • Iron Uptake by Fungi Isolated from Arcelor Mittal -Annaba- in the Northeast of Algeria Original Article

    Bourzama, G; Ouled-Haddar, H; Marrouche, M; Aliouat, A

    Resumo em Inglês:

    ABSTRACT The Metal pollution is one of the major risks in the world nowadays. Iron is an essential metal for growth and proliferation of a vast majority of organisms, but it can be toxic to human health and other living beings in the environment at high concentrations due to its increased industrial activity. Fungi have a remarkable capacity to uptake and detoxify iron metal using different mechanisms such as bioaccumulation. Thus, the aim of this work is to study the ability of iron uptake by the fungal strains isolated from Arcelor Mittal -Annaba- in Algeria. Three strains were screened at high concentration of iron (1 g/l) and their capacity to uptake iron has been studied on Czapek Yeast Agar medium. The amounts of uptaken iron ions were estimated in the same liquid medium using Atomic Absorption Spectroscopy (AAS). The results of the iron uptake by these screened strains showed that Cladosporium cladosporioides uptakes the highest concentration of iron (347.7 ppm), Aspergillus niger was able to accumulate up to 170 ppm of this metal while, the lowest uptake of this metal was shown by Penicillium citrinum with 106.43 ppm. It was found that the spore germination of three fungal strains was low when the medium is supplemented with high concentrations of iron. This indicated the potential of these fungal strains as biological agents for removal of iron from the industrial effluents containing high concentrations of it.
  • Effects of Storage Period, Marketing Channels and Season on Internal and External Quality of Commercial Table Eggs Marketed in Riyadh City (Saudi Arabia) Original Article

    Alshaikhi, AM; Abdullatif, AA; Badwi, MA; Alsobayel, AA

    Resumo em Inglês:

    ABSTRACT Very sparse information is available regarding quality of commercial Table eggs marketed in Riyadh city. The objective of the current study was to evaluate egg quality by determining the internal and external traits of commercial Table eggs marketed in different marketing channels during the summer and winter. Commercial eggs (n = 1440) were bought from four different supermarkets and groceries during the winter and summer season 2018- 2019. A total of 30 eggs were collected monthly from each marketing channel in the winter and summer. Then, individually numbered, weighed and randomly broken down into three empirical groups and stored for 0, 7 or 14 days. The outcomes show that seven and fourteen days of storage led to significant decrease in Haugh unit values, yolk index, specific gravity, shell thickness and shell weight per unit of surface area, and increase in yolk color grade, yolk albumin ratio, yolk and albumin pH and air cell depth. Eggs acquired from supermarkets had significantly higher Haugh unit values and yolk index, and lower yolk color grades, shell density and air cell depth, than those bought from groceries. Eggs that were collected in winter season are found to have significantly higher Haugh unit values, yolk index, specific gravity, shell thickness, shell density, shell weight per unit of surface area and yolk color, and lower, yolk albumin ratio, air cell depth, albumin and yolk pH than those acquired in the summer season eggs. This study showed that the storage period, marketing channels and season play a significant role in affecting quality traits of Table eggs, also those procured from supermarkets and in the winter presented better quality than those found in groceries or in the summer, respectively.
  • Gastrointestinal Parasites in Free-Range Chicken Raised under Extensive System from the Northeast of Brazil Original Article

    Saraiva, DJ; Campina, ACC; Gonçalves, FCS; Melo-Viegas, D; Santos, ACG; Nogueira, RMS; Costa, AP

    Resumo em Inglês:

    ABSTRACT Brazilian poultry production is growing, mainly due to the cost and benefit that chicken meat provides. The importance of free-range chickens and the susceptibility, to which they are exposed, makes it necessary to know about gastrointestinal parasites and the consequences that large infections can cause for them as such as weight loss. The present study aimed to determine the occurrence of gastrointestinal parasites in free-range hens raised in an extensive regime in the municipality of Santa Rita, state of Maranhão, Brazil. The studied population was composed of adult chickens (Gallus gallus domesticus) acquired from slaughterhouses in the region. The gastrointestinal organs of each chicken were separated and subsequently conditioned in flasks containing Railliet and Henry’s solution and sent to the laboratory, to be analyzed and processed. Of the 100 chickens examined, 227 specimens of helminthes were identified, with a frequency of 32.6% for nematodes and 67.4% for cestodes. Among the nematode the following parasites were identified: Ascaridia galli (27.03%); Heterakis gallinarum (48.65%) and Subulura spp. (24, 32%). Raillietina echinobothrida (100%) was the only cestoda identified. The average infection rate by species of parasite was 1.18 for A. galli, 2.22 for H. gallinarum, 1.06 for Subulura spp. and 9.00 for R. echinobothrida. It is concluded that free-range chickens are parasitized by nematodes and cestoda.
  • Effect of Heat Stress on Expression of Main Reproductive Hormone in Hypothalamic-Pituitary-Gonadal Axis of Wenchang Chicks Original Article

    Lu, BB; Liang, W; Liang, C; Yu, ZQ; Xie, XZ; Chen, Z

    Resumo em Inglês:

    ABSTRACT The hypothalamic-pituitary-gonadal (HPG) axis is a key neuroen-docrine regulation system involved in the growth and reproduction of poultry. High-temperature conditions lead to the physiological dysfunction of target organs of the HPG axis of poultry, ultimately affecting the animals’ growth and development. In this study, we evaluated the effect of heat stress (HS) on the development of cells secreting major reproductive hormones of the HPG axis (i.e., hypothalamus, pituitary gland, ovary, and testis) of Wenchang chicks. Seventy-two one-day-old healthy Wenchang chicks were randomly divided into control (CK) and HS groups. The HS group was placed in a 40 ± 0.5°C artificial climate chamber for heat-stress treatment from 13:00 to 15:00 daily for six consecutive weeks. As development progressed, compared with the CK group, the gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels in the hypothalamus and testosterone (T) levers in the testes of male chicks in the HS group were significantly decreased at three weeks of age (p<0.05). However, GnRH levels in the hypothalamus and estradiol (E2) levels in the ovaries of female chicks in the HS group were variable and significantly lower than those of the CK group at four and five weeks of age (p<0.05). In addition, the LH and FSH levels in the pituitary gland were significantly lower than those in the CK group at two and four weeks of age and at four and six weeks of age, respectively (p<0.05). In brief, HS caused dysfunction of the corresponding target organs of the HPG axis in Wenchang chicks, and this affected the normal growth and development of the cells’ HPG axis.
  • Response of Broiler Chicks to Dietary L-Leucine Supplementation in the Starter Period Original Article

    Kratei, HM; Shahir, MH

    Resumo em Inglês:

    ABSTRACT This experiment was conducted to investigate the effects of leucine (Leu) supplementation on performance and carcass traits of broilers along with the re-evaluation of standardized ileal digestible (SID) Leu requirement of broiler chicks on days 0-14. Birds were fed seven experimental diets with SID Leu levels of 16.3 (basal), 17.3, 18.3, 19.3, 20.3, 21.3, and 22.3 g/kg. Some 280 male broiler chicks were randomly assigned to the seven dietary treatments in a completely randomized design with five replicates. Dietary SID Leu levels had significant effects on body weight gain(BWG), feed conversion ratio(FCR), carcass, and breast percentages. BWG increased (p<0.05) when the broilers fed diets with 18.3 to 21.3 g/kg SID Leu compared to the basal diet. FCR decreased (p<0.05) by dietary SID Leu levels of 18.3 to 21.3 g/kg in comparison with the basal diet. Carcass yield increased (p<0.05) by SID Leu levels of 19.3 to 21.3 g/kg. Breast percentage increased (p<0.01) when the broilers received diets with 18.3 to 22.3 g/kg SID Leu and the highest value obtained by the SID Leu level of 21.3 g/kg. Abdominal fat decreased linearly by Leu supplementation (p<0.01). Regression analysis indicated the SID Leu requirement of 18.67, 18.88, and 19.85 g/kg for BWG, FCR, and breast meat yield, respectively. It can be concluded that broiler performance characteristics, especially breast yield, improve by Leu supplementation. Based on the results, the Leu requirement of modern broilers has increased dramatically due to genetic selection for a higher growth rate.
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