Gene expression of endothelin-1 and its receptors in the heart of broiler chickens with T(3)-induced pulmonary hypertension

To investigate the effect of T₃-induced pulmonary hypertension on endothelin (ET) production and genes expression of ET-1, ET_A and ET_B receptors (ET_AR and ET_BR) during rearing, semiquantitative RT-PCR and enzyme immunometric assay were performed in the heart ventricles and serum, respectively. The ET-1 and its receptor genes were expressed in the right and left ventricles of control and T₃-treated broilers at 12, 28 and 49 days of age. There were significant (P < 0.05) reductions of the relative amounts of ET-1 (in both ventricles) and ET_AR (in the right ventricle) mRNAs at 28 and 49 days of age, in T₃-treated broilers compared to controls. The relative amounts of ET_BR mRNA in the right and left ventricles did not significantly differ between control and T₃-treated broilers at any age. The serum level of ET was significantly (P < 0.05) increased in T₃-treated chickens at 28 and 49 days of age when compared with that of the control. It is concluded that ET-1, ET_AR and ET_BR genes are normally expressed in the heart ventricles of broilers. It is likely that increased serum level of ET and decreased ET-1/ET_AR genes expression in the ventricles are involved in the heart dysfunction of broiler chickens with developmental pulmonary hypertension.     

Effect of Hoodia gordonii meal supplementation at finisher stage on productivity and carcass characteristics of Ross 308 broiler chickens

Two experiments were conducted to evaluate the effect of Hoodia gordonii meal supplementation at finisher stage on productivity and carcass characteristics of Ross 308 broiler chickens. The first experiment examined the effect of level of Hoodia gordonii meal supplementation at finisher stage (30 to 42 days of age) on productivity and carcass characteristics of chickens. Level of Hoodia gordonii meal supplementation had no effect (P > 0.05) on diet intake, growth rate, feed conversion ratio and live weight of chickens. Daily supplementation with 300 mg of Hoodia gordonii meal reduced (P < 0.05) fat pad weights by 40 % in broiler chickens The second experiment examined the effect of Hoodia gordonii meal supplementation interval on the productivity and carcass characteristics of broiler chickens. Hoodia gordonii meal supplementation interval had no effect (P > 0.05) on feed intake, growth rate, live weight, feed conversion ratio and all carcass characteristics except fat pad of broiler chickens. Daily supplementation with 300 mg of Hoodia gordonii meal/bird reduced fat pad weights of the chickens by 18 %. This could not be explained in terms of differences in feed intake, digestibility, or growth rate.     

Effect of early feed restriction on hepatic lipid metabolism and expression of lipogenic genes in broiler chickens

The study was conducted to investigate the effect of early feed restriction (ER) on lipid metabolism and mitochondrial function in the liver of broiler chickens. Newly hatched broiler chickens were randomly allocated into control and ER group which was subjected to feed restriction with feed provided on alternate days from hatch to 14 days of age (14 d), followed by ad libitum feeding until the end of the experiment on 63 d. ER group exhibited significantly lower body weight throughout the experiment. Serum concentrations of total cholesterol (TC) and high density lipoprotein cholesterol (HDLC) were significantly higher in ER group at 14 d (P < 0.05), and the higher serum TC level in ER group was also observed at 63 d. In contrast, the contents of triglyceride (TG), TC and lipoprotein lipase (LPL) activity in liver were significantly lower in ER group at 14 d (P < 0.05). At 14 d no significant difference was detected for the mRNA expression of the acetyl-CoA carboxylase-α (ACC-α), carnitine palmitoyltransferase I (CPT-I), sterol regulatory element binding protein-1c (SREBP-1c) or peroxisome proliferator-activated receptors α (PPAR-α) between control and ER group. At 63 d ACC-α mRNA expression was significantly down-regulated accompanied with a significantly up-regulated CPT-ImRNA and a decreased tendency of SREBP-1c mRNA expression in ER group (P = 0.09). Swollen mitochondria with fragmented and reduced cristae were observed in liver of ER group at 14 d. Meanwhile the inner mitochondria membrane viscidity increased and hepatic mitochondrial superoxide dismutase (SOD) activity decreased at 14 d. The results suggest that feed restriction at early postnatal stage may produce long-term effect on lipid metabolism of broiler chicken, probably through, at least in part, alterations in mitochondria morphology and function.     

Response of Thai indigenous crossbred chickens to various dietary protein levels at different ages

The objective of this study was to evaluate the protein requirement of Korat chicken (KRC), a slow-growing cross strain between the Thai indigenous fighting cock (Leung Hang Khoa) and the modern genotype females. Four periods were considered: from hatch to 21 days (phase 1), 22 to 42 days (phase 2), 43 to 63 days (phase 3), and 64 to 84 days of age (phase 4). A total of 3120 mixed-sex KRC were randomly allocated to 5 dietary protein levels containing 19, 20, 21, 22, and 23% with 2978 kcal of ME/kg (900 birds in phase 1); 18, 19, 20, 21, and 22% with 3151 kcal of ME/kg (780 birds in phase 2); 16, 17, 18, 19, and 20% with 3200 kcal of ME/kg (720 birds in phase 3); and 15, 16, 17, 18, and 19% with 3200 kcal of ME/kg (720 birds in phase 4) with 6 replicates in a completely randomized design. The results showed that BW, BW gain, average daily gain (ADG), and protein intake (P?<?0.05) were increased with increasing dietary protein (P?<?0.05) in all phases. However, FI, feed cost per kg of BW gain, energy intake, and blood urea nitrogen of chickens were not found to be significantly different among treatments. On the other hand, increasing dietary protein levels depressed the protein efficiency ratio of chickens from hatch to 21 and from 64 to 84 days of age (P <?0.05), and tended to decrease it from 22 to 42 (P?=?0.08) and from 43 to 63 (P =?0.07) days of age as well. According to a broken-line regression analysis, the protein requirements of chickens from hatch to 21 and from 22 to 42 days of age for maximum BW gain were 21.26 and 20.45%, respectively. While the requirements of maximum responses for BW gain and FCR in the period of 43 to 63 days of age were 18.00 and 18.04%, respectively, and in the period of 64 to 84 weeks of age were 17.94 and 18.03%, respectively.

     

Packed cell volume reference intervals to aid in the diagnosis of anemia and polycythemia in young broiler chickens.

Packed cell volume (PCV) reference intervals were established for use in diagnosing anemia and polycythemia in young broiler chickens. Blood samples were collected from one hundred twenty 3-to-49-day-old clinically healthy conventionally reared broiler chickens. PCVs were determined and analyzed. PCVs regressed significantly (P less than 0.025) on age, which shows that neonatal physiologic anemia occurs in broiler chickens, as well as in mammals and specific-pathogen-free (SPF) chickens. The definition for anemia in broiler chicks varies with age. We defined anemia as a PCV less than or equal to 26%, 29%, 33%, 32%, 33%, 33%, 31%, and 28% for broiler chickens, 3, 7, 14, 21, 28, 35, 42, and 49 days old, respectively. We define polycythemia as a PCV greater than or equal to 42%, 43%, 41%, 40%, 42%, 42%, 41%, and 40% for broiler chickens 3, 7, 14, 21, 28, 35, 42, and 49 days old, respectively. Otherwise, broiler chickens have PCVs within established reference intervals. Results provide guidelines for detecting anemia and polycythemia in young broiler chickens of various ages.     

The response of Ross 308 and Hybro broiler chickens to early and late skip-a-day feed restriction

The effects of skip-a-day feeding for 14 days during the starter or grower period or for 28 days during both periods followed by ad libitum feeding to market age on the growth performance of two strains of broiler chickens, Ross 308 and Hybro, were studied over 7 weeks. Ross was superior to Hybro in weight gain, final body weight and feed conversion but consumed more feed. Overall, feed restriction reduced feed intake, weight gain and body weight in all feed - restricted birds. Also, the 14-day feed-restricted birds gained more weight and were heavier than the 28-day restricted ones. Feed restriction neither improved feed conversion nor reduced abdominal fat but decreased mortality rate. Strain | treatment interaction significantly affected only feed intake. It is suggested that for broiler chicken production in the tropics Ross 308 could be used and feed restricted for 14 days during the starter or grower period.     

Preparation and evaluation of chicken embryo-adapted fowl adenovirus serotype 4 vaccine in broiler chickens

The current study was planned to develop an efficient vaccine against hydropericardium syndrome virus (HSV). Currently, formalin-inactivated liver organ vaccines failed to protect the Pakistan broiler industry from this destructive disease of economic importance. A field isolate of the pathogenic hydropericardium syndrome virus was adapted to chicken embryos after four blind passages. The chicken embryo-adapted virus was further serially passaged (12 times) to get complete attenuation. Groups of broiler chickens free from maternal antibodies against HSV at the age of 14 days were immunized either with 16th passage attenuated HSV vaccine or commercially formalized liver organ vaccine. The antibody response, measured by enzyme-linked immunosorbent assay was significantly higher (P < 0.05) in the group immunized with the 16th passage attenuated HSV vaccine compared to the group immunized with liver organ vaccine at 7, 14, and 21 days post-immunization. At 24 days of age, the broiler chickens in each group were challenged with 10^3.83 embryo infectious dose₅₀ of pathogenic HSV and were observed for 7 days post-challenge. Vaccination with the 16th passage attenuated HSV gave 94.73% protection as validated on the basis of clinical signs (5.26%), gross lesions in the liver and heart (5.26%), histopathological lesions in the liver (1.5 ± 0.20), and mortality (5.26%). The birds inoculated with liver organ vaccine showed significantly low (p < 0.05; 55%) protection estimated on the basis of clinical signs (40%), gross lesions in the liver and heart (45%), histopathological lesions in the liver (2.7 ± 0.72), and mortality (35%). Birds in the unvaccinated control group showed high morbidity (84%), mortality (70%), gross (85%), and histopathological lesions (3.79 ± 0.14) with only 10% protection. In conclusion, this newly developed HSV vaccine proved to be immunogenic and has potential for controlling HSV infections in chickens.     

Correlation analysis of hypothalamic mRNA levels of appetite regulatory neuropeptides and several metabolic parameters in 28‐day‐old layer chickens

Various lines of evidence suggest that appetite‐related neuropeptides in the hypothalamus are regulated by adiposity signals such as leptin and insulin in mammals. In the present study, we examined age‐dependent changes in the weight of abdominal fat and hypothalamic mRNA levels of neuropeptide Y (NPY, an orexigenic neuropeptide) and proopiomelanocortin (POMC, a precursor of anorexigenic neuropeptides) in growing chickens at 7, 14, 21 and 28 days of age. Hypothalamic NPY mRNA levels were significantly (P < 0.05) decreased after 14 days of age, whereas hypothalamic POMC mRNA levels were significantly (P < 0.05) increased at 28 days of age. The percentage of abdominal fat was significantly increased after 14 days of age in chickens. We next examined the correlation of hypothalamic NPY and POMC mRNA levels and several parameters at 28 days of age. There were no significant correlations between hypothalamic mRNA levels of NPY or POMC and the percentage of abdominal fat. These findings suggest that the gene expressions of NPY and POMC do not depend on adiposity in chickens, at least in 28‐day‐old layer chickens.     

Intestinal microbiota of broilers submitted to feeding restriction and its relationship to hepatic metabolism and fat mass: Fast‐growing strain

The present study was conducted to verify how feed restriction affects gut microbiota and gene hepatic expression in broiler chickens and how these variables are related to body weight gain. For the experiment, 21‐d‐old Cobb500^TM birds were distributed in a completely randomized experimental design with three treatments: T1. Control (ad libitum—3.176 Mcal/kg ME—metabolizable energy—and 19% CP—crude protein); T2. Energetic restriction (2.224 Mcal/kg ME and 19% CP) from 22 to 42 days with consumption equivalent to control; T3. Quantitative restriction (70% restriction, i.e., restricted broilers ingested only 30% of the quantity consumed by the control group—3.176 Mcal/kg ME and 19% CP) for 7 days, followed by refeeding ad libitum from 28 to 42 days. Ileum and caecum microbiota collections were made at 21, 28 and 42 days of age. Hepatic tissue was collected at 28 and 42 days old for relative gene expression analyses. At 43‐d‐old, body composition was quantified by DXA (Dual‐energy X‐ray Absorptiometry). Both feed restriction programmes decreased Lactobacillus and increased Enterococcus and Enterobacteriaceae counts. No differences were found in the refeeding period. Energetic restriction induced the expression of CPT1‐A (Carnitine palmitoyltransferase 1A) gene, and decreased body fat mass. Quantitative feed restriction increased lipogenic and decreased lipolytic gene expression. In the refeeding period, CPT1‐A gene expression was induced, without changing the broilers body composition. Positive associations were found between BWG (Body Weight Gain) and Lactobacillus and Clostridium cluster IV groups, and negatively associations with Enterobacteriaceae and Enterococcus bacterial groups. In conclusion, differences found in microbiota were similar between the two feed restriction programmes, however, hepatic gene expression differences were only found in quantitative restriction. Higher counts of Lactobacillus and Clostridium cluster IV groups in ileum are likely to be related to better broiler performance and low expression of lipogenic genes.     

The antimicrobial activity of lavender essential oil (Lavandula angustifolia) and its influence on the production performance of broiler chickens

The aim of the study was the evaluation of the antimicrobial activity (in vitro) of lavender (Lavandula angustifolia) essential oil (LEO) and the effect of its addition to the drinking water of broiler chickens on their production performance. Antimicrobial activity was determined by establishing the minimum inhibitory concentration (MIC) using a series of microdilutions. Bird experiments were carried out on a commercial farm on 300 Ross 308 broilers. One‐day‐old chicks were randomly assigned to three experimental groups of 100 individuals (five replications of 20 individuals each). In the control group, chickens received drinking water without added essential oil throughout the rearing period. In the LEO_0.2 and LEO_0.4 groups, from 1 to 42 days of bird life, the LEO_0.2 group had 0.2 ml/L of essential lavender oil added to the drinking water, while LEO_0.4 had 0.4 ml/L added. The results of the experiment showed the antimicrobial activity of LEO and its positive effect on the production results of broiler chickens. Application of higher concentration of essential oil (0.4 ml/L) significantly affected production results (BW, FCR, WCR—p < .01). No differences were observed in FI, WI, F:W and mortality (p > .05). In vitro studies indicate a significant effect of LEO on the inhibition of microbial growth. These results encourage further studies on a larger scale that will confirm antimicrobial efficiency and define the mechanisms of action of Lavandula angustifolia essential oil and its individual components.     

The effect of dietary supplementation with globin and spray-dried porcine plasma on performance,digestibility and histomorphological traits in broiler chickens

This study evaluated the effects of globin and spray-dried porcine plasma (SDPP) on growth performance, digestibility, nitrogen retention, energy retention efficiency (ERE) and intestinal morphology of broiler chickens. A total of 336-day-old male broiler chickens were reared from 1 to 40 days of age and fed 3 diets (8 replicates/diet, 14 birds/replicate) during 3 feeding phases: starter (1–12 days), grower (12–25 days) and finisher (25–40 days). Isonitrogenous diets were formulated by replacing gluten protein isolate contained in the control diet (C diet) with 2% (starter) or 1% (grower and finisher) spray-dried porcine plasma in the plasma diet (SDPP diet). The globin diet (G diet) was obtained by adding globin on the top of C diet at a dose of 0.08% for the whole rearing period. Total tract apparent digestibility (aD), nitrogen retention and ERE were assessed during the three growing phases. At 12  and 40 days of age, one bird per pen was slaughtered to sample gut, liver, spleen and bursa of Fabricius for histomorphological investigations. The SDPP diet increased body weights of chickens at 12 (+60 g; p < .001), 25 (+101 g; p < .001) and 40 days (+130 g; p = .018) of age compared to C and G diets. Also SDPP improved crude protein aD (+9.7%) and ERE (+12.3%) during the starter phase (p < .001). Dietary globin and SDPP inclusion did not affect either the gut morphology or the histopathological findings in birds at 12 and 40 days of age, despite a numerical (+6.90% and +7.40% respectively) villus height improvement in the SDPP group. Overall, these results confirm that dietary supplementation with SDPP and, to a lesser extent, with globin can improve growth performance and dietary protein and energy utilization in broiler chickens without effect on gut functionality.     

Effects of thermo‐resistant non‐starch polysaccharide degrading multi‐enzyme on growth performance,meat quality,relative weights of body organs and blood profile in broiler chickens

This research was conducted to study the performance and carcass parameters of broiler chickens fed diets supplemented with heat‐treated non‐starch polysaccharide degrading enzyme. A total of 432 one‐day old Ross 308 broiler chickens were allocated to five treatments: (i) CON (basal diet), (ii) E1: CON + 0.05% multi‐enzyme, (iii) E2: CON + 0.1% multi‐enzyme, (iv) E3: CON + 0.05% thermo‐resistant multi‐enzyme and (v) E4: CON + 0.1% thermo‐resistant multi‐enzyme, each treatment consisted of six replications and 12 chickens in each replication. The chickens were housed in three floor battery cages during 28‐day experimental period. On days 1–7, gain in body weight (BWG) improved by feeding the diets supplemented with thermo‐resistant multi‐enzyme. On days 7–21 and 1–28, chickens fed the diets containing thermo‐resistant multi‐enzyme showed improved (p < 0.05) BWG and feed conversion ratio (FCR) compared to CON group. Supplementing the diets with multi‐enzyme or thermo‐resistant multi‐enzyme affected the percentage of drip loss on d 1 (p < 0.05). Drip loss percentage on days 3 and 5 and also meat colour were not affected significantly. Supplementing the diets with multi‐enzyme or thermo‐resistant multi‐enzyme did not affect the relative weights of organs but compared to CON group, relative weight of breast muscle increased and abdominal fat decreased (p < 0.05). Among measured blood constituents, chickens fed supplemented diets with thermo‐resistant multi‐enzyme showed higher (p < 0.05) IgG. Counts of red and white blood cells and lymphocyte percentage were not affected. In conclusion, the results demonstrated that supplementing pelleted diets with thermo‐resistant multi‐enzyme improved performance of broiler chickens.     

Diminished gene expression of cardiac heat shock proteins in pulmonary hypertensive chickens

1. The relative expression of heat shock protein (HSP) genes (HSP60, HSP70 and HSP90) was performed using quantitative real-time PCR on tissue from the heart ventricles to investigate the effect of 3,5,3′-l-triiodothyronine (T₃)-induced pulmonary hypertension in broiler chickens.

2. The ratio of the right ventricle to total ventricle (index of pulmonary hypertension) was increased in the treated groups at 12 and 42 d of age compared to controls but was significant only at 42 d.

3. The HSP genes were expressed in the right and left ventricles of control but T₃-treated broilers at 12 and 42 d of age. The relative amounts of HSP60 and HSP90 gene expression in the right ventricle of treated groups were significantly increased at 12 d and decreased at 42 d of age compared to controls.

4. Variations of HSP60 and HSP90 mRNAs in the left ventricle were not significant. The relative amount of HSP70 mRNA expression in the right and left ventricles of treated groups was significantly decreased at 42 d of age compared to controls. HSP70 mRNA expression did not differ between the right and left ventricles at 12 d of age.

5. It is concluded that gene expression of HSPs (i.e. HSP60 and HSP90) was upregulated in the heart of chickens developing pulmonary hypertension syndrome, probably to delay the pathological process of disease. The right ventricle from hearts of pulmonary hypertensive chickens showed considerable reductions of HSP60, HSP70 and HSP90, which is evidence of a loss of compensatory responsiveness in dilated heart.     

Effects of dietary inclusion levels of palm oil on growth performance,antioxidative status and serum cytokines of broiler chickens

This study was conducted to investigate the effects of dietary palm oil inclusion levels on growth performance, serum antioxidative status and cytokines in Sanhuang broiler chickens. A total of 208 one‐day‐old female Sanhuang chickens were randomly allocated to four treatment groups with four replicates per group and of 13 birds each for a 42‐day feeding trial. Dietary treatments were basal diet without palm oil (control) and diets containing 2%, 4% or 6% palm oil. During days 22 to 42 and the overall experimental period, chickens fed diets supplemented with 4% and 6% palm oil had a lower average daily feed intake (ADFI) (p = 0.019) and feed to gain ratio (F/G) (p = 0.031). Average daily gain (ADG) tended to be higher (p = 0.089) for palm oil inclusion treatments compared with the control treatment from days 1 to 42. Dietary 2% and 4% palm oil treatments significantly lowed serum malondialdehyde concentration on day 21 when compared to the control and 6% palm oil treatments (p = 0.027). Dietary 6% palm oil treatment significantly reduced the catalase (CAT) activity (p = 0.018) and total antioxidant capacity (T‐AOC) (p = 0.027) in serum in comparison with the control treatment on day 21. No significant differences were observed in superoxide dismutase (SOD) and glutathione peroxidase (GSH‐Px) activities in serum among dietary treatments on day 21. There were no significant differences in T‐AOC, CAT, SOD and GSH‐Px activities among dietary treatments on day 42. Dietary inclusion of 4% and 6% palm oil significantly increased (p = 0.01) serum interleukin‐1β (IL‐1β) content, but improved transforming growth factor‐β (TGF‐β) content in serum on both days 21 and 42 (p = 0.032 and 0.022 respectively) as well as IL‐10 content on day 42 (p = 0.022) when compared with the control treatment. Furthermore, dietary inclusion of 6% palm oil significantly reduced tumour necrosis factor‐α (TNF‐α) content on days 21 and 42 (p = 0.021 and 0.001 respectively) compared with the control treatment. These results suggest that dietary inclusion of 4% and 6% palm oil could improve the growth performance, modulate the balance between pro‐ and anti‐inflammatory cytokines, and show limited effect on antioxidative status in Sanhuang broiler chickens.     

Yellow mealworm,Tenebrio molitor (Col: Tenebrionidae), larvae powder as dietary protein sources for broiler chickens: Effects on growth performance,carcass traits,selected intestinal microbiota and blood parameters

This study was conducted to evaluate the effects of dietary Tenebrio molitor larvae meal (TM meal) inclusion on the performance, carcass traits, caecum microbiota and blood parameters of broiler chickens. A total of 180-day-old chickens were allocated to three dietary groups with five replicate pens (12 birds/pen). Experimental diets were included a corn-soybean basal diet, and two diets with 2.5% and 5% TM. TM-included diets have been administered for periods of starter (1–10 days) and grower (11–25 days). A regular finisher diet was given to all groups during the 26–42 days of age. Diets containing TM meal did not influence feed intake and mortality percentage. Feed conversion ratio was lower with the 2.5% TM meal diet compared with the control group at starter period (p < .05). Besides, broiler chickens fed TM meal included diet had a higher body weight gain than the control group during 1–10 days of age (p < .05). The carcass characteristics and length and weight of different parts of small and large intestines were not influenced by diets. TM meal inclusion decreased the albumin-to-globulin ratio compared with the control group (p < .05). Additionally, lower total count of aerobic and Escherichia coli bacteria was observed in response to diet inclusion of 5% TM meal. Overall, the inclusion of TM meal in broilers' diet improved body weight gain and feed conversion ratio in the starting period, decreased albumin-to-globulin ratio and E. coli bacteria content.     

Oral vaccination of chickens against Newcastle disease with I-2 vaccine coated on oiled rice

Antibody response produced by Newcastle disease virus (NDV, strain I-2) when given orally through oiled rice to chickens was determined. Serum samples were collected before and at a weekly interval for 28 days after vaccination and tested for haemagglutination inhibition (HI) antibody to NDV. The results showed 7 days after vaccination HI antibody titre log₂ was 3.8. Moreover, 14 and 28 days after vaccination HI antibody titre log₂ reached 6.5 and 8.0, respectively. All unvaccinated chickens were negative to NDV antibody throughout the study. Significant finding from the present study is that 7 days after vaccination chickens had produced protective antibody against NDV; this is in contrast to previous studies. Therefore, I-2 vaccine coated on the oiled rice is efficacious as it protects chickens from challenge with NDV. Wambura, P. N., 2008. Oral vaccination of chickens against Newcastle disease with I-2 vaccine coated on oiled rice. Tropical Animal Health and Production.     

Growth performance and intestinal morphology of Hyline chickens fed diets with different diet particle sizes

The effect of feed particle size on the growth performance and intestinal morphology of Hyline chickens was studied. Sixty one‐day‐old chickens were randomly assigned into two groups with five replicates per group and six chickens per replicate. The control group (CG) was fed pelleted feed and the experimental group (EG) was fed crumbled feed. The geometric mean diameter (GMD) of the pelleted and crumbled feed was approximately 1.2 and 0.8 mm respectively. The trial was carried out from day 15 to day 69 of the lives of the chickens. During the experimental period, the average daily feed intake (ADFI), average daily gain (ADG) and feed conversion rate ( FCR) were calculated. At 42 and 69 days of age, fifteen chickens from each group were slaughtered for the intestinal morphology analyses. The morphologies of various segments of the intestine were observed by scanning electron microscopy (SEM). The results showed that from 15 to 42 days of age, the FCR of the CG was higher than that of the EG, but the final body weight was lower in the CG than in the EG (p < 0.05). The villi heights in the duodenum, jejunum and ileum were shorter in the CG than in the EG (p < 0.05). The villi tips in the duodenum and jejunum of the CG were broken, but they were protected in the EG. At 69 days of age, the BW and the whole intestinal villi height of the CG were greater than those of the EG (p < 0.05). The villi in the duodenum and jejunum in the CG were better than 42 days, but the tips of the duodenal villi in the EG were slightly broken. In conclusion, feeding chickens crumbled feed from 15 to 42 days of age and then feeding them pelleted feed was beneficial to the growth performance of the Hyline chickens, as the pelleted feed would break the intestinal villi of young chickens, but the intestinal villi become stronger with the chicken growth.     

Effects of dietary fiber and threonine on performance,intestinal morphology and immune responses in broiler chickens

The present experiment was conducted to investigate the effects of fiber and threonine (Thr) on growth performance, intestinal morphology and immune responses of broiler chickens. A total of 420 one-day-old mixed sex broiler chicks (Ross 308) were randomly divided into 6 experimental diets and 5 replicates of 14 chicks based on a factorial arrangement (2 × 3) from 1 to 42 d of age. Experimental factors included dietary supplemental fiber type (no supplemental fiber [NSF], 30 g/kg sugar beet pulp [SBP] or 30 g/kg rice hull [RH]) and Thr inclusion level (100% or 110% of Thr requirement recommended by breeder company [Ross 308]). Growth performance of broilers was assayed at different periods of the experiment. Intestinal morphometric features were measured at 21 d of age. Antibody titer against sheep red blood cells (SRBC), Newcastle and influenza disease viruses were measured on d 30 of trial. Dietary inclusion of SBP and RH significantly decreased feed intake and weight gain during the entire rearing period (P < 0.05). Interaction of fiber and Thr had no beneficial effects on the performance of chickens across the entire rearing phase. Dietary supplementation of 110% Thr required level improved jejunal morphometric features (P < 0.05), whereas its inclusion with fibrous materials failed to show the same effects. Dietary supplemental Thr together with SBP significantly increased antibody production against SRBC (P < 0.05). In conclusion, although supplemental 30 g/kg fibrous materials impaired growth performance, inclusion of SBP along with 110% Thr level improved the humoral immunity in broiler chickens.     

Protein digestive dynamics of meat and bone meals in broiler chickens

This study determined the variations in protein digestibilities and digestion rates in broiler chickens offered diets containing 7 different meat and bone meals (MBM). A total of 252 male Ross 308 broiler chickens were offered 7 atypical diets largely based on maize and MBM from 24 to 28 d post-hatch. Each experimental diet was offered to 6 replicates with 6 birds per replicate cage. Excreta were collected in their entirety from 25 to 27 d post-hatch and on 28 d post-hatch. Digesta samples were collected from the proximal jejunum, distal jejunum, proximal ileum and distal ileum. Apparent digestibilities of protein were determined in each segment and apparent digestibilities of amino acids were measured in the distal ileum. There were significant differences in apparent protein digestibility coefficients in the proximal jejunum (P = 0.006), where broiler chickens offered the high ash beef meal (diet 7) generated the lowest protein digestibility in the proximal jejunum (0.318). Similarly, there were significant differences in apparent digestibility coefficients in the distal jejunum (P < 0.001) and distal ileum (P < 0.001) but not in the proximal ileum. More pronounced differences were found in the disappearance rate of protein and there were significant differences in all 4 segments of the small intestine (P < 0.001). Broiler chickens offered the high ash beef meal had the lowest protein disappearance rate (P < 0.001). No difference was observed in the predicted protein digestion rate (P = 0.486) but chickens offered the high ash beef meal had the lowest potential digestible protein (0.662, P = 0.034) whereas the highest potential digestible protein (0.739) was detected in diet 5 (containing a beef meal). This study contributed to the establishment of a preliminary database to include digestion rates of starch and protein into practical diet formulation.