Assessment of interactions between glutamine and glucose on meat quality,AMPK, and glutamine concentrations in pectoralis major meat of broilers under acute heat stress

The objective of this experiment was to evaluate the effects of dietary glutamine and glucose on pectoralis major meat quality in broilers under acute heat stress. Three hundred 35-day-old male broilers (Arbor Acres) were randomly divided into 5 groups. Broilers in the positive control group were kept in a thermoneutral environment (23 ± 1°C, RH 45%–55%) and fed a basic diet, whereas the experimental (2 × 2) group was exposed to acute heat stress (34 ± 1°C, RH 65%–75%) for 12 h and fed the basic diet that contained glutamine (0 and 10 g/kg) and glucose (0 and 10 g/kg). Compared with the positive control group, acute heat stress without glutamine and glucose supplementation increased (P < 0.05) drip loss, L* values, and AMPK concentrations, but it decreased (P < 0.05) water-holding capacity, moisture, pH, a* values, b* values, and glutamine concentrations in pectoralis major meat of chickens. However, dietary glutamine (10 g/kg) increased (P < 0.05) water-holding capacity, moisture, pH, a* values, b* values, and glutamine concentrations, while it decreased (P < 0.05) drip loss, L* values, and AMPK concentrations in heat-stressed chicken pectoralis major meat. Dietary glucose (10 g/kg) increased (P < 0.05) water-holding capacity, moisture, pH, and a* and b* values, while it decreased (P < 0.05) L* values and AMPK concentrations of pectoralis major meat in chickens exposed to acute high temperature. There were significant interactions between glutamine and glucose in the water-holding capacity, pH values, AMPK, and glutamine levels of pectoralis major meat in the heat-stressed chickens. The above results suggest that the addition of glutamine and glucose in the diet is necessary for broilers during acute heat stress condition.     

日粮中添加包被肉桂油对肉鸡屠宰性能、肌肉品质和风味的影响

为探究鸡日粮中添加包被肉桂油对肉鸡生长性能、屠宰性能、肌肉品质和肌肉风味的影响,试验选用168只1日龄罗斯308雏鸡,随机分成2个处理组,对照组饲喂基础日粮,试验组在基础日粮中添加300 mg/kg的包被肉桂油。结果显示:与对照组相比,试验组肉鸡活体重没有显著的差异(P>0.05);21日龄胸肌的a^*值和b^*值(P<0.05)和42日龄胸肌和腿肌的24 h pH值(P<0.05)提高,21和42日龄胸肌和腿肌的滴水损失(P<0.05)降低;21日龄胸肌中过氧化氢的含量和42日龄胸肌丙二醛含量(P<0.01)降低;腿肌中的甜味氨基酸(丝氨酸和甘氨酸)(P<0.05)和芳香族氨基酸(酪氨酸和苯丙氨酸)的含量(P<0.01)提高。研究表明:日粮中添加300 mg/kg的包被肉桂油能够改善肉鸡肌肉品质的部分指标,提高胸肌抗氧化力和腿肌风味。     

Dietary Supplementation with Microencapsulated Lutein Improves Yolk Color and Lutein Content in Fresh and Cooked Eggs of Laying Hens

This study was conducted to compare the efficacy of diet supplemented with non-microencapsulated lutein (NL) and microencapsulated lutein (ML) in laying hens. A total of 270 Hy-line Brown laying hens (54 weeks old) were allocated to three groups with six replicates of 15 hens and were adapted to a wheat-soybean meal basal diet for two weeks. Next, the control birds were fed the basal diet, and the test birds were fed the basal diet supplemented with 600 mg/kg NL (12 mg/kg available lutein) or 90.1 mg/kg ML (10 mg/kg available lutein) for 35 days. Supplementation of lutein did not affect the productive performance of laying hens, but improved (P<0.05) the yolk color and red/green value (a*), with eggs from the ML group displaying improved color and a* values from the 15^th day of the experimental period. The blue/yellow value (b*) for the yolk showed an increase (P<0.05) through both NL and ML supplements. The yolk color of fried and boiled eggs and a* value of the yolk in fried eggs were improved (P<0.05) only through ML supplemented diet. Both NL and ML supplements resulted in lower (P<0.05) lightness and higher (P<0.05) a* values of yolk in boiled eggs, as well as higher (P<0.05) b* values in fried and boiled eggs. Yolk lutein content in fresh, fried, and boiled eggs was increased (P<0.05) in NL and ML groups with the latter being higher. In conclusion, ML improved yolk pigmentation and lutein retention in laying hens better than NL.     

Skin Pigmentation Evaluation in Broilers Fed Different Levels of Natural Okra and Synthetic Pigments

Broiler carcass skin color is important in China, the United States, Mexico, and other countries. The present study evaluated the use of natural and synthetic pigments in broiler diets at different commercial levels. The experiment included 288 fifty-day-old Da-Ma-Hua birds, divided into 6 treatments. Birds in 4 treatments were fed a basal diet consisting of 2, 3, 4, or 5% okra [Abelmoschus esculentus (L.) Moench Meth., also known as abelmosk or ram-horn bean] meal, respectively. Birds in another treatment received a basal diet without okra, and birds in a sixth treatment were fed a blend of 25 g/metric ton of 10% canthaxanthin and 50 g/metric ton of 10% carotenoic acid, β-apo-8′-ethylesters. Each treatment consisted of 3 replicates of 16 birds each. The experiment lasted 6 wk. Skin color was measured with a Kemin color fan after slaughter and chilling at wk 2, 3, 4, 5, and 6 of treatment. Pigmentation of the chicken skin and abdominal fat were significantly improved (P < 0.05) in the 4 and 5% okra treatments. The pigmentation effect reached a satisfactory level after 4 wk of treatment. The rank of pigmentation in different parts of the body of a bird was shank > breast > abdomen > back. The addition of okra meal had no significant influence on daily gain or the feed-to-gain ratio (P > 0.05). This study shows that xanthophyll-rich okra meal can be used as a natural pigment source in poultry feed, which may allow pigment use and feed costs to be reduced.     

Effects of phytonutrients on growth performance,antioxidative status,and energy utilization of broilers fed low energy diets

Two experiments were conducted to investigate the effects of phytonutrients (PN) on growth performance, antioxidant status, intestinal morphology, and nutrient utilization of birds fed low energy diets. In Exp. 1, a total of 1,440 one-day-old Ross 308 male broiler chickens were randomly divided into 3 treatment groups, with 16 replicates per treatment (48 pens; 30 birds per pen). Birds in treatment 1 were fed diets with normal energy content (NE). Birds in treatment 2 were fed NE diet but with 60 kcal removed (LE). Birds in treatment 3 were assigned to LE diet supplemented with PN (LE + PN). Results indicated that LE diet increased feed conversion ratio (FCR) compared with NE from d 1 to 38, while LE + PN diet prevented this response (P = 0.02). At d 26, birds in the LE + PN group had the highest ileal and jejunal villus height to crypt depth (VH:CD) ratio. At d 39, PN supplementation improved ileal and jejunal VH:CD ratio, compared with LE group. Moreover, birds fed PN diets received a better economic profit. In Exp. 2, 360 one-day-old Ross 308 male broiler chickens were used in a metabolism study. The treatments used in Exp. 2 were the same as those in Exp.1, with 4 replicates (pens) and 30 birds in each replicate. Dietary apparent metabolism energy (AME), energy and protein digestibility were determined between 21 and 28 d of age. Results showed that chickens fed LE + PN diet tended to have greater AME (P = 0.02) and nitrogen-corrected apparent metabolism energy (AMEn) (P = 0.03) than birds fed LE diets. It was concluded that LE + PN showed a potential advantage to improve feed conversion and gut health of broilers, as well as economic profits.     

Sensorial quality and bone strength of female and male broiler chickens are influenced by weight and growth rate

1. An experiment was conducted with 98 male and 98 female broiler chickens (Ross 308) to study the effect of growth rate, induced by different dietary means, sex and live weight (1500?g and 2000?g) at slaughter on production parameters, bone strength and sensorial characteristics of the breast meat.

2. The birds were divided into four groups and individually fed a standard commercial diet, a high energy diet or low energy diet from d?11 to slaughter at between d 28 and 39. Three groups were fed ad libitum and a further group was fed a restricted amount of the high energy feed. Half of the birds in each group were slaughtered at approximately 1500?g and the other half at 2000?g live weight.

3. The diets resulted in different growth rates. The chickens fed the high energy and the commercial diet had the highest growth rate at both live weights at slaughter. The restricted fed chickens had lower bone strength than the chickens fed the low energy diet.

4. Breast meat from male broilers was juicer, more tender and less hard than breast meat from females. Chickens slaughtered at 2000?g live weight were juicer than those slaughtered at 1500?g. Chickens given the high energy feed ad libitum and restricted had different growth rates, but the sensory parameter related to texture showed no difference.

5. It was concluded that an increased slaughter weight might improve meat quality due to improved juiciness.     

Effects of a New Recombinant Phytase on the Performance and Mineral Utilization of Broilers Fed Phosphorus-Deficient Diets

An experiment was conducted with Arbor Acres broiler chickens that were fed 3 experimental diets—a control diet containing an adequate level of available phosphorus (AP) and 2 diets that were deficient in AP but supplemented with phytase at a level of either 500 or 750 phytase units/kg—to assess the effects of a novel microbial phytase supplement in broilers fed AP-deficient diets on growth performance and mineral utilization. Similar average daily gain, feed intake, and feed efficiency (P > 0.05) were obtained among broilers fed different diets. Compared with broilers fed the control diet, broilers fed diets with phytase had greater (P < 0.05) retention of Ca, P, and Zn. Moreover, the levels of Cu, Zn, Mg, and Mn in the tibia bone at 28 d of age, and Zn and Mn at 42 d of age in birds fed diets with phytase exceeded (P < 0.05) those of birds fed the control diet. Supplementation of phytase increased Zn and Mg contents in the plasma at 42 d of age. Birds responded similarly to phytase supplemented at a level of 500 or 750 phytase units/kg in terms of growth performance, mineral retention, and mineral content in the serum and bone. Therefore, with the supplementation of this novel phytase, it is possible to reduce the dietary levels of P and other minerals to below the recommended levels of the Feeding Standard of Chicken in P. R. China (ZB B 43005-86).     

Growth performance,blood parameters,carcass characteristics and meat quality traits in Potchefstroom Koekoek chickens fed <Emphasis Type="Italic">Lippia javanica</Emphasis> leaf meal

Lippia javanica leaves may have nutraceutical bioactivity and thus could be a viable alternative to antibiotic growth promoters in poultry diets. To test this hypothesis, a feeding trial was carried out to determine the effects of dietary inclusion of Lippia javanica leaf meal (LJ) on growth performance, blood parameters, carcass characteristics and meat quality of indigenous Potchefstroom Koekoek (PK) chickens. The leaf meal was used to dilute a commercial chicken grower diet at a rate of 25 or 50 g/kg diet. Two additional experimental diets, a positive control (commercial chicken grower diet with antibiotics, CON+) and a negative control (commercial chicken grower diet without antibiotics, CON–), were also formulated. Feed intake and growth performance were measured over a period of 13 weeks before slaughtering for carcass and meat quality measurements. Blood was collected in week 11 to determine haematological and serum biochemical parameters. Diet had no effect on overall FCE but significantly (P?<?0.05) affected bilirubin, alanine aminotransferase (ALT), aspartate transaminase (AST), sodium, potassium, cholesterol and magnesium levels in blood. When included at 50 g/kg, LJ increased carcass weight (P?<?0.05). Meat from CON– (6.07) and LJ50 (6.08) chickens had a higher pH than from CON+ (5.9) and LJ25 (5.8) chickens. Breast muscle in CON– chickens had higher (P?<?0.05) lightness (L*) value (53.2) compared to chickens fed on other diets. It was observed that meat from LJ25 chickens had the highest for redness value (2.3). It was concluded that L. javanica leaf meal can be included up to 50 g/kg in Potchefstroom koekoek chicken diets without causing negative effects on the birds’ feed intake, utilisation and weight gain. Diet-induced changes observed in blood parameters and meat quality fell within the expected normal ranges for indigenous chickens.     

Dietary synbiotic supplementation improves the growth performance,body antioxidant pool,serum biochemistry,meat quality,and lipid oxidative stability in broiler chickens

The present study investigated the effects of Lactobacillus acidophilus (LBA) and mannan-oligosaccharides (MOS) supplementation on the production performance, serum biochemistry, antioxidant profile, health indices, meat quality, and lipid oxidative stability of broiler chicken. A total of 252 commercial broiler chickens at 1 d old of uniform body weight were randomly allocated to 6 maize-soybean-based dietary treatments: T₁ (control diet), T₂ ( antibiotic bacitracin methylene di-salicylate [BMD] at 20 mg/kg diet), T₃ (MOS at 0.1% + LBA at 10⁶ CFU/g feed), T₄ (MOS at 0.1% + LBA at 10⁷ CFU/g feed), T₅ (MOS at 0.2% + LBA at 10⁶ CFU/g feed), and T₆ (MOS at 0.2% + LBA at 10⁷ CFU/g feed). Each treatment was assigned to 6 replicates of 7 birds. The samples for meat quality and serum biochemistry analysis were taken from 12 birds per treatment (2 birds/replicate). The results revealed better (P < 0.01) growth performance and production efficiency of birds fed either T₅ or T₆ diet compared to control or BMD supplemented diet and BMD-supplemented birds superseded the control birds. Higher (P < 0.01) serum and liver antioxidant enzyme activities, meat antioxidant capacity (2, 2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid [ABTS] and 1, 1-diphenyl-2-picrylhydrazyl [DPPH] assays], serum total protein, high-density lipoproteins (HDL) cholesterol (P < 0.05), and globulin levels (P < 0.01) were observed in birds fed either T₅ or T₆ diet compared to control or BMD supplemented birds, whereas, lower lipid oxidation (P < 0.01), cardiac risk ratio, atherogenic coefficient, atherogenic index of plasma, serum glucose, triglyceride, total cholesterol levels (P < 0.01), and serum albumin-to-globulin ratio (P < 0.05) were observed in the chickens. The pH of meat from birds fed T₄, T₅ or T₆ diet was lower (P < 0.01) compared to control and other treatments. The extract release volume (ERV), water holding capacity (WHC), and protein content of meat were higher (P < 0.05) in birds fed either T₅ or T₆ diet compared to control or BMD supplemented birds. Thus, it was concluded that the supplementation of 0.2% MOS along with LBA at 10⁶ CFU/g is optimum for better growth performance, serum biochemistry, antioxidant profile, health indices, meat quality, and lipid oxidative stability of broiler chickens.     

The effect of dietary turmeric on antioxidant properties of thigh meat in broiler chickens after slaughter

Two hundred and fifty‐day‐old male broiler chicks (Ross 308) were used to investigate the dietary supplementation effects of different levels of 0.0 turmeric rhizome powder (TRP) (free TRP, F.TRP), 0.25 (low TRP, L.TRP), 0.5 (medium TRP, M.TRP) and 0.75% TRP (high TRP, H.TRP) or 50 mg/kg vitamin E (VE) on antioxidant properties of thigh meat in broiler chickens after slaughter. No effect of treatment was observed for the activities of glutathione peroxidase (GPX) and superoxide dismutase (SOD) and total antioxidant status (TAS) in thigh meat (P > 0.05) but all were reduced over time (P < 0.0001). A significant treatment*time interaction was observed for thigh meat GPX activity (P = 0.02). Significant effects of treatment and time were observed for malondialdehyde (MDA) content (P < 0.05). There was no significant difference between the treatments for thigh meat MDA content at slaughter (P > 0.05). Three days after refrigerator storage, MDA content in thigh meat of M.TRP birds was lower than that of F.TRP birds (P < 0.05). Both the M.TRP and VE birds showed a lower MDA content in thigh meat as compared with F.TRP birds 7 days after storage (P < 0.05). In conclusion, dietary consumption of 5 mg/kg TRP can increases the thigh meat shelf‐life storage and quality in broiler chickens after slaughter.     

Polyethylene glycol as a means for reducing the impact of condensed tannins in carob pulp: effects on lamb growth performance and meat quality

We conducted an experiment to evaluate the effects that a diet containing condensed tannins with and without polyethylene glycol (PEG) has on lamb growth and meat quality. Twenty-three male Comisana lambs were introduced to the three experimental diets between 45 and 50 d of age. Eight were given a diet containing 56% of Ceratonia siliqua (carob) pulp (tannin group), another eight received the same diet with a supplement of 40 g of PEG for each kilogram of diet (PEG group), and the remaining seven lambs were given a conventional maize-based diet (maize group). Voluntary feed intake and live weights were measured until slaughter at 105 d of age, and digestibility measurements were undertaken toward the end of the feeding trial. Carcass yield, meat quality characteristics, and a taste panel evaluation were conducted. The tannin-based diet contained 2.5% condensed tannins (DM basis), and lambs given this diet had lower growth rates and poorer feed efficiencies (P < .01) compared with the other treatment groups. Daily gain was similar between the maize and PEG lambs, although the efficiency of feed conversion was highest in the maize group. The digestibility of DM, N, and fiber was reduced (P < .05) by the condensed tannins. Lambs fed the tannin diet had a lower carcass yield (P < .05) and had less fat (P < .05), and the meat had a higher ultimate pH (P < .01) than those given the PEG or maize diets. Condensed tannins affected meat color, which was lighter (L*) than meat from lambs given the PEG-containing diet (P < .01). Sensory evaluation showed that panelists preferred meat from lambs receiving PEG and maize treatments compared with those receiving the tannin diet, and this could be related to differences in meat ultimate pH and carcass fatness. These results show that condensed tannins from carob pulp are very detrimental to feed digestibility and lamb performance. Inclusion of 40 g of PEG/kg diet eliminated the effects of condensed tannins so that lamb performance and meat quality were similar to lambs given a maize-based diet.     

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.     

Physical and nutritional properties of buffalo meat finished on hay or maize silage‐based diets

The current study examines the effect of different finishing diets (hay‐ vs. maize‐silage on meal ration) on carcass quality, physical, chemical and sensory properties, and fatty acid profiles of buffalo meat. Twenty male Italian Mediterranean buffaloes (246 ± 9.00 kg live weight) were distributed at random into two groups at the beginning of the finishing period (368 ± 20 days). The buffaloes were offered two finishing diets: a maize silage (MS) or an alfalfa hay (AH) diet. No significant differences were found between dietary treatments for live and carcass weight. Meat chemical composition was influenced by dietary treatment. A higher fat content was detected in meat from animals finished with MS than AH (P < 0.05). Overall, the data indicated differences between the fatty acid profiles of meat as a consequence of different feeding systems. The higher fat deposition in the MS group resulted in meat with a less favorable fatty acid profile (i.e. a lower polyunsaturated/saturated fatty acid ratio and α‐linolenic fatty acid content) in relation to human health compared with meat from animals fed the AH diet.     

Effect of Monascus Compound Additive on Growth Performance and Meat Quality of Broiler

This trial was conducted to study the effect of Monascus compound additives on growth performance and meat quality of broilers.The total of 400 one-day-old Avian broilers were randomly allotted into 4 groups with 5 replicates per group and 20 birds per replicate.The broilers in group Ⅰ(control group),were fed a basal diet,and those in experimental groups Ⅱ,Ⅲ and Ⅳ were fed the basal diet supplemented with 0.5%,1% and 1.5% Monascus compound additives,respectively.The experiment lasted for 42 d.At the ending of the experiment,all the birds were weighted and two of each replicate were slaughtered,the samples from breast and leg muscles were taken for meat quality measurement.The results showed as follows:Compared with control group,the ADG increased significantly（P<0.05),and F/D decreased significantly（P<0.05）in group Ⅲ and Ⅳ,but the differences were not significant between group Ⅲ and Ⅳ(P>0.05);Compared with the control group,the muscle redness（a^*）and yellowness（b^*）in all the experimental groups increased significantly（P<0.05),and the drip loss rate decreased significantly（P<0.05),but the muscle lightness（L^*),cooking loss rate and shear force had no significant change（P>0.05),and pH_{24 h} of muscles in groups Ⅲ and Ⅳ reduced significantly（P<0.05).In conclusion,adding Monascus compound additives in diets could improve growth performance and meat quality in broiles, and the appropriate level should be 1%.     

Effect of dietary astaxanthin rich yeast,Phaffia rhodozyma,on meat quality of broiler chickens

We evaluated effects of dietary supplementation with astaxanthin (Ax)‐rich yeast, Phaffia rhodozyma (Xanthophyllomyces dendrorhous), on broiler chicken meat quality. Fourteen‐day‐old female Ross broilers were divided into three groups: control group, Ax‐free diet; Ax 10 group, 10 mg/kg Ax diet; and Ax 20 group, 20 mg/kg Ax diet for 28 days. At 42 days old, chickens were slaughtered, and then growth performance, meat quality and sensory attributes were analyzed. Compared with the control, a* values increased significantly after slaughter and 48 h postmortem for Ax 20 samples (P < 0.05) and for b* values in Ax 20 and Ax 10 groups (P < 0.05). Cooking loss decreased in the Ax 20 group (P < 0.05). After 120 h aging, contents of several free amino acids and total free amino acid content of Ax 20 group were significantly higher than the control (P < 0.05). In sensory evaluation, meat texture attributes improved significantly in the Ax 20 group (P < 0.01). No significant changes occurred in flavor attribute scores of meat soup from the Ax 20 group compared with the control even though most assessors preferred meat soup from the Ax 20 group. Overall, Ax‐rich yeast in the diet improves broiler chicken meat quality.     

Performance and meat quality characteristics of broilers fed fermented mixture of grated cassava roots and palm kernel cake as replacement for maize

Performance and meat quality characteristics of broilers fed fermented mixture of grated cassava roots and palm kernel cake (FCP-mix) as a replacement for maize were studied. One hundred and eighty (180), 7-day-old broiler chickens were divided into six groups of 30 birds, and each group replicated thrice. Six experimental diets were formulated for both starter and finisher stages with diets 1 and 6 as controls. Diet 1 contained maize whereas diet 6 contained a 1:1 mixture of cassava root meal (CRM) and palm kernel cake (PKC). In diets 2, 3, 4, and 5, the FCP-mix replaced maize at the rate of 25, 50, 75, and 100%, respectively. Each group was assigned to one experimental diet in a completely randomized design. The proximate compositions of the diets were evaluated. Live weight, feed intake, feed conversion ratio (FCR), carcass weight, and sensory attributes of the meats were obtained from each replicate and data obtained was analyzed statistically. The results showed that live weight, average daily weight gain (ADWG), average daily feed intake (ADFI), and FCR of birds on treatment diets were better than those on the control diets (Diets 1 and 6). The feed cost per kilogram weight gained decreased with inclusion levels of FCP-mix. Birds on diet 1 recorded significantly (p < 0.05) higher dressing percentage than those on the other five treatments. The sensory attributes of the chicken meats were not significantly (p > 0.05) affected by the inclusion of FCP-mix in the diets. FCP-mix is a suitable substitute for maize in broiler diet at a replacement level of up to 100% for best live weight, carcass weight yield, and meat quality.     

Effects of Early Feed Restriction on Performance and Ascites Development in Broiler Chickens Subsequently Raised at Low Ambient Temperature

The objective of this study was to examine the effectiveness of early-age growth limitation, achieved through feed restriction (FR), as a means of reducing ascites mortality in broiler chickens exposed to low ambient temperatures. Feed restriction was applied to broilers from 5 to 11 d of age so as to reduce their weight gain to about 40% of that of control broilers that were fed ad libitum (AL). At the age of 21 d the chickens were exposed to a temperature of 15°C, which induced ascites. By 46 d of age, ascites incidence and mortality in the feed-restricted birds were reduced to 15.79 vs. 36.84% and 7.89 vs. 26.32%, respectively, compared with those in the controls (P < 0.05). After feed restriction was stopped, the FR chickens had accelerated weight gain and improved feed conversion ratio from 11 to 18 d of age (P < 0.05), and by 46 d they had achieved the same body weight as the AL birds. Ascitic broilers had smaller relative breast muscle and spleen weights than those of the healthy broilers at 46 d (P < 0.05). However, the relative weights of lung, heart, and liver and the right ventricle weight per total ventricle weight (RV:TV) ratios were greater in ascitic broilers (P < 0.05). At age 37 d, when ascites had developed but not yet caused mortality, the ascitic broilers had lower plasma concentrations of the thyroid hormones thyroxine and triiodothyronine, and higher hematocrit values (P < 0.05) in comparison with the healthy ones. Ascitic birds also had lower oxygen consumption at 6 wk (P < 0.05), which agrees with information that the terminal stage of the ascites syndrome can be characterized by low oxygen consumption. We concluded that the early-age feed restriction reduced ascites incidence and mortality and prevented reduction of the thyroid hormone concentrations in male broilers reared at low ambient temperature from the age of 3 wk onward.     

Free range and deep litter poultry production systems: effect on performance, carcass yield and meat composition of cockerel chickens

This study was carried out on 150 cockerel chickens each of Harco Black and Novogen strains to determine their performance, carcass yield and meat composition on free range and deep litter production systems. The birds were brooded for 4 weeks and thereafter allotted to the different production systems for a period of 12 weeks. Each production system was allotted 150 chicks (75 chicks per strain) with three replicates of 25 chicks. The birds on deep litter production system were fed ad libitum while each bird on free range was fed 50 % of its daily feed requirement. On the 84th day, a total of 36 birds were randomly selected for analysis of the carcass yield and meat composition. The data generated were subjected to a two-way analysis of variance in a 2?×?2 factorial experimental arrangement. Novogen strain consumed less feed (P?<?0.05) on free range and had the best feed/gain (2.72). A higher (P?<?0.05) shear force value (3.74 N) was obtained in the thigh muscle for birds on free range. The tibia proximal length and breadth, and tibia distal length and breadth were significantly (P?<?0.05) affected by the production systems and strains. On free range, Harco black had more meat (85.69 g) than bone (18.07 g) in the breast while Novogen had the lowest meat/bone (2.38). Conclusively, Novogen strain should be raised on free range for a better performance in terms of feed/gain, but for higher meat composition, Harco black is a better strain.     

Effects of rearing systems on growth performance,carcass yield,meat quality,lymphoid organ indices,and serum biochemistry of Wannan Yellow chickens

This study was conducted to investigate the effects of free‐range system (FRS) and conventional cage‐rearing system (CRS) on growth performance, carcass yield, meat quality, lymphoid organ indices, and serum biochemistry of Wannan Yellow chickens. At 56 days of age, a total of 640 male chickens were randomly allocated to FRS and CRS groups, each of which included 4 replicates with 80 chickens in each replicate. The experiment lasted from 56 to 112 days of age. The results showed that CRS chickens exhibited better final body weight, average daily feed intake, average daily gain, and feed conversion ratio, whereas FRS chickens showed better breast and leg yields, shear force, meat color, lower drip loss, and decreased abdominal fat deposition. Moreover, the absolute thymus weight and thymus to body weight ratio of FRS birds were significantly higher than those of CRS birds (p < 0.05). Additionally, FRS chickens had significantly reduced glucose, total protein, triglyceride, and cholesterol contents, but enhanced levels of high‐density lipoprotein cholesterol (p < 0.05). In conclusion, the FRS has advantages in breast and leg yields, meat quality, and some serum biochemical parameters of Wannan Yellow chickens, whereas it has negative effects on growth performance.     

Dietary supplementation of phenyllactic acid on growth performance,immune response,cecal microbial population,and meat quality attributes of broiler chickens

A total of 750 one-day-old male broiler chicks were randomly fed 5 dietary treatments with 5 replicate pens per treatment. The 5 dietary treatments fed for 42 d were a corn-soybean meal basal diet without antibiotic (control); a mixture of 10 ppm of avilamycin + 60 ppm of salinomycin as antibiotic growth promoters (AGP); 0.1% phenyllactic acid (PLA); 0.2% PLA; and 0.4% PLA. The BW gain and FE were significantly improved in AGP and PLA groups compared with control group. The white blood cells and heterophil counts were significantly higher in the PLA-supplemented groups compared with AGP and control groups, but the heterophil-to-lymphocyte ratio was lower in the control group than other groups. The plasma IgY concentration was significantly increased in birds fed PLA-supplemented diets, but the plasma IgA and IgM concentrations were not different among the treatment groups. In addition, the antibody titer against Newcastle disease virus was significantly higher in PLA-treated compared with control and AGP-treated groups. Neither PLA nor AGP treatments affected the cecal aerobes andSalmonella content; however, cecalLactobacillus population increased in chickens fed 0.1% PLA, and total coliform bacteria population significantly decreased in chickens fed various levels of PLA and AGP. Dietary supplementation of PLA did not affect the pH, lightness, and redness of breast meat, but the water-holding capacity and shear force value increased and the yellowness decreased significantly when birds were fed PLA. It was concluded that dietary supplementation of 0.1 and 0.2% PLA improves BW gain and FE of broiler chickens. In addition, PLA supplementation increases the immune characteristics and the number of lactic acid bacteria, decreases the number of coliform bacteria, and improves the meat quality attributes of broiler chickens. Thus, dietary PLA could be a viable alternative to antibiotics in broiler diets.