Female Broiler Chickens Research Articles

Effect of Level and Type of Mushroom on Performance, Blood Parameters and Natural Coccidiosis Infection in Floor-Reared Broilers

An experiment was conducted to evaluate the feeding of four medicinal mushrooms via fungus myceliated grain (FMG) at three levels on production performance, blood parameters and natural coccidiosis oocyst excretion in floor reared broiler chickens. Three hundred day-old female broiler chickens were weighed and randomly assigned to nine different treatment groups. Each group was replicated three times with 10 birds per replicate pen. The four mushrooms utilized were Shiitake (Lentinus edodes), Reishi (Ganoderma lucidum), Oyster (Pleurotus ostreatus) and Cordyceps (Cordycepss inensis). Each mushroom was supplemented at a 5 and 10% inclusion level into a basal meal ration, and compared to a control ration containing no mushrooms. Body weights were assessed on days 28 and 49. Bursa weights, Eimeria oocyst counts, blood differential percentages and mortality rates were measured at 49 days of age. Eimeria oocyst counts, blood differential percentages and both bursa and body weights differed significantly (P ≤ 0.05) between treatment groups. Treatment 8 (Oyster 5%) produced the highest average body weight at 3.21 kg, while treatment 5 (Cordyceps 10%) produced the lowest at 2.33 kg. A higher oocyst count and increased heterophil percentage was observed in treatment 6 (Reishi 5%). There were some basic trends in the patterns of heterophil and lymphocyte percentage elevation in treatment 3 (Shiitake 10%). The results from this experiment demonstrate the ability of certain mushrooms to influence body weight of broiler chickens and show some immune enhancement via the bursa of Fabricius.

Dietary biotin supplementation does not alleviate the development of footpad dermatitis in broiler chickens

SUMMARY The effects of 4 levels of supplemental dietary biotin (0.05, 0.1, 0.2, 0.4 mg/kg) on live performance, and the incidence and severity of footpad dermatitis (FPD) were investigated in 2 experiments. In experiment 1, 600 one-day-old female broiler chicks were randomly distributed among 40 pens. Ten replicate pens were allotted to each of the 4 treatments, with 15 broilers per pen. In experiment 2, 1,440 one-day-old mixed-sex chicks were placed in 32 pens (45 chicks per pen), with 8 replications per treatment. Pen BW and feed consumption were measured at 21, 42, and 56 d of age in experiment 1 and at 15, 29, 43, and 57 d of age in experiment 2. Mortality was recorded twice daily and weighed to calculate the adjusted FCR in both experiments. In addition to live performance, FPD incidence and severity were evaluated at each of these time periods using a 3-point scale to document the progression of severity of lesions over time. Litter samples were also collected, pooled, and analyzed for moisture on d 1 and 57 in experiment 2. The live performance of broilers did not vary in experiment 2. Moreover, neither incidence nor severity of FPD was affected by dietary biotin supplementation. Litter moisture did not vary in experiment 2, but equaled or exceeded 35% in all treatments by d 57. No dietary biotin supplementation level resulted in the alleviation of FPD. It was concluded, based on these results, that dietary biotin supplementation is not an effective tool in preventing the development of FPD in broiler chickens.

Requirement of available phosphorus by female broiler chickens keeping the calcium:available phosphorus ratio at 2:1

Four trials were conducted to determine the requirements of available phosphorus (aP) of female broiler chicks from 1 to 10 (exp.1), 11 to 21 (exp.2), 22 to 33 (exp.3), and from 34 to 46 (exp.4) days of age, keeping the calcium:available phosphorus ratio equal to 2:1. In each trial, 480 Cobb broilers were randomly allotted in a completely randomized design with 6 treatments, 8 replicates and 10 birds per pen. The levels of aP ranged from 2.0 to 5.5 g/kg (Exp. 1), 1.9 to 5.4g/kg (exp. 2), 1.8 to 5.3 g/kg (exp. 3) and 1.7 to 5.2 g/kg of diet (exp. 4), in increments of 0.7 g/kg. The experimental diets were formulated using corn and soybean meal and the available phosphorus was considered 33% of total phosphorus. The characteristics evaluated were body weight gain, feed intake, feed conversion ratio and bone parameters. For female broiler chicks from 1 to 10; 11 to 21; 22 to 33; and from 34 to 46 days of age, the levels of available phosphorus and calcium recommended are 4.59 and 9.18; 3.88 and 7.76; 3.58 and 7.16; and 2.56 and 5.12 g/kg of diet, respectively.

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.

The effects of early‐age thermal manipulation and daily short‐term fasting on performance and body temperatures in broiler exposed to heat stress

This study was conducted to investigate the effects of thermal manipulation at 5 days of age and short-term fasting during the warmest part of the day on responses to prolonged heat stress of broilers. A total of 240-day-old Ross 308 female broiler chicks were divided into three groups: control, thermal manipulation (chicks were exposed to 36 °C for 24 h at 5 days of age) and short-term fasting during the warmest part of the day (10.00-17.00 h). Prolonged heat stress was induced daily from 28 to 42 days by heating until the ambient temperature reached 32-35 °C between 10.00 and 17.00 h. Both thermal manipulation and short-term fasting resulted in a decrease in rectal temperatures and haematocrit values at 35 and 41 days of age. Thermal manipulation improved body weight, feed consumption and feed conversion. However, short-term fasting caused a reduction in body weight and a deterioration in feed conversion. Short-term fasting lowered the percentages of carcass, whereas thermal manipulation highered breast yield. Both thermal manipulation and short-term fasting decreased heart mass and abdominal fat.

Effects of breed and dietary nutrient density on the growth performance, blood metabolite, and genes expression of target of rapamycin (TOR) signalling pathway of female broiler chickens

This study was conducted to compare the effects of exchanged diets with identical energy level on characteristics of slow-growing (WENs Yellow-Feathered Chicken, WYFC) and fast-growing (White Recessive Rock Chicken, WRRC) female chickens. A total of 1450 WYFC and 1150 WRRC 1-day-old female hatchlings were used. A high-nutrient-density (HND) diet and a low-nutrient-density (LND) diet were formulated for three phases. A completely randomized experimental design with a 2 × 2 factorial arrangement (diet and breed), each with five replicates of 145 and 115 birds, was applied. The results showed that WRRC had a higher body weight (BW), average daily feed intake and average daily gain than WYFC throughout the experiment (p<.05). WYFC that were provided with HND groups had a higher BW only in the starter and grower phases, whereas WRRC had a higher BW in the HND group than in LND groups throughout the experiment. The feed:gain ratio and protein efficiency ratio (PER) were better for WRRC in the starter and grower phases; however, these ratios were better for WYFC in the finisher period. The LND groups had a higher PER throughout the experiment for both breeds (p<0.05). The breast and leg muscle weights were higher for WRRC compared with WYFC during the grower and finisher phases (p<0.05). WRRC had a lower liver index but higher serum UA and alkaline phosphatase (ALP) concentrations than WYFC (p<0.05). No diet effect was observed on organ indices, muscle yields or blood responses. The gene expressions of Rheb, TOR, S6K1 and 4E-BP1 in gastrocnemius muscle were the highest in the WYFC-LND groups at 63 and 105 days (p<0.05). These findings suggested that different genotypes respond differently to changes in dietary nutrient density and that lower-nutrient-density diets are optimal for the long-term housing of broiler chickens.

Reevaluation of digestible amino acid requirements of male and female broilers based on different ideal amino acids ratios in starter period

An experiment was conducted to reevaluate the digestible amino acid (AA) requirements of broilers based on different ideal amino acid ratios for male and female broiler chicks during the starter period (1–14 days). A total of 720 one-day-old feather sexed male and female broiler chicks were equally distributed to 12 dietary treatments with 4 replications per treatment and 15 chicks per replication. AA requirements were estimated based on digestible Lys requirement of 1.22 and 1.20 percent for male and female respectively, and different ideal AA ratios including Illinois Ideal Chick Protein (IICP), CVB, Feedstuff, NRC, ROSS and RPAN (Rhone Poulenc Animal Nutrition). Feed intake, body weight gain (BWG), and humeral immunity responses were measured for each pen at day 14 post hatch and feed:gain was calculated. Results of this study show that broiler chicks fed IICP diet had lower feed intake while broiler chicks fed ROSS and RPAN diets had lower BWG and feed:gain compared to other ideal amino acid profiles. When comparisons were made among chicks fed diets formulated with different ideal amino acid ratios, the most significant (p<0.05) performance improvements were observed by Feedstuff and CVB ratios. Feedstuff ratio had highest body weight gain and a better feed:gain (p<0.05) relative to all the other ratios for both genders. Digestible Lys, Met, Met+Cys, Thr, Ile, Arg, Trp, Leu and Val requirements for male and female broiler were estimated based on Feedstuff ratio to be 1.22, 0.54, 0.85, 0.73, 0.85, 1.34, 0.24, 1.62, 0.93 and 1.20, 0.53, 0.84, 0.72, 0.83, 1.32, 0.24, 1.60, 0.92 in starter period, respectively.

Attitudes Toward Risk and Coping Responses: The Case of Food Crop Farmers at Agona Duakwa in Agona East District of Ghana

The effect of fermentation duration of raw Bambara groundnut ( Voandzeia subterranean (L) on the growth performance, carcass quality and feed cost of finisher broilers were investigated. Two hundred 21 day old female Arbor acre broiler chicks were randomly divided into five treatment groups of forty birds each. The experimental design was a Completely Randomized Design with each treatment replicated five times with eight birds per replicated. Five test diets were formulated to contain no Bambara groundnut (C0) control or 15% of Bambara groundnut (BGN) either socked in water for 12 hours (F0) or socked and fermented for 12 hours, (F12), 24 hours (F24) and 36 hours (F36). Results showed that total feed consumption was significantly (P<0.05) higher with birds fed diet F0 compared with birds fed diet F12. The final body weight and total body weight gain were significantly (P<0.05) higher for the control diet (C0) compared to the rest of the treatments. Birds fed the control diet (C0) had improved fed conversion ratio (P<0.05) compared with the other treatments. Bigger liver and heart (P<0.05) were obtained with birds fed diet containing BGN (F0, F24 and F36) compared with the control (C0) and F12 group. The cost per kg weight gain ($1 USA = CFA 480 Francs) was significantly (P<0.05) lower with birds fed diet F0 compared with birds fed diet F12, F24 and F36 but comparable with the control (Co) diet. The result of the present study showed that fermentation duration had no significant effect on body live weight, weight gain and feed consumption ratio.

Electrical waterbath stunning: Influence of different waveform and voltage settings on the induction of unconsciousness and death in male and female broiler chickens

Stunning effectiveness of male and female broiler chickens was analyzed in response to different waveforms at 3 constant voltage levels. In total, 180 male and female broiler chickens were stunned using a sine wave alternating current (AC) of 50 Hz, rectangular AC of 70 Hz, and pulsed direct current (DC) of 70 Hz (duty-cycle 1:1) with a constant voltage of 60, 80, or 120 V, respectively. In each stunning group, 10 male and 10 female birds were stunned for 4 s. The current obtained by every bird was recorded. For stunning efficiency, the electroencephalogram (EEG) and physical reflexes were recorded and analyzed. The EEG was recorded for 120 s poststun. Simultaneously, the occurrence of spontaneous eye blinking, wing flapping, and breathing was assessed, and the corneal reflex was tested every 20 s poststun. The EEG was analyzed regarding the occurrence of a profound suppression to less than 10% of the prestun level in the 2 to 30 Hz and 13 to 30 Hz bands. Female broilers obtained a significantly lower stunning current compared with that of the males. This resulted in a lower stunning efficiency for females, when the same constant voltage was applied to males and females. The waveforms required different amounts of currents to achieve a 90% stunning efficiency. A minimum necessary stunning current of 70, 90, and 130 mA could be established for sine wave AC, rectangular AC, and pulsed DC, respectively. The low stunning efficiency of pulsed DC might be caused by the short stunning time of 4 s. This effect should be further investigated for DC stunning. Very few birds stunned with AC resumed breathing following stunning, indicating stun to kill. Pulsed DC stunning showed a lower effect on the induction of death. The level of wing flapping, indicating convulsions and possible meat quality defects, was higher for the AC treatments.

Effect of dietary zinc proteinate supplementation on growth performance, and skin and meat quality of male and female broiler chicks

1. An experiment was conducted to evaluate the effect of dietary zinc proteinate (ZP) supplementation on growth performance and on skin and meat quality of male and female broiler chicks. 2. A total of 240 1-d-old male and 240 1-d-old female broiler chicks were randomly distributed into 24 floor pens (12 replicate pens/sex; 20 birds/pen) and were given either 0 (Control diet) or 40 mg/kg ZP (ZP 40), resulting in a 2 × 2 factorial arrangement of treatments. 3. The growth performance of male and female broiler chicks was not affected by the ZP supplementation, but the males showed significantly higher growth performance than did females. 4. ZP supplementation increased the total thickness of skin in both sexes, and males had thicker skin than females. It also increased the collagen content of skin, but not that of meat. Males had higher skin collagen contents than did females, but no sex difference was found in the meat collagen contents. 5. ZP supplementation did not affect the shear force values of skin and meat; however, males had higher shear force values of back skin than females. ZP supplementation increased the zinc contents of thigh meat and plasma in both sexes. Males had higher zinc contents in back skin than females. 6. It is concluded that dietary ZP supplementation could increase the skin quality of broiler chicks in both sexes, particularly in female broilers, without any effect on growth performance. Male broilers have better growth performance and skin quality than females.

Alleviative effects of α-lipoic acid supplementation on acute heat stress-induced thermal panting and the level of plasma nonesterified fatty acids in hypothyroid broiler chickens

1. The present study was conducted to examine the effects of α-lipoic acid on hypothyroidism-induced negative growth performance and whether α-lipoic acid alleviates acute heat stress in relation to hypothyroid status. 2. Female broiler chickens (14 d-old) were fed diets supplemented with α-lipoic acid (100 mg/kg) and an antithyroid substance, propylthiouracil (200 mg/kg), for 20 d under thermoneutral conditions (25°C). At 42 d of age, chickens were exposed to a high ambient temperature (36°C, 60% RH) for 4 h. 3. Under the thermoneutral condition, propylthiouracil administration decreased feed efficiency and concomitantly increased adipose tissue and thyroid gland weights. Plasma nonesterified fatty acids and triacylglycerol were also increased by propylthiouracil administration. However, α-lipoic acid supplementation did not affect the hypothyroidism-induced effects. 4. In hypothyroid chickens, the rise in respiratory rate induced by heat exposure was greatly inhibited by α-lipoic acid administration at 1 h, but this effect had disappeared at 4 h. In addition, a similar inhibitory effect on the concentrations of plasma nonesterified fatty acids was subsequently observed at 4 h. 5. Therefore, the present study suggested that α-lipoic acid alleviates acute heat stress if chickens are in a hypothyroid status.

Productive performance and histological features of intestinal mucosa of broiler chickens fed different dietary protein levels

To evaluate the effect of decreasing dietary protein on growth performance, carcass traits, and intestinal mucosal morphometry, 180 female Hubbard strain broiler chickens were divided into 3 groups and fed 3 isoenergetic diets ad libitum from 14 d of age until slaughter age (49 d). The treatments varied according to 3 protein levels: high-protein diet (HiP, 22.5% CP, DM basis), medium-protein diet (MedP, 20.5% CP), and low-protein diet (LowP, 18.5%). Diets were obtained by replacing wheat middlings with soybean meal and were formulated to meet or exceed broiler amino acid requirements of the NRC. Morphometric indices of duodenum, jejunum, and ileum were measured at the end of the feeding period and included villus height, crypt depth, villus-to-crypt ratio, and apparent villus surface area. The dietary protein level had a significant effect on final BW of birds, whereas ADG, ADFI, and feed efficiency remained unaffected by dietary treatment. The muscle (breast and drumstick) yields were significantly higher in birds fed the HiP diet compared with those of the MedP and LowP diets. Meat quality traits were not affected by the protein level. The villus surface area of all intestinal segments did not change among groups. Instead, reducing the dietary protein level to 20.5% resulted in a higher villus height and villus height to crypt depth ratio in the duodenum and ileum. On the basis of our findings, even if the high-protein diet promoted meat yield, a medium-protein diet could positively support broiler growth performance, as confirmed by favorable morphometric features of the intestine.

Effect of Sex and Dietary Organic Zinc on Growth Performance, Carcass Traits, Tissue Mineral Content, and Blood Parameters of Broiler Chickens

Zinc (Zn) is an essential mineral for animal development and function. A study was carried out to evaluate the effect of sex and dietary organic zinc (OZ) on growth performance, carcass traits, tissue mineral content, and blood parameters of broiler chickens. A total of 240 1-day-old male and 240 female broiler chicks (Cobb × Cobb) were assigned to two dietary levels of OZ (2 × 2 factorial) with six replicates per treatment (20 birds/replicate pen). The OZ supplementation levels were 0 and 25 ppm. Results showed that OZ supplementation did not affect the growth performance of male and female broilers, but the males showed significantly better (P < 0.05) growth performance than females did. Similarly, OZ supplementation did not affect the thickness of both the back and thigh skin of male and female broilers; however, males had thicker skin than females. Dietary OZ supplementation did not affect collagen contents in the skin and meat samples. Male broilers had higher skin collagen contents than females, but no sex difference was found in meat collagen contents. OZ supplementation did not affect the shear force values of skin and meat samples. Male broilers had higher shear force values of back skin than females, but not in the meat samples. Dietary OZ supplementation increased (P < 0.05) the thigh meat Zn content in both sexes. The plasma Ca content was significantly (P < 0.05) increased by dietary OZ supplementation; however, other blood parameters were not affected by dietary OZ supplementation. Males had higher plasma glucose and cholesterol content than females. It is concluded that dietary OZ supplementation at the level of 25 ppm does not affect the growth performance and skin quality of broiler chickens but increases the Zn content in thigh meat and Ca content in plasma of broiler chickens. Male broilers had better growth performance and skin quality than females.

Effects of l-carnitine via in ovo injection with or without l-carnitine feed supplementation on broiler hatchability and posthatch performance

SUMMARY On d 18 of incubation, Ross × Ross 708 eggs were injected immediately before transfer with supplemental l -carnitine at concentrations of 8, 16, or 32 mg/100 µL by using an automated multiegg injector. Three control groups (noninjected and injected with or without diluent) were also included. After hatching, 1,080 male and female broiler chicks were distributed into 90 pens of an experimental broiler house. Chicks hatched from eggs that were injected with l -carnitine at each of the 3 dosages received feed that was or was not supplemented with 50 ppm of l -carnitine, with the total number of treatments increased to 9 with 10 replicate pens per treatment during the grow-out phase of the experiment. None of the treatments had any effect on the incubation time or hatchability of fertilized eggs. At the end of the grow-out phase, birds that were fed supplemental l -carnitine and that had been injected with l -carnitine in ovo had lower BW and ate less feed. However, these same birds also exhibited a reduction in feed conversion when compared with birds that did not receive supplemental dietary l -carnitine. Livability was not affected at hatch or at 21 and 45 d posthatch by any of the experimental treatments. At processing, absolute and relative weights of the carcass, back half, and abdominal fat were found to be unaffected by any of the treatments. Breast meat yield was unaffected, but the absolute breast meat weight was reduced in birds given l -carnitine in ovo and in the feed. On the basis of the responses in feed consumption, final BW, and breast meat weight, supplementation of broiler diets with 50 ppm of l -carnitine appeared to reach toxic levels when provided with 8, 16, or 32 mg/100 µL of l -carnitine administered via in ovo injection.

Microcomputed tomographic evaluation of vertebral microarchitecture in pinealectomized scoliosis chickens

Pinealectomy was used to induce scoliosis in Broiler chickens, and the bone microarchitecture of the concave and convex sides in pinealectomized scoliosis chickens was assessed by microcomputed tomography (micro-CT). Few studies have assessed the vertebrae bone microarchitecture of the concave and convex sides in scoliosis although the curvature of the coronal plane is the main deformity in scoliosis. The purpose of this study was to determine whether there are differences in the bone microarchitecture of the concave and convex sides in pinealectomized scoliosis chickens by the technique of micro-CT. The etiology and the pathogenesis of the idiopathic scoliosis remain unclear. Limited information is available on the microarchitecture of vertebrae bone of the concave and convex sides of scoliosis, especially in the earlier stage in scoliosis development. One hundred female Broiler chickens were divided into three groups as follows: the control group (n=20), the sham operation group (n=20), and the pinealectomy group (n=60). Then the pinealectomy group was divided into three groups according to the time of killing the chickens: 1-week after the operation (group P-1 w, n=20), 2 weeks after the operation (group P-2 w, n=20), and 3 weeks after the operation (group P-3 w, n=20), respectively. Posteroanterior radiographs of the spine were taken to detect spinal curvature. Using micro-CT, the bone volume/tissue volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular separation of the concave and convex sides of the apex vertebrae in the scoliotic chickens were determined. Independent t-tests were used to assess differences of bone parameter of the concave and convex sides in each pinealectomized group. The incidences of scoliosis in the pinealectomized Broiler chickens were 84.2% (group P-1 w), 88.9% (group P-2 w), and 89.5% (group P-3 w), respectively. In groups P-1 w and P-2 w, there were no differences between the concave and convex trabecular bone microarchitectures. In group 3 w, the BV/TV, Tb.Th, and Tb.N of the concave side were significantly greater than those of the convex side. In the earlier stage of pinealectomized scoliosis chickens, there are no histological evidence of a metabolic abnormality. The greater BV/TV, Tb.Th, and Tb.N of the concave side in group P-3 w may be consistent with Wolff's law and are the secondary response to the scoliotic deformity.

Supplementation of graded levels of organic zinc in the diets of female broilers: effects on performance and carcase quality

1. Zinc is an essential trace element. The objective of this research was to investigate the effects of various levels of organic zinc (OZ) supplementation on growth performance and carcase quality of female broiler chickens. 2. A total of 3200 1-d-old female broiler chicks were randomly allotted to 16 floor pens with 200 birds per pen. A maize-wheat-soyabean meal basal diet (Control) was formulated and 20 mg/kg OZ (20 OZ), 40 mg/kg OZ (40 OZ), and 80 mg/kg OZ (80 OZ) were added to the basal diet to form 4 dietary treatments with 4 replicates per treatment. The OZ source was zinc proteinate which contained 15% zinc. 3. Results showed no significant difference between the treatments in growth performance. A significant increase in thigh skin epidermis and dermis thickness was shown in the OZ supplementation groups; however, no effect was found on the thickness of back skin epidermis and dermis. 4. Collagen contents in breast and thigh meats were not influenced by OZ supplementation but a significant increase in collagen content was found in the back and thigh skin. This increase in collagen content was significantly greater in the back and thigh skin of OZ 80 than with OZ 20. 5. Shear force value and zinc concentration in skins and meat were not significantly influenced by supplementation with OZ. 6. It is concluded that dietary OZ does not improve growth performance of broilers; however, it could increase skin thickness by increasing collagen content in skin, thereby improving carcase quality.

Effects of nonantibiotic feed additives on performance, nutrient retention, gut pH, and intestinal morphology of broilers fed different levels of energy

SUMMARY An experiment was conducted to determine the effects of different feed additives on performance, nutrient retention, gut pH, and intestinal morphology of broilers fed different levels of energy. This study was a 4 × 2 factorial arrangement of 4 feed additive programs (a basal diet without any feed additive as the control, the basal diet with added organic acid, the basal diet with added prebiotic, and the basal diet with added probiotic) with recommended levels (3,150 and 3,200 kcal of ME/kg of diet for the starter and finisher diets, respectively) or low levels (90% of recommended) of energy. A total of 640 one-day-old male and female broiler chicks were randomly assigned to 8 treatments. Each treatment consisted of 4 replicate floor pens of 20 birds each. Starter and finisher diets were fed from 1 to 21 d and 21 to 42 d of age, respectively. Dietary levels of other nutrients, housing, and general management practices were similar for all treatments. Dietary inclusion of additives had no significant effects on broiler performance, intestinal villus height, crypt depth, gut pH, and dietary AME. Birds fed the low-energy diets were heavier but had inferior FCR compared with those fed the recommended-energy diets. Prebiotic and organic acid significantly (P < 0.05) improved protein digestibility. The recommended-energy diets significantly (P < 0.05) increased AME and protein digestibility. No interactions were observed for the measured parameters.

Influence of Various Levels of Organic Zinc on the Live Performance, Meat Quality Attributes, and Sensory Properties of Broiler Chickens

The influence of supplementing diets with various levels of organic zinc (OZ) on the performance, meat quality attributes,and sensory properties of broiler chickens was investigated. A total of 3,200 1-d-old female broiler chicks were randomlyallotted to 16 floor pens (replicates) with 200 birds per pen. A corn-wheat-soybean meal basal diet (control) was formulatedand 20 ppm OZ (20 OZ), 40 ppm OZ (40 OZ), or 80 ppm OZ (80 OZ) was added to the basal diet to form four dietarytreatments with four replicates per treatment. Live performance of broiler chickens, meat quality, and sensory propertieswere evaluated. The results showed no significant difference among the treatments for live performance of broiler chickens.Significant increases ( p<0.05) in thigh skin epidermis and dermis thickness were shown in the OZ supplementation groups;however, no effect of OZ on the thickness of back skin epidermis or dermis was found. Dietary OZ levels did not affect thepH of breast and thigh meat or the water holding capacity (WHC) of thigh meat, but the WHC of breast meat increasedsignificantly (p<0.05) when birds were fed 40 OZ and 80 OZ. Results of a sensory analysis showed no differences amongthe dietary treatments. In conclusion, dietary OZ did not affect live performance or sensory properties of broiler chickensbut did increase the WHC of breast meat and thickness of skin layers; thus, improving carcass quality in broiler chickens. Key words: organic zinc, live performance, meat quality attributes, sensory properties, broilers

Herbs, thyme essential oil and condensed tannin extracts as dietary supplements for broilers, and their effects on performance, digestibility, volatile fatty acids and organoleptic properties

1. Herbs, thyme essential oil (EO) and condensed tannin (CT) extracts were compared for their effects, as dietary supplements, on broiler growth performance, nutrient digestibility and volatile fatty acid (VFA) profiles in the gut. Cooked meat from the birds fed on diets with 4 herbs and an EO extract was compared by a taste panel against those fed on the control treatment, for organoleptic properties in the meat. 2. Female broiler chicks were fed on wheat-soybean meal diets from 0–42 d of age. These chicks were given either the basal diet (control), or the basal diet with one of rosemary, garlic or yarrow herbs, mimosa, cranberry or grapeseed CT's, or thyme EO supplements (8 treatments in total). Body weight (BW) and feed consumption (FC) were measured. 3. The garlic supplement tended to improve growth rate over the first 7 d, while mimosa CT and thyme EO supplements reduced weight gains. The mimosa supplement in diets significantly reduced FC to d 21. Meanwhile, the addition of a cranberry supplement reduced the digestibility of DM, OM and N, compared with the controls. Dietary thyme EO, yarrow, rosemary and garlic supplements modified caecal isovaleric and isobutyric acid proportions (presented as ‘Other VFA’; p < 0.05). Dietary herb significantly affected the intensity of meat flavour, and the potential of observing both garlic and abnormal flavours. There were large differences between the consumption of red and white meat samples, while meat temperature affected several flavour attributes. 4. Broiler performance and digestibility for birds given dietary garlic and grapeseed CT supplements were similar to the controls, and these supplements appear suitable for dietary inclusion. Careful choices are necessary when selecting dietary plant extract supplements for broilers, but beneficial effects can be observed.

CARCASS QUALITY OF BROILER CHICKENS OF TWO HYBRID LINE SLAUGHTERED IN DIFFERENT AGE

The evaluation of carcass quality of broiler chickens is a very important segment in production, manufacture and marketing of poultry products, which depends of many factors. The aim of this experiment was to determine some criterions of carcass quality (carcass mass, dressing percentage and their variances) of fattening chickens in dependence on the following factors: hybrid, sex, age and mixture composition. Forty male and forty female chickens of two hybrid lines Cobb 500 and Hubbard Classic at the fifth, sixth and seventh weeks of age were selected for slaughter by the random selection method. Chickens were fed with two different mixtures which contented different level of protein and energy and different values of the E : P rate. The dressing percentage was represented by three kinds of dressings: basic or traditional dressing, “ready for roasting” and “ready for grilling”. The obtained results showed statistically significant (P < 0.05) influence of age and sex on the carcass mass. Namely, the broiler chickens slaughtered at the seventh age of week as well as the male chickens had the biggest carcass mass in all kind of dressing. The factor age had statistically significant (P < 0.05) influence on the dressing percentage in general, while the factor hybrid had a significant (P < 0.05) influence only on the dressing “ready for grilling”. Female broiler chickens in comparison with male chickens had a better dressing percentage at all kinds of dressing, but those differences were not statistically significant. Differences in carcass mass and dressing percentage under the influence of mixture composition were almost insignificant.