Growth and sensory characteristics of organically reared broilers differing in strain,sex and age at slaughter

Abstract

The effects of strain, sex and age on live weight, slaughter weight and sensory characteristics of organically reared broilers in orchards are presented. A total of 450 broilers of three different strains (I 657, Light Sussex, New Hampshire) were reared in an organic research orchard. Half of each strain was slaughtered at 91 days and the other half at 120 days. All broilers were weighed and a clinical welfare assessment was made at slaughter. A trained sensory panel evaluated the breast meat in relation to flavour, smell and texture characteristics defined by the panel. At both 91 and 120 days of age the commercial breed I 657 was significantly heavier than the slower growing strains. Males were significantly heavier than the females across strains. Weight ratios between males and females were nearly the same at both slaughter ages in I 657, whereas weight ratios increased significantly at 120 days in Light Sussex and New Hampshire. No overall effect of strain was found on the flavour and smell of the breast meat. However, the age-related changes in tenderness and toughness differed significantly between strains, since the commercial strain tended towards a tougher and less tender consistency with age, whereas the opposite was the case for the slower growing pure breeds. The positive flavour of salt was significantly improved at 120 days across strains with females having a saltier flavour than the males with age. The positive flavour of sweet corn was improved in the meat from the males, whereas the positive smell of sweet corn was significantly improved in both males and females. No negative effects of age were found.

In conclusion, broilers were tastier when slaughtered at 120 days compared with 91 days. The development in meat tenderness was related to strain, and weights at slaughter were related to both strain and sex.     

口服利福昔明片对 AA 肉仔鸡肠道正常菌群的影响

考察利福昔明片对AA肉仔鸡肠道正常菌群的影响,为其在兽医临床上推广应用提供科学依据。选用10日龄健康 AA 肉鸡,分别以25、50、100 mg／kg 经口灌服利福昔明片,连续用药3 d,并于首次用药后第4、7、10天处死仔鸡,取盲肠和回肠内容物进行乳酸杆菌和大肠埃希菌的选择性培养并计数,以此评价利福昔明片对肉仔鸡肠道菌群数量的影响。结果显示,利福昔明片高、中、低剂量组对回肠和盲肠的大肠埃希菌菌群数目与空白对照组相比数量减少,其中100 mg／kg 剂量组在首次用药后第4 天对盲肠大肠埃希菌影响差异显著,其他各剂量组无显著差异。利福昔明片高、中、低剂量组对回肠和盲肠的乳酸杆菌与空白对照组相比数量增加,但差异不显著。结果表明,利福昔明片对肠道内乳酸杆菌等益生菌没有影响,但能降低肠道内大肠埃希菌的数量。     

Rate of metabolic decarboxylation of leucine as assessed by a l[1-(13)C(1)]leucine breath test combined with indirect calorimetry of broiler chickens fed isocaloric diets with different protein:fat ratio

Research has shown that broiler chickens reared on a low-protein diet have a more efficient protein digestion. However, information on the fate of absorbed amino acids in relation to the dietary crude protein level in poultry is sparse. Therefore, this study aimed at developing a methodology for a 1-(13)C(1)-leucine breath test combined with indirect calorimetry, and to apply this technique using broiler diets known to induce differences in protein retention. From 14 days of age onwards, broiler chickens were reared on one of two isocaloric diets with substitutions between fat and protein [low-protein (LP) vs. high-protein (HP) diet: 130.4 vs. 269 g protein/kg; and 101.8 vs. 27.9 g fat/kg]. Every 4 or 5 days, three chickens per diet were placed in the respiratory cells for 48 h. The broilers were intubated with 40 mg 1-(13)C(1)-leucine/kg body weight, followed by breath sampling for 4 h at 15-min intervals and mass spectrometric analysis of the (13)C:(12)C ratio in the samples. The CO(2) level in the respiratory cell air was monitored and excreta samples were collected. The methodology to study l[1-(13)C(1)]leucine decarboxyation in chickens using a breath test combined with indirect calorimetry was accomplished. Results of the nitrogen balance test indicated that the LP broilers had an improved dietary protein retention compared with the HP animals. Moreover, LP chickens decarboxylated a significantly lower percentage of l[1-(13)C(1)]leucine, demonstrating several 'protein- or amino acid-sparing' mechanisms in animals reared on a diet with lower protein level, both at the digestive and at the postabsorptive level.     

纳米氧化锌对肉鸡生长性能和屠宰性能的影响

【研究目的】本试验研究了纳米氧化锌对肉鸡生长性能和屠宰性能的影响。【方法】选用1日龄AA肉鸡192只,随机分为4个处理组,每组设4个重复,每重复12只鸡。在玉米-豆粕型日粮基础上添加纳米氧化锌0（对照）、40、80、120mg/kg,试验期6周。【结果】试验结果表明：整个试验期内,添加纳米氧化锌的试验组平均增重与对照组差异不显著（P＞0.05）。1~21d,纳米氧化锌在40mg/kg的添加水平肉鸡的饲料消耗显著低于对照组(P＜0.05）;料重比差异极显著(P＜0.01）;22~42d,纳米氧化锌在40mg/kg的添加水平肉鸡料重比显著低于对照组（P＜0.05）。于21、42日龄,每处理随机抽取12只,每重复3只,屠宰测定屠宰指标。结果表明：21d时试验组对肉鸡屠宰性能未产生显著影响（P＞0.05）,但所有测定指标中试验组均高于对照组（P＞0.05）;42d时纳米氧化锌在40mg/kg的添加水平肉鸡的屠宰率极显著高于对照组(P＜0.01）,肉鸡半净膛率显著高于对照组(P＜0.05）;添加纳米氧化锌的试验组肉鸡全净膛率、腹脂率、腿肌率、胸肌率与对照组差异不显著（P＞0.05）。【结论】因此,纳米氧化锌在40mg/kg的添加水平对提高肉鸡生长性能和屠宰性能效果最佳。     

Effects of a blend of thyme,peppermint and eucalyptus essential oils on growth performance,serum lipid and hepatic enzyme indices,immune response and ileal morphology and microflora in broilers

This study was conducted to evaluate the effect of a blend of essential oils (EOB) derived from thyme (Thymus vulgaris), peppermint (Mentha piperita) and eucalyptus (Eucalyptus globules) as a natural growth promoter. Five dosages (0 (CON), 50, 100, 150 and 200 ppm) of EOB were added daily to the drinking water to determine its effect on growth performance, carcass quality, blood biochemistry, immune response and ileal morphology in Ross 308 broiler chicks. A total of 500, 10‐day‐old male Ross 308 broilers were allocated into five treatments with four replicates each. Inclusion of EOB at 150 ppm improved (p < 0.05) body weight gain, feed conversion ratio and production index by 11.73, 10.81 and 24.13% compared to CON respectively. The inclusion of EOB at 100, 150 and 200 ppm increased (p < 0.05) carcass yield and thigh muscle compared to CON. Serum concentration of hepatic enzymes (alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase) was decreased while the ileal villus height and ratio of villus height to crypt depth were improved (p < 0.05) in response to inclusion of 150 and 200 ppm of EOB compared to CON. The ileal Escherichia coli count was lower and Lactobacillus count was higher in EOB‐200 and EOB‐150, respectively, compared to CON at 21 and 42 days of age (p < 0.05). Antibody titre of Newcastle, bronchitis and infectious bursal disease was linearly increased (p < 0.05) by increasing supplemental level of EOB at day 4 post‐inoculation. Our results suggested that supplementation of EOB at the 150 ppm into drinking water during day 11–42 could improve growth performance, humoral immunity and ileal morphology and microflora in broilers, and thus, EOB has merit to be used as an alternative to antibiotic growth promoters.     

Efficacy of a Litter Amendment to Reduce Pododermatitis in Broiler Chickens

Broiler house environment, especially volatile NH₃ content, has a significant effect on pododermatitis in chickens. The efficacy of NaHSO₄ in reducing pododermatitis in broiler chickens was investigated in this study. A total of 960 straight-run 1-d-old chicks were randomly assigned to 16 environmental chambers with 4 different levels of NaHSO₄ (4 chambers/treatment). The treatments (TRT) comprised of TRT 1 (control), TRT 2 with NaHSO₄ applied at 1 × rate (0.22 kg/m²) on the day of placement of chicks, TRT 3 with NaHSO₄ applied at 2 × rate on the day of placement of chicks, and TRT 4 with NaHSO₄ applied at 1 × rate on the day of placement of chicks and at 1 × rate on 21 d. Birds were raised to 49 d of age on a 4-stage feeding program with diets formulated to contain high protein levels and all-vegetable ingredients. At 35 d of age, the litter was moistened artificially to see the effect of NaHSO₄ on NH₃ volatilization. In addition to assessing live performance, feet were scored on 42 and 49 d of age for incidence and severity of pododermatitis. Ammonia concentration (ppm) in the chambers was measured before placement of chicks and on a weekly basis throughout the experiment. No differences in live performance of the birds were observed throughout the study (P > 0.05). Sex had significant effects on incidence of pododermatitis (P < 0.05), with females showing higher incidence of pododermatitis than males. The NaHSO₄ had a significant effect on NH₃ volatilization in the chambers (P < 0.05). Ammonia concentration was significantly reduced in all TRT except the control (TRT 1). Sodium bisulfate had no significant effect on NH₃ levels after 35 d upon addition of moisture to the litter. Although not significant (P > 0.05), using NaHSO₄ as a litter amendment numerically reduced the incidence of pododermatitis by 10 or more percentage points.     

河田鸡与艾维茵肉鸡睾丸N-乙酰-β-D-氨基葡萄糖苷酶的特性比较

河田鸡和艾维茵肉鸡的睾丸,经硫酸铵分级沉淀、DEAE-32离子交换柱层析,获得比活力为54.84 U.mg-1,纯化倍数为8.86的河田鸡睾丸N-乙酰-β-D-氨基葡萄糖苷酶(NAGase)制剂.艾维茵肉鸡睾丸NAGase经Sephacry S-300凝胶过滤层析柱进一步纯化,获得比活力为171.50 U.mg-1,纯化倍数为19.8倍的NAGase制剂.以对硝基苯-N-乙酰-β-D-氨基葡萄糖苷(pNP-NAG)为底物,研究酶催化底物水解的反应动力学.结果表明:河田鸡和艾维茵肉鸡睾丸NAGase的最适pH分别为5.6、5.7,最适温度分别为55、50℃;NAGase分别在pH为3.0-9.2、4.0-9.2及温度为10-60、10-30℃下能保持稳定;NAGase酶促反应动力学均符合米氏双曲线方程,测得米氏常数(Km)分别为0.223、0.319 mmol.L-1,最大反应速度(Vm)分别为9.438、6.238μmol.L-1.m in-1;NAGase催化pNP-NAG反应的活化能分别为85.74、73.47 kJ.mol-1.     

An investigation of a reported case of white striping in broilers

Market reports of white striping in broiler breast fillets have been increasing, which has generated concerns in the broiler meat industry regarding negative effects on consumer acceptance. This study was conducted to macro- and microscopically characterize the condition of white striping at varying degrees of severity on Cobb 500 broiler breast fillets slaughtered at 42 d of age. Carcasses of 2,512 broilers presenting white striping were slaughtered and macroscopically classified according to the degree of severity of the striations as moderate or severe; further histological microscopic evaluation demonstrated degenerative myopathy in both moderate and severe cases, but 75% of those breast fillets were classified as moderate. Typically, the samples classified macroscopically as moderate showed microscopic necrosis only (65.17%) or moderate multifocal necrosis (9.83%), whereas those classified as severe showed diffuse and strong necrosis (25.00%). The proliferation of connective tissue was not observed for either of the degrees of white striping investigated, characterizing this profile as an acute occurrence.     

VA5免疫增强剂对鸡新支流三联疫苗免疫效力及肉鸡生产性能的影响

将VA5复方免疫增强剂与市售鸡新城疫–传染性支气管炎–禽流感(H9亚型)三联油乳剂灭活疫苗(以下简称“新支流三联疫苗”)合用免疫黄羽肉鸡,检测免疫后肉鸡的抗体效价、细胞因子及生产性能变化,评价VA5对鸡新支流三联疫苗的免疫增强作用及对肉鸡生产性能的影响。结果表明：黄羽肉鸡免疫含VA5的新支流三联疫苗后,在相同免疫剂量和免疫时间,血清和支气管肺泡冲洗液中针对新城疫病毒(NDV)、传染性支气管炎病毒(IBV)和H9亚型禽流感病毒(AIV(H9))的血凝抑制(HI)抗体效价均显著高于无VA5疫苗组的;泪液及小肠黏液中针对NDV、IBV和AIV(H9)的IgA抗体效价均高于无VA5疫苗组的;血清中IFN–γ和IL–4质量浓度均极显著高于无VA5疫苗组的;肉鸡出栏前,免疫含VA5的新支流三联疫苗组针对NDV和AIV(H9)的HI抗体合格率高于无VA5疫苗组的;添加VA5,提高了肉鸡平均成活率和上市率,同时降低了平均料肉比、呼吸道致病发病率和死淘率,增加了鸡只均质量,只均综合经济效益增幅达11.67%。综上所述,VA5免疫增强剂能提高新支流三联疫苗对黄羽肉鸡的免疫效力,同时提高了生产性能。     

甘氨酸水杨醛席夫碱铜配合物替代金霉素对肉鸡生产性能及铜残留的影响

试验选用300只1日龄健康从雏鸡,随机分为6个组,每个组50只雏鸡,公母各半.1个对照组,5个试验组.测定主要组织(心脏、肝脏、肾脏、骨骼、胸肌、腿肌)中铜元素的含量.结果表明:全期平均日增重试验组Ⅰ比对照组Ⅰ提高了9.84;(P<0.05);试验组Ⅱ、Ⅲ、Ⅳ、Ⅴ的平均日增重比对照组Ⅰ分别提高了-0.71;、2.76;、10.67;(P<0.05)、4.19;;全期平均料重比对照组Ⅰ和试验组Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ差异均不显著(P>0.05).22日龄试验组Ⅱ样品含铜超标率按上述组织顺序分别为:20;、20;、10;、0、0、 0;试验组Ⅲ含铜超标率分别为:10;、10;、0、0、0、0;其余各组均未出现超标情况;42日龄试验组Ⅱ样品含铜超标率分别为:20;、10;、0、0、0;试验组Ⅲ含铜超标率分别为:10;、10;、0、0、0、0;其余各组均未出现超标情况.组织中铜的含量:心脏>肝脏>肾脏>骨骼>胸肌>腿肌.因此,试验组Ⅳ为最适宜添加剂量组.