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1.
《中国兽医学报》2019,(11):2222-2226
为研究甘草提取物对氟苯尼考(florfenicol,FFC)在鸡体内药动学和生物利用度的影响,将30只鸡随机分成单用组、合用组和静脉组,合用组连续7 d灌服甘草提取物(0.3 g/kg,1次/d),单用组和静脉组则给予相同体积的生理盐水,第8天3个组均予FFC(30 mg/kg)给药后按时间点连续采样,数据采用DAS2.0进行分析。结果显示,单用组和合用组FFC的主要药动学参数:C_(max)分别为(5.637±0.825),(5.289±0.734) mg/L,T_(max)分别为(1.518±0.428),(1.083±0.343) h,AUC_(0-∞)分别为(30.774±5.683),(24.561±5.364) mg/L·h,t_(1/2z)分别为(2.472±0.314),(2.066±0.272) h,MRT分别为(3.149±0.459),(2.614±0.385) h,Vz分别为(4.466±0.375),(5.253±0.498) L/kg,CLz分别为(1.168±0.136),(1.401±0.152) L/h·kg。合用后,FFC药动学特征出现明显改变,AUC_(0-∞)、MRT、t_(1/2z)、T_(max)均显著降低(P0.05),C_(max)降低(P0.05),Vz和CLz则显著增加(P0.05),口服生物利用度下降了16.26%。结果表明,甘草提取物连续给药7 d后加快了FFC在鸡体内的吸收和消除速度,减小了口服生物利用度,提示两者在临床上合用有潜在的药动学相互作用。 相似文献
2.
氟苯尼考(florfenicol, FFC)是目前临床上应用广泛的动物广谱抗菌药,本研究旨在采用乳化溶剂挥发法制备氟苯尼考纳米晶(florfenicol nanocrystal, FFC-NC)。通过单因素试验优化制备工艺,即以FFC纳米混悬液的粒径大小作为筛选的主要参数,对6个影响因素进行考察,确定最佳制备条件,并对在最优条件下制备的FFC-NC进行物理表征评价。最终确定FFC-NC制备的最佳条件：有机相与水相体积比为1∶2,泊洛沙姆188的浓度为5‰,匀浆速度和时间分别为7 000 r/min和5 min,匀质压力和次数分别为300 bar和3次。利用最佳条件制备得到的FFC-NC平均粒径为(226.1±11.3) nm, PDI平均值为0.29±0.03。FFC-NC的粒径分布在141.8～243.0 nm范围内,表明其粒径分布范围窄。FFC-NC的理化性质表征结果显示,其化学结构未发生改变,纳米晶形态为不规则球体,粒径小且分布均一,纳米晶的晶型结构发生改变。电位测定结果表明,FFC纳米混悬液的稳定性好。本研究突破了传统的FFC-NC制备技术,为其在兽医临床上的使用提供了一种新的... 相似文献
3.
《中国家禽》2016,(4)
试验研究了麻鸭单次静脉注射和肌内注射氟苯尼考后的药动学,给药剂量均为20 mg/kg体重。麻鸭给药后,定点采血,分离血浆,然后以高效液相色谱法测定血浆中的药物浓度,并利用房室分析法计算两种不同给药途径下氟苯尼考的药动学参数。结果显示:静脉注射氟苯尼考表观分布容积(V_β)为(8 388.45±850.43)m L/kg,消除较缓慢,消除半衰期(t_(1/2β))为(6.61±0.83)h;肌内注射氟苯尼考峰浓度(C_(max))为(1.42±0.16)μg/m L,达峰时间(t_(max))为(1.60±0.19)h,绝对生物利用度为71.59%。结果证实氟苯尼考在麻鸭体内具有优异的药动学特征,分布迅速、广泛、消除较缓慢,肌内注射吸收迅速且较完全。结合氟苯尼考对鸭疫里默氏杆菌、沙门菌及大肠杆菌的MIC数据,计算得出对如上3种细菌感染的治疗,静脉或肌内注射20 mg/kg氟苯尼考较难达到良好的治疗效果,应适当增加给药剂量。 相似文献
4.
《中国动物保健》2017,(5)
健康杜长大猪16头(体重为18±1kg)随机分为A、B两组,以20mg/kg剂量单次灌服两种氟苯尼考制剂(20%氟苯尼考粉和2%氟苯尼考预混剂),并于给药后不同时间点从前腔静脉采血,采用已建立的高效液相色谱法(HPLC)进行血药浓度测定,利用Win Nonlin软件的非房室模型拟合其血药浓度-时间数据。方法学研究表明本实验建立的HPLC方法专属性良好,在目标峰附近无杂质干扰,线性良好,线性范围为0.03~10μg/mL,相关系数为0.9994。20%氟苯尼考粉主要药动学参数为:Tmax=1.13±0.64h,Cmax=9.61±2.65μg/mL,T1/2=3.84±1.56h,MRT=4.65±0.70h,AUC=52.56±16.99 h*μg/mL;2%氟苯尼考预混剂主要药动学参数为:Tmax=1.31±0.37h,Cmax=8.30±2.17μg/mL,T1/2=3.39±0.35h,MRT=4.93±0.74h,AUC=49.84±17.54 h*μg/mL。比较药动学结果表明20%氟苯尼考粉相对于2%氟苯尼考预混剂的相对生物利用度为105.45%。经T检验和方差分析,二者主要药动学参数无显著差异,在猪体内可视为有相似的药动学过程,但前者在饮水灌服给药时能在更短的时间吸收分布、达到血药峰浓度,且血药峰浓度略高于2%氟苯尼考预混剂,故20%氟苯尼考粉起效更快、效果稍好于2%氟苯尼考预混剂。 相似文献
5.
超微粉碎对氟苯尼考在肉鸡体内药动学的影响 总被引：2，自引：0，他引：2
为研究超微粉碎对氟苯尼考在肉鸡体内的血药浓度及药动学特征的影响,将20只健康肉鸡随机分为两组,Ⅰ组单剂量灌服氟苯尼考原药(30 mg/kg),Ⅱ组单剂量灌服氟苯尼考超微粉(30 mg/kg).采用高效液相色谱法测定血浆药物浓度,最低检测限为0.004 μg/mL,所得数据用3P97药动学软件进行分析后发现,血药浓度和时间关系均符合一室开放模型,选择的权重为1/C2.主要药动学参数变化原药组和超微粉组的t1/2ka分别为(28.89±4.51)和(23.49±4.48) min,t1/2ke分别为(101.66±9.97) min和(104.57±16.25) min,Tmax分别为(72.86±7.15)和(62.23±4.78) min,Cmax分别为(7.94±0.78)和(8.65±0.67) μg/mL,AUC分别为(33.01±7.73)和(36.87±3.63) μg/(mL·h).结果表明超微粉碎对氟苯尼考在肉鸡体内的药物代谢过程具有较大影响,药物在体内吸收速度加快,达峰时间提前,峰浓度显著提高,生物利用度增加. 相似文献
6.
《中国兽药杂志》2020,(7)
为研究氟苯尼考环糊精包合物的药代动力学及生物利用度,将健康白羽肉鸡24只,随机分为两组,每组12只,分别以20 mg/kg的剂量单次灌服20%普通氟苯尼考粉(A组)和20%氟苯尼考环糊精包合物(B组),并于给药后不同时间点从翅下静脉采血,采用已建立的UPLC-MS/MS测定血浆中的药物浓度,用WinNonlin 5.2.1药动学分析软件的非房室模型拟合血药浓度-时间数据。结果显示:A组达峰时间(T_(max))和达峰浓度(C_(max))分别为1.563±0.755 h、1043.15±391.42 ng/mL,平均消除半衰期(T_(1/2λz))约为4.814±3.058 h,平均曲线下面积(AUC_(last))为4283.53±2406.81 h·ng/mL;B组T_(max)、C_(max)分别为1.417±1.683 h、4691.95±1597.28 ng/mL,T_(1/2λz)约为2.106±1.476 h,AUC_(last)为14911.70±2976.22 h·ng/mL;相对生物利用度约为348.12%。试验表明,采用环糊精包合工艺的氟苯尼考粉的生物利用度显著高于普通工艺的氟苯尼考粉。 相似文献
7.
氟苯尼考在鸡体内的药动学及其体内抗菌后效应研究 总被引：2，自引：0，他引：2
为探讨氟苯尼考的药动学特征及抗菌后效应(PAE),制订临床给药方案,用微生物法测定鸡血清中氟苯尼考浓度。建立鸡组织笼感染模型,以菌落计数法测定氟苯尼考的体内PAE。结果显示内服给药后药-时数据符合一级吸收一室开放式模型,其药动学方程为C=4.7804(e-0.1096t-e-2.5858t),主要药动学参数:t1/2Ke=(6.42±0.83)h、Cmax=(3.96±0.42)μg/mL、AUC=(42.41±7.50)(μg/mL).h-1、Vd=(6.63±0.68)L/kg;氟苯尼考浓度在2MIC、4MIC和8MIC时,作用1h的体内PAE分别为0.35、1.20和1.48h,同时测定的体外PAE为0.23、0.93和1.17h。鸡内服氟苯尼考的给药方案为1日1次,维持剂量30mg/kg体重。 相似文献
8.
《畜牧与兽医》2016,(4):101-103
健康黄羽肉鸡(公母各半)20只随机分为A、B 2组,分别单剂量灌服19.91%氟苯尼考粉(受试品)和10%氟苯尼考粉(对照品),给药量均为15 mg/kg,进行药动学比较研究。给药后按预定时间采集血样,采用高效液相色谱法(HPLC)法测定血浆中药物含量。实测血药浓度-时间数据,采用Win Nonlin 5.2.1药动学分析软件处理。结果显示:A组平均消除半衰期(T_(1/2β))约为9.158 h,达峰时间(T~(max))和峰值浓度(C~(max))分别为0.600 h和5.786μg/m L,平均曲线下面积(AUC)为26.474 h·μg/m L,平均滞留时间(MRT)4.357 h;B组平均T_(1/2β)约为7.513 h,T~(max)和C~(max)分别为1.900 h和5.106 mg/L,AUC为25.749 h·μg/m L,MRT 5.695 h;相对生物利用度约为93.979%。结果表明,19.91%氟苯尼考粉T~(max)比10%氟苯尼考粉提前(P0.01),其他药动学参数无明显差异(P0.05)。 相似文献
9.
本研究旨在考察国产麻保沙星溶液在健康犬体内的药动学特征及生物利用度.选用8只健康犬,按照随机拉丁方设计,进行单次不同单剂量(2.75 mg·kg-1)分别静注麻保沙星溶液和口服麻保沙星溶液制剂.血浆样品经乙腈沉淀血浆蛋白,高速离心,用反相高效液相色谱法测定犬血浆中麻保沙星的浓度,3P97药动学计算软件处理血浆药物浓度-时间数据.健康犬静注给药的药物动力学最佳数学模型为无吸收开放二室模型,主要药动学参数为:T1/2α(0.34±0.14)h,T1/2β(7.74±1.70)h,V(1.03±0.60)L·kg-1,CL(0.22±0.08)L·h-1;AUC(14.05±4.25)mg·mL-1·h.口服给药的药物动力学最佳数学模型为一级吸收二室模型.主要药动学参数为:T1/2α((2.82±1.86)h,T1/2β(16.03±9.27)h,V/F(2.25±0.34)L·kg-1,CL/F(0.21±0.05)L·h-1,Tmax(1.55±0.62)h,Cmax(0.89±0.21)μg·mL-1,AUC(13.66±2.77)mg·mL-1·h.肌注麻保沙星冻干粉针的生物利用度为97.22%.麻保沙星在健康犬体内口服的主要药动学特征为吸收较快,达峰时间短,半衰期较长,生物利用度高. 相似文献
10.
为研究海南霉素钠预混剂在鸡体内的药代动力学特征和生物利用度,将16只健康AA鸡随机分成2组,每组8只,采用平行试验设计对两组鸡分别进行单剂量口服给药和静脉注射给药药动学研究,给药量均为1.5 mg/kg bw(相当于7.5 mg/kg混饲给药)。按预定时间点采集血样,血样中海南霉素的含量采用高效液相色谱-串联质谱法(HPLC-MS/MS)测定,流动相为乙腈-0.1%甲酸水溶液(90:10,V/V)。实测血药浓度-时间数据使用Winnonlin 5.2药动学分析软件拟合药动学参数。鸡口服给药的药动学参数如下:平均消除半衰期为(T_(1/2β))约为30.44 h,平均滞留时间(MRT)约为36.40 h,在血浆中的达峰时间(T_(max))约为0.5 h,达峰浓度(C_(max))约为68.87 ng/mL,平均药时曲线下面积(AUC)约为654.95 ng·h/mL,平均生物利用度(F)约为32.82%。鸡静脉注射给药的药动学参数如下:平均消除半衰期约为(T_(1/2β))为46.40 h,平均滞留时间(MRT)约为30.91 h,平均血浆清除率(CL)约为1.59 L/(kg·h),平均表观分布容积(V_d)约为116.05 L/kg。结果表明海南霉素进入鸡体后分布广泛,消除缓慢,半衰期长;口服海南霉素钠预混剂吸收迅速,但吸收不完全。 相似文献
11.
新型兽用纳米乳载药系统在大鼠体内的药代动力学研究 总被引：1，自引：1，他引：0
为了解氟苯尼考纳米乳(FFNE)在大鼠体内药代动力学行为,本试验以氟苯尼考溶液(FFSol)为参比制剂,以30 mg/kg剂量给大鼠灌胃和肌内注射给药,分别于给药后0.5、1、2、4、8、12、24、36、48、72 h采血,利用高效液相色谱法测定血浆中氟苯尼考含量,利用DAS 2.0软件计算房室模型与非房室模型条件下药代动力学参数。结果显示,在两种给药方式下,FFNE与FFSol在大鼠体内均符合二室模型。灌胃给药后,FFNE与FFSol在房室模型条件下AUC(0-∞)分别为1 085.047和2 176.490 mg/L·h,半衰期分别为10.566和13.687 h,FFNE的相对生物利用度为187.4%。肌内注射给药后,FFNE与FFSol在房室模型条件下AUC(0-∞)分别为1 530.55和3 243.338 mg/L·h,半衰期分别为7.533和13.335 h,FFNE的相对生物利用度为211.9%。结果表明,FFNE通过灌胃和肌内注射给药在大鼠体内分布较广,灌胃相对肌内注射吸收差,消除快。将氟苯尼考制成纳米乳剂后促进了氟苯尼考的吸收,氟苯尼考的生物利用度显著提高。 相似文献
12.
W. CYBULSKI P. LARSSON† H. TJÄLVE† H. KOWALSKA-PYLKA M. SYLLA S. SEMENIUK‡ 《Journal of veterinary pharmacology and therapeutics》1996,19(5):352-358
Hens were given single intravenous or oral doses (30 mg/kg body weight) of metronidazole and the plasma concentrations of the drug were determined by high-performance liquid chromatography (HPLC) at intervals from 10 min to 24 h after drug administration. Pharmacokinetic variables were calculated by the Lagrange algorithm technique. The elimination half-life ( t 1/2β ) after the intravenous injection was 4.2 ± 0.5 h, the volume of distribution ( V d(ss) ) 1.1±0.2 L/kg and the total body clearance ( Cl B ) 131.2 ± 20 mL/h.kg. Oral bioavailability of the metronidazole was 78 ± 16%. The plasma maximum concentration ( C max ) 31.9 ± 2.3 μg/mL was reached 2 h after the oral administration and the oral elimination half-life ( t 1 /2β) was 4.7 ± 0.2 h. The binding of metronidazole to proteins in hen plasma was very low (less than 3%). Whole body autoradiography of [3 H] metronidazole in hens and quails showed an even distribution of labelled material in various tissues at short survival intervals (1-4 h) after oral or intravenous administration. A high labelling was seen in the contents of the small and large intestines. In the laying quails a labelling was also seen in the albumen and in a ring in the periphery of the yolk at long survival intervals. Our results show that a concentration twofold above the MIC is maintained in the plasma of hens for at least 12 h at an oral dose of 30 mg/kg metronidazole. 相似文献
13.
采用反溶剂法制备妥曲珠利微晶体,利用显微镜观察妥曲珠利微晶体与妥曲珠利原药显微特征差异,并在25℃条件下测定两者体外溶出速率差异。将12只家兔随机分为2组,每组6只,分别按药物剂量10mg/kg灌胃,单剂量给药,采用HPLC检测血药浓度;用DAS2.0药代动力学程序计算药代动力学参数。结果显示,成功制备了妥曲珠利微晶体,微晶体与原药的显微特征差异明显,体外溶出速率明显加快;家兔单剂量灌胃妥曲珠利和微晶体后,主要药动学参数Cmax分别为（8.925±0.360）mg/L和（12.510±0.525）mg/L,tmax均为24h,AUC（0-∞）分别为（411.605±20.918）mg/（L·h）和（578.650±11.664）mg/（L·h）,相对生物利用度为140.6%,药时数据符合一级吸收二室模型。结果表明,HPLC法适用于妥曲珠利血浆浓度的测定;妥曲珠利微晶体与妥曲珠利原药相比,体内吸收速率和吸收程度有较大的提高。 相似文献
14.
Study of pharmacokinetics of an in situ forming gel system for controlled delivery of florfenicol in pigs 
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下载免费PDF全文 Z.‐X. Geng H.‐M. Li J. Tian T.‐F. Liu Z.‐G. Yu 《Journal of veterinary pharmacology and therapeutics》2015,38(6):596-600
To reduce florfenicol (FFC) administration frequency in veterinary use, the drug was currently developed into in situ forming gel. Twelve pigs were randomly divided into two groups (six pigs per group). A single i.m. dose of 40 mg/kg body weight (b.w.) was given to pigs, group one was given FFC in situ forming gel, and group two was given FFC conventional injection. High‐performance liquid chromatography (HPLC) was used to determine FFC plasma concentrations. There were significant differences (P < 0.01) between FFC in situ forming gel and conventional injection, in pharmacokinetic parameters MRT (mean retention time) (57.79 ± 2.88) h versus (15.94 ± 1.29) h, AUC (area under the concentration–time curve) (421.54 ± 8.97) μg·h/mL versus (168.16 ± 4.59) μg·h/mL, tmax (time of occurrence of cmax) (9.00 ± 2.68) h versus (4.33 ± 0.82) h, cmax (maximum plasma concentration) (6.87 ± 0.66) μg/mL versus (12.01 ± 0.66) μg/mL, t1/2λz (terminal elimination half‐life) (38.04 ± 2.20) h versus (9.15 ± 2.71) h. The results demonstrated that the in situ forming gel system could shorten dosing interval of FFC and thus achieved less frequent administration during long‐term treatment. 相似文献
15.
Abstract AIM: To determine the pharmacokinetics and bioavailability of florfenicol in the plasma of healthy Japanese quail (Coturnix japonica). METHODS: Sixty-five quail were given an I/V and I/M dose of florfenicol at 30 mg/kg bodyweight (BW). A two-period sequential design was used, with a wash-out period of 2 weeks between the different routes of administration. Concentrations of florfenicol in plasma were determined using high-performance liquid chromatography (HPLC). RESULTS: A naíve pooled data analysis approach for the plasma concentration-time profile of florfenicol was found to fit a non-compartmental open model. After I/V administration, the mean residence time (MRT), mean volume of distribution at steady state (Vss), and total body clearance of florfenicol were 12.0 (SD 0.37) h, 8.7 (SD 0.22) L/kg, and 1.3 (SD 0.08) L/h/kg, respectively. After I/M injection, the MRT, mean absorption time (MAT), and bioavailability were 12.3 (SD 0.37) h, 0.2 (SD 0.02) h, and 79.1 (SD 1.79)%, respectively. CONCLUSIONS: The time for the concentration of florfenicol to fall below the probable effective concentration of 1 µg/ml of approximately 10 h is sufficient for the minimum inhibitory concentration needed for many bacterial isolates. Further pharm acodynamic studies in quail are needed to evaluate a suitable dosage regimen. 相似文献
16.
G.‐Y. Wang P. Tu X. Chen Y.‐G. Guo S.‐X. Jiang 《Journal of veterinary pharmacology and therapeutics》2013,36(5):494-501
Drug–drug interactions (DDIs) may adversely affect the prevention and cure of diseases. The effects of three polyether ionophore antibiotics, salinomycin (SAL), monensin (MON), and maduramycin (MAD) on the pharmacokinetics of florfenicol (FFC) were investigated in broilers. The chickens were fed rations with or without SAL (60 mg/kg feeds), MON (120 mg/kg feeds), or MAD (5 mg/kg feeds) for 14 consecutive days. FFC was given to the chickens either intravenously (i.v.) or orally (p.o.) at a single dose of 30 mg/kg body weight. Blood samples were taken from each chicken at 0–24 h postadministration of FFC. The plasma concentration of FFC was detected by high‐performance liquid chromatography. The plasma concentration of FFC decreased with i.v. or p.o. co‐administration of SAL, MON, or MAD in broilers, implying occurrence of DDIs during the co‐administration of FFC with these ionophores. Our findings suggest that more attention should be given to the use of FFC to treat bacterial infections in chickens supplemented with polyether ionophore antibiotics. 相似文献
17.
研究氟苯尼考磺酸盐在肉鸡体内的血药浓度及药动学特征。将12只健康三黄肉鸡,单次肌肉注射推荐治疗剂量（20mg／kg）的自制2％氟苯尼考磺酸盐。采用高效液相色谱法测定血浆药物浓度,所得数据用3P97药动软件进行分析后发现,血药浓度和时间关系符合一级吸收一室模型,选择的权重为1／C。主要药动学参数为T1／2kα：（0．28±0．04）h,T1/2Ke：（2．06±0．06）h,Cmax：（4．17±0．12）μg／mL,Tmax：（0．92±0．09）h,AUC：（16．89±0,35）μg／mL,V／F（c）：（3．52±0．13）L／kg,CL／F（s）：（1．19±0．03）L／（kg·h）,Ke：（0．34±0．01）／h,kα：（2．57±0．37）／h,A：（6．56±0．38）μg／mL。结果提示,氟苯尼考磺酸盐在肉鸡体内具有吸收迅速,分布广泛、峰浓度较高以及消除较快的动力学特征。 相似文献
18.
Zhiqiang Chang Zhao Chen Haiyu Gao Qianqian Zhai Jian Li 《Journal of veterinary pharmacology and therapeutics》2019,42(1):121-125
The pharmacokinetic profiles of florfenicol in the spotted halibut (Verasper variegatus) were investigated at 15 and 20°C water temperatures, respectively. Florfenicol content in plasma samples was analyzed using an HPLC method. Drug concentration versus time data were best fitted to a three‐compartment model after a single intravenous administration (15 mg/kg BW), and fitted to a two‐compartment model after an oral administration (30 mg/kg BW) at 15 and 20°C. The florfenicol concentration in the blood increased slowly during the 12 hr following an oral administration at 15°C, with a peak concentration (Cmax) of 9.1 mg/L, and then declined gradually. The half‐lives of absorption, distribution, and elimination phase were 2.18, 5.66 and 14.25 hr, respectively. The bioavailability (F) was calculated to be 24.14%. After an oral administration at 20°C, shorter half‐lives of absorption (1.33 hr), distribution (2.51 hr) and elimination (9.71 hr), a higher Cmax (12.2 mg/L), and a similar F (23.98%) were found. Based on the pharmacokinetics and pharmacodynamics, an oral dose of 30 mg/kg BW was suggested to be efficacious for bacterial disease control in spotted halibut farming. 相似文献
19.
Kim EY Gebru E Lee JS Kim JC Park SC 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2011,73(4):463-466
A pharmacokinetic study of a commercial florfenicol-tylosin (2:1) combination product was conducted in six beagle dogs after intravenous (IV) and intramuscular (IM) administration at doses of 10 mg/kg (florfenicol) and 5 mg/kg (tylosin). Serum drug concentrations were determined by a validated high performance liquid chromatography (HPLC) using UV detection. A rapid and nearly complete absorption of both drugs with a mean IM bioavailability of 103.9% (florfenicol) and 92.6% (tylosin), prolonged elimination half-life, and high tissue penetration with steady state volume of distribution of 2.63 l/kg (florfenicol) and 1.98 l/kg (tylosin) were observed. Additional studies, including pharmacodynamic and toxicological evaluation are required before recommendations can be made regarding the clinical application of the product in dogs. 相似文献
20.
The independent effects of age and body weight (BW) on photostimulatory response in turkey breeder hens were studied by measuring changes in plasma luteinizing hormone (LH; ng/mL) before and 3 d after photostimulation. The study was conducted with hens from two BW groups at 24–25, 27–28, and 31–32 wk of age. There was approximately a 1-kg difference in BW between groups within an age. Six hens per BW and age group were cannulated (jugular vein) and serially sampled during each of two 6-hr periods. Samples were collected at 10-min intervals. The two sampling periods were the last 6 hr of the short-day photoperiod (SD) and the same period during the third long day after photostimulation (LD). The photostimulatory response (PR) or difference between the SD and LD baseline LH concentrations was greatest in the 24–25-wk-old hens. The PR was unaffected by hen BW at any age. The baseline LH concentration during the SD photoperiod declined as hens aged. After photostimulation, baseline LH and LH peak amplitude concentrations were higher in 24–25-wk-old hens compared with the older ages. The number of LH peaks increased after photostimulation, but there were no significant effects attributable to age or BW within an age. In conclusion, the PR was affected by hen age but not hen BW or BW within a particular age. 相似文献