生长速度

在测量生长速度时,利用国际标准度量单位(g/d)优于盎司/d或磅/周等英制单位,因为英制的测量单位不是非常精确,尤其是对小猪而言. 在实际生产中,平均日增重(Average Daily Gain,ADG)或每日活体增重(Daily Liveweight Gain,DLWG)是评估猪生长速度的首选词,但在营养学与遗传学研究论文中也常遇到"瘦肉组织增重率(Lean Tissue Growth Rate,LTGR)"这一名词.     

Pregnancy rate and first-service conception rate in Angus heifers

The objective of this project was to determine the genetic control of conception rate, or pregnancy percentage in Angus beef heifers. Producers from 6 herds in 5 states provided 3,144 heifer records that included breeding dates, breeding contemporary groups, service sires, and pregnancy check information. Two hundred fourteen sires of the heifers were represented; with 104 sires having less than 5 progeny, and 14 sires having greater than 50 progeny. These data were combined with performance and pedigree information, including actual and adjusted birth weights, weaning weights, and yearling weights, from the American Angus Association database. Heifer pregnancy rate varied from 75 to 95% between herds, and from 65 to 100% between sires, with an overall pregnancy rate of 93%, measured as the percentage of heifers pregnant at pregnancy check after the breeding season. Pregnancy was analyzed as a threshold trait with an underlying continuous distribution. A generalized linear animal model, using a relationship matrix, was fitted. This model included the fixed effects of contemporary group, age of dam, and first AI service sire, and the covariates of heifer age at the beginning of breeding, adjusted birth weight, adjusted weaning weight, and adjusted yearling weight. The relationship matrix included 4 generations of pedigree. The heritability of pregnancy and first-service conception rates on the underlying scale was 0.13 +/- 0.07 and 0.03 +/- 0.03, respectively. Estimated breeding values for pregnancy rate on the observed scale ranged from -0.02 to 0.05 for sires of heifers. Including growth traits with pregnancy rate as 2-trait analyses did not change the heritability of pregnancy rate. As expected for a reproductive trait, the heritability of pregnancy rate was low. Because of its low heritability, genetic improvement in fertility by selection on heifer pregnancy rate would be expected to be slow.     

提高肉用犊牛存活率、健犊率的新措施

提高肉用犊牛生产效率和生产水平已经成为我国肉牛养殖业关键环节,文章根据已有研究结论结合笔者多年实践经验,总结出了一套从肉用犊牛出生处理、科学吃到初乳、正确哺乳补料到循序渐进断奶操作提高犊牛存活率和健犊率的新措施,以期为提高肉用犊牛生产效率和生产水平带来帮助。     

提高非洲鸵鸟孵化率和健雏率的措施

鸵鸟 (非洲鸵鸟 )是世界上现存的最大禽类 ,具有很高的饲养价值。但是由于非洲鸵鸟的蛋大而重 ,蛋壳厚而结实 ,再加上饲养时间短 ,缺乏经验 ,使得鸵鸟人工孵化的孵化率、健雏率都很低 ,严重影响了其经济效益的发挥。本文就提高非洲鸵鸟人工孵化率和健雏率的措施进行讨论 ,供鸵鸟饲养者参考。1　种鸟的饲养管理1 1　场址鸵鸟场应建在远离公路、机场、居民闹市区、背风向阳、地势较高且平坦的地方 ,土质以沙土或沙壤土为好。1 2　饲养面积鸵鸟的体型较大 ,人工驯化饲养时间短 ,野性尚存。为了适应这种生活习性 ,成年鸵鸟特别是种鸟的饲养面…     

Comparison of heart rate and heart rate variability obtained by heart rate monitors and simultaneously recorded electrocardiogram signals in nonexercising horses

Heart rate (HR) and heart rate variability (HRV) are often determined with Polar heart rate monitors (HRMs; S810i; Polar, Kempele, Finland). The aims of this study were to compare data from horses obtained by Polar HRMs and a portable Televet electrocardiogram (ECG; 100 version 4.2.3; Kruuse, Marslev, Denmark) device and to determine appropriate recording times in horses (n = 14). Correlations were calculated and a Bland-Altman analysis was carried out to examine agreement between recording systems. For beat-to-beat (RR) interval, uncorrected and corrected data were highly correlated irrespective of the recording system and recording time (r > 0.99, P < 0.001). For HRV variables, standard deviation of RR interval and root mean square of successive RR intervals, correlations higher than 0.9 were obtained between uncorrected and corrected ECG but not Polar data. The RR interval, HR, and HRV from corrected Televet and Polar data at no time differed between the recording systems. However, with the increase in recording time, the RR interval decreased (P < 0.001). Thus, for comparisons, recording intervals of similar length should be chosen. Correlations among RR interval, HR, and HRV variables obtained by ECG and HRMs were highly significant at all recording times (r > 0.9, P < 0.001). Correlations increased with increasing recording time. Bland-Altman graphs showed a strong agreement between HRMs and ECG and mean RR intervals, HR, and HRV variables were close to identical. In conclusion, Polar HRMs are as adequate as ECG recordings in horses. Owing to a low HR in stationary horses, recording times below 2 minutes will underestimate changes in HR and HRV.     

温度对5个蓝莓品种花粉发芽率及坐果率的影响

本研究以5个蓝莓品种为试材,检测不同温度处理2 h后花粉发芽率及自交坐果率。结果表明：温度处理结束后,5个蓝莓品种花粉发芽率随培养时间的延长而增加,整体上呈现出随温度升高而降低的趋势。温度处理后花粉培养12 h的结果表明,蓝丰花粉在处理温度为25℃-37℃时发芽率最高,显著高于其余4个品种;在处理温度为41℃时,花粉发芽率最低,仅为0.67%。处理温度为39℃-41℃时,瑞卡为花粉发芽率最高的品种,显著高于其余4品种。高温降低了5个蓝莓品种的坐果率,布里吉塔坐果率在处理温度达到33℃时显著下降,较对照降低了22.96%。蓝丰、瑞卡和都克坐果率在处理温度为35℃时显著降低。处理温度为41℃时,五个品种中蓝丰坐果率最高。高温降低了5个蓝莓品种花粉发芽率和坐果率。处理温度相同时,花粉发芽率存在品种间差异。瑞卡是39℃-41℃处理后花粉发芽率最高的品种。处理温度为25℃-41℃时,5个蓝莓品种坐果率存在品种间差异。     

Ovulation rate, lambing rate, litter size and embryo survival of Rambouillet sheep selected for high and low reproductive rate

Ewes from lines selected for high and low reproductive rate and a control line bred and selected randomly were endoscopically examined 3 to 5 d after breeding to determine ovulation rates in the fall of 1985, 1986 and 1987. Fertility (ewes lambing per ewe exposed), lambing rate (lambs born per ewe exposed) and litter size (lambs born per ewe lambing) were evaluated at lambing in the spring of each year. Embryonic survival was estimated as the number of lambs born per corpora lutea. Ovulation rates were 1.28, 1.73 and 1.46 for low, high and control lines, respectively. More (P less than .01) single ovulations occurred in low-line ewes than in the other two lines; high-line ewes had more (P less than .01) twin ovulations than did low- or control-line ewes. Fertility did not differ among lines. Selection line affected (P less than .01) lambing rate at first and all services. Control-line ewes had mean lambing rates at first and all services that were intermediate between those of the low and high lines, which were different from each other. Line x age of ewe interactions existed (P less than .01) for lambing rate at all services and litter size at first and all services. High-line ewes had lower lambing rates and litter sizes as 2-yr-olds than other lines, but their performance increased steadily to 6-yr-olds, whereas the low and control lines remained relatively constant. Embryo survival differed (P less than .10) between lines, being 74%, 63% and 67% for low, high and control lines, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of sodium hydroxide treatment on rate of passage and rate of ruminal fiber digestion

Ruminally fistulated lambs were used to measure the effect of sodium hydroxide treatment on rate of passage and rate of ruminal fiber digestion. Corncobs were raised to 60% moisture and treated to a final concentration of 0, 2.5, 5.0, 7.5 and 10.0% NaOH on a dry matter basis. The diets fed contained 80% cobs and 20% supplement, giving a complete mixed diet containing 0, 2.0, 4.0, 6.0 and 8.0% NaOH (dry basis). Chromic oxide was used as an external marker, and rumen samples were collected at 3, 6, 12, 24, 48 and 96 hr post-dosing. As level of NaOH treatment increased, rate of passage increased linearly (P less than .05). Mean ruminal retention time decreased from 32.4 hr for the control diet to 20.7 hr for the 8% NaOH diet. When rate of passage was regressed against NaOH level, the slope of the line was .142%/hr per unit NaOH, with r2 = .733. In another trial, sodium concentrations equal to the 4% NaOH diet were obtained by the addition of 7.3% NaCl to the basal diet. Rates of passage for lambs fed the diet containing NaCl were faster (P less than .05) than for lambs fed the control diet but slower (P less than .05) than for lambs on the 4% NaOH diet. These data suggest that both sodium intake and NaOH treatment affect rate of passage and are additive. Nylon bags containing .15 g cotton were used to measure the rate of ruminal fiber digestion in lambs fed the five NaOH-treated diets. Bags were removed from the rumen after 12, 24, 36 and 48 hr, and the loss in weight were used to estimate ruminal digestion. As level of NaOH increased, the rate of ruminal cotton digestion decreased linearly (P less than .05). When rate of cotton digestion was regressed against NaOH level, the slope of the line was -.488%/hr per unit NaOH, with r2 = .934.     

Reproduction rate and viability of Merino,Nilagiri and halfbred Merino. II. Age specific replacement rate and net reproduction rate

Summary Age specific replacement rate, net reproduction rate and intrinsic rate of population increase were estimated from records over a period of 11 years of Merino, Nilagiri and halfbreds. On an average for every 1000 ewes mated 830 ewes lambed, 917 lambs were born, 898 lambs were weaned and 422 ewe lambs survived to joining age (one and a half years) in Nilagiri sheep. The corresponding figures were 665, 685, 590 and 228 in Merino and 664, 709, 691 and 341 in halfbreds. Nilagiri ewes in intermediate ages had more multiple births and older ewes weaned more lambs. The flock strength was not maintained unless the ewes were kept till the fifth lambing in Merino, third lambing in Nilagiri and fourth lambing in halfbred Merino. These results along with the culling levels indicated that the low reproductive efficiency in halfbreds may not be critical enough to avoid introduction of Merino for improvement in productivity. However, the poor reproductive efficiency of the Merino in this country may necessitate repeat importations of Merino rams for production of halfbreds.

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Resumen Se estimó la tasa específica de edad de reemplazo, la tasa neta de reproducción y la tasa intrínsica de incremènto poblacional, a partir de registros tomados a través de II a?os, de ovejas de las razas Merino, Nilagiri y Merino media sangre. En promedio, por cada 1000 ovejas apareadas, 830 parieron, 917 corderos nacieron, 898 corderos se destetaron y 422 alcanzaron la edad de apareamiento (1 1/2 a?os), en ovejas Nilagiri. Los promedios correspondientes en Merino, fueron 665, 685, 590 y 228, y en Merino media sangre 664, 709, 691 y 341. Las ovejas Nilagiri en edad intermedia, tuvieron más mellizos y las ovejas más viejas, destetaron más corderos. La vitalidad del reba?o no se pudo mantener, a memos que las ovejas se dejaran hasta el quinto parto en Merino, tercero en Nilagiri y cuarto parto en media sangre. Estos resultados junto con los niveles de descarte, indicaron, que la baja eficiencia reproductiva de las media sangre, posiblemente no es suficientemente crítica, para evitar la introducción de sangre Merino, tendiente al mejoramiento de la productividad. Sin embargo, la pobre eficiencia reproductiva de la raza Merino observada en el país, solo podría superarse mediante la importación contínua de machos, para la producción de media sangre.

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Résumé Le taux de renouvellement, le taux net de reproduction et le taux intrinsèque d’augmentation de la population ont été enregistrés pendant une période de onze ans pour les races Mérinos, Nilagiri et demi-sang. En moyenne, on a eu 917 agneaux nés pour 1000 brebis accouplées/830 brebis agnelantes; 898 agneaux ont été sevrés et 422 jeunes brebis ont survécu jusqu’à l’age de la lutte (un an et demi) dans la race Nilagiri. Pour les Mérinos, les chiffres correspondant sont: 665, 685, 590 et 228, et pour les demi-sang: 664, 709, 691 et 341. Les brebis Nilagiri d’age intermédiaire ont eu plus de naissances multiples et les plus vielles brebis donnent naissance à plus d’agneaux. Pour que l’effectif du troupeau se maintienne, les brebis doivent être conservées jusqu’au cinquième agnelage chez les Mérinos, au troisième chez les Nilagiri et au quatrième chez les croisés Mérinos. Ces résultats, ainsi que les niveaux de réforme, indiquent que le bas rendement en reproduction des demi-sang n’est pas suffisamment crucial pour éviter l’introduction de Mérinos dans le but d’augmenter la productivité. Toutefois les maigres performances de reproduction du Mérinos dans le pays obligent à des importations répétées de béliers Mérinos pour la production des demi-sang.

     

Heart rate and heart rate variability of healthy cats in home and hospital environments

To investigate heart rate and its variability, a telemetry device was affixed to 16 healthy, young cats. Prior to inclusion in the study, cats were subject to echocardiographic examination. The heart rate (HR) when cats were restrained for echocardiography (HR(r)) was calculated from 4-5 consecutive RR intervals obtained from a simultaneously recorded electrocardiogram. Electrocardiographic data were then acquired by telemetry in a quiet room in the veterinary hospital (VTH) and later, in the owner's home (home). The ambulatory data were digitally sampled and the RR interval tachogram from a 4 min epoch subject to Fast Fourier Transform to yield measures of heart rate variability (HRV). Sinus arrhythmia was often observed in resting cats. Heart rates (bpm) expressed as mean (+/-SD) were: HRr: 187 (+/-25), HRVTH: 150 (+/-23), HR(home): 132 (+/-19); each of these rates was significantly different from the others. Significant differences in profiles of HRV suggested that sympathetic tone was higher (and parasympathetic tone lower) when cats were in the hospital.     

提高鹧鸪种蛋孵化率的措施

种蛋要求来源于没有传染病的非疫区、卫生防疫好、饲料符合营养标准、公母比例适当的健康鹧鸪群。种蛋受精率应在80％以上。蛋重符合品种特征，蛋形、蛋重、色泽、蛋壳厚薄适宜，剔除脏蛋、过大、过小、畸形、裂纹蛋。蛋重一般在20-25克为宜。要选择新鲜的、保存时间在一周内的种蛋，一般不要超过5天。     

Ovulation rate and twinning rate in cattle: heritabilities and genetic correlation

Repeated measures of ovulation rate on puberal heifers should be an effective way to select for increased twinning rate. A reliable estimate of the genetic correlation between ovulation and twinning rates is needed to implement such selection and to predict its efficiency. Restricted maximum likelihood was used to estimate genetic correlations from subsets of data collected from the twinning project at the Roman L. Hruska U.S. Meat Animal Research Center. The animal model included numerator relationships among the animals and fixed effects of year-season of measurement, age at measurement, and birth group. Genetic correlations between averages of ovulation rates for three, four, five, six, seven, and eight estrous cycles and the occurrence of twins were, respectively, .62, .76, 1.00, 1.00, 1.00, and .98 based on observations on 200 to 325 puberal heifers. Corresponding phenotypic correlations ranged from .06 to .26. Genetic correlations between ovulation rate in a single estrous cycle and occurrence of twins were .38, .98, and .98, respectively, for 323, 430, and 283 cows with ovulation rate measured after measurement of twinning, in the same season as measurement of twinning, and more than 1 yr before measurement of twinning. Phenotypic correlations were .00, .07, and .00. Genetic and phenotypic correlations among ovulation rates at six consecutive estrous cycles averaged, respectively, .66 and .12 for 610 heifers. Heritabilities for ovulation rates in individual cycles averaged .16. No evidence of negative environmental covariance between ovulation rates in adjacent cycles was found. These results support the approach of indirectly selecting for twinning rate by measuring ovulation rates in estrous cycles of puberal heifers.     

汇率及利率调整对商品进出口的影响

中国人民银行日前宣布，经国务院批准．自2005年7月21日起，我国开始施行以市场供求为基础、参考一篮子货币进行调节、有管理的浮动汇率制度。针对广大现货生产、加工、贸易企业关心的人民币汇率变动对利率以及进出口的影响，笔者略作探讨。     

提高波尔山羊超排效果及移植妊娠率研究初报

以波尔山羊为供体、本地白山羊及其用萨能奶山羊改良的高代杂种羊为受体,开展提高超排效果及移植妊娠率研究。结果表明:在提高超排效果研究方面,注射P4+LRH-A3组较对照组头均获胚胎数及可用胚胎的百分率分别提高5.4枚和17.7％;注射P4组、注射LRH-A3组较对照组头均获可用胚胎的百分率分别提高18.99％和14.87％。在提高受体移植妊娠率研究方面,移单胚、双胚、三胚的受体羊移植妊娠率组间差异不显著,但移三胚的受体羊产羔率较移单胚、双胚分别提高66.92％和36.09％,差异极显著;受体羊移入胚胎发育阶段相同的1枚或2枚同等级胚胎(A级或B级),妊娠率和产羔率无显著影响,但移入2枚A级囊胚受体羊的产羔率较移入2枚A级桑椹胚的产羔率高36.23％,差异显著;移植受体的一侧卵巢上有3个以上黄体的妊娠率显著高于1个黄体和2个黄体,分别高31.55％和29.23％,差异显著。移入胚胎的受体羊卵巢上黄体和卵泡同时存在,将卵泡刺破使卵泡液流失,与卵巢上只有黄体存在的受体羊移植妊娠率无显著差异;向子宫角方向和逆子宫角方向移植胚胎对受体羊移植妊娠率无显著差异。     

同窝公母比例不等对留种母猪受胎率的影响研究

按同窝中公猪所占百分经不同，利用计算机分区统计了31682头留种母猪的受胎率。结果表明，同窝公母比例对母猪受胎率的影响效果明显（P＜0．05）。因此同窝中公猪所占比例高于60％时，该窝母猪不宜作种用。     

Effects of time of insemination relative to ovulation on pregnancy rate and embryonic-loss rate in mares

The effects of pre-ovulatory and post ovulatory insemination on pregnancy rate and embryonic-loss rate were studied in 268 mares in two experiments. Within each experiment mares were randomised within replicates as follows: to be inseminated on the day the pre-ovulatory follicle reached 35 mm (pre-ovulatory group), to be inseminated on the day of ovulation (Day 0 group), and to be inseminated on the day after ovulation (Day 1 group). Ultrasonic pregnancy diagnoses were performed on Days 11, 12, 13 and 14 (Experiment 1) and Days 11, 12, 13, 14, 15, 20 and 40 (Experiment 2). Combined for the two experiments, pregnancy rates were different (P less than 0.01) among the three groups. For Experiment 2, pregnancy rate within the pre-ovulatory group was lower (P less than 0.05) for insemination 4 days or more before ovulation than for up to 3 days before ovulation. Pregnancy rate was lower (P less than 0.05) for the Day 0 group than for the pre-ovulatory group inseminated up to 3 days before ovulation. In Experiment 2, ovulation was detected by examinations every 6 h; pregnancy rate was greater (P less than 0.05) for mares inseminated 0 to 6 h after ovulation than for mares inseminated at 18 to 24 h. No pregnancies occurred when mares were inseminated 30 h or more after ovulation. The mean day of first detection of the embryonic vesicle was different (P less than 0.0001) among the three groups. Diameter of embryonic vesicle averaged over Days 11 to 15 also differed (P less than 0.0001) among groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

提高种蛋孵化率的技巧

种蛋孵化率的高低,不仅直接影响到种蛋利用率、出雏率、雏鸡质量,而且还关系到将来的育雏成活率,雏鸡生长速度乃至整个饲养过程的经济效益。但孵化率受诸多因素的制约。现根据有关资料及笔者的实践经验就如何提高种蛋孵化率做一浅述。     

沟叶结缕草草坪蒸散量研究简报

研究了沟叶结缕草Zoysia matrella草坪的蒸散量和作物系数,实测的1998年全年蒸散量为1 098.9 mm,作物系数为0.79.作物系数可以作为定值,计算沟叶结缕草需水量.平常年份沟叶结缕草缺水232.2 mm.