Letters

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Endogenous N-losses in piglets estimated by a [15N]-isotope dilution technique: effect of xylanase addition to a wheat and rye based diet.

The nitrogen pool of piglets weighing 19.4 +/- 1.4 kg at the beginning of the experiment was labeled with an oral application of ([15N]H4)2SO4 (1.26 [15N]-atom percent excess of dietary N) over a period of 7 d. The labeling period was followed by an equilibration period of 7 d without feeding the labeling compound. The two experimental diets were based on wheat (53%) and rye (25%) and were fed either with or without a xylanase containing enzyme preparation over both experimental periods. Additionally, diets were supplemented with an indigestible marker during the 2nd period of the experiment to allow the calculation of endogenous N-losses in subsequent segments of the digestive tract of the pigs. These endogenous N-losses were estimated at the end of the experiment by analyzing feces, ingesta and urine for [15N]-enrichment assuming that [15N]-enrichment of urine represents the [15N]-enrichment of the precursor pool. Endogenous N-losses were not significantly affected by xylanase addition at any measurement site (stomach, 3 sections of the small intestine, total digestive tract). Endogenous N-proportions of total nitrogen amounted on average for the six pigs to 42 +/- 11% and 56 +/- 5% at the last section of the small intestine and over the whole digestive tract, respectively, which corresponded to endogenous N-losses of 2.8 +/- 1.3 g N/kg DM and 2.0 +/- 0.3 g N/kg DM, respectively.     

Economic analysis of vaccination applied to ovine listeriosis

An economic model for determining whether vaccination against a disease would be beneficial financially on individual farms is proposed; it is based on four pieces of information: the costs of a disease case including its treatment, the cost of vaccinating each animal including veterinary fees, the expected incidence of the disease, and the efficacy of the vaccine. The model was applied to ovine listeriosis, which is a serious disease problem in Norway. Vaccination appeared to be beneficial for the average sheep flock of 100 ewes which might expect two or more cases of listeriosis per year. Furthermore, the model suggests the ratio of the price of a single vaccination to the cost of a disease case can be used to plan more efficient vaccine field trials.     

云南东方蜜蜂形态特征与环境因子相关性的研究

云南东方蜜蜂种群内遗传变异丰富 ,每个形态性状特征均具有丰富的多态性 ,种群间具多型性 ,且种群中许多形态性状特征表现出较明显的地理变异性[1～ 3 ] 。从滇南 -滇中 -滇西北 ,随纬度或海拔的增加 ,形态特征变异的总趋势是 :蜜蜂个体增大、体色变深。具体是 :1.前翅长、宽 ,背板 3、 4宽 ;2 .后腿长 ,蜡镜长、宽 ,蜡镜间距 ,腹片 3、 6的长和宽逐渐增加 ;3.背板 3、 4的色素度 ,小盾片的色素度逐渐加深。云南东方蜜蜂种群形态性状的多态性、多型性及其生态地理变异式样 ,均具有生态适应意义 :与云南东方蜜蜂分布区的气候特点相适应 ,而且还与海拔高度和纬度的变化有着密切的适应关系     

The onset and course of estrus in young heifers]

In 1990 three experiments were performed in heifers 184 to 505 day-old with the weight 190 to 390 kg to test some biotechnical methods while studying the level of reproduction functions. Heifers were examined in 4 to 24-hour intervals by direct observations of animal behaviour, by clinical and gynaecological examinations of larger animals. The progesterone concentration in the peripheral blood was determined by the RIA method and simultaneously with the blood samplings, the values of impedance of vaginal mucosa were measured by means of several types of the Estral device (CSFR) for cattle. To detect the functional responses to prostaglandins administered, the following forms of substances were used: racemic mixture of optically active forms D (+) and L (-) in the Czechoslovak preparation Oestrophan inj. Spofa (0.25 mg of cloprostenol in 1 ml of solution) and the dextrorotatory D isomer--cloprostenol (0.075 mg in 1 ml of solution) in the Czechoslovak preparation Remophan inj. Spofa. Evaluating the results of the group 1 based on clinical and ethological examinations, the values of impedance of vaginal mucosa and progesterone levels (Tab. I), the functional maturity of sexual organs in heifers were determined. No significant differences were found while compared the luteolytic effects between D-cloprostenol in the Remophan preparation and the conventional mixture of optically active forms of Oestrophan. All methods used confirm the functional maturity of sexual organs (including a response to prostaglandin analogues administered) in heifers 11-12 month old. The values of impedance of vaginal mucosa varied during oestrus in some heifers and this fact is to be taken into account in practice.(ABSTRACT TRUNCATED AT 250 WORDS)