仔猪渗出性皮炎的诊治

1999年6月初,朝阳县柳城开发区某猪场的4窝37头仔猪发生了一种以皮肤病变为主的疾病,表现为皮肤呈粘湿的油脂状渗出物,渗出物和尘埃、皮屑及垢物形成龟背的痴皮,耳根、眼周围、肘后较严重,并有难闻的臭味。病猪精神沉郁、厌食、脱水及战栗,仔猪发病4d内相继死亡7头。据以上症状及流行病学情况疑为仔猪渗出性皮炎。剖检变化,无特异的剖检病变。细菌学检查,从结合膜囊中和病变表皮涂片中发现葡萄球菌,进一步经实验室分离培养确诊为葡萄球菌感染。回治疗1．1用炎克星注射液（吉林长白鹿业股份有限公司兽药厂生产）,O．lmL／kg体重肌…     

青藏高原东缘草地生态系统动态定位监测与可持续发展发素研究——Ⅱ高寒草甸草地生态系统植物群落结构特征及物种多样性分析

通过对青藏高原东缘高寒草甸生态系统8个草地类型植物群落样地定位监测资料进行结构特征及物种多样性分析研究，结果表明，青藏高原东缘高寒草甸草地草群盖度大，物种丰富，但大多数草地多样性随退化程度的加重而降低，优良牧草所占比例不高，总的反映出退化演替的趋势，超载，鼠虫危害，人为干扰以及全球气候变化等因素是草地退化的主要原因。从群落结构特征来看，不同类型群落演替阶段依次为原生植被（Ⅵ，Ⅶ），轻度退化（Ⅰ，Ⅲ，Ⅳ，Ⅴ），重度退化（Ⅱ，Ⅷ），群落物种丰富度指数（S）依次为Ⅲ＞Ⅴ＞Ⅵ＞Ⅶ＞Ⅰ＞Ⅳ＞Ⅱ＞Ⅶ；物种多样性指数依次为Ⅵ＞Ⅴ＞Ⅶ＞Ⅲ＞Ⅰ＞Ⅱ＞Ⅷ＞Ⅳ，表现出原生植被的物种多样性指数明显高于不同退化程度的群落类型。因此，加大力度保持高原生态环境，尽快遏制草地退化趋势应为当务之急。     

甜菜二倍体新品种—包育201的选育

甜菜二倍体新品种--包育201，是系统选育的普通二倍体杂交种。该品种产量稳定，含糖率较高，抗褐斑病性强，对丛根病、黄化毒病有较强耐病性。在1995～1997年的自治区甜菜品种区域试验中，1996-1997两年达到新品种标准，其块根产量、含糖率和产糖量两年平均比对照分别提高10.7%、0.73度和15.8%；在1998年的生产试验中，根产量、含糖率和产糖量分别比对照提高12.5%、0.6度和16.9%。     

Biometric parameters of ovaries in the Tsigai strain of sheep and their changes after administration of cloprostenol

The weight, length, width and volume of ovaries were determined as well as the number of follicles visible on the surface in relation to the presence of corpus luteum on the ovary in autumn period after Cloprostenol application. The ovaries of 43 sheep of the Tsigai breed were examined at the age of 2--4 years. The animals were divided into five groups. First group (I) was the control (n = 6). In the luteal phase of sexual cycle the animals of groups II to V were applied i. m. 125 micrograms of cloprostenol in Oestrophan inf. Spofa preparation. According to groups II (n = 8), III (n = 10), IV (n = 9), V (n = 10) the animals were killed at intervals of 24, 48, 72 and 120 hours (h) from the preparation application. The removed ovaries were fixed in 10% neutral formalin; after a 48-hour fixation they were weighed and their length and width were measured. Tertiary follicles visible on the surface were counted and measured. In group I we demonstrated the significantly higher weight of ovaries with corpus luteum (CL) as compared with ovaries without CL (P less than 0.001). The weight of ovaries with CL dropped significantly within 48 hours after cloprostenol application as compared with control (P less than 0.001) and the difference in the ovary weight according to CL incidence disappeared almost completely. In comparison with groups III and IV, the weight of ovaries in ewes of group V increased statistically significantly (P less than 0.01) on 5th day from the cloprostenol application. This finding is a result of development of new CL after a passed ovulation. The alterations in length, width and volume of ovaries were not so significant as those in weight. The number of surface follicles was very variable and the changes were not significant. The changes in the average size of follicles larger than 1 mm and of the largest follicles have shown that both parameters achieved significantly higher values in ovaries of the control group with present CL in comparison with ovaries without CL. The reduction of surface follicles after cloprostenol application seems to be connected with a possible operation on contractile structures of the external theca folliculi.     

Tillandsia spp.: Epiphytic weeds of trees and bushes

This paper comments on the increase of population of two species: Tillandsia recurvata (L.) Linne and Tillandsia aëranthos (Loisel) L.B. Smith (Bromeliaceae) in the La Plata area of Argentina. These small, oligotrophic, herbaceous plants were observed on many species of trees and bushes growing in the arboretum of the Faculty of Agronomy and in parks of the city. Such woody species are present in other areas of the country and would be susceptible to attack in the future.Both species grow initially on the branches of the trees and later colonise the whole host, causing abscission of the leaves and the death of the tree. Consistent with this finding, these epiphytes are considered specialised weeds of the host plant and preliminary results of this study demonstrate the presence of a natural inhibitor in crude extracts of the plants. At present, work is in progress to study its effect upon leaf abscission and the colonisation strategy related to damage upon host trees.     

The effect of dietary calcium concentration and particle size on performance, eggshell quality, bone mechanical properties and tibia mineral contents in moulted laying hens

1. A total of 72 H&;N Brown Nick laying hens, 76 weeks of age (moulted at 60 weeks of age), were randomly assigned into a 3?×?3 factorial arrangement with three limestone particle sizes and three dietary Ca concentrations (30, 36 and 42?g/kg Ca); with 8 replicates per treatments, and one hen (individual) per experimental unit.

2. Particle sizes of the limestone were: distributions smaller than 2?mm (Fine), between 2 to 5?mm (Medium), and larger than 5?mm (Large). The fine, medium and large limestone particles were all obtained from the same source, and sieve sizes used had screen sizes 2?mm and 5?mm.

3. The different concentrations of dietary Ca, particle size or interactions had no significant effect on egg production, egg weight, egg mass, feed intake or feed conversion ratio.

4. The concentrations of dietary Ca and particle sizes had no significant effect on egg breaking strength, eggshell as % by weight of whole egg or eggshell thickness. The interactions between Ca concentrations and particle sizes had a significant effect on eggshell breaking strength, but not on other parameters.

5. Different dietary particle sizes had no significant effect on the Ca, P and Mg mineral contents of eggshell. While the different concentrations of Ca in diets had a significant effect on the P content of eggshell, they had no significant effect on Ca and Mg contents.

6. Different dietary concentrations of Ca had a significant effect on shear stress, and Ca and Mg contents of tibiae, but not other parameters. Also, dietary particle sizes had a significant effect on shear stress and Ca contents of tibiae. The interaction between Ca concentrations and particle sizes had a significant effect on tibia shear force and Ca content.

7. According to the results of this study, moulted brown laying hens should be fed 36?g/kg Ca and a medium limestone particle size (2–5?mm) in the diet to maintain performance, eggshell and bone quality.     

Effect of maternal corticosterone on utilisation of residual yolk sac fatty acids by developing broiler embryo

1. Increased concentrations of maternal corticosterone are deposited into egg yolk under stress conditions. This experiment investigated the effect of maternal corticosterone on yolk and yolk sac fatty acid profiles of eggs and developing broiler embryos. 2. At 42 weeks of age, 200 broiler breeder females were randomly divided into two groups: maternal corticosterone (MC): 2 mg/hen/d of corticosterone dissolved in 1 mL of 99% ethanol and mixed in the individual daily feed for a 14 d period, and control: 1 mL of ethanol added to the individual daily feed. Hens were inseminated, and eggs were collected daily from d 3 of corticosterone feeding to d 14 and incubated. Fatty acid profiles of egg yolk and yolk sac were analysed before incubation and at 12, 14, 18 and 21 d of incubation. 3. Yolk corticosterone concentrations were greater in MC eggs. Before incubation, eggs from MC had lower DHA (22 : 6 n-3) but higher stearic (18 : 0) and dihomo-gamma linolenic (20 : 3 n-6 Cis 8,11,14) acid content compared with the control. 4. Higher concentrations of stearic (18 : 0), elaidic (18 : 1 tr n-9), eicosenoic (20 : 1 n-9), eicosadienoic (20 : 2 n-6), dihomo-gamma linoleic (20 : 3 n-6) and arachidonic (20 : 4 n-6) acids and lower concentrations of myristic (14 : 0), palmitoleic (16 : 1 n-7), linoleic (18 : 2 n-6) and DHA (22 : 6 n-3) were found at different periods of incubation in the residual yolk sac of MC than from controls. 5. The results suggest that the preferentially selective absorption of fatty acids is related to specific tissue requirements.     

Effect of season and photoperiod on the time of first postpartum ovulation in Awassi ewes

Seasonal differences in the resumption of postpartum ovarian activity, milk production and periparturient metabolic status were investigated in lactating non-suckling dairy Awassi sheep in two consecutive experiments. In Experiment 1, autumn-lambing (AL, n = 27) and spring-lambing (SL, n = 37) ewes were investigated. Ovarian activity was monitored by means of individual progesterone (P4) profiles from day 5 to day 100 post partum. Most of the AL dams (89%) ovulated till day 35 after parturition and became cyclic thereafter. Incidence of persistent corpus luteum (CLP) and short luteal phases (sCL) was frequent (18% and 29%, respectively) among non-conceiving dams. In contrast, only 24% of the SL ewes ovulated before day 35. P4 levels during the luteal phase were lower in cyclic animals, and the cycle was longer in SL than in AL animals. No CLP or sCL was detected in the spring-lambing group, and 61% of SL ewes remained acyclic till the end of the trial. Lactation length was significantly longer in SL dams than in AL ewes (P = 0.008). According to the plasma metabolites (BHB, NEFA) and metabolic hormones (insulin, IGF-I, thyroxine) examined, negative energy balance did not appear in any of the animals. However, seasonal differences were seen in IGF-I and thyroxine levels, which were higher in the SL dams. In Experiment 2, influence of additional lighting was studied in autumn-lambing ewes. The long-day photoperiod (LD, n = 23) group was exposed to artificial light from sunset till midnight (approx. 16 h light/8 h dark) from some weeks before the expected date of delivery in mid-September until the end of December. The control group (n = 25) experienced only natural daylength. The first postpartum ovulation tended to occur later in the LD animals than in the controls (P = 0.047). The lactation of the LD group tended to be longer (P = 0.061). NEFA, BHB, insulin, IGF-I and thyroxine levels did not differ between the groups. Conclusions: (i) The ovarian function of the Awassi population is seasonal under temperate continental climate conditions. (ii) The first postpartum ovulation of non-suckling, autumn-lambing dams may occur very early, even before the completion of uterine involution. (iii) Additional artificial lighting may delay the time of first postpartum ovulation in AL ewes. (iv) Postpartum negative energy balance is unlikely to occur in dairy Awassi ewes even in high-producing intensive systems.     

Prevalence and molecular mechanism of macrolide and lincosamide resistance in staphylococci isolated from subclinical bovine mastitis in Turkey

Macrolide and lincosamide (ML) resistance and the related resistance genes of staphylococci were assessed from cases of bovine subclinical mastitis. Of the 104 Staphylococcus aureus and 62 coagulase negative staphylococcus (CoNS) isolates, 26 (25%) and 12 (19.4%) were resistant to ML, respectively. While constitutive ML resistance phenotype accounted for 15.4% (16/104) of S. aureus and 8.1% (5/62) of CoNS, inducible ML resistance phenotype accounted for 2.9% (3/104) of S. aureus and 3.2% (2/62) of CoNS. Among erythromycin-resistant isolates, single or various combination of different resistance genes were detected. The results of this study showed that ML resistance was prevalent among staphylococci from subclinical bovine mastitis cases in Hatay, Turkey. Therefore, a continuous surveillance is necessary to minimise the spread of antimicrobial-resistant staphylococci.