Some Factors Affecting Variation in Milk Yield in Crossbred Dairy Cows on Smallholder Farms in North-East Tanzania

A 2-year longitudinal survey was carried out to investigate factors affecting milk yield in crossbred cows on smallholder farms in and around an urban centre. Sixty farms were visited at approximately 2-week intervals and details of milk yield, body condition score (BCS) and heart girth measurements were collected. Fifteen farms were within the town (U), 23 farms were approximately 5 km from town (SU), and 22 farms approximately 10 km from town (PU). Sources of variation in milk yield were investigated using a general linear model by a stepwise forward selection and backward elimination approach to judge important independent variables. Factors considered for the first step of formulation of the model included location (PU, SU and U), calving season, BCS at calving, at 3 months postpartum and at 6 months postpartum, calving year, herd size category, source of labour (hired and family labour), calf rearing method (bucket and partial suckling) and parity number of the cow. Daily milk yield (including milk sucked by calves) was determined by calving year (p < 0.0001), calf rearing method (p = 0.044) and BCS at calving (p < 0.0001). Only BCS at calving contributed to variation in volume of milk sucked by the calf, lactation length and lactation milk yield. BCS at 3 months after calving was improved on farms where labour was hired (p = 0.041) and BCS change from calving to 6 months was more than twice as likely to be negative on U than SU and PU farms. It was concluded that milk production was predominantly associated with BCS at calving, lactation milk yield increasing quadratically from score 1 to 3. BCS at calving may provide a simple, single indicator of the nutritional status of a cow population.     

The feed value in growing pigs of a new cultivar of field beans (Vicia faba L.) supplemented with DL-methionine or DL-methionine-hydroxyanalog

Investigations in growing pigs on the feeding value of a new cultivar of field beans (Vicia faba L.) supplemented with DL -methionine or DL -methionine-hydroxyanalogue
A basal control mixture of barley, soy bean meal and soy bean oil was replaced by 25% of the new field bean-cultivar `Divine' and the resulting two mixtures were supplemented with minerals, trace elements, vitamins and amino acids according to the ideal protein concept. The control diet was adjusted with DL -methionine ( DL -Met), the field bean mixture either with DL -Met or DL -methionine-hydroxyanalogue ( DL -MHA) assuming biological equivalence on a molar basis for both supplements. The three experimental diets were fed to growing pigs (35–40 kg bwt.). Spontaneous urine samples were analysed separately for determining parameters that characterize the acid-base status of the pigs. There were no significant differences between experimental groups in nutrient digestibilities. The level of bacterially fermentable substances was increased in the diets containing field beans. The field beans contained 14 mg ME/kg DM. There were no significant (p < 0,05) differences in N- and mineral-retentions (Ca, P, Na, K) between the treatments. The stronger alkalinity found in urine after feeding the field bean mixtures resulted from a higher electrolyte balance of the diet.     

实验肝片吸虫感染对大鼠机体自由基代谢影响的研究

通过大鼠感染肝片吸虫复制感染模型 ,研究肝片吸虫感染后血清抗氧化功能的变化。 60只大鼠随机分成感染组和对照组 ,每组 30只。感染组大鼠一次口服 2 5个囊蚴 ,对照组不感染。于感染前 (0周 )和感染后 (1 ,3,5,7,9周 )采集血样 ,检测感染后谷胱甘肽过氧化物酶(GSH Px)、超氧化物歧化酶 (SOD)、过氧化物酶 (CAT)活性和丙二醛 (MDA)含量的变化。结果表明大鼠感染肝片吸虫后 ,感染组血清中GSH Px先升高后下降 ,SOD活性无明显变化 ,CAT活性在感染后下降 ,MDA含量在前 5周变化不明显 ;说明自由基参与了肝片吸虫病的发病过程     

IPM Strategies and Their Dilemmas Including an Introduction to www. eurowheat.org

Information about disease management in winter wheat （Triticum aestiva） in eight European countries was collated and analysed by scientists and extension workers within the European Network for the Durable Exploitation of Crop Protection Strategies （ENDURE）. This included information about specific disease thresholds, decision support systems, host varieties, disease prevalence and pathogen virulence. Major differences in disease prevalence and economic importance were observed. Septoria tritici blotch （Mycosphaerella graminicola） was recognized as the most yield reducing disease in countries with intensive wheat production, but also rust diseases （Puccinia striiformis and Puccinia triticina）, powdery mildew （Blumeria graminis） and Fusarium head blight （Fusarium spp.） were seen as serious disease problems. Examples of current integrated pest management （IPM） strategies in different countries have been reported. Disease management and fungicide use patterns showed major differences, with an average input equivalent to 2.3 full dose rates （TFI） in the UK and a TFI of 0.6 in Denmark. These differences are most likely due to a combination of different cropping systems, climatic differences, disease prevalence, and socio-economic factors. The web based information platform www.eurowheat.org was used for dissemination of information and results including information on control thresholds, cultural practices which can influence disease attack, fungicide efficacy, fungicide resistance, and pathogen virulence, which are all elements supporting 1PM for disease control in wheat. The platform is open to all users. The target groups of EuroWheat information are researchers, advisors, breeders, and similar partners dealing with disease management in wheat.     

Crystal structure of human ZAG, a fat-depleting factor related to MHC molecules

Zn-alpha2-glycoprotein (ZAG) is a soluble protein that is present in serum and other body fluids. ZAG stimulates lipid degradation in adipocytes and causes the extensive fat losses associated with some advanced cancers. The 2.8 angstrom crystal structure of ZAG resembles a class I major histocompatibility complex (MHC) heavy chain, but ZAG does not bind the class I light chain beta2-microglobulin. The ZAG structure includes a large groove analogous to class I MHC peptide binding grooves. Instead of a peptide, the ZAG groove contains a nonpeptidic compound that may be implicated in lipid catabolism under normal or pathological conditions.     

Hg、As、Cr、Cd在食物链中迁移规律的研究

采用五分法采集农灌水 (工业废水 )、农田土壤、农作物和畜禽产品样品 ,并检测其中重金属元素汞( Hg)、砷 ( As)、铬 ( Cr)和镉 ( Cd)的含量。结果表明 ,4种重金属元素在农灌水和土壤中的含量由低到高分别依次为Hg相似文献   

Potassium induced improvement of yield response in barley exposed to soil water stress

Summary The interaction of different K status of barley plants (Hordeum vulgare, L.) and water stress on yield and water relations was studied. The plants which were cultivated outdoor in pots and supplied with 0.8, 5.0, 8.5 or 12.0 g K per pot, as KCl, were subjected to increased soil water stress during the early grain filling stage.The water content of the flag leaf tissue was significantly increased from 3.1 to 4.1 g H₂O/g D.M. (dry matter) by K application resulting in maintenance of similar leaf osmotic potentials (–1.5 MPa) at all K levels prior to onset of water stress (Table 2). At the lowest K level Ca contributed essentially to maintenance of the cell osmotic potential (Fig. 2).In fully watered plants grain yield at the lowest K level was reduced 20% (Fig. 5 a) due to a decrease in the number of tillers with ears per plant (Fig. 5 b) and to early commencement of maturity processes (Table 3).Water stress caused grain yield reductions between 15 and 50%. However, by increase of K application yield was maintained to the greatest degree in high K plants (Fig. 5 a) due to improved water status in these plants during the drying cycle (Fig. 4). The production of above ground dry matter (top D.M.) during the grain filling period and the grain yield were highly correlated with the leaf water content at the end of the drying cycles (Fig. 6). The greater yield in high K plants was associated with prolongation of the grain filling period by up to 7 days (Table 3) and with an increase in grain weight by up to 20% (Fig. 5 b) as compared with low K plants. Preanthesis reserves contributed up to 52% of grain yield at low K levels (Fig. 5 c) reducing differences in grain yield between the K levels.Abbreviations RWC predawn relative water content - predawn leaf osmotic potential - WUE water use efficiency - R preanthesis reserves - ear D.M. increase in ear D.M. during the grain filling period - top D.M. increase in top D.M. during the grain filling period - SD standard deviation - LSD least significant difference