Effects of extrusion processing on digestibility of peas, lupins, canola meal and soybean meal in silver perch Bidyanus bidyanus (Mitchell) diets

Two experiments were conducted to investigate effects of processing on apparent digestibility coefficients (ADCs) of legumes and oilseeds for juvenile silver perch, Bidyanus bidyanus (～49 g). The first experiment evaluated interactive effects of ingredients (lupins or field peas), processing (whole seed; hulls on or hulls off) and extrusion cooking (raw or extruded) on ADCs for juvenile silver perch (～4 g fish^?1). The second experiment was a three‐fixed‐factor anova designed to evaluate interactive effects of ingredients (soybean meal or canola meal), extrusion cooking (raw or extruded) and inclusion content (30% or 50% of the diet) on ADCs for juvenile silver perch (～4 g fish^?1). Lupin protein was more digestible than that of peas (ADC for crude protein 91% vs. 85% for peas) but the organic matter was less digestible (ADC for organic matter 50% vs. 67% for peas). Dehulling lupins significantly improved ADCs for all indices (dry matter, organic matter, energy and crude protein), but extrusion had no effect because lupins do not contain starch or heat‐labile anti‐nutrients. Conversely, for starch‐rich peas that contain heat‐labile trypsin inhibitors, both dehulling and extrusion significantly improved ADCs. Digestibility of soybean meal was much higher than that of canola meal. For soybean meal, neither processing, content nor their interaction affected digestibility but extrusion improved ADCs for dry matter, organic matter and energy but there was an interaction with content. Although higher overall, digestibility for these indices declined with increasing content for extruded product while there were only minor effects of inclusion for raw product. Benefits of extrusion were attributed to reductions in anti‐nutrients, including phytic acid. For canola, there were no interactions between extrusion and content for any ADC. Increasing content reduced ADCs for crude protein, dry matter and organic matter but did not effect energy. Surprisingly, extrusion of canola also reduced digestibility for all ADCs. Dehulling improved both lupins and peas. Crude protein for all ingredients was well digested with ingredients ranked: lupins>soybean meal>peas>canola meal. Energy digestibility was best for soybean meal and worst for lupins. Extrusion greatly improved digestibility of peas and to a lesser extent soybean meal, gave no benefits to lupins and was detrimental for canola.     

几个新光温敏水稻核不育系在南京自然条件下的育性表现

两系法超级杂交稻的育种实践表明,发展两系法杂交稻,光温敏核不育系是基础和关键。中国每年都有新的光温敏核不育系作为育种材料进入配组利用,但真正投入生产应用且产生经济和社会效益的并不多[1~3]。据杨远柱等[4]统计,在82个通过省级技术鉴定的光温敏不育系中,只有15个不育系     

Microsomal oxidase activities in relation to age and chlorcyclizine induction in American cockroach,Periplaneta americana,fat body,midgut and hindgut

Female adult American cockroaches, Periplaneta americana L., showed definite age-dependent changes in levels of activity of the microsomal mixed-function oxidases. Cytochrome P-450 levels, EPN-detoxication, and p-nitroanisole O-demethylation activities were very low in young adult insects but increased steadily reaching a natural peak at about 100 days in fat body and at about 90 days in midgut and hindgut. The activities then declined rapidly reaching levels of young insects at about 130 to 140 days of age. NADPH-neotetrazolium-reductase activity was high in young insects, declined later in adult life, and returned to a peak at about 100 days.Injections of chlorcyclizine, a known microsomal enzyme inducer, significantly increased levels of cytochrome P-450, EPN-detoxication, p-nitroanisole O-demethylation, and NADPH-NT-reductase activities in young cockroaches. The drug injections were effective, however, only before the natural activity peak was reached. Beyond this point the injections had no inductive effect indicating that the microsomal oxidases in this insect are uninducible when normal enzyme levels are falling.NADPH-NT-reductase activity in male cockroaches, while being somewhat higher than in females, showed a similar age-dependent curve with the peak occurring at about 120 days.Age-dependent carbaryl resistance in male and female insects tended to follow levels of the microsomal oxidase activities. Fifty to 60-day-old insects, however, tended to be more resistant to the insecticide than microsomal enzyme levels would indicate.RNA levels of normal female insects showed age-dependent curves similar to those of the microsomal enzyme activities, being low in young adults and reaching a peak at about 100 days. Chlorcyclizine injections had little or no effect on total microsomal RNA levels.     

Influence of inorganic and organic fertilization on soil microbial biomass, metabolic quotient and heavy metal bioavailability

 We studied the long-term effects (12 years) of municipal refuse compost addition on the total organic carbon (TOC), the amount and activity of the microbial biomass (soil microbial biomass C, B_C and metabolic quotient qCO₂) and heavy metal bioavaiability in soils as compared to manuring with mineral fertilizers (NPK) and farmyard manure (FYM). In addition, we studied the relationships between among the available fraction [Diethylenetriaminopentacetic acid (DTPA) extractable] of heavy metals and their total content, TOC and B_C. After 12 years of repeated treatments, the TOC and B_C of control and mineral fertilized plots did not differ. Soils treated with FYM and composts showed a significant increase in TOC and B_C in response to the increasing amounts of organic C added. Values of the B_C/TOC ratio ranged from 1.4 to 2, without any significative differences among soil treatments. The qCO₂ increased in the organic-amended soil and may have indicated microbial stress. The total amounts of metals in treated soils were lower than the levels permitted by the European Union in agricultural soils. DTPA-extractable metals increased in amended soils in response to organic C. A multiple regression analysis with stepwise selection of variables was carried out in order to discriminate between the influence exerted on DTPA-extractable metals by their total content, TOC and B_C. Results showed that each metal behaved quite differently, suggesting that different mechanisms might be involved in metal bioavailability Received: 31 October 1997     

Effects of different arginine/lysine level on growth performance,body composition and digestive enzyme activity of Macrobrachium rosenbergii

Given the universal presence of antagonism between arginine and lysine, determining the optimal dietary arginine/lysine level is of great importance. In this study, eight diets were formulated to contain different arginine/lysine level, followed by a 9‐week feeding trial with shrimps of 2.10 ± 0.01 cm in length and 0.38 ± 0.02 g in weight to determine the effect of dietary arginine/lysine level on growth performance, body composition and enzyme activity. The results showed that the Diet 6 (arginine/lysine level of 29.4/21.0 g/kg) group had significantly higher weight gain rate, and specific growth rate than the control group and most of the other groups (p < .05) did. Similarly, the retention efficiency of arginine and lysine in the Diet 6 group was significantly higher than the control group and most of the other groups (p < .05). Moreover, most digestive enzymes had higher activity levels in the Diet 6 group, and evident antagonism between dietary arginine and lysine was detected. In summary, dietary arginine/lysine level of 29.4/21.0 g/kg produced the best growth performance, suggesting that a better growth performance in Macrobrachium rosenbergii culture can be obtained by adjusting the dietary arginine/lysine level.     

根瘤菌对厚荚相思组培苗的效应

采用不同根瘤菌接种到厚荚相思组培苗上,探讨不同根瘤菌对厚荚相思组培苗的影响,结果表明:不同根瘤菌对厚荚相思组培苗的高生长、生物量、叶绿素含量和结瘤率均有明显的作用,表现出根瘤菌与植物种存在不同的亲和关系;根据苗木各项指标的测定结果,筛选出HO6和HA4优良菌株.     

Prevalence and risk factors for anti-Toxoplasma gondii antibodies in goats of the Seridó Oriental microregion, Rio Grande do Norte state, Northeast region of Brazil

The prevalence and risk factors for anti-Toxoplasma gondii antibodies were investigated in goats of the Seridó Oriental microregion, Rio Grande do Norte state, Northeast region of Brazil. Three hundred and sixty-six blood samples from goats collected by jugular venopuncture were used. For the serologic diagnosis of Toxoplasma gondii infection, the indirect fluorescent-antibody test (IFAT) with cut-off value 1:64 was carried out. The prevalence of anti-T. gondii antibodies was 30.6% [95% CI=25.9-35.6%] with titers ranging from 1:64 to 1:16,384. The multivariate logistic regression analysis showed that the risk factors associated to anti-T. gondii antibodies were presence of cats in the herd, extensive/semi-intensive management systems and lack of mineral supplementation.