放牧补饲对肉用犊牛生长发育与经济效益的影响

[目的]研究在放牧补饲条件下不同品种肉牛的早期生长发育与经济效益。[方法]选择3月龄断奶新褐杂牛(新疆褐牛与本地牛)、安杂牛(安格斯与本地牛)、荷斯坦牛、土种牛31头,按品种分组开展夏草场放牧补饲试验。[结果]安杂牛、荷斯坦牛、新褐杂牛和土种牛补饲日增重分别为0.51、0.55、0.56、0.25 kg/d,安杂牛、荷斯坦牛、新褐杂牛的日增重与土种牛相比差异极显著(P0.01)。新褐杂牛、荷斯坦牛、安杂牛的放牧补饲效果较土种牛好,新褐杂牛、荷斯坦牛、安杂牛和土种牛的投入产出比分别为1∶2.32、1∶2.29、1∶2.12和1∶1.02,放牧补饲经济效益明显。[结论]早期断奶对后期放牧补饲肉牛的生长发育具有促进作用。     

Major compositional units of the moon: lunar prospector thermal and fast neutrons

Global maps of thermal and fast neutron fluxes from the moon suggest three end-member compositional units. A high thermal and low fast neutron flux unit correlates with the lunar highlands and is consistent with feldspathic rocks. The South Pole-Aitken basin and a strip that surrounds the nearside maria have intermediate thermal and fast neutron flux levels, consistent with more mafic rocks. There appears to be a smooth transition between the most mafic and feldspathic compositions, which correspond to low and high surface altitudes, respectively. The maria show low thermal and high fast neutron fluxes, consistent with basaltic rocks.     

Dietary Effects on Sperm Quality of Litopenaeus vannamei Broodstock

A 56‐d feeding trial was conducted to investigate the effect of diet on sperm quality of Pacific white shrimp Litopenaeus vannamei broodstock. Dietary treatments consisted of a combination of 75% dry maturation diet and 25% fresh‐frozen squid (dry‐weight basis). Supplemental nutrients of the maturation diet were selectively deleted and replaced with wheat starch to produce the following treatments: 1) 75% basal maturation diet plus 25% squid (control); 2) 75% maturation diet without supplemental vitamins plus 25% squid; 3) 75% maturation diet without supplemental cholesterol and phospholipids plus 25% squid; 4) 75% maturation diet without supplemental astaxanthin plus 25% squid; and 5) a fresh diet composed of 60% squid and 40% Maine bloodworms. Shrimp fed the control diet and the diet without supplemental astaxanthin had significantly higher mean (± SEM) change in sperm count (4.6 ± 3.2 million sperm cells and 2.9 ± 2.5 million sperm cells, respectively), with respect to baseline (8.7 ± 1.0, 6.4 ± 1.0, 9.0 ± 1.3, 6.6 ± 0.7, and 6.0 ± 0.8 million sperm cells for treatments 1, 2, 3, 4, and 5, respectively), than shrimp fed the diet without supplemental vitamins (‐1.7 ± 2.6 million sperm cells), but not significantly higher than those of shrimp receiving the diets without supplemental cholesterol‐phospholipids (1.2 ± 2.5 million sperm cells) and the fresh diet (1.3 ± 1.6 million sperm cells). Dietary deficiencies also were reflected in weight gain of shrimp fed the diet without supplemental vitamins (‐2.0 g) and the fresh diet (‐0.8 g). which were significantly lower than weight gain of shrimp fed the control diet (1.1 g) and the diet without supplemental cholesterol‐phospholipids (0.8 g). No significant differences were detected among treatments for percentage of abnormal sperm and survival data. Results demonstrated a significant effect of diet on reproductive quality of male L. vannamei and indicated that the typical combination of fresh‐food organisms used is not nutritionally optimal for male broodstock.     

The influence of diel period on fish assemblage in the unstructured littoral of reservoirs

Abstract Diel changes in littoral fish assemblage were studied in four reservoirs in the Czech Republic (Central Europe). The sampling was performed by beach seining in an unstructured littoral zone. Perch, Perca fluviatilis L., roach, Rutilus rutilus (L.), bream, Abramis brama (L.), carp, Cyprinus carpio L., ruffe, Gymnocephalus cernua (L.), pikeperch, Sander lucioperca (L.), eel, Anguilla anguilla (L.) and A. brama × R. rutilus hybrids exhibited higher densities at night. Only bleak, Alburnus alburnus (L.) exhibited higher densities during the day. The number of species was higher in night hauls, and mean body size of roach and bleak was also higher at night. Diel changes in fish densities resulted in the change in species composition between day and night. The study has implication for the sampling design to assess littoral fish assemblages using beach seine netting and recommends night sampling for a representative assessment or sampling during both diel periods for a robust assessment.     

Irrigation of paddy soil with industrial landfill leachate: impacts in rice productivity,plant nutrition,and chemical characteristics of soil

Treated industrial effluents have high levels of nutrients and dissolved organic matter. The irrigation of rice by flooding can increase nutrient uptake and grain yield. Therefore, this study evaluated the nutrient contents in the shoots and grain of the rice crop and also the chemical of the soil after irrigation of the crop with leachate of the treated industrial effluent. A greenhouse experiment was conducted using pots filled with 20 kg of soil in a randomized block design with three replications. The treatments consisted of control (irrigation with distilled water) and four concentrations of the leachate (25, 50, 75, and 100 %) for irrigation. At the end of the experiment, the nutrient contents in tissues of rice plants, sterility of spikelets, and grain mass were evaluated. Results showed that irrigation with the leachate at 25 % content increased the macro- and micronutrients’ concentrations in the shoot biomass and grain, except for potassium and iron. Irrigation with the industrial leachate decreased tillering and grain yield; however, it increased chlorophyll content, sterility of spikelets, and sodium intake at this leachate concentration. The potassium and sodium levels and the electrical conductivity values of soils irrigated with treated industrial leachate were increased. The use of the treated leachate from industrial effluents is an alternative that reuses the nutritional load, but the volume of leachate should be limited and monitored to prevent the sodicity in the soil and problemsdue to eutrophication.     

Tail Muscle Free Amino Acid Concentration of Pacific White Shrimp,Litopenaeus vannamei,Fed Diets Containing Protein‐bound versus Crystalline Amino Acids

Tail muscle tissue free amino acids (FAA) concentration is reported for subadult (4.3 g) Litopenaeus vannamei fed diets containing only protein‐bound amino acids, crystalline lysine as a supplement to protein‐bound lysine, and only crystalline amino acids (CAA). FAA were determined in shrimp at 0.00, 0.25, 0.5, 1, 2, 4, and 8 h postfeeding. Highest total tissue concentrations of essential amino acids and individual amino acids were typically observed 4 h postfeeding for shrimp fed intact and crystalline lysine‐supplemented feeds. Those shrimp offered diets containing only CAA showed no tissue maxima. Similar uptake patterns for lysine shown by shrimp fed the intact and crystalline lysine‐supplemented diet indicate the potential use of small amounts of crystalline lysine in shrimp feeds.