Effects of dietary protein level on muscle cellularity and flesh quality in Atlantic salmon with particular reference to gaping

Growth performance, muscle cellularity and flesh quality were investigated in Atlantic salmon (Salmo salar L.) fed either of two diet ranges [high protein (HP), or low protein (LP)], which differed in digestible protein/digestible energy ratios but were of equivalent digestible energy content (21.4 MJ kg⁻¹ wet weight). Smolts from an early maturing (Lochy) and a late maturing (Mowi) strain were PIT-tagged and reared together in duplicate 5×5×5-m sea cages for each diet. The Lochy and Mowi fish were harvested in May and August, respectively, after 417 and 515 days in seawater. The average body weight of fish in each cage at harvest was in the range 3.8–5.4 kg, with no significant difference between diets. The total cross-sectional area of white muscle and the number and diameter of muscle fibres was determined at the level of the first dorsal fin ray. The distribution of muscle fibre diameters was investigated using nonparametric smoothing and bootstrapping techniques. Diet had no effect on fibre size distribution or fibre number in the Mowi strain, and small but significant effects for the Lochy strain. At harvest, in Lochy salmon of average fork length 69 cm there were around 15% more fibres in fish fed the HP than LP ratio diets. However, the 50th percentile of fibre diameter was 20% greater in fish fed the LP than HP diets, such that the total muscle cross-sectional area was similar. The lipid content (14.1–15.3% wet mass), astaxanthin pigment concentration (7.0–8.5 mg kg⁻¹ wet mass) and colour (RocheSalmoFan™ and Minolta Chromatometer readings) of the flesh were similar for both strains and diets. There was no significant difference in the average muscle fibre density between strains and diet, which varied between 60 and 140 fibres mm⁻² muscle cross-sectional area. Gaping during processing of the fillet was in part related to muscle cellularity. Little or no gaping was observed in any fish with a fibre density in excess of 95 fibres mm⁻² muscle. It was concluded that individual variation in fibre density is important in the development of gaping, but that muscle cellularity and flesh quality are relatively insensitive to the protein to energy ratio in the diet over the range studied.     

The effects of temperature and diet on the survival, growth and food uptake of aquarium-held postpueruli of the rock lobster Jasus lalandii

Aquaculture of the rock lobster Jasus lalandii has been considered, but is hindered by a paucity of knowledge about conditions that promote yields. This study investigated the influences of temperature and diet on the growth of aquarium-held postpueruli of J. lalandii. First, postpueruli (11.5±0.2 mm CL) were exposed to temperatures spanning 12–24 °C for a total time period of 77 days, while being given a constant diet of mussel flesh. Under these conditions, intermoult period (IMP) was longest at 12 °C (50.6±1.2 days) and at 24 °C (>57 days), and shortest at 18 °C (35.5±1.1 days). Growth increments (GI) were large at 12–18 °C, smaller at 21 °C and negative at 24 °C. Survival was 100% at 12–16 °C, above which mortalities rose to 70% at 24 °C. Food consumption, body mass and condition all peaked at 18 °C. Thus, growth was optimal at 18 °C, but survival greatest at 12–16 °C.

Second, diet-controlled experiments examined the effects of three different diets (blue mussel, commercial shrimpfeed or an alternation of the two) on survival, growth (IMP and GI) and food uptake of postpueruli (11.0±0.3 mm CL) held at 18 °C for a total time period of 77 days. Feeding rate, average growth, body mass and condition were all highest on the mussel diet, and lowest on the shrimpfeed, and the postpueruli consumed more mussel flesh than shrimpfeed. There was little difference in survival of postpueruli subjected to the three diet treatments.

A diet of exclusively blue mussel yielded higher growth, body mass, condition and food uptake than a diet of either shrimpfeed alone or an alternation of mussel and shrimpfeed. The postpueruli acclimated well to culture conditions and survived on a diet of artificial pellets, thus showing good potential for mariculture. On the present evidence, greatest returns are likely at 16–18 °C and with a diet of mussel flesh.     

Intensive rearing system for fish larvae research: I. Marine fish larval rearing system

Larvae nutrition and in general larvae culture is considered to be the ‘bottle neck’ for marine finfish culture. Fish larvae rearing experiments investigating nutritional factors or rearing protocols are carried out in various systems, from small beakers to very large commercial tanks, making it difficult to compare data across systems.

A continuous supply of live or dry feeds and a controlled environment, i.e. temperature, filtration, photoperiod, oxygen and pH, are essential for any experimental or commercial system. These environmental factors are best controlled automatically in order to minimize variations between tanks. However, only a few automatic systems have been developed for marine finfish hatcheries.

An experimental larval rearing system was developed to reduce variability amongst tanks (due to manual feeding and other parameters) and enhance control of environmental parameters while reducing the workload. The system includes 24 conical tanks with the option of either an up-welling or bottom draining flow through water delivery system. The inlet water passes through a gas exchange column that saturates the water with dissolved oxygen and stabilizes the pH. The system was originally designed for nutritional experiments using formulated feeds. The use of an up-welling water inlet method extends the suspension time of inert particles in the water column and also helps to suspend very small or passive swimming larvae. However, when the system is used to grow-on larvae or juvenile fish it can easily be switched to bottom draining to provide self-cleaning water dynamics for high organic loads.

A unique outlet filter was developed that eases the daily routine of replacing screens when enriched live food is used. This filter can be exchanged with a screened standpipe and outlet surface skimmer when the bottom draining flow characteristics are engaged.

The system is fully controlled by a single programmable logic controller (PLC). The PLC controls the light intensity, photoperiod, dimming time, live food and algae pumping intervals, substantially reducing labor requirements.     

Lime pelleting inoculated serradella (Ornithopus spp.) increases nodulation and yield

Lime pelleting of the inoculated seed is recommended for most pasture legume species to improve survival of the rhizobia on the seed and to counter deleterious effects of soil or fertiliser acidity on rhizobial numbers. Except for New South Wales, lime pelleting is specifically not recommended for serradella (Ornithopus spp.). Our objectives were to evaluate effects of lime pelleting on bradyrhizobial numbers on seed, and nodulation and growth of the serradella plants. Three experiments are reported at two acid-soil sites in northern New South Wales involving four cultivars of yellow serradella (Ornithopus compressus) and Bradyrhizobium sp. (Lupinus) strains WSM471 (current inoculant strain) and WU425 and WSM480. Lime pelleting increased bradyrhizobial numbers on seed, 24 h after inoculation, by an average of 90%. Similarly, lime pelleting increased nodulation and shoot dry matter of the inoculated plants by an average of 57 and 28%, respectively. The three strains were similar in effects on plant growth. Relative values for shoot dry weight, averaged over sites, were 100 for WSM471 and 98 for both WU425 and WSM480. Our results confirmed previous research that lime pelleting inoculated serradella seed was not deleterious to survival of the bradyrhizobial inoculum, and showed that it could result in enhanced symbiotic activity of the inoculum in some instances. We recommend lime pelleting of serradella and that WSM471 remain the inoculant strain.     

成年蓝孔雀日粮代谢能的研究

选用 5只雄性成年蓝孔雀 ,用A、B、C三种不同能量水平的颗粒日粮分期进行消化代谢试验 ,以探讨适宜的日粮代谢能水平、日粮能量水平与采食量的关系。结果表明 :蓝孔雀日粮表观代谢能分别为 :(1132 7± 5 0 8.5 4 )kJ/kg、(1180 7.6± 2 85 .17)kJ/kg、(1182 3.88± 84 4 .73)kJ/kg ,蓝孔雀对日粮能量的表观消化利用率各期间差异不显著 (P >0 .0 5 ) ;随着日粮能量浓度的提高 ,蓝孔雀对日粮干物质的采食量降低     

二次制粒加工断奶过渡料对早期断奶仔猪生长性能的影响

选用360头21日龄早期断奶仔猪平均分为4组,按制粒工艺、原料膨化预处理不同设计2因素2水平试验,研究二次制粒加工断奶过渡料对早期断奶仔猪生长性能的影响。结果显示:采用二次制粒工艺及膨化玉米、膨化豆粕原料的处理4仔猪,断奶后第一周,有最大的采食量(P<0.05);试验全期断奶14 d中,处理组4仔猪平均日增重最大,生长性能最好。血清尿素氮测定结果显示:断奶后第7天,处理组4仔猪血清尿素氮显著低于其他三组。断奶后第14天,处理组4仔猪血清皮质醇显著低于处理1组。此外,试验全期四个处理组仔猪血清总血糖无显著差异(P>0.05)。表明,在选择膨化玉米与膨化豆粕优质饲料原料的基础上,采用二次制粒工艺,尤其是先将鱼粉与膨化玉米、膨化豆粕进行第一次高温制粒,对降低仔猪断奶应激,改善生长性能有良好的效果。     

不同包衣剂对小麦生长发育及生产潜力的影响

研究了五种包衣剂对小麦的生长发育动态及经济性状的影响。各个处理对小麦的生长发育和物质积累均有促进作用,在优化株高、穗长、穗数、株粒数、粒重等经济性状方面取得明显效果。其中三个处理分别比对照增产10.6％,9.3％和9.0％,达显著水平。包衣剂的作用机理有待于进一步探讨。     

Use of glargine and lente insulins in cats with diabetes mellitus

The goals of this study were to compare the efficacy of once-daily administered Glargine insulin to twice-daily administered Lente insulin in cats with diabetes mellitus and to describe the use of a high-protein, low-carbohydrate diet designed for the management of diabetes mellitus in cats. All cats with naturally occurring diabetes mellitus were eligible for inclusion. Baseline testing included a physical examination, serum biochemistry, urinalysis and urine culture, serum thyroxine concentration, and serum fructosamine concentration. All cats were fed the high-protein, low-carbohydrate diet exclusively. Cats were randomized to receive either 0.5 U/kg Lente insulin q12h or 0.5 U/kg Glargine insulin q24h. Re-evaluations were performed on all cats at weeks 1, 2, 4, 8, and 12, and included an assessment of clinical signs, physical examination, 16-hour blood glucose curve, and serum fructosamine concentrations. Thirteen cats completed the study (Lente, n = 7, Glargine, n = 6). There was significant improvement in serum fructosamine and glucose concentrations in all cats but there was no significant difference between the 2 insulin groups. Four of the 13 cats were in complete remission by the end of the study period (Lente, n = 3; Glargine, n = 1). The results of the study support the use of once-daily insulin Glargine or twice-daily Lente insulin in combination with a high-protein, low-carbohydrate diet for treatment of feline diabetes mellitus.     

饲料对东北林蛙蝌蚪生长发育影响的研究

2008年3月29日～5月26日,在佳木斯市某东北林蛙养殖场,采用2组饲料饲喂东北林蛙蝌蚪,蝌蚪分为A组和B组。结果表明：饲喂T_1组饲料的蝌蚪41期和46期时的体重、体长和尾长明显大于饲喂T_2组饲料的蝌蚪;各组蝌蚪的成活率均在95%以上,各组蝌蚪完成变态的时间差异不显著;T_2组饲料的利用率要低于T_1组。