江南白鹅消化器官的早期生长发育特点及其相关性研究

为探究江南白鹅消化器官早期生长发育特点,通过饲养试验研究江南白鹅消化器官的生长发育规律及其与体重的相关关系,以期为江南白鹅及其他中型白鹅的饲料科学配制和科学饲养参考。结果表明：①4周龄时,各消化器官的长度或重量与9周龄时比较,十二指肠、空肠和回肠的长度和重量均达80%以上,盲肠达69%,胃重量达63%,肝脏重量达56%。0—4周中,第1周各消化器官的指数增长率最高,均达66%以上。②4周龄时,江南白鹅的十二指肠长度、空肠长度、空肠重量和腺胃重量与9周龄时体重呈显著正相关（P＜0.05）;其他指标与体重相关性不显著（P>0.05）。③整个生长期,江南白鹅消化器官的生长发育集中于前4周,肠道优先发育,随后是胃部,再其次是肝脏。消化器官的生长发育高峰期在第1周,且速度大于同期体重。空肠早期的生长发育情况与体重生长相关性最强。     

The effects of variation in feed protein level on the culture of white shrimp, Litopenaeus vannamei (Boone) in low-water exchange experimental ponds

The present study was conducted to evaluate the effect of varying dietary protein level on pond water quality and production parameters of white shrimp Litopenaeus vannamei (Boone). Experimental units consisted of nine 400‐m² earthen ponds with a low water exchange. Two treatments were tested: treatment HP consisted of shrimp fed a high‐protein diet (40%) during the whole grow‐out, and treatment LP consisted of the use of a low‐protein diet for the complete farming period. No differences on any of the water quality parameters were observed among treatments. Excellent survival (over 85%) and feed conversion ratios (around 1.6), and acceptable growth (over 12 g) and biomass (from 1721 to 1793 kg ha^?1) were recorded in all experimental ponds. No significant differences in any of the production parameters were found among treatment groups.     

日粮赖氨酸水平对皖西白鹅繁殖力的影响

在日粮主要营养成份达标的基础上,通过调节赖氨酸水平0.49%、0.64%、0.79%,探讨其对皖西白鹅繁殖力的影响,结果表明:1赖氨酸水平影响产蛋量P<0.05,而不影响其它的繁殖力指标P>0.05;20.64%的赖氨酸水平最能体现皖西白鹅的繁殖性能。     

黄海北部发现的中华白海豚Ⅰ.外形和内脏器官的测定结果

中华白海豚(SousaChinensis)属于国家Ⅰ级重点保护野生动物,在中国主要分布于广西、海南、广东、香港、澳门、台湾、福建、浙江沿岸,向北可达长江口。2003年5月9日在黄海北部(北纬39°35′01″,东经122°51′50″),由于渔业生产误捕的中华白海豚,是迄今为止该种发现的最北记录,笔者报告了对该海豚的外形和内脏器官测定结果。     

Age‐dependent baseline values of faecal cortisol metabolites in the American mink (Neovison vison) under semi‐natural housing conditions

The welfare of an animal is ensured if it is able to fully satisfy its essential species‐typical needs in all functional aspects of behaviour. In mink, stereotypies and apathy, internal and/or external injuries as well as increased susceptibility to disease have been known to occur as a result of chronic stress. The non‐invasive method of analysing faecal cortisol metabolites (FCM) allows conclusions to be drawn about the stress level in the respective housing system. The objective of this study is to find out how the cortisol metabolites content in the faecal changes with increasing age of the mink under semi‐natural housing conditions. Thus, 40 American mink (Neovison vison) were housed in two outdoor enclosures imitating natural conditions. Throughout the entire study (13th to 32nd week of life), faecal samples were collected to measure cortisol metabolites. No differences in FCM concentrations between the two outdoor enclosures were found. In the young mink lower, less fluctuating FCM levels were found than in older animals. After the first faecal collection in the 13th/14th week of life, the level of metabolites decreased slightly (p = 0.032; 17th/18th week). From the 22nd/23rd week onwards until the 30th/31st week, shortly before the animals were pelted, continuously increasing concentrations were then measured. Increasing FCM levels with advancing age of the animals are probably attributable to the onset of sexual maturity and/or the respective season. This has to be taken into account in future studies using this method for assessing welfare and when comparing different mink housing systems.     

低盐水体南美白对虾与鲢鳙鱼混养的试验

在6口低盐淡水(盐度2～10)池塘中放养体长0 8～1 0cm的南美白对虾(Penaeusvan namei)(30万尾/hm2),其中三口塘再放养鲢(Hypophthalmichthysmolitrix)、鳙(Aristichthysno bilis)夏花(体长2 0～3 0cm)(1500尾/hm2,鲢:鳙=1:1)。鱼、虾分别精养90d和60d。混养池塘中对虾的成活率(24 6%)为单养池(9 1%)的2 7倍,产量(800 0±86 7)kg/hm2为单养池的3 2倍;鱼产量为(93 9±7 9)kg/hm2,鳙的出塘规格大于鲢,产量高于鲢。混养池塘水中氨氮、亚硝态氮和溶解氧含量低;透明度和活性磷含量高;pH值波动幅度小。     

Effect of feeding on the tissue free amino acid concentrations in rainbow trout (Oncorhynchus mykiss Walbaum)

This study investigates whether tissue free amino acid (FAA) pools in rainbow trout,Oncorhynchus mykiss (Walbaum), are altered following feeding and the relationships between the amount of food consumed and the FAA pool size. Trout were starved for 7 days to provide baseline data and then refed on day 8. Individual food intake was measured by radiography and the consumption of amino acids (AA) calculated from dietary protein consumption. Total FAA concentrations in the stomach, liver and white muscle were little changed at various times after the meal and this pattern was repeated for the majority of individual FAA. Overall, the most notable change was a reduction in essential FAA concentrations (principally in valine, leucine and isoleucine) in the white muscle following feeding. However, in the caeca total FAA, total essential FAA and a number of individual FAA were significantly elevated at 4, 9 and 15h following feeding. There were few significant correlations between dietary amino acid consumption and total tissue FAA and essential FAA concentration in the stomach, caecum and white muscle; correlations were stronger in the liver. In order to explain the relative constancy of total FAA concentrations in the tissues following food intake (which represents over 100% of the total FAA pool) a model is presented that quantifies the AA flux through the free pools and considers the role of protein turnover in regulating FAA pool size.     

Supplementation of potassium, magnesium and sodium chloride in practical diets for the Pacific white shrimp, Litopenaeus vannamei, reared in low salinity waters

The culture of Litopenaeus vannamei in inland low salinity waters is currently being practiced in various countries around the world. These environments are often deficient in key ions essential for normal physiological function, including potassium (K⁺) and magnesium (Mg²⁺). Farmers have sometimes been able to counteract ionic deficiencies in the water profile by adding mineral salts containing sources of K⁺ and Mg²⁺. The purpose of this study was to explore the possibility of correcting deficiencies of K⁺ and Mg²⁺ in the water profile with dietary supplementation of these minerals. Two separate 7‐week experiments were conducted in 4.0 g⁻¹ artificial low salinity water to evaluate the effects of mineral supplements (K⁺, Mg²⁺ and NaCl) to diets of L. vannamei reared in low salinity waters. In trial 1 seven diets were formulated (10 g NaCl kg⁻¹, 20 g NaCl kg⁻¹, 150 mg kg⁻¹ Mg²⁺, 300 mg kg⁻¹ Mg²⁺, 5 g K⁺ kg⁻¹, 10 g K⁺ kg⁻¹, and a basal diet to serve as a control). Minerals were added in the form of purified potassium chloride (KCl), magnesium chloride (MgCl₂·6H₂O) and NaCl. Trial 2 evaluated the use of a coating agent for the Mg²⁺ and NaCl treatments, while a K⁺ amino acid complex was utilized in the K⁺ treatments to reduce mineral leaching. Trial 2 was performed using similar treatment levels as trial 1. Shrimp survival and growth were assessed in both experiments. Results from trial 1 indicated no significant differences in survival, growth or percent weight gain. Results from trial 2 revealed no significant differences in survival and growth in the NaCl and Mg²⁺ treatments. However, significant differences in growth (P < 0.05) were observed when using the 10 g K⁺ kg⁻¹ treatment, suggesting that dietary supplementation of a K⁺ amino acid complex may help improve growth of the species in low salinity waters.     

Effects of steroid hormones on in vitro oocyte maturation in white sturgeon (Acipenser transmontanus)

The in vitro effects of several steroids on the maturation of intact white sturgeon (Acipenser transmontanus) ovarian follicles were investigated. At the highest concentration (1024 ng ml^–1 for the C21 steroids and 1139 ng ml^–1 for the C19 steroids), all of the C21 steroids tested, progesterone (P4), 17-hydroxyprogesterone (17OHP), 17,20-dihydroxy-4-pregnen-3-one (17,20-P), 17,(20,21-trihydroxy-4-pregnen-3-one 20-S), 11-deoxycortisol (S) and cortisol (F), as well as testosterone (T) induced germinal vesicle breakdown (GVBD) at 14 and 22 h. At 6 h, only P4 and 17,20-P induced maturation at the highest concentration (1024 ng ml^–1). At 14 and 22 h, 11-deoxycortisol was the most potent steroid inducer of GVBD followed by P4, 17OHP, 17,20-P, and 20-S. The steroid 11-hydroxytestosterone (11OHT) was completely ineffective at all concentrations and exposure times. The C21 steroids induced oocyte maturation at concentrations ranging from 4 to 1024 ng ml^–1, whereas T induced GVBD at 225 to 1139 ng ml^–1. Calculation of the mean effective concentration that induced 50% GVBD (EC50) from the 22 h incubations revealed the following order of potencies: S > P4 > 17OHP > 17,20-P > 20-S >> F > T. These bioassay results, together with previous findings on the endogenous production of steroids by ovarian follicles from gonadotropin-primed females, indicate that more than one steroid has a biological role in the resumption of meiosis in sturgeon oocytes and provides empirical evidence for P4, 17OHP, S, 20-S, and 17,20-P as maturation-inducing steroids in white sturgeon.     

Dietary protein level and natural food management in the culture of blue (Litopenaeus stylirostris) and white shrimp (Litopenaeus vannamei) in microcosms

The effect of dietary protein level and natural food management on the production parameters of blue and white shrimp, as well as on water quality, was evaluated in a microcosms system (plastic pools simulating aquaculture ponds). Two experimental trials were carried out in the facilities of DICTUS, University of Sonora, Northwest México. Treatment with low protein diet (LP) consisted of a low protein input (diet with 250 g kg^?1 crude protein) through the culture period; treatment with high protein diet (HP) consisted of a high protein input (diet with 400 g kg^?1 crude protein) through the trial, and finally treatment VP consisted of an adjustment of protein input (diets with 250, 350 or 400 g kg^?1 crude protein), depending on the abundance of biota (zooplankton and benthos) in the system. Each species responded differently to the treatments. For blue shrimp, low protein input resulted in the lowest final body weight (12.9 ± 0.6 g) and biomass (696.0 g pool^?1). Survival and feed conversion ratio were similar in the three treatments. For white shrimp, the best growth, biomass and food conversion ratio were obtained in the low protein input treatment. Water quality parameters such as nitrate, ammonia and organic matter during the two trials, were better for LP and VP treatments. White shrimp seems to have lower protein requirements than blue shrimp. For the blue shrimp culture, adjusting protein input according to natural food abundance (zooplankton and benthos) in the system, seems to be advantageous because of the possibility of getting a production similar to that obtained with a high protein input through the farming period, but at lower feed cost, and with a lower environmental impact. It is concluded that a high protein input through the whole farming period is not the best feeding strategy for any of the two species.