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Dietary Effects on Sperm Quality of Litopenaeus vannamei Broodstock   总被引:1,自引:0,他引:1  
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.  相似文献   
3.
Investigation of historic population processes using molecular data has been facilitated by the use of approximate Bayesian computation (ABC), which enables the consideration of multiple alternative demographic scenarios. The Lincoln Red cattle breed provides a relatively simple example of two well‐documented admixture events. Using molecular data for this breed, we found that structure did not resolve very low (<5% levels) of introgression, possibly due to sampling limitations. We evaluated the performance of two ABC approaches (2BAD and DIYABC) against those of two earlier methodologies, ADMIX and LEADMIX, by comparing their interpretations with the conclusions drawn from herdbook analysis. The ABC methods gave credible values for the proportions of the Lincoln Red genotype that are attributable to Aberdeen Angus and Limousin, although estimates of effective population size and event timing were not realistic. We suggest ABC methods are a valuable supplement to pedigree‐based studies but that the accuracy of admixture determination is likely to diminish with increasing complexity of the admixture scenario.  相似文献   
4.
Practical Molt Staging of Penaeus setiferus and Penaeus stylirostris   总被引:1,自引:0,他引:1  
Molt staging has many applications in penaeid aquaculture as a routine procedure. Using criteria developed for various crustaceans, a method of rapid molt staging was applied to Penaeus stylirostris and Penaeus setiferus adults. The most useful characters were the degree of epidermal retraction from the setal bases and epidermal retraction from the cuticle coupled with the development of new setae. The duration of the molt cycle of P. stylirostris was 11.5 ± 1.0 days ( N = 5) at 27–29 C. The early postmolt, late postmolt, intermolt, early premolt and late premolt stages were readily determined. For P. stylirostris , the duration of postmolt was 27% of the cycle; intermolt, 17%; and premolt, 56%. The length of the molt cycle of P. setiferus at 27–29 C was 13.6 ± 1.0 days ( N = 21) with postmolt occupying 22% of the cycle; intermolt, 19%; and premolt, 59%. Unilaterally eyestalk enucleated P. setiferus had a significantly shorter molt cycle than intact P. setiferus (11.7 ± 1.21 days vs. 13.6 ± 1.02 days, P < 0.05). There were no differences in molt cycle duration between the sexes, whether enucleated or intact ( P > 0.05). A series of illustrations identifies the key characteristics for determining stage of molt in these penaeids.  相似文献   
5.
The following acanthocolpid species are reported from New Caledonia. Acaenodera nautili sp. n. from Conger cinereus Rüppel differs from other Acaenodera species in details of the body-spination, the sucker-ratio and the bipartite seminal vesicle; Stephanostomum murielae sp. n. from Carangoides hedlandensis (Whitley) differs from most species of Stephanostomum in the average of 36 circum-oral spines, the circum-oral spine rows with a ventral hiatus and the anterior extent of the vitellarium being > 10% of the hindbody length from ventral sucker. The species is distinguished from the three other species with these characters in a detailed review. The other species reported are: Stephanostomum aaravi Bray et Cribb, 2003 from Lethrinus miniatus and L. rubrioperculatus; Stephanostomum ditrematis (Yamaguti, 1939) from Gnathanodon speciosus; Stephanostomum japonocasum Durio et Manter, 1969 from Cephalopholis urodeta, Epinephelus areolatus, E. chlorostigma, E. maculatus, E. retouti, Lethrinus miniatus and Variola louti; Stephanostomum uku Yamaguti, 1970 and Pleorchis uku Yamaguti, 1970 from Aprion virescens.  相似文献   
6.
The relationship between the pulmonary toxicity of 3- methylindole (3MI, skatole) and the mixed-function oxidase (MFO) system was investigated. Nine goats assigned to three groups were given a jugular infusion of [14C]3MI (0.02 to 0.03 g of 3MI/kg of body weight containing 0.5 muCi/kg of body weight) for 1.5 hours to induce acute pulmonary edema. Two groups of three goats each were treated with phenobarbital (PB) or piperonyl butoxide (BT) prior to 3MI infusion to induce or to inhibit the MFO system. Three goats were used as 3MI controls. During a 72-hour test period, blood was collected for determination of plasma 3MI concentration and radioactivity. Urine was collected and was fractionated by column chromatography. The severity of pulmonary lesions was evaluated by gross and microscopic examination. Pretreatment with BT prevented the onset of acute pulmonary edema. Goats pretreated with PB had more severe lung lesions than did 3MI controls. Plasma of goats pretreated with BT had a longer half-life (2.1 hours) of radioactivity, whereas plasma of goats pretreated with PB had a shorter half-life (1.0 hour) when compared with plasma of 3MI control goats (1.5 hours) given the same dosage of [14C]3MI (P less than 0.025). The plasma half-life of 3MI was longer (P less than 0.025) in BT-pretreated goats (0.45 hour) than that in PB-pretreated goats (0.26 hour). At 72 hours, 70% to 98% of the infused radioactivity had been excreted in the urine. The pattern of urinary metabolites of 3MI was altered in BT-pretreated goats compared with patterns in control and PB-pretreated goats. Results indicate that the MFO system is one of the pathways involved in the metabolism of 3MI and that pulmonary toxicosis results from metabolism of 3MI by this enzyme system.  相似文献   
7.
Concurrent bacteriologic culture of feces and agar gel immunodiffusion (AGID) testing was performed on all cows and bred heifers over 14 months old in 10 dairy herds during a 32-month period to determine the effectiveness of the AGID test for the detection of subclinical paratuberculosis. Herds were sampled 5 times and, when possible, culled animals were tested again at slaughter. During 5 herd-wide samplings, Mycobacterium paratuberculosis was isolated from 139 fecal specimens obtained from 109 cattle. Results of the AGID test were simultaneously positive 40 of 139 times (28.8%). Thirty-six of the 109 cattle (33.0%) determined to be infected had a positive AGID test result at some point during the 5 herd-wide samplings. When results of tests performed at time of slaughter were included, 117 cattle were identified as infected by culture methods; 55 of these (47.0%) were AGID test-positive at some point during the study. The upper limit of the maximal false-positive rate for the AGID test was 2.1%. On the basis of colony counts from cultures, subclinically infected cows shedding higher numbers of M paratuberculosis in their feces were more likely to have positive AGID test results (P less than 0.0001). In known infected cattle, neither the culture nor AGID test results were consistently positive on repeated testing. Of 48 official calfhood paratuberculosis vaccinates tested as adults, 3 had positive AGID test results and in 1 of these, M paratuberculosis was also isolated from the feces, indicating that the rate of false-positive AGID test results in calfhood vaccinates is low.  相似文献   
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9.
Oxidation during sampling procedures significantly decreases the inorganic phosphate concentrations of interstitial water rich in iron (II). All sampling and analytical procedures must be carried out in an inert atmosphere. Orthophosphate in the interstitial water of Cheaspeake Bay sediments, in equilibrium with vivianite, is a potential nutrient source for the overlying water.  相似文献   
10.
Bray JR 《Science (New York, N.Y.)》1977,197(4300):251-254
During the past 2 million years, major Northern Hemisphere eruptions occurred within 0.01 million years before 22 of 24 maximum-temperature dates which preceded the ten European glacial stages and 42 of 60 maximum-temperature dates which preceded the 22 cooling episodes. Massive eruptions were even more closely associated with the glacial stages and the cooling episodes. Within the errors of Pleistocene dating, major eruptions apparently occurred at the crucial moments to have triggered each of the ice ages.  相似文献   
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