Effect of vitamin supplements on some aspects of performance, vitamin status, and semen quality in boars

The aim of the present study was to determine the effects of dietary supplements of vitamins on vitamin status, libido, and semen characteristics in young boars under normal and intensive semen collection. Sixty Landrace, Yorkshire, and Duroc boars were allocated randomly from 6 to 10 mo of age to one of the following diets: 1) basal diet (industry level) for minerals and vitamins (Control, n = 15); 2) basal diet supplemented with vitamin C (ASC, n = 15); 3) basal diet supplemented with fat-soluble vitamins (FSV, n = 15); and 4) basal diet supplemented with water-soluble vitamins (WSV, n = 15). After puberty (approximately 12 mo of age), semen was collected at a regular frequency (three times every 2 wk) for 5 wk. Thereafter, all boars were intensively collected (daily during 2 wk). A recovery period (semen collection three times every 2 wk) followed and lasted for 10 wk. Sperm quality (percentage of motile cells and percentage of morphologically normal cells) and quantity (sperm concentration, semen volume, and total sperm number) were recorded as well as direct and hormone related measurements of boar libido. Blood and seminal plasma samples were taken to monitor vitamin status. High concentrations of B6 (P < 0.05) and folic acid (P < 0.05) were observed in the blood plasma of WSV boars, whereas greater concentrations of vitamin E (P < 0.01) were obtained in FSV boars. In the seminal plasma, folic acid concentrations tended to be greater in WSV boars (P < 0.08). During the intensive collection period, there was a tendency (P < 0.06) for semen production to be greater in WSV boars, the effect being less pronounced (P < 0.10) in FSV boars. During the recovery period, the percentage of motile sperm cells was greater in WSV boars (P < 0.03) and, to a lesser extent, in FSV boars (P < 0.10) compared with Control boars. Sperm morphology and libido were not affected by treatments. These results indicate that the transfer of vitamins from blood to seminal plasma is limited and the dietary supplements of water-soluble and fat-soluble vitamins may increase semen production during intensive semen collection.     

Feeding larvae of winter flounder Pseudopleuronectes americanus (Walbaum) with live prey or microencapsulated diet: linear growth and protein, RNA and DNA content

A commercial microencapsulated diet was used as a total or partial replacement of live prey for feeding larvae of winter flounder Pseudopleuronectes americanus (Walbaum), a potential alternative finfish species for coldwater marine aquaculture. Growth performance (morphometric measurements and biochemical composition) and nutritional condition (RNA/DNA ratios) of larvae fed live prey (Brachionus plicatilis Müller), a microencapsulated diet or a mixed diet of live prey and microcapsules were compared. Newly hatched larvae were unable to digest microencapsulated diet; live prey at initial feeding was required for their survival and growth. Larvae offered a mixed diet showed slower growth than larvae fed exclusively with live prey. However, at the onset of stomach differentiation, RNA/DNA ratios (indicators of protein synthesis potential) of the larvae fed both diets became similar. We suggest that, at that stage (size 5.5–6.3 mm), enzymatic activity had developed enough to allow digestion of inert food. As the RNA/DNA ratio is a good indicator of nutritional condition, it appears to be an interesting tool for the assessment of diet adequacy in marine larval feeding technology.     

Examining the ecological paradox of the ‘mycorrhizal-metal-hyperaccumulators’

This analysis identifies and attempts to resolve the paradox of combining plant hyperaccumulators and arbuscular mycorrhizal fungi (AMF) for the purpose of post-industrial bioremediation due to the divergence of their respective ecological and evolutionary stress-tolerance behaviors. The identification of a ‘dilemma of resource allocation’ associated with plant resources consumed in intrinsic (e.g. metabolic) vs. extrinsic (e.g. symbiotic) stress-tolerance mechanisms could provide a suitable evolutionary reasoning for the apparent dichotomy existing between the hyperaccumulators and AMF–plant life-history strategies. Ultimately, it is considered that any efforts toward integrating such biotechnology innovations into bioremediation strategies (e.g. ‘mycorrhizal–metal-hyperaccumulators’) should first explicitly consider their inherent environmental and (or) evolutionary contexts to avoid misleading and possibly even unproductive outcomes prior to incorporating these attributes as potential technological solutions.     

Vitamin D3 fortification, quantification, and long-term stability in Cheddar and low-fat cheeses

Considering the widespread insufficiency of vitamin D, the fortification of additional foods with vitamin D is warranted. The objective of this research was to assess the feasibility of vitamin D3 fortification in natural hard cheeses. We examined the recovery, distribution, long-term retention, and heat stability of the vitamin in industrially made fortified Cheddar and low-fat cheeses. The results indicated that the vitamin D3 did not degrade during processing, over 1 year of ripening (3-8 degrees C), or after thermal treatment at 232 degrees C for 5 min. Vitamin D3 recovery in the fortified Cheddar and low-fat cheeses were, respectively, 91 and 55% of the vitamin D3 added to the milk used to make each cheese. The remaining vitamin D3 was entrained in the whey. The vitamin D3 was uniformly distributed throughout the blocks of cheese. The fortification process did not alter the yield, chemical composition, or flavor of the Cheddar cheese. We conclude that industrially manufactured Cheddar and low-fat cheeses are suitable for vitamin D3 fortification.     

Changes in lipid classes and trypsin activity during the early development of brook chair, Salvelinus fontinalis (Mitchill), fry

Fertilized eggs of brook charr, Salvelinus fontinalis (Mitchill), (Nashua X Baldwin domestic strains) held for 86 days under laboratory conditions from eggs to fry were split into three groups: FWF2, FWF3 and SWF2. Breeders originated from the same broodstock, but rearing procedures were different; FWF2 and FWF3 were always kept in fresh water, whereas SWF2 had spent the previous summer in sea water. The SWF2 and FWF2 females were sexually mature before the FWF3 females. The feeding experiment started 16 weeks after fertilization. Juveniles were fed with the same commercial pellets at three different levels, a complete ration (R1) and two restricted rations, 50% and 25% of R1. Eggs and fry were analysed for size, dry weight, total lipids, lipid classes (polar lipids, cholesterol and triglycerides), soluble proteins and trypsic activity. Although dry weight, mean length, soluble protein and trypsic activities increased with food availability lipid changes showed a permanent use of the endogenous reserve. No lipid synthesis was detected in any developmental stage, even though exogenous food sources were used. When the 25% restricted ration was given, fry mortality increased. Unexpectedly fry survival tended to increase in individuals from small eggs. The data from this study showed that reserve distribution and its use can improve the resistance of fry hatching from small eggs and prompt better survival despite changes in the nutritional environment. The two factors related to the breeders, summer environmental rearing conditions and sexual maturation time, had significant effects on the response of progeny to feeding conditions.     

Spatial distribution of Greenland halibut Reinhardtius hippoglossoides in relation to abundance and hypoxia in the estuary and Gulf of St. Lawrence

Annual bottom‐trawl surveys (1990–2010) were used to examine associations between environmental conditions, spatial distribution, and size‐specific abundance of Greenland halibut Reinhardtius hippoglossoides in the estuary and Gulf of St. Lawrence (EGSL), and to test the influence of hypoxic conditions on habitat selection. Size classes representing juvenile, immature and adult fish were used for the analyses. The highest concentrations of fish were found in the St. Lawrence estuary at both high and low levels of stock abundance. The areas occupied by 50, 75, and 95% of juvenile fish expanded with higher population abundance. However, contrary to our predictions, densities in marginal habitats did not increase at a higher rate than in optimal habitats. Fish longer than 32 cm were distributed over a broader area than juvenile fish. Their abundance explained a limited proportion of the variability in spatial distribution. The spatial dynamics of Greenland halibut in the EGSL is best described by a proportional density model where the rate of increase in local density is associated with population abundance. Habitats selected by Greenland halibut were characterized by low dissolved oxygen (DO) levels. The strong association between high fish densities and low DO concentrations indicates a high tolerance of Greenland halibut to hypoxia. It also indicates that negative effects, if present, could be compensated by other factors such as food availability and/or refuge from predation. The results of this study also clearly define the St. Lawrence estuary as the major nursery area for the EGSL population.     

Growth of early juvenile winter flounder (Pseudopleuronectes americanus Walbaum)

Metamorphosis is a critical developmental stage in marine fish species, but mortalities are also elevated at the settling phase. Our objective was to evaluate the effects of different rearing systems and larval diets on survival, general condition and pigmentation of newly settled winter flounder (Pseudopleuronectes americanus) juveniles. At settlement, winter flounder juveniles were reared in two different types of tanks (plankton kreisel and rectangular raceway). The early juveniles were followed for 1 month and their condition was evaluated using biochemical indices. Juveniles did not show signs of fin rot and pigmentation was well developed, but they had different RNA/DNA ratios. This study highlights the fact that rearing conditions at the onset of the juvenile stage may be critical for successful juvenile production.     

Comparison of stress responses in wild and captive winter flounder (Pseudopleuronectes americanus Walbaum) broodstock

Chronic stress is responsible for many problems occurring in fish holding facilities, such as increased susceptibility to disease, reduced growth rate and suppression of the immune response. The goal of this study was to verify if wild winter flounder (Pseudopleuronectes americanus Walbaum) suffer from chronic stress when kept several months in captivity. We hypothesized that winter flounder not subjected to chronic stress in captivity would have similar or higher condition indices and similar stress response compared to fish from the wild. Our results showed that the condition index of winter flounder kept in captivity was higher (1.50) than those from the wild (1.33) even after one year of captivity. The intensity of the acute stress response following short‐term exposure to air was similar between wild and captive fish (no significant interaction between the factors ‘stress’ and ‘origin of the fish’). Body water content (an indicator of energy reserves) was lower (76.1%) compared to wild fish (79.8%) after one year of captivity, suggesting that the winter fast had been less energetically demanding in captive fish. These results indicate that no chronic stress was present in captive fish. On the other hand, the mortality during captivity was around 30%, which is high for the aquaculture industry. Further work to address this problem is required.