On the transferrin concentration in serum of sows and growing pigs and in sow colostrum

Immunologically pure transferrin was isolated from swine serum by means of ammoniumsulphate precipitation and ion-exchange chromatography. Rabbit anti-swine transferrin serum was prepared and used for immunological determinations of transferrin in serum and colostrum. The transferrin concentration in serum from piglets was 180 ± 56 mg/100 ml at birth and rather constant by the first days of life. The levels increase to 610 ± 78 mg/100 ml at 6 weeks after birth. The transferrin level of colostrum was 100 mg/100 ml and decreased rapidly. A negative correlation was established between the concentration of haemoglobin and transferrin. The importance of transferrin is discussed.     

Best among unequals? Effect of size grading and different social environments on the growth performance of juvenile Atlantic halibut

In order to study the effect of rearing juvenile halibut in different social environments, individually tagged juvenile halibut were size-graded into two size classes (Large, L, and Small, S) with ungraded fish as control. After ca 6 weeks, the two size-graded groups were again graded into two size classes creating four experimental groups: Large of the Large (LL), Small of the Large (SL), Large of the Small (LS), and Small of the Small (SS). Grading (overall mean of the four grading groups) improved growth rate by 10% compared with ungraded controls, but the effect was also significantly affected by social environments, because in the latter half of the experiment overall growth was improved by 11 and 12% in the two groups with larger size variation (i.e. SL and LS, respectively) compared with the two other groups (i.e. LL and SS). Significant size rank correlations were maintained during the experiment, these were higher in the ungraded (Control) group and the SS and LL groups than in the SL and LS groups. Further, the degree of mean rank position changes varied between the experimental groups and was higher in the SL (20.7) and LS (25.6) groups than in the Control (10.5), LL (15.1), and SS (15.4) groups. This could possibly indicate a stronger social hierarchy in the last three groups. Growth rate differences may be the product of different degrees of interactions among individuals, and based on the higher overall growth rates in the groups with larger size variation (i.e. SL, LS) it is concluded that juvenile halibut should not be too intensively size graded. Imsland and Jenssen have contributed equally.     

The relation between age at first maturity and growth in Atlantic halibut (Hippoglossus hippoglossus) reared at four different light regimes

The effect of extended photoperiods on growth and age at first maturity was investigated in 166 (79 females and 87 males) individually tagged Atlantic halibut. The halibut were reared at 11°C on four different light regimes from 10 February to 6 July 1996: simulated natural photoperiod, (LDN), continuous light (LD24:0), constant 8 h light and 16 h darkness (LD8:16) and LD8:16 switched to continuous light on 4 May 1996 (LD8:16–24:0). From 6 July 1996 to 9 February 1998 the LD24:0 and LD8:16–24:0 were reared together under continuous light and the LDN and LD8:16 together under natural photoperiod. Juveniles subjected to continuous light exhibited faster growth than those experiencing a natural photoperiod or a constant short day. Moreover, the results suggest an overall growth enhancing effect of continuous light in females, but not in males. No females matured during the trial, but the proportion of mature males differed between the photoperiod groups, with significantly fewer males maturing in groups reared at continuous light. Independent of photoperiod regime and maturation status, females were significantly bigger than males from 14 April 1997 onwards. Immature males were bigger than maturing males from 23 March 1996 onwards. As continuous light reduced maturation at age 2+ in males, this could be used to reduce precocious maturation in males.     

Feeding behaviour and growth of lumpfish (Cyclopterus lumpus L.) fed with feed blocks

The aim of this project was to investigate if lumpfish can be fed using specially designed feed blocks instead of regular fish feed pellets. Two studies were performed. In Part I different designs of feed blocks were introduced and fish observed with underwater cameras to record feeding behaviour. Results indicate that lumpfish require feed blocks with grooves in order to graze from them and that the acclimation period is relatively short (2–4 hr) before the fish will use them as a feed source. In the second part of the project two duplicate groups of lumpfish with an initial mean (±SD) weight of 125.4 ± 45.7 g were individually weighed and randomly distributed into six 3.5 m³ circular flow‐through tanks with 45 fish in each tank. Fish in three tanks were fed using feed blocks with grooves and fish in three tanks were fed using a regular commercially available lumpfish extruded feed. Both groups received a daily feeding rate of 2% body/weight. From day 14 onwards, fish fed with marine pelleted feed had a significantly higher mean weight compared to fish fed with feed blocks. Although not significant, the condition factor was higher in the feed block group during the study period. Results from this study show that lumpfish will readily graze from feed blocks if they are presented in a way that allows them to do. In addition, the acclimation period required before the fish will utilize them appears to be short thus potentially allowing for their use in commercial salmon cages.     

Clinical Trial: Marine Lipid Suppositories as Laxatives

Cod-liver oil and other marine products containing polyunsaturated fatty acids have anti-inflammatory, anti-bacterial and anti-viral effects and may be useful in the treatment of various inflammatory and infectious diseases. We developed suppositories and ointment with 30% free fatty acid (FFA) extract from omega-3 fish oil. Our purpose was to evaluate the safety of marine lipid suppositories and ointment in healthy volunteers and to explore the laxative effect of the suppositories. Thirty healthy volunteers were randomized either to a study group administrating 30% FFA suppositories and applying 30% FFA ointment to the perianal region twice per day for two weeks, or to a control group using placebo suppositories and ointment in a double blinded manner. Results: No serious toxic effects or irritation were observed. In the study group 93% felt the urge to defecate after administration of the suppositories as compared to 37% in the control group (P = 0.001). Subsequently 90% in the study group defecated, compared to 33% in the control group (P = 0.001). Conclusion: The marine lipid suppositories and ointment were well tolerated with no significant toxic side effects observed during the study period. The suppositories have a distinct laxative effect and we aim to explore this effect in further clinical trials.     

Consequences of specialized breeding in the Swedish Warmblood horse population

In many European warmblood studbooks, clear specialization toward either jumping or dressage horses is evident. The Swedish Warmblood (SWB) is also undergoing such specialization, creating a possible need for separate breeding programs and a discipline-specific Young Horse Test (YHT). This study investigated how far specialization of the SWB breed has proceeded and the potential consequences. Individuals in a population of 122,054 SWB horses born between 1980 and 2020 were categorized according to pedigree as jumping (J), dressage (D), allround (AR), or thoroughbred (Th). Data on 8,713 J horses and 6,477 D horses assessed for eight traits in YHT 1999–2020 were used to estimate genetic parameters within and between J and D horses and between different periods. Future scenarios in which young horses are assessed for either jumping or dressage traits at YHT were also analyzed. More than 80% of horses born in 1980–1985 were found to be AR horses, while 92% of horses born in 2016–2020 belonged to a specialized category. The average relationship within J or D category was found to increase during the past decade, whereas the relationship between these categories decreased. Heritability estimates for gait traits were 0.42–0.56 for D horses and 0.25–0.38 for J horses. For jumping traits, heritability estimates were 0.17–0.26 for J horses and 0.10–0.18 for D horses. Genetic correlations between corresponding traits assessed in J and D horses were within the range 0.48–0.81, with a tendency to be lower in the late study period. In the future scenarios, heritability and genetic variance both decreased for traits that were not assessed in all horses, indicating that estimation of breeding value and genetic progress for these traits could be affected by a specialized YHT. However, ranking of sires based on estimated breeding values (EBVs) and accuracy of EBVs was only slightly altered for discipline-specific traits. With continued specialization in SWB, specialization of the YHT should thus be considered.     

Genomic selection strategies to improve maternal traits in Norwegian White Sheep

This study tested and compared different implementation strategies for genomic selection for Norwegian White Sheep, aiming to increase genetic gain for maternal traits. These strategies were evaluated for their genetic gain ingrowth, carcass and maternal traits, total genetic gain, a weighted sum of the gain in each trait and rates of inbreeding through a full-scale stochastic simulation. Results showed genomic selection schemes to increase genetic gain for maternal traits but reduced genetic gain for other traits. This could also be obtained by selecting rams for artificial selection at a higher age. Implementation of genomic selection in the current breeding structure increased genetic gain for maternal traits up to 57%, outcompeted by reducing the generation interval for artificial insemination rams from current 3 to 2 years. Then, total genetic gain for maternal traits increased by 65%–77% and total genetic gain by18%–20%, but at increased rates of inbreeding.     

Role of dietary ascorbic acid in vitellogenesis in rainbow trout (Salmo gairdneri)

Adult rainbow trout which were fed a diet devoid of ascorbic acid for 21 months, including the stages of gonadal development, showed no macroscopic signs of avitaminosis C and no increased mortality compared to a control group of fish with dietary supplementation of this vitamin. Fish without dietary supplementation of ascorbic acid contained more lipid in the liver and less in the ovaries than the reference fish. The lipid metabolism of the maturing fish is thus affected when the dietary intake of ascorbic acid is very low or absent. Fish without dietary ascorbic acid became anaemic (reduced levels of haemoglobin and haematocrit) towards the end of the feeding period. The serum levels of oestradiol-17β and vitellogenin were also lower in these fish. Possible modes of action of ascorbic acid in maturing rainbow trout are discussed on the basis of the presented analytical data on ascorbic acid, gross composition, blood serum levels of oestradiol-17β, vitellogenin, total protein, albumin, cholesterol, calcium, phosphorus and haematological parameters.