Growth rate of growing pigs is weakly correlated genetically with litter size,while the amount of genetic variation for growth rate changes with litter size

Abstract

We reasoned that if we assessed pigs for litter size and growth rate during the grow-out stage of production (25–100 kg body weight) we would find: 1) an unfavourable genetic correlation between litter size and growth rate; and 2) that the amount of additive genetic variation expressed for growth rate varies with litter size. We tested these premises by assessing 2212 litters from the Yorkshire breed for litter size, while 3038 growing pigs from 550 of these litters were assessed for growth rate during the grow-out stage of production. Genetic correlations were estimated using the additive genetic (co)variances obtained from a bivariate linear animal model fitted to litter size and growth rate. The amount of additive genetic variation expressed for growth rate as a function of litter size was estimated by fitting a univariate linear animal model with random regression on litter size. Our findings did not support the first of our premises as we found that the genetic correlation between litter size and growth rate was favourable (0.28±0.27), albeit not significantly different from zero. However, we were able to support our second premise as we found that the relationship between amount of additive genetic variation for growth rate and litter size was quadratic; the amount of additive genetic variation was highest in small and large litters (h²=0.60 and 0.65), and lowest in intermediate litter sizes (h²=0.29). These findings indicate that: 1) breeding for litter size would not reduce the growth rate of growing pigs; and 2) the amount of genetic variation for growth rate changes with litter size.     

The Norwegian minke whale DNA register: a data base monitoring commercial harvest and trade of whale products

The application of genetics for the management of natural resources is expanding, and within this field, DNA registers will play an increasing role. The Norwegian minke whale DNA register, established in 1996, was designed primarily as a control system to detect any attempts at illegal trade of products derived from other stocks of minke whale, or other whale species, under cover of the legal Norwegian harvest originating from the Northeast Atlantic. The register contains genetic data for 7644 of 7751 whales landed in the period 1997–2010. Profiles are established from sequencing part of the mtDNA control region, analysis of 10 STRs and a sex‐determining marker. Probabilities of genotypes matching between two randomly selected whales are 6.0^?04 and 3.0^?08 for five and eight of the STR loci, respectively. This permits verification of traded whale products via match to the register. The register has also been used in a number of ad hoc scientific studies resulting through the accumulation of genetic, demographic and biological data. Here, we review the register’s logistics, specifications and evaluate the potential to apply similar registers to control the exploitation of other marine species.     

Different long-term and short-term responses of land snails to clear-cutting of boreal stream-side forests

Effects of clear-cutting on biodiversity have mainly been studied in the short-term, although knowledge of longer term effects are often more important for managers of forest biodiversity. We assessed relatively long-term effects of clear-cutting on litter dwelling land snails, a group with slow active dispersal and considered to be intolerant to microclimate changes. In a pair wise design we compared snail abundance, species density, and species composition between 13 old seminatural stream-side stands and 13 matched young stands developed 40-60 years after clear-cutting. Using a standardized semi-quantitative method, we identified all snail specimens in a 1.5 l subsample of a pooled litter sample collected from small patches within a 20 × 5 m plot in each stream-side stand. From the young stands a mean of 135 shells and 9.5 species was extracted which was significantly higher than the 58.1 shells and 6.9 species found in old forests. Only two of the 16 species encountered showed a stronger affinity to old than to young forests. In short-term studies of boreal stream-side forests land snail abundance is reduced by clear-cutting. Our results indicate that this decline is transient for most species and within a few decades replaced by an increase. We suggest that local survival in moist stream-side refugia makes the land snails able to benefit from the higher pH and more abundant non-conifer litter in young than in old boreal forests. Our results highlight the importance of longer term studies as a basis for management guidelines for biodiversity conservation.     

Precipitating antibodies in experimental visna and natural progressive pneumonia of sheep

Serological responses of Icelandic sheep experimentally infected with visna virus (vv) were contrasted with responses in American Targhee sheep naturally infected with progressive pneumonia virus (PPV). Precipitating antibodies assayed by immunodiffusion were compared with the neutralising and complementing fixing antibody response. In experimental infections with vv, complement fixing and neutralising antibodies appeared early after infection and rose to high levels in all sheep, while precipitating antibodies were detected only at minimal titre. In natural infections with PPV, immune responses were less consistent and precipitating antibodies were detected more frequently than complement fixing or neutralising antibodies against PPV. These results may suggest important biological differences between the lytic fibroblast-tropic virus strains used for experimental infection of Icelandic sheep and the nonlytic macrophage-tropic strains of PPV circulating in nature. Lytic strains evoke a brisk response against the viral glycoprotein with high titre neutralising antibody while nonlytic strains induce a less consistent response to the glycoprotein.     

Influence of catchment characteristics,forestry activities and deposition on nitrogen export from small forested catchments

The ability to predict nitrogen export from forested catchments is essential in order to evaluate the effects of anthropogenic activities on the trophic status of lakes and sea areas, and to extrapolate the results to catchments from which no measurements are available. Data from 20 forested catchments (0.3–42 km²) in Finland and Sweden during the 10-year period 1979–88 were used to develop empirical multivariate regression models of average NO₃-N, NH₄-N and organic N export fluxes as a function of geomorphological, meteorological, hydrological, deposition and forest management variables. A combination of high inorganic N deposition or air temperature and a low extent of organic soils was related to (R² = 0.64) high losses of NO₃-N. A strong correlation between N deposition and air temperature makes it difficult to distinguish the effects of one variable from the other. Retention of deposited nitrogen is still high in most of the catchments. High losses of NH₄-N had the strongest correlation with forestry activities and stream density. A combination of drainage percentage and temperature was related to (R² = 0.53) losses of NH₄-N. The most important factors explaining spatial variability of organic N losses were clearly forestry activities. A combination of high percentage of drainage and clear-cutting was related to (R² = 0.81) high organic N losses. However, within the catchments, large-scale forest management practices were needed before any clear effect on spatial variability was detected. All the equations obtained were influenced by the choice of a limited number of catchments. No causal relationships between losses and the explaining variables can be inferred from this type of study.     

BMAA Inhibits Nitrogen Fixation in the Cyanobacterium Nostoc sp. PCC 7120

Cyanobacteria produce a range of secondary metabolites, one being the neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA), proposed to be a causative agent of human neurodegeneration. As for most cyanotoxins, the function of BMAA in cyanobacteria is unknown. Here, we examined the effects of BMAA on the physiology of the filamentous nitrogen-fixing cyanobacterium Nostoc sp. PCC 7120. Our data show that exogenously applied BMAA rapidly inhibits nitrogenase activity (acetylene reduction assay), even at micromolar concentrations, and that the inhibition was considerably more severe than that induced by combined nitrogen sources and most other amino acids. BMAA also caused growth arrest and massive cellular glycogen accumulation, as observed by electron microscopy. With nitrogen fixation being a process highly sensitive to oxygen species we propose that the BMAA effects found here may be related to the production of reactive oxygen species, as reported for other organisms.     

Effect of Feeding Environment on Performance,Injuries, Plasma Cortisol and Behaviour in Growing-finishing Pigs: Studies on Individual Pigs Housed in Groups

The effect of feeding environment on individual pigs (small, medium and large barrows) housed in groups of 16 pigs was studied. The experiment comprised the following four treatments: trough feeding, four dry feeders, one dry feeder and one wet/dry feeder per 16 pigs, respectively. Performance, skin injuries, plasma cortisol, agonistic behaviour, ingestive behaviour and activity were studied. The effect of competition for feed was most clearly evident for the small pigs. The small animals in the one dry feeder treatment were forced to eat more during the night, had more forced withdrawals from the feeder, and tended to have more scratches and skin injuries than did the small animals in the four dry feeder treatment. It was concluded that this competition led to impaired well-being in the smallest pigs. No significant differences were detected in plasma cortisol levels, when comparing the different feeding systems within each pig size category. Trough feeding greatly affected pig feed intake pattern: during the growing period when pigs had ad libitum access to feed, the pigs fed in a trough ate mostly at feeding times, while the pigs in the four dry feeder treatment ate at times spread out over the entire 24 h period. It was concluded that there was a confounding effect between pig size category (small or large) and feeding system with regard to ingestive behaviour and aggressive interactions at feeding.     

Human and ovine lentiviral infections compared

Maedi-visna virus (MVV) of sheep was the first lentivirus to be isolated. The genomic organization of MVV is very similar to that of human immunodeficiency virus (HIV) with several genes regulating the expression of the viral genome. Viral replication is severely restricted in the host and some cells apparently contain the genetic information in a DNA provirus form with little or no expression of viral antigens. This seems to be a major factor in causing the “slowness” of lentiviral infections and the persistence of the virus in the host since the immune system may not recognize the provirus-containing cells. The target cells for HIV and MVV are similar although T4 lymphocytes are not specifically destroyed in maedi-visna. There are also certain similarities in the pathological changes in both diseases, both in the central nervous system, the lungs and the lymphatic system. Although the severe final immunodeficiency state characteristic of AIDS has not been observed in maedi-visna, the basic biological features of the MVV and its interaction with host cells are so similar to HIV infection, that we consider ovine maedi-visna useful animal model for the human lentivirus infections.     

Composition and oxidative stability of crude oil extracts of corn germ and distillers grains

The fatty acid composition, Acid Value, and the content and composition of tocopherols, tocotrienols, carotenoids, phytosterols, and steryl ferulates were determined in corn germ oil and four post-fermentation corn oils from the ethanol dry grind process. The oxidative stability index at 110 °C was determined for the five oils, and four oils were compared for their stability during storage at 40 °C as determined by peroxide value and hexanal content. The fatty acid composition of all five oils was typical for corn oil. The Acid Value (and percentage of free fatty acids) was highest (28.3 mg KOH/g oil) in corn oil extracted centrifugally from a conventional dry grind ethanol processing facility and for oil extracted, using hexane, from distillers dried grains with solubles (DDGS) from a raw starch ethanol processing facility (20.8 mg KOH/g oil). Acid Value was lowest in two oils extracted centrifugally from thin stillage in a raw starch ethanol facility (5.7 and 6.9 mg KOH/g oil). Tocopherols were highest in corn germ oil (∼1400 μg/g), but tocotrienols, phytosterols, steryl ferulates, and carotenoids were higher in all of the post-fermentation corn oils. Hexane extracted oil from DDGS was the most oxidatively stable as evaluated by OSI and storage test at 40 °C, followed by centrifugally extracted thin stillage oil from the raw starch ethanol process, and centrifugally extracted thin stillage oil from the conventional dry grind ethanol process. Corn germ oil was the least oxidatively stable. When stored at room temperature, the peroxide value of centrifugally extracted thin stillage oil from the raw starch ethanol process did not significantly increase until after six weeks of storage, and was less than 2.0 mequiv. peroxide/kg oil after three months of storage. These results indicate that post-fermentation corn oils have higher content of valuable functional lipids than corn germ oil. Some of these functional lipids have antioxidant activity which increases the oxidative stability of the post-fermentation oils.     

Revisiting redox-active antioxidant defenses in response to hypoxic challenge in both hypoxia-tolerant and hypoxia-sensitive fish species

It is not known whether changes in antioxidant levels always occur in fish in response to the oxidative stress that usually accompanies a hypoxic challenge. The studies of antioxidant responses to hypoxia in fish have mostly focused on very anoxia-tolerant species and indicate that there is an enhancement of antioxidant defenses. Here we present new data on redox-active antioxidants from three species, which range in their tolerance to hypoxia: the epaulette shark, threespine stickleback, and rainbow trout, together with a compilation of results from other studies that have measured oxidative stress parameters in hypoxia-exposed fish. The results suggest that in general, fish do not show an increase in redox-active antioxidant defense in response to oxidative stress associated with hypoxia. Rather, the changes in antioxidant defenses during hypoxia are very much species- and tissue-specific and are not linked to the level of hypoxia tolerance of the fish species.