Sow litter size is increased in the subsequent parity when lactating sows are fed diets containing n-3 fatty acids from fish oil.

Supplementing diets with n-3 fatty acids from fish oil has been shown to improve reproductive performance in dairy cattle and sheep, but there is little published literature on its effects in sows. The aim of this study was to evaluate the reproductive performance of sows fed fish oil as a source of n-3 PUFA prefarrowing and during lactation. From d 107.7 ± 0.1 of pregnancy, 328 sows ranging in parity from 0 to 7 (parity 1.95 ± 0.09, mean ± SE) were fed either a diet containing tallow (control) or an isocaloric diet containing 3 g of fish oil/kg of diet (n-3). Diets were formulated to contain the same amount of DE (13.9 MJ/kg), crude fat (54 g/kg), and CP (174 g/kg). Sows were fed their treatment diet at 3 kg daily for 8 d before farrowing and continued on treatment diets ad libitum until weaning at 18.7 ± 0.1 d of lactation. After weaning, all sows were fed a gestation diet without fish oil until their subsequent farrowing. There was no effect (P > 0.310) of feeding n-3 diets prefarrowing on piglet birth weight, preweaning growth rate, piglet weaning weight, or sow feed intake. However, n-3 sows had a larger subsequent litter size (10.7 ± 0.3 vs. 9.7 ± 0.3 total born; 10.2 ± 0.3 vs. 9.3 ± 0.3 born live; P < 0.05). In conclusion, this is the first study to demonstrate that feeding sows a diet containing n-3 PUFA from fish oil fed before farrowing and during lactation increased litter size in the subsequent parity independent of energy intake.

A single nucleotide polymorphism in suppressor of cytokine signalling-2 is associated with growth and feed conversion efficiency in pigs.

Feed efficiency and growth are the most important traits in pig production, and very few genetic markers have been reported to be associated with feed efficiency. The suppressor of cytokine signalling-2 (encoded by SOCS2) is the main negative regulator of somatic growth, and the knockout of SOCS2 and naturally mutant mice have high-growth phenotypes. Porcine SOCS2 was selected as a primary positional candidate for feed efficiency, because it is located on chromosome 5q, in the vicinity of a Quantitative Trait Locus (QTL) region for food conversion ratio in pigs. Here, we report five single nucleotide polymorphisms identified by sequencing of the promoter region and exon 1. One PCR-RFLP assay was designed for genotyping the polymorphism c.1667A > G (GenBank Accession No AY312266). Association analyses were performed in an Australian mapping resource pedigree population (PRDC-US43) for food conversion ratio, backfat, IGF1 level and growth traits and showed significant effects on average daily gain on test (ADG2) (P < 0.01) and marginal association with food conversion ratio (FCR) (P < 0.08).

Sire breed comparisons for meat and eating quality traits in Australian pig populations.

Sire breed comparisons for carcase (n = 1169), meat and eating quality (n = 686) traits were obtained using data recorded on progeny of known pedigree sired by Duroc (DU), Large White (LW), Landrace (LR) and Duroc Synthetic (DS) boars from crossbred (LW/LR) sows. Animals were reared in eco-shelters in large single-sex contemporary groups and slaughtered on an age constant basis at 22 weeks of age. Compared to progeny from other sire groups, animals sired by purebred Duroc boars tended to have improved eating quality traits (higher intramuscular fat and lower shear force) at the expense of poorer carcase characteristics (higher subcutaneous and belly fat). Animals sired by DS boars tended to be heavier and leaner than those sired by LW, LR or DU boars; intramuscular fat but not belly fat was correspondingly lower, while tenderness was generally consistent with that of the DU progeny. Significant variability of sire progeny groups within sire breed suggests that sire breed selection, potentially used for improving traits such as meat quality in commercial progeny, will be less accurate in the absence of sire-specific information, which is typically poorly recorded in this class of traits.

Leptin expression in offspring is programmed by nutrition in pregnancy.

Birth weight is a determinant of blood leptin concentrations in adults. Since nutrition during pregnancy can affect birth weight, the hypothesis that feed intake during pregnancy alters leptin expression in progeny was examined. Leptin mRNA was measured in subcutaneous adipose tissue and leptin protein was measuredin blood plasma from 59 day old female pigs whose mothers were fed at the same restricted rate except that half were permitted to consume 35% more feed during the second quarter of pregnancy. Leptin mRNA abundance in adipose tissue (P=0.015) and plasma leptin concentration (P=0.01) were higher in progeny from mothers provided with more feed. Body weight at birth was negatively correlated with the abundance of leptin mRNA in subcutaneous fat at 59 days of age (P=0.01). This study shows for the first time that maternal nutrition during pregnancy programs postnatal leptin expression in offspring.

Quantitative genetics and evolution: Is our understanding of genetics sufficient to explain evolution?

SUMMARY: We have provided a bridge between geneticists, who tend to concentrate on genes and their frequencies, and other biologists, who are much more aware of how severely the environment constrains and limits life. This bridge is the recognition that a . fitness is a product of important component traits, b . these and most other traits consume environmental resources and these resources are additively related and can sum to no more than the total resources an animal can obtain from the environment, c . allele frequencies can alter only to the degree that the phenotypes that carry the alleles reproduce themselves successfully, i. e. are fit, d . fitness must rise, because it is never free from natural selection upwards, to the point where it can rise no further, because all environmental resources available to an animal are being used most efficiently, e . in this state of adaptation, fitness is completely limited by the environment and all other traits important to the animal are constrained to a greater or lesser degree at intermediate, "optimal" values, and f . traits or molecules unimportant to animals, so that they are completely neutral with respect to fitness, are free to drift genetically and hence gene substitutions can occur at rates related to their mutation rates. This bridge between genetics and other parts of biology shows that the various theories apparently causing concern for the modern synthetic theory of evolution are entirely compatible with it. Bursts of rapid evolutionary change between long periods of evolutionary stasis are the necessary consequences of strong natural selection acting on fitness, in ecosystems that are stable until external forces cause them to change. Neutral (random) evolution describes the fate of genetic material that is unimportant for organisms, i. e. material that is truly neutral with respect to fitness. ZUSAMMENFASSUNG: Quantitative Genetik und Evolution. Genügt unser genetisches Verständnis um Evolution zu erklären? Wir bauten eine Brücke zwischen Genetikern, die mit Genen und ihren Frequenzen arbeiten, und anderen Biologen, die wissen wie stark die Umwelt Lebewesen hemmend beeinflußt. Diese Brücke besteht aus den folgenden Erkenntnissen: a . Fitness ist ein Produkt der wichtigsten Komponenten. b . Diese und die meisten anderen Merkmale verbrauchen Nahrung. Die Nahrung, die ein Lebewesen nur aus der Umwelt erhalten kann, enthält die maximale Summe der metabolischen Ressourcen, die das Wesen dann in additiver Weise in einzelne Merkmale investiert. c . Allelfrequenzen können sich nur erhöhen, wenn der Phänotyp, der die Allele trägt, sich erfolgreich fortpflanzt. d . Weil Fitness immer unter natürlicher Selektion nach oben steht, muß der Fitnesswert steigen bis alle Umweltressourcen so effizient wie möglich genützt werden. e . In solchem Stadium der völligen Anpassung an die Umwelt, ist Fitness ganz durch die Umwelt limitiert und alle anderen wichtigen Merkmale in größerem oder kleinerem Maße in Optimalwerte gezwängt. f . Unwichtige Merkmale oder genetische Moleküle, die keine Wirkung im Lebewesen haben, so daß sie wirklich neutral sind gegenüber Fitness, dürfen ungehemmt driften und zeigen deshalb Substitutionsraten, die ihren Mutationsraten entsprechen. Diese Brücke zwischen Genetik und der übrigen Biologie zeigt, daß die Evolutionstheorien, die angeblich die moderne Evolutionssynthese stören, vollkommen mit ihr im Einklang sind. Sprungartige Evolution zwischen langen, stabilen Zeiträumen sind die Zwangsfolgen starker natürlicher Selektion auf Fitness in Ökosystemen, die sich nicht ändern bis ein Druck außerhalb des Systems das bewirkt. Neutrale Evolution beschreibt, was mit dem Material passiert, das unwichtig für Lebewesen ist.

Selection response for litter size at birth and litter weight at weaning in the first parity in mice.

Five 60-pair lines of mice were selected for seven generations for the following criteria: number born alive (LSO), random selection of litters (LC), number born alive divided by the weight of the dam at 9 weeks (LSO/DWT), total litter weight weaned divided by the weight of the dam at 9 weeks (LWT/DWT), and weight of litter weaned (LWT). All traits were measured in the first parity only and litters were not standardized. Realized heritabilities for LSO, LWT, LSO/DWT, and LWT/ DWT were 0.10± 0.06, 0.11±0.07, 0.22 ± 0.04, and 0.22 ± 0.08, respectively. Selection response for the two ratio lines was due to correlated responses in the respective numerators, LSO and LWT, as DWT did not decrease. In terms of improving LWT, selection for LWT/ DWT was three times as effective as selection for LSO/ DWT.