The present research aimed to study twelve reproductive indicators related to litter size and the farrowing interval for three maternal (Polish Large White, Polish Landrace, and Yorkshire) and three paternal (Duroc, Berkshire, Hampshire) breeds, raised on two farms in Poland and a farm in the United States. The study included 196 sows (45 Polish Large White, 37 Polish Landrace, 26 Berkshire, 33 Duroc, 40 Yorkshire, and 15 Hampshire), which altogether gave birth to 736 litters. The Kruskal-Wallis test was used to verify the influence of the breed on the reproductive traits, with a post-hoc procedure for pairwise comparisons implemented in the pgirmes of R. The adegenet, ade4, and factoextra packages of R were used to conduct multivariate analysis of the traits by means of principal component analysis. The breed significantly (p ≤ 0.05) influenced the following traits related to litter size: the total number of piglets born per litter, the number and percentage of piglets born alive per litter, the percentage of stillborn piglets per litter, the number and percentage of weaned piglets per litter; and those related to the farrowing interval: the lengths of gestation, lactation, the farrowing-to-conception interval, and the farrowing interval. The breed did not statistically significantly influence the number of stillborn piglets per litter and the length of the weaning-to-conception interval. Polish Landrace and Polish Large White sows had the highest numbers of born (for both, the mean of 14.0), born alive (12.9 and 12.7), and weaned piglets (11.5 and 10.5), which statistically significantly differed from these parameters in the other breeds. Polish Landrace sows significantly differed from all the other breeds in terms of the percentage of weaned piglets (84.1%), while Berkshire sows in terms of gestation length (118.4 days).

Associations between polymorphisms in the myostatin, αA-globin and lactate dehydrogenase B genes and racing performance in homing pigeons | Dybus A, Proskura WS, Pawlina E, Nowak B | Agricultural Journals

The mating system of small populations, isolated as a result of habitat fragmentation, is a key factor in their survival. As such populations are at risk of losing their genetic variation, reduction of their evolutionary potential is a distinct possibility. A flexible mating system may therefore provide a means of maintaining genetic variation. The mating system of the edible dormouse (Glis glis), a small arboreal rodent endangered by the fragmentation of its habitats, is not well understood. To date, only one study has provided evidence of multiple paternity in dormice. We present the results of a four‐year study of eight isolated dormouse populations. Using 138 individuals and 10 polymorphic autosomal microsatellite loci, we examined the prevalence of multiple paternity in these populations. In addition, we investigated the frequency of communal nesting and the genetic relationships between the females and juveniles occupying a single nest box. We found a high prevalence of multiple paternity (70% of the litters were multiple‐sired), a weak genetic relationship between the juveniles and the accompanying females (in 81% of cases the female residing with juveniles in a nest box was not their biological mother) and a 10.5% frequency of communal nesting in all nests. Given the low genetic variability of dormice, the multiple paternity and promiscuity observed in this species can help to maintain its genetic diversity.

Over the last few decades, there has been a constant increase in sow litter size, the consequences of which include parturition duration extension, an increase in the percentage of stillborn and hypoxic piglets, and increased variation in piglet birth weight, which reduces their vitality. As such, it seems clear that further increasing sow fertility will generate difficulties and costs in rearing numerous litters with low birth weights. Therefore, the current study aimed to analyze the genetic background of sow hyperprolifcacy using a genome-wide association study (GWAS). The research included 144 sows in the maternal component, divided into two equal groups. The first group (control) consisted of females giving birth to the optimal number of piglets in their third and fourth litters (14-16), while the second group (cases) included those with excessive litter size (>16). The analyzed sows were genotyped using Illumina's PorcineSNP60v2 BeadChip microarray, comprising 64,232 single nucleotide polymorphisms (SNPs). Statistical analysis using R included quality control of genotyping data and GWAS analysis based on five logistic regression models (dominant, codominant, overdominant, recessive, and log-additive) with a single SNP marker as the explanatory variable. On this basis, one SNP (SIRI0000069) was identified on chromosome seven within the EFCAB11 (EF-hand calcium binding domain 11) gene that had a statistically significant effect on sow hyperprolificacy. Additionally, ten SNPs (INRA0007631, ALGA0011600, ALGA0043433, ALGA0043428, M1GA0010535 ALGA00443338, ALGA0087116, MARC0056787, ALGA0112928, and ALGA0089047) had a relationship with the analyzed feature at a level close to significance, set at 1^-5. These SNPs appear important since they are located on chromosomes on which a large number of quantitative trait loci (QTLs) and SNPs associated with reproductive characteristics, including litter size, have been identified.

Since copy number variants (CNVs) have been recognized as an important source of genetic and transcriptomic variation, we aimed to characterize the impact of CNVs located within coding, intergenic, upstream, and downstream gene regions on the expression of transcripts. Regions in which deletions occurred most often were introns, while duplications in coding regions. The transcript expression was lower for deleted coding (P = 0.008) and intronic regions (P = 1.355 × 10⁻¹⁰), but it was not changed in the case of upstream and downstream gene regions (P = 0.085). Moreover, the expression was decreased if duplication occurred in the coding region (P = 8.318 × 10⁻⁵). Furthermore, a negative correlation (r = − 0.27) between transcript length and its expression was observed. The correlation between the percent of deleted/duplicated transcript and transcript expression level was not significant for all concerned genomic regions in five out of six animals. The exceptions were deletions in coding regions (P = 0.004) and duplications in introns (P = 0.01) in one individual. CNVs in coding (deletions, duplications) and intronic (deletions) regions are important modulators of transcripts by reducing their expression level. We hypothesize that deletions imply severe consequences by interrupting genes. The negative correlation between the size of the transcript and its expression level found in this study is consistent with the hypothesis that selection favours shorter introns and a moderate number of exons in highly expressed genes. This may explain the transcript expression reduction by duplications. We did not find the correlation between the size of deletions/duplications and transcript expression level suggesting that expression is modulated by CNVs regardless of their size.

Phenotypic correlations between reproductive characteristics related to litter and reproductive cycle length in sows | Błażej Nowak, Anna Mucha, Wojciech Kruszyński, Magdalena Moska | Agricultural Journals