Association of Ghrelin Gene Polymorphisms with Fattening Traits and Feed Intake in Pig: A Preliminary Study

Identification of Signatures of Positive Selection That Have Shaped the Genomic Landscape of South African Pig Populations

South Africa boasts a diverse range of pig populations, encompassing intensively raised commercial breeds, as well as indigenous and village pigs reared under low-input production systems. The aim of this study was to investigate how natural and artificial selection have shaped the genomic landscape of South African pig populations sampled from different genetic backgrounds and production systems. For this purpose, the integrated haplotype score (iHS), as well as cross population extended haplotype homozygosity (XP-EHH) and Lewontin and Krakauer's extension of the Fst statistic based on haplotype information (HapFLK) were utilised. Our results revealed several population-specific signatures of selection associated with the different production systems. The importance of natural selection in village populations was highlighted, as the majority of genomic regions under selection were identified in these populations. Regions under natural and artificial selection causing the distinct genetic footprints of these populations also allow for the identification of genes and pathways that may influence production and adaptation. In the context of intensively raised commercial pig breeds (Large White, Kolbroek, and Windsnyer), the identified regions included quantitative loci (QTLs) associated with economically important traits. For example, meat and carcass QTLs were prevalent in all the populations, showing the potential of village and indigenous populations' ability to be managed and improved for such traits. Results of this study therefore increase our understanding of the intricate interplay between selection pressures, genomic adaptations, and desirable traits within South African pig populations.

Fermented Diet Liquid Feeding Improves Growth Performance and Intestinal Function of Pigs

Simple Summary

The present study indicated that fermented liquid feeding improved the growth performance of pigs, which might be associated with gastrointestinal hormone and intestinal functions. These results provided a new perspective for improving the growth performance of pigs.

Abstract

Accumulating evidences demonstrate that fermented feed and liquid feeding exerted a great beneficial influence on growth performance and health in the pig industry. This experiment was conducted to evaluate the effects of fermented liquid feeding on the growth performance and intestinal function of pigs. Two hundred and eighty-eight 27-day-old weaned piglets (8.21 ± 0.27 kg) were randomly allocated to a control group (basal diet (CON)), an antibiotic group (basal diet supplemented with antibiotics (AB)) and a fermented liquid feeding group (basal diet with fermented liquid feeding (FLF)), with 6 replicates per treatment and 16 weaned piglets per replicate. The experiment lasted for 160 days. Fresh fecal samples were collected to evaluate the apparent total tract digestibility (ATTD) of nutrients from the last 4 days of each stage. The results are shown as follows: (1) Compared with the CON group, in the whole stage, the FLF diet significantly increased the final body weight (BW) and ADG of pigs (P < 0.05), and had a tendency to increase ADFI (P = 0.086), but had no effect on F/G. (2) The ATTD of dry matter (DM), crude protein (CP), ether extract (EE), crude ash (CA), crude fiber (CF), gross energy (GE), calcium (Ca) and total phosphorus (TP) in the FLF group was significantly elevated compared with those of the CON group at 8–20 kg stage (P < 0.05). Meanwhile, the ATTD of EE in the FLF group was significantly increased compared with that of the CON group at the 50–75 kg and 100–125 kg stages (P < 0.05), and the ATTD of Ca was higher than that of CON group at the 100–125 kg stage (P < 0.05). (3) Compared with that of the CON group, the level of serum leptin in the FLF group had a tendency to decrease (P = 0.054), the level of serum ghrelin in the FLF group was significantly elevated (P < 0.05) and the level of serum peptide YY in the FLF group was significantly decreased (P < 0.05). (4) The abundance of Lactobacillus in cecal and colonic digesta was observably enhanced in FLF group. Meanwhile, the abundance of Escherichia coli in cecal and colonic digesta were dramatically reduced in the FLF group compared with that in the CON and AB groups (P < 0.05). (5) The levels of acetic acid in colonic digesta were significantly increased in the FLF group (P < 0.05), and an increasing trend was observed in total VFA in colonic digesta compared with CON (P < 0.1). The levels of acetic acid in colonic digesta were significantly promoted in the FLF group compared with that of the AB group (P < 0.05). In conclusion, these results indicate that fermented liquid feeding improved the growth performance of pigs, which might be associated with gastrointestinal hormone and intestinal functions.

A Transcriptome Analysis Identifies Biological Pathways and Candidate Genes for Feed Efficiency in DLY Pigs

Feed cost accounts for approximately 65–75% of overall commercial pork production costs. Therefore, improving the feed efficiency of pig production is important. In this study, 12 individuals with either extremely high (HE) or low (LE) feed efficiency were selected from 225 Duroc × (Landrace × Yorkshire) (DLY) pigs. After the pigs were slaughtered, we collected small intestine mucosal tissue. Next, RNA sequencing (RNA-seq) analysis was used to reveal the presence and quantity of genes expressed between these extremely HE- and LE-groups. We found 433 significantly differentially expressed genes (DEGs) between the HE- and LE-groups. Of these, 389 and 44 DEGs were upregulated and downregulated in the HE-group, respectively. An enrichment analysis showed that the DEGs were mainly enriched in functions related to apical plasma membrane composition, transporter activity, transport process and hormone regulation of digestion and absorption. Protein network interaction and gene function analyses revealed that SLC2A2 was an important candidate gene for FE in pigs, which may give us a deeper understanding of the mechanism of feed efficiency. Furthermore, some significant DEGs identified in the current study could be incorporated into artificial selection programs for increased feeding efficiency in pigs.