The intestinal mucosal development of piglets (Sus scrofa) during the weaning stage is important to their disease susceptibility and later growth. Quantitative real-time PCR (RT-qPCR) is commonly used to screen for differentially expressed genes and, for accurate results, proper reference housekeeping genes are essential. Here we assessed the mRNA expression of 18 well-known candidate reference genes at different parts of the gastrointestinal tract (GIT) of piglets during the weaning process by RT-qPCR assay. GeNorm analysis revealed that B2M/HMBS/HPRT1 were the three most stable reference genes and GAPDH was the least stable gene in the duodenum, jejunum, ileum, colon, and whole GIT. BestKeeper analysis found that B2M/HMBS/PGK11, HMBS/B2M/HPRT1, B2M/HMBS/HSPCB, B2M/HPRT1/HMBS, and B2M/HMBS/HPRT1 were the most stable genes in the duodenum, jejunum, ileum, colon, and whole GIT, respectively, whereas GAPDH, B-actin, and 18S rRNA were the least stable genes at different parts of the GIT. To confirm the crucial role of appropriate housekeeping genes in obtaining reliable results, we analyzed the expression of ALP using each of the 18 reference genes to normalize the RT-qPCR data. We found that the expression levels of ALP normalized using the most stable reference genes (B2M/HMBS/HPRT1) differed greatly from the expression levels obtained when the data were normalized using the least stable genes (GAPDH, B-actin, and 18S). We concluded that B2M/HMBS/HPRT1 were the optimal reference genes for gene expression analysis by RT-qPCR in the intestinal mucosal development stages of piglets at weaning. Our findings provide a set of porcine housekeeping reference genes for studies of mRNA expression in different parts of the pig intestine.

The objective of this experiment was to evaluate the growth performance, chemical composition, and functional amino acids (FAA) composition of two crossing systems between wild boars and different domesticated pig breeds. Forty castrated male pigs at 60 days of age from 3 breeds including Wild boar (W), Bamei (B) and Yorkshire (Y) and their crossing systems Wild boar × Bamei (W × B) and Wild boar × Yorkshire (W × Y) were assigned into five groups, respectively. After 100 days of feeding, the growth performance, chemical composition and amino acids (AA) in longissimus muscle were analysed. The ADG (P < .01) in W was lower than other breeds (B and Y) and their crossing systems (W × B and W × Y) (P < .01). The content of intramuscular fat (IMF) was decreased (P < .01) in W when compared with other breeds (B and Y) and their crossing systems (W × B and W × Y) (P < .01). In terms of the levels of FAA, leucine in W was lower than those of the other breeds (B and Y) or their crossing systems (W × B and W × Y) (P < .01), whereas the levels of proline, cysteine, glutamate, total FAA, total AA, and total FAA/total AA was the highest in the Wild boar (P < .01). Herein, cross breeding with domesticated pigs was shown to be an effective method to improve the growth performance of wild boars, and the extent of improvement was breed dependent. Compared with domesticated pigs and cross-bred pigs, wild boars showed lower growth rate, but lower IMF and better FAA composition in longissimus muscle.

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