Abstract
Simple SummaryFrom a production point of view, feed intake, growth and carcass quality are among the most important traits in pig breeding. Understanding the mechanisms and processes going on inside the animal’s body can help in the selection of herds and improvement in economic effectiveness. Previous research conducted on different species has showed that ghrelin (GHRL) is responsible for feed intake, efficiency of growth, etc. Thus, evaluation of the regulatory regions and coding sequence of the porcine GHRL gene may be useful as a molecular marker for selected fattening and feed efficiency traits. In this paper, a promising mutation at the locus g.4486C>T was found, which was associated with total feed intake. Numerous studies have been conducted to explain the biological functions and mechanism of ghrelin (GHRL) action in animals. However, the exact role of ghrelin in the regulation of growth and development in pigs is still unclear. The ghrelin gene is considered to be a good candidate marker for the identification of economically important traits in pig production such as feed intake, growth or carcass quality. The objectives of the present study were to investigate the regulatory regions and coding sequence of the porcine GHRL gene and determine the effect of polymorphisms at the ghrelin gene locus on selected fattening traits. Data were obtained from 346 gilts (pure breeds: Landrace, 188; Duroc, 74; Pietrain, 84). The PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism) method was used to detect polymorphisms within GHRL. Three polymorphisms were found, one in the promoter region (c.-93A>G) and two in the 3’UTR sequence (g.4428T>C; g.4486C>T). A significant (p ≤ 0.01) additive effect on daily gain (negative) and age at slaughter (positive) was obtained at the locus c.-93A>G. However, the most promising mutation was at the locus g.4486C > T, which is associated with total feed intake. Overall, the described GHRL polymorphisms may be useful as molecular markers in pig selection but future studies are required.
Highlights
The central melanocortin system appears to be a fundamental neuronal pathway that integrates a wide range of signals involved in the regulation of energy homeostasis
Administration of ghrelin has an effect on the growth hormone secretion but data regarding the mechanisms and regulation of growth and development are still limited [29]
Researchers have detected polymorphisms in ghrelin genes which are associated with carcass and meat quality traits in pigs [12,30], growth and feeding traits in chickens [20], growth traits in goats [31], birth weight and body length in cattle [16], and milk fat and protein synthesis in water buffaloes (Bubalus bubalis) [32]
Summary
The central melanocortin system appears to be a fundamental neuronal pathway that integrates a wide range of signals involved in the regulation of energy homeostasis. In mammals, it is defined as a collection of central nervous system circuits that include arcuate nucleus neuropeptide Y and agouti gene-related protein (NPY/AgRP) neurons or arcuate nucleus proopiomelanocortin (POMC) neurons; Animals 2019, 9, 410; doi:10.3390/ani9070410 www.mdpi.com/journal/animals. As well as insulin, decreases the expression of mRNA for arcuate NPY and AgRP genes, while ghrelin promotes their transcription [4] Both NPY and AgRP are neuropeptides that are considered to increase food intake and body weight [5,6,7]. Ghrelin stimulates food intake according to its orexigenic effect by activation of NPY/AgRP neurons, and leptin, which demonstrates anorexigenic activity, inhibits it [8]
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