Effect of Excessive or Restrictive Energy on Growth Performance, Meat Quality, and Intramuscular Fat Deposition in Finishing Ningxiang Pigs.

Jiayi Chen,Yurong Zhao,Yaodong Wang,Xue Lin,Fengming Chen,Jianhua He

doi:10.3390/ani11010027

Jiayi Chen, Yurong Zhao + Show 4 more

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https://doi.org/10.3390/ani11010027

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Abstract

Simple SummaryThe present study indicated that excessive energy enhanced fat deposition by upregulating expression of lipogenic genes in the longissimus thoracis of a Chinese fat-type pig. In addition, impairment in meat quality resulted in reduced meat tenderness and increased cross-sectional area of muscle fiber aroused by promoting glycolytic muscle fibers differentiation in muscles. These results provided a new perspective on the energy needs of Ningxiang pigs.This study investigated the effects of excessive or restrictive energy on growth performance, meat quality, intramuscular fat (IMF) deposition, and related gene expression in finishing Ningxiang pigs. A total of 36 Ningxiang pigs (43.26 ± 3.21 kg) were randomly assigned to three treatments (6 pens of 2 piglets per treatment) and fed by one of three dietary treatments until the pigs of each treatment weighed approximately 75 kg equally. The three treatments were control diet (digestible energy, DE:13.02 MJ/kg, CON), excessive energy diet (DE 15.22 MJ/kg, EE), and restrictive energy diet (DE 10.84 MJ/kg, RE). Results showed that EE improved average daily gain (ADG) and feed conversion ratio (FCR) (p < 0.01), while nothing significantly changed by RE except FCR increasing (p < 0.01). EE increased the content of IMF and triglycerides (TG) (p < 0.05), L*24h and b*45min (p < 0.01), while decreasing cooking loss and meat tenderness in longissimus thoracis (LT) (p < 0.05). b*24h was significantly increased with the increase of energy level (p < 0.01). Meanwhile, EE increased the cross-sectional area (CSA) of muscle fiber and the mRNA expression of myosin heavy chain (MyHC) IIb, acetyl CoA carboxylase (ACC), fatty acid synthase (FAS), and adipocyte fatty-acid binding protein (FABP4) (p < 0.05). In addition, throughout: A diet supplemented with excessive energy promoted IMF deposition by positively changing lipogenic potential while decreasing tenderness by increasing glycolytic muscle fibers, which together affected meat quality. In terms of growth performance and meat quality, the present study suggests that the low-energy diet is suitable for finishing Ningxiang pigs.

Highlights

In animals, adipogenesis firstly occurs in visceral fat, followed by subcutaneous and intermuscular, and is deposited in intramuscular fat last [1]
The present results, which showed a higher proportion of myosin heavy chain (MyHC) IIb, FABP4 abundance, and intramuscular fat (IMF) content in the EE group, were consistent with the fact that glycolytic muscle fibers were less oxidative and used fewer lipids as fuel substrate than other fiber types. These observations of the present study suggested that lipid anabolic pathways, intracellular trafficking of fatty acids supported by FABP, and myofiber energetic metabolism may contribute an explanation of IMF content increasing caused by excessive energy
RE is comparable to CON in terms of growth performance and meat quality of Ningxiang pigs, suggesting the acceptability to lower dietary energy in Ningxiang pigs

Summary

Introduction

Adipogenesis firstly occurs in visceral fat, followed by subcutaneous and intermuscular, and is deposited in intramuscular fat last [1]. IMF deposition is positively correlated with the percentage of oxidized muscle fibers but negatively correlated with glycolytic muscle fiber in the muscle [3]. It is generally believed that local pig breeds contain more oxidized muscle fibers, accounting for better meat quality but slow growth rate, while foreign pig breeds are known for their fast growth rate and high meat production but low meat quality due to containing more glycolytic fibers [4,5,6,7]. In addition to the genetic factor, the nutritional level affects the composition of muscle fiber types and IMF deposition. It has been reported that dramatic changes in fiber type composition (FTC) could be achieved by altering energy and nutrient balance during animal growth [8,9]. It is widely accepted that fat deposition is greater in muscles with increasing energy levels [10]

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