Abstract

   The Yorkshire pigs, renowned for their remarkable growth rate, low feed
   conversion ratio (FCR), and high meat production, emerge as a novel
   preference for paternal breeding. In this study, we found that purebred
   paternal Yorkshire pigs (PY) surpass the purebred Duroc breed in terms
   of growth rate. Specifically, purebred PY attain a weight of 100 kg at
   an earlier age compared to purebred Duroc (Male, 145.07 vs. 162.91;
   Female, 145.91 vs. 167.57; p-value < 0.01). Furthermore, different
   hybrid combinations suggest that offspring involving purebred PY
   exhibit superior growth performance. Compared with purebred Duroc, the
   offspring of purebred PY have an earlier age in days (173.23 vs.
   183.54; p-value < 0.05) at the same slaughter weight. The changes of
   plasma metabolites of 60-day-old purebred boars in the two sire-breeds
   showed that 1335 metabolites in plasma were detected. Compared with
   Duroc, 28 metabolites were down-regulated and 49 metabolites were
   up-regulated in PY. Principal component analysis (PCA) discerned
   notable dissimilarities in plasma metabolites between the two
   sire-breeds of pigs. The levels of glycerol 3-phosphate choline,
   cytidine, guanine, and arachidonic acid increased significantly
   (p-value < 0.05), exerting an impact on their growth and development.
   According to our results, PY could be a new paternal option as a
   terminal sire in three-way cross system.

   Keywords: Duroc, cross system, paternal Yorkshire pig, plasma
   metabolomics

1. Introduction

   Specialized sire and dam line pigs are cultivated in modern pig
   breeding systems, with sire lines bred for excellent growth performance
   and high lean meat percentage, and dam lines emphasizing reproductive
   performance and maternal behavior. China is the unparalleled global
   leader in swine breeding, pork production, and consumption, having a
   substantial influence on worldwide markets [[52]1,[53]2]. Duroc has
   emerged as the predominant option for specialized paternal pig breeding
   in China [[54]3], primarily due to its rapid growth rate, elevated
   slaughter rate, high lean meat percentage, and promising economic
   returns [[55]4]. Therefore, 70% or more of pork production in China
   comes from DLY pigs, which are produced by hybrid breeding Duroc with
   (Landrace × Yorkshire) pigs [[56]5]. Nevertheless, in recent years,
   some weaknesses for Duroc have been identified, i.e., it exhibits low
   heritability of feed efficiency, a limited number of progenies, and a
   tendency to lose weight under abnormal conditions [[57]6,[58]7].
   Accordingly, more and more commercial breeding companies hope to
   develop different paternal pig breeds. Compared with Duroc, Yorkshire
   pigs not only have a faster growth rate and higher lean meat rate, but
   also have their bodybuilding appearance, excellent meat production
   performance and good stress resistance [[59]8,[60]9]. Commercial
   breeding companies have successively cultivated new strains of paternal
   Yorkshire pigs according to market demand differences. For example,
   Topigs Norsvin (TN) in Dutch has used Large White pigs as terminal
   sires to develop the TN Tempo swine, renowned for their robust piglet
   vitality, sturdy limb muscles, remarkable fattening performance, and
   high feed conversion rate.

   The metabolome may be conceptualized as comprising four principal
   biochemical domains: protein metabolism, carbohydrate metabolism,
   nucleic acid metabolism, and fatty acid metabolism [[61]10]. A
   comprehensive examination of the pig metabolome yields profound
   insights into the intricate molecular underpinnings of physiological
   functionality, growth and development [[62]11], genetic improvement,
   feed nutrition [[63]12], meat quality [[64]13], reproductive function
   [[65]14,[66]15], stress response [[67]16], and even the identification
   of maladies [[68]17]. The focus is, on the one hand, to find reliable
   biomarkers of animal phenotypic characteristics [[69]18], and, on the
   other hand, to analyze the material basis behind the different
   phenotypes [[70]19]. Previous studies have confirmed plasma/serum
   metabolome, which more closely captures the host’s metabolism, can
   differentiate between two pig breeds [[71]20]. Similarly, Rohart et al.
   used plasma metabolite detection results from different breeds to show
   that amino acid metabolite indicators such as lactate, alanine,
   isoleucine, and valine are related to the lean meat rate of different
   breeds of pigs [[72]21]. The research on pigs has demonstrated the
   advantages of metabolomics, providing new materials for the screening
   and rapid and accurate identification of biomarkers related to economic
   traits in pigs, and providing important references for understanding