Variation of heart size and its correlation with growth performance and vascular space in domestic pigs

Abstract

Heart size of purebred boars (13 Landrace, 12 Yorkshire, and 14 Duroc) and crossbred (Landrace × Yorkshire × Duroc) boars (no. =18) and gilts (no. = 24) was studied. Purebred boars were raised from 30 kg for 110 days and slaughtered. Crossbred pigs of various body weights (30 to 110 kg) were selected and their plasma and blood volume were measured before sacrifice. The variation of heart size of pigs was studied and its correlation with growth performance or to vascular space was investigated. According to the principal component analysis heart size was best expressed by its weight, followed by the thickness of the anterior ventricle septum or the thickness of the left ventricle (LV) wall. The food/gain ratio of boars during testing period was significantly correlated with some size characteristics of their heart including weight, width, and LV thickness. The back fat thickness at 100 kg was significantly negatively correlated with heart weight, heart/body weight ratio, and LV thickness. Thus, selection for growth performance would result in a bigger heart in domestic pigs. In the crossbred study, an allometry fitting of H = 12·18B0·73 (r = 0·96) was obtained between heart weight (H, g) and body weight (B, kg). The fittings of heart weight to blood/plasma volume generated values of r of between 0·79 and 0·75 in allometry models or between 0·84 and 0·80 in linear models. Thus, vascular space is no better than fractional body weight as the basis to express relative heart weight in pigs. It is suggested that the normal exponent relating heart size to body weight in growing pig is effectively 0·75, similar to the exponent of metabolic size, 0·734 or 0·75. Therefore, the size of the heart of domestic pigs varies in size proportionally with the changes of metabolism seen in terms of growth or maybe even reproduction. The wild boar, the ancestor of domestic pigs, has a heart proportionately about 0·5 bigger than modern pigs when scaled according to M0·75. The attribution of metabolic difference to the bigger heart of wild boar is uncertain and needs further elucidation. The trend to bigger hearts in domestic pigs under current selection pressure for leanness should not necessarily be interpreted as returning to a natural form but may reflect a pathophysiological change.

Heart size and mean muscle fibre cross-sectional area related to birth weight in pigs

“…In this study, the heart size averaged 350 g and constituted 0.33% of body weight. This is in accordance with earlier reports in which the relative heart weight of slaughtered pigs has ranged from 0.34% to 0.41% of body weight (Cliplef andMcKay 1993, Yang andLin 1997). We found a positive correlation between the birth weight and the heart weight at slaughter.…”

“…The size of the heart in the domestic pig has increased with the selection for higher weight gain and leaner carcasses (Cliplef andMcKay 1993, Yang andLin 1997), but the heart size may not have been able to keep pace with the development of muscle growth (Yang andLin 1997, Petrási et al 2003). In this study, the heart size averaged 350 g and constituted 0.33% of body weight.…”

“…We also found a positive correlation between the heart weight and the weight of muscles at slaughter (r = 0.778, P < 0.001). Yang and Lin (1997) reported that the heart weight correlated negatively with backfat thickness. In the present study, the muscle weight at slaughter explained 61% of the variation in the heart weight.…”

A comparative study on the expression profile of MCTs and HSPs in Ghungroo and Large White Yorkshire breeds of pigs during different seasons

“…The important anatomical and physiological constraints of pigs are small heart size, lower plasma and blood volume to their body weight ratio (Yang and Lin 1997), poor blood circulation with sparse capillarization (Ruusunen and Puolanne 2004), and higher percentage of white (type IIB fibers or fast glycolytic) fibers (Ruusunen and Puolanne 2004). Due to the above properties, even moderate physical activity derives its energy by anaerobic metabolism (Essen-Gustavsson 1986) whose end product is lactic acid (Nelson and Cox 2005).…”

The effect of dietary protein supply on carcass composition, size of organs, muscle properties and meat quality of pigs

“…In addition to the high-protein diet, the selection for leaner carcasses and faster growth rate produces pigs with larger hearts (Cliplef and McKay, 1993;Yang and Lin, 1997), livers, and kidneys (Cliplef and McKay, 1993). According to Cliplef and McKay (1993), the heart weights in relation to live weights ranged from 0.34 to 0.36 in the control group, and from 0.38 to 0.41 in the group selected for leaner carcasses and faster growth at a live weight of 90 kg.…”