Effects of feeding and rearing systems on growth, carcass composition and meat quality in pigs

Abstract

Animal growth performance and quality of pork depend on the interactive effects of pig genotype, rearing conditions, pre-slaughter handling, and carcass and meat processing. This paper focuses on the effects of feeding and rearing systems (feeding level and diet composition, housing, production system, etc.) on growth performance, carcass composition, and eating and technological qualities of pork. The feeding level and protein : energy ratio can be used to manipulate growth rate or composition of weight gain. Restricted feed allowance strongly reduces growth rate and carcass fatness and also intramuscular fat (IMF) level, resulting in decreased meat tenderness or juiciness. Expression of compensatory growth due to restricted followed by ad libitum feeding modifies the composition of weight gain at both carcass and muscle levels, and may improve meat tenderness due to higher in vivo protein turnover. Decreasing the protein : energy ratio of the diet actually increases IMF and improves eating quality, but gives fatter carcasses. In contrast, a progressive reduction in the protein : energy ratio leads to similar carcass composition at slaughter but with higher IMF. Technological meat traits (pH1, pHu, colour, drip loss) are generally not affected by the level or protein : energy in feed. Modification of fatty acid composition and antioxidant level in meat can be obtained through diet supplementations (e.g. vegetable sources with high n-3 fatty acids), thereby improving the nutritional quality of pork. Influences of pig rearing system on animal performance, carcass and meat traits result from interactive effects of housing (floor type, space allowance, ambient temperature, physical activity), feeding level and genotype in specific production systems. Indoor enrichment (more space, straw bedding) generally increases growth rate and carcass fatness, and may improve meat juiciness or flavour through higher IMF. Outdoor rearing and organic production system have various effects on growth rate and carcass fatness, depending on climatic conditions and feed allowance. Influence on meat quality is also controversial: higher drip and lower pHu and tenderness have been reported, whereas some studies show improved meat juiciness with outdoor rearing. Discrepancies are likely due to differences between studies in rearing conditions and physiological responses of pigs to pre-slaughter handling. Specific production systems of the Mediterranean area based on local breeds (low growth rate, high adiposity) and freerange finishing (pasture, forests), which allows pig to express their genetic potential for IMF deposition, clearly demonstrate the positive effects of genotype 3 rearing system interactions on the quality of pork and pork products.

Influence of production system in local and conventional pig breeds on stress indicators at slaughter, muscle and meat traits and pork eating quality

“…The higher IMF proportion of the B pigs (3.93% v. 2.23% for B and LW, P < 0.001) was in accordance with their higher body fatness (Lebret et al, 2014). It is also in agreement with the results reported for IMF proportion (Labroue et al, 2000) or marbling density (Alfonso et al, 2005) in this breed, and confirms the great potential of local pig breeds for IMF deposition (Lebret, 2008;Pugliese and Sirtori, 2012). In agreement with the present results, lower LM collagen concentrations and higher proportion of non-reducible, thermo-resistant collagen cross-links were found in local Casertana compared with LW pigs at 330 days of age (Maiorano et al, 2013).…”

“…Other studies showed higher IMF in pigs reared in 'enriched' systems (higher indoor space allowance, straw bedding and/or outdoor access) systems compared with Breed, production system and meat quality in pigs conventional ones, but this was generally associated with fatter carcasses (Lebret, 2008). In contrast, some studies report no effect or decreased IMF and fatness in alternative systems, highlighting the role of nutritional factors on these traits that might overrule the housing effect (Millet et al, 2005 for review).…”

“…In contrast with the present data, a slight increase in pork juiciness was found in synthetic line or Duroc cross-breeds produced in the A system (Lebret et al, 2006 and, although the other sensory traits were not modified. Overall, influence of 'enriched' systems on pork sensory quality is often of low magnitude and, when significant, is usually due to the influence of feeding strategy and the level of physical activity, to a lesser extent, on muscle composition and metabolism (Millet et al, 2005;Lebret, 2008). Impacts of extensive production system on meat sensory quality are even more complex and contrasted between studies, as they result from direct and interactive effects of animal environmental conditions, nutritional strategy, response to pre-slaughter handling, etc., on muscle growth, composition and properties.…”

“…Therefore, an experiment was designed to determine the genetic and environmental effects on pork quality, using two contrasted pig breeds, the conventional Large White and the French local Basque exhibiting high eating quality (Labroue et al, 2000). These pigs were reared in different production systems, which influenced meat quality (Lebret, 2008 for review; Lebret et al, 2011). Pigs from both the breeds were reared in a conventional and in an alternative (indoor bedding and free outdoor access) system.…”

Effects of sex and dietary lysine on performances and serum and meat traits in finisher pigs

“…However, the responses found in the literature are controversial. Some authors have reported that protein restriction increases backfat thickness, being lower the effect on muscle lipid deposition (Lebret, 2008;Rodríguez-Sanchez et al, 2011) but others concluded that the influence can be higher on IMF proportion (Wood et al, 2008;Daza et al, 2010). Also, Madeira et al (2013) tested restricted Lys diets against a control in a fatty genotype (Alentejano) and in commercial crossbred pigs (Landrace × Pietrain) finding no effect on backfat depth but with an increase of IMF recorded only in the commercial pigs.…”