Meat Science And Muscle Biology Symposium: In utero nutrition related to fetal development, postnatal performance, and meat quality of pork1

Abstract

Intrauterine growth restriction (IUGR) occurs naturally in pigs and leads to low birth weight of piglets due to undernutrition caused by placental insufficiency. For 2 main reasons, low birth weight causes economic loss. First, low birth weight pigs have a greater mortality and increasing the litter size causes more low birth weight piglets within litters. Second, surviving low birth weight piglets have reduced performance (i.e., ADG, feed conversion rate, and percentage meat). To develop dietary strategies for preventing IUGR, knowledge of the biological basis of IUGR is required. Muscle fiber number, formed during myogenesis, is correlated positively with performance traits and has been shown in several studies to be reduced in low birth weight pigs. Postnatal muscle hypertrophy is due to satellite cell number per fiber at birth and their rate of proliferation as well as protein deposition (i.e., protein synthesis and degradation). Previous studies and some recent ones indicate that low birth weight littermates in mice are born with fewer satellite cells and studies on pigs show that the rate of satellite cell proliferation may vary within litters. Proteomics studies show that protein synthesis and degradation is downregulated in IUGR pigs and low birth weight pigs also produce meat with less tenderness. Alternative maternal feeding strategies to prevent IUGR have been examined. Increasing maternal global nutrition had no beneficial effect on performance and muscle growth traits in several studies. Feeding excess maternal dietary protein also did not influence muscle growth traits whereas moderately decreased maternal dietary protein may decrease muscle fiber number and performance. On the other hand, addition of L-carnitine to the maternal gestation or lactation diet may increase birth and weaning weights or the muscle fiber number, respectively, in low birth weight pig offspring. Finally, promising data have been obtained on reproductive traits in pigs after addition of functional AA, such as arginine and glutamine, to the gestational diet. Although much is known about the biological basis of IUGR, we still need to learn much more about the mode of action before maternal dietary strategies can be developed to prevent IUGR.

Fetal and neonatal programming of postnatal growth and feed efficiency in swine

“…IUGR has permanent negative impacts on organ structure, neonatal adjustment, preweaning survival, postnatal growth, feed efficiency, lifetime health, skeletal-muscle composition, excessive accumulation of WAT, meat quality, reproductive performance, and the onset of adult diseases [14, 42]. Altered organ mass and structure, such as reduced numbers of pancreatic islets, reduced numbers of kidney glomeruli, or reduced numbers of muscle fibers, is one of the consequences of fetal programming and is equally important to functional consequences.…”

“… a Hypertrophy is defined as an increase in the size of the skeletal-muscle cell (also known as fiber), whereas hyperplasia refers to an increase in the number of cells or fibersAdapted from Dwyer et al [66], Handel and Stickland [65], Nissen et al [61], and Oksbjerg et al [42]…”

“…Adapted from Dwyer et al [66], Handel and Stickland [65], Nissen et al [61], and Oksbjerg et al [42]…”

Effect of birth weight, litter size and nipple position on growth of pigs during lactation and fattening

“…El incremento del tamaño de camada resulta desfavorable para la sobrevivencia y la vitalidad del lechón (1) , por lo que tiene un impacto negativo en la mortalidad pre-destete (2) , el peso al nacimiento y la uniformidad en la camada, aspecto de suma importancia en la sobrevivencia del lechón (3,4) . Es claro que el incremento en el tamaño de la camada, disminuye la media de peso al nacer y aumenta la proporción de lechones de bajo peso al nacimiento (5) .…”

“…Lo anterior concuerda con reportes que indican que los lechones de bajo peso al nacimiento, tienen una alta probabilidad de mortalidad, debido al aplastamiento y la Cuadro 1. Tiempo promedio de aseguramiento de pezón según la categoría de peso y el número de parto (3,17) . Sin embargo, es importante considerar que no necesariamente un lechón de categoría de bajo peso será una baja.…”