SNP discovery and association study for growth, fatness and meat quality traits in Iberian crossbred pigs

Iberian pigs and its crosses are produced to obtain high-quality meat products. The objective of this work was to evaluate a wide panel of DNA markers, selected by biological and functional criteria, for association with traits related to muscle growth, fatness, meat quality and metabolism. We used 18 crossbred Iberian pigs with divergent postnatal growth patterns for whole genome sequencing and SNP discovery, with over 13 million variants being detected. We selected 1023 missense SNPs located on annotated genes and showing different allele frequencies between pigs with makerdly different growth patterns. We complemented this panel with 192 candidate SNPs obtained from literature mining and from muscle RNAseq data. The selected markers were genotyped in 480 Iberian × Duroc pigs from a commercial population, in which phenotypes were obtained, and an association study was performed for the 1005 successfully genotyped SNPs showing segregation. The results confirmed the effects of several known SNPs in candidate genes (such as LEPR, ACACA, FTO, LIPE or SCD on fatness, growth and fatty acid composition) and also disclosed interesting effects of new SNPs in less known genes such as LRIG3, DENND1B, SOWAHB, EPHX1 or NFE2L2 affecting body weight, average daily gain and adiposity at different ages, or KRT10, NLE1, KCNH2 or AHNAK affecting fatness and FA composition. The results provide a valuable basis for future implementation of marker-assisted selection strategies in swine and contribute to a better understanding of the genetic architecture of relevant traits.

Maternal undernutrition and offspring sex determine birth-weight, postnatal development and meat characteristics in traditional swine breeds

Background

The aim of this study was to determine how maternal undernutrition during pregnancy and offspring birth-weight can affect the postnatal development of offspring under farm conditions, which may lead to consequences in its meat and carcass quality. The current study involved a total of 80 litters from Iberian sows fed a diet fulfilling daily requirements (n = 47; control) or providing 70% daily requirements (n = 33; underfed) from d 38 to d 90 of gestation when fetal tissue development begins. After birth, piglets born live were classified as low birth-weight (LBW; < 1 kg) and normal birth-weight (NBW; ≥1 kg). During the growing phase, 240 control and 230 underfed pigs (50% males and females) distributed by BW category and sex were studied until the slaughter.

Results

At birth and weaning, there were significant differences in all morphological measures and weight between NBW and LBW piglets as expected (P < 0.0005), but few effects of the gestational feed restriction. During the growing phase, NBW pigs continued with higher weight than LBW pigs on all the days of evaluation (P < 0.05), even though control-LBW-females and LBW-males showed a catch-up growth. However, underfed pigs showed slower growth and higher feed conversion ratio than control pigs (P < 0.0001) at 215 days old. Moreover, the average daily weight gain (ADWG) for the overall period was greater for NBW, male and control pigs than for their LBW, female and underfed pigs (P < 0.0001, P< 0.0005 and P< 0.05, respectively) and NBW pigs were slaughtered at a younger age than LBW pigs (P < 0.0001). After slaughtering, control pigs also had higher carcass yield and backfat depth than underfed pigs (P < 0.0005) and the maternal nutritional effect caused main changes in the polar lipid fraction of liver and loin. The fatty acid composition of loin in control pigs had higher C18:1n-9 and n-3 FA concentrations, as well as lower ∑n-6/∑n-3 ratio, than in underfed pigs (P < 0.005).

Conclusions

In brief, results showed that the effects of maternal nutritional restriction appeared and increased with offspring age, causing worse developmental patterns for underfed pigs than for control pigs.

Electronic supplementary material

The online version of this article (10.1186/s40104-018-0240-6) contains supplementary material, which is available to authorized users.

Efectos del sexo y edad gestacional sobre la composición de ácidos grasos de fetos de cerdo Ibérico expuestos a malnutrición materna

El crecimiento intrauterino retardado (CIR) es debido a un inadecuado aporte de oxígeno y/o nutrientes durante el desarrollo prenatal. La respuesta adaptativa de la descendencia es tiempo dependiente, pero además están aumentando las evidencias de que el sexo fetal ejerce un fuerte efecto modulador sobre dicha respuesta. El presente estudio pretendió determinar los efectos de la edad gestacional y el sexo fetal sobre la composición de ácidos grasos en tejidos no adiposos involucrados en la regulación metabólica durante el desarrollo de fetos con CIR. Para ello, se analizó la composición de ácidos grasos en hígado y músculo (longissimus dorsi) de fetos con CIR (obtenidos como consecuencia de una malnutrición materna) durante la gestación (día 70 vs. 90), así como el efecto del sexo (machos vs. hembras). La distribución final de los fetos muestreados fue de: 33 fetos a día 70 de gestación (13 hembras y 20 machos), y 23 fetos a día 90 (10 hembras y 13 machos). Tanto en hígado como en músculo, una mayor concentración de ácidos grasos saturados (SFA; P

Efecto del sexo y la restricción de crecimiento intrauterino en la composición de ácidos grasos en lechones ibéricos recién nacidos

La aparición de la restricción del crecimiento intrauterino es un evento espontáneo que influye negativamente en el desarrollo postnatal. Este efecto ha sido estudiado en cerdos, pero hay pocos datos sobre los cambios potenciales en la composición de ácidos grasos. Para este estudio se analizó la composición de ácidos grasos en el hígado y músculo (longissimus dorsi) de 43 lechones Ibérico x Duroc recién nacidos. Dieciséis de ellos fueron clasificados como lechones de normopeso al nacimiento (8 machos y 8 hembras, peso promedio 1402,2 ± 321 g) y 27 fueron identificados como lechones de bajo peso al nacimiento (14 machos y 13 hembras, peso promedio 635,7 ± 159,1 g P

Fetal growth-retardation and brain-sparing by malnutrition are associated to changes in neurotransmitters profile

The present study assesses possible changes in the levels of different neurotransmitters (catecholamines and indoleamines) in fetuses affected by nutrient shortage. Hence, we determined the concentration of catecholamines and indoleamines at the hypothalamus of 56 swine fetuses obtained at both 70 and 90days of pregnancy (n=33 and 23 fetuses, respectively). The degree of fetal development and the fetal sex affected the neurotransmitters profile at both stages. At Day 70, there were found higher mean concentrations of l-DOPA in both female and male fetuses with severe IUGR; male fetuses with severe IUGR also showed higher concentrations of TRP than normal male littermates. At Day 90 of pregnancy, the differences between sexes were more evident. There were no significant effects from either severe IUGR on the neurotransmitter profile in male fetuses. However, in the females, a lower body-weight was related to lower concentrations of l-DOPA and TRP and those female fetuses affected by severe IUGR evidenced lower HVA concentration. In conclusion, the fetal synthesis and use of neurotransmitters increase with time of pregnancy but, in case of IUGR, both catecholamines and indoleamines pathways are affected by sex-related effects.