The forage type (grazing versus hay pasture) fed to ewes and the lamb sex affect fatty acid profile and lipogenic gene expression in the longissimus muscle of suckling lambs1

Abstract

Meat intramuscular fat (IMF) contributes to meat quality and consumer acceptance. Molecular events that occur during IMF deposition and the identification of genes that are differentially expressed during this process are important to the design of an optimal nutrition plan for animals. In the present study, we examined the effect of the forage type (grazing vs. hay pasture) fed to ewes and the effect of lamb sex on the LM fatty acid (FA) profile and gene expression of suckling lambs (10 to 12 kg of BW at slaughter); ewes received pasture hay (PH) or grazed pasture (GRE). Forage type had a significant effect on IMF FA profile. Ewes grazing green forage (GRE) promoted the formation and deposition of vaccenic acid (C18:1n-7), CLA, and PUFA n-3 in LM from their suckling lambs (P < 0.05). We found that forage type affected the expression of the sterol regulatory element binding transcription factor 1 (SREBF1) gene in females. However, in males, it modulated stearoyl CoA desaturase (SCD) gene expression (P < 0.05). Moreover, our results showed that females, independent of the diet of the ewes (PH or GRE), are predisposed to develop fat and to upregulate the expression of key genes of transcriptional factors PPARA, CEBPB, SREBF1, and lipoprotein lipase (LPL) and SCD (P < 0.05). The data suggest that SREBF1, SCD, and most likely CEBPB gene expression in young suckling lambs is modulated by both lamb sex and forage type fed to ewes. Fatty acid indicators PUFA, n-6/n-3, CLA, and SFA are closely related to LPL, SCD, PPARA, and CEBPB gene expression depending on animal sex or the diet of ewes. This study suggests that grazing pasture affects FA composition promoting greater vaccenic, CLA, and total PUFA n-3 FA in female and male suckling lambs, and it is mediated through the regulation of lipogenic enzyme expression.

Influence of birth weight and gender on lipid status and adipose tissue gene expression in lambs

“…In contrast, and similar to the data herein, female lambs at 4 months postnatal had higher LPL gene expression (in perirenal and subcutaneous fat depots) and higher fat mass (omental and perirenal) than males, which was largely independent of variations in maternal nutrition during the periconception period (Rattanatray et al 2010). Furthermore, the intramuscular fatty acid profile of suckling female lambs at w5 weeks postnatal was associated with upregulated LPL expression relative to males of equivalent weight, which the authors suggest predisposes females to increased adiposity (Dervishi et al 2012). There are no reports on FASN expression in relation to IUGR or gender in lambs, but in studies of IUGR vs normal male rat offspring, generated by either maternal protein restriction (Guan et al 2005) or global nutrient restriction (Desai et al 2008), visceral fat FASN gene expression was increased in adult life in association with higher fat mass and hypertrophic adipocytes respectively.…”

Novel polymorphisms in the 5′UTR of FASN, GPAM, MC4R and PLIN1 ovine candidate genes: Relationship with gene expression and diet

“…The suckling lambs were allocated to four dietary treatments: Grazing alfalfa (ALF; n = 11); Grazing alfalfa with supplement for lambs (ALF + S; n = 11); Indoor lambs with grazing ewes (IND-GRE; n = 11) and Indoors (IND; n = 11) (Dervishi et al, 2010). The second one consisted in 48 lambs (males and females) from Churra Tensina breed whose ewes were subjected to two feed treatments: grazed pasture (GRE) or pasture hay (PH) (Dervishi et al, 2012).…”

“…Primer sequences, amplicon sizes, GenBank accession number and PCR conditions are described in Supplementary Table S1. The gene expression levels were determined using the comparative Ct method and the data normalized using the housekeeping genes recommended by Dervishi et al (2011Dervishi et al ( , 2012.…”

“…Total RNA extraction and posterior cDNA synthesis was carry out from approximately 500 mg of semitendinous muscle (SM) from 44 Rasa Aragonesa lambs (Dervishi et al, 2010) and longissimus dorsi (LD) from 48 Churra Tensina lambs (Dervishi et al, 2012).…”

“…Quantity and quality of meat intramuscular fat (IMF) that also contributes to meat quality and consumer acceptance is influenced by the environment, age, genetics and the animal feeding system (Scerra et al, 2007;Dervishi et al, 2012).…”