Abstract
This study examined the effect of linseed and algae on growth and carcass parameters, adipocyte cellularity, fatty acid profile and meat quality and gene expression in subcutaneous and intramuscular adipose tissues (AT) in lambs. After weaning, 33 lambs were fed three diets up to 26.7 ± 0.3 kg: Control diet (barley and soybean); L diet (barley, soybean and 10% linseed) and L-A diet (barley, soybean, 5% linseed and 3.89% algae). Lambs fed L-A diet showed lower average daily gain and greater slaughter age compared to Control and L (P < 0.001). Carcass traits were not affected by L and L-A diets, but a trend towards greater adipocyte diameter was observed in L and L-A in the subcutaneous AT (P = 0.057). Adding either linseed or linseed and algae increased α-linolenic acid and eicosapentaenoic acid contents in both AT (P < 0.001); however, docosahexaenoic acid was increased by L-A (P < 0.001). The n-6/n-3 ratio decreased in L and L-A (P < 0.001). Algae had adverse effects on meat quality, with greater lipid oxidation and reduced ratings for odor and flavor. The expression of lipogenic genes was downregulated in the subcutaneous AT (P < 0.05): acetyl-CoA carboxylase 1 (ACACA) in L and L-A and lipoprotein lipase (LPL) and stearoyl-CoA desaturase (SCD) in L-A. Fatty acid desaturase 1 (FADS1), fatty acid desaturase 2 (FADS2) and fatty acid elongase 5 (ELOVL5) were unaffected. In the subcutaneous AT, supplementing either L or L-A increased peroxisome proliferator-activated receptor gamma (PPARG) and CAAT-enhancer binding protein alpha (CEBPA) (P < 0.05), although it had no effect on sterol regulatory element-binding factor 1 (SREBF1). In the intramuscular AT, expression of ACACA, SCD, FADS1 and FADS2 decreased in L and L-A (P < 0.001) and LPL in L (P < 0.01), but PPARG, CEBPA and SREBF1 were unaffected.
Highlights
Adipose tissue (AT) amount and fatty acid (FA) composition play major roles in meat quality in terms of sensory properties and health considerations [1]
In the SC AT, greater expression of peroxisome proliferator-activated receptor gamma (PPARG) and CAAT-enhancer binding protein alpha (CEBPA) in L and linseed and algae group (L-A) group lambs agree with the results reported by Ebrahimi et al [40], who observed that supplementing linseed oil (0.4 or 1.3% DM) increased the PPARG expression in SC AT of growing goats, and by Kronberg et al [41], who demonstrated a significant increase in PPARG mRNA level as a result of an increased n-3 FA levels in bovine muscle
The results indicate that feeding linseed did not affect growth parameters of Navarra breed lambs; the partial substitution of linseed with marine algae reduced average daily gain (ADG) and increased slaughter age of lambs
Summary
Adipose tissue (AT) amount and fatty acid (FA) composition play major roles in meat quality in terms of sensory properties and health considerations [1]. Linseed addition has been found to be effective in increasing the ALA content of meat, there was no or was minor, effect on EPA, DHA and CLA [5,6] probably due to dietary PUFA inhibiting the expression of lipogenic genes and proteins involved in their synthesis [7,8]. Following the hypothesis that addition of PUFA to the diet in lamb feeds could alter FA composition, AT development and lipogenic gene expression, this work aimed to study the effect of linseed or the effect of partial substitution of linseed with marine algae on AT development, FA profile, adipogenic and lipogenic genes expression in subcutaneous (SC) and intramuscular (IM) AT and meat quality in lambs
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