The fatty acid (FA) composition in the intramuscular fat (IMF) of the musculus
longissimus dorsi (MLD) of Ile de France purebred lambs in two different
production systems in Slovakia was evaluated using gas chromatography. In the first production system,
lambs and ewes were assigned to pasture without access to concentrates (P).
In the second system, lambs and ewes were confined indoors with hay/silage and
access to concentrates (S). An analysis of variance with the following factors was employed: production
system, sex, and production system–sex interactions. The
proportions of arachidonic, eicosapentaeonic, docosapentaeonic, and
docosahexaenoic FAs, i.e. long-chain polyunsaturated FA (PUFA), were
significantly higher in P lambs (1.83, 0.82, 0.92, 0.29 g 100 g
In Slovakia, the breeding of meat and/or non-dairy dual-purpose sheep breeds that produce heavy lambs (carcass weight above 13 kg) is increasing. The proportion of these breeds ranges from 10 to 15 % of total number of sheep (from 37 to 55 thousand of a total 372 thousand animals in 2017). Lambs are produced using different production systems; however, knowledge about the effects of management and/or feed choice on lamb meat is only known for light lambs in Slovakia, with carcass quality, physicochemical characteristics, and fatty acid (FA) composition of light lambs having been previously studied (Margetín et al., 1993, 2014a, b).
Regardless of lamb type, research around the world is aimed at assessing the
quality of lamb meat with respect to evaluating the proportions of essential
FAs (linoleic acid and
Many studies have aimed at finding the potential benefits regarding the consumption of lamb meat (Mortimer et al., 2014; Ponnampalam et al., 2014). The emphasis of these studies has primarily been on assessing the proportions of n-6 PUFA and n-3 PUFA which are assumed to have anti-inflammatory effects and to help protect against autoimmune diseases (Simopoulos, 2002; McAfee et al., 2010; Swanson et al., 2012). According to Australian and European standards, lamb meat is assumed to be an important source of n-3 PUFA when it contains a minimum of 30 to 40 mg of long-chain n-3 PUFA (EPA or DHA) per 100 g of meat (Ponnampalam et al., 2014; Howes et al., 2015). Fisher et al. (2000), Arsenos et al. (2006), Sinanoglou et al. (2013), and Ponnampalam et al. (2014) have indicated that consumer preferences mainly depend on the eating quality and nutrient value of the meat. Fatty acids occurring in fat contribute to the nutrient value of meat; however, the proportions of these FAs depend on the production system and the lamb feed used. Díaz et al. (2002, 2005), Aurousseau et al. (2004, 2007a, b), Nuernberg et al. (2005, 2008), Daley et al. (2010), and Howes et al. (2015) have reported that the FA composition in milk and meat depends on both pasture and concentrates. FA composition may also depend on genotype, although the genetic component of phenotypic variance is believed to be of lesser influence (Santos-Silva et al., 2002; Komprda et al., 2012; Ponnampalam et al., 2014).
In the 1970s and 1980s, Ile de France, as a dual-purpose breed, was mainly kept in order to improve the meat and wool production of traditional breeds in Slovakia. However, since the 1990s the Ile de France breed has been oriented to meat production; lamb feeding systems based on hay/silage and concentrates and systems based on grazing have both been considered. Differences in diet have enabled lamb birth to be postponed from winter to spring and natural pasture to be used. However, until now, no study has aimed at comparing the FA composition between grazing lambs and lambs fed with hay/silage and concentrates in Slovakia. Therefore, the objective of this study was to compare the FA composition in the intramuscular fat separated from the musculus longissimus dorsi (MLD) between Ile de France lambs from the two abovementioned production systems.
A total of 40 Ile de France purebred lambs kept either on pasture (P) or in a
stable (S) were included in this experiment. Each group included 20 lambs: 13
males and 7 females. In the first production system, P lambs were born
indoors (in April) and were moved to pasture shortly after parturition; the lambs were not
separated from the ewes and were allowed to suckle milk. The lambs and ewes in this group were not fed
on concentrates or hay/silage. The pasture was natural and was enriched with
Lambs were slaughtered in authorised slaughter houses run by the National
Agricultural and Food Centre – Research Institute of Animal Production Nitra
and the Slovak University of Agriculture in Nitra (identical slaughtering procedure).
The average weights of P and S lambs at slaughter were
29.23
The animals used in this study were treated in accordance with the current regulations and standards issued by the Ministry of Agriculture and Rural Development of the Slovak Republic. Manipulation methods were in accordance with the ICLAS Ethics and Animal Welfare Committee.
Twenty-four hours after slaughter, meat samples were taken from the MLD between
the 9 and 13th vertebra. The analysis of the fatty acid (FA) composition in
the intramuscular fat (IMF) of the MLD was undertaken in the laboratory of the Institute
of Chemistry (Faculty of Natural Sciences) at Comenius University
in Bratislava. After removing the epimysium, 100 g of the MLD was minced,
vacuum packed, and stored at
A total of 70 FAs were identified. The hypocholesterolaemic
FA/hypercholesterolaemic FA ratio (
Data were evaluated using an analysis of variance and a general linear model procedure as implemented in SAS (2009). Factors including the production system (P lambs and S lambs), sex (males and females), and production system–sex interactions were studied. Least-squares means were compared using a Scheffe test.
Fatty acids in the intramuscular fat (g 100 g
PxS: interaction between production system and sex;
The composition of FAs identified in the IMF of the MLD as affected by production
system is shown in Table 1. This factor significantly influenced the
proportions of almost all of the FAs that were investigated. The prevailing individual
saturated FAs (SFA) were palmitic acid (PA), stearic acid (SA), and myristic
acid (MA). A crucial finding in this study was the significantly lower (
Regarding individual monounsaturated FAs (MUFA), a lower
(
Regarding individual polyunsaturated FAs (PUFA), the proportion of
essential linoleic acid (LA) was about twofold higher (
The composition of FAs as affected by sex is shown in Table 1. No significant
differences were found in the proportions of MA, PA, SA, lauric, and margaric acids between males and females.
Conversely, Arsenos et al. (2006) reported a significant difference in the proportion of SA dependent on
sex. Regarding individual MUFA, the highest significant difference
(
The production system–sex interaction differed significantly
(
Fatty acid groups (g 100g
The proportions of FA groups believed to affect human health (Wood et al.,
2003; Sinanoglou et al., 2013), their ratios, and indexes are shown in
Table 2. Lamb meat is assumed to be highly nutritious and easy digestible
(Milewski, 2006; Nuernberg et al., 2008). Some doubts about the health effects of the consumption
of red meat (including lamb meat) and its lipid composition have arisen due to the
relatively high proportion of SFAs and relatively low proportion of PUFAs
(McAfee et al., 2010; Howes et al., 2015). The proportion of the SFA group was
significantly higher (
The proportion of the PUFA group was significantly higher (
The ratios and indexes of FA groups as affected by production system are
shown in Table 2. According to Sinanoglou et al. (2013), these ratios and indexes are
important when assessing the nutrition value of lipids. The ratio of
PUFA
The proportions of the FA groups, their ratios, and indexes in dependence on
sex are shown in Table 2. The significant differences between males and
females (
In a similar fashion to the analyses of individual SFAs, the production system–sex interaction
had a significant influence (
From a nutrition and human health standpoint (with respect to higher proportions of PUFAs, e.g. mainly LC n-3 PUFA, CLA, and essential FA, and lower proportions of SFA), the meat of lambs assigned to pasture feeding with no concentrate supplement seems to be better than the meat of lambs assigned to grow in a stable with a diet based on hay, silage, and concentrates. Therefore, consumers are recommended to favour the meat of grazing lambs in spite of the fact that the market price of this meat may be higher owing to its higher quality.
Data are available from the corresponding author upon request.
MM designed the experiment, performed the statistical analysis, and contributed to the paper. MO prepared the paper. JM obtained the meat samples. RK carried out the gas chromatography analyses.
The authors declare that they have no conflict of interest.
This work was supported by the Slovak Research and Development Agency (contract no. APVV-0458-10), the Research and Development Operational Programme funded by the ERDF, the Comenius University in Bratislava Science Park (grant no. ITMS 26240220086), and the Ministry of Education, Science, Research and Sport of the Slovak Republic (project VEGA 1/0364/15). Thanks are due to laboratory staff of the Institute of Chemistry (Faculty of Natural Sciences) at Comenius University in Bratislava and the staff of the slaughter houses (National Agricultural and Food Centre – Research Institute of Animal Production Nitra and Slovak University of Agriculture in Nitra). Edited by: Steffen Maak Reviewed by: four anonymous referees