| Sažetak | Kakvoća i hranjiva vrijednost goveđeg mesa u značajnoj su mjeri određene sadržajem masti u
trupu i mesu te udjelom zasićenih i nezasićenih masnih kiselina u masnom tkivu. Dosadašnja
istraživanja u značajnoj su mjeri usredotočena na utvrđivanje učinaka negenetskih (hranidbe,
smještaja) i genetskih čimbenika na odlike fenotipa goveda u proizvodnji mesa, uključujući i
kakvoću mesa koja je značajno determinirana sadržajem i strukturom masnog tkiva. Sadržaj
masnih kiselina u mesu pobuđuje interes potrošača radi određenih potencijalnih zdravstvenih
učinaka te uvjetovanih senzornih učinaka. Nedavna istraživanja pretpostavila su više
potencijalnih gena koji utječu na odlaganje i metabolizam masti. Mogućnost neposrednog
djelovanja na kakvoću goveđeg mesa protežiranjem poželjnih alelnih varijanti kandidat gena
poticaj je predmetnom istraživanju. Cilj rada bio je utvrditi povezanost polimorfizma FASN,
SCD i GH gena sa sadržajem masti i masnih kiselina u mesu junadi. Istraživanje je provedeno
na 104 jedinke različitih genotipova (križanci Holstein pasmine s bikovima četiriju mesnih
pasmina, Belgian Blue, Piemontese, Limousin i Simmental; te junad čistokrvnih pasmina
Simmental, Hereford i Charolais pasmine). Junice su klane u dobi od 14 do 15 mjeseci, muška
junad u dobi od 19 do 20 mjeseci. Nakon klaoničke obrade trupova izvršena je ocjena
konformacije i prekrivenost masnim tkivom, a između 12. i 13. rebra izmjerena je debljina
supkutanog masnog tkiva i uzet uzorak MLD-a u svrhu određivanja sadržaja masnih kiselina.
Izolacija genomske DNA obavljena je GenELute Blood Genomic DNA kitom, a nakon PCR
umnažanja kodogene sekvence, detekcija alelnih varijanti FASN, SCD i GH gena učinjena
neposredno na gelu nakon cijepanja fragmenta restrikcijskim endonukleazama. Različitosti u
EUROP ocjeni zamašćenosti utvrđene su između GH-CG genotipa u odnosu na GH-CC/GG
(p=0,029), dok je sadržaj masnog i vezivnog tkiva SCD-CT gena imao veću vrijednost u
odnosu na SCD-TT/CC (p=0,044). Značajni utjecaj alelnog polimorfizma FASN gena utvrđen
je na sadržaj C24:1 n-9 i C22:2 n-6 masnih kiselina, sadržaj SFA te odnos ꞷ-6/ꞷ-3 masnih
kiselina. Zapažen je značajan utjecaj polimorfizma SCD gena na sadržaj C15:0, C17:0,
C18:2 n-6 i C18:3 n-3 masnih kiselina te na zbirne udijele SFA. Polimorfizam GH gena
značajno je utjecao na sadržaj C16:0 i C20:1 n-9 masnih kiselina te omjer ꞷ-6/ꞷ-3 masnih
kiselina. Istraživanjem je potvrđen određeni utjecaj polimorfizma FASN, SCD i GH gena na
sadržaj i zbirne udjele manjeg broja masnih kiselina. Utvrđeni učinci alelnih varijanti FASN,
SCD i GH gena podloga su za nastavak istraživanja na većem broju jedinki i drugim
genotipovima goveda uključenim u proizvodnju goveđeg mesa. |
| Sažetak (engleski) | Beef meat is generally considered a valuable source of nutrients. The quality and nutritional
value of beef is determined by the fat content and the content of fatty acids. Beef is a source
of desirable omega-3 and omega-6 polyunsaturated fatty acids. Since the quality of the meat
and the content of the beef carcass are influenced by genetic and environmental factors,
numerous studies have been conducted with the aim of changing and improving the content
of fatty acids. Conducted genetic research has hypothesized several potential genes that affect
fat storage and metabolism. The aim of the work was to determine the association of FASN,
SCD and GH gene polymorphisms with the content of fat and fatty acids in beef. The research
was conducted on 104 individuals. For the purposes of the research, Holstein cows were
crossed with bulls of four beef breeds (Belgian Blue, Piemontese, Limousin and Simmental),
while Simmental, Hereford and Charolais were selected from purebred breeds. The heifers
were slaughtered at the age of 14 to 15 months and the bulls at the age of 19 to 20 months.
At 24-hour post-mortem processing of the carcasses, conformation and fat coverage was
evaluated. The subcutaneous fat tissue thickness was measured with a calliper over the m.
longissimus dorsi over the 12th and 13th rib at a point three-fourths of the length of the ribeye
from the split chine bone. Approximately 20 g of subcutaneous fat tissue was taken to
determine subcutaneous fatty acid composition and total lipids, while 100 g of MLD for the total
fatty acid composition. Extraction of DNA was carried out from blood using Blood Genomic
DNA kit. Detection of the FASN, SCD and GH polymorphism included PCR amplification and
subsequent digestion at 37 °C for 4 hours using MscI, Fnu4HI and Alui restriction
endonuclease, respectively. The allele and genotype frequencies were determined, while
statistical analysis was performed by general linear model.
No significant effect on carcass fat was observed among FASN genotypes. The FASN-AA
genotype had the lowest EUROP fat grade, subcutaneous adipose tissue thickness, MLD fat
content and fat/connective tissue percentage in 9th -11th part of the ribs. It was not determined
that other combinations of genotypes significantly affect carcass thickness and fatness,
although the p-values indicate certain relationships where the FASN-AA genotype has a lower
carcass fat value compared to the FASN-GG/GA genotypes and the FASN-GG genotype
(p=0.153 and p=0.211) and fat in MLD (p=0.438; p=0.366). In the SCD genotype, fat, and
connective tissue in the cross-section of the ribs had the highest value in the SCD-TT genotype
compared to the SCD-CC and SCD-CT genotypes (TT > CC > CT; p<0.100). However, a
significant difference (p=0.049) was observed between SCD-TT versus SCD-CT/CC
genotypes and between heterozygous SCD-CT versus SCD-TT/CC homozygous genotypes.
EUROP fat grade in GH genotypes had a high level of significance (p=0.053) with the highest
proportion of fat in the heterozygous GH-CG genotype (CG > CC > GG). It was also determined
that the fat content in the carcass was significantly lower in the heterozygous GH-GC genotype
compared to the GH-CC/GG genotypes (p=0.029). A significant difference between the content
of fat and connective tissue, with a higher value found in the GH-CC genotype compared to
the GH-CG/GG genotypes (p=0.046). Also, a difference was found between the content of fat
and connective tissue in the heterozygous GH-GC genotype compared to the homozygous
GH-CC/GG genotypes (p=0.034).
A significant influence of docosahexaenoic fatty acid was found in FASN-AA genotype
(p=0.024), while docosadiene had a significant influence in FASN-GG genotype compared to
GA/AA genotypes (p=0.009). FASN-GG genotype had a significant value of SFA (p=0.033)
and omega-6/omega-3 ratio (p=0.008). Nondecenoic (p=0.012), eicosadiene (p=0.002) and
docosahexaenoic (p=0.005) fatty acids were statistically more significant in the FASN-AA
genotype compared to the FASN-GA/GG genotypes, which was evident with nondecenoic acid
and in the FASN-GG/AA ratio (p=0.036) of homozygous FASN gene genotypes compared to
FASN-AA genotype. comparing only homozygous types of the FASN gene, the FASN-AA
genotype had a significant value for eicosadiene (p=0.013) and docosadiene (p=0.005) fatty
acids, but also for the ratio of omega-6/omega-3 fatty acids (p=0.014). The SCD-CC/TT
genotype had a significant influence of pentadecanoic (p=0.049) and heptadenoic (p=0.020)
fatty acids compared to the SCD-TT genotype, behenic fatty acid had a significant influence in
the SCD-TT genotype (p=0.002), as well as total shares of PUFA (p=0.043), omega-3
(p=0.042) and omega-6 (p=0.044) fatty acids, while linoleic (p=0.029), α-linolenic (p=0.028)
and total shares of SFA (p=0.029) had SCD-CC genotype. The results of the comparison of
homozygous genotypes of the SCD gene showed significant values of PUFA (p=0.043),
omega-3 (p=0.042), omega-6 (p=0.044) and the ratio of PUFA/MUFA (p=0.039) fatty acids in
SCD-TT genotype.
GH-CG genotype had a significant value (p=0.039) of palmitic, while GH-GG (p=0.034) had
eicosane fatty acids, and GH-CC genotype (p=0.048) omega-6/omega-3 fatty acid ratio. A
significant value of palmitic (p=0.018), non-decanoic (p=0.039) and eicosenoic (p=0.010) fatty
acids was shown by the GH-GG/GC genotype compared to the GH-CC genotype, which was
confirmed by comparing the heterozygous GH-GC genotype compared to homozygous GHGG/CC genotypes where nondecanoic acid had a significant p-value (p=0.040). The results of
the comparison of only homozygous genotypes of the GH gene showed a significant value of
eicosane fatty acid (p=0.044) in the dominant GH-GG genotype, while the ratio of omega6/omega-3 fatty acids was significant in the GH-CC genotype (p=0.048).
This research did not establish a significant increase in the content of saturated fatty acids in
the muscle and subcutaneous fat tissue of beef cattle, but a significant influence (p<0.05) of
FASN, SCD and GH gene polymorphisms on individual fatty acids and on the total proportion
of unsaturated fatty acids was determined. Based on the results of the research in question, it
is possible to conclude that more favourable quotients of polyunsaturated fatty acids and ratios
of ꞷ-6/ꞷ-3 fatty acids were determined in the meat of the researched animals. The obtained
research results are significantly different from the authors mentioned in the paper itself,
although the methods used are very similar or identical to those of fellow researchers. One of
the possible reasons may be in the allele frequencies and genotypes of the FASN, SCD and
GH genes, certainly the sampling itself (number of samples) and the methodology of work and
data processing. The explanation of the obtained results of various studies can be that
polymorphisms of the FASN, SCD and GH genes did not significantly affect the composition
of fatty acids, that the markers are not strong enough (informative) if crossbreeds are used in
the research (due to the different frequency of allelic variants), while a small number of breeds
and the number of sampled individuals should be increased in order to make the research
even more extensive and complex. In any case, this research laid a good foundation for further
expansion of the study of the mentioned genes and their influence of polymorphism on the
composition of fat and fatty acids in beef meat. |
