Association of the MTNR1A gene polymorphisms and seasonal reproduction in sheep

U radu je istraživan utjecaj polimorfizama na lokusu 606 i lokusu 612 MTNR1A gena na sezonsku poliestričnost ovaca. Ciljevi predmetnog istraživanja bili su: 1) utvrditi frekvencije genotipova i alelnih varijanti MTNR1A gena na pozicijama 606 i 612 referentne sekvence U14109, 2) utvrditi prisutnost polimorfizama na istraživanoj sekvenci drugog egzona MTNR1A gena, 3) utvrditi utjecaj polimorfizama MTNR1A gena na sezonsku poliestričnost, dob ovaca pri prvom janjenju i dužinu međujanjidbenog razdoblja. Prikupljanje biološkog materijala (krv, tkivo, dlaka) i reprodukcijskih pokazatelja ovaca provedeno je tijekom 2015. i 2016. godine na području Republike Hrvatske i Republike Slovenije ovisno o mjestu uzgoja pojedine pasmine. U Hrvatskoj su prikupljeni uzorci od hrvatskih autohtonih pasmina ovaca: cigaje, dalmatinske pramenke, dubrovačke ovce, istarske ovce, ličke pramenke i paške ovce, zatim uvezenih pasmina ovaca: istočnofrizijske ovce, romanovske ovce i Suffolka, dok su u lovištu nakon usmrćivanja (odstrela) prikupljeni uzorci muflona. U Sloveniji su prikupljeni uzorci od slovenske autohtone pasmine: bovške ovce. Izuzev plemenitih pasmina ovaca koje odlikuje produženo razdoblje pripusne sezone, preostale pasmine odlikuje sezonska pojava spolnog ciklusa te slove kao sezonski poliestrične. Ukupno je prikupljeno 439 uzoraka iz kojih je napravljena izolacija genomske DNK. Nakon izolacije genomske DNK sa specifičnim začetnim oligonukleotidima amplificiran je glavni dio drugog egzona MTNR1A gena dužine 824 bazna para koji je podvrgnut enzimatskoj razgradnji. Za detekciju polimorfizama na lokusima 606 i 612 korištena je RsaI odnosno MnlI restrikcijska endonukleaza. Genotipizacija uzoraka bila je sljedeća: CC, CT i TT na lokusu 606 prema RsaI restrikcijskoj endonukleazi te GG, GA i AA na lokusu 612 prema MnlI restrikcijskoj endonukleazi. U pet uzoraka svakog genotipa utvrđenog MnlI restrikcijskom endonukleazom određen je slijed nukleotida na ciljnom odsječku istraživane DNK i potvrđena prisutnost polimorfizama na istraživanim lokusima (606 i 612) te detektirano 6 dodatnih mutacija. Polimorfizam na lokusu 606 se očitovao prisutnošću citozina (alel C) umjesto timina (alel T), dok se polimorfizam na lokusu 612 očitovao prisutnošću gvanina (alel G) umjesto adenina (alel A). Preostalih šest mutacija bile su: G453T, G706A, G783A, G801A, C891T i C893A. Na lokusu 606 MTNR1A gena u muflona, romanovske i Suffolk pasmine utvrđene su visoke frekvencije alela C dok su u sezonski poliestričnih pasmina utvrđene veće frekvencije alela T. Na lokusu 612 u gotovo svih istraživanih pasmina ovaca, utvrđena je visoka frekvencija alela G (od 0,50 do 0,95) izuzev muflona u kojeg je utvrđena visoka frekvencija alela A (0,93). U istraživanih ovaca utvrđena su janjenja u svim istraživanim sezonama, a bez obzira na genotip na lokusu 606 i 612 najveći broj janjenja je utvrđen tijekom zime (61,89%). Po broju janjenja tijekom ljeta dominirali su homozigoti (CC/606; GG/612) i heterozigoti (CT/606; GA612) za oba promatrana lokusa. Rezultatima predmetnog istraživanja nije utvrđen statistički značajan utjecaj polimorfizama na lokusu 606 i lokusu 612 MTNR1A gena na sezonsku poliestričnost ovaca, dob pri prvom janjenju niti na prosječnu dužinu međujanjidbenog razdoblja. Prisutnost polimorfizama na lokusu 612 povoljno je djelovala na pojavu janjenja izvan uobičajene sezone (ljeto i/ili jesen) u cigaje, istarske ovce, ličke pramenke i romanovske ovce, zatim na janjenja s manjom dobi u cigaje, dalmatinske pramenke, istočnofrizijske ovce, ličke pramenke i romanovske ovce te na kraće međujanjidbeno razdoblje u cigaje, dubrovačke, istarske, istočnofrizijske i romanovske ovce.Seasonal reproduction is a common feature among various mammalian species of the temperate latitudes. Ewes are well known for seasonal breeding activity which usually appears at the end of summer or at the beginning of autumn and finish in late winter or at the very beginning of spring. The seasonality of reproductive activity in sheep breeds in temperate latitudes is controlled by the photoperiod. In sheep, short photoperiods stimulate pineal gland to synthesize hormone melatonin, while long photoperiods inhibit pineal gland in melanin synthesis. Therefore, melatonin inform animal on photoperiod changes and has stimulating effect on hypothalamus which release Gonadotropinreleasing hormone. Pituitary gland stimulated by hypothalamus release Luteinizing hormone which affects the growth of oocytes. In sheep melatonin exerts its function through specific MT1 G-protein receptor. Gene for this receptor (MTNR1A gene) is located on chromosome 26 and has two polymorphic sites at position 606 and 612 which are associated to aseasonal breeding activity. Considering that MTNR1A gene has been proposed as candidate gene for out of season breeding in sheep, present study evaluates the effects of polymorphisms at positions 606 and 612 on sheep seasonal reproduction. The objectives of the study were: 1) determine the frequency of genotypes and allele variants of MTNR1A gene at positions 606 and 612 (reference sequence U14109), 2) determine the presence of polymorphisms on the studied sequences on the second exon of MTNR1A gene, 3) determine the effect of MTNR1A gene polymorphisms on seasonal reproduction, age at first lambing and interval between lambing. Depending on breeding place the biological material (blood, tissue, hair) and sheep reproductive parameters were collected during 2015 and 2016 year in the area of Republic of Croatia and Republic of Slovenia. Samples of Croatian indigenous sheep breeds (Tsigai sheep, Dalmatian Pramenka, Dubrovnik sheep, Istrian sheep, Lika Pramenka sheep and Pag Island sheep), imported noble sheep breeds (East Friesian sheep, Romanov sheep and Suffolk), as well as mouflon (Ovis musimon) samples (from hunting grounds) were collected in Croatia. In Slovenia were collected samples of Slovenian indigenous breed: Bovec sheep. Except for noble sheep breeds which are characterized by a prolonged period of mating season, the rest of breeds express seasonal sexual activity and they are considered as seasonal polyestric sheep breeds. From 439 collected samples genomic DNA was extracted using GenElute® Mammalian Genomic DNA Miniprep Kit (Sigma-Aldrich). After DNA extraction, the main part of second exon MTNR1A gene was amplified using specific primers (forward: 5'-TGTGTTTGTGGTGAGCCTGG-3'; reverse: 3'ATTTGCGTTTGGGAGAGGTA-5') adopted from Messer et al (1997). Obtained sequence length was 824 base pairs which was then subjected to enzymatic resolution with RsaI and MnlI restriction endonucleases. Polymorphism at position 606 was detected using RsaI, while polymorphism at position 612 was detected using MnlI restriction endonucleases. Samples were genotyped as follows: CC, CT or TT on locus 606 and GG, GA or AA on the locus 612 of MTNR1A gene. In five samples of each genotype determined with MnlI restriction endonucleases nucleotide sequence were determined in the target sequence of investigated DNA and confirmed the presence of polymorphisms in the studied loci (606 and 612). Reproductive parameters were date of birth of studied animal and dates of all her lambing records. Season of birth and seasons of lambings were calculated on the basis of date of birth and dates of lambings. Date of birth and date of first lambing were used to determine length of interval (in days) required for animal to have first offspring. Dates of subsequent lambings were used to calculate the average interval between lambing. For genotype effects estimation on first lambing on loci 606 and 612 the following linear model was used: Y1ijklm = µ + tri + srj + pk + Gl + eijklm. For genotype effects estimation on interval between lambing on loci 606 and 612 the following linear model was used: Y2ijklmn = β0 + β1xijklmn + tri + srj + pk + Gl + eijklmn. Considering the length of restriction fragments observer on agarose gel under UV light all three genotypes were detected at locus 606 and 612 of the MTNR1A gene in studied populations. Genotype frequencies at locus 606 were: 0.26, 0.45 and 0.29 for CC, CT and TT, respectively. Genotype frequencies at locus 612 were: 0.46, 0.39 and 0.15 for GG, GA and AA, respectively. Allele frequencies were: 0.49 for C, 0.51 for T, 0.66 for G and 0.34 for A allele. Differences in determined genotype frequencies between mouflon and all studied sheep breeds were statistically significant at both loci (P<0.001; P<0.05). Also statistically significant differences in determined genotypes frequencies were found between investigated sheep breeds. High frequency of the allele C on locus 606 was determined in mouflon, Romanov and Suffolk breeds while seasonal polyestric sheep breeds had higher frequencies of allele T. The locus 612 in almost all studied sheep breeds revealed a high frequency of the allele G (0.50 to 0.95) except mouflon in which we identified a high frequency of allele A (0.93). The most frequent combinations of genotypes at position 606 and 612 were: CTGA (27.79%), TTGG (27.11% and CTGG (16.86%). The examined populations were in Hardy-Weinberg equilibrium for both loci, except for locus 612 in Bovec sheep (P<0.01) and on both loci (606 and 612) in Dubrovnik sheep (P<0.01). The polymorphism at locus 606 was expressed by the presence of cytosine (C allele) instead of thymine (T allele), while polymorphisms at loci 612 was expressed by the presence of guanine (G allele) instead of adenine (A allele). Except those two mutations another six mutation were detected at the investigated DNA sequence. Those six mutations were: G453T, G706A, G783, G801, C891T and C893A. The mutation in position G706A and C893A led to an amino acid change in position 220 and 282, while all other mutations were silent. Sheep lambing were recorded in all four seasons, and regardless of genotype the highest number of lambing was recorded in winter (61.89%). Although out of season (summer and fall) was recorded only 11% of lambing, ewes with homozygous (CC/606; GG/612) and heterozygous (CT/606; GA/612) genotype dominated. In spring lambing dominated genotype combination CTGA (32.37%), in summer genotypes CCGG, CTGG CTGA with 25% each, in fall genotypes TTGG and CTGA and in winter genotypes CTGA and TTGG. Age of first lambing regarding genotype at position 606 was very uniform from 513.8 days in genotype CC to 519 days in genotype TT. On the other side at position 612 animals with genotype AA needed 434.9 days to first lambing, animals with GG genotype 525.1 days and GA genotype 521.6 days. Differences between genotypes on both loci were not statistically significant. Combination CTAA had the most favourable effect on lower age at first lambing. Individuals with mentioned genotype lambed with average age of 375.5 days while individuals with CCGG genotype were the oldest at first lambing with 587.9 days. Average interval between lambing in observed genotypes were as follow: 360.4, 358.5 and 361.3 days in CC, CT and TT genotype and 359.3, 360.7 and 356.6 days in GG, GA and AA genotype, respectively. Differences between genotypes on both loci were not statistically significant. Combination of genotypes TTAA had the smallest interval between lambing of 352.3 days while genotype combination TTGA had the biggest lambing interval (394.1 days). In the end we can conclude that polymorphisms at loci 606 and 612 of MTNR1A gene were observed in studied populations. Despite the absence of statistically significant effect of genotypes at loci 606 and 612 on studied parameters some positive effect of MTNR1A gene polymorphisms in some sheep breeds were observed

Association of the MTNR1A gene polymorphisms and seasonal reproduction in sheep

U radu je istraživan utjecaj polimorfizama na lokusu 606 i lokusu 612 MTNR1A gena na sezonsku poliestričnost ovaca. Ciljevi predmetnog istraživanja bili su: 1) utvrditi frekvencije genotipova i alelnih varijanti MTNR1A gena na pozicijama 606 i 612 referentne sekvence U14109, 2) utvrditi prisutnost polimorfizama na istraživanoj sekvenci drugog egzona MTNR1A gena, 3) utvrditi utjecaj polimorfizama MTNR1A gena na sezonsku poliestričnost, dob ovaca pri prvom janjenju i dužinu međujanjidbenog razdoblja. Prikupljanje biološkog materijala (krv, tkivo, dlaka) i reprodukcijskih pokazatelja ovaca provedeno je tijekom 2015. i 2016. godine na području Republike Hrvatske i Republike Slovenije ovisno o mjestu uzgoja pojedine pasmine. U Hrvatskoj su prikupljeni uzorci od hrvatskih autohtonih pasmina ovaca: cigaje, dalmatinske pramenke, dubrovačke ovce, istarske ovce, ličke pramenke i paške ovce, zatim uvezenih pasmina ovaca: istočnofrizijske ovce, romanovske ovce i Suffolka, dok su u lovištu nakon usmrćivanja (odstrela) prikupljeni uzorci muflona. U Sloveniji su prikupljeni uzorci od slovenske autohtone pasmine: bovške ovce. Izuzev plemenitih pasmina ovaca koje odlikuje produženo razdoblje pripusne sezone, preostale pasmine odlikuje sezonska pojava spolnog ciklusa te slove kao sezonski poliestrične. Ukupno je prikupljeno 439 uzoraka iz kojih je napravljena izolacija genomske DNK. Nakon izolacije genomske DNK sa specifičnim začetnim oligonukleotidima amplificiran je glavni dio drugog egzona MTNR1A gena dužine 824 bazna para koji je podvrgnut enzimatskoj razgradnji. Za detekciju polimorfizama na lokusima 606 i 612 korištena je RsaI odnosno MnlI restrikcijska endonukleaza. Genotipizacija uzoraka bila je sljedeća: CC, CT i TT na lokusu 606 prema RsaI restrikcijskoj endonukleazi te GG, GA i AA na lokusu 612 prema MnlI restrikcijskoj endonukleazi. U pet uzoraka svakog genotipa utvrđenog MnlI restrikcijskom endonukleazom određen je slijed nukleotida na ciljnom odsječku istraživane DNK i potvrđena prisutnost polimorfizama na istraživanim lokusima (606 i 612) te detektirano 6 dodatnih mutacija. Polimorfizam na lokusu 606 se očitovao prisutnošću citozina (alel C) umjesto timina (alel T), dok se polimorfizam na lokusu 612 očitovao prisutnošću gvanina (alel G) umjesto adenina (alel A). Preostalih šest mutacija bile su: G453T, G706A, G783A, G801A, C891T i C893A. Na lokusu 606 MTNR1A gena u muflona, romanovske i Suffolk pasmine utvrđene su visoke frekvencije alela C dok su u sezonski poliestričnih pasmina utvrđene veće frekvencije alela T. Na lokusu 612 u gotovo svih istraživanih pasmina ovaca, utvrđena je visoka frekvencija alela G (od 0,50 do 0,95) izuzev muflona u kojeg je utvrđena visoka frekvencija alela A (0,93). U istraživanih ovaca utvrđena su janjenja u svim istraživanim sezonama, a bez obzira na genotip na lokusu 606 i 612 najveći broj janjenja je utvrđen tijekom zime (61,89%). Po broju janjenja tijekom ljeta dominirali su homozigoti (CC/606; GG/612) i heterozigoti (CT/606; GA612) za oba promatrana lokusa. Rezultatima predmetnog istraživanja nije utvrđen statistički značajan utjecaj polimorfizama na lokusu 606 i lokusu 612 MTNR1A gena na sezonsku poliestričnost ovaca, dob pri prvom janjenju niti na prosječnu dužinu međujanjidbenog razdoblja. Prisutnost polimorfizama na lokusu 612 povoljno je djelovala na pojavu janjenja izvan uobičajene sezone (ljeto i/ili jesen) u cigaje, istarske ovce, ličke pramenke i romanovske ovce, zatim na janjenja s manjom dobi u cigaje, dalmatinske pramenke, istočnofrizijske ovce, ličke pramenke i romanovske ovce te na kraće međujanjidbeno razdoblje u cigaje, dubrovačke, istarske, istočnofrizijske i romanovske ovce.Seasonal reproduction is a common feature among various mammalian species of the temperate latitudes. Ewes are well known for seasonal breeding activity which usually appears at the end of summer or at the beginning of autumn and finish in late winter or at the very beginning of spring. The seasonality of reproductive activity in sheep breeds in temperate latitudes is controlled by the photoperiod. In sheep, short photoperiods stimulate pineal gland to synthesize hormone melatonin, while long photoperiods inhibit pineal gland in melanin synthesis. Therefore, melatonin inform animal on photoperiod changes and has stimulating effect on hypothalamus which release Gonadotropinreleasing hormone. Pituitary gland stimulated by hypothalamus release Luteinizing hormone which affects the growth of oocytes. In sheep melatonin exerts its function through specific MT1 G-protein receptor. Gene for this receptor (MTNR1A gene) is located on chromosome 26 and has two polymorphic sites at position 606 and 612 which are associated to aseasonal breeding activity. Considering that MTNR1A gene has been proposed as candidate gene for out of season breeding in sheep, present study evaluates the effects of polymorphisms at positions 606 and 612 on sheep seasonal reproduction. The objectives of the study were: 1) determine the frequency of genotypes and allele variants of MTNR1A gene at positions 606 and 612 (reference sequence U14109), 2) determine the presence of polymorphisms on the studied sequences on the second exon of MTNR1A gene, 3) determine the effect of MTNR1A gene polymorphisms on seasonal reproduction, age at first lambing and interval between lambing. Depending on breeding place the biological material (blood, tissue, hair) and sheep reproductive parameters were collected during 2015 and 2016 year in the area of Republic of Croatia and Republic of Slovenia. Samples of Croatian indigenous sheep breeds (Tsigai sheep, Dalmatian Pramenka, Dubrovnik sheep, Istrian sheep, Lika Pramenka sheep and Pag Island sheep), imported noble sheep breeds (East Friesian sheep, Romanov sheep and Suffolk), as well as mouflon (Ovis musimon) samples (from hunting grounds) were collected in Croatia. In Slovenia were collected samples of Slovenian indigenous breed: Bovec sheep. Except for noble sheep breeds which are characterized by a prolonged period of mating season, the rest of breeds express seasonal sexual activity and they are considered as seasonal polyestric sheep breeds. From 439 collected samples genomic DNA was extracted using GenElute® Mammalian Genomic DNA Miniprep Kit (Sigma-Aldrich). After DNA extraction, the main part of second exon MTNR1A gene was amplified using specific primers (forward: 5'-TGTGTTTGTGGTGAGCCTGG-3'; reverse: 3'ATTTGCGTTTGGGAGAGGTA-5') adopted from Messer et al (1997). Obtained sequence length was 824 base pairs which was then subjected to enzymatic resolution with RsaI and MnlI restriction endonucleases. Polymorphism at position 606 was detected using RsaI, while polymorphism at position 612 was detected using MnlI restriction endonucleases. Samples were genotyped as follows: CC, CT or TT on locus 606 and GG, GA or AA on the locus 612 of MTNR1A gene. In five samples of each genotype determined with MnlI restriction endonucleases nucleotide sequence were determined in the target sequence of investigated DNA and confirmed the presence of polymorphisms in the studied loci (606 and 612). Reproductive parameters were date of birth of studied animal and dates of all her lambing records. Season of birth and seasons of lambings were calculated on the basis of date of birth and dates of lambings. Date of birth and date of first lambing were used to determine length of interval (in days) required for animal to have first offspring. Dates of subsequent lambings were used to calculate the average interval between lambing. For genotype effects estimation on first lambing on loci 606 and 612 the following linear model was used: Y1ijklm = µ + tri + srj + pk + Gl + eijklm. For genotype effects estimation on interval between lambing on loci 606 and 612 the following linear model was used: Y2ijklmn = β0 + β1xijklmn + tri + srj + pk + Gl + eijklmn. Considering the length of restriction fragments observer on agarose gel under UV light all three genotypes were detected at locus 606 and 612 of the MTNR1A gene in studied populations. Genotype frequencies at locus 606 were: 0.26, 0.45 and 0.29 for CC, CT and TT, respectively. Genotype frequencies at locus 612 were: 0.46, 0.39 and 0.15 for GG, GA and AA, respectively. Allele frequencies were: 0.49 for C, 0.51 for T, 0.66 for G and 0.34 for A allele. Differences in determined genotype frequencies between mouflon and all studied sheep breeds were statistically significant at both loci (P<0.001; P<0.05). Also statistically significant differences in determined genotypes frequencies were found between investigated sheep breeds. High frequency of the allele C on locus 606 was determined in mouflon, Romanov and Suffolk breeds while seasonal polyestric sheep breeds had higher frequencies of allele T. The locus 612 in almost all studied sheep breeds revealed a high frequency of the allele G (0.50 to 0.95) except mouflon in which we identified a high frequency of allele A (0.93). The most frequent combinations of genotypes at position 606 and 612 were: CTGA (27.79%), TTGG (27.11% and CTGG (16.86%). The examined populations were in Hardy-Weinberg equilibrium for both loci, except for locus 612 in Bovec sheep (P<0.01) and on both loci (606 and 612) in Dubrovnik sheep (P<0.01). The polymorphism at locus 606 was expressed by the presence of cytosine (C allele) instead of thymine (T allele), while polymorphisms at loci 612 was expressed by the presence of guanine (G allele) instead of adenine (A allele). Except those two mutations another six mutation were detected at the investigated DNA sequence. Those six mutations were: G453T, G706A, G783, G801, C891T and C893A. The mutation in position G706A and C893A led to an amino acid change in position 220 and 282, while all other mutations were silent. Sheep lambing were recorded in all four seasons, and regardless of genotype the highest number of lambing was recorded in winter (61.89%). Although out of season (summer and fall) was recorded only 11% of lambing, ewes with homozygous (CC/606; GG/612) and heterozygous (CT/606; GA/612) genotype dominated. In spring lambing dominated genotype combination CTGA (32.37%), in summer genotypes CCGG, CTGG CTGA with 25% each, in fall genotypes TTGG and CTGA and in winter genotypes CTGA and TTGG. Age of first lambing regarding genotype at position 606 was very uniform from 513.8 days in genotype CC to 519 days in genotype TT. On the other side at position 612 animals with genotype AA needed 434.9 days to first lambing, animals with GG genotype 525.1 days and GA genotype 521.6 days. Differences between genotypes on both loci were not statistically significant. Combination CTAA had the most favourable effect on lower age at first lambing. Individuals with mentioned genotype lambed with average age of 375.5 days while individuals with CCGG genotype were the oldest at first lambing with 587.9 days. Average interval between lambing in observed genotypes were as follow: 360.4, 358.5 and 361.3 days in CC, CT and TT genotype and 359.3, 360.7 and 356.6 days in GG, GA and AA genotype, respectively. Differences between genotypes on both loci were not statistically significant. Combination of genotypes TTAA had the smallest interval between lambing of 352.3 days while genotype combination TTGA had the biggest lambing interval (394.1 days). In the end we can conclude that polymorphisms at loci 606 and 612 of MTNR1A gene were observed in studied populations. Despite the absence of statistically significant effect of genotypes at loci 606 and 612 on studied parameters some positive effect of MTNR1A gene polymorphisms in some sheep breeds were observed

Association of the MTNR1A gene polymorphisms and seasonal reproduction in sheep

U radu je istraživan utjecaj polimorfizama na lokusu 606 i lokusu 612 MTNR1A gena na sezonsku poliestričnost ovaca. Ciljevi predmetnog istraživanja bili su: 1) utvrditi frekvencije genotipova i alelnih varijanti MTNR1A gena na pozicijama 606 i 612 referentne sekvence U14109, 2) utvrditi prisutnost polimorfizama na istraživanoj sekvenci drugog egzona MTNR1A gena, 3) utvrditi utjecaj polimorfizama MTNR1A gena na sezonsku poliestričnost, dob ovaca pri prvom janjenju i dužinu međujanjidbenog razdoblja. Prikupljanje biološkog materijala (krv, tkivo, dlaka) i reprodukcijskih pokazatelja ovaca provedeno je tijekom 2015. i 2016. godine na području Republike Hrvatske i Republike Slovenije ovisno o mjestu uzgoja pojedine pasmine. U Hrvatskoj su prikupljeni uzorci od hrvatskih autohtonih pasmina ovaca: cigaje, dalmatinske pramenke, dubrovačke ovce, istarske ovce, ličke pramenke i paške ovce, zatim uvezenih pasmina ovaca: istočnofrizijske ovce, romanovske ovce i Suffolka, dok su u lovištu nakon usmrćivanja (odstrela) prikupljeni uzorci muflona. U Sloveniji su prikupljeni uzorci od slovenske autohtone pasmine: bovške ovce. Izuzev plemenitih pasmina ovaca koje odlikuje produženo razdoblje pripusne sezone, preostale pasmine odlikuje sezonska pojava spolnog ciklusa te slove kao sezonski poliestrične. Ukupno je prikupljeno 439 uzoraka iz kojih je napravljena izolacija genomske DNK. Nakon izolacije genomske DNK sa specifičnim začetnim oligonukleotidima amplificiran je glavni dio drugog egzona MTNR1A gena dužine 824 bazna para koji je podvrgnut enzimatskoj razgradnji. Za detekciju polimorfizama na lokusima 606 i 612 korištena je RsaI odnosno MnlI restrikcijska endonukleaza. Genotipizacija uzoraka bila je sljedeća: CC, CT i TT na lokusu 606 prema RsaI restrikcijskoj endonukleazi te GG, GA i AA na lokusu 612 prema MnlI restrikcijskoj endonukleazi. U pet uzoraka svakog genotipa utvrđenog MnlI restrikcijskom endonukleazom određen je slijed nukleotida na ciljnom odsječku istraživane DNK i potvrđena prisutnost polimorfizama na istraživanim lokusima (606 i 612) te detektirano 6 dodatnih mutacija. Polimorfizam na lokusu 606 se očitovao prisutnošću citozina (alel C) umjesto timina (alel T), dok se polimorfizam na lokusu 612 očitovao prisutnošću gvanina (alel G) umjesto adenina (alel A). Preostalih šest mutacija bile su: G453T, G706A, G783A, G801A, C891T i C893A. Na lokusu 606 MTNR1A gena u muflona, romanovske i Suffolk pasmine utvrđene su visoke frekvencije alela C dok su u sezonski poliestričnih pasmina utvrđene veće frekvencije alela T. Na lokusu 612 u gotovo svih istraživanih pasmina ovaca, utvrđena je visoka frekvencija alela G (od 0,50 do 0,95) izuzev muflona u kojeg je utvrđena visoka frekvencija alela A (0,93). U istraživanih ovaca utvrđena su janjenja u svim istraživanim sezonama, a bez obzira na genotip na lokusu 606 i 612 najveći broj janjenja je utvrđen tijekom zime (61,89%). Po broju janjenja tijekom ljeta dominirali su homozigoti (CC/606; GG/612) i heterozigoti (CT/606; GA612) za oba promatrana lokusa. Rezultatima predmetnog istraživanja nije utvrđen statistički značajan utjecaj polimorfizama na lokusu 606 i lokusu 612 MTNR1A gena na sezonsku poliestričnost ovaca, dob pri prvom janjenju niti na prosječnu dužinu međujanjidbenog razdoblja. Prisutnost polimorfizama na lokusu 612 povoljno je djelovala na pojavu janjenja izvan uobičajene sezone (ljeto i/ili jesen) u cigaje, istarske ovce, ličke pramenke i romanovske ovce, zatim na janjenja s manjom dobi u cigaje, dalmatinske pramenke, istočnofrizijske ovce, ličke pramenke i romanovske ovce te na kraće međujanjidbeno razdoblje u cigaje, dubrovačke, istarske, istočnofrizijske i romanovske ovce.Seasonal reproduction is a common feature among various mammalian species of the temperate latitudes. Ewes are well known for seasonal breeding activity which usually appears at the end of summer or at the beginning of autumn and finish in late winter or at the very beginning of spring. The seasonality of reproductive activity in sheep breeds in temperate latitudes is controlled by the photoperiod. In sheep, short photoperiods stimulate pineal gland to synthesize hormone melatonin, while long photoperiods inhibit pineal gland in melanin synthesis. Therefore, melatonin inform animal on photoperiod changes and has stimulating effect on hypothalamus which release Gonadotropinreleasing hormone. Pituitary gland stimulated by hypothalamus release Luteinizing hormone which affects the growth of oocytes. In sheep melatonin exerts its function through specific MT1 G-protein receptor. Gene for this receptor (MTNR1A gene) is located on chromosome 26 and has two polymorphic sites at position 606 and 612 which are associated to aseasonal breeding activity. Considering that MTNR1A gene has been proposed as candidate gene for out of season breeding in sheep, present study evaluates the effects of polymorphisms at positions 606 and 612 on sheep seasonal reproduction. The objectives of the study were: 1) determine the frequency of genotypes and allele variants of MTNR1A gene at positions 606 and 612 (reference sequence U14109), 2) determine the presence of polymorphisms on the studied sequences on the second exon of MTNR1A gene, 3) determine the effect of MTNR1A gene polymorphisms on seasonal reproduction, age at first lambing and interval between lambing. Depending on breeding place the biological material (blood, tissue, hair) and sheep reproductive parameters were collected during 2015 and 2016 year in the area of Republic of Croatia and Republic of Slovenia. Samples of Croatian indigenous sheep breeds (Tsigai sheep, Dalmatian Pramenka, Dubrovnik sheep, Istrian sheep, Lika Pramenka sheep and Pag Island sheep), imported noble sheep breeds (East Friesian sheep, Romanov sheep and Suffolk), as well as mouflon (Ovis musimon) samples (from hunting grounds) were collected in Croatia. In Slovenia were collected samples of Slovenian indigenous breed: Bovec sheep. Except for noble sheep breeds which are characterized by a prolonged period of mating season, the rest of breeds express seasonal sexual activity and they are considered as seasonal polyestric sheep breeds. From 439 collected samples genomic DNA was extracted using GenElute® Mammalian Genomic DNA Miniprep Kit (Sigma-Aldrich). After DNA extraction, the main part of second exon MTNR1A gene was amplified using specific primers (forward: 5'-TGTGTTTGTGGTGAGCCTGG-3'; reverse: 3'ATTTGCGTTTGGGAGAGGTA-5') adopted from Messer et al (1997). Obtained sequence length was 824 base pairs which was then subjected to enzymatic resolution with RsaI and MnlI restriction endonucleases. Polymorphism at position 606 was detected using RsaI, while polymorphism at position 612 was detected using MnlI restriction endonucleases. Samples were genotyped as follows: CC, CT or TT on locus 606 and GG, GA or AA on the locus 612 of MTNR1A gene. In five samples of each genotype determined with MnlI restriction endonucleases nucleotide sequence were determined in the target sequence of investigated DNA and confirmed the presence of polymorphisms in the studied loci (606 and 612). Reproductive parameters were date of birth of studied animal and dates of all her lambing records. Season of birth and seasons of lambings were calculated on the basis of date of birth and dates of lambings. Date of birth and date of first lambing were used to determine length of interval (in days) required for animal to have first offspring. Dates of subsequent lambings were used to calculate the average interval between lambing. For genotype effects estimation on first lambing on loci 606 and 612 the following linear model was used: Y1ijklm = µ + tri + srj + pk + Gl + eijklm. For genotype effects estimation on interval between lambing on loci 606 and 612 the following linear model was used: Y2ijklmn = β0 + β1xijklmn + tri + srj + pk + Gl + eijklmn. Considering the length of restriction fragments observer on agarose gel under UV light all three genotypes were detected at locus 606 and 612 of the MTNR1A gene in studied populations. Genotype frequencies at locus 606 were: 0.26, 0.45 and 0.29 for CC, CT and TT, respectively. Genotype frequencies at locus 612 were: 0.46, 0.39 and 0.15 for GG, GA and AA, respectively. Allele frequencies were: 0.49 for C, 0.51 for T, 0.66 for G and 0.34 for A allele. Differences in determined genotype frequencies between mouflon and all studied sheep breeds were statistically significant at both loci (P<0.001; P<0.05). Also statistically significant differences in determined genotypes frequencies were found between investigated sheep breeds. High frequency of the allele C on locus 606 was determined in mouflon, Romanov and Suffolk breeds while seasonal polyestric sheep breeds had higher frequencies of allele T. The locus 612 in almost all studied sheep breeds revealed a high frequency of the allele G (0.50 to 0.95) except mouflon in which we identified a high frequency of allele A (0.93). The most frequent combinations of genotypes at position 606 and 612 were: CTGA (27.79%), TTGG (27.11% and CTGG (16.86%). The examined populations were in Hardy-Weinberg equilibrium for both loci, except for locus 612 in Bovec sheep (P<0.01) and on both loci (606 and 612) in Dubrovnik sheep (P<0.01). The polymorphism at locus 606 was expressed by the presence of cytosine (C allele) instead of thymine (T allele), while polymorphisms at loci 612 was expressed by the presence of guanine (G allele) instead of adenine (A allele). Except those two mutations another six mutation were detected at the investigated DNA sequence. Those six mutations were: G453T, G706A, G783, G801, C891T and C893A. The mutation in position G706A and C893A led to an amino acid change in position 220 and 282, while all other mutations were silent. Sheep lambing were recorded in all four seasons, and regardless of genotype the highest number of lambing was recorded in winter (61.89%). Although out of season (summer and fall) was recorded only 11% of lambing, ewes with homozygous (CC/606; GG/612) and heterozygous (CT/606; GA/612) genotype dominated. In spring lambing dominated genotype combination CTGA (32.37%), in summer genotypes CCGG, CTGG CTGA with 25% each, in fall genotypes TTGG and CTGA and in winter genotypes CTGA and TTGG. Age of first lambing regarding genotype at position 606 was very uniform from 513.8 days in genotype CC to 519 days in genotype TT. On the other side at position 612 animals with genotype AA needed 434.9 days to first lambing, animals with GG genotype 525.1 days and GA genotype 521.6 days. Differences between genotypes on both loci were not statistically significant. Combination CTAA had the most favourable effect on lower age at first lambing. Individuals with mentioned genotype lambed with average age of 375.5 days while individuals with CCGG genotype were the oldest at first lambing with 587.9 days. Average interval between lambing in observed genotypes were as follow: 360.4, 358.5 and 361.3 days in CC, CT and TT genotype and 359.3, 360.7 and 356.6 days in GG, GA and AA genotype, respectively. Differences between genotypes on both loci were not statistically significant. Combination of genotypes TTAA had the smallest interval between lambing of 352.3 days while genotype combination TTGA had the biggest lambing interval (394.1 days). In the end we can conclude that polymorphisms at loci 606 and 612 of MTNR1A gene were observed in studied populations. Despite the absence of statistically significant effect of genotypes at loci 606 and 612 on studied parameters some positive effect of MTNR1A gene polymorphisms in some sheep breeds were observed

Utjecaj spola i proizvodne sezone na sposobnost zadržavanja vode i sastav trupa janjadi istarske ovce.

The aim of this study was to determine influence of sex and slaughtering season on water-holding capacity and carcass composition in Istrian lambs, raised in a traditional farming system in the Istrian region. The study was carried out on a total of 32 lambs (16 males and 16 females) of Istrian breed, raised on a family farm, during the slaughtering season in 2010, 2011 and 2012. Female lambs had a significantly higher cooking loss (P≤0.05) and proportion of loin-rib (P≤0.05), while male lambs had a significantly higher head proportion(P≤0.05). Regarding tissue composition, it was found that in the loin-rib, female lambs had significantly higher fat content (P≤0.05) and lower muscle content (P≤0.05) than males. Slaughtering season significantly affected proportions of neck (P≤0.001), shoulder (P≤0.05), anterior rib (P≤0.001), loin-rib (P≤0.001), breast (P≤0.001), hind leg (P≤0.05) and kidney knob (P≤0.05). Furthermore, slaughtering season significantly affected (P≤0.05) the composition of individual cuts, i.e. muscle proportion in the neck, loin-rib, breast and hind leg, bone proportion in the neck, shoulder, anterior rib and hind leg, and fat proportion in all cuts. The results of this study indicated that male and female Istrian lambs, reared under similar conditions, had very similar expression of the investigated traits. Slaughtering season affected most of the traits related to carcass composition. In order to provide more uniform carcasses on the market, it is necessary to ensure similar quality of feeds during the unfavourable seasons.Cilj ovog istraživanja bio je utvrditi utjecaj spola i proizvodne sezone na sposobnost zadržavanja vode i sastav trupa janjadi istarske ovce. Janjad istarske ovce uzgojena je u skladu s tradicijskim načinom na obiteljskom poljoprivrednom gospodarstvu u Istarskoj županiji tijekom 2010., 2011. i 2012. godine. Za tu je svrhu nasumično odabrano 32 janjadi (16 muške i 16 ženske). U trupovima ženske janjadi utvrđen je značajno veći kalo kuhanja (P≤0,05) i udio leđa s rebrima (P≤0,05), dok je u trupovima muške janjadi utvrđen značajno veći udio glave (P≤0,05). Uz to, utvrđeno je da trupovi ženske janjadi u leđima s rebrima imaju značajno veći udio masnog tkiva (P≤0,05), dok trupovi muške janjadi imaju značajno veći udio mišićnog tkiva (P≤0,05). Proizvodna sezona je značajno utjecala na udio vrata (P≤0,001), ramenog dijela (P≤0,05), prednjeg dijela rebara (P≤0,001), leđa s rebrima (P≤0,001), grudi (P≤0,001), buta (P≤0,05) i bubrežnog masnog tkiva (P≤0,05). Nadalje, proizvodna sezona je značajno utjecala na sastav janjećeg trupa (P≤0,05), odnosno na udio mišića u vratu, leđima s rebrima, grudima i butu sa zdjeličnim dijelom, udio kosti u vratu, ramenom dijelu, prednjem dijelu rebara i butu te udio masti u svim dijelovima trupa. Rezultatima predmetnog istraživanja je utvrđeno da janjad istarske ovce koju se uzgaja u podjednakim uvjetima neovisno o spolu ima gotovo neznatne razlike u većini istraživanih svojstava. Proizvodna sezona je značajno utjecala na veći dio sastava janjećeg trupa. Stoga je, u cilju pružanja ujednačenih janjećih trupova na tržištu, potrebno osigurati podjednaku kakvoću krme i tijekom nepovoljnih proizvodnih sezona

Negenetski čimbenici morfoloških odlika vimena istarskih ovaca

Considering the facts that Istrian sheep is Croatian indigenous breed with the highest milk production, and increasing interest of local farmers for machine milking implementation, the aim of this study was to determine the factors affecting udder morphology traits of Istrian ewes. Ninetythree purebred Istrian ewes with symmetrical udders and no signs of clinical mastitis, from second to fourth lactation, were used for this study. Average udder depth of Istrian ewes was 15.85 cm, udder width 13.05 cm, udder circumference 39.66 cm, cistern height 1.44 cm, teat position 2.85 (scored from 1 to 5), teat angle 47.32°, teat length 3.43 cm and teat width 2.03 cm. The traits related to udder size (depth, width, and circumference) were significantly (P<0.01) affected by lactation milk yield. These traits were also in high and positive correlations (P<0.01) with daily milk yield. With the increase of parity, the morphological aptitude of udder to mechanical milking become worse, with an increase (P<0.01) of cistern height, teat angle and position. As lactation of Istrian ewes continued morphological traits defining udder aptitude for machine milking improved (decrease of cistern height, teat angle and position). Ewes with two and more lambs had larger udder (P<0.05) than ewes with a single lamb.S obzirom na činjenicu da je istarska ovca najmliječnija hrvatska izvorna pasmina ovaca te na sve veći interes uzgajivača za primjenom strojne mužnje, cilj ovog rada bio je utvrditi čimbenike morfoloških odlika vimena istarskih ovaca. Istraživanjem su bile obuhvaćene ukupno 93 čistokrvne istarske ovce, od druge do četvrte laktacije, sa simetrično razvijenim vimenom i bez znakova kliničkog mastitisa. Prosječna dubina vimena bila je 15,85 cm, širina vimena 13,05 cm, opseg vimena 39,66 cm, visina cisterne 1,44 cm, položaj sisa 2,85 (ocjena raspona od 1 do 5), kut sise 47,32°, duljina sise 3,43 cm i širina sise 2,03 cm. Odlike vezane uz veličinu vimena (dubina, širina i opseg vimena) bile su pod značajnim utjecajem (P<0,01) količine mlijeka proizvedenoga u laktaciji. Također, ove odlike su bile u visokoj i pozitivnoj korelaciji (P<0,01) sa dnevnom proizvodnjom mlijeka. S povećanjem redoslijeda laktacije prikladnost vimena strojnoj mužnji je narušena, s posljedičnim povećanjem (P<0,01) visine cisterne, kuta i položaja sisa. S odmicanjem laktacije utvrđeno je poboljšanje prikladnosti vimena strojnoj mužnji (smanjenje visine cisterne te kuta i položaja sisa). Ovce s dvoje i više ojanjene janjadi imale su veće (P<0,05) i razvijenije vime nego ovce s jednim janjetom

SOME MEAT TRAITS OF LIKA PRAMENKA LAMBS

Cilj ovog istraživanja bio je utvrditi porodnu masu i prosječni dnevni prirast janjadi ličke pramenke u razdoblju od partusa do klanja (prodaje), odnosno navršene dobi od 127 dana. Istraživanje je provedeno na poljoprivrednom gospodarstvu Obućina koje se desetljećima bavi uzgojem ovaca ličke pramenke i proizvodnjom janjećeg mesa. Istraživanjima je bilo obuhvaćeno ukupno 101 janje (55 ženske i 46 muške, odnosno 83 samaca i 18 blizanaca). U svrhu utvrđivanja porodne mase, janjad je vagana odmah nakon partusa (MASA1), zatim pri prosječnoj dobi od 48 dana (MASA2) te prosječnoj dobi od 127 dana (MASA3). Na osnovu utvrđenih tjelesnih masa janjadi izračunati su prosječni dnevni prirasti i to: DP1 (od partusa do 48.-og dana) DP2 (od 48.-og do 127.-og dana) te DP3 (od partusa do dobi od 127 dana). Utvrđena je prosječna porodna masa janjadi ličke pramenke od 3,19 kg. Prosječne vrijednosti utvrđenih dnevnih prirasta bile su: DP1 202,29 g; DP2 158,61 g; a DP3 173,84 g. Utvrđen je statistički značajan utjecaj veličine legla na tjelesnu masu (P<0,05) i prosječni dnevni prirast janjadi (P<0,001) ličke pramenke. Iako je muška janjad neposredno nakon partusa bila teža od ženske utvrđene razlike nisu bile statistički značajne (P≥0,5). Također, spol janjadi nije statistički značajno utjecao na prosječni dnevni prirast janjadi u početku tova (DP1), dok su dnevni prirast u drugoj fazi (DP2) i ukupni prosječni dnevni prirast (DP3) bili pod statistički značajnim utjecajem spola (P<0,01; P<0,05). Muška janjad je imala značajno veći DP2 i veći DP3 od ženske janjadi.The aim of this research was to determine birth weight and average daily gain of Lika Pramenka lambs from birth to slaughter (sale), or the reached age of 127 days. The research was conducted on a family farm Obućina which for decades occupy with rearing of Lika Pramenka sheep and lamb meat production. The research included a total of 101 lambs (55 female and 46 male and 83 singles and 18 twins). In order to determine birth weight, lambs were weighted immediately after birth (MASS1), then at an average age of 48 days (MASS2) and at an average age of 127 days (MASS3). Based on the determined body weights of lambs average daily gains were calculated: DG1 (from birth to 48th day), DG2 (from 48th to 127th day) and DG3 (from birth to age of 127th day). The average birth weight of Lika Pramenka lambs of 3.19 kg was determined. Average values of determined daily gains were: DG1 202.29 g; DG2 158.61g; and DG3 173.84g. It was determined statistically significant effect of litter size on body weight (P<0.05) and average daily gain (P<0.001) of Lika Pramenka lambs. Although male lambs immediately thereafter births were heavier then female, determined differences were not statistically significant (P≥0.5). Likewise, lambs gender didn\u27t statistically significant influenced on average daily gain of lambs at the begining of fatening (DG1), when daily gains in second phase (DG2) and total average daily gain (DG3) were statistically significant influenced by lambs gender (P<0.01; P<0.05). Male lambs had significantlly higher DG2 and DG3 then female lambs

THE REPRODUCTIVE TRAITS OF MILK GOATS IN REPUBLIC OF CROATIA

Plemenite pasmine koza (alpina, sanska i srnasta koza) primarno su namijenjene proizvodnji mlijeka, ali zbog dobrih reprodukcijskih odlika i zadovoljavajućih prosječnih dnevnih prirasta važne su i za proizvodnju jarećeg mesa. Reprodukcijske odlike u velikoj mjeri utječu na rentabilnost svake stočarske proizvodnje pa tako i kozarstva. Cilj ovog rada bio je utvrditi prosječne veličine legla, omjer spolova te utjecaj pasmine, spola, veličine legla i redoslijeda jarenja na porodnu masu jaradi. Podaci potrebni za provedbu ovog istraživanja preuzeti su iz središnje baze podataka Hrvatske poljoprivredne agencije. Istraživanjima je bilo obuhvaćeno ukupno 3 775 jaradi iz trogodišnjeg vremenskog razdoblja i to: 2 890 alpina, 542 srnaste i 343 sanske pasmine. U leglima alpina i sanske pasmine evidentiran je veći udio ženske jaradi u svim jarenjima (od prvog do petog), dok je u srnate pasmine utvrđen znatno veći udio muške jaradi. U leglima sanske i srnaste pasmine bilo je najviše samaca, zatim blizanaca i trojki, dok je u alpine bilo najviše dvojaka, zatim samaca i trojki. Najveća prosječna porodna masa utvrđena je u alpina jaradi (3,44 kg), a najmanja u jaradi srnaste pasmine (2,84 kg). U sve tri istraživane pasmine utvrđena je znatno veća porodna masa muške u odnosu na žensku jarad. Najveća prosječna porodna masa utvrđena je u samaca, a s povećanjem veličine legla porodna masa jaradi se smanjivala. Utvrđen je statistički značajan utjecaj (P<0,0001) pasmine, spola, veličine legla i redoslijeda jarenja na porodnu masu jaradi.Noble goat breeds (Alpine, Saanen, German Improved Fawn) primary are intended for milk production, but because of the good reproductive characteristics and satisfactory average daily gains they are also important for goat kid meat production. Reproductive characteristics largely affect the profitability of each livestock production including goat breeding. The aim of this study was to determine the average litter size, sex ratio and the effect of breed, sex, litter size and the order of kidding on the birth weight of kids. Data required for the implementation of this study were obtained from the central database of Croatian Agricultural Agency. The studies included a total of 3775 kids from the three-year period as follows: 2890 Alpine, 542 Fawn and 343 Saanen breed. In litters of Alpine and Saanen breeds it was recorded higher proportion of female goat kids in all kidding’s (from first to fifth), while significantly higher proportion of male goat kids was found in Fawn breed. In Saanen’s and Fawn’s litters it was the most singles, then twins and triplets, while in the Alpine’s it was the most twins, then the singles and triples. The highest average birth weight was determined in Alpine goat kids (3.44 kg), and lowest in Fawn goat kids (2.84 kg). In all three investigated breeds considerably greater birth weight of male goat kids compared to female goat kids was determined. The highest average birth weight was determined in singles, and with increasing litter size the birth weight of goat kids decreased. It was determined statistically significant effect (P <0.0001) of breed, sex, litter size and the order of kidding on the goat kids birth weight

PRKAG3 GENE POLYMORPHISMS AND PORK QUALITY

Česta pojava povećanog nakupljanja glikogena u mišićima i nizak konačni pH mesa kod svinja Hampshire pasmine i njezinih križanaca imaju genetsku osnovu. Uvjetuje ga dominantni mutirani RN¯ alel (R200Q supstitucija) na PRKAG3 genskom lokusu smještenom na 15. kromosomskom paru. PRKAG3 (¨Rendement Napoli¨ ili RN) gen kodira specifičnu izoformu γ3-pod-jedinice adenozin-monofosfat (AMP) aktivirane protein-kinaze (AMPK), ključnog enzima uključenog u regulaciji energetskog metabolizma stanice. Kod RN¯ mutanata je zbog visoke razine glikolitičkog supstrata (glukoze) u mišićima produljen pad pH post mortem, uz nisku konačnu pH–vrijednost mesa (tzv. ¨kiselo meso¨). Uz niski pH, ovakvo meso je svjetlije boje, reducirane sposobnosti vezanja vode, nižeg sadržaja proteina i općenito lošije preradbene kakvoće u odnosu na normalnu svinjetinu. Osim RN¯ mutacije, pronađeno je još nekoliko funkcionalno značajnih polimorfizama na PRKAG3 genu, od kojih je najvažniji rn* alel (V199I supstitucija), koji prevladava u većine komercijalnih pasmina, a na kakvoću mesa djeluje suprotno od RN¯ alela. Genski testovi za otkrivanje PRKAG3 polimorfizama danas su komercijalno dostupni, te ih uzgajivači svinja širom svijeta mogu koristiti u selekciji protiv RN¯ mutacije, ili kao pomoć u poboljšanju kakvoće mesa primjenom drugih molekularnih markera PRKAG3 gena.The frequent occurrence of glycogen hyper-accumulation and low ultimate pH in the meat of Hampshire pig breed and its crossbreeds has genetic background. It is caused by mutated dominant RN¯ allele on PRKAG3 (R200Q substitution) gene loci located at pig chromosome 15. PRKAG3 (also known as Rendement Napole or RN) gene encodes a specific γ3-subunit of adenosine monophosphate (AMP)-activated protein-kinase (AMPK), a key enzyme involved in regulation of energy metabolism of the cells. In RN¯ mutants, due to the high levels of glycolytic substrate (glucose) in muscles, the pH fall post mortem is extended with low ultimate pH of meat (¨acid meat¨). Beside the low pH, such a meat is paler in colour, with reduced water holding capacity, lower protein content and, generally has poorer processing quality compared with normal pork. In addition to RN¯ mutation in Hampshire populations, several other functionally significant polymorphisms of PRKAG3 has been determined, e.g., rn* allele (V199I substitution), which prevails in most commercial pig breeds and acts contrary to RN¯ on meat quality. Genetic test for PRKAG3 gene polymorphisms are now commercially available and pig breeders around the world may use them in selection against RN¯ mutation, or as a help to improve meat quality by using the other molecular markers of PRKAG3

Svojstva trupa i boja mesa janjadi iz različitih sustava proizvodnje.

Sheep production in Croatia is primarily based on indigenous breeds and different production systems determined by specific environmental conditions and tradition. The aim of this research was to determine the influence of sex on birth weight, daily gain, pH value, and meat colour as well as the slaughter and carcass traits of lambs derived from three different sheep production systems. For that purpose a total of 306 lambs from three breeds reared in three production systems with different production goals were randomly selected: I - milk production, Pag sheep (total 112 lambs: 66 males and 46 females); II - lamb meat production, Dalmatian Pramenka (total 96 lambs: 52 males and 44 females), and III - milk and lamb meat production, Istrian sheep (total 98 lambs: 54 males and 44 females). Sex only had a significant influence on daily gain and age (P<0.01), and weight at slaughter (P<0.05) in production system III. The effect of sex on slaughter characteristics between the investigated breeds was variable. The highest pH value of m. longissimus dorsi (MLD) was determined in production system III, while the L* value of the same muscle differed (P<0.001) between all three production systems and the b* value was significantly lower in production system II. The highest value of L* and b* parameters of m. rectus abdominis (MRA) was determined in production systems III and I, respectively. Sex significantly affected the b* parameter of MRA in production system I, L* parameters of MLD and MRA in production system II, and pH value and L* parameter of MLD in production system III. The results of this study indicate that in a rather small geographical area the possibilities exist for the production of lamb carcasses with specific quality characteristics.Ovčarska proizvodnja u Hrvatskoj primarno se temelji na izvornim pasminama i različitim sustavima proizvodnje te je određena tradicijom i specifičnim uvjetima okoliša. Cilj ovog istraživanja bio je utvrditi utjecaj spola na porođajnu masu, dnevni prirast, pH vrijednost i boju mesa kao i klaoničke pokazatelje te odliku trupova janjadi iz tri različita sustava ovčarske proizvodnje. Za tu svrhu nasumično je odabrano ukupno 306 janjadi triju pasmina uzgajane u tri različita proizvodna sustava: I. – proizvodnja mlijeka, paška ovca (ukupno 112 janjadi: 66 muške i 46 ženske); II. – proizvodnja janjećeg mesa, dalmatinska pramenka (ukupno 96 janjadi: 52 muške i 44 ženske) i III. – proizvodnja mlijeka i janjećeg mesa, istarska ovca (ukupno 98 janjadi: 54 muške i 44 ženske). Spol je značajno utjecao na dnevni prirast i dob (P<0,01) te tjelesnu masu prije klanja (P<0,05) samo u proizvodnom sustavu III. Utvrđen je varijabilan utjecaj spola na klaoničke pokazatelje janjadi istraživanih pasmina. Najviša pH vrijednost m. longissimus dorsi (MLD) utvrđena je u proizvodnom sustavu III namijenjenom proizvodnji mlijeka i mesa. L* vrijednost MLD-a razlikovala (P<0,001) se između sva tri proizvodna sustava, dok je b* vrijednost bila značajno niža u proizvodnom sustavu II. Najviša vrijednost L* pokazatelja m. rectus abdominis (MRA) utvrđena je u proizvodnom sustavu III, a najviša vrijednost b* pokazatelja MRA-a u proizvodnom sustavu I. Spol je značajno utjecao na b* pokazatelj MRA u janjadi paške ovce, L* pokazatelj MLD-a i MRA u janjadi dalmatinske pramenke te pH vrijednost i L* pokazatelj MLD-a u proizvodnom sustavu III. Rezultati ovog istraživanja sugeriraju da unutar malog zemljopisnog područja postoje mogućnosti za proizvodnju janjećih trupova sa specifičnim kvalitativnim karakteristikama