-The single and combined effects of polymorphism in the 5'-noncoding region of the bovine growth hormone receptor (GHR) gene was examined on the traits related to feed intake and meat production in beef cattle. Four different single nucleotide polymorphisms (SNP) were analysed. Seventy-one young bulls belonging to four beef breeds (Charolais, Limousin, Aberdeen Angus, Hereford) and one dual purpose breed (Simmental) were included in the study. The traits analysed were daily weight gain, feed intake and conversion, and carcass parameters. The results showed that genetic variants at the 5'-noncoding region of the bovine GHR gene had a marked effect on beef production traits. The (-) allele at the polymorphic AluI site appeared favourable for weight of carcass and percentage of valuable cuts. The animals with the +/+ genotype for the RFLP-AccI polymorphism seemed better for the percent of lean in valuable cuts, while those with the +/+ genotype at the polymorphic Fnu4HI site appeared superior for daily gain and feed conversion during the feed test period. A higher percent of lean in valuable cuts was shown for the bulls of the -/-genotypes at the NsiI site. In addition, statistically significant associations were shown between combined GHR genotypes and feed consumption, carcass weight and dimensions.growth hormone receptor / gene polymorphism / cattle / meat production traits Résumé -Polymorphisme dans la région 5' non codante du gène du récepteur de l'hormone de croissance associé aux caractères de production de viande chez les bovins. L'effet du polymorphisme dans la région 5' non codante du gène du récepteur de l'hormone de croissance bovine (GHR) sur les caractères associés à la consommation de fourrage et à la production de viande chez les bovins de boucherie a été examiné. Quatre polymorphismes nucléotidiques simples (SNP ; single nucleotide polymorphisms) différents ont été analysés. Soixante et onze jeunes taureaux appartenant à 4 races bovines à viande (Charolaise, Limousine, Aberdeen Angus, Hereford) et une race bovine mixte (Simmental) ont été inclus dans l'étude. Les caractéristiques suivantes ont été analysées: gain moyen quotidien, consommation de fourrage, indice de consommation et qualité de la carcasse. Les résultats montrent que les variants génétiques pour la région 5' non codante du gène

ABSTRACT:The effect of the insulin-like growth factor 2 (IGF2) gene polymorphism -a g.292C>T transition in exon 2 on feed uptake and conversion, growth rates, and meat production traits in Polish HolsteinFriesian cattle was investigated. A total of 291 young bulls were genotyped using restriction fragment length polymorphism (RFLP-BsrI). Animals were slaughtered at the age of 11 or 15 months and carcass traits were examined. At the age of 11 months the association was shown of the CC genotype with higher cold carcass weight, daily gain and meat content (%) in valuable cuts. At 15 months of age the CC genotype bulls showed higher live body weight, whereas those with the CT genotype had more fat in valuable cuts. The TT genotype bulls appeared to consume more feed (dry matter and protein) and used more feed for maintenance and meat production as compared to the CC genotype. The imprinting status of the IGF2 gene was analysed using cDNA sequencing and RFLP-BsrI. In 15-months-old animals and in foetuses older than two months both IGF2 alleles, maternal and paternal, were equally expressed in liver. In a 2-months-old male foetus the IGF2 mRNA was primarily expressed from the paternal allele.

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The experiment was performed on 30 Black-and-White Lowland calves of 87.0-90.3 kg body weight. The animals were divided into three groups fed meadow hay and a control granulated concentrate -C, supplemented with 2.5% betaine -B (Betafin -Finnsugar Bioproducts, Helsinki, Finland) or with 2.25% choline chloride -CH (Prince Agri Products, Inc., Quincy, II, USA), which was equivalent to about 0.5% of the rumen undegradable choline.The daily body gain of animals fed the C diet and the B diet was the same, 0.849± 0.029 kg, but in calves of the CH group was 0.898 ± 0.029 kg. The concentrate efficiency ratio was 3.06 ± 0.097, 3.13 ± 0.097 and 2.91 ± 0.097 kg in the C, B and CH group, respectively. The relative growth rate was higher (P< 0.10) in the CH group, reaching 131.7 ± 1.40, 169.1 ±2. 71 and 210.6 ± 4.84% of the initial weight in the 5 th , 10 th and 15 th weeks, respectively. The results achieved suggest that 0.5% rumen undegradable choline has a positive effect on production performance of half year old calves. In contrast, 2.5% betaine supplementation had no effect on production performance even though it was administered at 5-times higher levels than the rumen undegradable choline.

Acyl-CoA:diacylglycerol acyltransferase-1 (DGAT-1) is a key enzyme involved in triglyceride synthesis. DGAT-1 gene is located in the centromeric region of the bovine chromosome (BTA) 14 and considered polymorphism was identified as a candidate gene for milk and meat QTL. One of mutations which is substitution AA → GC in exon 8 causes an amino acid change in the product. The effect of the lysine/alanine (K232A) diallelic polymorphism on meat production traits has been studied. 156 young Black-and-White (Friesian) bulls were genotyped. The association between diacylglycerol acyltransferase polymorphism and slaughter performance and meat technology analysis were examined. Moreover the fatty acid profile (C12-C20:5) including CLA in the sample of longissimus dorsi (LD) muscle was evaluated. Differences (P ≤ 0,05) were found between genotypes in slaughtering performance traits as well as fat and valuable cuts content and meat-fat ratio. The significant difference occurred also in the water holding capacity. Heterozygous individuals AA:GC were characterized by the greatest values compared with homozygous ones. Bulls of DGAT-1 genotype GC:GC showed significantly higher (P ≤ 0,05) content of lauric acid in LD muscle and heterozygous animals differ in CLA content with homozygous AA:AA.