This review summarises the known effects of dietary factors on bovine and caprine milk fatty acid composition, as well as the regulation of cow and goat mammary lipid secretion. Special attention is given to fatty acids that could play a role for human health, such as saturated fatty acids, oleic acid, n-6- or n-3-C18 to C22 polyunsaturated fatty acids, trans isomers of C18:1 and C18:2, and isomers of conjugated linoleic acid (CLA). The main dietary factors taken into account are the nature of forages, including pasture, the forage:concentrate ratio and diet starch content, and the supplementation of dairy rations with crude or processed vegetable oils or oilseeds, and vitamin E. A particular emphasis is given to studies on interactions between these dietary factors, which show that there is a considerable plasticity of ruminant milk fatty acid composition. Despite the existence of several studies on the effects of dietary factors on the sensorial quality of milk and dairy products, there is a need to evaluate more deeply how the different feeding strategies could change the nutritional, sensorial and technological aspects of milk fat quality. dairy cow / dairy goat / forages / oilseeds / milk / fatty acids / human health

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Dietary lipids and forages interactions on cow and goat milk fatty acid composition and sensory properties

Molecular dissection of a quantitative trait locus: a phenylalanine-to-tyrosine substitution in the transmembrane domain of the bovine growth hormone receptor is associated with a major effect on milk yield and composition.

Genes that regulate metabolism and energy partitioning have the potential to influence economically important traits in farm animals, as do polymorphisms within these genes. In the current study, SNP in the bovine neuropeptide Y (NPY), growth hormone receptor (GHR), ghrelin (GHRL), uncoupling proteins 2 and 3 (UCP2 and UCP3), IGF2, corticotrophin-releasing hormone (CRH), cocaine and amphetamine regulated transcript (CART), melanocortin-4 receptor (MC4R), proopiomelanocortin (POMC), and GH genes were evaluated for associations with growth, feed efficiency, and carcass merit in beef steers. In total, 24 SNP were evaluated for associations with these traits and haplotypes were constructed within each gene when 2 or more SNP showed significant associations. An A/G SNP located in intron 4 of the GHR gene had the largest effects on BW of the animals (dominance effect P < 0.01) and feed efficiency (allele substitution effect P < 0.05). Another A/G SNP located in the promoter region of GHR had similar effects but the haplotypes of these 2 SNP reduced the effects of the SNP located in intron 4. Three SNP in the NPY gene showed associations to marbling (P < 0.001) as well as with ADG, BW, and feed conversion ratio (FCR; P < 0.05). The combination of these 3 SNP into haplotypes generally improved the association or had a similar scale of association as each single SNP. Only 1 SNP in UCP3, an A/G SNP in intron 3, was associated with ADG (P = 0.025), partial efficiency of growth, and FCR (P < 0.01). Three SNP in UCP2 gene were in almost complete linkage disequilibrium and showed associations with lean meat yield, yield grade, DMI, and BW (P < 0.05). Haplotypes between the SNP in UCP3 and UCP2 generally reduced the associations seen individually in each SNP. An A/G SNP in the GHRL gene tended to show effects on residual feed intake, FCR, and partial efficiency of growth (P < 0.10). The IGF2 SNP most strongly affected LM area (P < 0.01), back fat, ADG, and FCR (P < 0.05). The SNP in the CART, MC4R, POMC, GH, and CRH genes did not show associations at P < 0.05 with any of the traits. Although most of the SNP that showed associations do not cause amino acid changes, these SNP could be linked to other yet to be detected causative mutations or nearby QTL. It will be very important to verify these results in other cattle populations.

Polymorphisms and haplotypes in the bovine neuropeptide Y, growth hormone receptor, ghrelin, insulin-like growth factor 2, and uncoupling proteins 2 and 3 genes and their associations with measures of growth, performance, feed efficiency, and carcass merit in beef cattle.

Leptin is the hormone product of the obese gene synthesized and secreted predominantly by white adipocytes. It functions as a lipostatic signal regulating BW, food intake, energy expenditure, reproduction, and certain immune system functions. Although previous studies have identified polymorphisms in the coding regions of the leptin gene in cattle that show considerable associations with feed intake, milk quality and quantity, and carcass fatness, no such associations have been reported for the leptin promoter. The current study reports associations between SNP in the 5' untranslated promoter region of the bovine leptin gene with serum leptin concentration, growth, BW, feed intake, feeding behavior, and carcass merit in hybrid cattle (n = 150). The study showed that animals with the TT genotype of a less frequent cytosine/thymine (C/ T) substitution (UASMS2; frequency of thymine allele equals 0.21) detected at position 528 in the bovine leptin promoter (GenBank Accession No. AB070368) show 48 and 39% increases in serum leptin concentration (P < 0.001), 39 and 31% increases in backfat thickness (P < 0.001), and 13 and 9% increase in marbling score (P = 0.01), compared with CC or CT genotypes, respectively. Animals with the TT genotype also show significantly higher feed intake (P < 0.001), growth rate, metabolic BW (P < 0.05), and live weight at slaughter (P < 0.10). Animals with the GG genotype of a more frequent cytosine/guanine (C/G) substitution (UASMS3; frequency of G allele equals 0.59) at position 1759 in the bovine leptin promoter (GenBank Accession No. AB070368) also show higher feed intake (P = 0.001), growth rate (P < 0.10), and BW (P < 0.01). The thymine allele of UASMS2 and the guanine allele of UASMS3 were separately associated with higher feeding duration (P < 0.05). The two SNP show significant linkage disequilibrium and could also be relevant in predicting other characteristics, such as milk yield and quality in cattle. These results, however, represent the initial associations of the polymorphisms with these traits, and further efforts are required to validate these findings in other populations.

Polymorphisms in the bovine leptin promoter associated with serum leptin concentration, growth, feed intake, feeding behavior, and measures of carcass merit.

Candidate growth genes in finfish — Where should we be looking?

Associations were studied between IGF-1 gene polymorphism and selected beef and milk production traits in Polish Holstein-Friesian (HF) cattle. The IGF-1 genotype was determined in a total of 662 HF cows, heifers and bulls. In month 8 of life, on 213 young animals of both sexes the 28-days feed intake and conversion test was conducted. Moreover, growth rate and beef production traits were determined on 131 HF bulls slaughtered at the age of 15 months. Referring to IGF-1 genotype also milk production traits were studied using performance data of 262 HF cows. Significant differences were found between IGF-1 genotypes in feed intake and feed conversion for growth. Animals carrying genotype BB consumed less dry matter, crude protein and energy per 1 kg body live weight gain than those of AA and AB genotypes. Moreover, the BB genotype appeared favourable for live weight gain during the test. The AB genotype was found positively associated with live body weight at slaughter, cold carcass weight, as well as weight of meat and fat in valuable cuts. Cows carrying AB genotype yielded daily more FCM and VCM milk and more milk fat and milk protein than those of AA and BB genotypes.

Effect of polymorphism in IGF-1 gene on production traits in Polish Holstein-Friesian cattle.

The association was studied between the polymorphism at leptin (LEP), Pit1, and STAT5A loci and meat production traits in 145 Black-and-White growing/fattening bulls. Genotypes of LEP, Pit1 and STAT5A were determined with the PCR-RFLP technique. Over the 8th month of age the 28-day performance test was introduced to assess growth rate and feed conversion during which the fullconcentrate diet was offered ad libitum. At the age of 15 months the bulls were slaughtered, and their carcasses cut and dissected into lean, fat and bone. The allele frequencies were 0.85, 0.07, and 0.08 for A, B and C LEP variants, 0.25 and 0.75 for A and B Pit1 variants, and 0.90 and 0.10 for C and T STAT5A variants, respectively. Polymorphism of leptin significantly affected some carcass traits, and among them the weight of carcass-side that was highest in the AA homozygotes. The effect of Pit1 genotype was observed on carcass dimensions only. The AA homozygotes had higher chest circumference, chest depth, and circumference of round, but BB homozygotes had a higher round width. CT genotype of the STAT5A-encoding gene significantly af fected four out of 36 carcass traits measured and was related to higher weight of bone of best + fore ribs (4.2 vs 3.8 kg) and of sirloin (1.6 vs 1.3 kg) as well as to oblique carcass length (140.5 vs 138.5 cm). The CC STAT5A genotype was associated with significantly higher live weight gain from 8 to 15 months (1.04 vs 0,97 kg daily).

Polymorphisms at loci of leptin (LEP), Pit1 and STAT5A and their association with growth, feed conversion and carcass quality in Black-and-White bulls

Alternative for modifying the fatty acid composition and decreasing the cholesterol level in the milk of cows

Polymorphisme dans la region 5' non codante du gene du recepteur de l'hormone de croissance associe aux caracteres de production de viande chez les bovins. L'effet du polymorphisme dans la region 5' non codante du gene du recepteur de l'hormone de croissance bovine (GHR) sur les caracteres associes a la consommation de fourrage et a la production de viande chez les bovins de boucherie a ete examine. Quatre polymorphismes nucleotidiques simples (SNP; single nucleotide polymorphisms) differents ont ete analyses. Soixante et onze jeunes taureaux appartenant a 4 races bovines a viande (Charolaise, Limousine, Aberdeen Angus, Hereford) et une race bovine mixte (Simmental) ont ete inclus dans l'etude. Les caracteristiques suivantes ont ete analysees: gain moyen quotidien, consommation de fourrage, indice de consommation et qualite de la carcasse. Les resultats montrent que les variants genetiques pour la region 5' non codante du gene du GRH ont un effet significatif sur la production de viande de boeuf. L'allele (-) dans le site polymorphe AluI semble favorable au poids de la carcasse et a la teneur en morceaux nobles. Les animaux possedant le genotype +/+ pour le polymorphisme RFLP-AccI tendent a ameliorer leur teneur en muscle dans les morceaux nobles, tandis que les animaux possedant le genotype +/+ dans le site polymorphique Fnu4HI ont ameliore la vitesse de croissance et l'indice de consommation. Pour la teneur en muscle dans les morceaux nobles, la meilleure performance a ete observee chez les taureaux possedant le genotype -/- dans le site NsiI. De plus, les genotypes combines du gene du GHR ont eu des effets significatifs sur la consommation de fourrage, le poids et les dimensions de la carcasse.

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Polymorphism in the 5’‑noncoding region of the bovine growth hormone receptor gene and its association with meat production traits in cattle

The calpain system originally comprised molecules: two Ca2+-dependent proteases, mu-calpain and m-calpain, and a third polypeptide, calpastatin, whose only known function is to inhibit the two calpains. This proteolytic system plays a key role in the tenderisation process that occurs during post-mortem storage of meat under refrigerated conditioning. Their polymorphism is examined from the point of view of their effect on corresponding production traits. The calpain genes are investigated as potential candidate genes for a quantitative trait locus (QTL) affecting meat tenderness. In this study a new single nucleotide polymorphism (SNP) was found within intron 14 of the bovine CAPN1 gene, being transition C --> T at position 4685 nt (consensus sequence - GenBank No. AF 248054), as this mutation creates a new FokI restriction site detected with PCR-RFLP analysis. This sequence fragment of the SNP position has already been deposited in the GenBank database under accession No. AY639597. The RFLP-FokI polymorphism was studied in 141 bulls of seven breeds, including the native Polish Red (PR, preserved), and Polish Black-and White (BW) breed. The frequency of alleles T and C varied between the breeds considered, the mean reaching 0.38 and 0.62, respectively. Associations between CAPN1/FokI gene polymorphism and meat production traits were studied in BW (n = 84) young bulls. In the animals of the TT genotype the lean share in valuable cuts (%) was found more favourable than in CC animals.

J. Oprzadek

Papers

Effect of polymorphism in IGF-1 gene on production traits in Polish Holstein-Friesian cattle.

Polymorphisms at loci of leptin (LEP), Pit1 and STAT5A and their association with growth, feed conversion and carcass quality in Black-and-White bulls

Alternative for modifying the fatty acid composition and decreasing the cholesterol level in the milk of cows

Polymorphism in the 5’‑noncoding region of the bovine growth hormone receptor gene and its association with meat production traits in cattle

Bovine mu-calpain (CAPN1) gene: new SNP within intron 14.