ASSOCIATION BETWEEN THE POLYMORPHISM AT CASEIN LOCI AND MILK FATTY ACID COMPOSITION IN GIRGENTANA GOATS

composition is an important trait for the goat dairy industry because of its influence on cheese yield and the organoleptic properties of dairy products (Chilliard et al., 2003). Goat milk is particularly rich in saturated fatty acids (SFA) whereas monounsaturated (MUFA) and polyunsaturated (PUFA) FA are less abundant (Fontecha et al., 2000).The aim of this work was to provide new data to better understand the influence of polymorphism at casein loci on fatty acid profile in Girgentana goat milk. One hundred lactating Girgentana goats, homogeneous for milk production, days of lactation, body weight and diet were used. The procedure was developed using individual raw milk samples, collected in three different stages of lactation: (October, February and June) from individuals with known genotypes at casein loci. Were analyzed animals with A*A*, B*B*, A*B*, FF, A*F, B*F, A*E, EF, FN, NN and A*N genotypes (where A* indicates A, G, I, and H alleles while B* indicates B1, B2, B3, B4 and C alleles) at αs1‐casein; CC, AC, A0', AC', C0', CC', and C'C' genotypes at β‐casein; AA, AC, AF, CF, EF and FF genotypes at αs2‐casein; and AA, AB, AD, AN, BB, BD, BN, DD and D'G genotypes at κ‐casein. Milk samples were prepared following the Rose‐Gottlieb’s method (1996) for FA extraction. For transesterification of the lipids KOH in methanol 2 N was used and thereafter the fatty acid methyl esters (FAMEs) were analyzed with a chromatographic method (Sağdiç et al., 2003).The determination of the fatty acid profile was performed by gas chromatography SHIMADZU GC‐2010 with flame ionization detector (GC‐FID). The FAMEs were injected into a capillary column (Zebron ZB‐WAX Plus 30m x 0:32 mm id, 0.2 mM film), identified according to the retention times and quantified by calibration curves. The results of fatty acid were expressed as g/100g total fat.Data set was analyzed using GLM procedures for repeated measure of SAS System v9.2. For almost all the fatty acid the environmental factors flock and month of sampling showed statistically significant differences. Among all the fatty acids investigated only two showed statistically significant differences between genotypes for κ‐casein, in particular C18 (stearic acid) and C18:01 (oleic acid). For αs1‐ , αs2‐ and β‐casein were not found statistically significant differences. The results showed that genetic polymorphisms at casein genes, in particular at κ‐casein, have important effects on goat milk fat and FA composition, especially for MUFA and PUFA, which are potentially involved as positive factors in the health of human consumers.