Effects of diet and genotype at CSN1S1 locus on the oxidative stress in lactating goats

Twenty-eight Girgentana goats were selected on the basis of theirCSN1S1 genotype as follows: 14 goats homozygous for strong (AA)alleles and 14 goats heterozygous (AF). The goats were used in a2 x 4 factorial arrangement of treatments, with the two genotypes(G) and four diets (D). The diets were: a pelleted alfalfa hay(100H), a complete feed including alfalfa hay at 65% (65H), freshsulla (Hedysarum coronarium L.) forage (100S) and fresh sullaplus barley (65S). Each trial consisted of 15d for adaptation and 8dfor sample collection, during which the goats received the scheduleddiet ad libitum. Blood samples were collected at the end ofpre-experimental and experimental period. Plasma content ofReactive Oxygen Metabolites (ROMs), biological antioxidantpotential (BAP) and -tocopherol were measured by colorimetricassay and HPLC, respectively. Data were analysed by ANOVAincluding effect of G, D and interaction G x D. There was no significanteffect of G and interaction G x D on all parameters. Dietsignificantly influenced ROMs, BAP and -tocopherol. The ROMsconcentration was significantly lower (P<0.05) in goats thatreceived fresh forage 100S and 65S (4.20 and 4.53 lnUCarr) comparedto goat groups that received hay 100H and 65H (5.24 and5.20 lnUCarr). The BAP was higher (P<0.05) in 100S, 65S and 65H(respectively 8.01, 7.99 and 7.95 lnEq/L) than in 100H (7.66lnEq/L). Plasma -tocopherol was significantly higher in 100Sand 65S diets compared with 100H and 65H diets (respectively2.36 and 2.17 vs 1.79 and 1.81 ln mol/L; P<0.03). A negative correlationbetween ROMs and -tocopherol concentration wasobserved (r=-0.80; P<0.05). On the contrary, positive correlationsbetween -tocopherol and BAP plasma content (r=0.31; P<0.02)and milk production (r=0.28; P<0.03) were found. This study hasidentified that diet (fresh forage vs dry diet) rather than genotypehas a more pronounced effect on oxidative stress.