Effects Of Dietary Linoleic Acid And Vitamin A On Stearoyl-CoA Desaturase In Mammary Gland And Muscle

Experiments were conducted to investigate the effects of 1)dietary lionleic acid (LA) on gene expression and activity of stearoyl-CoA desaturase (SCD) in mammary gland of lactating goat ;and 2)dietary vitamin A (VA) on SCD activity of longissimus dorsi muscle in crossbred beef cattle.In experiment 1, twelve Xinong Sanen goats (days in milk averaged 36±3) were randomly assigined to two groups (n=6) with a complete randomized design design. Treatments consisted of a 0 or 40g/kgDM LA supplement.On day 28 ,mammary gland biopsies were performed by surgery and a protion of the tissue analyzed for mRNA expression of SCD by real time PCR. The activity of SCD was evaluated with another portion of the tissue.Compared to control group(0 supplement of LA), goats fed 40g/kgDM of dietary LA decreased the SCD gene expression in mammary gland (P<0.05) . The SCD activity did not differ significantly between 0 or 40g/kgDM of dietary LA supplement (P>0.05 ) .However,it showed a numerical decrease of SCD activity in 40g/kgDM of dietary LA supplement.In experiment 2, LimousinxLuxi crossbred beef cattles(n=32, 12mth old) with a average body weight of 350±5 kg were randomly allocated to one of four groups. Catties in four treatments were fed diets containg 0, 50%, 100% and 200% of the 2200 IU/kgDM basal dietary VA, respectively. All catties were weighted monthly and 3 catties within each goup were slauthered after 3 months feeding, longissimus dorsi muscle samples were taken for determination of the SCD activity. The rest catties were not slautered until 6 month of feeding. During the 3 month feeding, the SCD activity was higher in VA supplement groups than the control group(p<0.05),while did not differ among 50%, 100% and 200% supplement groups(p>0.05). However, the SCD activity in muscles of catties of 6 month feeding decreased as dietary VA increasing in 100% and 200% groups.In conclusion, lactating goats fed with 40g/kgDM LA decreased Mrna expression and activity of SCD in mammary gland. The appropriate dose of VA could increase SCD activity of longissimus dorsi muscle in a short period.