Effects Of Different Chain Langth Of Fatty Acids On Milk Fat Synthesis In Dairy Cows

Dietary supplements long chain fatty acids (LCFA) increased percentage of LCFA in dairy cows milk fat, whereas decreased percentage of short and medium chain fatty acids(SMCFA), their effect on milk fat percentage usually decreased while concomitant reduction in SMCFA largely than LCFA.The research aims to discussed and compared the contribution of milk fat synthesis between SMCFA and LCFA.Experiment 1 Analysed the physicochemical property and fatty acids of several non-esterified fatty acid or oil have different chain or saturated, the results showed the percentage of fatty acid in non-esterified fatty acid more than 98%. The major fatty acid in olive oil,soybean oil and linoleic acid was c-9C18:1(72.78%),c-9-c-12C18:2 (60.70%), c-9-c-12-c15C18:3(82.40%).44 degree palm oil have more percentage of C16:0 than 18 degree palm oil (51.00% vs.35.29%).Experiment 2 The research simulated the percentage of LCFA in milk fat of hostein cows to study the influence of milk fat synthesis.The treatments are control, 400g/d LCFA,400g/d butterfat. The research showed, compared with control, dietary added 400g/d LCFA have no significant different with DMI, milk yield, and milk component; added 400g/d LCFA increased C >16:0 concentration significantly, the percentage of c-9C18:1 increased 6.99%, but have no significant different, whereas C14:0 and C<16:0 concentration in milk significant decreased; the concentration of NEFA increased 13.63%, and significantly increased very low density lipoprotein. Compared with control, added 400g/d butterfat had no significant different between DMI, milk yield, milk fat percentage and other milk component.There are no significant different of rumen fermentation index between 3 treatments.Experiment 3 18-carbon fatty acid in milk was absorbed from blood directly by dairy cow mammary gland. Four major fatty acids of 18-carbon fatty acid (stearic acid,oleic acid,linoleic acid,linolenic acid) were stimulated from hostein dairy cows fatty acids and infused into duodenum(treatment1, stearic acid+oleic acid+linoleic acid+linolenic acid, 154 g/d+216 g/d +18 g/d +12 g/d), other treatment other treatment will removed linolenic acid(treatment2, stearic acid+oleic acid+linoleic acid, 154 g/d+216 g/d +18 g/d), linoleic acid(treatment3, stearic acid+oleic acid +linolenic acid, 154 g/d+216 g/d+12 g/d), oleic acid(treatment4, stearic acid +linoleic acid+linolenic acid, 154 g/d +18 g/d +12 g/d) and stearic acid(treatment5, oleic acid+linoleic acid+linolenic acid, 216 g/d +18 g/d +12 g/d). The result showed there is no significant different of DMI, milk yield, milk fat percentage and other milk component while the milk fat percentage lower than milk protein percentage between treatments; infused treatment 2 resulted the C18:3 concentration in blood significant decreased, infused treatment 4 resulted C18:1 concentration decreased 46%, C18:3 and PUFA concentration increased significant, treatment 3 and treatment 5 have no significant different of C18:2 and C18:0 and other fatty acids; there were no significant different of blood physiology and biochemistry index between treatments.Experiment 4 There are two sources of fatty acids from dietary into mammary gland, the research was compared the contribution of mammary gland of two sources fatty acids, butterfat was used into treatment to be middle. Treatment are 400g/d SMCFA,400g/d butterfat and 400g/d LCFA. The results showed, as SMCFA level increased and LCFA level decreased, milk fat percentage increased quadratic.400g/d SMCFA had increased significant compared with 400g/d LCFA, there are no significant between DMI, milk yield, other component of milk; concentration of C10:0,C12:0,C14:0,C16:0,TSFA,C<16:0 in milk fat significant increased linear or quadratic as SMCFA level increased,LCFA level decreased, SMCFA significant higher than LCFA, C18:0,c-9-C18:1,c-9-c-12-C18:2,CLA,TMUFA,TPUFA,C>16:0 in milk fat significant decreased linear or quadratic as SMCFA level increased,LCFA level decreased, SMCFA significant lower than LCFA; concentration of C14:0 significant higher when SMCFA compared with LCFA; there was no significant different in rumen fermentation indexs between SMCFA compared with LCFA. the results showed that, SMCFA had more contribution than LCFA in milk fat synthesis in mammary gland, The fatty acids in milk and blood had respectively change along with the level of SMCFA and LCFA.