Effects Of Dietary Supplementation Of Oilseeds On Lipid Metabolism And Fatty Acid Composition In Sheep

Four experiments were conducted to evaluate the effects of dietary supplementation of canola seeds,sunflower seeds,and flaxseeds on the growth performance,rumen fermentation characteristics,lipid metabolism and fatty acid composition of fattening sheep.Forty crossbreed male lambs(Han sheepxMongolian sheep)with initial body weight about 33.7 kg were individually penned and used in a complete randomized design with 4 treatments by 10 animals per group.Dietary treatments were control diet with no oilseeds,but soybean and cottonseed meal in stead;treatment diets were formulated by adding 10%of canola seeds,sunflower seeds,and flaxseeds,respectively in substitution of soybean and cottonseed meal.The animals were allowed 10 days to adapt to the diets and data were collected in the following 35 days.Animals had free access to clean water throughout the study.Experiment 1:Effects of dietary supplementation of oilseeds with different fatty acid profiles on the growth performance,carcass characteristics and rumen fermentation characteristics in fattening sheep.Within the 45d of experimental period,the amount of diets offered and refused was recorded daily and lambs were weighted every 10 days to record the growth performance,then all animals were slaughtered for carcass characteristics evaluations at the end of the feeding trial.The results showed that,there was no difference in growth performance(P>0.05).Compared to animals in control diet,animals receiving treatment diets were lower in average daily gain(ADG)and dry matter intake(DMI),but not significant(P>0.05).Rumen PH was significantly(P<0.01)higher in animals fed flaxseed and lower in canola seeds group than those in animals fed sunflower seed and control diet.Rumen concentrations of NH3-N was significantly(P<0.05)increase in flaxseed group.But rumen BCP were not significantly influenced by the treatments(P>0.05).In summary,the treatments in this study had no significant effects on the growth performance of fattening sheep,flaxseed had a influence on rumen fermentation characteristics,but in normal range.Results from this experiment suggested that further modification of fatty acid profiles to produce functional mutton is possible by oilseed supplementation.Experiment 2:Effects of dietary supplementation of oilseeds with different fatty acid profiles on lipid metabolism in fattening sheep.At the end of the feeding trial,the lambs were blooded for serum lipid profile.The results showed:there was no difference in TG(P>0.05);Compared to the control diet,the CHOL、HDL-C and LDL-C were significantly(P<0.05)increased in sunflower seed diet,so,addition of sunflower seed to diet could enhance the adipose deposit of body.Experiment 3:Effects of dietary supplementation of oilseeds with different fatty acid profiles on fatty acid composition in fattening sheep.After all animals were slaughtered,subcutaneous adipose were collected for fatty acid composition.The results showed:adipose tissues from animals fed sunflower and flaxseed diets had significantly higher concentrations of PUFA(P<0.05)when compared to those from animals fed other diets.Animals receiving canola diet contain higher PUFA in adipose tissue in contrast to animals receiving control diet,but not significant(P>0.05).Adipose concentrations of unsaturated fatty acids(USFA)were higher in animals fed canola and sunflower seeds than those of animals fed control and flaxseed diets(P<0.05).Compared to control diet,treatment diets significantly reduced adipose concentrations of saturated fatty acids(P<0.05).As to the ratio of n-6 to n-3 PUFA in adipose tissue of animals fed treatment diets,we found the following sequence:flaxseeds diet(4.49)<canola diet(8.77)<control diet(13.92)<sunflower diet(17.40).The data in this study indicate that feeding animals canola and sunflower seeds significantly increased adipose concentrations of unsaturated fatty acids,and feeding animals flaxseeds significantly increased adipose concentrations of n-3 and PUFA in fattening sheep.In conclusion,dietary supplementation of canola seeds,sunflower seeds and flaxseeds can increase tissue concentrations of functional fatty acids such as omega-3 and PUFA with no significant effects on rumen fermentation and growth performance.