Effects of supplements differing in fatty acid profile to late gestational beef cows on cow performance,calf growth performance,and mRNA expression of genes associated with myogenesis and adipogenesis

Background:Maternal nutrition during gestation affects fetal development,which has long-term programming effects on offspring postnatal growth performance.With a critical role in protein and lipid metabolism,essential fatty acids can influence the development of muscle and adipose tissue.The experiment investigated the effects of late gestation supplements(77 d prepartum),either rich in saturated and monounsaturated fatty acids(CON;155 g/cow/d EnerGII)or polyunsaturated fatty acids(PUFA;80 g/cow/d Strata and 80 g/cow/d Prequel),on cow performance and subsequent calf growth performance as well as mRNA expression in longissimus muscle(LM)and subcutaneous adipose tissue at birth and weaning.Results:There was no difference(P≥0.34)in cow body weight(BW)or body condition score from presupplementation through weaning.Relative concentrations of C18:3n-3 and C20:4n-6 decreased(P≤0.05)to a greater extent from mid-supplementation to calving for PUFA compared with CON cows.Cow plasma C20:0,C20:5n-3,and C22:6n-3 were increased(P≤0.01)in PUFA during supplementation period.At birth,PUFA steers had greater(P=0.01)plasma C20:5n-3.No differences(P≥0.33)were detected in steer birth BW or dam milk production,however,CON steers tended(P=0.06)to have greater pre-weaning average daily gain and had greater(P=0.05)weaning BW compared with PUFA.For mRNA expression in steers:MYH7 and C/EBPβin LM increased(P≤0.04)to a greater extent from birth to weaning for PUFA compared with CON;MYF5 in LM and C/EBPβin adipose tissue tended(P≤0.08)to decrease more from birth to weaning for CON compared with PUFA;SCD in PUFA adipose tissue tended(P=0.08)to decrease to a greater extent from birth to weaning than CON.In addition,maternal PUFA supplementation tended(P=0.08)to decrease MYOG mRNA expression in LM and decreased(P=0.02)ZFP423 in adipose tissue during the pre-weaning stage.Conclusions:Late gestation PUFA supplementation decreased pre-weaning growth performance of the subsequent steer progeny compared with CON supplementation,which could have been a result of downregulated mRNA expression of myogenic genes during pre-weaning period.