217 Young Scholar Presentation: The use of diverse cattle breeds to understand marbling development and growth

Abstract

Abstract Wagyu cattle have been genetically selected to have superior marbling deposition compared with many other cattle breeds, including Angus. It was hypothesized that greater marbling deposition by Wagyu influenced cattle may be due to an additional wave of adipogenic gene expression compared with Angus cattle. The present study compared the expression of lipid metabolism genes within the longissimus muscle (LM) of Wagyu and Angus sired cattle at similar harvest endpoints: days on feed and age, or body weight (613 kg). Angus sired steers were sired by an Angus bull selected for marbling (T1), while Wagyu sired steers were sired by either a Wagyu bull selected for growth (T2 & T4) or marbling (T3 & T5), at the respective age or body weight endpoints. Cattle were weaned at 7 months of age, entered the feedlot 54 d later, and consumed the same growing (119 d) and finishing ration. Muscle biopsies were collected from the LM posterior to the 13th rib at approximately 7, 9, 11, 14, and 17 months of age (harvest) for T1, T2, and T3 cattle. Muscle biopsies for T4 and T5 cattle were collected when their body weight was similar to T1 cattle at the time of biopsy, approximately 241, 276, 400, 531, and 613 kg (harvest). The high marbling sired Wagyu steers (T3 &T5) had greater marbling scores and percent LM lipid compared with high growth Wagyu (T2 & T4) and Angus sired steers. Gene expression results from high marbling sired Wagyu steers (T3 &T5) demonstrated additional peaks of PPARδ mRNA expression, greater and earlier PPARγ mRNA expression, and greater or additional peaks of GPAM1, LPIN1, and HSL mRNA expression compared with high growth Wagyu (T2 & T4) and Angus sired steers.