Effects of a Strategic Supplementation in the Deposition of Intramuscular and Subcutaneous Fat of Young Bulls, on a Grass Fed System Based on Tropical Grasses in Puerto Rico

The effect of a strategic supplementation (protein/energy) in the % of intramuscular fat, total trimmed fat, and subcutaneous fat thickness was determined. Weaned calves (9 months; n=48) were distributed in 3 treatments: T1 = grazing only; T2 = T1 + wheat meadlings (0.35-0.55% live weight). T3 = T1 + wheat meadlings (0.35-1.1 % live weight) + fattening ration 60 days before slaughter. Animals were slaughtered (487 Kg.; 20 months) and % of intramuscular fat, total trimmed fat, and subcutaneous fat thickness were determined. Supplementation increased the % of intramuscular fat in the muscles Longissimus dorsi (LD), Semimembranosus (SM), and Semitendinosus (ST) (P = 0.0495), and there was no interaction between treatment and muscle (P = 0.95). Only T1 was statistically diferent from T3 (P = 0.039). Treatments tended to increase total trimmed fat (P = 0.084), but there was no treatment effect of subcutaneous fat thickness (P = 0.32). Strategic supplementation increased the percentage of intramuscular fat in young bulls grazing tropical grasses without significantly increasing subcutaneous back fat.

Key words: Marbling, Strategic suplementation, Beef, Subcutaneous fat, Trimmed fat, Bovines