Effect of whole linseed and rumen-protected conjugated linoleic acid enriched diets on feedlot performance, carcass characteristics, and adipose tissue development in young Holstein bulls

Forty-eight young Holstein bulls (slaughtered at 458.6 ± 9.79 kg body weight) were used to evaluate the effect of whole linseed and conjugated linoleic acid (CLA) supplementation on animal performance, adipose tissue development, and carcass characteristics. The animals were fed with one of four isoenergetic and isoproteic diets: control (0% linseed, 0% CLA), linseed (10% linseed, 0% CLA), CLA (0% linseed, 2% CLA), and linseed plus CLA (10% linseed, 2% CLA). Animal performance and carcass characteristics were unaffected by diet composition. Adding linseed or CLA to the concentrate diet did not result in significant differences in adipocyte size and number or lipogenic enzyme activity. However, while the frequency distribution of subcutaneous adipocyte diameters followed a normal distribution, the frequency distribution of intramuscular adipocyte diameters was not normal in any dietary group (skewness coefficients: 0.8, 1.2, 0.9, 0.8 for control, linseed, CLA, and linseed plus CLA, respectively; P < 0.05), indicative of adipocyte proliferation in the intramuscular adipose tissue.

► Isoenergetic diets with CLA and/or linseed were tested for fattening young bulls. ► Carcass characteristics were unaffected by diet. ► The intramuscular adipocyte diameter distribution was indicative of hyperplasia. ► Adipose enzyme activity was not influenced by CLA or linseed diets. ► Similar adipose enzyme activity gave rise to similar meat marbling.