Chemical Composition, Color and Tenderness of Beef from Nellore and Nellore X Angus Steers Fed Whole Shelled Corn Diets

The objective was to evaluate quality of beef from Nellore and Nellore x Angus steers fed whole shelled corn (WSC) diets. Thirty-two steers with average body weight of 353 kg were used in a completely randomized design using a 2 x 2 factorial arrangement (2 breeds and 2 diets). One diet containing 80% WSC and 20% of a commercial pellet based on soybean meal and minerals (15.1% CP and 2.84 Mcal/kg). The other diet had 74% WSC, 20% of the same proteic-mineral pellet and 6% of sugarcane bagasse (14.7% CP and 2.75 Mcal/kg). Feeding period was 116 d, steers were fed individually and final BW was 431 and 463 kg for Nellore and crossbred steers (P<0.05), respectively. Twenty-four hours after slaughter, samples were taken from the LM muscle of the left half carcass between 12nd and 13rd ribs for chemical composition analysis, color (L*, a*, b*), cooking loss (CL) and shear force (SF). Statistical model included the effects of breed, diet, time and their interactions. There was no effect (P>0.05) of breed and diet on chemical composition, with mean values for moisture, crude protein, ether extract and ash equal to 72.2, 22.88, 3.05 and 1.84%, respectively. There was no effect of diets on CL, SF and color indices (Table 1). However, there was a tendency (P<0.10) of the beef from Nellore steers be less tender than Nellore x Angus, only 24 h after slaughter. Aging time increased tenderness and cooking loss; and reduced a* values. Beef from Nellore steers had lower CL. In conclusion, beef from Nellore are tougher than beef from Nellore x Angus steers after slaughter, but similar after 14 d of aging. In addition, color, cooking loss and chemical composition of beef from Nellore and Nellore x Angus steers are similar.

Table 1. Beef quality traits from Nellore and Nellore x Angus steers fed whole shelled corn diets

	Nellore		Angus x Nellore		SEM	P Value
	Time 0	Time 14	Time 0	Time 14		Breed	Diet	Time	Breed*Time
Tenderness	7.10	3.76	6.42	3.83	0.25	0.19	0.24	<0.01	0.10
Cooking loss	21.4	24.7	25.7	26.8	0.61	<0.01	0.48	0.01	0.13
L *	40.72	40.15	41.85	39.97	0.60	0.57	0.54	0.06	0.30
a *	18.77	14.1	19.29	13.82	0.41	0.83	0.44	<0.01	0.38
b *	12.07	12.73	13.02	12.62	0.28	0.30	0.56	0.71	0.14