Effect of aging times and inclusion of unprotected or protected linseed oil from ruminal degradation on the diet of Nellore steers over pH and water holding capacity of meat

Abstract Text:

This work assess the effects of aging times and the inclusion of protected or unprotected linseed oil of rumen degradation on diet of 21 Nellore steers, finished at feedlot, over pH and water holding capacity (WHC) of Longissimus muscle. At the beginning of the experiment, the animals had 18 months of age and 397.74 ± 14.07 kg of BW and they were kept in individual pens and adapted during 21 days. The diets were composed by 40% corn silage and with no oil addition (73% TDN and 2.9% EE), with in natura linseed oil or with protected linseed oil (76% TDN and 6.1% EE). After 105 days at feedlot, the animals were slaughtered with 522.72 ± 27.99 kg of BW and carcasses were chilled for 24 hours. After this period, a section of the Longissimus between 6^th and 13^th ribs was removed and separated in 2.54 cm steaks, which were individually vacuum packed and chilled to 2 °C for one, seven or 14 days. The pH was determined using a pHmeter with a penetration electrode and the WHC was obtained by the difference between the weights of the meat samples of approximately 2 g before and after being submitted to pressure of 10 kg for 5 minutes. The results were submitted to analysis of variance using mixed models, considering a random block one, and a 3 x 3 factorial scheme. No interactions were observed between diets and aging times (P>0.05). No differences were observed for pH among treatments (P=0.9276) and aging times (linear regression - P=0.3454, and quadratic - P=0.3147), with an average of 5.45, considered normal for beef. The diets did not influence (P=0.7500) the WHC (74.61%), and for aging times, a quadratic effect (P=0.0286) was observed (69.27, 75.88 and 78.68% for one, seven and 14 days, respectively). The addition of linseed oil in any form on Nellore steers diet does not alter pH and WHC, however, aged meat for up to fourteen days is benefic because it increased the WHC, which influences many other aspects of meat quality, as juiciness.

Keywords: meat quality, Longissimus, zebu