Effect of the finishing system, gain rate and slaughter criterion on the meat quality characteristics of Angus x Nellore cattle

Author(s)

Juan Fernando Morales Gómez

• Document type: Doctoral Thesis
• Press: Pirassununga.
• Institution: Universidade de São Paulo (USP). Faculdade de Zootecnica e Engenharia de Alimentos (FZE/BT)
• Defense date: 2021-04-30

Examining board members

Saulo da Luz e Silva; Luis Artur Loyola Chardulo; Mario Luiz Chizzotti; Mirele Daiana Poleti; Flávio Dutra de Resende

• Advisor: Saulo da Luz e Silva

Abstract

The aim of this study was to explore the impact of the gain rate (GR) and the finishing system on growth characteristics, muscle metabolism, post-mortem metabolism and meat quality of cattle slaughtered based on live weight (530 kg ± 20 kg) or feeding time (140 days). Seventy-two Angus x Nellore crossbred males were randomly assigned to one of four treatments: 1) feedlot, high GR (FH); 2) feedlot, low GR (FL); 3) pasture, high GR (PH); and 4) pasture, low GR (PL). Periodically throughout the study, the animals were weighed and evaluated by ultrasound for the muscle tissue and subcutaneous fat deposition. At slaughter, data on carcass characteristics were collected and Longissimus thoracis (LT) muscle was sampled for further in vitro glycolysis analysis. After 24 h of carcass cooling, LT muscle samples were collected for further analysis of metabolites and enzymes expression related to energy metabolism. In addition, LT muscle samples were collected to evaluate color and shear force at 3 aging times (0-, 7- and 14-days aging), in which samples aged for 7 days were also evaluated by a sensory panel of consumer acceptance. All data were analyzed using the MIXED procedure of the SAS software from a completely randomized design, in which the treatment was considered as a fixed effect and each slaughter criterion was analyzed separately. There was an interaction between treatment and feeding time for live weight and muscle and fat deposition in both slaughter criteria (P < 0.05). The FH and FL animals showed non-aged meat more tenderness with higher L* values when compared to PH and PL animals. However, meat from FH animals showed higher a* and b* values when compared to that from PH and PL animals (P < 0.05), while the meat from FL animals showed similar a* and b* values when compared to that from PH and PL animals. The aging process modified the beef color and shear force values, which also was dependent on the slaughter criterion. In the slaughter criterion based on weight, meat from FH animals showed higher L* values when compared with that from other treatments (P < 0.05), in addition to presenting higher b* values when compared with that from PH animals and PL (P < 0.05). However, in the slaughter criterion based on feeding time, meat from FH animals showed higher L* values when compared with that from PH and PL animals (P < 0.01), in addition to a higher a* and b* value when compared with that from other treatments when aged for 7 and 14 days (P < 0.05). In addition, aging for 14 days mitigated the difference in shear force between animals finished on pasture and feedlot when slaughtered based on weight (P < 0.05); however, this difference was not observed when animals were slaughtered based on feeding time (P > 0.05). In the sensory panel, consumers preferred meat from animals finished in feedlot (FH and FL) when compared to animals finished in pasture (PH and PL) (P < 0.01). Animals finished in pasture, mainly PL animals, showed a muscle energy metabolism more directed towards the oxidative pathway. In addition, PL animals showed higher pH values when compared to animals finished in feedlot when slaughtered based on feeding time (P < 0.05), which was not observed when the animals were slaughtered based on live weight. Therefore, the feeding system and GR have a pronounced effect on muscle metabolism and postmortem and, consequently, on meat quality, in which the finishing system appears to be the main responsible for the attributes of lightness, tenderness and sensory acceptance of the meat, while GR mainly has an effect on the chromatic attributes of meat color. In addition, the dark meat from animals finished on pasture may be related to light and lean carcasses and/or to a more oxidative muscle metabolism. (AU)

• FAPESP's process: 18/01434-8 - Effect of the finishing system, rate of gain and slaughter criteria on meat quality characteristics of Angus x Nellore cattle
• Grantee: Juan Fernando Morales Gomez
• Support Opportunities: Scholarships in Brazil - Doctorate