Meat quality of bulls submitted to different strategy during the growing and finishing phase

Author(s)

Juliana Akamine Torrecilhas

• Document type: Doctoral Thesis
• Press: Jaboticabal. 2020-08-25.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal
• Defense date: 2020-05-05
• Advisor: Telma Teresinha Berchielli

Abstract

Our objective was to evaluate the supplementation strategy during the growing phase on the meat quality of bulls finished in pasture plus concentrate or feedlot. One hundred and twenty young bulls uncastrated males [10 ± 2 month old and 256.54 ± 28.92 kg of body weight (BW)] were blocked by weight and randomly assigned to treatments in 2 × 2 factorial design, two supplements during the growing phase: mineral (ad libitum - MIN) or Protein + Energy (0.3% BW/ animal/ day - PE) and two finishing system: pasture plus concentrate (2% BW/ animal/ day - PAST) or feedlot (25:75; corn silage: concentrate - FLOT). After 285 days the bulls (503.89 ± 56.61 kg) were slaughtered, the carcasses were divided medially from the sternum and the spine, resulting in two similar halves. The Longissimus thoracis (LT) sample (10 g) was removed immediately after slaughtered between 12th and 13th ribs from each animal and frozen (liquid nitrogen) for: lipogenic enzyme activity and relative abundance of mRNA associated with lipid metabolism measured by qRT-PCR, target genes include PPARγ, SREBP1c, SCD1, ACCα, LPL, FBP4, CPT2, ACOX, and PPARα. After 24 h carcass chilling, the pH was measured between the 12th and 13th ribs of the LT. The fat thickness and five steaks of 2.54 cm from LT (between the 9th and 13th ribs) were collected for fatty acid profile, chemical composition, shear force, sarcomere length, myofibrillar fragmentation index, thawing loss, cooking loss, water holding capacity, fat color, myoglobin, lipid oxidation and meat color which was measured on days, 1, 4, 7, 10 and 14 storage time exposed to oxygen at 0 ± 4°C. The FLOT system increased (P < 0.050) the fat thickness (7.01 vs. 3.07 mm), sarcomere length (1.59 vs. 1.42 µm), and decreased the meat shear force (36.29 vs. 43.20 N), while the PAST group showed higher (P < 0.050) water holding capacity (68.16 vs. 64.32%), yellowness fat (16.66 vs. 14.30), myoglobin concentration (4.56 vs. 3.95 mg/g of meat). The meat of bulls fed with MIN during the growing phase following by FLOT finishing showed increased (P < 0.050) of lipid oxidation compared to bulls from MIN following by PAST system (0.35 vs. 0.27 mg/kg of meat). During the storage time, the meat of bulls fed with MIN following by PAST system showed lower (P < 0.050) L* value compared to the other treatments. On days, 4 and 7 of the display, the FLOT group had increased (P < 0.050) of a* and C* in meat compared to PAST. The bulls from PAST system showed lower (P < 0.050) b* value compared to FLOT (12.17 vs. 13.40, respectively). The FLOT group had (P < 0.050) higher lipid content than PAST (2.72 vs 1.49%, respectively). The bulls fed with MIN following by FLOT system showed an increase (P < 0.050) of C12:0, C14:0, and C16:0 which led to greater saturation fatty acid total concentration. The bulls finished in FLOT system had higher (P < 0.050) monounsaturated fatty acid total concentration coinciding with the up-regulated (P < 0.050) of gene expression of SCD1 compared to PAST system. The meat of bulls from FLOT system showed a decrease (P < 0.050) of C18:2n6, C20:3n6, C20:4n6, C20:5n3, n6/n3 ratio and isocitrate dehydrogenase compared to PAST system. In addition, the animals fed with PRE following by FLOT finishing had higher (P < 0.050) CPT2 expression, while the MIN supplementation following by PAST system showed decreased (P < 0.050) of SREBP1c, increased (P < 0.050) CPT2 and PPARα expression. Globally, these results suggested which the attributes relationship with tenderness meat was not affected by the growing phase. The PAST system decreased the tenderness and lightness of meat, but these attributes still showed within the acceptable standards of the meat industry. In addition, the FLOT system increased the intramuscular lipid compared to PAST system, but the animals fed with MIN during the growing phase following by PAST showed greater genes expression related to lipid degradation and lower gene expression related with synthesis of lipids. (AU)

• FAPESP's process: 16/10953-3 - Growth physiology and meat quality of young cattle finished on pasture or feedlot submitted to different nutritional plans during the stocking phase
• Grantee: Juliana Akamine Torrecilhas
• Support Opportunities: Scholarships in Brazil - Doctorate