Effects of production system and growth promotants on the physiological maturity scores in steers

Abstract

López-Campos, Ó., Aalhus, J. L., Larsen, I. L., Juárez, M. and Basarab, J. A. 2014. Effects of production system and growth promotants on the physiological maturity scores in steers. Can. J. Anim. Sci. 94: 607–617. Over a 2-yr period, 224 crossbred steers were allotted to a 2×2×2 factorial arrangement of treatments to determine the effect of the production system (calf-fed vs. yearling-fed), growth implant strategy (non-implanted vs. implanted) and β-agonist supplementation (no ractopamine vs. ractopamine) on physiological indicators of maturity. Dentition and ossification scores along the vertebral column were collected post-mortem during head inspection and grading. Dentition score was significantly affected (P<0.001) by production system, but not by implant (P=0.68) or β-agonist (P=0.31). There were significant interactions (P<0.001) between production system and implant strategy on the frequencies of carcasses showing ossification in the thoracic, lumbar and sacral vertebral processes. There was a significant interaction (P<0.0001) between the production system and implant strategy on the frequencies of the carcasses considered as <21 or >21 mo of age based on a segregation model using only physiological maturity assessments. These data emphasize the inability of physiological scores to accurately reflect chronological age, with overall classification accuracies of 0.68 and 0.53 for dentition and ossification scores. The highest overall classification accuracies were obtained using the thoracic (0.74) or lumbar (0.69) ossification scores. Implants accelerate the ossification process, particularly in younger animals, thus having a dramatic effect on numbers of animals eligible to be categorized as <21 mo of age based on physiological maturity evaluation.

Carcass and Primal Composition Predictions Using Camera Vision Systems (CVS) and Dual-Energy X-ray Absorptiometry (DXA) Technologies on Mature Cows

“…Following 72 h of chilling at 2 °C, left carcass sides were weighed (CCW) to determine shrink loss. Physiological maturity of the carcasses were assessed based on the extent to which caps of the spinal processes and ribs had ossified (i.e., >50% ossification, a carcass receives a D grade) in accordance with López-Campos et al [ 22 ] and the Canadian Beef Grading Agency (CBGA) [ 2 ]. Left carcass sides were then knife-ribbed between the 12th and 13th ribs.…”

“… 1 SD: standard deviation; 2 HCW: Hot carcass weight; 3 CCW: Cold carcass weight; 4 Rib-eye width and length, and muscle score in agreement with Jones [ 24 ] and Segura et al [ 25 ]; 5 LMY: estimated total lean meat yield [ 25 ]; 6 RCY: retail cut yield [ 25 ]; 7 Marbling scores: Official United States Standards for Grades of Beef Carcasses (marbling scores: 0 = Devoid, 100 = Practically Devoid, 200 = Traces, 300 = Slight, 400 = Small, 500 = Modest, 600 = Moderate, 700 = Slightly Abundant, 800 = Moderately Abundant, 900 = Abundant) [ 23 ]; 8 Ossification (%): Ossification processes of the carcasses assessed on the caps of the spinal processes and ribs (i.e., >50% ossification, a carcass receives a D grade) according to López-Campos et al [ 22 ] and the Canadian beef Grading Agency [ 2 ]. …”

Influence of Production Factors on Beef Primal Tissue Composition

“…YF represents calves (usually lighter calves or smaller-framed calves with a higher percentage of British breeds) that were weaned at 6–7 months of age, fed a backgrounding diet (higher forage content) for 5–6 months, and then fed a high-concentrate diet until slaughter at 20.80 ± 2.51 months of age. The PS and implant groups have been described in detail in previous publications [ 11 , 21 , 25 , 26 ]. Steers also belonged to two different growth implant groups: animals with implants (IMP) and animals without implants (no IMP).…”

“…Their effect on carcass and meat quality traits such as marbling, however, remains contradictory [ 16 , 17 , 18 , 19 ], which may be due to interactions with other factors such as breed composition [ 20 ]. Few studies have modeled the interaction between these production factors as a contributor to the variance of carcass merit traits [ 10 , 20 , 21 ], but the variation in tissue composition of individual primal cut due to the interactions among these factors remains unexplored.…”

Tenderness and sensory attributes of 11 muscles from carcasses within the Canadian cull cow grades

“…Specified risk materials must be removed from these carcasses prior to processing. As dentition scores are not well correlated with ossification scores (Lawrence et al 2001;López-Campos et al 2014), some carcasses which are OTM by dentition are considered youthful by ossification (i.e., on the basis of ossification these animals would not receive a D grade). Rodas-González et al (2013) profiled carcass traits and composition from mature carcasses graded within the Canadian standards and found D1 and D4 carcasses possessed higher marbling than youthful beef [under 30 mo (UTM)]; higher marbling has been shown to improve palatability and consumer acceptance (Savell et al 1987;Neely et al 1998;Killinger et al 2004).…”