Pork carcass composition, meat and belly qualities as influenced by feed efficiency selection in replacement boars from Large White sire and dam lines

This study evaluated carcass attributes, meat and belly qualities in finisher boars (n = 79) selected for feed efficiency (low, intermediate and high) based on estimated breeding value for feed conversion ratio within a Large White dam and sire genetic lines. The sire line had lower trimmed fat proportions and higher lean than the dam line (P < 0.01). Genetic lines expressed slight colour changes and drip losses (P < 0.05), with no differences in pH, marbling and cooking traits (P > 0.05). High-efficient animals presented the highest lean yield (P < 0.01), the lowest trimmed fat proportion (P < 0.01) and no effect on meat and belly quality attributes (P > 0.05) compared with other efficient groups. Interaction between efficiency group and genetic line was only detected for belly weight and thickness (P < 0.01). High-efficient animals offer a greater leanness level, with minimal impact on meat and belly quality traits.

Comparison of Lipid and Protein Oxidation Products and their Impact on Colour Stability in Bison Longissimus Lumborum and Psoas Major Muscles

ObjectivesTo compare lipid (malondialdehyde [MDA], 4-hydroxy-2-nonenal [HNE]) and protein (carbonyl content [CAR]) oxidation products and determine their influence on color stability in two bison muscles (longissimus lumborum [LL; color stable] and psoas major [PM; color labile]).Materials and MethodsA total of 10 longissimus lumborun (LL) and 10 psoas major (PM) from five A1 grade bison carcasses were obtained from a commercial slaughter plant within 48 h post-mortem. From each muscle, a 10-cm thick piece was removed and subsampled for evaluation of pH, MDA (by thiobarbituric acid assay), HNE (by ELISA) and CAR (by 2,4-dinitrophenylhydrazine). These measurements allowed the establishment of a baseline for the different oxidation products. The remainder of the muscles were cut into two equal portions, and each portion was vacuum-packaged and assigned to an ageing period of 7 and 14 d at 2°C. At the end of each ageing period, each muscle portion was removed from their packages, pH measured, and steaks obtained for sensory (muscle and discoloration scores) and instrumental color measurements (L*, a* and b*) over 5 d of retail display, and for estimation of MDA, HNE and CAR. After 5 d in retail display and following color and pH measurements the steaks were removed and collected for MDA, HNE and CAR determination. Data were analyzed as a completely randomized design with a split-split plot arrangement. Additionally, correlation and regression analysis were performed to identify the influence of the measured attributes on color.ResultsRegardless of the ageing time, LL showed greater redness and lower surface discoloration by instrumental (a* value; P = 0.04) and sensory (P < 0.01) color evaluation than PM at the end of the retail display. Furthermore, LL exhibited lower MDA, HNE and CAR content compared to PM (P < 0.05). A three-way interaction (muscle × ageing time × retail day display) was detected on MDA content, where PM presented a higher level of MDA with increasing ageing time and retail display than LL (P = 0.02). The pH was not different between LL and PM (P > 0.05) steaks.In both muscles, Pearson (r) and Spearman (rs) correlation coefficients indicated that MDA was the oxidation compound showing the highest correlation to a* (r = –0.78; P < 0.01) and discoloration (rs = 0.81; P < 0.01) scores, followed by a moderate correlation with HNE and CAR (r or rs < 0.7; P < 0.01). The pH did not exhibit correlation with color traits, except for lightness, in both muscles. For the stepwise regression analysis, the main variable entered into the equation for predicting a*, color and discoloration score in PM muscle was MDA with an R2 of 0.72, 0.75 and 0.78, respectively, while for LL muscle, MDA presented an R2 of 0.62, 0.68 and 0.66;, respectively. The pH, HNE and CAR only explained an additional 2% of the variation in those attributes.ConclusionThe results of color attributes corroborated that bison LL is a color-stable muscle due to the lower level of protein and lipid oxidation products developed during storage and retail display compared to PM muscle, which is considered color-labile muscle. The MDA seemed to have remarkable importance in the color deterioration than HNE and CAR, particularly in bison PM muscle.

Energy utilization in cattle with steady state and non-steady state methods: the importance of thermal neutrality

The efficiency by which animals utilize dietary energy is fundamental to the cost of production for protein of animal origin and to the carbon footprint an animal industry has. Hence, the development of cost effective methodology for determining these measurements of efficiency is important. The objective of the present study was to investigate the use of infrared thermography in a rapid, non-steady state method for measuring energy loss in cattle. Data from 241 yearling bulls and steers as well as heifers and mature cows are presented. Infrared images were collected following a 24h feed withdrawal period. The infrared thermal response in these animals was significantly ranked (P < 0.03) with conventional measurements of feed efficiency using residual feed intake values for animals demonstrated to be within a thermal neutral zone. When animals were not within a thermal neutral zone there was no significant ranking. The data suggests that the use of a non-steady state approach using infrared thermography for identifying metabolic efficiency in animals may be a more rapid and less expensive method for identifying differences in energy utilization. The data also demonstrates the importance of maintaining thermal neutrality when measuring metabolic efficiency irrespective of the methodology.

Salmonella and Escherichia coli O157:H7 prevalence in cattle and on carcasses in a vertically integrated feedlot and harvest plant in Mexico

To determine the prevalence of Salmonella and Escherichia coli O157:H7 in cattle feedlots and the impact of subsequent contamination on carcasses in a Mexican Federal Inspection Type Standards harvest facility, 250 animals were tagged and sampled in each step of the slaughter process. Samples were taken from hides and fecal grabs, and composite samples were taken from three anatomical carcass sites (hindshank, foreshank, and inside round) during the slaughter process, at preevisceration (PE), prior to entering the hot box (PHB), and after 24 h of dry chilling (DC). Additionally, 250 fecal samples were collected from the feedlot (FL), holding pens (HP), and intestinal feces (IF), and water samples were taken from the HP area. E. coli O157:H7 and Salmonella detection were carried out with the BAX System, immunomagnetic separation, and conventional methods. Overall Salmonella prevalence was 52.5%. The highest prevalence (92.4%) was found on hides, followed by feces from the HP (91.0%), FL (55.56%), PE (49.0%), IF (46.8%), and PHB (24.8%), for all sampling periods combined. The lowest prevalence of 6.0% was found after DC. The overall prevalence of E. coli O157:H7 was as follows: 11.7% for hides, 5.2% for IF, 2.7% for FL, 2.0% for HP, 0.8% for PE, 0.4% for PHB, and 0.4% for the cooler. High prevalence of Salmonella in IF and on hides present a significant risk factor for contamination by Salmonella at the different processing steps. These results serve as a warning as to the risks of contamination in meats for these pathogens and the importance of following good manufacturing practices during beef production processes.