Mohammad Koohmaraie

Effects of in-plant interventions on reduction of enterohemorrhagic escherichia coli and background indicator microorganisms on veal calf hides

Enterohemorrhagic Escherichia coli (EHEC) serotypes in veal have recently been recognized as a problem. Because hides are considered to be the principal source of EHEC and hide interventions have been shown to be very efficacious in the control of EHEC in beef processing plants, various hide-directed intervention strategies have been implemented in several veal processing plants to mitigate contamination. We evaluated the effectiveness of three different hide interventions used at veal processing plants: A, a water rinse followed by a manual curry comb of the hide; B, application of 200 ppm of chlorine followed by a hot water rinse; and C, a 5-min treatment with chlorine foam followed by a rinse with 180 to 200 ppm of acidified sodium chlorite. The levels of total aerobic bacteria, Enterobacteriaceae, coliforms, and E. coli, as well as the prevalence of Salmonella, E. coli O157:H7, and non-O157 EHEC, were determined on hides pre- and postintervention. Interventions A, B, and C reduced indicator organisms (P < 0.05) by 0.8 to 3.5 log CFU, 2.1 to 2.7 log CFU, and 1.0 to 1.5 log CFU, respectively. No Salmonella was detected on hides prior to intervention. E. coli O157:H7 prevalence was observed at only one plant, so comparison was not possible. Other non-O157 EHECs (O26, O103, and O111) were observed for all interventions studied. Interventions A and B reduced culture-confirmed non-O157 EHEC by 29 and 21 % , respectively, whereas intervention C did not reduce non-O157 EHEC. Our results show that the most effective veal hide intervention for reducing indicator organisms and EHECs was the application of 200 ppm of chlorine followed by hot water rinse. These data provide options that veal processors can consider in their EHEC control program.

Performance, Carcass and Meat Quality Traits of Najdi Lambs Fed Saltbush and Date Pits

Abstract Sami, A., Al-Owaimer, A., Zahran, S. and Koohmaraie, M. 2010. Performance, carcass and meat quality traits of Najdi lambs fed saltbush and date pits. J. Appl. Anim. Res., 38: 77–80. To investigate the effect of feeding saltbush and ground date pits on the performance, carcass characteristics and meat quality traits, 60 Najdi lambs (23±0.43 kg, 3 mo) were randomly divided into 5 equal groups and fed on a barley based diet containing alfalfa hay (Control), Atriplex halimus (saltbush) or salt bush with 3 levels (15, 30 or 45%) of ground date pits (GDP) replacing barley. After 84 d, 6 lambs from each group were randomly chosen and slaughtered. Salt bush with 30% date pit group recorded highest daily gain with maximum dressing per cent and back fat thickness, whereas, saltbush alone resulted in poor growth, feed conversion efficiency, dressing per cent and back fat thickness. It is concluded that 20% saltbush, 30% date pit with barley soybean meal based concentrate mixture can be recommended for Najdi lambs.

Effects of cold shortening and cooking rate on beef tenderness

A study was conducted to determine if excised, cold-shortened muscle improves in tenderness with refrigerated aging. Changes in muscle tenderness due to cooking rates were also evaluated. Beef ribeye and shoulder clod muscles from the left side of 12 carcasses were removed 45 min postmortem and placed in an ice bath to induce cold shortening. Corresponding muscles from the right side were chilled conventionally on the intact side. One-inch steaks from these muscles were either frozen at 24 hours or aged for 14 days at 40oF before being cooked and analyzed. Steaks were analyzed raw, or cooked to 160oF internally in a oven at 200 (SLOW) or 500°F (FAST). Sarcomere length (degree of contraction), tenderness, and the extent of degradation of structural proteins were measured. Rapid chilling caused severe muscle contraction, which had a dramatic toughening effect. At 24 hours, the coldshortened muscle showed less protein degradation than conventionally chilled muscle. After aging 14 days, tenderness had improved and protein degradation had occurred in both cold-shortened and conventional muscles, but degradation was still less in cold-shortened muscles. The improvement in tenderness and the increase in protein degradation from 1 to 14 days were equal between cold-shortened and conventional chilling treatments but the coldshortened muscles remained tougher. FAST cooking resulted in greater cooking losses and greater sarcomere shortening than SLOW cooking. Cooking rate did not affect the tenderness of ribeye steaks, but SLOW cooking improved the tenderness of shoulder clod steaks that are higher in connective tissue. Extreme chilling conditions, which induce cold shortening, may reduce protein degradation beyond the effect of shortening. Although aging improved the tenderness of cold-shortened muscles, they remained tougher than their conventionally chilled counterparts.

Evaluation of attributes affecting tenderness differences between Bos taurus and Bos indicus cattle

This report is brought to you for free and open access by New Prairie Press. It has been accepted for inclusion in Kansas Agricultural Experiment Station Research Reports by an authorized administrator of New Prairie Press. Copyright 1990 Kansas State University Agricultural Experiment Station and Cooperative Extension Service.