Grade Standards For Ovine Carcasses

Grade Standards For Ovine Carcasses - GRADE STANDARDS FOR...

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Unformatted text preview: GRADE STANDARDS FOR DVINE CARCASSES D. E. Eversole I HIETQR! Official standards for quality grades for ovine carcasses and slaughter ovines were initially promulgated by the United States Department of Agriculture (USDA) in 1931 and have been revised on four occasions since that time. Yield grades were adopted in 1969 for use in conjunction with the quality grades on a voluntary basis by users of the Federal grading service. The development of the yield grade standards was prompted by USDA’s recognition of significant differences in the fatness of sheep and thus in retail yields and value of the ovine carcasses being produced. The yield grade standards for ovines were patterned in concept upon the yield grades for beef, which were adopted in 1965, and were based on research (Journal of Animal Science 26:896) specifically designed to provide a scientific basis for grading. It has become increasingly clear in recent years that today’s consumers are demanding less fat in all of the products they buy. The beef and pork industries recognized these trends and have made significant strides in recent years in offering leaner cuts of these meats to consumers. The lamb industry has lagged in this regard and only recently has there been a consensus of opinion that some action must be taken to produce a leaner product. As a first step in producing a leaner product, they realized that there must be a method of identifying value differences in lamb carcasses. Everyone could then be compensated on the basis of the desirability of the type of product produced. A tool for implementing this is yield grades. As adopted in 1969, the yield grades for lamb carcasses were based on: 1) the adjusted 12th rib fat thickness over the ribeye; 2) the amount of kidney and pelvic fat; and 3) the leg conformation score. JUSTIFICATION 1) Use of yield grades was voluntary on the part of the users of the grading service. In their request to USDA, the lamb producers, represented by the American Sheep Industry Association (ASI), recognized that there would be no benefit derived if the yield grades were not used. Therefore, in order to assure their use, they requested that the regulations be changed to require that all ovine carcasses officially graded be identified for both quality grade and yield grade. As a result, the most complete information would be available to identify differences in value. 2) The kidney and pelvic fat of ovine carcasses has little or no value to retailers and consumers. However, because it contributes to dressing percentage (carcass weight as a percent of live weight), it does provide an economic incentive to make lambs overfat when producers/feeders are paid on the basis of carcass weights without consideration of yield grade. Therefore, ASI requested that the regulations be amended to require the removal of kidney and pelvic fat prior to the grading of ovine carcasses. Since removal of every bit of kidney and pelvic fat would not be feasible under some circumstances, the USDA felt that some tolerance should be allowed for this requirement. Subsequent consideration resulted in agreement between A51 and USDA that up to 1.0 percent of the carcass weight in Sidney and pelvic fat should be allowed in carcasses eligible for gra ing. 3) Leg conformation scores have been a part of the ovine yield grades since 1969, but their contribution to predictions of retail yield (as shown by the low value for leg score in the yield grade equation) was recognized as being slight. Because leg conformation is determined subjectively by visual inspection, variation in application of this factor is subject to error which may exceed its value in grading. These factors prompted A51 to suggest that leg score be dropped as a grade factor. If most of the kidney and pelvic fat is removed and leg conformation score is dropped, only fat thickness over the ribeye is left as the basis for determining the yield grade of ovine carcasses. Based on evaluation of a number of research studies published in the Journal of Animal Science and elsewhere, it was concluded that this factor alone (12th rib fat thickness) was of sufficient importance that it could be the basis of an accurate grading system. QUEBENT §TANQARD§ Effective July 6, 1992, the following standards in lamb carcass grading were implemented. 1) All ovine carcasses would be identified for both quality and yield grades when officially graded. 2) Carcasses with more than 1.0 percent of their weight in kidney and pelvic fat would not be eligible for grading. 3) Leg conformation scores would be dropped as a grade factor and the yield grade would be based on adjusted 12th rib fat.thickness over the ribeye. 4) The fat thickness range for each yield grade would be as follows: Yield grade Adjusted 12th rib fat (in) 1 0.00 - 0.15 2 0.16 - 0.25 3 0.26 - 0.35 4 0.36 - 0.45 5 3 0.46 APPLICATION OF YIELD GRADE SIANDARDS For carcass evaluation programs and other purposes when position within a yield grade is desired, each 0.01 inch change in fatness within these ranges would equate to a change of 0.1 yield grade. The following equation may be used to convert adjusted fat thickness to yield grade: Yield grade = 0.4 + (10 x adjusted 12th rib fat, in) Lamb 54.5 0.10 'na 'nal ESTIMATING YIELD Gm: ton was 1 FYG d Carcass data QG Dressing % 12th rib fat (in) ade FYG for lamb 1: 0.4 + (10 x 0.1) 1.4 ield rade FYG or amb : FYG 0.4 + (10 x .42) 4.6 51.8 0.42 PRICING LIVE LAMBS I. PRICING DATA A) Base YG 2.7 B) Pricing differential 20¢/.1 YG C) Choice lamb carcass $120/cwt. carcass D) Prime iamb carcass $122/cwt. carcass E) Use-actual dressing % to arrive at live price/cwt. Lamh_l 1000.2 $122.00 $120.00 + 2.60 (13 x 20¢) - 3,89 (19 x 20¢) 124.60 116.20 3 .545 (dressing %) g__;§1fi (dressing %) $ 67.91/cwt $ 60.19/cwt ...
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This note was uploaded on 10/18/2010 for the course APSC 4414 at Virginia Tech.

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Grade Standards For Ovine Carcasses - GRADE STANDARDS FOR...

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