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Evaluation of Slaughter Goat Selection and Goat Meat Classification Systems
by
Frank Pinkerton, Ph.D.
Ken McMillin, Ph.D.
Dr. Frank Pinkerton

e-mail: the_goatman@intrastar.net
Ed note: this article first appeared in the February, 2000, Goat Rancher magazine. Reprinted with permission of the author.

Preface

Live animal and meat grading/classification systems facilitate the flow of products through the constrictive link between the broad production base and the diverse consumption base that collectively is known as the market. The sorting and information filtering that occurs in the marketplace provides a common language for determining price differentials and feedback from consumers to producers. In general, marketing systems for red meats have evolved into highly complex, organized distribution channels from producers to slaughterers/processors to institutional firms and retail outlets. Such meats are traded in sufficient quantities to require common terminology, specifications, and standards for buying and selling carcasses, primal cuts, or case-ready retail portions. These market communication and classification systems are now commonplace with the notable exception of goats and goat meat. Accordingly, the goal of the research reported below was to develop a similar, practical system for goats and goat meat.

Introduction

The USDA Agricultural Marketing Service Grading and Standardization Branch has developed Institutional Meat Purchase Specifications (IMPS) for fresh beef, lamb and mutton, veal and calf, pork and fresh venison. Additionally, IMPS series for cured, cured and smoked, and full-cooked pork products; cured, dried, smoked and fully-cooked beef products, variety meats and edible by-products, and sausage products have been developed to fulfill the need for standardized terminology and classification systems for these items. The original IMPS were developed in the late 1950's by USDA in conjunction with interested procurement agencies and suppliers. They replaced the National Association of State Purchasing Officials (NASPO) specifications for meat products. The IMPS are mandatory only when specifically included in procurement contract provisions and are maintained as voluntary consensus specifications that reflect both purchaser demand and products that industry can produce. The North American Meat Processors Association has published a color directory of institutional cuts that are closely aligned with the IMPS cuts.

The IMPS standards facilitate communication within and between market sectors by providing data to be specified by the purchaser, e.g., weight ranges of carcasses and cuts, weight and thickness tolerances, cutting instructions, special material requirements, and specific item descriptions. Development of quality assurance provisions provide for product examination to determine defects and quality acceptance of IMPS cuts.

A corollary result of our earlier research on branded goat meat specifications (McMillin et al., 1997) was a preliminary investigation of IMPS requirements and fabrication techniques for goat meat carcasses and cuts. Our current research promotes the development and, hopefully, widespread adoption of standardized market communication for goats and goat meat which could do much to bring order and stability to current goat meat marketing channels (now characterized as being poorly structured, lacking in standardized processing techniques, and having inadequately developed product identification and distribution (Pinkerton, 1995).

Commercial utilization of new IMPS standards for goat meat would require a corollary scheme of live and carcass classification. Live standards that accurately correlate with carcass traits and meat characteristics have been successfully implemented for a few of the other livestock species, and preliminary data (McMillin et al., 1997) have illustrated the feasibility of developing such classifications for goats, at least for Spanish meat-type kids over limited weight ranges. Evaluation of additional breed types, ages, weights and body conformations typical of slaughter goat populations in the U.S. are needed to more fully develop a useful classification scheme for live goats and goat meat in marketing channels. Subsequent educational programs for those market players that would gain from uniform classification systems would promote the adoption of these systems in industry practice.

Research Objectives

The overall objective of this research was to develop sorting and classification systems to facilitate live goat marketing and goat meat purchasing in wholesale and retail channels. More specific research objectives were to: 1) Sample a variety of Angora, Spanish, dairy and Boer-cross goats to determine suitable live selection (classification) criteria for use in live goat marketing channels. 2) Provide data on different IMPS item specifications and primal cuts from goats of varying weights, sizes, and breed types to develop preliminary IMPS guidelines. 3) Survey auction markets, goat traders, meat wholesalers, and institutional goat meat purchasers to determine the prospective usefulness of live goat classification criteria and goat meat IMPS in industry practice.

Research Procedures

Wether goats of four breed types (Angora, Spanish, dairy, and Boer X Spanish-cross), three ages (kid, yearling, and adult) and visual conformation scores (classification categories 1 through 3) were procured from several Texas and Louisiana ranches and delivered to the Southern University abattoir, Baton Rouge, LA in nine groups. Reflecting industry practices, 12 nannies were also included in the adult group of dairy goats. The numbers in each category for the 276 total goats are in Table 1.

Table 1. Numbers of goats in each age and breed category.
Age => Adult Yearling Kid
Angora 39 38 35
Boer-cross 0 11 47
Dairy 17 2 9
Spanish 10 28 40

After holding overnight (with water, but no feed), certain live linear measures were taken on each goat: length of rump, loin, and chine; chest and shoulder widths; chest depth; height at withers and at hip; barrel circumference; and heart girth. Body conformation scores were assigned by experienced livestock graders using declining gradations of prime, choice, good, and cull. Thereafter, still slide photographs and videotapes were made of individual goats to enable review when comparing live grades to carcass grades.

Live (shrunk) weights were taken just prior to slaughter by humane procedures after which the hot carcasses were weighed and then chilled at 34?F overnight. The next morning an experienced meat grader assigned scores for carcass conformation using declining gradations of prime, choice, good, and cull. Carcasses were also visually appraised for percentage of kidney and pelvic channel fat, color of flank lean, and fat cover over the rib cage. Objective color of lean in the flank and semimembranosus muscle on the outside of the rear leg was determined with a portable reflectance colorimeter. Photographs and videotapes of side and rear views of each carcass were made for comparing carcass grades to live grades. Dressing percentage was calculated as hot carcass weight divided by live (shrunk) weight x 100%. Chilled carcass weights were recorded following cooling overnight.

Results and Discussion

The population of goats chosen for the project were selected to be representative of those entering the marketing and meat channels in the U.S. Ages of goats were not precisely known and researchers relied on teeth count to separate kids, yearlings, and adults. Of the goats selected for this study, the Boer-cross kid goats were heavier (P<0.05) than the kid goats of the other three breed types, Spanish and Boer-cross yearling goats were heavier (P<0.05) than the Angora and dairy yearling goats, and the dairy adult goats were heavier (P<0.05) than the Angora and Spanish adult goats.

Boer-cross kids were longer (P<0.05) through the rump, loin, and chine, had wider (P<0.05) and deeper (P<0.05) chest dimensions, and had larger (P<0.05) heart girth and barrel circumference measurements than kid goats of the other breeds. Spanish yearling goats had slightly greater dimensions at each location, including height at withers and height at hip (P<0.05), than Boer-cross yearlings, which could indicate differences in maturation patterns between the two breeds. Angora goats had smaller dimensions at each age compared with goats of the other breeds. Yearling goats of each breed generally had greater dimensions at each location than kid goats of the same breed and adult goats correspondingly had greater dimensions than the yearling goats. Spanish and Boer-cross kid and yearling goats had higher subjective live conformation scores than Angora and dairy kid and yearling goats.

The live animal traits were generally highly (P<0.0001) correlated with one another, indicating that animals that were larger in one measurement were usually larger in another similar measurement. An exception was the live conformation score. The subjective live conformation score was highly (P<0.005) related to chest width and barrel circumference measurements, but not to other linear or dimensional live animal traits. This suggests that the measurements of several dimensional traits should be combined to result in an overall conformational image of the live goat. Alternatively, it may be that the live measurements that were chosen, based upon common measurements of dairy and breeding goats, were not precise enough to define the differences in conformation or shape of meat goats.

Based upon the body dimensions and live conformation scores, project scientists then determined the parameters that were deemed to be important in the sorting and marketing of live goats and thereafter devised four classification groups. Selection classification group one included goats with conformation scores of high choice and prime. Selection classification group two included goats with conformation scores of average and low choice. The third selection group contained goats with good conformation while the fourth selection group contained goats with inferior conformation. The descriptions of goats chosen in each selection classification group are in Table 2. (Pictures of the representative goats in the selection classification groups are in the Final Report to USDA-AMS and will be released following final approval and adoption.) Additional classification criteria that are important in distinguishing between market goats are age, sex class, and weight in addition to the conformation, muscling and shape that determine the selection classification group. Some of the USDA Market News Reporters have adopted these market goat category recommendations and are now reporting live goat prices based upon age, selection group, weight, and sex. (See the Internet market reports from the San Angelo, TX auction, Ms. Becky Sauder, reporter; www.ams.usda.gov/lsg/mncs/ls_satx.htm)

Table 2. Descriptions for live classification group criteria of market goats.
SelectionGoat description
1Goats possessing minimum qualifications are moderately thickly muscled throughout. The back and loin are moderately wide and shoulders and hips are moderately neat and blend smoothly into the body. There is a slight fullness or plumpness over the rib, loin, rump and legs that contributes to a somewhat rounded and moderately refined appearance.
2Goats possessing minimum qualifications are slightly thickly muscled throughout. The back and loin are slightly wide with loin, rump, and leg almost flat with little or no evidence of fullness. The hips and shoulders are somewhat smoothly laid in, but appear slightly prominant and contribute to a slightly refined appearance.
3Goats possessing minimum qualifications are thinly muscled throughout. The back, loin, and rump are narrow with a slightly sunken appearance. Legs are tapering and narrow with hips and shoulders somewhat prominent. Goats usually show either heavy bones and thin fleshing associated with coarseness or small bones and angularity denoting over-refinement.

Cull

Goats possessing cull qualifications are very thinly muscled throughout. The back, loin, and rump show little indication of muscling and have moderate to great shrunken appearance. Legs are very tapering and narrow with hips and shoulders very prominent. Goats are often those culled for inadequate frame size or body capacity or those with reproductive deficiencies.

Although we took exhaustive carcass measurements and examined many relationships among them, we present below only those findings we feel to be of relevance and interest to producers.

The hot carcass weights of the goats were closely related to the live weights (r = 0.92). Boer-cross kid goats had heavier (P<0.05) hot carcass weights than kid goats of the other three breeds and Spanish and Boer-cross yearling goats had heavier (P<0.05) hot carcass weights than the Angora and dairy yearling goats. The adult dairy goats had heavier (P<0.05) hot carcass weights than Angora and Spanish adult goats because the live weight was much heavier. There were only slight variations in dressing percentage or yield of hot carcass between breeds. Dressing percentage was lowest for Angora kid goats and tended to be lower for dairy goats of each age group when compared to goats of the other three breeds for each respective age group. Average dressing percentages across age groups were 48 to 54% for Spanish and Boer-cross goats and 43 to 49% for Angora and dairy goats in this study. Cold carcass weight followed similar trends to the live weight and hot carcass weight data. The simple correlation between hot and cold carcass weight was very high (r = 0.96).

The carcass conformation scores (grades) were higher (P<0.05) for Boer-cross kid goats than for kid goats of other breeds. Spanish and Boer-cross yearling goats had higher (P<0.05) carcass conformation scores than Angora and dairy yearling goats. The simple correlation between live conformation score and carcass conformation score was 0.57 (P<0.01), which indicated a moderate to high relationship between the subjective scores. (It was noticed that the assigned live score became closer to the carcass score as the study progressed (practice does make perfect, here as elsewhere).

The visually estimated kidney and pelvic fat percentage was higher (P<0.05) in Boer-cross kid goat carcasses compared with the carcasses from other breeds of goats. Spanish yearling goat carcasses had greater (P<0.05) amounts of estimated kidney and pelvic fat than carcasses from yearling goats of the other breeds. Carcasses of dairy adult goats had the greatest (P<0.05) amount of estimated kidney and pelvic fat. The actual (weighed) percentage of kidney and pelvic fat was similar to the estimated kidney and pelvic fat percentage, the simple correlation being 0.82.

The subjective flank color score was lighter, indicating less maturity, in carcasses from younger goats. Flank color in carcasses of Boer-cross kid goats was darker (P<0.05) than the flank color in carcasses of goats from the other breeds. The flank color of Angora yearling carcasses was similar to that of carcasses from Boer-cross kid goats and much lighter (P<0.05) than the flank color of carcasses from yearling goats of the other breeds.

The objective lightness color of leg and flank was decreased with increased age of goats. Leg color was lighter (P<0.05) in carcasses from Angora and dairy kid goats compared with carcasses from Boer-cross and Spanish kid goats. Similar trends were observed for flank lightness values.

The color of lean is very important to some purchasers of goat meat, with a lighter, pinker color being perceived to be associated with meat from younger (and presumably more tender) goats. The current data with subjective flank color and objective leg and flank lightness values would generally support the concept of lean from younger animals being lighter in color, but the simple correlations of subjective flank color with any of the objective colorimeter measurements values were low, less than r = 0.40. The relationships between lightness of flank and leg, redness of flank and leg, and blueness of flank and leg as measured by the colorimeter were also low (r ? 0.50). Color is a very complex measurement and no single color measurement on a carcass seemed to precisely measure the color as perceived by a trained human evaluator.

The subjective external fat score increased with animal age of carcasses from Angora, dairy, and Spanish goats. The Boer-cross kid goats had received some grain and had slightly higher levels of external fat than the Boer-cross yearling goats that were raised only on pasture. It was anticipated that external fat would increase in goats of older ages as a normal indication of increased animal maturity. The external fat score was correlated with estimated kidney and pelvic fat (0.60) and actual kidney and pelvic fat (0.56). Readers should be aware that growing/aging goats deposit fat first (and in the greatest quantity) in the kidney/pelvic region and secondly over the rib cage. Only rarely does a goat get enough extra feed to lay down fat along the top if its back; similarly with marbling (the intramuscular deposition of fat). Other red meat species are specifically fattened in feedlots to have excessive external fat that is deposited somewhat uniformly along the back and over the ribs before marbling is deposited inside the muscle.

Carcass classification groups were developed based upon the relative carcass conformation (appearance and shape). The descriptions for the carcass classifications are in Table 3.

Table 3. Descriptions for carcass classification group criteria of market goats.
SelectionGoat description
1Carcasses have a superior meat type conformation and are thickly muscled throughout the body. Rib, loin, rump, and legs show particular fullness of muscling. Lean color is pale red to slightly pink. Fat cover score is 2 or
2Carcasses have an average meat type conformation, with a moderate degree of muscling throughout the body. Rib, loin, rump, and legs may be almost flat. Lean color is pale to moderately red. External fat cover must not completely cover the legs or shoulders, with a fat cover score of less than 3.
3Carcasses have a meat type conformation, with a thin degree of muscling throughout the body. Rib, loin, rump, and legs are narrow and may be slightly sunken or hollow. Lean color is pale to moderately red.

Cull Goats have a poor meat type conformation, with less than thin degree of muscling throughout the body. Rib, loin, rump, and legs are very narrow and flat, with definite signs of being sunken or hollow. Lean color is moderately red to very dark red.

Mathematical correlations between live traits and carcass traits were determined. Hot and cold carcass weights were each highly related to live dimensional measurements, but not to live conformation score (grade). Indeed, as indicated earlier, only two live goat measurements (chest width and barrel circumference) were significantly correlated with subjective live goat conformation grades. Worse still, we did not find any of the live measurements to be closely related to carcass grade. However, we did find a rather close and repeatable relationship between live conformation grade and carcass conformation score (r = 0.57); both are, of course, subjective, not empirical. In practical terms, this means that trained live goat graders (and experienced commercial buyers) can predict with reasonable accuracy the corresponding grade of the chilled carcass and, accordingly, estimate carcass monetary worth and, by calculation, live price per pound to be paid. The phrase "reasonable accuracy" is here purposely employed. Similarly, precise descriptions of carcass quality characteristics are exceptionally hard to devise. Indeed, author Pinkerton, speaking at a 1993 Boer goat symposium in Canada, suggested that "assessing meat goat quality is rather like appraising pornography- it is fairly easy to do, but it is pure hell to describe." His position remains unchanged some thousands of goats and hundreds of carcasses later.

To meet research objective two (develop preliminary IMPS guidelines), carcasses were fabricated into prototype IMPS cuts, with feedback from AMS personnel. These cuts were predicated upon preliminary cutting of carcasses into primal and subprimal cuts weighing 2 to 5 pounds, with additional criteria of cuts being easily made with a power saw or knife, cuts being made along natural muscle seams or at easily determined carcass locations, and cuts looking attractive with an optimal amount of lean mass per cut. After exploratory efforts, five cutting styles were developed, based upon the relative carcass weights. These styles and the weights (average and ranges) for the major cuts in each style are shown in figure 1. Platter style goats have intact carcasses weighing less than 15 pounds with only the trotters removed. Front legs are folded into the tendinous joints of the hind legs before chilling. Roasting style goat carcasses weigh 16 to 20 pounds and have large primal cuts suitable for roasting similarly to platter goats. Barbeque style goat carcasses weigh 21 to 30 pounds and are characterized by removal of the fore arm from the body and leaving the shoulder and rib area attached in a large piece. The weight of Southern style goat carcasses is 31 to 40 pounds, with six major cuts having generally larger weights than for the other carcass styles. Hotel style carcasses weigh more than 40 pounds, with cuts designed to provide larger portions for the hotel, restaurant, and institutional purchasers who will be cutting smaller portions on demand for their patrons.

To achieve objective 3, we interviewed selected Texas goat producers and various industry representatives to get their opinions and comments on our live and carcass grading systems and on our suggested IMPS cutting styles and related topics.

Most of the participants agreed that market news reporting services were useful to them in goat selling or buying. A lesser number thought that more market classifications would increase prices for goats and that the number of market classifications in the market news reports had increased recently; they credited our research findings, as applied by AMS market reporters and some of their state counterparts. Most responses indicated that pictures or charts of classification groups would be useful, that uniform evaluation criteria would likely increase prices of goats, that uniform evaluation criteria would likely increase sales of goat meat, that standardized cutting methods would facilitate purchase and selling of goat meat, and that increased goat meat purchases by restaurants and retail stores would likely increase goat prices. Fewer survey respondents agreed that uniform carcass evaluation systems would promote transport of carcasses instead of live goats.

Discussions with the producers indicated that other changes within the goat industry are needed in addition to classification systems and IMPS cuts. Assistance with production practices and more producer education programs were desired. Producers were receptive to IMPS, feeling that the system could improve institutional purchases of goat carcasses and meat over time. It was felt that the classification systems for live goats and goat carcasses might improve farm prices if the systems were widely adopted in the market channel.

Project personnel met with slaughter representatives in western Texas and gained their opinions of the classification systems and IMPS cuts. A trip was made to the NJ and PA areas near New York City to visit auction markets, processors, and retailers of goat meat. No formal surveys were taken of the individuals in Texas and New York City area because it was felt that informal conversation would result in more accurate and detailed responses to inquiries into their businesses. In general, the individuals in the middle of the marketing chain of live goats to consumers were not receptive to any imposition of live or carcass classification systems since the current marketing procedures would appear to be skewed to their advantage from supply and price perspectives. Processors and wholesalers to retailers in ethnic-oriented markets were noncommittal or only slightly interested in use of IMPS in current marketing of goat meat. A prevailing opinion was that retail stores wanted to purchase whole carcasses rather than cuts because their ethnic customers wanted to see the carcasses being made into cuts. Some processors conceded that IMPS would likely have utility for competitive bidding purposes by institutional purchasing agents. Processors in Texas and the NYC area generally thought that there was no lack of slaughter capacity, that the site of production does highly influence the location of slaughter facilities, that the hotel trade currently is for lighter weight carcasses (under 40 lb.), and that a grading system might aid in selling of goats and goat meat. The NYC processors indicated that there was concern with the quality and price of imported goat carcasses compared with domestic goat carcasses.

Summary and Conclusions

Our research resulted in live and carcass classification systems, provided data for preliminary IMPS goat meat cuts, and elicited insights from industry personnel on the usefulness and changes needed in the systems. Goats sampled from Texas and Louisiana farms and ranches were representative of those currently being marketed and provided sufficient variation to allow development of preliminary live goat and carcass classification systems. The elements of the live goat system were deemed successful because the general system is now being implemented for price reporting purposes by market news reporters in several locations. The IMPS cuts were developed and weights of the cuts were obtained to provide useful data for industry and to substantiate the draft IMPS cutting styles for carcasses of different weights. The draft IMPS are currently awaiting review and release by AMS, probably by early summer, 2000. Some of the more innovative cuts that were developed for goat carcasses may be adapted for the other red meat species IMPS. The survey of industry personnel provided an indication of the usefulness of the project and its results. The project provided a basis for establishment of uniform criteria for selection and classification of live goats and goat carcasses, developed a system of IMPS cuts to facilitate marketing of goat meat in institutional purchasing channels, and validated the research and development results through interviews with personnel representing all aspects of the goat industry.

Acknowledgments

State funds for this project and publication were matched with Federal funds under the Federal-State Marketing Improvement Program for the Agricultural Marketing Service, U.S. Department of Agriculture, as provided by the Agricultural Marketing Act of 1946. This project was a joint effort among investigators from the LSU Agricultural Center Louisiana Agricultural Experiment Station; Southern University College of Agriculture, Family and Consumer Sciences; Louisiana Department of Agriculture and Forestry; and USDA Agricultural Marketing Service. Special appreciation is expressed to Dave Foster and Mike Windham for live goat and carcass grading for the project and to Orlando Phelps for development of the draft IMPS.

Dr. Frank Pinkerton may be contacted via e-mail at the_goatman@intrastar.net

 

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