Journal of Animal Science

Flock, D., K.

doi: 10.2527/jas1970.306839xpmid: 5422004

Abstract Estimates of genetic parameters vary considerably for most economie traits in farm animals which have been investigated extensively. Although several surveys have demonstrated that the published results vary less than expected considering the sampling distributions, the total range of available estimates likely includes some differences not adequately explained by the sampling variance. Two major reasons can cause these differences: (1) The source populations may differ in their genetic composition or may be tested under different conditions and (2) computational methods may bias the estimates in different ways. In this study, estimates of genetic parameters from hierarchal analyses of variance and covariance are compared with those from correlations between the progeny tests of sons and daughters and the progeny tests of their parents. Materials and Methods The data for this study came from 12 pig testing stations in West Germany. These have a total capacity of approximately 4,000 groups (2 barrows and 2 gilts) per year. This content is only available as a PDF. Author notes 1 Geneticist, Heisdorf & Nelson Farms; present address: 219 Cuxhaven, Am Seedeich 9, W. Germany. I would like to thank Dr. J. L. Lush and the referees for their helpful comments during the preparation of the manuscript. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Berruecos, J., M.;Dillard, E., U.;Robison, O., W.

doi: 10.2527/jas1970.306844xpmid: N/A

Abstract The development of a method for measuring backfat in the live pig by Hazel and Kline (1952) provided a new way for the improvement of carcass quality. Estimates of backfat obtained by this method are highly associated with carcass backfat (Hazel and Kline, 1952), total yield of fat (Zobrisky et al., 1959) and carcass merit (Robison et al., 1960). When compared with other methods of evaluating fat in a live animal, the probe method of Hazel and Kline (1952) was, in all cases, simpler, more accurate and quicker (Doornenbal, Asdell and Wellington, 1962, Pearson et al., 1957; Skjervold, Indrebo and Odegard, 1960). Thus, it appears that estimates of carcass fatness may be obtained quickly and accurately by this method. The effectiveness of improving carcass merit by selecting for reduced backfat depends on the heritability of backfat and its genetic correlation with carcass merit. Since reduced fatness in the carcass is greatly desired by the consumer, estimates of these genetic parameters are of particular interest. This content is only available as a PDF. Author notes 3 Animal Science Department. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Dickerson,, Gordon

doi: 10.2527/jas1970.306849xpmid: N/A

Summary Major biological objectives in reducing production costs per unit of animal product value seem to be (1) greater total product value per female (e.g., milk, wool, eggs) relative to metabolic body size, (2) higher rate of reproduction, especially in cattle and sheep, to reduce breeding herd costs per meat animal marketed, (3) more efficient lean growth to market live weight and earlier sexual maturity, with minimum increase in mature size of females, especially in cattle, and (4) combining female (milk or wool) production and progeny lean meat production under intensive management. Changes in management systems and in product values will modify specific biological objectives and hence need to be anticipated as well as possible. Breeding programs need balanced emphasis on (1) evaluation and utilization of existing breed differences in commercial livestock production, and (2) continuing genetic improvement within the pure breeds or strains. This content is only available as a PDF. Author notes 2 Animal Husbandry Research Division, A.R.S., U.S.D.A., Marvel Baker Hall, University of Nebraska, Lincoln. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Harris, Dewey, L.

doi: 10.2527/jas1970.306860xpmid: N/A

Abstract Most of the research work in animal breeding to date has been effectively concerned with methods of genetic evaluation and the nature of responses to selection. However, research leading to the complete definition of realistic selection goals does not seem to have been adequate. In this paper, the economic aspects of efficiency of production in meat animals will be considered. Suggestions will be made concerning information needed for the complete definition of selection goals and concerning utilization of these definitions to arrive at a selection criterion. Efficiency of production is an often mentioned objective of the meat animal industries as well as other agricultural industries. Efficiency is defined (Webster, 1956) as “effective operation as measured by a comparison of production with cost in energy, time, money, etc.” Three main aspects of efficiency in livestock production are: 1. Efficiency of animal industries relative to other food industries 2. Efficiency of animal industries relative to each other. This content is only available as a PDF. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Cross, H., Russell;Carpenter, J., W.;Palmer, A., Z.

doi: 10.2527/jas1970.306866xpmid: N/A

Abstract Over the last two decades, U.S. pork producers have concentrated on the production of carcasses having more lean and less fat. Producers have adopted and used scientifically based breeding, feeding and management practices and, accordingly, have accomplished a rapid improvement in pork carcass meatiness. With that improvement, an increasing number of well-muscled carcasses were observed that had acceptable quality but lacked the minimum backfat thickness for the number one Grade based on the Official United States Department of Agriculture Standards for Grades of Barrow and Gilt Carcasses (1958). The new official U.S.D.A. Standards (1968) give due credit to those carcasses. Further, the new Standards incorporate the use of a subjectively determined carcass muscling score in conjunction with previously used backfat thickness and carcass length or weight measurements to formulate the final carcass grade. Information is needed, however, on the extent to which muscling score contributes to a more accurate evaluation of pork carcass meatiness. This content is only available as a PDF. Author notes 2 Present address: Department of Animal Science, Texas A&M University, College Station, 77840. 3 Department of Animal Science. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Epley, R., J.;Hedrick, H., B.;Stringer, W., C.;Hutcheson, D., P.

doi: 10.2527/jas1970.306872xpmid: N/A

Summary The study which provided the basis for the development of the standards for yield grades of beef carcasses was reported by Murphey et al. (1960). The equation which was used as a basis for the yield grade standards was adpated from the regression equation, percent boneless retail cuts from round, loin, rib and chuck=51.34 −5.78 (single fat thickness over ribeye, in.) −.462 (percent kidney fat) + .740 area of ribeye, sq. in.) −.0093 (carcass wt., lb.). This equation was developed from data taken from 162 carcasses covering the full range of the quality grades (Prime to Canner) and included steers, heifers and cows. “When the U.S.D.A. equation is applied to another population of more homogeneous carcasses, one should not expect necessarily to obtain the exact relationship between estimated yield of retail cuts and actual yield of retail cuts as observed in the original U.S.D.A. study,” (Stringer et al., 1968). The objective of this study was to determine the predictive values of five carcass measurements when weight and percent retail cuts were predicted, using measurements taken from steer carcasses with a narrow range of quality grades and carcass weights. This content is only available as a PDF. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Miller, H., W.;Sanchez,, O.

doi: 10.2527/jas1970.306880xpmid: N/A

Summary Recently, increased attention has been given to direct and indirect measurements of beef carcass characteristics. Extensive research has been done to determine the relationship of certain carcass traits with physical, histological and biochemical characteristics of the meat. Several authors (Ramsey, Cole and Hobbs, 1962; Cole, Ramsey and Epiey, 1962; Brungardt and Bray, 1963) have reported significant relationships among bovine carcass fat measurements and carcass quality and cutability. Some workers (Bowland and Hironaka, 1957; Brungardt and Bray, 1966) noted significant correlations of plasma lipids with porcine and bovine carcass characteristics, respectively; however, Tremere, Owen and Bell (1966) reported no significant value in measurements of serum constituents as indicators of porcine carcass quality. The purpose of this study was to determine the relationship between the lipid and lipid fractions of blood and muscle and the quality and cutability-determining characteristics of bovine carcasses. Forty-three steers, self-fed a finishing ration (table 1) for 150 days were slaughtered at live weights ranging from 340 to 500 kilograms. This content is only available as a PDF. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Dockerty, T., R.;Ockerman, H., W.;Cahill, V., R.;Kunkle, L., E.;Weiser, H., H.

doi: 10.2527/jas1970.306884xpmid: N/A

Abstract Microbial spoilage poses many real problems to the meat industry. Decreased acceptability, resulting from changes in appearance and palatability, invites diminished. sales and further leads to reduced prices. Indirect losses are also incurred through the trimming of retail cuts, and, ultimately, through the reprocessing of fresh products to lower priced commodities. These losses must be absorbed by the retailer and reflect on the meat industry as a whole. The factors influencing the spoilage of fresh meat have not been studied extensively. Studies of such factors encompass three general areas of examination: (1) dressing, (2) wholesale cutting and shipping and (3) retail cutting and shelf-life of products. This study is concerned with the first of these areas of investigation—those factors associated with the dressing operation. Spoilage deep within those tissues derived from healthy animals is initiated by the sticking process (Jensen, 1954). However, a significant portion of the surface spoilage of cuts would appear to depend upon that originating at the carcass surfaces, subsequently being transferred to freshly cut surfaces by tools and hands. This content is only available as a PDF. Author notes 2 The authors express appreciation to Dr. W. R. Harvey and Mr. C. T. Gaskins for their assistance in the statistical preparation of the experimental data. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Luff, A., R.;Goldspink,, G.

doi: 10.2527/jas1970.306891xpmid: 5422005

Summary The total fiber numbers in the biceps brachii, anterior tibialis, extensor digitorum longus and the soleus muscles were examined in four strains of mice, C57, CIF, IF and dba. There were in some cases, significant differences in mean body weight and both absolute and relative muscle weights among the strains. Significant strain differences in mean total fiber numbers were noted for all muscles except the extensor digitorum longus. No consistent significant correlation was found between muscle weight and total fiber numbers. This content is only available as a PDF. Author notes 1 Present address: Department of Zoology, University of Toronto, Toronto 181, Ontario, Canada. 2 This investigation was supported by a grant from the Agricultural Research Council of Great Britain (to G. G.). 3 Department of Zoology. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Jurgens, M., H.;Peo, E., R.

doi: 10.2527/jas1970.306894xpmid: N/A

Abstract The American public has been made extremely conscious of the concept that saturated fat and cholesterol may be involved in atherosclerosis in man. Likewise, because of their content of cholesterol and saturated fatty acids, animal products have become engrossed in a controversy concerning their role in the atherogenic process. No definite conclusions have been made in this area and until further research advances in the field of atherosclerosis, the animal scientist may have to concern himself with modifying the animal product in such a way that it will be more acceptable to the American public. The degree to which this may be accomplished will vary with the species of animal. Swine are somewhat more unique in this respect because moderate changes in the diet can result in dramatic changes in the composition and type of fat deposited in the swine carcass. A review of the literature indicates few studies concerning the relationship between vitamin D and cholesterol—compounds functional in the body and which have a similar chemical structure. This content is only available as a PDF. Author notes 2 Present address: Iowa State University, Ames. 3 Department of Animal Science. Acknowledgement is made to John Welch for assistance in development of certain of the laboratory procedures and to P. J. Cunningham and associates for care of the experimental animals. Copyright 1970 by American Society of Animal Science American Society of Animal Science