Journal of Animal Science

Roubicek, C., B.;Ray, D., E.;Hale, W., H.

doi: 10.2527/jas1970.305675xpmid: 5420302

Summary Data from essentially unselected bull and heifer progeny of registered Hereford cattle were used to estimate mean concentrations and study genetic and broad environmental sources of variation in blood creatinine and uric acid. These cattle were maintained under ordinary semiarid range conditions. Individual animal weights and blood samples were obtained at 235, 340, 600 and 710 days of age for approximately 700 animals per sampling period. Herd size ranged from 280 to 435 cows with 9 to 12 sires per year. Year-of-birth effects were the most important source of variation considered for the blood constituents. Sex effect was significant at 340 and 710 days of age for creatinine and at all periods except weaning for uric acid. Sire effect was significant only at 600 and 710 days of age for uric acid. Heritability estimates for both creatinine and uric acid were essentially zero at all four sampling periods. Correlations of blood creatinine at the four ages were generally low and showed little relationship among the four periods. This content is only available as a PDF. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Bereskin,, B.;Shelby, C., E.;Hazel, L., N.

doi: 10.2527/jas1970.305681xpmid: N/A

Summary and Conclusions Originally, Wright (1921, 1922) proposed the quantity, F, as an inbreeding coefficient indicating “the departure from the amount of homozygosis under random mating to complete homozygosis.” F has since been used as a measure of such departure relative to a specified foundation stock, not necessarily random-bred (Wright, 1951). The most important inbreeding coefficient (Wright, 1951, 1955) and the one of concern here is the F-value pertaining to neutral autosomal disomic loei. In the strictest sense, F measures the changes in homozygosis (or, homozygosity) due only to parental relationship. Malecot (1948) showed that these changes in homozygosity also can be expressed in terms of probability. In biological populations, “true” F usually is indeterminable. The inbreeding coefficient, Fp, here, computed from parental relationships, commonly is used as an estimate of F (Wright, 1922; Lush, 1948). More information is needed on its correspondence with the actual state of homozygosity of an individual or population, particularly as it is affected by type of gene action and selection practices. This content is only available as a PDF. Author notes 2 Regional Swine Breeding Laboratory, A.H.R.D., A.R.S., with headquarters at Ames, Iowa. 3 Animal Science Department, Iowa State University, Ames. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Willham, R., L.

doi: 10.2527/jas1970.305690xpmid: 5463279

Summary Crossbreeding produces some desirable consequences. They are the production of heterosis, the opportunity to incorporate desirable genetic material quickly, and the chance to combine several desirable traits into a market animal. The primary factor involved in each consequence is genetic divergence as measured by gene frequency difference among the groups. The degree of dominance is important in the production of heterosis and combining several desirable traits. This content is only available as a PDF. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Cundiff, L., V.

doi: 10.2527/jas1970.305694xpmid: N/A

Abstract Selection and crossing of breeds are potential methods available to create genetic improvement. If non-additive and additive genetic variation are both important then improvement will be maximized by combining systematic crossbreeding with selection among and within breeds. In this manner, crossbreeding allows for utilization of heterosis and combining of desired characteristics in commercial cattle that would not be present in any parent breed alone. The purpose of this paper will be to review experimental results relating to choice of breeds. Considerable research has been conducted and much is in progress in the United States, primarily as a result of beef cattle breeding regional projects (W-1, NC-1 and S-10). The parameters of primary importance in choice of breeds are breeding values determined by average gene effects for the breeds and heterosis effects determined by interaction of gene effects and differences in average gene frequency between breeds (Willham, 1969). This content is only available as a PDF. Author notes 2 Beef Cattle Research Branch, Animal Husbandry Research Division, A.R.S., U.S.D.A., Lincoln, Nebraska. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Cartwright, T., C.

doi: 10.2527/jas1970.305706xpmid: N/A

Summary What the future holds is hazardous to predict and invites speculation but some trends are apparent. There will be increased emphasis on traits important for: (1) increasing output/input on a herd rather than individual basis, (2) specialized herds or breeds and (3) utilizing hybrid vigor. Evaluation criteria will be based on more discriminating classification than the customary dairy or beef. Classifications will include consideration of produce, market, breeding system and management system. Specialization will increase in commercial production and seedstock production. Breeds will emphasize selection goals for either sire lines or dam lines or both but in different herds, i.e., emphasis will shift from general purpose to special purpose cattle for both breeds and for breeders. F1's will become recognized and merchandized similarly to registered purebreds. Purebred associations will embrace the F1 and may introduce genes from exotic and dairy sources to broaden their genetic base and to enhance speed of specialization. This content is only available as a PDF. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Field, R., A.;Pearson, A., M.;Schweigert, B., S.

doi: 10.2527/jas1970.305712xpmid: N/A

Summary Bovine collagen from animals of different ages and from different anatomical locations within animals was analyzed by differential thermal analysis. Thermal transitions studied included the temperature at which the major part of the thermal transition begins to occur (extrapolated onset), the peak melting temperature and the range between these two points. Increasing the heating from 1 to 10 C/min. increased peak melting points of collagen approximately 4 C. Shrinkage temperatures were similar in Holstein calves, heifers, and cows. However, epimysial and intramuscular collagen from the longissimus melted at lower temperatures than that from the biceps femoris. Epimysial collagen also melted at lower temperatures than collagen from the subcutaneous fat or collagen from intramuscular tissue. As the extrapolated onset temperature of intramuscular collagen increased, shear values increased (r=0.47) and the melting range decreased. Relationships between the yield of labile collagen and thermal transitions approached statistical significance (P<.05). This content is only available as a PDF. Author notes 2 The senior author was on leave from the Department of Animal Science, University of Wyoming, Laramie, 82070, while conducting this study. 3 This investigation was supported in part by Public Health Service Research Grant No. FD-0097 from the Food and Drug Administration. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Field, R., A.;Pearson, A., M.;Magee, W., T.;Merkel, R., A.

doi: 10.2527/jas1970.305717xpmid: N/A

Summary Certain chemical and histological characteristics of the longissimus of seven yearling bulls selected for tenderness and seven yearling bulls selected for leanness were compared. Selection for tenderness in contrast to selection for percent trimmed round and loin since 1959 has not produced significant differences between the two groups for sarcomere length, fiber area, ultimate muscle pH, collagen content, labile collagen yield or proportion of α and β collagen sub-units in muscle. In addition, factors in epimysial tissue which have been associated with cross-linking of the collagen molecule were not affected. Muscle pH at 1 hr. postmortem was significantly lower in carcasses from the tender line of cattle when compared to those from the lean line. Both muscle pH and temperature at 1 hr. postmortem were closely associated with tenderness. This content is only available as a PDF. Author notes 2 The senior author was on leave from the Department of Animal Science, University of Wyoming, Laramie, Wyoming 82070, while conducting this study. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Link, B., A.;Bray, R., W.;Cassens, R., G.;Kauffman, R., G.

doi: 10.2527/jas1970.305722xpmid: 5420303

Summary The relative fatty acid composition of subcutaneous lipids was determined on fat biopsies obtained from steers and heifers at various stages of growth in two trials. The subcutaneous fatty acid composition was affected by changes in age and/or fattening and by season of the year. Fatty acid 18:0 decreased while 18:1 and 18:2 fatty acids increased as the animals increased in age. The relative amounts of 10:0, 12:1, 14:1 and 16:1 fatty acids were lower and 16:0 and 18:0 fatty acids higher during the cold winter months while the reverse was true during the summer. Subcutaneous lipid of steers had less 14:1 and more 18:2 fatty acid than heifers of the same age. Also, marked differences in relative amounts of fatty acids were noted between the two trials, suggesting that environment and genetics are important factors associated with such findings. This content is only available as a PDF. Author notes 2 Present address: Department of Animal Science, Texas A&M University, College Station. 3 Published with the approval of the Director of the Wisconsin Agricultural Experiment Station. Department of Meat and Animal Science Manuscript No. 558. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Link, B., A.;Bray, R., W.;Cassens, R., G.;Kauffman, R., G.

doi: 10.2527/jas1970.305726xpmid: 5420304

Summary The relative fatty acid composition of bovine intramuscular lipids was determined in two trials from muscle biopsies obtained from steers and heifers at various stages of growth. Seventeen fatty acids were identified of which 11 were different (P<.05) between animals of the two trials. The fatty acid composition was nearly identical between steers and heifers of the same age, even though degree of fatness was different. The polyunsaturated fatty acids, which are found primarily in the phospholipid fraction, decreased in proportion to the other fatty acids with increasing animal age and concomitant increases in intramuscular neutral lipid deposition. Changes in the relative amounts of 14:0, 16:0, 17:0 and 18:1 fatty acids during growth were related to the season of the year rather than animal age with the saturated fatty acids higher in the summer and lower during the winter. This content is only available as a PDF. Author notes 2 Present address: Department of Animal Science, Texas A&M University, College Station. 3 Published with the approval of the Director of the Wisconsin Agricultural Experiment Station. Department of Meat and Animal Science Manuscript No. 530. Copyright 1970 by American Society of Animal Science American Society of Animal Science

Miller, L., R.;Wheat, J., D.

doi: 10.2527/jas1970.305732xpmid: N/A

Summary Data from 3,024 barrows were used to examine the relationship between loin eye area and live weight, within the live weight range 82.0 to 110.0 kilograms. Barrows were divided into two groups, one group with adjusted live weight and the other group with actual live weight. Results were similar for the two groups, although the relationship between loin eye area and live weight was closer in the adjusted group. The adjustment of 0.14 cm2 per kilogram live weight approximates those derived in this study. These adjustments were for barrows only and most likely would not be the same as those for gilts and boars. Its derivation involved use of the logarithm of loin eye area and, thereby accounted for differential rates of loin eye area growth as influenced by area magnitude. This content is only available as a PDF. Author notes 2 Appreciation is expressed to the University Grants Program of Farmland Industries, Inc. The authors extend their gratitude to Dr. L. F. Tribble, for his assistance. Appreciation is also expressed to Mr. Karl Faidley, Mr. Keith Leavitt, Dr. B. B. Breidenstein, Mr. Carroll Plager and Mr. Bernard Ebbing for their cooperation in obtaining data. 3 Present address: U.S.D.A., A.R.S., Data Systems Application Division, % NAL, Route 1, Beltsville, Maryland 20705. Copyright 1970 by American Society of Animal Science American Society of Animal Science