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State College of Washington, Pullman
Abstract
Thirty-two gilts, from the eighth generation of an experiment designed to study the relationship between nutrition and improvement of animals for meat production through breeding were slaughtered to study carcass characteristics under four combinations of full and limited feeding.
The gilts selected from a background of full feeding showed more muscling than those selected from a background of limited feeding. The measure was the area of cross section of the longissimus dorsi muscle. Gilts from the background of full feeding averaged over
sq. in. greater development of loin eye (P<0.01). The results of this study indicate that a better job of selection for meat-type hogs, as based on muscular development, can be accomplished under full feeding, where the muscling is allowed to express itself to the fullest extent by selection time.
The plane of nutrition had a statistically significant effect upon carcass fatback (P<0.01). The full-fed gilts averaged 0.32 in. more backfat than gilts receiving 70% of full feed. When the 56.5 days difference in age between the two groups at slaughter was adjusted to a constant age, the full-fed gilts averaged 0.56 inch more backfat than the limited-fed gilts.
There was a statistically significant interaction between selection background and plane of nutrition On yield of trimmed primal cuts. Selection under full feeding favored a higher yield of trimmed primal cuts when such animals were placed on limited feeding. This genotype-environment interaction may partly determine whether breeding stock should be selected under the environment in which their progeny will be produced.
A highly significant correlation between live backfat probes and carcass fatback measurements was found.
1 Scientific Paper No.1729, Washington Agricultural Experiment Station, Pullman. Project No. 807.
2 In cooperation with Swift and Company, Chicago, Illinois, with added support from Carstens Packing Company, Tacoma and Spokane, Washington; Gibson Packing Company, Yakima, Washington; Pendleton Grain Growers, Pendleton, Oregon; American Dry Milk Institute, Incorporated, Chicago, Illinois; Hiram Walker, Peoria, Illinois; Standard Brands, Incorporated, New York, N. Y.; Charles Pfizer ana Company, Brooklyn, N. Y.
3 The advisory committee for this project is as follows: S. P. Swenson, Dean, College of Agriculture, State College of Washington, Pullman, Washington; H. E. Robinson, Director of Research, Swift and Company, Chicago, Illinois; E. J. Warwick, Director, Beef Cattle Breeding Research, U.S.D.A., Beltsville, Maryland; A. J. Wood, Department of Animal Husbandry, University of British Columbia, Vancouver, B.C, Canada; C. F. Sierk, State Experiment Stations Division, Animal Production Unit, A.R.S., Washington, D. C.; M. E. Ensminger, Chairman, Department of Animal Science, State College of Washington, Pullman, Washington; R. E. Wolf, President, Washington Swine Breeders Association, Tekoa, Washington.
4 Present address: Animal Industry Department, Louisiana State University, Baton Rouge 3, La.
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