EVALUATION OF PUREBREDS AND TWO-BREED CROSSES IN SWINE: FEEDLOT PERFORMANCE AND CARCASS MERIT

Feedlot performance of 941 barrows and gilts and carcass traits of 190 barrows of purebreds and crossbreds of the Duroc, Hampshire and Yorkshire breeds were evaluated for differences between purebreds and reciprocal crosses and for heterosis. Purebred and crossbred litters were farrowed contemporaneously at the Ft. Reno Experiment Station in the 1971 spring and fall farrowing seasons. Rather distinct differences between the pure breeds were evident for most traits. In general, Durocs gained weight more rapidly than Hampshires and Yorkshires while Yorkshires were the most efficient pure breed. Hampshire barrows had less backfat, more loin eye area and more total yield of lean cuts than Duroc or Yorkshire barrows, however Duroc barrows were superior to the other breeds for quality scores of marbling, firmness and color. Heterosis, defined as significant deviation from the average of parental breeds, was found for average daily gain on test (10.2%), age at 100 kg (5.2%) and average daily feed intake (5.9%). There was little evidence for heterosis for carcass measurements or yield of lean cuts. There was positive heterosis for marbling and firmness scores in crosses involving Durocs; however, Hampshire-Yorkshire crosses had negative heterosis for each of these traits. Reciprocal differences between Duroc and Hampshire crosses were small and nonsignificant for all traits. However, most reciprocal differences in crosses involving Yorkshires were significant indicating a difference in the maternal influence of the three breeds