No abstract

Ninety-six yearling Hereford heifers (mean = 232 +/- 3 kg) were stratified on the basis of weight and then allotted randomly within weight groups into 16 pens of six each. Treatments were Hei-Gro (deviced or nondeviced; HG), Synovex-H (implanted or nonimplanted) and location in the feedlot relative to steers (isolated or nonisolated) imposed in a 2 x 2 x 2 factorial design with two replicates. During the growing phase, estrous activity was monitored by weekly rectal palpation of the reproductive tract of three heifers from each pen. Incidence of standing estrus, as determined by daily visual observation, was recorded for the first 21 d of the finishing phase. Heifers implanted with Synovex showed higher (p less than .05) average daily gains and final shrunk weights than nonimplanted heifers during the growing phase. Synovex also resulted in increased (P less than .05) weight gain during the finishing phase and produced heavier (P less than .05) hot carcass weights. HG did not significantly (p less than .05) affect any performance traits reported. Synovex or HG treatments had no effect on estrous activity of the heifers. Location significantly (P = .05) affected estrous activity during the finishing phase. HG caused reproductive tract scarring and infection (P less than .01). Heifers treated with the HG + Synovex combination had more severe (P less than .05) infection than those treated with HG alone. Heifers not isolated from steers had larger (P less than .05) ovaries than isolated heifers, although no difference (P less than .05) was found in ovarian weight.

Production data from 681 yearling ewes were evaluated for the effect of ewe breed and management system on fertility, prolificacy, lamb birth weight, lamb survival, lamb weaning weight, ewe fleece weight, and total lamb weight weaned per ewe exposed. Two hundred seven straightbred Targhee (T) and 474 1/4 Finn-1/4 Dorset-1/2 Targhee (FDT) crossbred ewes managed in a range or farm flock system were included in this study. Ewes were born in 1984 through 1987 and lambed the first time as 2-yr-olds. The basic model included main effects of ewe breed and management system. Lamb sex was added to the model for birth and weaning weight analysis. The FDT ewes had higher (P < .05) fertility (95.3 vs 91.3%) and (P < .01) prolificacy (1.93 vs 1.45 lambs) than the T ewes. Targhee ewes had heavier (P < .01) lambs at birth (5.2 vs 4.0 kg) and weaning (26.1 vs 23.4 kg, P < .01) and produced more (P < .01) wool (3.8 vs 3.2 kg). Lamb survival was not different (P > .10) between the breeds or management systems. Although FDT lambs were lighter at weaning, FDT ewes weaned 5.8 kg more (P < .01) total lamb weight per ewe exposed than did the T ewes (34.7 vs 28.9 kg), because FDT weaned more (P < .01) lambs per ewe exposed (1.46 vs 1.09 lambs). Farm flock ewes were more prolific (1.73 vs 1.64 lambs, P < .05) and had heavier lamb birth weight (4.8 vs 4.4 kg, P < .01) than range flock ewes.(ABSTRACT TRUNCATED AT 250 WORDS)