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A Comparison of Dorset and Finnish Landrace Crossbred Ewes

1984; Oxford University Press; Volume: 59; Issue: 2 Linguagem: Inglês

10.2527/jas1984.592329x

1544-7847

K. P. Cochran, D. R. Notter, F. S. McClaugherty,

Reproductive Physiology in Livestock

Data from 644 exposures and 552 lambings were used to analyze reproductive traits of 1/2-Finnish Landrace, 1/2-Dorset ewes (1/2 Finn); 1/4-Finnish Landrace, 3/4-Dorset ewes (1/4 Finn) and Dorset ewes. Ewes were exposed to Hampshire or Suffolk rams for spring lambing from 1973 to 1978. The analytical model included fixed effects of ewe birth year (EBY), ewe breed (BR), lambing year within EBY and EBY × BR interaction and random effects of ewe within EBY and BR. Conception rate differed (P<.01) for 1/2-Finn (.94), 1/4-Finn (.88) and Dorset (.80) ewes. Litter size was highest (P<.01) for 1/2-Finns (1.97), followed by 1/4-Finns (1.74) and Dorsets (1.44). The 1/2-Finn ewes ranked first for number and weight of lambs weaned, and for number and weight marketed as feeder lambs. Birth weights were heavier (P<.001) for lambs with Dorset dams (3.88 kg) than for lambs with 1/4-Finn (3.24 kg) or 1/2-Finn (3.08 kg) dams. Preweaning average daily gains and adjusted 90-d weights were also larger (P<.001) for lambs with Dorset dams (.26 kg/d and 28.3 kg, respectively) than for lambs with 1/4-Finn (.24 kg/d and 25.4 kg) or 1/2-Finn (.24 kg/d and 25.1 kg) dams. However, Dorset ewes lambed an average of 10.5 d later than Finn-cross ewes, and actual weaning weights (unadjusted for age) did not differ significantly among lambs from Dorset (27.2 kg), 1/4-Finn (26.9 kg) and 1/2-Finn ewes (26.7 kg). Percentage alive at weaning, postweaning average daily gain and average lamb weight at marketing did not differ among breed groups. Repeat ability estimates (t) for reproductive traits were close to zero except for litter size/ewe lambing (t = .14). Significant within-ewe correlations were found between ewe weight and annual conception rate (.29), fleece weight (.12), number of lambs marketed (.24) and weight marketed (.24). No significant between-ewe correlations involving reproductive traits were observed. Average total income/100 ewes lambing was higher for 1/2-Finns ($8,996) than for 1/4-Finns ($8,246) and Dorsets ($7,144).