Fertility and growth parameters in a sheep improvement group, for the Corriedale breed in Magallanes

Christian Crempien L.1, Nelson Barría P.2 y Sergio Kusanovié M.3

Four hundred and twenty four ewes, 18 months old and from 13 different ranches, were randomized and bred with 7 rams. These were evaluated for fertility (% lambing ewes), lambing weight, weaning weight and percentage, and average daily gain of the offsprings. The same variables were also analized, according to origen and week of lambing of the ewes. Fertility according to ram, ranged from 57.6 to 80.4%, and in relation to origen of the ewes, from 50.0 to 85.5%; in both cases, there were significant differences (P < 0.05) between the two extremes. The lambing weights of the offsprings of only one ram were lower (P < 0.05) than the resto When lambs of both sexes were analized together, significant differences were observed among the rams' progenies in weaning weight (P < 0.05). The weaning weights adjusted to 90 days were 26.1 and 25.0 kg (males and females). A correlation of 0.93 was found between weaning weights expressed in kilograms and as percentage of the average; also, this last variable showed a correlation of 0.91 with the average daily gain (P < 0.05). Significant differences among weeks of birth, in relation to these three parameters, were observed (P < 0.05). The average daily gain was 250 g; the progeny of ram Nº 3 was statistically lower in this parameter, compared with the progenies of rams Nº 5 and Nº 4. Rams' potential meat production (expressed as percentage of the average), calculated as weaned lambs x weaning weight, differed in 53 points (125.5-72.5) between the extreme cases.

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1 Estación Experimental La Platina (INIA), Casilla 439, Correo 3, Santiago, Chile.
2 Facultad de Ciencias Veterinarias y Pecuarias, U. de Chile, Casilla 1004, Santiago, Chile.
3 Servicio Agrícola y Ganadero, Porvenir, Magallanes, Chile. Actualmente: Corporación de Fomento de la Producción.

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