Genética

Título: Incidence of skin spots and pigmentation in corriedale sheep
Autores: Kremer, R.; Urioste, J-I.; Naya, H.; Rosés, L. y López, C.
Publicación: World Congress Animal Production, Porto Alegre, Brasil. October 26-31. CD. 2003.

Resumen

The occurrence of black/brown fibers in wool from Corriedale sheep is recognized as a fault which reduces its value (15 - 18 %) when the number exceeds 300 fibers/kg tops. In Uruguayan wool it is of 5000 fibers/kg top, most of them from environmental origin (faeces and urine dyeing). With appropriated clip preparation, it diminishes to 800-1000 fibers, remaining those from a genetic source. Skin spots with black/brown fibers and isolated pigmented fibers are the probable origin of these fibers.

The objective of this study was to quantify the incidence of skin spots in wool bearing area of Corriedale sheep, as well as pigmentation score of the mouth and spotting in the face as a way to identify correlated characters. On two Corriedale flocks (n = 764), at shearing, a close inspection was performed to identify spot presence, number, area (mm2 determined with a caliper), location (dorsal vs. side) and score (1 to 5 - according to estimated percentage of black/brown fibers in the spot). Simultaneously, a pigmentation score (1 to 5) of mouth was assigned and spotting (number and area) of face was determined.

On average, 70.8 % of the sheep presented skin spots, in these animals the median of the number of spots/sheep was 4, with a total area of 179 mm2. Of all spots detected (n = 3500), 73.5 % had a score of 1 (up to 20 % of black/brown fibers). Pigmentation in the mouth and percentage of spotting in the face was higher (P<0.01) in spotted sheep.

Título: Evaluation of corriedale and F1 with east friesian and texel on grazing conditions
Autores: Barbato, G.; Kremer, R.; Rista, L.; Sienra, I.; Rosés, L.; Neimaur, K. y Neirotti V.
Publicación: World Congress Animal Production, Porto Alegre, Brasil. October 26-31. Cd. 2003.

Resumen

A study was made to evaluate the effect of maternal breed on: reproductive traits (fertility, fecundity and lambs survival ), wool production, lamb growth and carcass yield of lambs. The essay was made during 2 years, the ewes were Corriedale (C) (n= 75), F1 Texel x Corriedale (F1T) (n=98) and F1 East Friesian x Corriedale (F1EF) (n=91). The mating, with Hampshire Down rams, was in march/april, the lambing in august/september, shearing in october and the slaughter of all lambs at 32 kg. liveweight in december. The ewes and their lambs were running on implanted pastures (clover/festuca) all year around.

Fertility was higher in F1T than C or F1EF (P ? 0.01); fecundity was higher in F1EF than the others genotypes (P ? 0.01); lamb survival at 72 h was similar among breeds. Lamb marked/ewes mated was 92.6% in F1EF, 83.2% in F1T and 64.7% in C (P ? 0.01). Average daily gain of lambs from birth to 32 kg, was higher (P ? 0.01) in F1T (0.241 kg/d) and F1EF (0.241 kg/d) than in C (0.221 kg/d). Lamb carcass yield (%) was higher inF1T (46.2) and F1EF (45.7) than in C (43.3) (P ? 0.01). No differences among genotypes were found in GR, carcass measurements. In ewes, average greasy wool wight was 4.11±0.73 kg with no breed effect, but here was a breed effect (P ? 0.01) on wool yield and diameter.

Título: Effect of sire breed (Corriedale, southdown, hampshire, suffolk, texel and east friesian), year, sex and weight on carcass composition of lams
Autores: Kremer, R.; Barbato, G.; Castro, L.; Rista, L.; Rosés, L.; Herrera, V. y Neirotti, V.
Publicación: Small Ruminant Research. 2004

Resumen

Carcass composition of 314 lambs from 300 Corriedale ewes sired by Corriedale, Southdown, Hampshire Down, Suffolk, Texel and East Friesian rams and born in two years were evaluated. Wether and female lambs (110 to 194 d of age) were slaughtered within a body weight range of 20 to 51 kg . The experiment was designed to group carcasses corresponding to commercial targets, light (8.0-12.9 kg), medium (13.0-16.9 kg) and heavy (17.0-23.5 kg). Dressing percentage and fat depth over the 12th rib (GR) were determined. The carcasses were cut to obtain a double hind pistol cut and ribs off without flank. The hindhalves were boned out into five commercial joints (loin, steak, chump, leg and shank), also total saleable meat yield (SMY), separable fat (SF) and bone of the hindhalves were recorded. Moisture, ether extract and crude protein were determined in the steak. Year and sex had significant effect on several carcass measures. Effect of sex was significant for dressing percentage, GR, bone , separable fat, SMY:bone and SMY:SF ratios. Effect of carcass weight group was significant for age at slaughter, dressing percentage, GR, DHP, boned cuts, SMY, bone, fat, SMY:bone and SMY:SF ratios. Sire breed had significant influence on age at slaughter, dressing percentage, GR, DHP, boned cuts, SMY, bone, fat, SMY:bone and SMY:SF ratios. Sire breed had an influence of 3.5 units on dressing percentage, carcass weight group of 2.6 units, year 1.9 units and sex 0.47 units. The proportion of SMY in the double hind pistol showed a 6.1 % difference (P < 0.01) between the highest (East Friesian) and the lowest (Corriedale) value. The East Friesian had the highest ratios of SMY:bone (2.06) and SMY:SF (6.22), whereas in Texel these values were 1.99 and 5.52, respectively. The remaining breeds had significantly lower values ranging from 1.87 to 1.93 (SMY:bone ratio) and 4.80 to 5.24 (SMY:SF ratio). In heavy carcasses the percentage of lambs with a GR higher than 15 mm (overfat) were: Southdown 57 %, Suffolk 46 %, Texel 46 %, Corriedale 36 %, Hampshire 21 % and East Friesian 0 %.

Título: Dairy milk yield of east friesian and corriedale sheep
Autores: Kremer, R.; Barbato, G.; Rosés, L. y Rista, L.
Publicación: World Congress Animal Production, Porto Alegre, Brasil. October 26-31. CD. 2003.

Resumen

Sheep dairy industry is a non-traditional production in Uruguay. East Friesian and their crosses with non-dairy breeds is the main breed milked. The objective of this study was to evaluate dairy milk yield at farm level of East Friesian crosses. In one year, four populations were evaluated (about 1000 ewes). In all flocks, the ewes were running on pastures (native and/or implanted) with no significant supplementary feed. The sheep were mated in march, after parturition, they reared a lamb during 30 to 60 d (10 - 15 kg) and after weaning the ewes were milked twice daily by machine. The following data were collected for each sheep: breed (F1, East Friesian X Corriedale, n = 332; F2, East Friesian X F1, n = 387 and Corriedale, n = 93), number of milking (first or higher), age (estimated by number of teeth), milk produced during milking only period by monthly recording (CICPE, A4), and body condition (1 to 5). Dairy milk production corrected to 100 d was of 53.12+22.60 l, the main significant effects (P<0.01) were farm, breed and number of milking. F1 produced 54.9 % more than Corriedale (P<0.01) and F2 produced 67.6 % more than Corriedale (P<0.01). Ewes milked for first time, yielded 34.7 % less than milked for second time or higher (P<0.01). Age was non significant on milk yield. Average body condition during the milking period was 1.96 + 0.47, it was affected (P<0.01) by farm, breed and number of lactation.

Título: Parámetros genéticos y fenotípicos en corriedale
Autores: Kremer, R.
Publicación: Anales de Facultad de Veterinaria. 65-76. 1981-1983.

Resumen

Se llevaron registros durante 10 años de distintos parámetros genéticos y fenotípicos en una majada de 500 Corriedale mantenidos en pasturas naturales. Se encontró que la edad influyó sobre el peso del vellón sucio (PVS), peso vivo (PV) y tasa reproductiva (TR). El pico de mayor producción fue a los 3 años para PVS, 7 ½ años para PV y 5-6 años para TR. Las ovejas que destetaron un cordero, produjeron 10,7% menos PVS (P<0,01) que las falladas. La repetibilidad promedio del PVS a lo largo de la vida de 4 generaciones de ovejas fue de 0,56. Se estudiaron las correlaciones fenotípicas entre las características de la lana, encontrándose valores estadísticamente significativos para (PV/PVS,

PV/peso de vellón limpio (PVL), PVS/PVL, PVS/diámetro (D), PVL/rinde (R), PVL/D, R/rizos por pulgada (RPP) y D/RPP.

Título: Heredabilidad y repetibilidad del grado de lana en la cara en corriedale
Autores: Kremer, R.; Barbato, G. y Perdigón, F.
Publicación: Seminario Científico Técnico Regional de Lanas. 132-134. 1985.

Resumen

Corriedale sheep in Uruguay has a high incidence of face cover score, associated with an increase of labour costs, the negative correlation with economic important characteristics. There are few references about heritability of face cover score in Corriedale, to calculate them was the aim of this paper. The study was carried out in a Corriedale flock (500 ewes) during 1984 and 1985. A diagramatic standard ranging from 2 to 9 was used to score face cover score in the ewes before mating, one year later, in weaned lambs and when they were one year old. Repeatability from weaning to one year of age was 0.606+0.055; in adult ewes between years 0.774+0.065. Average heretability at weaning time was 0.569+0.311 and at one year of age 0.423+0.313.