RESUMEN

The response to three generations of selection for incidence of degenerative myopathy of the Musculus supracoracoideus (DMS) in meat-type chickens was studied. From each of two genetic bases named E and F, which were derived from two commercial broiler stocks, a high incidence, low incidence, and a nonselected control strain were initiated. Selection of breeders to produce Generations 1 and 2 was based on the incidence of DMS in their parents after induced wing exercise; mass selection for plasma creatine kinase levels after induced wing exercise was used to produce Generation 3. Little genetic progress in selection occurred in Generations 1 and 2. There was a response in Generation 3, especially in Base E selected for low incidence. Heritability of incidence of DMS was estimated to be .48. Body weights at 8 weeks of age, 18 weeks of age, and breast angle at 18 weeks of age of Generation 3 were greater (P less than .05) for affected than nonaffected birds and positively correlated phenotypically with incidence of DMS. Genetic correlations were extremely variable. The higher incidence of DMS in birds with desirable traits suggests that the breeder must use a multitrait selection program to reduce incidence of DMS as well as improve production traits.

Asunto(s)

RESUMEN

The incidence of degenerative myopathy of the Musculus supracoracoideus (DMS) was calculated in 23 strains comprising 1868 meat-type chickens. Twenty strains were commercial parent stocks and three strains were experimental strains from Ottawa similar to commercial broiler stocks of some 15 to 20 years ago. In the commercial strains DMS incidence ranged from 0 to 43% in males and 0 to 22% in females at ages ranging from 49 to 68 weeks. The three experimental strains did not have DMS. Data from strains with DMS were analyzed for associations between DMS and each of a number of body size and egg production traits. The DMS-positive birds had a larger breast angle (P less than .05) measured at 6 weeks of age (93 vs. 89 degrees) and a larger body weight (P less than .01) at 52 weeks (3748 vs 3594 g) than DMS-free birds. No significant relationships with other body size or egg production traits were detected.

Asunto(s)

Asunto(s)

RESUMEN

The response to five generations of selection for high and low plasma cholesterol levels was examined in two lines of Single Comb White Leghorn chickens derived from the same population. An unselected control line was also maintained. Juvenile cholesterol levels of blood plasma were measured in 24,754 birds during the experiment. Males at 9 to 10 weeks of age had higher plasma cholesterol levels than females of the same age. Estimates of the heritability of plasma cholesterol level for males and females from the sire and dam components of variance in unselected population, ranged from .19 to .30. Realized heritabilities from the selected lines were lower and ranged from .14 to .19 with no significant differences between lines or sexes. Differences between the two selected lines in the fifth generation were 37 mg% for males and 33 mg % for females. High cholesterol levels were associated with high mortality. The estimated genetic correlation between plasma cholesterol and egg production was negative. After five generations of selection for plasma cholesterol, yolk cholesterol was 108 mg % lower in the low selected line than in the controls, but there was little difference between the high selected line and controls in this trait.

Asunto(s)

RESUMEN

1. Diagnosis for degenerative myopathy of the Musculus supracoracoideus (DMS) in the live bird was attempted from plasma creatine kinase (CK) [EC 2.7.3.2] activities in 70 female turkeys. The blood of each bird was sampled 18 to 20 times over an age span of 16 to 79 weeks. 2. DMS incidence was 15.7%. 3. After CK values were logarithmically transformed and corrected for bleeding date, 82% of the affected birds had one CK value that deviated 3 or more standard deviations from the mean of other values for the same bird. The results indicate that plasma CK activities can be used to identify affected birds with a high degree of reliability.

Asunto(s)

RESUMEN

Turkeys were fed either corn based or wheat based rations and necropsied between 28 and 118 weeks of age. Practically all birds affected with degenerative myopathy were detected among those killed between 77 and 85 weeks of age. The incidence of the disease was 0% among 125 males and 7.9% among 139 females. No significant difference in incidence was observed between birds fed corn based and birds fed wheat based rations.

Asunto(s)

RESUMEN

Blood cell lysates of chickens and turkeys were subjected to starch gel electrophoresis and the gels were stained for adenosine deaminase. Two zones were observed singly or together in the electrophoretic patterns of each lysate. Zones of chicken lysates were analogous in electrophoretic mobility to those of turkeys. An extra zone which appeared in patterns of a sample stored over one month was not detected in patterns of a second aliquot of stored sample treated with a reducing agent prior to electrophoresis. Family data involving 110 chicken progeny and 221 turkey progeny supported the hypothesis that these zones were controlled by two codominant alleles designated ADAA and ADAB. In the two Leghorn strains studied ADAB was much more frequent than ADAA, but the frequency distribution was reversed in the Small White turkey strain examined.

Asunto(s)

RESUMEN

A group of hens laying high specific gravity eggs and a group laying low specific gravity eggs were selected from each of 6 Single Comb White Leghorn strains and compared for possible qualitative differences in carbonic anhydrase (CA) isozymes in blood and oviducal tissues. Starch gel electrophoretic patterns of erythrocytes, blood plasma and oviducal tissues of magnum, isthmus and uterus from 173 selected hens disclosed 9 carbonic anhydrase isozymes. In oviducal tissues 5 isozyme zones were routinely observed in gel patterns. Of these zones, the 2 with the slowest migration rate had differing staining intensity depending upon the section of the oviduct examined. Five zones were also observed in patterns of lysed erythrocytes, 4 of them possessing the same electrophoretic mobility as 4 to 5 observed in the oviducal tissues, and 1 zone that was observed only in the erythrocytes. Plasma patterns of hens with active ovaries possessed 2 zones, 1 always and 1 occasionally present in patterns of oviducal tissues. Plasma patterns of hens with inactive ovaries possessed 1 or 2 additional unique CA zones. No qualitative differences were found in enzyme patterns between birds laying high specific gravity eggs and those laying low specific gravity eggs.

Asunto(s)

Asunto(s)