RESUMEN
Correlations between parities for milk yield, fat yield, and days in milk were calculated across and within does for five breeds of United States dairy goats; Alpine, LaMancha, Saanen, and Toggenburg, using lactation records to January 1981. Records were initiated during 1966 through 1979 and had between 125 and 305 d in milk. Parities were first through fourth, and fifth or greater. Overall phenotypic correlations between the three lactation traits averaged across breed were .95 between milk and fat yield and about .60 between milk or fat yield and days in milk. Within-herd phenotypic partial correlations between parities 1 and 2 (the two parities with most data) averaged .47 for milk yield, .42 for fat yield, and .07 for days in milk. Components of variance due to herd averaged about 34% for milk yield and for fat yield and 23% for days in milk. Components of variance due to doe/herd averaged 28% for milk yield, 25% for fat yield, and 17% for days in milk. Repeatabilities averaged .42 for milk yield, .38 for fat yield, and .22 for days in milk.
Asunto(s)
Cabras/fisiología , Lactancia , Paridad , Animales , Femenino , Lípidos/análisis , Leche/análisis , Fenotipo , Embarazo , Factores de TiempoRESUMEN
Data from the University of Illinois dairy herd were used to estimate heritabilities of lactation yield, growth rate, and carcass traits and genetic correlations among them and to evaluate the importance of sire and of interaction of sire with feeding regimen for these traits. Heritabilities for lactation, growth, and carcass traits were small or moderate. Genetic correlations of lactation with carcass traits were moderate negative or large positive. Genetic correlations of estimated average daily gain with lactation and carcass traits could not be estimated. Variance for interaction of sire with feeding was large relative to sire variance for estimated average daily gain. Similarly, variance for interaction of sire with feeding regimen was large for back fat thickness, chilled carcass weight, dressing percentage, maturity score, and yield grade. Interaction of sire with feeding should be considered in genetic studies or in sire evaluation for some carcass traits and average daily gain.
Asunto(s)
Composición Corporal , Peso Corporal , Bovinos/genética , Conducta Alimentaria , Lactancia , Animales , Femenino , Masculino , EmbarazoRESUMEN
The extent of naturally occurring variations of enzyme locus expression was determined for three tissues (liver, muscle, and eye) in two species of sunfish (Centrarchidae), the green sunfish (Lepomis cyanellus) and the redear sunfish (L. microlophus). The genetic basis for species differences in tissue enzyme specific activities of malate dehydrogenase (EC 1.1.1.37), lactate dehydrogenase (EC 1.1.1.27), phosphoglucomutase (EC 2.7.5.1), and glucosephosphate isomerase (EC 5.3.1.9) was investigated by determining enzyme specific activities in the tissues of the reciprocal F1 hybrids and of their backcross progenies. The specific activities for most enzymes in hybrids were intermediate between those of the parental species. Significant differences in enzyme specific activity were detected among the F1 progeny as well as those of backcrosses. Variations in specific activity levels in one tissue were often independent of variations in specific activities in a different tissue. However, the changes in the specific activities of different enzymes within the same tissue were often positively correlated. The tissue glucosephosphate isomerase activity differences appear not to be due to different functional contributions of the glucosephosphate isomerase allelic isozymes. Cluster analysis of distributions of specific activities revealed no simple Mendelian pattern of inheritance for control of tissue enzyme activity. Our results suggest a polygenic control of tissue enzyme specific activity levels.
Asunto(s)
Peces/genética , Glucosa-6-Fosfato Isomerasa/genética , L-Lactato Deshidrogenasa/genética , Malato Deshidrogenasa/genética , Fosfoglucomutasa/genética , Animales , Regulación de la Expresión Génica , Hibridación Genética , Especificidad de la Especie , Distribución TisularRESUMEN
Effects of breed, region, and interaction of breed with region on seasonality of breeding in United States dairy goats were studied. Reproductive performance data were from 76,350 official National Cooperative Dairy Herd Improvement Program records on Alpine, La Mancha, Nubian, Saanen, and Toggenburg does. Variables were month of conception, month of kidding, days open, and deviation of kidding date from March 1. Four northern regions were: 1, greater than or equal to 45 degrees latitude; 2, 40-45 degrees; 3, 35-40 degrees; and 4, less than or equal to 35 degrees. About 20% of Nubians conceived from January through August, whereas only 10% of Alpines and of Toggenburgs conceived during those months. La Manchas conceived most frequently in November whereas other breeds conceived most frequently in October. Each breed kidded most frequently in March. In September and October, 3 to 4% more conceptions occurred in Regions 1 and 2 than in 3 and 4, whereas in November, 7.3% fewer conceptions occurred in Regions 1 and 2 than in 3 and 4. In January, 13.2% of kiddings occurred in Region 4 compared to 5.6% in Region 1. Similarly, during July through December, proportionally more kiddings (11.8%) occurred in Region 4 than in Region 1 (5.2%). In the range of latitudes studied, differences in degree of seasonality due to breed, region, and interaction, although significant, were minor.
Asunto(s)
Cruzamiento , Cabras/fisiología , Reproducción , Estaciones del Año , Animales , Femenino , Estados UnidosRESUMEN
Type appraisal data supplied by United States breed organizations for Ayrshires, Guernseys, Jerseys, and Milking Shorthorns were examined for genetic and environmental sources of variation. Repeatabilities were highest for pelvic angle, udder depth, stature, suspensory ligament, and final score (.51 to .74) and lowest for foot shape (.15 to .29). Variances and covariances were estimated from appraisals from 230 Ayrshire, 352 Guernsey, 699 Jersey, and 51 Milking Shorthorn herds and represented 117, 157, 333, and 32 sires. Herd variances by trait and breed ranged from 2 to 23%. Herd effects were large for stature and rear udder width of Ayrshires, for most traits of Jerseys, and for udder depth of Milking Shorthorns. Herd X sire variance was small but averaged 3% across all breeds and traits. Heritabilities ranged from .06 to .75. Stature had the highest heritability (.34 to .75) for all four breeds. Heritabilities also were high for chest and body (.42), rump width (.36), and pelvic angle (.34) for Guernseys; pelvic angle (.29) and udder depth (.27) for Jerseys; and chest and body (.70), rump width (.50), and final score (.44) for Milking Shorthorns. Foot shape had the lowest heritability for Ayrshires, Guernseys, and Jerseys (.06 to .07). Most of the phenotypic correlations between appraisal traits were low to moderately high. Genetic correlations were calculated.
Asunto(s)
Bovinos/genética , Animales , Biometría , Bovinos/anatomía & histología , Femenino , Variación Genética , Masculino , FenotipoRESUMEN
Statistics for reproduction and lactation traits were estimated from 51,826 records of Alpine, La Mancha, Nubian, Saanen, and Toggenburg does. Means and standard deviations varied little across breed or lactation number. Relationships among reproduction and lactation traits were estimated from a subset of 42,618 records with 125 days or more in milk. Correlations also were stable across breed and lactation number. Regression analysis indicated a curvilinear relationship between lactation traits and reproduction traits.
Asunto(s)
Cabras/fisiología , Lactancia , Reproducción , Animales , Cruzamientos Genéticos , Femenino , Cabras/genética , Leche/metabolismo , Fenotipo , Embarazo , Análisis de RegresiónRESUMEN
Components of phenotypic variation in milk yield from interactions between sires and several feeding and management factors were estimated. Milk yield data were first lactation records. Feeding and management data from Illinois Holstein Dairy Herd Improvement herds were obtained by questionnaires. Sire-herd interaction component was 10% of phenotypic variance in milk yield. Components of variance from interaction between sires and three feeding and management factors, namely, source of roughage for milking herd during summer, amount of grain fed to heifers between 12 and 18 mo age, and amount of grain fed to heifers during 2 mo before calving were negative. Interaction between sires and ideal weight for breeding heifers accounted for 3% of phenotypic variation in milk yield.