Data on 1474 lactation records obtained from 1972 to 1978 were used to study environmental and genetic influences on production characters in the Damascus goat. Year and month of kidding had a significant effect on 90-and 150-day milk production after weaning, lactation length and litter weight at weaning (P < 0-01), but no influence on litter weight at birth. Milk production after weaning was not related to litter weight at birth or at weaning. Age of goat at kidding had a significant quadratic effect on milk production, and litter weight at birth and at weaning. No such effects were found for lactation length.Estimates of heritability, from paternal half-sib correlations, for 90-and 150-day milk production were similar (0-29 (s.e. 0-14)). The genetic correlation between 90-and 150-day milk yield (0-92 (s.e. 0-03)) was high, indicating that part and whole lactation yields are influenced by the same genes. The phenotypic correlations among milk yield traits and lactation length were also high and positive.

Data on 1542 Damascus kids, collected from 1977 to 1981, were used to study environmental and genetic factors influencing pre-weaning and post-weaning growth traits of kids. Season of birth, type of birth, sex of kid and dam lactation number were the environmental factors investigated. Phenotypic and genetic parameters were estimated from paternal half-sib correlations. The average sire family size was 17·2 kids. Single kids were heavier at birth, at weaning and at 140 days of age than twins or other multiples (P < 0·01). Male kids were heavier (P < 0·01) and grew faster (P < 0·01) than female kids from birth to 140 days of age (4·7 and 4·2 at birth, and 29·2 and 24·6 kg at 140 days, respectively). Dam lactation number significantly affected pre-weaning growth, but had no effect on the post-weaning growth rate of kids.Heritabilities for birth, weaning and 140-day weights, and pre-weaning and post-weaning growth rate, were 0·31 (s.e. 0·08), 0·27 (s.e. 0·07), 0·21 (s.e. 0·07), 0·16 (s.e. 0·06) and 0·22 (s.e. 0·07), respectively. Genetic correlations were mostly high and all positive, especially between weaning weight and 140-day weight (0·82 (s.e. 0·08)), and pre-weaning growth rate and 140-day weight (0·80 (s.e. 0·10)). The corresponding phenotypic correlations were also high and positive (0·71 and 0·67, respectively). No genetic antagonisms were found among the characters studied. Response to selection for post-weaning growth should be effective.

The study examined early measures of growth and their relationships with mature body size. Data on 792 purebred females of the Chios breed, born and reared on two experimental farms between 1978 and 1986, were analysed. Pedigree information and records on live weight at birth, at weaning, 105 days of age and at first and subsequent matings was recorded. There were flock-year differences for all traits studied (P < 0·01) and birth type was important for all traits except post-weaning growth rate. Dam lactation number had no significant effect on birth weight and pre-weaning growth rate, but it significantly affected all subsequent weights and post-weaning growth rate. Estimated heritabilities increased with age and ranged from 0·13 (s.e. 0·14) (birth weight) to 0·30 (s.e. 0·15) (mature weight). Genetic correlations were generally positive between weights and growth traits. Phenotypic correlations were positive and followed the pattern of the genetic correlations. The results suggest that selection for 105-day weight will result in increased mature weight.

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Summary Data from 2600 kidding and 1600 adult lactations, recorded between 1972 and 1978 were utilized to estimate genetic and phenotypic parameters for litter size, litter weight and milk production (after weaning) in the Damascus breed or goat. Data were first corrected for environmental effects using least‐squares constants. Estimates of heritability from daughter‐dam regressions were around zero for litter size and litter weight, whereas those for 90‐day, 150‐day, total milk yield and days in milk after weaning were 0,35 ± 0,08, 0,31 ± 0,08, 0,29 ± 0,08 and 0,16 ± 0,06 respectively. Genetic correlations among part and whole lactation yield were very high indicating that these traits are usually influenced by the same genes. Genetic correlations among reproductive traits could not be estimated because the product of the respective genetic variance components was either zero or negative in most cases. Phenotypic and environmental correlations were moderately high to very high. The implications of the models used and the results obtained for genetic improvement by selection are discussed. Zusammenfassung Genetische und phaenotypische Parameter für einige Fruchtbarkeits‐ und Milchleistungseigenschaften der Damaskusziege Daten von 2600 Geburten und 1600 Laktationen aus den Jahren von 1972 bis 1978 standen zur Verfügung, um genetische und phaenotypische Parameter für die Wurfgröße, das Wurfgewicht und die Milchleistung (nach dem Absetzen) bei der Damaskusziege zu schätzen. Die Daten wurden zunächst nach der Methode der kleinsten Quadrate auf fixe Umwelteffekte korrigiert. Die Schätzungen der Heritabilität aus der Tochter‐Mutter‐Regression waren für die Wurfgröße und das Wurfgewicht nahe Null. Demgegenüber ergaben sich für die 90‐Tage, die 150‐Tage und die Gesamt‐Milchleistung sowie für die Melktage nach dem Absetzen der Lämmer Werte von 0,35 ± 0,08, 0,31 ± 0,08, 0,29 ± 0,08 und 0,16 ± 0,06. Genetische Korrelationen zwischen Teil‐ und Gesamtlaktationsleistungen zeigten sich hoch, während wegen der geringen und zum Teil negativ geschätzten Varianzkomponenten der Reproduktionsmerkmale keine Schätzwerte für die genetischen Korrelationen zwischen Fruchtbarkeits‐ und Milchleistungsmerkmalen ermittelt werden konnten. Die phaenotypischen und umweltbedingten Korrelationen waren hoch bis sehr hoch. Die Anwendung der gewählten varianzanalytischen Modelle und die Ausnutzung der Ergebnisse in züchterischen Entscheidungen wird näher diskutiert. Resumen Parámetros genéticos y fenotípicos de algunas características reproductivas y de producción lechera en cabras de Damasco Datos de 2600 partos y 1600 lactaciones registradas entre 1972 y 1978, fueron utilizados para estimar parámetros genéticos y fenotípicos para el taman̂o de camada, peso de la camada y producción lechera (después del destete) en cabras de Damasco. Los datos fueron previamente corregidos, por los efectos ambientales usando las constantes estimadas de los mínimos cuadrados. Estimaciones de heredabilidad desde la regresión descendenciamadres fueron alrededor ...