[Show abstract][Hide abstract] ABSTRACT: The study was based on a set of 256 records for milk yield at 305 days, 1,899 records of test day yield, and 466 growth records collected at Al Jouf center from 1987 to 2009. Except season of calving, milk yield at 305 days was affected by parity and calving year, whereas test day yield was influenced by parity, calving year, stage of lactation, and test milk day. Only birth year had a significant effect on all growth traits, whereas dam's parity influenced weights at birth and 3 months, and birth season affected birth weight, weight at 6 months and average daily gain (ADG) 3-6 months. Variance components estimated using an animal model showed that heritability and repeatability estimates for milk yield at 305 days were 0.24 and 0.28, respectively. The corresponding estimates for test day yield were 0.22 and 0.66, respectively. Direct heritabilities were 0.37, 0.50, 0.60, and 0.85 for body weights at birth, 3, 6, and 12 months of age, respectively, and 0.25, 0.37, 0.49, and 0.29 for ADG 0-3, 3-6, 6-12, and 0-12 months, respectively. The annual genetic progress was 0.05 kg for milk yield at 305 days and 0.0003 kg for test day yield. Annual genetic gains during 23 years were 0.050, -0.185, 0.079, and 0.331 kg for body weights, respectively, and -9, -5, -4, and -13 g, for ADG, respectively. It was concluded that it is necessary to set up a field milk and growth recording system in order to collect a large number of records to check these estimates.
Full-text · Article · Dec 2010 · Tropical Animal Health and Production
[Show abstract][Hide abstract] ABSTRACT: Reproductive traits and calving weight were assessed in Saudi camels, and non-genetic factors influencing them were studied using data collected at Al Jouf centre from 1987 to 2009. Age at first conception, age at first calving, open period, calving interval, gestation length and weight at calving of camels averaged 42.3 months, 54.8 months, 10.6 months, 22.6 months, 377.5 days and 591.9 kg, respectively. A mixed model including the camel as a random effect was used to assess the effect of environmental effects on the traits studied. Age at first conception and age at first calving were affected by camel's birth year. Open period and calving interval were not affected by parity or year of calving. However, camels that calved from October to February had a calving interval of 2.5 months higher than those that calved from March to September. Gestation length was affected by season and year of calving but not by parity or sex of calf. Camels calving from March to September had a gestation length 6.6 days shorter than those calving from October to February. Weight at calving was affected by parity and year of calving but not by season of calving. It was concluded that an improvement in camel reproductive traits is possible both through improving management systems and utilisation of controlled breeding techniques.
Full-text · Article · Mar 2010 · Tropical Animal Health and Production