Causes of low reproductive performance of Bali cattle (Bos sondaicus) in Timor-Leste and strategies to improve reproduction

De Almeida, Alipio (2012). Causes of low reproductive performance of Bali cattle (Bos sondaicus) in Timor-Leste and strategies to improve reproduction MPhil Thesis, School of Agriculture and Food Sciences, The University of Queensland.

       
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Author De Almeida, Alipio
Thesis Title Causes of low reproductive performance of Bali cattle (Bos sondaicus) in Timor-Leste and strategies to improve reproduction
Formatted title
Causes of low reproductive performance of Bali cattle (Bos sondaicus) in Timor-Leste and strategies to improve reproduction
School, Centre or Institute School of Agriculture and Food Sciences
Institution The University of Queensland
Publication date 2012
Thesis type MPhil Thesis
Supervisor Michael D'Occhio
Dianne Mayberry
Total pages 123
Total colour pages 7
Total black and white pages 116
Language eng
Subjects 0702 Animal Production
Formatted abstract
The aims in this thesis were (1) to identify the causes of relatively poor reproductive performance of Bali cattle in Timor-Leste and (2) propose potential strategies to enhance reproductive performance within the economic, resource and environmental constraints in the country. In Study 1, a survey was undertaken to record herd age and gender profiles, the general condition of cattle, and reproductive characteristics across 800 cattle in seven districts. The average body condition score (BCS; scale 1-5) for all cattle surveyed was 3.4 (range 2.5-5.0). Reproductive indices were recorded for 477 females of reproductive age (≥ 20 months). Lactation status was influenced by age and pregnancy was influenced by BCS and lactation. No lactating cows were recorded pregnant. Pregnancy, lactation, and calving rates were 13%, 34% and 35%, respectively. Average age at first calving was 29 months (range 20-40 months) and the average inter-calving interval was 16 months (range 11-40 months). The majority (72%) of calves were born during the dry season and the mortality rate was around 46%. In Study 2, cattle were surveyed in four districts (3 districts were included in Study 1) and an attempt was made to ascertain the prevalence of bovine brucellosis in a sample of 300 females of reproductive age. Brucellosis was detected in 23% of cattle sampled. The average BCS was 3.8 (range 3.0-4.5) and the pregnancy, lactation, and calving rates were 56%, 26% and 54%, respectively. Age at first calving and inter-calving interval were 37 months and 15 months, respectively. Similar to Study 1, 76% of calves were born during the dry season with calf mortality around 33%. There was an apparent difference in pregnancy rate between the two studies suggesting an important influence of yearly differences in the pattern and amount of rainfall on reproduction. The relatively high calf mortality recorded in both studies was likely related, at least in part, to the birth of calves at the start- to mid-dry season when feed is limited and lactating cows would have difficulty in meeting the nutritional requirements of calves. Bali calves are relatively small at birth which probably also contributes to the high mortality relative to other cattle breeds. A potential solution to the relatively high calf mortality is to control the time of mating so that calves are born towards the end of the dry season and early wet season. Only 40% of breeding age females (≥ 20 months) were either pregnant or lactating, indicating that a relatively high proportion of females were not contributing to reproduction. Lactating cows did not re-conceive suggesting that weaning strategies could be implemented to increase herd reproductive performance. Weaning would need to be accompanied by supplementary feeding of calves. The occurrence of brucellosis appears to be a further constraint to reproduction. The management of mating, and hence calving, relative to seasonal cycles of pasture availability, and the control of reproductive diseases, are strategies to improve the reproductive performance of Bali cattle in Timor-Leste.
Keyword Bali Cattle
Reproductive Performance
Brucellosis
Reproduction

 
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Created: Tue, 30 Apr 2013, 18:34:01 EST by Mr Alipio De Almeida on behalf of Scholarly Communication and Digitisation Service