Estimation of Energy Expenditure in Baladi Goats : Genomics and Effects on Productive and Reproductive Capacities in Lebanese Traditional Rearing Systems.
Lebanese mountainous Baladi goats comprise more than 90% of the Lebanese caprine herd and adequate identification of their energy expenditure in traditional rearing systems is essential for the agricultural industry. Despite this high prevalence, their genomic data remains scarce. The objective of this study was to genetically characterize two different goat populations in Lebanon and study their energy expenditure in a traditional rearing system. The study was carried out in Deir El Ahmar, a mountainous region located at 1450m above sea level, and in Boksmaya, a littoral region located at 400m above sea level. The goats were released to graze during the day and then returned to an enclosed farm at night. Genomics consisted of studying a total of 47 does with an average weight of 37.8±2kg, aged between 2- 3 years. Nine quantitative and five qualitative traits were quantified. Following this, 24 goats from each region were divided into 4 groups: 6 does (GI) and 6 bucks (GIII) grazed in order to meet their nutritional requirements, while 6 does (GII) and 6 bucks (GIV) received 250g of barley upon their return from grazing. Travelled distance was measured with a pedometer. Body weight, adaptation parameters, and quantity of milk produced were registered over three different periods depending on the physiological status of the plants: growth, flowering, or senescence. Most prevailing plants ingested by the goats, while grazing, were collected and analysed. Mortality of offspring as well as fertility of semen (volume, mass motility, concentration and abnormalities) were also measured. Results revealed the presence of two main clusters distinguished both genetically and morphologically; the latter can be further divided into 5 subgroups. The mean value of all quantitative traits, except barrel length, showed significant differences between groups (p<0.05): G1 vs. G2 vs. G3 vs. G4 vs. G5; 3.1±0.5 kg vs. 2.6±0.5 kg vs. 2.5±0.4 kg vs. 1.6±0.3 kg vs. 2.3±0.6 kg for milk quantities. Correlation between phenotype and genotype was established; as a matter of fact, a positive correlation was established between milk quantity, ear and head colour as well as the percentage of polymorphism. Average travelled distance fluctuated between 8.6 km and 11.6 km in both regions. Furthermore, in Deir El Ahmar and Boksmaya, there was a significant difference (p<0.05) for body weight between the flowering and senescence periods (42.2±6.2 vs 48.5±8.2 kg). The average daily gain was higher in both groups receiving barley during the spring period (51.4 g/day vs 185.7 g/day). Milk production also showed significant difference (p<0.05) during the senescence period following supplementation: 0.73± 0.2 vs 1.76±.
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