Long-term underfed dry, non-pregnant Balady goats can better reduce their energy expenditure than Shami goats
2016
Askar, A R
Twenty-four non-productive females, 12 Balady and 12 Shami goats, were employed to evaluate effects of nutrient restriction on energy expenditure (EE) and energy galance (EB). Animals were individually housed for a 3-month period and then moved to metabolic cages in two sets of 12 animals, three per treatment and breed for each set. Six animals of each breed were fed a concentrate mixture and alfalfa hay diet (1:1 as DM basis) at a level adequate for the metabolizable energy (ME) of maintenance (MEm, C). The other six were fed 50 per cent of this amount relative to actual body weight (R). Energy expenditure was estimated by heart rate (HR) monitor after individual calibration by oxygen consumption with a face mask open-circuit respiratory system. Digestible energy was negatively affected (-10 pts) by restricted feeding, without significant differences between goat breeds. Energy expenditure was greater (P less than 0.001) for C vs R and higher (P less than 0.01) for Shami vs Balady goats. As a result, the EB was similar between both goat breeds fed near maintenance , while it was lesser unbalanced (P less than 0.05) in Balady vs Shami goats when underfed. In conclusion, Balady goats, but not Shami goats, had the ability to reduce their EE in order to improve their EB as a mechanism of adaptation when their ME intake is restricted below MEm requirements for a long time
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