The effect of long term under- and over-feeding on milk and plasma fatty acids profile and on insulin and leptin concentrations of goats

Effects of long term under- and over-feeding on goats' milk chemical composition and fatty acid (FA) profile, on blood plasma insulin and on leptin concentrations were determined. Lactating goats were divided into three sub-groups and fed the same ration in quantities covering 70% (under-feeding), 100% (control) and 130% (over-feeding) of their energy and crude protein requirements. Chemical composition of milk, blood plasma FA profile and insulin plasma concentrations were affected by long term under- and over-feeding. With regard to milk FA profile, under-feeding reduced the concentrations of C-16:0 and long chain FAs and increased that of C-18:0 and polyunsaturated FA in milk fat compared with controls. Over-feeding increased the cis9, trans11 C-18:2 milk fat content compared with the control and increased the medium chain FAs compared with under-feeding. Lean goats responded differently to under- and over-feeding in terms of leptin level changes, possibly due to their low fat stores. (C) 2011 Elsevier Ltd. All rights reserved.