Fat thickness fluctuations during the three-year study. Part A: Experimental variation of average of feed intake in WF, R and V groups expressed in Horse Feed Unit (UFC) contained in the commercial or dehydrated alfalfa pellets. Part B: Fat thickness fluctuations (means ± S.E.M), in WF, R and V groups during the three-year study under natural photoperiod conditions. The WF and R groups received a diet supplying approximately 100% and 50% of energy requirements for maintenance, respectively. The V group was fed in order to mimic variations of energy availability in natural grasslands, but about 4-5 months in advance of phase relative to the beginning of natural availability of grass in pastures. The arrows indicate the date when the blood samples were collected each hour during two 24 h periods.