POSTPARTUM HYPOPHAGIA IN PRIMIPAROUS SOWS .1. EFFECTS OF GESTATION FEEDING LEVEL ON FEED-INTAKE, FEEDING-BEHAVIOR, AND PLASMA METABOLITE CONCENTRATIONS DURING LACTATION

To investigate the relationship between feeding level during gestation and voluntary feed intake, feeding behavior, and plasma metabolite le vels during lactation, 18 crossbred, primiparous sows were assigned to two dietary treatments. From d 60 of gestation until farrowing, sows were fed either a standard level of feed (SL; 1.85 kg/d) or were allow ed ad libitum (AL) access to feed. During 28-d lactation all sows were allowed ad libitum access to feed. Eight SL and seven AL sows complet ed the experiment. Feed intake was measured daily during the final 40 d of gestation and throughout lactation. On d 105 of gestation and d 1 , 7, 14, and 21 of lactation, feeding behavior was observed and blood samples were collected via indwelling catheters. Plasma was analyzed f or nonesterified fatty acids (NEFA), insulin, glucose, and alpha-amino N. During gestation AL sows ate more feed than did SL sows. This incr eased intake was balanced by reduced feed intake during lactation, whe n AL sows ate less than SL sows (P < .001). The AL sows gained more we ight during gestation (P < .001) and lost more weight during lactation (P < .005) than did the SL sows. Feed intake and weight change during gestation and lactation combined were not different between treatment s (P = .85). During lactation, the AL sows ate fewer meals (P < .05) o f a similar size than did the SL sows. During lactation, the area unde r the curve formed by plasma NEFA concentration was greater (P = .06) and that for insulin was less (P < .01) in AL than in SL sows. Plasma glucose and alpha-amino N were not affected by gestation feeding level . Increased insulin secretion in SL sows may have increased hunger by reducing the mobilization of NEFA and by increasing peripheral glucose utilization.