Lactational performance in relation to energy intake in the baboon.

The relationship between energy intake and lactational performance in the baboon was investigated by determining energy intake, milk output and energy balance in animals fed ad libitum during a nonreproductive phase and during lactation, or fed 80% or 60% of ad libitum intake during lactation. No evidence was found for an increased efficiency of energy utilization during lactation when feeding was ad libitum, as judged by calculated energy used on activity and maintenance. Restricted feeding did however produce an increase in efficiency, estimated at 17-25%. This change enabled milk output and body nutrient stores to be protected when the restriction was to 80% of the ad libitum intake but at 60% of ad libitum intake, milk output was reduced and body nutrient mobilization was increased. It is proposed that low maternal food intake is associated with impairment of lactational performance when it is also severe enough to increase body nutrient mobilization.