EFFECT OF PREGNANCY ON BODY COMPOSITION AND ENERGY BALANCE OF THE GILT

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Abstract
In two experiments, each involving 40 gilts, the energy cost of pregnancy was calculated by comparing energy balances between pregnant and nonpregnant animals on the same feed allowance. Treatments comprised an initial slaughter group and pregnant (P) and nonpregnant (NP) groups slaughtered at 56 and 112 days. Separate chemical analyses were carried out on carcass, viscera, liver, blood, uterus and, additionally for each pregnant animal, on fetuses, placenta and uterine fluid. Experiment 1 was conducted during winter and experiment 2 during summer. Differences between P and NP in weights of body components and their chemical composition at 56 and 112 days are presented and discussed. Maintenance cost (energy intake less energy retention) per kg A.75 per day was calculated to be 108 kcal for both pregnant and nonpregnant gilts in summer, and 158 kcal and 153 kcal for pregnant and nonpregnant gilts, respectively, in winter. There was, therefore, no evidence of pregnancy anabolism but rather, a 3% increase in maintenance requirement as a result of pregnancy during the winter experiment.