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Abstract
Two experiments were conducted to determine the effects of 5, 10 or 20 ppm total dietary manganese (Mn) on sow productivity. In the first experiment, sixty-six crossbred gilts received the three dietary treatments beginning on d 92 of the first parity gestation and continuing through the end of the third lactation. Average birth weight of pigs increased (P $<$.08) as the dietary Mn level increased. Litter size was not affected by dietary treatment (P $>$.60). Backfat thickness of the sows on d 109 of gestation and d 21 of lactation increased (P =.08) as the level of Mn increased in the diet. Milk Mn concentrations increased (P $<$.001) as the dietary Mn level increased, but decreased over time for sows within each treatment (P $<$.001). Primiparous sows fed the 20 ppm Mn diet tended to exhibit an earlier estrus than those fed the other levels of Mn (P =.20). In the second experiment, sows from the 5 and 20 ppm Mn treatments (nine sows/treatment) were bred for a fourth parity to determine the effect of dietary Mn on the physiology and productivity of sows. There was no difference between treatments in the number of pigs born or weaned (P $>$.80). Birth weight of pigs from sows fed 20 ppm Mn was greater (P $<$.01) than from sows fed 5 ppm. However, there was no treatment difference in pig weaning weight at 21 d of age (P =.99). Total serum cholesterol concentrations were greater at d 60 (P =.06) and d 90 (P $<$.01) of gestation for sows consuming 20 ppm Mn compared to 5 ppm, with no differences at other times throughout gestation or lactation (P $>$.10). Milk Mn concentrations were greater on d 1 (P =.04) and d 14 (P $<$.001) of lactation for sows fed 20 ppm Mn than for those fed 5 ppm. Liver and rib Mn concentrations were higher in sows consuming 20 ppm Mn than for those fed 5 ppm (P =.02). Dietary Mn level affects birth weight and lipid metabolism, and may play a role in the early onset of estrus in primiparous sows.
