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Dietary fiber is mainly included in the diets for gestating sows to improve gut health and is a regulator of nitrogen balance, which increases the fecal nitrogen excretion while reducing the nitrogen excretion in urine, but the effect of dietary fiber inclusion at different levels of dietary crude protein on the nitrogen utilization and reproductive performance remains uncertain.
Methods: To investigate the effects of dietary fiber, crude protein level, and gestation stage on nitrogen utilization, 28 Landrace-Yorkshire cross gestating sows at parity two were randomly divided into four dietary treatments with seven duplicates of one pig with a repeated-measures design. The diets comprised one with normal crude protein of 13.3%, one with a low crude protein diet of 10.1%, and two diets, one with dietary fiber supplementation of inulin and cellulose at the ratio of 1:1 and one without dietary fiber. Pregnant sows were moved to metabolism cages to measure nitrogen balance. Blood samples were collected, and the litter performance was measured.
Results: The total litter size, litter size alive, and newborn birthweight of piglets did not differ between treatment groups. Sows that received high levels had greater nitrogen output in feces, lower urinary nitrogen, and increased nitrogen retention. Sows that received a low crude protein diet had reduced nitrogen excretion in feces and urine, lower nitrogen retention, and an unchanged nitrogen retention ratio. Sows at the late stage of gestation on days 95 to 98 had lower nitrogen excretion in urine and greater nitrogen retention than in the early stage of gestation on days 35 to 38, associated with a significant decrease in serum amino acids in late gestation. Maternal protein deposition was increased by high dietary fiber, decreased by low crude protein, and lower in late gestation compared with early gestation. Collectively, dietary fiber improved nitrogen utilization by decreasing urine nitrogen output, and nitrogen utilization increased as gestation advanced.
Conclusion: Therefore, high dietary fiber diet can be applied to diets of gestating sows to improve nitrogen utilization, even if they are fed with a low crude protein diet.
Yang M, Hua L, Mao Z, Lin Y, Xu S, Li J, Jiang X, Wu D, Zhuo Y, Huang J. Effects of dietary fiber, crude protein level, and gestation stage on the nitrogen utilization of multiparous gestating sows. Animals. 2022; 12(12): 1543. https://doi.org/10.3390/ani12121543