The aim of the present study was to determine the optimal concentration of dietary protein required in transition diets for multiparous sows that enhance the farrowing process, colostrum production, and subsequent lactation performance. Forty-eight multiparous sows were allotted to one of six dietary treatments according to body weight (290 ± 3 kg) and parity (3.8 ± 0.2) from day 108 of gestation until 24 h after the onset of farrowing. The diets were isoenergetic and contained increasing concentrations of dietary protein (expressed as standardized ileal digestible [SID] Lys) and were supplied at a daily feed supply of 3.8 kg. On day 108 of gestation and days 2, 7, 14, 21, and 28 of lactation, body weight, and back fat thickness were recorded, and blood was sampled on day 108 of gestation, at the onset of farrowing, and days 3, 10, 17, and 24 of lactation from the sows for analysis of plasma metabolites. On day 115 of gestation, urine, and feces were collected for nitrogen (N) balance. The number of liveborn and stillborn piglets and time of birth were recorded and blood from every fourth piglet was sampled at birth for blood gas analysis. Piglets were weighed individually from birth until weaning, to estimate the colostrum and milk yield of the sows. Colostrum and milk samples were collected, and their compositions were determined. On days 3 and 28 of lactation, sows were injected with deuterium oxide to estimate body composition. The N utilization was maximized when the concentration of SID Lys in the transition diet was 6.06 g/kg (P < 0.01). When urinary concentrations of urea were expressed relative to creatinine, the relative concentration of urea remained low until a dietary concentration of 6.08 g SID Lys/kg, above which the relative concentration of urea increased (P < 0.01). Stillbirth rate increased linearly with increasing SID Lys concentration in the transition diet (P < 0.001), thus the concentration of SID Lys should be kept as low as possible without impairing sow performance excessively. A carry-over effect on milk yield was observed, showing that a dietary SID Lys concentration of 5.79 g/kg during transition optimized milk production at an average yield of 13.5 kg/d (P = 0.04). Increasing loss of body fat in lactation was observed with increasing SID Lys concentration in the transition diet (P = 0.03). In conclusion, the transition diet of multiparous sows should contain 5.79 g SID Lys/kg when fed 3.8 kg/d (13.0 MJ ME/kg), for a total SID Lys intake of 22 g/d.
Keywords: Colostrum; dietary protein; lysine; milk yield; sow nutrition; transition period.
In late gestation, the protein requirement of sows increases rapidly due to growth of the fetuses and mammary glands, whereas their energy requirement only is slightly increasing. Recent studies show that a feed supply of 4.1 kg/d in the last week of gestation is beneficial for the farrowing process and subsequent lactation performance. However, studies on feed supply cannot separate the effects of dietary fractions, so the sows’ requirement for protein in the transition period remain unclear. The aim of the present study was to determine the dietary protein requirement of multiparous sows using a dose–response design with six diets containing increasing dietary protein (expressed as standardized ileal digestible [SID] Lys) from 3.99 to 8.57 g SID Lys/kg at a feeding level of 3.8 kg/d. Results indicate that the utilization of nitrogen (protein) during the transition period was maximized when the diet contained 6.06 g SID Lys/kg. Colostrum yield was unaffected by dietary treatment while dietary SID Lys in transition diet was found to have a carry-over effect on milk yield in the subsequent lactation period that was optimized at 5.79 g SID Lys/kg. As the concentration of SID Lys in the transition diet increased, stillbirth rate also increased, therefore, the concentration of SID Lys should be kept as low as possible without impairing sow performance excessively. In conclusion, the transition diet of multiparous sows should contain 5.79 g SID Lys/kg when fed 3.8 kg/d (13.0 MJ ME/kg), for a total SID Lys intake of 22 g/d.
© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science.