Farrowing duration is rather long in sows most likely due to selection for large litters, and we hypothesized that prolonged farrowings would compromise sow energy status during farrowing and in turn the farrowing process. Two studies were performed as follows: 1) to evaluate whether sow energy status during farrowing compromise the farrowing kinetics (FK, i.e., farrowing duration and birth intervals) and 2) to study the underlying mechanisms potentially affecting stillbirth rate and farrowing assistance. In study-1, parameters affecting FK were characterized based on data from a total of 166 farrowings from 7 feeding trials focused on sow colostrum production. The data were screened for associations with FK using the CORR procedure of SAS. Traits that were correlated with the FK at P < 0.05 were included in a multivariate regression model. Time since last meal until the onset of farrowing greatly affected the farrowing duration (r = 0.76; n = 166; P < 0.001) and a broken-line model was fitted to describe that relationship. According to the model, farrowing duration was constant (3.8 ± 1.5 h) if the farrowing started before the breakpoint (3.13 ± 0.34 h after the last meal), whereas farrowing duration increased to 9.3 h if the farrowing started 8 h after the last meal. Subsequently, sows were divided into 3 categories based on that trait (≤3, 3 to 6, and >6 h) to evaluate the impact on birth intervals, farrowing assistance, and stillbirth rate. Birth intervals (P < 0.001), odds for farrowing assistance (P < 0.001), and odds for stillbirth (P = 0.02) were low, intermediate, and high when time since last meal was ≤3, 3 to 6, and >6 h, respectively. In study-2, blood samples were collected once or twice each week in late gestation and each hour during farrowing to measure arterial concentrations and uterine extractions of plasma metabolites. Time since last meal was strongly negatively correlated with arterial glucose 1 h after the onset of farrowing (r= -0.96; n = 9; P < 0.001). Glucose appeared to be the key energy metabolite for oxidative metabolism of gravid uterus. In conclusion, the present study strongly suggests that a substantial proportion of sows suffer from low-energy status at the onset farrowing and that this negatively affects the farrowing process. Transferring this knowledge into practice, the results suggest that sows should be fed at least 3 daily meals in late gestation.

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The beneficial effects of dietary fiber (DF) from a behavioral and welfare perspective have been thoroughly studied. However, data on the effects of DF on reproductive performance are scarce. Therefore, the aim of this study was to investigate the impact of increased DF supply during the last 2 wk of gestation on stillbirth rate, preweaning mortality, and total piglet mortality. A total of 644 sows were selected for the experiment from a commercial farm, and the sows were inseminated in weekly batches. Sows in the control group ( = 310) were fed according to the normal feeding strategy of the farm with a gestation diet until 1 wk before expected farrowing, then a transition diet until d 5 of lactation, and then a lactation diet until weaning. Sows in the treatment group ( = 334) were fed as the control group except that 280 g/d of the gestation diet (from d 102 to 108 of gestation) and 570 g/d of the transition diet (from d 109 of gestation until farrowing) was daily replaced with 350 and 700 g/d, respectively, of a DF-rich supplement. Both groups received isocaloric diets on a NE basis. The numbers of live-born and stillborn piglets as well as mortality of live-born piglets with presumed causes of death were recorded. The supplemented DF reduced the proportion of stillborn piglets from 8.8 to 6.6% ( < 0.001) and mortality of total born piglets from 22.3 to 19.9% ( = 0.004) but had no impact on preweaning mortality of the piglets ( = 0.21). Moreover, supplemented DF reduced the proportion of death due to poor viability ( < 0.001; 2.8 vs. 1.5% in the control and treatment groups, respectively) and prevalence of piglet diarrhea ( = 0.004; 0.7 vs. 0.3% in the control and treatment groups, respectively). Crushing, low birth weight, and poor viability were the top 3 contributors to preweaning mortality of live-born piglets, in descending order. In conclusion, the supplemented DF reduced the proportion of stillborn piglets and total piglet mortality as well as mortality due to poor viability and piglet diarrhea in lactation.

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Arginine is the precursor for the synthesis of nitric oxide and may increase mammary plasma flow (MPF), which may in turn increase mammary nutrient uptake. Quantifying mammary nutrient uptake improves our understanding of mammary nutrient metabolism and may potentially allow identification of limiting nutrients for colostrum and milk production. Thus, the objectives of the present study were 1) to study the impact of 25 g/d of crystalline Arg (ARG) on MPF and uptake of nutrients by the mammary glands compared with an isonitrogenous supply of Ala (51 g/d; control [CON]) fed to a total of 8 sows from d 30 of gestation until weaning on d 28 of lactation and 2) to quantify mammary nutrient uptake in late gestation and in early and at peak lactation. Sows were surgically fitted with indwelling catheters on d 76 ± 2 SEM of gestation. -amino hippuric acid (AH) was infused (3.0 mmol/h) in the infusion catheter inserted in the mammary vein, initiated 1 h before the first blood sample at -10, -3, 3, and 17 d in milk (DIM). Blood samples were simultaneously drawn from catheters inserted in the femoral artery and the mammary vein, and the samples were collected in hourly intervals from 0.5 h before to 6.5 h after feeding. Sow milk production was assessed at 3 and 17 DIM. Arterial plasma concentrations of Arg and Ala were increased in ARG and CON sows, respectively ( < 0.01), whereas we did not succeed in detecting a greater MPF in ARG sows ( = 0.30). Arterial-venous differences ( = 0.03) and net mammary flux ( = 0.01) of Ala were increased in CON sows, while the net flux of most other metabolites ( > 0.05) was unaffected by treatment. The mammary extraction of all essential AA was below 13% in late gestation. The average mammary extraction of essential AA at peak lactation was greatest for Leu (51%), while the preprandial extraction was greatest for Lys (57%). The mammary carbon balance (input-output) was negative (-39 ± 12 mol C/d) in early lactation but almost balanced at peak lactation (-13 ± 14 mol C/d), suggesting that mammary fat depots contributed to milk synthesis. In conclusion, we failed to observe an increased MPF and mammary uptake of AA and energy metabolites in ARG-supplemented sows. The mammary extraction rate of essential AA indicated that AA were not limiting for the mammary glands in late gestation, while Lys and Leu appeared to be the 2 most limiting essential AA for milk production at peak lactation.

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This study aimed to determine the optimal supply of lactation feed during the transition period to minimize farrowing duration and maximize colostrum yield and quality with the overall aim of reducing piglet mortality. A total of 48 sows were stratified for body weight and assigned to six levels of feed supply (1.8, 2.4, 3.1, 3.7, 4.3, and 5.0 kg/d) from day 108 of gestation until 24 h after the onset of farrowing. The number of total born, live born and stillborn piglets, birth time and birth weight of each piglet, and frequency of farrowing assistance were recorded and blood samples were obtained from newborn piglets at birth. Live born piglets were further weighed at 12 and 24 h after birth to record weight gain, which in turn was used to estimate intake and yield of colostrum. Colostrum samples were collected at 0, 12, 24, and 36 h after onset of farrowing. Farrowing duration was shortest (4.2 h) at intermediate (3.7 kg/d), longest (7.1 to 7.6 h) at low (1.8 and 2.4 kg/d), and intermediate (5.6 to 5.7 h) at high (4.3 and 5.0 kg/d) feed intake (P = 0.004; mean comparison). Farrowing assistance was lowest (0.7-0.8%) at intermediate feed intake (3.7 and 4.3 kg/d) and substantially elevated (4.3-4.7%) at both lower and higher feed intake (P = 0.01; mean comparison). The cubic contrast revealed 4.1 kg/d as the optimal feed intake to achieve the shortest farrowing duration and to minimize farrowing assistance. Newborn piglets from second-parity sows were less vital than piglets from gilts as evaluated by blood biochemical variables immediately after birth. Colostrum yield was greatest at 3.1 kg/d (P = 0.04), whereas the cubic contrast revealed 3.0 kg/d as the optimal feed intake to maximize colostrum yield. Concentrations of colostral components were affected by the diet, parity, and their interaction except for lactose concentrations. In conclusion, the study demonstrated the importance of proper feed level during the transition period on sow productivity. Moreover, this study estimated 4.1 and 3.0 kg/d as the optimal feed intake during the transition period to improve farrowing characteristic and colostrum yield, respectively, and these two feed intake levels supplied daily 38.8 MJ ME and 23.9 g SID lysine (3.0 kg/d) or 53.0 MJ ME and 32.7 g SID lysine (4.1 kg/d). The discrepancy of optimal feed intake for optimal farrowing and colostrum performance suggest that it may be advantageous to lower dietary lysine concentration in the diet fed pre-partum.