A two-diet feeding regime for lactating sows reduced nutrient deficiency in early lactation and improved milk yield

Ad libitum feeding systems for lactating sows: effects on productivity and welfare of sows and piglets

The nutritional requirements of sows change during lactation and thus require adapted and dynamic feeding regimes that consider the sows' behavioral needs and production traits. The present study evaluated the effect of four different feeding systems on productivity and aspects of the welfare of 61 sows and their piglets during lactation. A non-ad libitum system (CON) was compared with two computer-monitored (COMP, COMP + ) ad libitum feeding systems, that allowed sows to access feed via displacement of an electronic sensor, as well as a third purely mechanical ad libitum feeding system (MECH). Daily feed disappearance, piglet growth, piglet growth per feed disappearance as well as sows' weight and conception rate were recorded. Health indicators of sows and piglets were scored as well as sow behavior analyzed for a total of 96 hours/sow from video recordings taken on days 2-4 and 23 postfarrowing (n = 35 sows). Sows from all three ad libitum systems (COMP, COMP+, MECH) showed a lower feed disappearance than CON (P < 0.01). Additionally, average daily piglet growth tended to be higher (P = 0.05) and piglet growth per sow feed disappearance was significantly higher in all three ad libitum systems than in CON (P < 0.01). Piglet mortality, sow weight loss and subsequent conception rates did not differ between treatment groups. Piglets in COMP and COMP + had fewer head lesions (P = 0.01). Sows in all three ad libitum systems spent more time with their head in the trough than in the non-ad libitum system (P < 0.01). Occurrence of sow stereotypies (vacuum chewing, biting fixtures) was rare (typically < 2% of scans) and did not differ between treatments. Our data suggest that sows fed ad libitum eat what they need and can convert feed more efficiently into the piglets' growth without additional weight loss. Furthermore, the increased time sows spent in ad libitum systems with their head in the trough points toward longer feeding times, which might be beneficial in terms of meeting pigs' behavioral need to forage. Taken together, our initial studies on sow feeding behavior and feed efficiency will benefit the development of new lactation feeding systems that promise to improve animal welfare and productivity while reducing feed costs.

The standardized ileal digestible lysine-to-net energy ratio in the diets of sows to optimize milk nitrogen retention is dynamic during lactation

Fifty-two multiparous sows (average parity 3.1 ± 0.9 and initial BW 245.6 ± 32.5 kg) were used to evaluate the effects of dietary standardized ileal digestible (SID) Lys-to-net energy (NE) ratios on nitrogen (N) utilization throughout a 24-d lactation period. Sows were randomly assigned to one of five isoenergetic feeding programs that provided equally spaced and increasing SID Lys-to-NE ratios between 2.79 and 5.50 g SID Lys/Mcal NE. The feeding programs were generated by blending the two extreme diets in varying proportions and were provided to sows immediately after farrowing (day 1) and until weaning at day 24 ± 1. Nitrogen balances were conducted between days 4 and 7, 12 and 15, and 20 and 23 ± 1 of lactation to represent weeks 1, 2, and 3, respectively, using total urine collection and fecal grab sampling. Contrast statements were used to determine the linear and quadratic effects of increasing Lys-to-NE ratios. Linear and quadratic broken-line and polynomial quadratic (QPM) models were used to determine the optimum dietary Lys-to-NE ratios for N retention in milk. The Bayesian information criterion was used to assess the best fit. Feeding program did not influence sow average daily feed intake (5.8 ± 0.1 kg), BW change (-8.2 ± 3.1 kg), or change in back fat thickness (-2.6 ± 0.7 mm) over the 24-d lactation period, but piglet average daily gain increased with dietary SID Lys-to-NE ratio (linear; P < 0.05). Sow N intake increased with increasing dietary Lys-to-NE ratio in weeks 2 and 3 (linear; P < 0.001). Whole-body N retention (N intake - N output in urine and feces) increased with increasing dietary Lys-to-NE ratio in all weeks (linear; P < 0.05). The N retention in milk tended to increase then decrease with increasing dietary Lys-to-NE ratio in weeks 1 and 2 (quadratic; P = 0.051 and P = 0.081) and the QPM showed optimal milk N retention at 4.28, 4.42, and 4.67 g Lys/Mcal NE for weeks 1, 2, and 3, respectively. Maternal N retention (N intake - N output in urine, feces, and milk) decreased and then increased in week 1 (quadratic; P < 0.01) and increased in weeks 2 and 3 (linear; P < 0.01) with increasing dietary Lys-to-NE ratio. Therefore, the SID Lys-to-NE ratio necessary to optimize milk N output is dynamic throughout lactation. A two-diet feeding program could be created to match optimal weekly or daily SID Lys-to-NE ratios, which could lead to improved piglet ADG and body weights at weaning.

Feeding the modern sow to sustain high productivity

Selection for hyper-prolific sows has increased the litter size by more than 50% during the last three decades, and proper nutrition of the female pigs has concomitantly changed due to improved prolificacy and productivity of gilts and sows. This review summarizes the physiological characteristics and nutritional challenges associated with feeding modern hyper-prolific sows during the gilt rearing period and during gestation, transition, and lactation periods. The review presents up-to-date knowledge of the energy and lysine requirements of female pigs and focuses on how nutrition may increase fat gain and limit protein and weight gain in the gilt rearing period and in early and mid-gestation. In late gestation, fetal and mammary growth should be considered and during the transition, colostrum yield and farrowing performance need to be optimized. Finally, milk production should be optimized and body mobilization should be minimized in the lactation period to achieve high feed efficiency in hyper-prolific sows.

Characteristics of sows' milk and piglet nutrient utilization during a 28-d lactation period

The present study aimed to characterize the performance of suckling piglets from high prolific sows and investigate the impact of milk composition on piglet growth during a 4-wk lactation period. Piglet performance included weight gain (WG), milk intake, nutrients and energy in milk, and piglet energy metabolism in weeks 1 to 4 of lactation. Data from six previous experiments were used with a total of 2,047 piglets and 604 milk samples collected from 151 sows. Piglet body weight linearly increased (P < 0.001) as lactation progressed, with the piglet WG being low in week 1 (132 g/d) and relatively constant from weeks 2 to 4 (248 g/d; P < 0.001). The metabolizable energy (ME) intake of the piglets increased (P < 0.001) from weeks 1 to 3; however, with lower values in week 4 than for week 3. The heat energy production and energy required for maintenance (MEm) linearly increased (P < 0.001) from weeks 1 to 4. In addition, the retained energy and ME to MEm ratio only increased from weeks 1 to 2 (P < 0.001) and then declined through week 4. Pearson correlation coefficients were used to examine the relations between the milk nutrient composition and the WG in weeks 1 to 4. The results showed that WG was negatively correlated with the milk protein concentration at all stages of lactation (P < 0.001). In contrast, the WG was positively correlated with milk fat and lactose concentrations in weeks 2 and 4, respectively (P < 0.001). In conclusion, the stage of lactation influenced WG, milk intake, nutrients in milk, energy in milk, and the energy metabolism of the suckling piglets. Moreover, maximizing milk protein concentration does not optimize piglet growth.

Effect of a multicarbohydrase containing α-galactosidase in sow lactating diets with varying energy density

Sow productivity improvements are associated with high energetic demand due to increasing prolificity. The reproductive life and longevity of sows, and the readiness for weaning of the offspring may be impaired when sows loose significant body weight (BW) during lactation. The impact of a multicarbohydrase containing α-galactosidase on a low energy dense lactation diet was evaluated in this study. Two-hundred and eight sows (208 ± 25.2 kg) were blocked by parity and BW to one of four treatments, in which a corn-soybean meal diet was formulated to have varying levels of added fat (0, 1.5%, and 3%) to titrate an energy density model. A fourth treatment replicated the 0% added fat formulation with enzyme supplementation at 250 g/tonne. Sows were weighed individually on entry, post-farrow (by calculation) and at weaning. Daily feed intakes (ADFI) and caloric intake were used for calculation of sow feed efficiency (FE) and caloric efficiency. Litter performance was characterized at birth, and size was standardized within 24h of farrow and within treatment to ensure uniform litter sizes. Average wean weight and pre-weaning mortality were determined. Piglets were weighted individually to study litter weight distribution. Data was analyzed as a randomized completely block design, using sow as the experimental unit, treatment as the main effect, and standardized average weight and litter sizes as covariates where appropriate. Although sows fed a multicarbohydrase had lower standardized litter size (P < 0.001), average wean weight was higher in this group and equivalent to the 3% added fat treatment. Enzyme supplementation tended to reduce the proportion of light weight pigs (BW < 4.1kg) within the litter, when compared with the 0% added fat diet (P < 0.1). The multicarbohydrase tended to increased sow ADFI (P < 0.10), although sows from all treatments had equivalent caloric intakes during lactation (P > 0.1). Enzyme supplementation yielded significant improvements in sow FE (P < 0.01), similar to the 3% added fat group. Thus, the carbohydrase degrading enzyme tested in this study improved the efficiency of sows, while increasing average wean weights of the offspring, suggesting an improvement in nutrient digestion and/or metabolic efficiency from typical lactation diets.

Precision feeding of lactating sows: implementation and evaluation of a decision support system in farm conditions

Precision feeding (PF) aims to provide the right amount of nutrients at the right time for each animal. Lactating sows generally receive the same diet, which either results in insufficient supply and body reserve mobilization, or excessive supply and high nutrient excretion. With the help of online measuring devices, computational methods, and smart feeders, we introduced the first PF decision support system (DSS) for lactating sows. Precision (PRE) and conventional (STD) feeding strategies were compared in commercial conditions. Every day each PRE sow received a tailored ration that had been computed by the DSS. This ration was obtained by blending a diet with a high AA and mineral content (13.00 g/kg SID Lys, 4.50 g/kg digestible P) and a diet low in AAs and minerals (6.50 g/kg SID Lys, 2.90 g/kg digestible P). All STD sows received a conventional diet (10.08 g/kg SID Lys, 3.78 g/kg digestible P). Before the trial, the DSS was fitted to farm performance for the prediction of piglet average daily gain (PADG) and sow daily feed intake (DFI), with data from 1,691 and 3,712 lactations, respectively. Sow and litter performance were analyzed for the effect of feeding strategy with ANOVA, with results considered statistically significant when P < 0.05. The experiment involved 239 PRE and 240 STD sows. DFI was similarly high in both treatments (PRE: 6.59, STD: 6.45 kg/d; P = 0.11). Litter growth was high (PRE: 2.96, STD: 3.06 kg/d), although it decreased slightly by about 3% in PRE compared to STD treatments (P < 0.05). Sow body weight loss was low, although it was slightly higher in PRE sows (7.7 vs. 2.1 kg, P < 0.001), which might be due to insufficient AA supply in some sows. Weaning to estrus interval (5.6 d) did not differ. In PRE sows SID Lys intake (PRE: 7.7, STD: 10.0 g/kg; P < 0.001) and digestible P intake (PRE: 3.2, STD: 3.8 g/kg; P < 0.001) declined by 23% and 14%, respectively, and feed cost decreased by 12%. For PRE sows, excretion of N and P decreased by 28% and 42%, respectively. According to these results, PF appears to be a very promising strategy for lactating sows.

Increased feeding frequency prior to farrowing: effects on sow performance

Reducing the interval between the consumption of the last meal and the start of farrowing is suggested to increase the energy available to sows during farrowing, potentially reducing the farrowing duration and easing piglet births. The present study aimed to examine whether increasing feeding frequency from one to two feeds within standard production hours (0700 to 1500 hours) would produce a difference in farrowing duration and/or stillborn numbers. From entry to farrowing crates (110 ± 1 d gestation) to farrowing (116 ± 1 d gestation), multiparous sows (n = 118) were fed a daily fixed amount of feed either once at 0800 hours or in two meals at 0800 and 1300 hours. Sow weights and backfat depths were recorded on entry and exit from the farrowing crate. Litter size and weight were recorded 24 h after farrowing and on day 21 of lactation. Sows fed twice had a shorter farrowing duration and fewer stillborn piglets than those fed once (2.21 ± 0.56 h vs. 3.25 ± 0.52 h; P = 0.001). The interaction between treatment and farrowing duration showed that sows fed twice have a reduced farrowing duration and had significantly lower stillborn rates than those fed once or those fed twice with longer farrowing durations (P < 0.001). These findings suggest that increasing feeding frequency prior to farrow can reduce the farrowing duration and stillborn numbers in some sows, however, some sows remain with a high stillborn rate regardless of feeding frequency. Piglet average daily gain was greater in once-fed sows, but fewer of these sows remained in the herd at subsequent farrowing. Further, subsequent total born and born alive were higher in twice-fed sows. Feeding sows at a higher frequency can improve farrowing performance in some sows and could increase the longevity of the sow in the herd.

Effect of increasing dietary energy density during late gestation and lactation on sow performance, piglet vitality, and lifetime growth of offspring

Genetic selection for hyperprolificacy in sows has resulted in a significant increase in the number of piglets born alive per litter but subsequently, decreased piglet vitality and growth. As a consequence, increasing sows' energy intake during lactation to help increase piglet vitality and growth is increasingly important. The objective of this study was to investigate the effect of increasing dietary energy density for lactating sows on weight and back-fat changes in sows, milk composition, and vitality and growth of progeny. Gestating sows (N = 100; Large White × Landrace) were randomly assigned to one of four energy dense diets at day 108 of gestation until subsequent service; 13.8 (LL), 14.5 (L), 15.2 (H), and 15.9 MJ DE/kg (HH). All diets contained 1.2% total lysine. Blood samples from sows were taken on day 108 of gestation and at weaning (day 26 of lactation) and colostrum (day 0) and milk samples (day 14) were collected during lactation. Sow lactation feed intakes were recorded daily. The number of piglets born per litter (total and live), piglet birth weight (total and live), intrauterine growth restriction (IUGR) traits and muscle tone were recorded in piglets at birth. Piglet tympanic ear temperature (TEMP) was recorded at birth and at 24 h. Pigs were weighed on days 1, 6, 14, 26, 33, 40, 54, 75, and 141 of life. Postweaning (PW) pigs were fed standard cereal-based diets. Pig carcass data were collected at slaughter (day 141). Lactation energy intake was higher for HH sows than for all other treatments (P < 0.01). Colostrum and milk composition and lactation feed intake were not affected by treatment. The number of piglets born per litter (total and live) and piglet birthweight (total and live) was similar between treatments. Piglets from LL sows had more IUGR traits (P < 0.01), while those from HH sows had better muscle tone (P < 0.01) than all other treatments. Piglets from LL sows (P < 0.01) and piglets from H sows (P < 0.01) had a higher 24 h TEMP than piglets from HH sows. H sows weaned a greater number of piglets than L sows (P < 0.05) and HH sows (P < 0.01), while L sows weaned lighter litters than H (P < 0.05) and LL sows (P < 0.05). Pig growth PW was unaffected by treatment. High energy dense diets increased energy intake in sows, without depressing appetite. Feeding an HH diet improved piglet muscle tone at birth, whereas feeding an H diet increased litter size at weaning. Inconsistent results were observed for other traits of piglet vitality and for preweaning litter growth performance.

Reduced protein diet with near ideal amino acid profile improves energy efficiency and mitigate heat production associated with lactation in sows

Background

The study objective was to test the hypothesis that 1) lowering dietary crude protein (CP) increases dietary energetic efficiency and reduces metabolic heat associated with lactation, and 2) excessive dietary leucine (Leu) supplementation in a low CP diet decreases dietary energetic efficiency and increases metabolic heat associated with lactation.

Methods

Fifty-four lactating multiparous Yorkshire sows were allotted to 1 of 3 isocaloric diets (10.80 MJ/kg net energy): 1) control (CON; 18.75% CP), 2) reduced CP with a near ideal or optimal AA profile (OPT; 13.75% CP) and 3) diet OPT with excessive Leu (OPTLEU; 14.25% CP). Sow body weight and backfat were recorded on day 1 and 21 of lactation and piglets were weighed on day 1, 4, 8, 14, 18, and 21 of lactation. Energy balance was measured on sows during early (day 4 to 8) and peak (day 14 to18) lactation, and milk was sampled on day 8 and 18.

Results

Over 21-day lactation, sows fed OPT lost body weight and body lipid (P < 0.05). In peak lactation, sows fed OPT had higher milk energy output (P < 0.05) than CON. Sows fed OPTLEU tended (P = 0.07) to have less milk energy output than OPT and did not differ from CON. Maternal energy retention was lower (P < 0.05) in OPT and OPTLEU compared to CON sows, and did not differ between OPTLEU and OPT sows. Sows fed OPT had higher (P < 0.05) apparent energy efficiency for milk production compared to CON. Heat production associated with lactation was lower (P < 0.05) or tended to be lower (P = 0.082), respectively, in OPT and OPTLEU compared to CON sows.

Conclusion

The OPT diet, in peak lactation, improved dietary energy utilization for lactation due to less urinary energy and metabolic heat loss, and triggered dietary energy deposition into milk at the expense of maternal lipid mobilization. Leucine supplementation above requirement may reduce dietary energy utilization for lactation by decreasing the energy partitioning towards milk, partially explaining the effectiveness of OPT diet over CON diets.

The Effect of Dietary Oil Type and Energy Intake in Lactating Sows on the Fatty Acid Profile of Colostrum and Milk, and Piglet Growth to Weaning

This study investigated the effect of salmon oil in lactating sow diets and offering these diets in a phased dietary regimen to increase the energy density of the diet in late lactation. Sow and piglet productivity to weaning, the fatty acid profile of milk, piglet blood and tissues at weaning were the main parameters measured. Multiparous sows (n = 100) (Landrace × Large White) were offered dietary treatments from day 105 of gestation until weaning. Dietary treatments (2 × 2 factorial) included oil type (soya or salmon oil) and dietary regimen (Flat 14.5 MJ/kg DE diet offered until weaning or Phased 14.5 MJ/kg DE diet offered to day 14 of lactation then a second diet containing 15.5 MJ/kg DE offered from day 15 until weaning). Salmon oil inclusion increased the total proportion of n-3 fatty acids in colostrum (p < 0.001), milk (p < 0.001), piglet plasma (p < 0.01), adipose (p < 0.001), liver (p < 0.001) and muscle (p < 0.001). Increasing sow dietary energy level in late lactation increased the total n-3 fatty acids in milk (p < 0.001), piglet adipose (p < 0.01) and piglet muscle (p < 0.05). However, piglet growth to weaning did not improve.

Optimal crude protein in diets supplemented with crystalline amino acids fed to high-yielding lactating sows1

The objective of the current study was to determine the requirement of standardized ileal digestible (SID) CP for maximal litter gain in high-yielding lactating sows due to insufficient supply of either His, Leu, Val, Ile, or Phe. The content of SID Lys was formulated at 95% of the recommended level, while that of Met, Met+Cys, Thr, and Trp was formulated at 100% of the recommended level or slightly greater using crystalline AA. A total of 540 parity 1 to 5 sows (L×Y, DanBred, Herlev, Denmark) were included in the study from day 3 after farrowing until weaning at day 26. Sows were allocated to six dietary treatments increasing in SID CP content (96, 110, 119, 128, 137, and 152 g/kg). Litters were standardized to 14 piglets at day 3 ± 2 after farrowing. At day 3 ± 2 after farrowing and at day 26 ± 3, sow BW and back fat, and litter weight were recorded. On a subsample of 72 sows (parity 2 to 4), litters were also weighed at days 10 and 17 ± 3, and milk and blood were sampled at day 3 ± 2 d, and 10, 17 and at 24 ± 3 d in lactation. Sow body pools of protein and fat were determined on the 72 sows at days 3 ± 2 and 26 ± 3 d using the D2O dilution technique. All data were subjected to ANOVA, and to linear and quadratic polynomial contrasts. Variables with quadratic effects or days in milk × treatment interactions were analyzed using linear regression or one-slope linear broken line using the NLMIXED procedure of SAS. Average daily litter gain reached a breakpoint at 125 g SID CP/kg (as-fed). Multiparous sows had a greater litter gain than primiparous sows (3.33 vs. 3.02 kg/d above the breakpoint; P < 0.001) but litter size (13.1 ± 0.1) at weaning were unaffected by dietary treatment (P = 0.62). Sow BW loss was minimized at 102 g SID CP/kg. Concentrations of protein and casein in milk increased linearly with increasing SID CP (P < 0.001). Milk urea reached a minimum at 111-118 g SID CP/kg (P < 0.05) and milk fat a maximum at 116 g SID CP/kg (P < 0.05). In conclusion, 125 g SID CP/kg feed was required to maximize litter gain.

Nitrogen utilization of lactating sows fed increasing dietary protein1

The objectives of the study were 1) to quantify dietary N utilized for milk N and N loss in urine and feces, in sows fed increasing dietary CP with a constant amount of Lys, Met, Thr, and Trp to meet their standardized ileal digestible (SID) requirement and 2) to determine the optimal dietary CP concentration based on dietary N utilization for milk production. Seventy-two sows were fed 1 of 6 dietary treatments, formulated to increase the SID CP as followed: 11.8, 12.8, 13.4, 14.0, 14.7, and 15.6% and formulated to be isocaloric (9.8 MJ NE/kg). Diets were fed from day 2 after parturition until weaning at day 28 (± 3 d). Litters were equalized to 14 piglets and weighed within 48 h following parturition. Sows were weighed and back fat scanned, at day 18 (± 3 d) and day 28 (weaning; ± 3 d). Litter weight was recorded at day 11, 18 (± 3 d), and 28 (± 3 d). Nitrogen balances were conducted on approximately day 4, 11, and 18 (± 3 d). Daily milk yield was estimated from recorded litter gain and litter size. To calculate sows mobilization of fat and protein, body pools of fat and protein were estimated by D2O (deuterated water) enrichment on day 4 and 18 (± 3 d). No linear, quadratic, or cubic effects of increasing dietary CP was observed for sows total feed intake, sow BW, body pools of protein and fat, protein and fat mobilization, total milk yield, and piglet performance. The protein content in milk increased linearly with increasing dietary CP in week 1 (P < 0.05), week 2 (P < 0.05), and week 3 (P < 0.001). Urine production did not differ among treatments and N output in urine increased linearly with increasing dietary CP concentration in week 1 (P = 0.05), week 2 (P < 0.001), and week 3 (P < 0.001). Urine N excretion relative to N intake increased linearly with increasing dietary CP (P < 0.001). Milk N utilization relative to N intake decreased linearly from 77.8% to 63.1% from treatment 1 through 6 (P < 0.001). Corrected milk N utilization decreased from 68.6% to 64.2% from treatment 1 through 6 (P < 0.05). In conclusion, a low dietary CP concentration for lactating sows with supplemented crystalline AA improved the efficiency of dietary N utilization and reduced the N output in urine without affecting lactation performance.

Increased dietary protein for lactating sows affects body composition, blood metabolites and milk production

Hyper-prolific sows nurse more piglets than less productive sows, putting a high demand on the nutrient supply for milk production. In addition, the high production level can increase mobilization from body tissues. The effect of increased dietary protein (104, 113, 121, 129, 139 and 150 g standardized ileal digestible (SID) CP/kg) on sow body composition, milk production and plasma metabolite concentrations was investigated from litter standardization (day 2) until weaning (day 24). Sow body composition was determined using the deuterium oxide dilution technique on days 3 and 24 postpartum. Blood samples were collected weekly, and milk samples were obtained on days 3, 10 and 17 of lactation. Litter average daily gain (ADG) peaked at 135 g SID CP/kg (P < 0.001). Sow BW and back fat loss reached a breakpoint at 143 and 127 g SID CP/kg (P < 0.001). Milk fat increased linearly with increasing dietary SID CP (P < 0.05), and milk lactose decreased until a breakpoint at 124 g SID CP/kg and 5.3% (P < 0.001) on day 17. The concentration of milk protein on day 17 increased until a breakpoint at 136 g SID CP/kg (5.0%; P < 0.001). The loss of body protein from day 3 until weaning decreased with increased dietary SID CP until it reached a breakpoint at 128 g SID CP/kg (P < 0.001). The body ash loss declined linearly with increasing dietary SID CP (P < 0.01), and the change in body fat was unaffected by dietary treatment (P=0.41). In early lactation (day 3 + day 10), plasma urea N (PUN) increased linearly after the breakpoint at 139 g SID CP/kg at a concentration of 3.8 mmol/l, and in late lactation (day 17 + day 24), PUN increased linearly after a breakpoint at 133 g SID CP/kg (P < 0.001) at a concentration of 4.5 mmol/l. In conclusion, the SID CP requirement for sows was estimated to 135 g/kg based on litter ADG, and this was supported by the breakpoints of other response variables within the interval 124 to 143 g/kg.

Review: Nutrient requirements of the modern high-producing lactating sow, with an emphasis on amino acid requirements

Sow productivity improvements continue to increase metabolic demands during lactation. During the peripartum period, energy requirements increase by 60%, and amino acid needs increase by 150%. As litter size has increased, research on peripartum sows has focused on increasing birth weight, shortening farrowing duration to reduce stillbirths and improving colostrum composition and yield. Dietary fibre can provide short-chain fatty acids to serve as an energy source for the uterus prior to farrowing; however, fat and glucose appear to be the main energy sources used by the uterus during farrowing. Colostrum immunoglobulin G concentration can be improved by increasing energy and amino acid availability prior to farrowing; however, the influence of nutrient intake on colostrum yield is unequivocal. As sows transition to the lactation period, nutrient requirements increase with milk production demands to support large, fast-growing litters. The adoption of automated feed delivery systems has increased feed supply and intake of lactating sows; however, sows still cannot consume enough feed to meet energy and amino acid requirements during lactation. Thus, sows typically catabolise body fat and protein to meet the needs for milk production. The addition of energy sources to lactation diets increases energy intake and energy output in milk, leading to a reduction in BW loss and an improvement in litter growth rate. The supply of dietary amino acids and CP close to the requirements improves milk protein output and reduces muscle protein mobilisation. The amino acid requirements of lactating sows are variable as a consequence of the dynamic body tissue mobilisation during lactation; however, lysine (Lys) is consistently the first-limiting amino acid. A regression equation using published data on Lys requirement of lactating sows predicted a requirement of 27 g/day of digestible Lys intake for each 1 kg of litter growth, and 13 g/day of Lys mobilisation from body protein reserves. Increases in dietary amino acids reduce protein catabolism, which historically leads to improvements in subsequent reproductive performance. Although the connection between lactation catabolism and subsequent reproduction remains a dogma, recent literature with high-producing sows is not as clear on this response. Many practical aspects of meeting the nutrient requirements of lactating sows have not changed. Sows with large litters should approach farrowing without excess fat reserves (e.g. <18 mm backfat thickness), be fed ad libitum from farrowing to weaning, be housed in a thermoneutral environment and have their skin wetted to remove excess heat when exposed to high temperatures.

Effect of dietary protein intake on energy utilization and feed efficiency of lactating sows

The objective of the current study was to quantify loss of energy in feces, urine, heat, and milk, to evaluate feed efficiency and to evaluate optimal ratio of dietary CP to energy for lactating sows fed increasing dietary CP. A total of 72 sows were included in the experiment from day 2 after parturition until weaning at day 28. Sows were allocated to 6 dietary treatments formulated to be isocaloric (9.8 MJ NE/kg) and increasing standardized ileal digestible (SID) CP (11.8, 12.8, 13.4, 14.0, 14.7, and 15.6% SID CP). Sows were weighed and back fat scanned within 2 d after farrowing, at days 18 ± 3 and 28 ± 3. Litters were standardized to 14 piglets within 2 d after farrowing and weighed at day 1 or 2 and at days 11, 18, and 28 (within ± 3 d). Feed intake (feed supply minus residue) was registered, and milk, urine, and fecal samples were collected at days 4, 11, and 18 (within ± 3 d). Sow milk yield was estimated from litter gain and litter size, and sow heat production was calculated factorially. On days 4 and 18 (±3 d), sows were enriched with D2O (deuterated water) to estimate body protein and fat pool size. Overall, sow BW loss, back fat loss, fat and protein mobilization, litter size, and piglet performance were not affected by diets, except for sows fed treatment 5, which had lower ADFI and lower milk production, and a tendency to lower piglet ADG compared with the remaining treatment groups (P < 0.01, P = 0.03, P =0.08, respectively). Relative to GE intake, the energy excreted in urine increased from 3.3% to 5.3% (P < 0.001), whereas energy lost as heat increased numerically from 54.5% to 59.0% with increasing dietary CP. The feed efficiency as evaluated by NE corrected for body mobilization peaked when sows were fed at their requirement (treatment 2; 12.8% SID CP; P = 0.01), whereas the feed efficiency was 1% lower for treatment 1, whereas it was 3% to 6% lower for treatments 3 through 6. In conclusion, energy loss in urine and likely also energy lost as heat increase if the dietary protein to energy ratio is unbalanced, and evaluating feed efficiency of lactating sows by correcting for body mobilization seems to be a promising approach to improve sow feeding in the future.

Dietary protein reduction improves the energetic and amino acid efficiency in lactating sows

Strategies to mitigate the environmental impact of swine production are essential to contribute to the sustainability of the swine industry. Our work has focussed on the area of dietary crude-protein (CP) reduction with crystalline amino acid (CAA) supplementation to create diets containing a near ‘ideal’ amino acid (AA) balance, and to assess the environmental impact of feeding these diets to lactating sows. Additionally, with an increasing availability of CAA at competitive costs relative to feed-ingredient proteins, precise prediction of requirements of the less traditionally limiting AA such as histidine, isoleucine, leucine, phenylalanine and valine are ever more relevant. Prediction of AA requirements using modelling approaches is dependent on accurate estimates of AA efficiency of utilisation for milk-protein production. Aggressive reduction in dietary CP and CAA supplementation to improve dietary AA balance minimises urea-nitrogen (N) synthesis, N excretion and ammonia emission, without compromising lactation performance. Improving dietary AA balance increases energy, global N and AA efficiency of utilisation for milk production, and, in some cases, increases true milk protein and casein yield in peak lactation. The mechanisms by which enhanced AA balance improves nutrient efficiency include potentially increased extraction rate of AA by the mammary gland and reduced heat production. Individual AA efficiencies are dynamic, and, thus, estimating their maximum biological efficiency value (MBEV) is of critical importance for accurate prediction of AA requirements. We have estimated MBEV for each individual AA. Future dietary formulations using reduced CP diets to minimise N excretion and ammonia emission will require AA requirements based on MBEV estimates.

Whole-body nitrogen utilization and tissue protein and casein synthesis in lactating primiparous sows fed low- and high-protein diets

Twenty-eight lactating Yorkshire and Yorkshire × Landrace primiparous sows were used to test the hypothesis that feeding a diet with reduced CP concentration and supplemented with crystalline AA (CAA) does not decrease milk protein yield and litter growth but improves apparent N utilization for milk protein production. Sows were assigned to 1 of 2 dietary treatments: 1) control (CON; 16.2% CP; analyzed content) or 2) low CP with CAA to meet estimated requirements of limiting AA (LCP; 12.7% CP) over a 17-d lactation period. A N balance was conducted for each sow between days 13 and 17 of lactation. On day 17, a 12-h primed continuous infusion of l-[ring-2H5]-Phe was conducted on 12 sows (n = 6) with serial blood and milk sampling to determine plasma AA concentrations and Phe enrichment, and milk casein synthesis, respectively. Thereafter, sows were sacrificed and tissues were collected to determine tissue protein fractional synthesis rates (FSR). Litter growth rate and milk composition did not differ. Sows fed the LCP diet had reduced N intake (122.7 vs. 153.2 g/d; P < 0.001) and maternal N retention (13.5 vs. 24.6 g/d; P < 0.05) and greater apparent efficiency of using dietary N intake for milk production (85.1% vs. 67.5%; P < 0.001). On day 17 of lactation, all plasma essential AA concentrations exhibited a quartic relationship over time relative to consumption of a meal, where peaks occurred at approximately 1- and 4-h postprandial (P < 0.05). Protein FSR in liver, LM, gastrocnemius muscle, mammary gland, and in milk caseins did not differ between treatments. Feeding primiparous sows with a diet containing 12.7% CP and supplemented with CAA to meet the limiting AA requirements did not reduce milk protein yield or piglet growth rate and increased the apparent utilization of dietary N, Arg, Leu, Phe+Tyr, and Trp for milk protein production. The improved apparent utilization of N and AA appears to be related exclusively to a reduction in N and AA intake.

Impact of sow energy status during farrowing on farrowing kinetics, frequency of stillborn piglets, and farrowing assistance

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.

Does feeding frequency during lactation affect sows' body condition, reproduction and production performance?

The present study investigated whether a three-times compared to two-times feeding frequency during lactation affects sows' body condition, reproductive performance as well as growth performance of the piglets . In a commercial farm, eight groups (8-10 animals) with a total number of 68 sows were included in the study. During lactation, four groups received feed two times (treatment 2DF) and four groups three times daily (treatment 3DF). Within treatments, sows were classified into young (<2 parities) and old (≥3 parities). Body condition score (BCS), shoulder lesions, return to estrus rate and piglet's growth performance were recorded. The 3DF sows had a higher (p < 0.05) feed intake and less shoulder lesions (p < 0.05) than 2DF animals. Return to estrus rate in the 3DF treatment was 0% for young and 29% for old sows. In the 2DF treatment return to estrus rate was 20% for young and 5% for old sows. In conclusion, three-times versus two-times daily feeding frequency during lactation increased feed intake and had a positive effect on sows' BCS and the frequency of shoulder lesions, while it also reduced incidents of return to estrus rate in young sows.

Impact of diet deprivation and subsequent overallowance during gestation on lactation performance of primiparous sows

The impact of diet deprivation followed by overallowance during gestation on metabolic status of pregnant gilts and their lactation performance was determined. Gilts were fed a standard diet until day 27 of gestation and were subsequently reared under a control (CTL; n = 28) or an experimental (treatment, TRT; n = 26) dietary regimen. The experimental regimen provided 70% (restriction diet, RES) and 115% (overallowance diet, OVER) of the protein and NE contents provided by the CTL diet. The RES diet was given from days 28 to 74 of gestation followed by the OVER diet from day 75 until farrowing. Blood samples were obtained from all gilts on days 28, 75, and 110 of gestation, and on days 3 and 20 of lactation to measure concentrations of IGF-1, urea, FFA, and glucose. Milk samples were collected from 12 sows per treatment on day 19 of lactation and sow feed intake was recorded daily throughout lactation. Piglets were weighed at 24 h (after standardization of litter size), and on days 7, 14, and 21 (weaning). The TRT gilts gained less BW than CTL gilts (17.3 vs. 31.7 kg; P < 0.01) from days 28 to 75 of gestation and more BW (29.5 vs. 21.9 kg; P < 0.01) from days 75 to 110, but their overall gain from mating to day 110 was lower (61.4 vs. 67.2 kg; P < 0.05). Metabolic status during gestation was affected, with TRT gilts having less IGF-1 and urea, and more FFA than CTL gilts on day 75 (P < 0.01), and more urea on day 110 (P < 0.01). Growth rate of suckling piglets, sow lactation feed intake, and standard milk composition in late lactation (DM, fat, protein, lactose) were not affected by treatment (P > 0.10). In conclusion, diet deprivation of gilts as of day 28 of gestation followed by overfeeding from day 75 of gestation until farrowing did not improve lactation performance. It is likely that the compensatory growth that took place in late gestation was not adequate to illicit beneficial effects.