Effects of increasing soybean meal in corn-based diets on the growth performance of late finishing pigs.

Three experiments were conducted to determine the effects of increasing soybean meal (SBM) levels by replacing feed-grade amino acids (AA) in corn, corn dried distillers grains with solubles (DDGS), and corn-wheat midds-based diets on growth performance of late finishing pigs (n = 4,406) raised in commercial facilities. Across all experiments, pens of pigs were blocked by initial bodyweight (BW) and randomly assigned to 1 of 5 dietary treatments. All diets were formulated to contain 0.70% standardized ileal digestible (SID) Lys and varying amounts of feed-grade AA. All diets were formulated to meet or exceed minimum essential AA requirement estimates as a ratio to Lys. In Exp. 1, 1,793 pigs (initially 104.9 ± 4.9 kg) were fed corn-based diets and pens of pigs were assigned treatments with increasing SBM from 5% to 20%. Overall, average daily gain (ADG) and feed efficiency (G:F) improved (linear and cubic, P ≤ 0.02) as dietary SBM increased, with the greatest improvement observed as SBM increased from 5% to 8.75% and little improvement thereafter. In Exp. 2, 1,827 pigs (initially 97.9 ± 4.3 kg) were fed diets containing 25% DDGS with SBM levels increasing from 0% to 16%. Overall, feed efficiency marginally improved (linear, P ≤ 0.10) as SBM increased, with the greatest performance observed when diets contained 8% SBM and similar performance thereafter with 12 or 16% dietary SBM. In Exp. 3, 786 pigs (initially 96.7 ± 3.2 kg) were fed diets that contained 30% wheat midds and dietary SBM from 0% to 16%. Final BW of pigs increased (linear, P < 0.05) and overall ADG and G:F improved (linear and cubic, P < 0.05) as SBM increased. The combined results of the three experiments suggest that inclusion of at least 4% to 8% dietary SBM at the expense of feed-grade amino acids in corn-based diets with or without grain coproducts can improve growth performance of late-finishing (greater than 100 kg) pigs.

Evaluation of supplemental fat sources and pre-farrow essential fatty acid intake on lactating sow performance and essential fatty acid composition of colostrum, milk, and adipose tissue.

A total of 91 sows (Line 241, DNA Genetics) were used to evaluate the effects of supplemental fat sources and essential fatty acid intake on sow farrowing performance, litter growth performance, and essential fatty acid composition of colostrum, milk, and adipose tissue. At approximatelyday 107 of gestation, sows were blocked by body weight and parity, then allotted to 1 of 5 experimental treatments as part of a 2 × 2 + 1 factorial arrangement. Experimental diets were corn-soybean meal-based with a control diet that contained no added fat or diets with 3% added fat as either beef tallow or soybean oil, with consumption of the added fat diets starting on day 107 or 112 of gestation and fed until weaning. Thus, sows were provided low essential fatty acids (EFA; as linoleic and α-linolenic acid) without supplemental fat or with beef tallow or high EFA with soybean oil. Sows were provided approximately 2.8 kg/d of their assigned lactation diet pre-farrow and then provided ad libitum access after parturition. Sows consuming diets with beef tallow had greater lactation ADFI (fat source, P = 0.030), but lower daily linoleic acid (LA) and α-linolenic acid (ALA) intake than sows that consumed diets with soybean oil (fat source, P < 0.001). Supplemental fat sources providing either low or high EFA did not influence litter growth performance (fat source, P > 0.05). Sows fed diets with beef tallow did not influence the LA composition of colostrum; however, lactation diets with high EFA provided by soybean oil on day 107 of gestation increased colostrum LA concentration compared to providing diets on day 112 of gestation (fat source × time, P = 0.084; time, P < 0.001). Additionally, regardless of pre-farrow timing, ALA concentration of colostrum increased when sows consumed diets with soybean oil compared to beef tallow (fat source, P < 0.001). Both LA and ALA concentrations of milk at weaning were greater for sows that consumed diets with soybean oil compared to beef tallow (fat source, P < 0.001). Furthermore, concentrations of LA and ALA within adipose tissue were greater at weaning when sows consumed diets with high EFA compared to low EFA (fat source, P < 0.05). These responses suggest that providing dietary fat sources with high concentrations of EFA can increase backfat, colostrum, and milk LA and ALA. However, in this experiment, changes in colostrum and milk composition did not influence litter growth performance.

The lactating sow secretes essential fatty acids (EFA) in colostrum and milk to support litter growth and if dietary linoleic (LA) and alpha-linolenic acid (ALA) intake during lactation are limited, subsequent reproductive function of sows may be impaired. However, the inclusion of dietary fat sources with varying EFA composition in lactation diets provided shortly prior to farrowing can increase the energy density of the diet and modify colostrum and milk fatty acid profiles that may influence litter growth performance and survivability. The first objective of this trial was to evaluate the impact of providing sows lactation diets with dietary fat sources that provide low or high EFA on colostrum, milk, and sow adipose tissue fatty acid composition. A second objective was to evaluate the timing of feeding low- or high-EFA diets within the last week of gestation on colostrum and milk EFA composition. Overall, providing dietary fat sources with high concentrations of EFA shortly prior to farrowing altered fatty acid profiles of colostrum, milk, and backfat resulting in increased LA and ALA when compared to providing sows diets with low EFA. However, changes in colostrum and milk composition did not alter litter growth performance.

A review of branched-chain amino acids in lactation diets on sow and litter growth performance.

Branched-chain amino acids (BCAA) are three essential amino acids (AA) for lactating sows; however, the effects of dietary Leu, Val, and Ile on sow and litter performance within the literature are equivocal. The BCAA are structurally similar and share the first steps of their catabolism pathway where Leu, Val, and Ile are transaminated through BCAA aminotransferase and irreversibly decarboxylated by the branched-chain α-ketoacid dehydrogenase complex. Although these steps are shared among BCAA, Leu is recognized as the primary stimulator due to Leu's greater affinity towards the enzymes compared to Val and Ile. Since the late 1990s, sows are producing larger and heavier litters and generally consume diets with greater concentrations of Leu and crystalline AA, which may create imbalances among dietary BCAA. Research conducted with growing-finishing pigs confirms that high concentrations of Leu can impair BCAA utilization and growth performance. However, the effects of BCAA on lactating sow and litter performance are not as clearly understood. Within mammary tissue, BCAA uptake is greater than milk output of BCAA since Val, Ile, and Leu are catabolized to form non-essential AA, lactose, fatty acids, and other metabolites. Within the mammary gland, BCAA aminotransferase activity is much higher than within skeletal muscle, liver, or small intestine. Thus, competition among the BCAA, namely, between Leu and Val, can significantly inhibit Val uptake within mammary tissue. Therefore, dietary modifications that mitigate BCAA competition may positively influence Val utilization for colostrum and milk synthesis. Little data exist on Ile and Leu requirements for modern lactating sows. Although Val requirements have been extensively researched in the last 25 yr, an ideal Val:Lys has not been consistently established across experiments. Some studies concluded that total Val concentrations above 120% of Lys optimized performance, whereas others determined that increasing SID Val:Lys from 55% to 136% did not improve piglet growth performance. Although increasing dietary Val positively influences fat and protein composition of colostrum and milk, litter growth during lactation is not always positively affected. Given the competition among BCAA for utilization within mammary tissue, research evaluating the Leu and Ile requirement of modern lactating sows is warranted to fully understand the influence and interactions of BCAA on reproductive and litter growth performance.

Evaluation of essential fatty acids in lactating sow diets on sow reproductive performance, colostrum and milk composition, and piglet survivability.

Mixed parity sows (n = 3,451; PIC, Hendersonville, TN; parities 2 through 9) and their litters were used to evaluate the effects of essential fatty acid (EFA) intake on sow reproductive performance, piglet growth and survivability, and colostrum and milk composition. Our hypothesis, like observed in earlier research, was that increasing linoleic acid (LA) and α-linolenic acid (ALA) would improve sow and litter performance. At approximately day 112 of gestation, sows were randomly assigned within parity groups to 1 of 4 corn-soybean meal-wheat-based lactation diets that contained 0.5 (Control) or 3% choice white grease (CWG), 3% soybean oil (SO), or a combination of 3% soybean oil and 2% choice white grease (Combination). Thus, sows were provided diets with low LA and ALA in diets with CWG or high LA and ALA in diets that included soybean oil. Sows received their assigned EFA treatments until weaning and were then fed a common gestation and lactation diet in the subsequent reproductive cycle. Average daily feed intake during the lactation period increased (P < 0.05) for sows fed the Combination and CWG diets compared with sows fed the Control or SO diet. However, daily LA and ALA intakes of sows fed the Combination and SO diets were still greater (P < 0.05) than those of sows fed 0.5 or 3% CWG. Overall, sows consuming high EFA from the Combination or SO diets produced litters with heavier (P < 0.05) piglet weaning weights and greater (P < 0.05) litter ADG when compared with litters from sows fed diets with CWG that provided low EFA. Despite advantages in growth performance, there was no impact of sow EFA intake on piglet survivability (P > 0.10). Additionally, lactation diet EFA composition did not influence sow colostrum or milk dry matter, crude protein, or crude fat content (P > 0.10). However, LA and ALA content in colostrum and milk increased (P < 0.05) in response to elevated dietary EFA from SO. There was no evidence for differences (P > 0.10) in subsequent sow reproductive or litter performance due to previous lactation EFA intake. In conclusion, increased LA and ALA intake provided by soybean oil during lactation increased overall litter growth and pig weaning weights, reduced sow ADFI, but did not affect piglet survivability or subsequent performance of sows.

Supplemental fat sources are an effective and widely accepted strategy to increase energy density of sow lactation diets that can also provide essential fatty acids such as linoleic acid (LA) and α-linolenic acid (ALA). Currently, the effects of supplemental LA and ALA provided shortly before farrowing on colostrum and milk composition are not fully understood. Additionally, the influence of elevated LA and ALA provided in sow lactation diets on litter growth and survivability responses has not been extensively evaluated. Therefore, this trial was conducted to evaluate the effects of fat sources providing low and high LA and ALA intake on sow performance, litter growth and survivability, colostrum and milk composition, and subsequent reproductive performance. Overall, sows consuming diets with high LA and ALA provided by soybean oil produced litters with heavier piglet weaning weights and greater litter average daily gain when compared with sows consuming diets with low LA and ALA content. Increasing LA and ALA by added soybean oil also increased their content in colostrum and milk. However, there was no influence of sow LA and ALA intake on litter survivability or subsequent reproductive performance of sows.

A meta-regression analysis to evaluate the influence of branched-chain amino acids in lactation diets on sow and litter growth performance.

The branched-chain amino acids (BCAA) Ile, Leu, and Val are three dietary essential amino acids for lactating sows; however, effects of dietary BCAA on sow and litter growth performance in the literature are equivocal. Thus, a meta-regression analysis was conducted to evaluate the effects of BCAA and their interactions in lactating sow diets to predict litter growth performance, sow bodyweight change, and sow feed intake. Thirty-four publications that represented 43 trials from 1997 to 2020 were used to develop a database that contained 167 observations. Diets for each trial were reformulated using NRC. 2012. Nutrient requirements of swine. 11th ed. Washington, DC: National Academies Press nutrient loading values in an Excel-based spreadsheet. Amino acids were expressed on a standardized ileal digestible (SID) basis. Regression model equations were developed with the MIXED procedure of SAS (Version 9.4, SAS Institute, Cary, NC) and utilized the inverse of reported squared SEM with the WEIGHT statement to account for heterogeneous errors across studies. Predictor variables were assessed with a step-wise manual forward selection for model inclusion. Additionally, statistically significant (P < 0.05) predictor variables were required to provide an improvement of at least 2 Bayesian information criterion units to be included in the final model. Significant predictor variables within three optimum equations developed for litter ADG included the count of weaned pigs per litter, NE, SID Lys, CP, sow ADFI, Val:Lys, Ile:Lys, and Leu:Val. For sow BW change, significant predictor variables within two developed models included litter size at 24 h, sow ADFI, Leu:Lys, and Ile + Val:Leu. The optimum equation for sow ADFI included Leu:Trp, SID Lys, NE, CP, and Leu:Lys as significant predictor variables. Overall, the prediction equations suggest that BCAA play an important role in litter growth, sow BW change, and feed intake during lactation; however, the influence of BCAA on these criteria is much smaller than that of other dietary components such as NE, SID Lys, sow ADFI, and CP.

The branched-chain amino acids Ile, Leu, and Val are three dietary essential amino acids necessary for both skeletal and milk protein synthesis of lactating sows. Since the late 1990s, sows are producing much larger and heavier litters and commonly receive diets with greater concentrations of crystalline amino acids. This practice unintentionally increases Leu and may create imbalances among the dietary branched-chain amino acids. Nonetheless, sow and litter growth responses to branched-chain amino acids and large neutral amino acids such as Trp are equivocal within the available literature. Therefore, a meta-regression analysis was conducted to evaluate the effects of branched-chain amino acids and their interactions in lactating sow diets to predict litter growth performance, sow bodyweight change, and sow feed intake. The developed models for litter average daily gain suggest that Leu, Ile, and Val impact litter growth, but the effects of branched-chain amino acids are much smaller than the effects of dietary net energy, Lys, and crude protein. Furthermore, the developed models suggest that increasing Leu:Lys and reducing Ile + Val:Leu ratios can positively influence sow bodyweight change during lactation. Additionally, our model suggests that reduced Leu:Trp and increased Leu:Lys positively influence sow feed intake during lactation.

Effects of supplementing late-gestation sow diets with zinc on preweaning mortality of pigs under commercial rearing conditions.

The objective of this experiment was to determine preweaning survival of pigs when sows were supplemented with 3 dietary levels of zinc (Zn) in late gestation. Gilts and sows (n = 339) were assigned to 1 of 3 dietary treatments based on parity. Dietary treatments were 1) Control-sows fed a corn-soybean meal-based diet containing 125 ppm total supplemental Zn supplied by ZnSO4 (75 ppm Zn) and AvailaZn (50 ppm Zn, CON); 2) Intermediate-as Control + 240 ppm supplemental Zn as ZnSO4 (INT); and 3) High-as Control + 470 ppm supplemental Zn as ZnSO4 (HI). Final supplemental Zn concentrations of the 3 dietary treatments were 1) CON-125 ppm; 2) INT-365 ppm; and 3) HI-595 ppm. Sows received dietary treatments from about day 85 of gestation until farrowing. Individual piglet birth weights were recorded within 12 h of parturition. Instances of piglet mortality were recorded daily. The statistical model considered fixed effects of treatment and random effects of parity. Piglets from sows fed the INT diet had heavier (P < 0.05) birth weights than those fed CON (1.42 vs. 1.38 kg, respectively), while offspring from sows fed HI tended to have heavier (P < 0.10) birth weights (1.40 kg) than pigs from INT sows. Furthermore, incidence of low birth weight pigs was less (P < 0.05) for sows consuming INT compared with sows fed CON and HI. Despite differences in birth weight, there were no differences (P > 0.05) in total pigs born, born alive, or weaned, nor differences in individual piglet gain or weaning weight across treatments. Mortality of low birth weight pigs was lowest (P < 0.05) for offspring from sows fed HI (28.1%) compared with offspring from sows fed INT (36.1%) and CON (38.3%). Similarly, overall piglet mortality tended to decrease (P < 0.10) as dietary Zn content increased (CON: 15.0%, INT: 13.2%, and HI: 12.2%). A subset of pigs (n = 420, n = 140/treatment) were selected at weaning to evaluate effects of dietary treatment on postweaning performance. There were no significant effects of sow Zn supplementation on final body weight, days to market, or carcass characteristics of market pigs. Overall, effects of supplemental dietary Zn at 365 and 595 ppm in late gestation improved preweaning survival of low birth weight piglets and reduced overall preweaning mortality of piglets.

Comparative digestibility of polysaccharide-complexed zinc and zinc sulfate in diets for gestating and lactating sows.

We hypothesized that the digestibility of a zinc polysaccharide complex is greater than zinc sulfate when sows consume high fiber diets containing corn dried distillers grains with solubles (DDGS). Gilts and sows (n = 32) were blocked according to parity and assigned randomly to one of four dietary treatments (n = 8 sows per treatments). Dietary treatments consisted of: 1) Control (ConZnSO4)-corn-soybean meal-based diet + 100 ppm supplemental Zn from ZnSO4; 2) Control PSZn (ConPSZn)-corn-soybean meal-based diet + 100 ppm supplemental Zn from Zn polysaccharide complex; 3) DDGS/ZnSO4-corn-soybean meal-40% DDGS gestation diet and a 30% DDGS lactation diet, with each containing 100 ppm supplemental Zn from ZnSO4; 4) DDGS/PSZn-corn-soybean meal-40% DDGS gestation diet and a 30% DDGS lactation diet, with each containing 100 ppm supplemental Zn from Zn polysaccharide complex. A fifth dietary treatment was imposed using a subset of sows (n = 20) to determine basal Zn losses in gestating and lactating sows fed corn-soybean meal-based diets containing no supplemental Zn. Nutrient balance experiments were conducted in both gestation and lactation to evaluate the digestibility of Zn sources of the four dietary treatments and to determine basal Zn losses when no supplemental Zn was provided. The statistical model included fixed effects of diet, Zn source, and their interaction, and random effects of parity. Estimated endogenous losses of Zn were used to adjust apparent total tract digestibility (ATTD) to true total tract digestibility (TTTD) of Zn in the four dietary treatment balance periods. There were no differences in Zn concentrations of urine, plasma, colostrum, or milk samples among treatments at any time of the experiment (P > 0.05). Gestating sows fed DDGS/PSZn had improved (P < 0.05) ATTD, TTTD, and overall retention of Zn compared with both Control treatments, with the DDGS/ZnSO4 treatment responses being intermediate. Lactating sows consuming diets without DDGS and supplemented with Zn polysaccharide complex had the greatest (P < 0.05) ATTD, TTTD, and retention of Zn, which were opposite to responses observed in gestation. Furthermore, ATTD, TTTD, and Zn retention for lactating sows consuming DDGS/PSZn were less (P < 0.05) than all other treatments. Overall, zinc digestibility of ZnSO4 and PSZn appears to be differentially influenced by the stage of the reproductive cycle and presence of dietary fiber from DDGS.