A total of 84 sows (PIC Line 1050) were blocked according to day of farrowing and parity and allotted in a 2 × 2 factorial arrangement of treatments with lactation feed intake (ad libitum vs. restricted) and creep feeding (no vs. yes) as factors. Sows fed for ad libitum intake (ad libitum-fed) were allowed free access to a common lactation diet (3,503 kcal of ME/kg, 0.97% standardized ileal digestible Lys), and sows with restricted intake (restricted-fed) were fed 25% less than ad libitum-fed sows. A creep diet (3,495 ME/kg, 1.56% standardized ileal digestible Lys) with 1.0% chromic oxide was offered to creep-fed pigs from d 3 to 21. Fecal samples from creep-fed pigs were taken with sterile swabs on d 7, 14, and 21, and color was assessed to categorize pigs as eaters or non-eaters. There were no interactions (P > 0.15) between lactation feed intake and creep feeding. Ad libitum-fed sows had greater (P < 0.01) total feed intake and ADFI (99.4, 4.9 kg) than restricted-fed sows (67.9, 3.6 kg). Ad libitum-fed sows had reduced BW loss (−15 vs. −24 kg; P < 0.01), improved total (46.7 vs. 43.0 kg; P < 0.04) and daily (2.56 vs. 2.36 kg; P < 0.04) BW gains of litters, and increased (90 vs. 71%; P < 0.03) percentage of sows returning to estrus by d 14 compared with restricted-fed sows. Creep feeding for 18 d did not affect (P > 0.34) sow BW and backfat loss but increased days to estrus (5.4 vs. 4.9 d; P < 0.03). Creep feeding had no (P > 0.16) effect on preweaning growth performance. Postweaning performance of creep-fed and non-creep-fed pigs was similar (P > 0.86). When individual pigs were categorized on the basis of creep feed consumption category, eaters had greater (P < 0.05) ADG (393, 376, and 378 g) and total BW gains (11.0, 10.5, and 10.6 kg) than non-eaters or non-creep-fed pigs. In conclusion, creep feeding for 18 d did not affect preweaning and lactating sow performance. Low feed intake during lactation negatively affected sow and litter performance. Creating more creep-feed eaters during the lactation period may benefit postweaning performance. Therefore, dietary and nondietary factors that can enhance the proportion of eaters in litters should be investigated.

A total of 684 sows from breeding groups over 6 wk was used to compare three methods of feeding during gestation on gestation and lactation performance. Control gilts and sows were fed according to body condition based on a scale of 1 to 5 (1 = thin, 5 = fat). Sows were visually assessed for body condition at breeding and were assigned a daily feed allowance to achieve a BCS of 3 at farrowing. Treatment 2 used feeding levels based on backfat thickness (measured between d 0 and 5 after breeding) and weight at weaning for sows or service for gilts. Feed allowance was calculated to achieve a target backfat of 19 mm at farrowing, and remained constant from d 0 to 101 of gestation. Feed allowances were based on modeled calculations of energy and nutrient requirements to achieve target sow maternal weight and backfat gains. Treatment 3 was identical to Treatment 2, except that feeding pattern was altered for thin sows and gilts (< 5mm at service) in an attempt to reach 19 mm by d 36 of gestation. Sows were weighed at the previous weaning, and gilts were weighed at service, with both weighed again between d 112 and 114 of gestation. Backfat was measured between d 0 and 5, and again between d 108 and 113 of gestation. At farrowing, sows on Treatments 2 and 3 had 19 and 19.1 mm of backfat, respectively, whereas control sows tended to have greater (P < 07) backfat (20 mm). On average, sows targeted to gain 6 to 9 mm of backfat failed to reach target gains regardless of feeding method. Feeding sows in gestation based on backfat (Treatments 2 and 3) resulted in a numerically higher proportion of sows in the target backfat range of 17 to 21 mm (40.2, 53.3, and 52.6% for control and Treatments 2 and 3, respectively) at farrowing and a numerically lower percentage of fat sows (>21 mm), but no difference in the percentage of thin sows (<17 mm) compared with feeding based on body condition. In conjunction with this observation, sows fed based on BCS were fed higher (P < 0.05) feeding levels in gestation than were sows fed based on backfat depth. Gestation feeding method had no effect on performance during lactation. Feed intake in lactation was lower (P < 0.05) for high backfat sows (> 21 mm) at farrowing compared with sows with <21 mm. The high proportion of sows in the optimal backfat category demonstrates that feeding based on backfat and BW has potential for facilitating more precise feeding during gestation.

A trial was conducted to biochemically explain the decreased lipid deposition and increased protein accretion observed in pigs fed carnitine. Our hypothesis was that an increase in the ratio of acetyl CoA:CoA-SH produced by stimulation of fatty acid oxidation by supplemental L-carnitine may decrease branched-chain alpha-keto acid dehydrogenase activity and increase pyruvate carboxylase activity. Such changes could reduce oxidative loss of branched-chain amino acids and provide more carbons for amino acid biosynthesis. Yorkshire gilts (n = 36; 12 per treatment) were fed a control diet or diets containing either 50 or 125 ppm of added L-carnitine during growth from 56 to 120 kg. After slaughter, the semitendinosus muscle and liver were collected for isolation of mitochondria and hepatocytes. Increasing dietary L-carnitine did not influence growth performance (P > 0.10) but linearly decreased (P < 0.05) 10th rib backfat thickness and increased (linear, P < 0.05) percentages of lean and muscle. The rates of [1-(14)G]palmitate oxidation in isolated hepatocytes and isolated mitochondria, and incorporation of [35S]methionine into the acid insoluble fraction of isolated hepatocytes were increased (linear, P < 0.01) in pigs fed L-carnitine. Flux through branched-chain alpha-keto acid dehydrogenase linearly decreased (P < 0.01) in isolated liver and muscle mitochondria with increasing dietary carnitine. Flux through pyruvate carboxylase was increased (linear, P < 0.01) in isolated mitochondria from liver of pigs fed carnitine, and assays with particle-free extracts indicated that the amount of mitochondrial pyruvate carboxylase was tripled by feeding carnitine (linear, P < 0.01). The association of increased protein accretion and reduced backfat thickness with greater rates of palmitate oxidation, more rapid flux through pyruvate carboxylase, and reduced flux through branched-chain alpha-keto acid dehydrogenase suggests pigs fed carnitine are more able to use fat for energy, divert carbon toward synthesis of amino acids, and spare branched-chain amino acids for protein synthesis.

In 2 experiments, 602 pigs were used to evaluate the effects of fish meal, fermented soybean meal, or dried porcine solubles on phase 2 nursery pig performance. In Exp. 1, nursery pigs (n = 252; PIC TR4 × 1050; 6.8 kg initial BW and 7 d after weaning) were fed: 1) a control diet containing no specialty protein sources and the control diet with 2) 5% fish meal, 3) 3.5% dried porcine solubles, 4) 6.0% fermented soybean meal, 5) a combination of 1.75% fermented soybean meal and 1.75% dried porcine solubles, or 6) a combination of 3.0% fermented soybean meal and 2.5% fish meal. There were 7 replications with 6 pigs per pen. Experimental diets were fed for 14 d, and then all pigs were fed a common diet without specialty protein sources for 14 d. From d 0 to 14, pigs fed dried porcine solubles alone or with fermented soybean meal had improved (P < 0.05) ADG and G:F compared with pigs fed all other diets. Overall (d 0 to 28), pigs fed dried porcine solubles had improved (P = 0.01) ADG (421 vs. 383 g) and G:F (0.77 vs. 0.73) compared with pigs fed the control diet and had improved (P = 0.03) G:F (0.77 vs. 0.74) compared with pigs fed the combination of fermented soybean meal and fish meal. In Exp. 2, nursery pigs (n = 350; PIC C22 × 1050; 6.1 kg initial BW and 7 d after weaning) were fed 1) a control diet containing no specialty protein sources and the control diet with 2) 3% fish meal, 3) 6% fish meal, 4) 3.75% fermented soybean meal, 5) 7.50% fermented soybean meal, 6) a combination of 1.88% fermented soybean meal and 1.88% dried porcine solubles, or 7) a combination of 3.75% fermented soybean meal and 3.75% dried porcine solubles. There were 10 replications with 5 pigs per pen. Experimental diets were fed from d 0 to 14, and then all pigs were fed a common diet without specialty protein sources for 21 d. From d 0 to 14, pigs fed increasing fish meal had increased (quadratic, P = 0.05) ADFI. Pigs fed increasing fermented soybean meal had improved (quadratic, P = 0.01) G:F. Pigs fed the combination of fermented soybean meal and dried porcine solubles had improved (P < 0.05) ADG and G:F compared with pigs fed diets containing fish meal and had improved (P < 0.05) ADG and ADFI compared with pigs fed diets containing fermented soybean meal. Overall (d 0 to 35), pigs fed diets with increasing amounts of fermented soybean meal had improved (quadratic, P = 0.03) G:F. Feeding nursery pigs diets containing dried porcine solubles, either alone or in combination with fermented soybean meal, can improve growth performance compared with those fed high concentrations of soybean meal or fish meal.

Three experiments were conducted to evaluate the effects of increasing dietary Cu and Zn on weanling pig performance. Diets were fed in 2 phases: phase 1 from d 0 to 14 postweaning and phase 2 from d 14 to 28 in Exp. 1 and 2 and d 14 to 42 in Exp. 3. The trace mineral premix, included in all diets, provided 165 mg/kg of Zn from ZnSO₄ and 16.5 mg/kg of Cu from CuSO₄. In Exp. 1, treatments were arranged in a 2 × 3 factorial with main effects of added Cu from tri-basic copper chloride (TBCC; 0 or 150 mg/kg) and added Zn from ZnO (0, 1,500, or 3,000 mg/kg from d 0 to 14 and 0, 1,000, or 2,000 mg/kg from d 14 to 28). No Cu × Zn interactions were observed (P > 0.10). Adding TBCC or Zn increased (P < 0.05) ADG and ADFI during each phase. In Exp. 2, treatments were arranged in a 2 × 3 factorial with main effects of added Zn from ZnO (0 or 3,000 mg/kg from d 0 to 14 and 0 or 2,000 mg/kg from d 14 to 28) and Cu (control, 125 mg/kg of Cu from TBCC, or 125 mg/kg of Cu from CuSO₄). No Cu × Zn interactions (P > 0.10) were observed for any performance data. Adding ZnO improved (P < 0.02) ADG and ADFI from d 0 to 14 and overall. From d 0 to 28, supplementing CuSO₄ increased (P < 0.02) ADG, ADFI, and G:F, and TBCC improved (P = 0.006) ADG. In Exp. 3, the 6 dietary treatments were arranged in a 2 × 2 factorial with main effects of added Cu from CuSO₄ (0 or 125 mg/kg) and added Zn from ZnO (0 or 3,000 mg/kg from d 0 to 14 and 0 or 2,000 mg/kg from d 14 to 42). The final 2 treatments were feeding added ZnO alone or in combination with CuSO₄ from d 0 to 14 and adding CuSO₄ from d 14 to 42. Adding ZnO increased (P < 0.04) ADG, ADFI, and G:F from d 0 to 14 and ADG from d 0 to 42. Dietary CuSO₄ increased (P < 0.004) ADG and ADFI from d 14 to 42 and d 0 to 42. From d 28 to 42, a trend for a Cu × Zn interaction was observed (P = 0.06) for ADG. This interaction was reflective of the numeric decrease in ADG for pigs when Cu and Zn were used in combination compared with each used alone. Also, numerical advantages were observed when supplementing Zn from d 0 to 14 and Cu from d 14 to 42 compared with all other Cu and Zn regimens. These 3 experiments show the advantages of including both Cu and Zn in the diet for 28 d postweaning; however, as evident in Exp. 3, when 3,000 mg/kg of Zn was added early and 125 mg/kg of Cu was added late, performance was similar or numerically greater than when both were used for 42 d.

Our objective was to determine an optimum Lys:calorie ratio (g of total dietary Lys/Mcal of ME) for 35- to 120-kg barrows and gilts (Pig Improvement Company, L337 × C22) in a commercial finishing environment. Seven (3 barrow and 4 gilt) trials were conducted using randomized complete block designs (42 pens per trial, a total of 7,801 pigs). Six treatments with increasing Lys:calorie ratio were used in each study. Diets were corn-soybean meal-based with 6% choice white grease. Lysine:calorie ratios were attained by adjusting the amount of corn and soybean meal. No crystalline Lys was used. In barrow trial 1 (43 to 70 kg), increasing the Lys:calorie ratio (2.21, 2.55, 2.89, 3.23, 3.57, and 3.91) increased (quadratic, P < 0.01) ADG, G:F, income over feed costs (IOMFC), and feed cost per kilogram of gain, and decreased (linear, P < 0.01) backfat. In barrow trial 2 (69 to 93 kg), increasing the Lys:calorie ratio (1.53, 1.78, 2.03, 2.28, 2.53, and 2.78) improved (linear, P < 0.01) ADG, G:F, and IOMFC, and decreased (quadratic, P < 0.01) backfat. In barrow trial 3 (102 to 120 kg), increasing the Lys:calorie ratio (1.40, 1.60, 1.80, 2.00, 2.20, and 2.40) increased (linear, P < 0.03) ADG and G:F, and numerically improved (linear, P = 0.12) IOMFC. In gilt trials 1 (35 to 60 kg), 2 (60 to 85 kg), and 3 (78 to 103 kg), increasing the Lys:calorie ratio (2.55, 2.89, 3.23, 3.57, 3.91, and 4.25; 1.96, 2.24, 2.52, 2.80, 3.08, and 3.36; and 1.53, 1.78, 2.03, 2.28, 2.53, and 2.78, respectively) improved (quadratic, P < 0.04) ADG, G:F, IOMFC, and feed cost per kilogram of gain, and decreased (linear, P < 0.01) backfat. In gilt trial 4 (100 to 120 kg), increasing the Lys:calorie ratio (1.40, 1.60, 1.80, 2.00, 2.20, and 2.40) improved (linear, P < 0.02) ADG, G:F, LM depth, IOMFC, and (quadratic, P < 0.06) feed cost per kilogram of gain. These studies suggest that feed cost per kilogram of gain decreases, and reductions in biological performance and IOMFC are rather modest when feeding marginally Lys-deficient diets early (35 to 70 kg) in the grower-finishing period compared with the more severe penalties in growth and economic performance of feeding marginally deficient diets in the late finishing period (70 kg to slaughter). The equations (Lys:calorie ratio = −0.0133 × BW, kg, + 3.6944 and = −0.0164 × BW, kg, + 4.004, for barrows and gilts, respectively) best describe our interpretation of the Lys:calorie ratio that met biological requirements and optimized IOMFC on these pigs (PIC, L337 × C22; 35 to 120 kg) in this commercial finishing environment.