Effects of dietary L-carnitine and ractopamine HCl on the metabolic response to handling in finishing pigs.

Two experiments (384 pigs; C22 × L326; PIC) were conducted to determine the interactive effect of dietary L-carnitine and ractopamine HCl (RAC) on the metabolic response of pigs to handling. Experiments were arranged as split-split plots with handling as the main plot and diets as subplots (4 pens per treatment). Dietary L-carnitine (0 or 50 mg/kg) was fed from 36.0 kg to the end of the experiments (118 kg), and RAC (0 or 20 mg/kg) was fed the last 4 wk of each experiment. At the end of each experiment, 4 pigs per pen were assigned to 1 of 2 handling treatments. Gently handled pigs were moved at a moderate walking pace 3 times through a 50-m course and up and down a 15° loading ramp. Aggressively handled pigs were moved as fast as possible 3 times through the same course, but up and down a 30° ramp, and shocked 3 times with an electrical prod. Blood was collected immediately before and after handling in Exp. 1 and immediately after and 1 h after handling in Exp. 2. Feeding RAC increased (P < 0.01) ADG and G:F, but there was no effect (P > 0.10) of L-carnitine on growth performance. In Exp. 1 and 2, aggressive handling increased (P < 0.01) blood lactate dehydrogenase (LDH), lactate, cortisol, and rectal temperature and decreased blood pH. In Exp. 1, there was a RAC × handling interaction (P < 0.06) for the difference in pre- and posthandling blood pH and rectal temperature. Aggressively handled pigs fed RAC had decreased blood pH and increased rectal temperature compared with gently handled pigs, demonstrating the validity of the handling model. Pigs fed RAC had increased (P < 0.01) LDH compared with pigs not fed RAC. Pigs fed L-carnitine had increased (P < 0.03) lactate compared with pigs not fed L-carnitine. In Exp. 2, pigs fed RAC had lower (P < 0.02) blood pH immediately after handling, but pH returned to control levels by 1 h posthandling. Lactate, LDH, cortisol, and rectal temperature changes from immediately posthandling to 1 h posthandling were not different (P > 0.10) between pigs fed L-carnitine and those fed RAC, indicating that L-carnitine did not decrease recovery time of pigs subjected to aggressive handling. These results suggest that pigs fed 20 mg/kg of RAC are more susceptible to stress when handled aggressively compared with pigs not fed RAC. Dietary L-carnitine fed in combination with RAC did not alleviate the effects of stress. This research emphasizes the importance of using proper animal handling techniques when marketing finishing pigs fed RAC.

Interactive effects of dietary ractopamine HCl and L-carnitine on finishing pigs: I. Growth performance.

A total of 2,152 pigs (C22 × 336 PIC) were used in 4 experiments to determine the interactive effects of dietary l-carnitine and ractopamine HCl (RAC) on finishing pig growth performance. All trials were arranged as factorial arrangements with main effects of l-carnitine (0, 25, or 50 mg/kg in Exp. 1 and 2 and 0 or 50 mg/kg in Exp. 3 and 4) and RAC (0, 5, or 10 mg/kg in Exp. 1 and 0 or 10 mg/kg in Exp. 2, 3, and 4). Dietary carnitine was fed from 38 to 109 kg (Exp. 1 and 3) or for the last 4 or 3 wk before slaughter (118 kg; Exp. 2 and 4, respectively). Ractopamine HCl was fed for 4 wk (Exp. 1, 2, and 3) or 3 wk (Exp. 4) before slaughter. Experiments 1 and 2 were conducted in university research facilities, and Exp. 3 and 4 were conducted in a commercial research facility. All diets were formulated to contain 1.00% total Lys during the last phase of each experiment. In all experiments, pigs fed RAC had increased (P < 0.05) ADG and G:F compared with pigs fed no RAC. Feeding l-carnitine before the RAC feeding period did not affect pig growth performance. In Exp. 1 and 2, l-carnitine did not affect ADG during the last 4 wk; however, in Exp. 2, G:F tended (quadratic; P = 0.07) to improve with increasing l-carnitine. In Exp. 3, l-carnitine × RAC interactions were observed (P < 0.04) for ADG and G:F. Both added l-carnitine and RAC improved performance, but the response was not additive. In Exp. 4, pigs fed l-carnitine had increased (P < 0.04) ADG (0.88 vs. 0.84 kg) and G:F (0.36 vs. 0.35) compared with pigs fed no l-carnitine, and the response was additive to that of RAC. Analysis of treatments common to all experiments showed that pigs fed RAC had increased (P < 0.01) ADG (1.03 vs. 0.93 kg) and G:F (0.40 vs. 0.35) compared with pigs fed no RAC. Pigs fed l-carnitine tended to have increased (P = 0.07) ADG (1.00 vs. 0.96 kg) and improved (P < 0.01) G:F (0.38 vs. 0.37) compared with pigs not fed l-carnitine. These results confirm that RAC improves growth performance of finishing pigs. Added l-carnitine improved growth performance of finishing pigs, and the greatest response was observed in Exp. 3 and 4, which were conducted in commercial research environments. These experiments imply that adding l-carnitine to a finishing diet does not enhance the growth effects of RAC and that effects of RAC and l-carnitine on ADG and G:F are independent.

Interactive effects of dietary ractopamine HCl and L-carnitine on finishing pigs: II. Carcass characteristics and meat quality.

Three experiments using 1,356 pigs (C22 × 336 PIC) were conducted to determine the interactive effects of dietary L-carnitine and ractopamine hydrochloride (RAC) on carcass characteristics and meat quality of finishing pigs. Experiments were arranged as factorials with main effects of L-carnitine and RAC; L-carnitine levels were 0, 25, or 50 mg/kg in Exp. 1 and 2 and 0 or 50 mg/kg in Exp. 3, and RAC levels of 0, 5, or 10 mg/kg in Exp. 1 and 0 or 10 mg/kg in Exp. 2 and 3. Dietary L-carnitine was fed from 38 kg to slaughter (109 and 118 kg in Exp. 1 and 3, respectively) or for 4 wk before slaughter (109 kg in Exp. 2). Ractopamine HCl was fed for 4 wk in all experiments. Exp. 1 and 2 were conducted at university research facilities (2 pigs per pen), and Exp. 3 was conducted in a commercial research barn (23 pigs per pen). In Exp. 1, an L-carnitine × RAC interaction (P < 0.02) was observed for LM visual color, L*, and a*/b*. In pigs fed RAC, increasing L-carnitine decreased L* and increased visual color scores and a*/b* compared with pigs not fed RAC. Ultimate pH tended to increase (linear, P < 0.07) with increasing L-carnitine. Drip loss decreased (linear, P < 0.04) in pigs fed increasing L-carnitine. In Exp. 2, firmness scores decreased in pigs fed increasing L-carnitine when not fed RAC, but firmness scores increased and drip losses decreased with increasing L-carnitine when RAC was added to the diet (L-carnitine × RAC interaction, P < 0.04). Percentage lean was greater (P < 0.01) for pigs fed RAC in Exp. 2. In Exp. 3, fat thickness decreased and lean percentage increased in pigs fed L-carnitine or RAC, but the responses were not additive (L-carnitine × RAC interaction, P < 0.03). Furthermore, pigs fed L-carnitine tended (P < 0.06) to have decreased LM drip loss percentage whereas pigs fed RAC had decreased (P < 0.05) 10th rib and average backfat and decreased drip loss than pigs fed diets without RAC. These results suggest that dietary RAC increased carcass leanness and supplemental L-carnitine reduced LM drip loss when fed in combination with RAC.

Influence of dietary L-carnitine and chromium picolinate on blood hormones and metabolites of gestating sows fed one meal per day.

Gestating sows (n = 44; parity = 2.0; BW = 208 kg) were used to determine the effects of dietary L-carnitine and Cr picolinate (CrP) on daily blood hormone and metabolite profiles. Diets were formulated as a 2 x 2 factorial with L-carnitine (0 or 50 ppm) and CrP (0 or 200 ppb) and were fed from breeding through gestation, lactation, and 28 d into the subsequent gestation, at which time blood collection occurred. Sows were fed 1 meal per day during gestation (2.04 kg from breeding until d 100 and 2.95 kg from d 100 until farrowing) and ad libitum during lactation. Sows were fitted with indwelling venous catheters, and blood (plasma) was collected at feeding, then once every 15 min for the first 3 h after feeding, and at 6, 9, 15, 20, and 24 h after feeding. Postfeeding and overall insulin and connecting peptide of insulin (c-peptide) was decreased for sows fed diets with CrP or L-carnitine and was greatest for sows fed the control diet; however, sows fed both L-carnitine and CrP had an intermediate response (L-carnitine x CrP, P < 0.01). Postfeeding glucose peak was decreased (P < 0.05) in sows fed diets with L-carnitine, CrP, or both, vs. the control, and mean glucose concentration was decreased (P < 0.01) for sows fed diets with CrP. L-Carnitine decreased (P < 0.04) the NEFA concentration. Sows fed diets with CrP exhibited increased (P < 0.03) postfeeding and overall NEFA and greater (P < 0.02) fasting and overall glycerol. Overall plasma urea N was lowest for sows fed the diet with L-carnitine; however, diets containing CrP had intermediate responses compared with the control (L-carnitine x CrP, P < 0.005). Sows fed diets with L-carnitine had greater (P < 0.008) IGF-I from 3 to 24 h after feeding and tended to exhibit greater (P < 0.06) overall IGFBP-3. Sows fed the diets with CrP had greater (P < 0.05) IGFBP-3 from 2 to 20 h after feeding. No differences were observed for glucagon or triacylglycerol (P > 0.10). The changes in metabolites and metabolic hormones indicate that both L-carnitine and CrP influence energy metabolism of gestating sows; however, their effects on blood hormones and metabolites differ. Thus, the improvement in energy status from adding both L-carnitine and CrP may have an additive effect on reproductive performance of sows.

Dietary L-carnitine increases plasma leptin concentrations of gestating sows fed one meal per day.

Thirty-four sows (parity=1.8; BW=206 kg) were used to determine the influence of L-carnitine and/or chromium tripicolinate on plasma leptin concentrations of gestating sows fed one meal daily. Treatments were arranged in a 2 x 2 factorial with main effects of carnitine (0 or 50 ppm) and chromium (0 or 200 ppb). Diets were fed for approximately 167 days (through one gestation, the following lactation, the interval from weaning to estrus, and 28 days into the following gestation) prior to blood collection. Leptin concentration was determined in plasma that was collected at feeding, every 15 min for the first 3h after feeding, and at 6, 9, 15, 20, and 24h after feeding. Sows fed diets containing carnitine had greater (P<0.02) overall mean plasma leptin concentrations and greater (P<0.05) leptin concentrations at 2.25, 3, 6, 15, 20, and 24h after feeding compared to sows fed either the control diet or the diet containing chromium. Leptin concentrations of sows fed diets containing carnitine also were greater (P<0.05) than control sows at 2.5 and 2.75 h postprandial and greater than (P<0.05) sows fed diets with both carnitine and chromium at 6h after feeding. Chromium had no effect (P>0.10) on plasma leptin concentration. These results suggest that dietary carnitine, but not chromium, increases circulating leptin in gestating sows fed one meal per day. These results may help to explain the improvements in reproductive function previously observed from feeding sows diets containing carnitine.

Effects of increasing dietary L-carnitine on growth performance of weanling pigs.

Four experiments were conducted to evaluate the effects of supplementing graded levels (0 to 100 ppm) of L-carnitine to the diet of weanling pigs on growth performance during a 34- to 38-d experimental period. A fifth experiment was conducted to determine the effects of addition of L-carnitine to diets with or without added soybean oil (SBO) on growth performance. In Exp. 1, 128 pigs (initial BW = 5.5 kg) were allotted to four dietary treatments (six pens per treatment of four to six pigs per pen). Dietary treatments were a control diet containing no added L-carnitine and the control diet with 25, 50, or 100 ppm of added L-carnitine. In Exp. 2, 3, and 4, pigs (4.8 to 5.6 kg of BW) were allotted to five dietary treatments consisting of either a control diet containing no added L-carnitine or the control diet with 25, 50, 75, or 100 ppm of added L-carnitine. All diets in Exp. 1 to 4 contained added soybean oil (4 to 6%). There were seven pens per treatment (four to five pigs per pen) in Exp. 2, whereas Exp. 3 and 4 had five and six pens/treatment (eight pigs per pen), respectively. In general, dietary carnitine additions had only minor effects on growth performance during Phases 1 and 3; however, dietary L-carnitine increased (linear [Exp. 1], quadratic [Exp. 2 to 4], P < 0.03) ADG and gain:feed (G:F) during Phase 2. The improvements in growth performance during Phase 2 were of great enough magnitude that carnitine addition tended to increase ADG (linear, P < 0.10) and improve G:F (quadratic, P < 0.02) for the entire 38-d period. In Exp. 5, 216 weanling pigs (5.8 kg of BW) were allotted (12 pens/treatment of four to five pigs per pen) to four dietary treatments. The four dietary treatments were arranged in a 2 x 2 factorial with main effects of added SBO (0 or 5%) and added L-carnitine (0 or 50 ppm). Pigs fed SBO tended (P < 0.07) to grow more slowly and consumed less feed compared with those not fed SBO, but G:F was improved (P < 0.02). The addition of L-carnitine did not affect (P > 0.10) ADG or ADFI; however, it improved (P < 0.03) G:F. Also, the increase in G:F associated with L-carnitine tended to be more pronounced for pigs fed SBO than those not fed SBO (carnitine x SBO, P < 0.10). These results suggest that the addition of 50 to 100 ppm of added L-carnitine to the diet improved growth performance of weanling pigs. In addition, supplemental L-carnitine tended to be more effective when SBO was provided in the diet.

Effect of dietary L-carnitine on growth performance and body composition in nursery and growing-finishing pigs.

Two experiments were conducted to determine the effect of dietary L-carnitine on growth performance and carcass composition of nursery and growing-finishing pigs. In Exp. 1,216 weanling pigs (initially 4.9 kg and 19 to 23 d of age) were used in a 35-d growth trial. Pigs were blocked by weight in a randomized complete block design (six pigs per pen and six pens per treatment). Four barrows and four gilts were used to determine initial carcass composition. L-Carnitine replaced ground corn in the control diets to provide 250, 500, 750, 1,000, or 1,250 ppm. On d 35, three barrows and three gilts per treatment (one pig/block) were killed to provide carcass compositions. L-Carnitine had no effect (P > 0.10) on growth, percentages of carcass CP and lipid, or daily protein accretion. However, daily lipid accretion tended to decrease and then return to values similar to those for control pigs (quadratic P < 0.10) with increasing dietary L-carnitine. In Exp. 2, 96 crossbred pigs (initially 34.0 kg BW) were used to investigate the effect of increasing dietary L-carnitine in growing-finishing pigs. Pigs (48 barrows and 48 gilts) were blocked by weight and sex in a randomized complete block design (two pigs/pen and eight pens/treatment). Dietary L-carnitine replaced cornstarch in the control diet to provide 25, 50, 75, 100, and 125 ppm in grower (34 to 56.7 kg; 1.0% lysine) and finisher (56.7 to 103 kg; 0.80% lysine) diets. At 103 kg, one pig/pen was slaughtered, and standard carcass measurements were obtained. Dietary L-carnitine did not influence growth performance (P > 0.10). However, increasing dietary carnitine decreased average and tenth-rib back-fat (quadratic, P < 0.10 and 0.05), and increased percentage lean and daily CP accretion rate (quadratic, P < 0.05). Break point analysis projected the optimal dosage to be between 49 and 64 ppm of L-carnitine for these carcass traits. It is concluded that dietary carnitine fed during the nursery or growing-finishing phase had no effect on growth performance; however, feeding 49 to 64 ppm of L-carnitine during the growing-finishing phase increased CP accretion and decreased tenth-rib backfat.

Influence of dietary carnitine in growing sheep fed diets containing non-protein nitrogen.

The influence of supplemental L-carnitine was investigated in growing sheep fed rations containing non-protein nitrogen (NPN). The experiment was conducted as a randomized block design with a 2x2 factorial arrangement of treatments. Lambs (77.4kg BW, n=24) were fed a total mixed ration (12.1-13.6% CP) with two levels of L-carnitine (0 or 250ppm) and two levels of NPN (urea contributing 0 or 50% of total dietary N) for a 50-day period. Jugular blood samples were collected at 0, 1, and 3h post-feeding, and ruminal fluid samples were collected at 1h post-feeding, during days 1, 8, 29, and 50 of the experiment. Average daily gain (121 versus 214g) was lower (P<0.0001) in lambs fed the NPN diets. Lambs consuming diets containing NPN had higher (P<0.0001) ruminal fluid pH (6.6 versus 5.9), ruminal ammonia N (4.8 versus 2.8mmol/l), and plasma ammonia N (177.1 versus 49.5µmol/l) than lambs not fed NPN. Additionally, lambs fed the NPN diets had lower plasma urea N (14.5 versus 17.5mmol/l; P<0.003) and thyroxine (T(4)) concentrations (65.8 versus 78.4ng/ml; P<0.02), and lower T(4):triiodothyronine (T(3)) ratio (37.9 versus 43.9; P<0.02). Plasma glucose concentrations were higher (P<0.05) in lambs fed L-carnitine (3.83 versus 3.70mmol/l). Two oral urea load tests (OULT 1 and OULT 2) were conducted during the 50-day trial. Urea solutions (0.835g/kg(0.75) BW) were administered as oral drenches. During the OULT 1 (day 10), plasma ammonia N and glucose concentrations were highest (P<0.0001) in the lambs fed NPN with L-carnitine compared with lambs fed control, L-carnitine, and NPN diets. During the OULT 2 (day 50), plasma ammonia N was highest (P<0.0001) in the NPN and NPN with L-carnitine groups compared with the control and L-carnitine groups. Plasma glucose was lowest (P<0.04) in the NPN with L-carnitine group compared with the NPN and L-carnitine groups, but did not differ (P>0.10) from the control group. Plasma urea N levels in both OULT 1 and OULT 2 were lower (P<0.0001) in the NPN and NPN with L-carnitine groups compared with the control and L-carnitine groups. In the present experiment, production and plasma criteria were affected by NPN incorporation in the diets. Production criteria were not affected by inclusion of L-carnitine in the diet, however, L-carnitine reduced experimentally induced hyperammonemia by day 50 of the trial.

Dietary L-carnitine suppresses mitochondrial branched-chain keto acid dehydrogenase activity and enhances protein accretion and carcass characteristics of swine.

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.

Effects of modified tall oil and creatine monohydrate on growth performance, carcass characteristics, and meat quality of growing-finishing pigs.

The effects of feeding modified tall oil (MTO) and creatine monohydrate (CMH) on growing-finishing pig growth performance, carcass characteristics, and meat quality were determined. Eighty cross-bred barrows (initially 45.4 kg) were allotted randomly to one of four dietary treatments by weight and ancestry. The experiment was arranged as a 2 x 2 factorial with two levels of MTO (0 or 0.50%), which were fed throughout the growing-finishing period, and two levels of CMH (0 or 25 g/d), which were fed for the final 10 d before slaughter. The corn-soybean meal diets were fed in two phases (45.4 to 78.9 kg and 78.9 to 117.5 kg BW). When CMH was added to the diet in place of corn, average BW was 107.5 kg. Feeding MTO increased (P < 0.05) ADG and gain:feed ratio (G/F) during the 45.4- to 78.9-kg growth interval and tended to improve (P = 0.10) G/F during the 45.4- to 107.5-kg growth interval. Dietary treatment did not affect (P > 0.15) growth performance during the 78.9- to 107.5-kg growth interval. Modified tall oil increased (P = 0.02) G/F during the 10-d CMH supplementation period, and CMH numerically (P = 0.11) increased ADG and G/F. Supplementation of CMH did not affect (P > 0.20) any measured carcass characteristic or measures of meat quality at 24 h or 14 d postmortem. Feeding MTO reduced average back-fat (P = 0.05) and 10th rib backfat (P = 0.01) but did not affect (P > 0.10) other measured carcass characteristics or measures of meat quality at 24 h postmortem. Modified tall oil increased (P = 0.02) L* values (lightness) and tended to increase (P < 0.10) thawing and cooking losses of longissimus muscle chops at 14 d postmortem. These data demonstrate that MTO improves growth performance and reduces backfat in growing-finishing pigs, but supplementation of CMH, under the conditions of this experiment, was not beneficial for growing-finishing pigs.

Effects of L-carnitine fed during gestation and lactation on sow and litter performance.

Multiparous sows (n = 307) were used to evaluate the effects of added dietary L-carnitine, 100 mg/d during gestation and 50 ppm during lactation, on sow and litter performance. Treatments were arranged as a 2 (gestation or lactation) x2 (with or without L-carnitine) factorial. Control sows were fed 1.81 kg/d of a gestation diet containing .65% total lysine. Treated sows were fed 1.59 kg/d of the control diet with a .23 kg/d topdressing of the control diet that provided 100 mg/d of added L-carnitine. Lactation diets were formulated to contain 1.0% total lysine with or without 50 ppm of added L-carnitine. Sows fed 100 mg/d of added L-carnitine had increased IGF-I concentration on d 60 (71.3 vs. 38.0 ng/mL, P<.01) and 90 of gestation (33.0 vs. 25.0 ng/mL, P = .04). Sows fed added L-carnitine had increased BW gain (55.3 vs 46.3 kg; P<.01) and last rib fat depth gain (2.6 vs. 1.6 mm; P = .04) during gestation. Feeding 100 mg/d of added L-carnitine in gestation increased both total litter (15.5 vs. 14.6 kg; P = .04) and pig (1.53 vs 1.49 kg; P<.01) birth weight. No differences were observed in pig birth weight variation. Added L-carnitine fed during gestation increased litter weaning weight (45.0 vs. 41.3 kg, P = .02); however, no effect of feeding L-carnitine during lactation was observed. No differences were observed in subsequent days to estrus or farrowing rate. Compared to the control diet, feeding added L-carnitine in either gestation, lactation, or both, increased (P<.05) the subsequent number of pigs born alive, but not total born. In conclusion, feeding L-carnitine throughout gestation increased sow body weight and last rib fat depth gain and increased litter weights at birth and weaning.

Effects of L-carnitine fed during lactation on sow and litter performance.

Sows of differing parities and genetics were used at different locations to determine the effects of feeding added L-carnitine during lactation on sow and litter performance. In Exp. 1, sows (n = 50 PIC C15) were fed a lactation diet (1.0% total lysine, .9% Ca, and .8% P) with or without 50 ppm of added L-carnitine from d 108 of gestation until weaning (d 21). No differences in litter weaning weight, survivability, sow ADFI, or sow weight and last rib fat depth change were observed. Number of pigs born alive in the subsequent farrowing were not different (P>.10). In Exp. 2, parity-three and -four sows (n = 115 Large White cross) were used to determine the effect of feeding 0, 50, 100, or 200 ppm of added L-carnitine during lactation (diet containing .9% total lysine, 1.0% Ca, and .8% P) on sow and litter performance. No improvements in the number of pigs or litter weights at weaning were observed (P>.10). Sows fed added L-carnitine had increased weight loss (linear; P<.04), but no differences (P>.10) were observed in last rib fat depth change or subsequent reproductive performance. In Exp. 3, first-parity sows (n = 107 PIC C15) were fed a diet with or without 50 ppm of added L-carnitine during lactation (diet containing 1.0% total lysine). Sows fed added L-carnitine tended (P<.10) to have fewer stillborn and mummified pigs than controls (.42 vs .81 pigs). No differences were observed for litter weaning weight, survivability, or subsequent farrowing performance. Feeding 50 to 200 ppm of added L-carnitine during lactation had little effect on sow and litter performance.

Evaluation of spray-dried animal plasma and select menhaden fish meal in transition diets of pigs weaned at 12 to 14 days of age and reared in different production systems.

We conducted two experiments with pigs weaned at 12 to 14 d of age to evaluate the effects of adding spray-dried animal plasma (SDAP) and select menhaden fish meal (SMFM) to the diets fed from 5 to 19 (Exp. 1) and 7 to 21 d (Exp. 2) after weaning. This 14-d period represents the transition from the nutrient-dense diet fed to all pigs after weaning to the simpler corn-soybean meal-based diet fed to all pigs for an additional 14 (Exp. 1) or 7 d (Exp. 2) after the experimental period. Pigs averaged 5 kg at the start of the experimental period. In Exp. 1, pigs had a high health status and were weaned to an off-site nursery (SEW) and fed 12 experimental diets in a 3 (0, 2.5, or 5% SDAP) x 4 (0, 2.5, 5, or 7.5% SMFM) factorial arrangement. Diets were formulated to contain 1.6% lysine and contained 20% dried whey, 5% soybean oil, and 2.5% spray-dried blood meal. The SDAP and(or) SMFM replaced corn and soybean meal on an equal lysine basis. Average daily gain and ADFI were not affected by treatment during any period of the experiment. Gain:feed was improved by the addition of SDAP (linear, P < .05) and SMFM (linear, P < .07) during the period from 5 to 19 d. Over the 33-d experiment, SDAP and SMFM improved (linear, P < .05) gain:feed. In Exp. 2, pigs were weaned on-site to an all-in/all-out by room nursery and fed diets identical to those fed in Exp. 1, with 0 or 2.5% SDAP and 0, 2.5, or 5% SMFM in a 2 x 3 factorial arrangement. The addition of 2.5% SDAP improved ADG and gain:feed during the period from 7 to 14 d (P < .05) and 0 to 28 d (P < .10), but not over the period from 7 to 21 d. The addition of SMFM did not affect ADG during any period, but it resulted in a quadratic improvement in gain:feed during the periods from 7 to 14 (P < .05) and 7 to 21 (P < .10) d. These results suggest that high-health SEW pigs respond less to SDAP and SMFM in the transition diet than pigs with a lower health status reared in an on-site nursery. The data further suggest that formulation of transition diets should consider the type of production system if pig performance and diet cost are to be optimized.

Influence of weaning age and nursery diet complexity on growth performance and carcass characteristics and composition of high-health status pigs from weaning to 109 kilograms.

We examined the influence of weaning age (9 or 19 +/- 1 d) and nursery diet complexity on growth performance and carcass composition of 192 high-health status barrows from weaning to 109 kg. Pigs were fed diets of different complexity (high, medium, or low) in various regimens from weaning to 18.7 kg. They then were fed common corn-soybean meal-based diets from 18.7 to 109 kg. Increasing diet complexity improved ADG from weaning to 7.0 kg (P < .10) but had no effect (P > .10) from 7.0 to 18.7 kg. Thus, increasing diet complexity seems to improve ADG only in the early period after weaning. Age at 109 kg was similar (P > .10) for the pigs weaned at 9 and 19 d. However, pigs fed the medium-complexity regimens were the youngest (P < .01) at 109 kg. Interactions (P < .06) were observed for carcass lipid and lipid:protein accretion from 18.7 to 109 kg. These were the result of pigs weaned at 9 d of age having higher carcass lipid and lipid:CP accretion rates when fed the low-complexity regimens than when fed the medium- or high-complexity regimens. However, pigs weaned at 19 d of age had similar carcass lipid and lipid:protein accretion ratios regardless of diet complexity. When health status was similar, growth performance was similar between weaning ages but was influenced by diet complexity. Carcass lipid and lipid:protein deposition ratios increased when simple regimens were fed to pigs weaned at 9 d of age in the subsequent growing-finishing period.

Effect of L-carnitine and soybean oil on growth performance and body composition of early-weaned pigs.

Two experiments were conducted to evaluate the effect of dietary L-carnitine on growth performance and body composition of early-weaned pigs. In Exp. 1, 120 weanling pigs (initially 5.6 kg and 19 +/- 2 d of age) were allotted in a 3 x 2 factorial with four pigs per pen and five replications (pens) per treatment. Main effects from d 0 to 14 after weaning included dietary L-carnitine (0, 500, or 1,000 ppm) and soybean oil (0 to 10%). From d 14 to 35 after weaning, levels were reduced to 0, 250, or 500 ppm L-carnitine and 0 or 5% soybean oil. No L-carnitine x soybean oil interactions were observed (P > .10). From d 0 to 14, L-carnitine and soybean oil had no effect (P > .10) on pig performance. From d 14 to 35 and d 0 to 35, gain:feed ratio (G/F) improved (linear, P < .05) with increasing dietary L-carnitine; however, ADG and ADFI were not affected. Soybean oil improved ADG and G/F (P < .05) from d 14 to 35 and ADG from d 0 to 35. In Exp. 2, 180 weanling pigs (initially 6.0 kg and 22 +/- 2 d of age) were allotted in a 2 x 3 factorial. Pigs were fed either 0 or 1,000 ppm L-carnitine from d 0 to 14 after weaning and then pigs fed each of these diets were fed diets containing 0, 250, or 500 ppm L-carnitine from d 14 to 35. No interactions occurred between feeding L-carnitine from d 0 to 14 and performance observed from d 14 to 35. From d 0 to 14 after weaning, L-carnitine increased ADG (P < .08) and ADFI (P < .02). From d 14 to 35, ADFI decreased (linear, P < .05) and G/F increased (quadratic, P < .05) as dietary L-carnitine increased. Cumulative (d 0 to 35) ADFI decreased (linear, P < .05) and G/F increased (linear, P < .05) with increasing L-carnitine. On d 35, 14 pigs from each of four selected treatments (0 or 1,000 ppm L-carnitine from d 0 to 14 followed by either 0 or 500 ppm from d 14 to 35) were slaughtered, and carcass composition was recorded. Carcass moisture and CP percentages were not influenced (P > .10) by dietary L-carnitine. However, pigs fed 1,000 ppm L-carnitine from d 0 to 14 had less (P < .05) carcass lipid and daily lipid accretion on d 35 whether they were fed L-carnitine from d 14 to 35 or not. These results suggest that dietary L-carnitine improves G/F and reduces carcass lipid accretion in early-weaned pigs.

Influence of lipopolysaccharide-induced immune challenge and diet complexity on growth performance and acute-phase protein production in segregated early-weaned pigs.

Segregated early-weaned pigs (initially 4.0 kg and 14 +/- 1.5 d of age) were used to quantify the effects of lipopolysaccharide (LPS)-induced immune challenge and nursery diet complexity (complex, medium, and simple) on growth performance and haptoglobin production. Three treatments of immune challenge consisted of pigs given ad libitum access to feed (control), challenged with LPS and given ad libitum access to feed (LPS-challenged), or pair-fed to receive the same amount of feed as the LPS-challenged pigs (pair-fed). The absence of interactions (P > .10) between diet complexity and immune challenge with LPS indicated that the responses were independent. Control pigs were the heaviest (P < .01), LPS-challenged the lightest (P < .01), and pair-fed intermediate in weight on d 18 after weaning. Approximately two thirds of the decreased growth of LPS-challenged pigs was due to decreased ADFI and one third was due to decreased feed efficiency (G/F). Pigs fed the complex diet were heaviest (P < .05), and pigs fed the simple diet were lightest (P < .05) on d 18 after weaning. The increased growth of pigs fed the complex compared with those fed the medium diet was due to the increased ADFI of the former. The decreased growth of pigs fed the simple diet compared with those fed the medium or complex diets was due to both decreased ADFI and G/F. The LPS-challenged pigs had increased (P < .01) haptoglobin concentrations, suggesting that inflammatory cytokine production was higher in immune-challenged pigs. These data suggest that LPS immune challenge caused decreased growth by decreasing ADFI and altering nutrient partitioning and that growth responses to diet complexity are independent of immune challenge.

The effect of dietary methionine and its relationship to lysine on growth performance of the segregated early-weaned pig.

Two experiments were conducted to determine the dietary methionine requirement and the appropriate methionine:lysine for the segregated early weaned-weaned pig. In Exp. 1, 435 crossbred pigs (9.5 +/- 4 d of age and 3.5 kg BW) were fed diets (1.8% lysine, .62% cystine) containing 10% spray-dried plasma protein (SDPP) and 1.75% spray-dried blood meal (SDBM) from day 0 to 21 postweaning. Pigs were feed one of six dietary treatments from .36% to .56% total dietary methionine (.317 to .517% apparent digestible methionine). From d 0 to 7 and d 0 to 21 postweaning, ADG and gain:feed ratio (G/F) increased (linear, P < .01, P < .05, respectively) as dietary methionine increased. In Exp. 2, 350 crossbred pigs (9.0 +/- 2 d of age and 3.8 kg BW) were used to determine the appropriate methionine:lysine ratio for the segregated early-weaned pig in a 2 x 5 factorial arrangement. Two lysine levels (1.8 and 1.4%) and five methionine levels within each lysine level were used to obtain methionine:lysine ratios ranging from 21.5 to 33.5%. From d 0 to 21 postweaning, pigs were assigned to one of 10 dietary treatments containing 25% dried whey, 12% lactose, 7.5% SDPP, 6.0% select menhaden fish meal, and 1.75% SDBM. No methionine x lysine interactions were observed (P > .10). From d 0 to 7 postweaning, increasing dietary methionine improved (quadratic, P < .01) ADG and ADFI regardless of dietary lysine. From d 0 to 14 postweaning, increasing dietary methionine improved ADG (quadratic, P < .01), ADFI quadratic, P =.02), and G/F (quadratic, P < .10). Inflection point analysis projected maximum ADG at methionine:lysine ratios of 27 and 27.5% for pigs fed 1.4 and 1.8% lysine, respectively. Cumulative (d 0 to 21 postweaning) ADG, ADFI, and G/F were improved (quadratic, P < .05) by increasing dietary methionine. Increasing dietary lysine improved (P < .01) ADG and G/F from d 0 to 7, from d 0 to 14, and for the overall experiment. In conclusion, a diet with 1.8% total lysine that includes spray-dried blood products must contain .48 to .52% total dietary methionine (.437 to .477% apparent digestible) or 27.5% of total lysine to maximize growth performance of pigs from d 0 to 21 postweaning (3.5 to 12 kg BW).

Added dietary methionine in starter pig diets containing spray-dried blood products.

Two experiments were conducted to determine the dietary methionine requirement of weanling pigs fed diets containing spray-dried porcine plasma and(or) blood meal in a phase-feeding program. In Exp. 1, 216 crossbred pigs (21 +/- 2 d of age and 4.9 kg BW) were fed diets (1.6% lysine, .52% cystine) containing 10% spray-dried porcine plasma and 1.75% spray-dried blood meal from d 0 to 21 postweaning. Pigs were fed one of six dietary treatments ranging from .28 to .48% total dietary methionine (.225 to .425% apparent digestible methionine). From d 0 to 14 and d 0 to 21 postweaning, ADG, ADFI, and gain:feed ratio (G:F) increased (quadratic, P < .01) as dietary methionine increased. Inflection point analysis projected .42 and .41% total dietary methionine to maximize ADG and G:F from d 0 to 14 and d 0 to 21 postweaning, respectively. In Exp. 2,216 crossbred pigs (21 +/- 3 d of age and 5.6 kg BW) were used to determine the dietary methionine requirement from d 7 to 28 postweaning. All pigs were fed the same diet (1.6% lysine, .44% methionine, .52% cystine) from d 0 to 7 postweaning. From d 7 to 28, pigs were assigned to one of six dietary treatments (1.3% lysine, .46% cystine) containing 10% dried whey and 3% spray-dried blood meal. Total dietary methionine levels ranged from .27 to .42% (.249 to .399% apparent digestible methionine). From d 7 to 14 postweaning, increasing dietary methionine increased (quadratic, P < .05) ADG, ADFI, and G:F (.34 to .35% total methionine projected by inflection point analysis).(ABSTRACT TRUNCATED AT 250 WORDS)

Self-selection of diets and lysine requirements of growing-finishing swine.

A growth trial using 240 growing-finishing pigs (22 to 109 kg) was conducted to determine whether pigs offered a choice of low- and high-lysine sorghum-soybean meal diets can select the correct proportion of each to optimize performance and carcass leanness. Pigs on the choice treatments could select from two diets offered simultaneously in identical feeders. In two of the choice treatments, pigs had access only to the low-lysine diet for the first 2 d of each 21-d period to determine whether forced adaptation to the low-lysine diet would alter the proportion of diets selected. These were termed the adjusted treatments. The choice treatments were 1) .50 or 1.10% lysine, 2) .50 or 1.60% lysine, 3) same as 1 but adjusted, and 4) same as 2 but adjusted. Five additional treatments were arranged as a titration study to determine the lysine requirement of the pigs. The dietary lysine levels needed in sorghum-soybean meal diets to optimize performance and carcass leanness of barrows and gilts were .95, .80, and .70% lysine for the 22 to 52, 52 to 78, and 78 to 109 kg weight intervals, respectively. Lysine intake of pigs on the choice treatments exceeded the amounts needed to maximize performance and carcass leanness. The adjustment practice lowered lysine intake, but intake was still excessive. Percentage of lean and gain/feed were less desirable for the choice treatments than for pigs fed the .95-.80-.70% lysine treatment. These reductions, plus the higher lysine intakes, indicate that the choice treatments used in this research are not feasible for commercial swine production.

Digestible threonine requirements of starter and finisher pigs.

The digestible threonine (Thr) requirements of starter (28 d of age initially, 6 to 16 kg) and finisher (58 to 96 kg) pigs were determined. Each growth trial evaluated control and basal diets and the basal diet plus four incremental additions of L-Thr (.60 to .76% dietary Thr for starter pigs and .30 to .50% dietary Thr for finisher pigs). The basal diet fed to starter pigs contained 17.6% CP and 1.25% lysine and was based on sorghum, peanut meal, soybean meal, and dried whey. The basal diet fed to finisher pigs contained 9.7% CP and .75% lysine and was based on sorghum supplemented with lysine, methionine, tryptophan, and isoleucine. Incremental increases in dietary Thr increased (P < .05) ADG and ADFI of starter pigs quadratically. Gain/feed increased (P < .01) linearly. Based on broken-line regression analyses, .63% Thr maximized ADG of starter pigs. Daily gain and gain/feed of finisher pigs increased linearly (P < .01) and quadratically (P < .01) as dietary Thr content increased. Broken-line regression analyses determined that .41% Thr maximized ADG and gain/feed. Digestion trials with pigs fitted with an ileal T-cannula determined that the basal starter and finisher diets contained .43 and .17% apparent ileal digestible Thr and 3.35 and 3.38 Kcal of fecal DE/g, respectively. On average, crystalline Thr had an apparent ileal digestibility of 98%. Based on these values and the total Thr requirements given above, the digestible Thr requirement of finisher pigs for maximum ADG and gain/feed was estimated to be .28%.(ABSTRACT TRUNCATED AT 250 WORDS)