QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ramanau, A. Articles by Eder, K. Search for Related Content PubMed PubMed Citation Articles by Ramanau, A. Articles by Eder, K.

---

Nutrient Requirements

Supplementation of Sows with L-Carnitine during Pregnancy and Lactation Improves Growth of the Piglets during the Suckling Period Through Increased Milk Production

Institute of Nutritional Sciences and ^* Biometrics and Informatics in Agriculture Group, Martin-Luther University, Halle-Wittenberg, D-06108 Halle/Saale, Germany

¹To whom correspondence should be addressed. E-mail: eder{at}landw.uni-halle.de.

	ABSTRACT

TOP ABSTRACT MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 
Recent studies showed that piglets of sows fed diets supplemented with L-carnitine grow faster during the suckling period than piglets of control sows fed diets without L-carnitine. This study was undertaken to investigate the effect of L-carnitine supplementation in sows on milk production and milk constituents. An experiment was performed in which two groups of 20 gilts each were fed diets with or without supplemental L-carnitine during pregnancy (0 vs. 125 mg L-carnitine daily/sow) and lactation (0 vs. 250 mg L-carnitine daily/sow). The experiment was continued over two reproductive cycles. L-carnitine–treated sows had larger litters (P < 0.01) and higher litter weights (P < 0.05) than control sows. Piglets of L-carnitine–treated sows had lower birth weights (P < 0.05) but grew faster during the suckling period (P < 0.01) and were heavier (P < 0.05) at weaning than piglets of control sows. L-Carnitine–treated sows had higher milk yields on d 11 and 18 of lactation than control sows (P < 0.05). Milk of L-carnitine–treated sows had higher concentrations of total and free carnitine than milk of control sows (P < 0.001); concentrations of fat, protein and lactose and the amounts of gross energy in the milk did not differ between the two groups of sows. The amounts of protein (P < 0.05) and lactose (P < 0.05) were higher in L-carnitine–treated sows than in control sows; the amount of energy secreted with the milk tended to be higher in carnitine-treated sows than in control sows (P < 0.10). The study suggests that piglets of carnitine-treated sows grow faster during the suckling period than those of control sows because they ingest more nutrients and energy with the milk.

KEY WORDS: • L-carnitine • sows • piglets • milk

Recent studies showed that supplementing sow diets with L-carnitine during pregnancy and lactation increases birth weights of piglets (1–3). Moreover, piglets of sows fed diets supplemented with L-carnitine grew faster during the suckling period than piglets of control sows (2,3). The reasons for these effects are largely unknown. The growth of piglets after birth is determined primarily by the supply of nutrients with the milk, which is their only source of food during the first few days of life (4). We therefore suspect that faster growth of piglets from sows supplemented with L-carnitine during suckling might be due to increased milk production or higher nutrient levels in the milk. This study was designed to investigate the effect of dietary L-carnitine supplementation of sows on milk production and concentrations of various nutrients in the milk. Milk production depends on the sow’s nutritional status (5) but can also be affected by the suckling behavior of her piglets. Piglets suckling more frequently stimulate increased milk secretion and consequently have a higher total milk intake (6,7). To determine whether dietary L-carnitine supplementation of sows influences the suckling behavior of piglets, we measured the number of sucklings, the intervals between sucklings and the total time spent suckling in a day. Because newborn piglets can synthesize L-carnitine only to a small extent, the milk is an important source of L-carnitine. Therefore, we also determined the concentrations of L-carnitine in the milk.

	MATERIALS AND METHODS

TOP ABSTRACT MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 
    Animals. Crossbred gilts (German land race x Large white; n = 40) with a mean (±SEM) body weight of 144 ± 2 kg, acquired from a local breeder, were assigned to two groups of 20 pigs each. Their sexual cycle was synchronized by oral administration of 20 mg Altrenogest/d (Regumate, Hoechst Roussel, Frankfurt, Germany). The sows were artificially inseminated with sperm from Pietrain boars. Sows who failed to conceive were removed from the experiment. After weaning, the trial continued for a second reproductive cycle.

    Housing. The sows were kept in single crates until d 30 of pregnancy. From d 30 to 110 of pregnancy, the sows were kept in groups of eight in pens measuring 45 m² that had fully slatted floors, nipple drinkers and electronic feeding stations. On d 110 of pregnancy, they were moved to the farrowing accommodation where they were housed in single farrowing pens. Before farrowing rubber mats were put down as a surface for the piglets to lie on. An infrared heater was suspended above each rubber mat to keep the temperature for the newborn piglets at a constant 35°C. The climate in the dry sow accommodation and the farrowing unit was maintained at a temperature of 19 ± 2°C and 60–80% relative humidity by means of an air conditioning system. A light:dark cycle (12-h light:12-h dark) was applied. All animal procedures described followed established guidelines for the care and handling of laboratory animals and were approved by the regional council of Saxony-Anhalt.

    Diets and feeding. Two commercial sow diets were used. The first diet, fed from the start of the experiment until d 110 of pregnancy ("gestation diet," Turbo Sauenfutter Soft pell, Kraftfutterwerk Niederpöllnitz, Niederpöllnitz, Germany), consisted of (g/kg diet): wheat bran (300), alfalfa meal (250), triticale (138), molassed dried sugar beet pulp (120), barley (77), peas (20), extracted sunflower meal (50), rapeseed cake (13), molasses (20) and premix including minerals, vitamins and L-lysine (12). The second diet, fed from d 111 of pregnancy until weaning ("lactation diet," Porfinal, Deuka, Düsseldorf, Germany) consisted of (g/kg diet): wheat (322), barley (220), wheat bran (180), soy bean meal (140), peas (50), wheat gluten (30), extracted soy bean oil (24) and premix including minerals and vitamins (34). Concentrations of nutrients in the diets are shown in Table 1. The gestation and lactation diets contained 16 and 4 mg L-carnitine/kg, respectively. From the beginning of the experiment until d 30 of pregnancy the sows were offered 3.0 kg of gestation diet/d; from d 30 to 110 the diet was consumed ad libitum. From d 110 to farrowing each sow was fed 2.5 kg of the lactation diet. On the day of farrowing, the sows were fed 1.5 kg, which was then successively increased (3 kg/d on d 1 and 2 of lactation; 4.5 kg/d on d 3 and 4 of lactation; ad libitum consumption from d 5 of lactation to weaning). From weaning until the second insemination, the sows were fed 2.5 kg gestation diet/d. Sows in the treatment group were supplemented with 125 mg L-carnitine/d during pregnancy and 250 mg L-carnitine/d during lactation. L-Carnitine was supplied as tablets containing L-carnitine (125 mg/tablet, supplied by Lohmann Animal Health, Cuxhaven, Germany), lactose and dextrose. During pregnancy, the tablets were administered once daily; during lactation, tablets were administered twice daily, at 0900 and 1600 h. Control pigs were given the same tablets without L-carnitine. Water was provided by nipple drinking systems. The piglets were offered a creep feed (Deuka Primo Wean, Deuka) from d 19 of lactation until weaning. The creep feed contained (per kg): 15.6 MJ metabolizable energy, 200 g crude protein, 85 g crude fat, 25 g crude fiber and 60 g crude ash; the carnitine concentration was <5 mg/kg.

    Determination of milk output. Milk output was determined on d 11 and 18 of lactation in 13 of the 16 sows of each group in the first lactation and in the 10 of the 13 sows of each group in the second lactation. To eliminate the effect of litter size on milk production, the litter size of these sows was standardized to 10 piglets/litter within 2 d of farrowing. Piglets were removed from sows having >10 piglets and placed with sows of the same group having <10 piglets. Piglets taken away from sows as well as piglets added to sows were selected on the basis of their body weights. It was intended to adjust the average weights of piglets of each individual sow after litter standardization to those before litter standardization. Surplus piglets were nursed by the remaining three sows of each group that were not being used for milk output determination. Piglets that dropped out before d 18 of lactation were immediately replaced by equivalent piglets with similar body weights that had previously been nursed by the remaining control or treated sows. The milk output was measured by the "weigh-suckle-weigh" method (8). On the day of the milk recording procedure, the piglets were separated from the sow by means of a barrier from 0600 to 1600 h and allowed supervised access to the sow only at 1-h intervals for the duration of suckling. The first two weighings (0700 and 0800 h) were done to allow sow and piglets to become accustomed to the procedure; the calculation of the daily milk production was based on the last seven measurements. To minimize losses through feces and urine, the piglets were weighed rapidly; the accuracy of the scales was ±1 g.

    Analysis of milk constituents. On d 11 of the lactation, after termination of milk output determination, the sows were given 15 IU oxytocin (Atarost, Twistringen, Germany) by i.m. injection; 80–100 mL of milk was expressed manually from all active teats of each sow. The concentration of lactose in the milk was determined using an enzymatic kit reagent from Boehringer (Mannheim, Germany, Cat-No. 0176303); the concentration of protein in the milk was determined using the Kjehldahl method of the IDF-ISO-AOAC (9); the concentration of fat in the milk was determined by ether extraction (9). The energy content of the milk was calculated from the concentrations of protein, fat and lactose; the following energy concentrations were used: lactose, 16.4 kJ/g; fat, 38.9 kJ/g; protein, 23.8 kJ/g. Amounts of fat, protein, lactose and energy secreted with the milk on d 11 of lactation were calculated by multiplying the daily milk yield by the concentrations of these nutrients or energy, respectively, in the milk. The fatty acid composition of the milk fat was determined by extracting lipids with hexane-isopropanol (3:2, v/v) (10) and transmethylation by means of trimethyl sulfonium hydroxide (11). The resulting FAME were separated by capillary GC (12). The concentrations of total carnitine in the diets and of total, free and esterified carnitine in the milk were determined by a radiochemical method, which is based on the conversion of carnitine into [³H]acetylcarnitine by carnitine-O-acetyltransferase (13).

    Determination of piglet suckling times. On d 3 of the second lactation, four sows from each of the two groups and their litters were filmed over a 24-h period with a video camera. The videotapes were viewed. The number of sucklings was counted and their mean duration and the total suckling time measured with a stop-watch.

    Statistics. The statistical analysis of the data was performed with the SAS package (procedure mixed, version 8.2, SAS Institute, Cary, NC). A mixed linear model with three fixed effects, two random effects and, depending on the trait under investigation, one covariable was used. Treatment (control, L-carnitine), reproductive cycle and the interaction between these factors were included as fixed effects. Because the same sows were used over two reproductive cycles the observations within one sow were repeated measurements. Thus, in addition to the random error effect, a random sow effect was included. Body weights of the piglets at birth were additionally analyzed with litter size as a covariable. For estimation of the variance of the random effects, the restricted maximum likelihood (REML) method was used (14). The standard errors of the estimated fixed effects and their linear combination to least-square means (LS means) as well as the df for estimates and hypothesis tests, respectively, were calculated according to Kenward and Roger (15). Values in the text are LS mean ± SE. Differences were considered significant if P < 0.05.

	RESULTS

TOP ABSTRACT MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 
    Number of pregnant sows. In the first cycle, 16 of the 20 sows in each group conceived; in the second cycle, 13 of the 16 sows in each group conceived.

    Diet intake, body weights of the sows and backfat thickness. Diet intakes of the sows from d 1 to 110 of pregnancy and during lactation were higher in the second than in the first cycle (Table 2). L-Carnitine supplementation did not influence diet intake from d 1 to 110 of pregnancy but did increase diet intake during lactation. Body weights of the sows on d 1, 85 and 110 of pregnancy and at weaning were higher in the second cycle than in the first cycle; L-carnitine supplementation did not affect the sows’ body weights. Backfat thickness was also unaffected by L-carnitine supplementation. However, backfat thickness of the sows on d 110 of pregnancy and at weaning was significantly higher in the second cycle than in the first cycle.

    Creep feed intake of piglets. Creep feed intake did not differ in piglets of control sows and piglets of sows treated with L-carnitine. Piglets of control sows and sows treated with L-carnitine, born in the first reproductive cycle consumed 172 ± 5 and 178 ± 7 g creep feed, respectively, from d 19 to weaning on d 25 (n = 13); piglets of control sows and sows treated with L-carnitine, born in the second cycle consumed 528 ± 16 and 504 ± 14 g creep feed, respectively, from d 19 to weaning on d 30 (n = 10).

    Weight gains of piglets during suckling. Piglets born in the second reproductive cycle grew faster during the suckling period than piglets born in the first cycle (Table 4).

    Milk production, milk constituents and amounts of nutrients secreted in the milk. Sows produced more milk in the second cycle than in the first cycle, on both d 11 and 18 of lactation (Table 5). Sows supplemented with L-carnitine produced more milk on d 11 and 18 of lactation than control sows. This effect was evident in both lactations.

    Fatty acid composition of milk total lipids. The fatty acid composition of total lipids, measured in the milk on d 11 of the second lactation, did not differ between the two groups of sows (data not shown). Palmitic acid (29.2 ± 0.7 g/100 g total fatty acids), oleic acid (33.9 ± 1.2 g/100 g total fatty acids) and linoleic acid (13.9 ± 0.3 g/100 total fatty acids, n = 26) made up the quantitatively largest amounts of fatty acids in the milk. The amounts of total saturated, monounsaturated and polyunsaturated fatty acids were 39.5 ± 0.9, 42.9 ± 0.9 and 17.2 ± 0.3 g/100 g total fatty acids, respectively, in the milk of control sows and 39.8 ± 0.6, 42.3 ± 2.4 and 17.5 ± 0.3 g/100 g total fatty acids, respectively, in the milk of sows treated with L-carnitine (n = 13).

    Carnitine concentration in milk. The milk of sows in the first lactation had higher concentrations of total and free carnitine than in the second lactation; the concentration of esterified carnitine in the milk did not differ between the first and the second lactations (Table 6). The milk of sows treated with L-carnitine had higher concentrations of total and free carnitine; the concentration of esterified carnitine in the milk did not differ between the two groups of sows.

	DISCUSSION

TOP ABSTRACT MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 
This study was undertaken to investigate the effects of L-carnitine supplementation in sows during pregnancy and lactation on milk production and milk constituents. An experiment was performed over two reproductive cycles. It was not surprising that the sows were heavier and had higher diet intakes, higher litter weights and higher milk production in the second cycle than in the first cycle. Differences in body weights, feed intake capacity, litter weights and milk production between first parity sows and multiparous sows are well documented in the literature (16). Milk production of sows depends largely on the number of nursing piglets. The milk production of the sows and body weight gains of the suckling piglets during the first and second lactation observed in this study are in close agreement with data reported in the literature for sows nursing 10 piglets (17). The milk composition, i.e., the concentrations of protein, fat and lactose in the milk of the sows, also is consistent with literature data (18).

Our work confirms recent studies (1–3) showing that supplementation of sows’ diets with L-carnitine increases reproductive performance. Recent studies reported increased piglet and litter weights at birth in sows fed diets supplemented with L-carnitine (1–3). An increase in the number of piglets born to sows fed L-carnitine–supplemented diets during pregnancy has not yet been observed. However, Musser et al. (19) found that dietary L-carnitine supplementation during lactation increased the number of piglets in the subsequent litter. These observations suggest that dietary L-carnitine either increases the ovulation rate or reduces embryonal mortality in sows. A previous study by Musser et al. (1) showed that dietary L-carnitine increases the concentrations of insulin and insulin-like growth factor-1 in the blood of sows during pregnancy. Because insulin influences ovarian function, follicle development and ovulation rate (20), a relationship may exist among L-carnitine, insulin and ovulation rate. Further studies are required to clarify the effects of L-carnitine on ovarian function, ovulation rate and embryonal mortality in sows. The effect of L-carnitine treatment on the number of piglets born in this study was much larger than one would normally expect. Further studies with a much higher number of sows are required to confirm the effects of L-carnitine on the number of piglets born.

As in previous studies (1–3), piglets of sows supplemented with L-carnitine grew faster during the suckling period than piglets of control sows. Our study suggests that this effect might be due to a higher milk yield and an increased transfer of energy and nutrients from the sow to the piglets with the milk. The main action of L-carnitine in mammals is to transfer long-chain fatty acids through the inner membrane of mitochondria where ß-oxidation occurs (21). However, neither the fat content of the milk nor the fatty acid composition of milk total lipids was affected by dietary L-carnitine. We therefore assume that L-carnitine did not influence the fatty acid metabolism in the mammary gland. Newborn or weanling pigs can synthesize L-carnitine only to a small extent (22,23). An increased concentration of carnitine in the milk of sows treated with L-carnitine could therefore induce more efficient energy utilization in suckling piglets. In weaned piglets, dietary L-carnitine supplementation slightly increased the gain/feed ratio (24) and improved nitrogen retention (25).

Another finding of this study is that dietary L-carnitine increased the secretion of lactose and protein with milk. This supports the concept that both carbohydrate and protein metabolism of pigs may be altered by dietary L-carnitine. Owen et al. (26) observed altered metabolism in growing pigs fed L-carnitine. These researchers observed increased flux through pyruvate carboxylase and decreased flux through branched-chain -keto acid dehydrogenase in liver mitochondria with increasing dietary L-carnitine. These metabolic changes favor gluconeogenesis and reduced oxidation of BCAA that could provide substrate for milk lactose and protein synthesis.

Milk production of sows is influenced by their nutritional status, in particular the energy supply during lactation (5). The increased milk production of sows treated with L-carnitine could therefore be due to the higher diet intake of these sows compared with control sows. In weaned piglets and growing-finishing pigs, dietary L-carnitine enhanced the oxidation of fatty acids from adipose tissue and the accretion of body protein, leading to a higher ratio of body protein to adipose tissue (25–27). The data for body weights and backfat thickness at weaning, which did not differ between L-carnitine treated and control sows, do not suggest enhanced mobilization of adipose tissue by supplemental L-carnitine for milk synthesis. The additional energy required for increased milk production in sows treated with L-carnitine might therefore have been supplied primarily by the diet.

Milk production of sows is also strongly influenced by litter size, piglet weights and suckling intervals (6,7,17,28). If piglets suckle more frequently, they will obtain more milk, thus causing milk production to rise. To study the suckling behavior of the piglets, we filmed four litters of each group of sows over a 24-h period. In this small number of litters, no differences in suckling behavior were observed between the two groups of piglets in terms of the number of sucklings and the total time spent suckling in a day. Litter size did not play a role in the different milk yields of carnitine-treated and control sows because the number of piglets was standardized after birth. It is remarkable that piglets of sows supplemented with L-carnitine gained more body weight during the suckling period although they were initially lighter than piglets of control sows. Normally, piglets that are heavier at birth grow faster during the suckling period because they are able to massage the teats more strongly and therefore obtain more milk at each suckling (28). What we suspect is that piglets of sows supplemented with L-carnitine were more vigorous and despite their lower initial body weights, they were able to stimulate a greater milk flow in the sows than piglets of control sows.

In conclusion, this study confirms that dietary L-carnitine improves the reproductive performance of sows. It also shows that higher growth rates of piglets from sows treated with L-carnitine during the suckling period compared with piglets from control sows are due to an increased supply of nutrients in the milk.

Manuscript received 16 July 2003. Initial review completed 3 September 2003. Revision accepted 17 October 2003.

	LITERATURE CITED

TOP ABSTRACT MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 

1. Musser, R. E., Goodband, R. D., Tokach, M. D., Owen, K. Q., Nelssen, J. L., Blum, S. A., Dritz, S. S. & Civis, C. A. (1999) Effects of L-carnitine fed during gestation and lactation on sow and litter performance. J. Anim. Sci. 77:3289-3295.[Abstract/Free Full Text]

2. Eder, K., Ramanau, A. & Kluge, H. (2001) Effect of L-carnitine supplementation on performance parameters in gilts and sows. J. Anim. Physiol. Anim. Nutr. 85:73-80.[Medline]

3. Ramanau, A., Kluge, H., Spilke, J. & Eder, K. (2002) Reproductive performance of sows supplemented with dietary L-carnitine over three reproductive cycles. Arch. Anim. Nutr. 56:287-296.

4. Williams, I. H. (1995) Sows’ milk as a major nutrient source before weaning. Hennessy, D. P. Cranwell, P. D. eds. Manipulating Pig Production V 1995:71 Australian Pig Science Association Werribee, Victoria, Australia. .

5. Noblet, J., Etienne, M. & Dourmad, J.-Y. (1998) Energetic efficiency of milk production. Verstegen, M.W.A. Moughan, P. J. Schrama, J. W. eds. The Lactating Sow 1998:113 Wageningen Pers Wageningen, The Netherlands. .

6. Auldist, D. E., Morrish, L., Wakeford, C. & King, R. H. (1995) Effect of increased suckling frequency on mammary development and milk yield of sows. Hennessy, D. P. Cranwell, P. D. eds. Manipulating Pig Prioduction V 1995:137 Australian Pig Science Association Werribee, Victoria, Australia. .

7. Spinka, M., Illmann, G., Algers, B. & Stetkova, Z. (1997) The role of nursing frequency in milk production in domestic pigs. J. Anim. Sci. 75:1223-1228.[Abstract/Free Full Text]

8. Kirchgessner, M., Schneider, R. & Paulicks, B. R. (1992) Milchleistung sowie Milchfett- und -energiegehalte bei Sauen mit unterschiedlicher Methioninversorgung. J. Anim. Physiol. Anim. Nutr. 68:244-253.

9. Association of Official Analytical Chemists (1990) Helrich, K. eds. Official Methods of Analysis 15th ed. 1990:802-852 AOAC Arlington, VA. .

10. Hara, A. & Radin, N. S. (1978) Lipid extraction of tissues with a low toxicity solvent, Anal. Biochem 90:420-426.

11. Butte, W. (1983) Rapid method for the determination of fatty acid profiles from fats and oils using trimethylsulfonium hydroxide for transesterification. J. Chromatogr. 261:142-145.

12. Eder, K. & Brandsch, C. (2002) Effect of fatty acid composition of rapeseed oil on plasma lipids, fatty acid composition of tissues and susceptibility of low-density lipoprotein to lipid peroxidation in cholesterol-fed hamsters. Eur. J. Lipid Sci. Technol. 104:3-13.

13. McGarry, J. D. & Foster, D. W. (1976) An improved and simplified radioisotopic assay for the determination of free and esterified carnitine. J. Lipid Res. 17:277-281.[Abstract]

14. Searle, S. R., Casella, G. & McCulloch, C. E. (1992) Variance Components 1992 Wiley New York, NY.

15. Kenward, M. G. & Roger, J. H. (1997) Small sample inference for fixed effects from restricted maximum likelihood. Biometrics 53:983-997.[Medline]

16. Rozeboom, D. W., Pettigrew, J. E., Moser, R. L., Cornelius, S. G. & El Kandelgy, S. M. (1996) Influence of gilt age and body composition at first breeding on sow reproductive performance and longevity. J. Anim. Sci. 74:138-150.[Abstract]

17. Etienne, M., Dourmad, J.-Y. & Noblet, J. (1998) The influence of some sow and piglet characteristics and of environmental conditions on milk production. Verstegen, M.W.A. Moughan, P. J. Schrama, J. W. eds. The Lactating Sow 1998:285-299 Wageningen Pers Wageningen, The Netherlands. .

18. Darragh, A. J. & Mouigha, P. J. (1998) The composition of colostrum and milk. Verstegen, M.W.A. Moughan, P. J. Schrama, J. W. eds. The Lactating Sow 1998:3-21 Wageningen Pers Wageningen, The Netherlands. .

19. Musser, R. E., Goodband, R. D., Tokach, M. D., Owen, K. Q., Nelssen, J. L., Blum, S. A., Campbell, R. G., Smits, R., Dritz, S. S. & Civis, C. A. (1999) Effects of L-carnitine fed during lactation on sow and litter performance. J. Anim. Sci. 77:3296-3303.[Abstract/Free Full Text]

20. Cox, N. M., Stuart, M.J.T.G., Bennett, W. A. & Miller, H. W. (1987) Enhancement of ovulation rate in gilts by increasing dietary energy and administering insulin during follicular growth. J. Anim. Sci. 64:507-516.

21. Bremer, J. (1963) Carnitine in intermediary metabolism—the biosynthesis of palmitoylcarnitine by cell subfractions. J. Biol. Chem. 238:2774-2779.[Free Full Text]

22. Coffey, T. M., Shireman, R. B., Herman, D. L. & Jons, E. E. (1991) Carnitine status and lipid utilization in neonatal piglets fed diets low in carnitine. J. Nutr. 121:1047-1053.

23. Baltzell, J. K., Bazer, F. W., Miguel, S. G. & Borum, P. R. (1987) The neonatal piglet as a model for human neonatal carnitine metabolism. J. Nutr. 117:754-757.

24. Owen, K. Q., Nelssen, J. L., Goodband, R. D., Weeden, T. L. & Blum, S. A. (1996) Effect of L-carnitine and soybean oil on growth performance and body composition of early-weaned pigs. J. Anim. Sci. 74:1612-1619.[Abstract]

25. Heo, K., Odle, J., Han, I. K., Cho, W., Seo, S., Van Heugten, E. & Pilkington, D. H. (2000) Dietary L-carnitine improves nitrogen utilization in growing pigs fed low energy, fat-containing diets. J. Nutr. 130:1809-1814.[Abstract/Free Full Text]

26. Owen, K. Q., Ji, H., Maxwell, C. V., Nelssen, J. L., Goodband, R. D., Tokach, M. D., Tremblay, G. C. & Koo, I. S. (2001) Dietary L-carnitine suppresses mitochondrial branched-chain keto acid dehydrogenase activity and enhances protein accretion and carcass characteristics of swine. J. Anim. Sci. 79:3104-3112.[Abstract/Free Full Text]

27. Owen, K. Q., Nelssen, J. L., Goodband, R. D., Tokach, M. D. & Friesen, K. G. (2001) Effect of dietary L-carnitine on growth performance and body composition in nursery and growing-finishing pigs. J. Anim. Sci. 79:1509-1515.[Abstract/Free Full Text]

28. Campbell, R. G. & Dunkin, A. C (1982) The effect of birth weight on the estimated milk intake, growth and body composition of sow-reared piglets. Anim. Prod. 35:185-192.

This article has been cited by other articles:

				K. R. Brown, R. D. Goodband, M. D. Tokach, S. S. Dritz, J. L. Nelssen, J. E. Minton, J. J. Higgins, J. C. Woodworth, and B. J. Johnson Growth characteristics, blood metabolites, and insulin-like growth factor system components in maternal tissues of gilts fed L-carnitine through day seventy of gestation J Anim Sci, July 1, 2007; 85(7): 1687 - 1694. [Abstract] [Full Text] [PDF]

				D. B. Carlson, J. C. Woodworth, and J. K. Drackley Effect of L-Carnitine Infusion and Feed Restriction on Carnitine Status in Lactating Holstein Cows J Dairy Sci, May 1, 2007; 90(5): 2367 - 2376. [Abstract] [Full Text] [PDF]

				C. Rehfeldt and G. Kuhn Consequences of birth weight for postnatal growth performance and carcass quality in pigs as related to myogenesis J Anim Sci, April 1, 2006; 84(13_suppl): E113 - E. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ramanau, A. Articles by Eder, K. Search for Related Content PubMed PubMed Citation Articles by Ramanau, A. Articles by Eder, K.