![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
-Linolenic Acid–Rich Milk during Suckling but Not When Fed -Linolenic Acid–Rich Diets after Weaning1–3,
,4
* Department of Small Animal Clinical Sciences, Comparative Nutrition Laboratory, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843 and ** Nestle-Purina Pet Care, St. Louis, MO
4 To whom correspondence should be addressed. E-mail: jbauer{at}cvm.tamu.edu.
KEY WORDS: • docosahexaenoic acid • canine puppies • milk • alpha-linolenic acid
Docosahexaenoic acid (DHA)5 is important for proper neurological development of humans and animals (1). In growing animals, 4 ways exist to meet the DHA requirement of neural tissues: uptake of DHA directly from dietary sources; desaturation and elongation of ALA within the neural tissues; uptake of intermediate ALA derivatives such as DPA after hepatic conversion with further synthesis in neurologic tissues to DHA; and uptake of circulating DHA synthesized in tissues such as liver. After parturition, maternal milk serves as the sole exogenous source of long-chain PUFA (LC-PUFA) for the newborn. Its fatty acid profile is reflected in the maternal dietary fat intake (2,3). Francois et al. (2) observed the effects of 6 dietary fats, including menhaden oil, on breast milk fatty acids for 6 d after a single fatty meal. In the menhaden oil group, DHA appeared within 6 h after the meal, peaked within 24 h, and remained elevated for up to 3 d. Francois et al. (4) also conducted a study in which lactating women were supplemented with 20 g flaxseed oil (10.7 g ALA) for 4 wk. Although some enrichment of milk eicosapentaenoic (EPA) and DPA was found, there was no accumulation of DHA. Although unexpected, this finding likely reflects the need for peroxisomal synthesis from DPA which may not occur in mammary tissue.
We have similarly observed that the milk of dogs fed flaxseed oil diets from gestation onward is enriched only in ALA and not EPA or DHA (5). The purpose of the present study was thus to determine whether the suckling of ALA-rich milk by puppies results in DHA synthesis. Such a finding would support the capacity of puppies to utilize 18 carbon (n-3) fatty acid precursors in milk to meet their DHA needs and provide an alternate source of this fatty acid for neurologic development and function.
 |
MATERIALS AND METHODS |
|---|
 TOP MATERIALS AND METHODS RESULTSDISCUSSIONLITERATURE CITED |
|---|
|
Weaning was initiated at 21 d of age, at which time a gruel consisting of the mothers' respective diets and water was offered to the puppies 3 times/d in addition to suckling. This technique gradually decreased the time the puppies spent suckling; they were completely weaned by d 42. After weaning, puppies consumed the same diets as their mothers until 12 wk of age. The puppies were weighed daily until 6 wk of age and twice weekly thereafter to monitor proper growth and development. One puppy that failed to thrive was removed from the study and supplemented to ensure proper nutrition.
Plasma and milk total lipids were extracted using chloroform:methanol (2:1, v:v); total plasma phospholipids (PL) were separated via TLC, and FAME were prepared with the plasma PL and milk total lipids as described previously (7). Fatty acid profiles were determined via capillary GC (7).
Statistical analyses were performed by repeated-measures ANOVA followed by Bonferroni multiple comparisons at P < 0.05 or as otherwise noted as appropriate.
|
RESULTS |
|---|
|
TOPMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
There were no time or time x diet effects observed for any fatty acid in either the milk or plasma samples. Thus, values reported are those obtained after combining all 4 sample days during suckling and both sample days during the postweaning period. Analysis of these data revealed main diet effects. Enrichment of ALA in canine milk from the High-ALA group vs. the Low-ALA group occurred at all sample times (P < 0.05), and EPA and DHA did not differ (Table 2). There was considerable variation in the amount of these 2 latter fatty acids. However, overall values were small and not unexpected given the fatty acid composition of diets fed to the dams. More importantly, puppies consuming this milk during suckling showed that plasma PL fatty acids were not only higher in ALA but also enriched in both EPA and DHA compared with control puppies (P < 0.05). After weaning, ALA and EPA remained higher than in control puppies, but DHA did not differ during this time (Fig. 1).
|
|
|
DISCUSSION |
|---|
|
TOPMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
By contrast, when adult dogs are fed increased amounts of ALA, no additional accumulation of plasma PL-DHA occurs (11,12). Yet, under similar dietary conditions, neonatal puppies appear to have considerable PL-DHA in their plasma. Although reasons for this observation are unknown, it appears that neonatal canines preferentially synthesize DHA at a time of life when demand for this fatty acid is especially high. This observation suggests that peroxisomal conversion of DPA to DHA by dogs during suckling may be more active than in adults.
It should be noted that the amounts of the major (n-6) and (n-3) fatty acids of puppy plasma-PL did not differ during suckling and after weaning within each diet with one notable exception. During suckling, plasma PL-DHA was higher in the High-ALA group puppies compared with the Low-ALA group; nevertheless, after weaning, this fatty acid did not differ between the diet groups. This suggests that the capacity of puppies to synthesize plasma PL-DHA from dietary ALA or other (n-3) fatty acid precursors appears to be active for only a short time during the neonatal period and is blunted thereafter. Thus, during this active period of development, ALA may be sufficient as a dietary precursor for the synthesis of requisite amounts of DHA. However, what minimal amount of dietary ALA supports this conversion or what amount may be needed to optimize it for neural or other developmental needs in companion animals is unknown. It may be that a LA:ALA ratio at the lower end of the recommended range (13) is preferred. Additionally, because both (n-6) and (n-3) fatty acids compete for the same enzyme systems, the extent to which relative amounts of linoleic acid may affect the conversion of DHA from the ALA precursor also remains to be determined.
|
ACKNOWLEDGMENTS |
|---|
|
FOOTNOTES |
|---|
2 Author disclosure: The corresponding author's lodging expenses at the symposium were paid by The WALTHAM Centre for Pet Nutrition.
3 Funded by Nestlé-Purina PetCare, St. Louis, MO and the Mark L. Morris Professorship in Clinical Nutrition, Texas A&M University.
5 Abbreviations used: AA, arachidonic acid; ALA, 
-linolenic acid; DHA, docosahexaenoic acid; DPA, docosapentaenoic acid; EPA, eicosapentaenoic acid; LC-PUFA, long-chain PUFA; PL, phospholipid; ROS, rod outer segment; RPE, retinal pigment epithelium.
|
LITERATURE CITED |
|---|
|
TOPMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
1. Clandinin MT, Chappell JE, Leong S, Heim T, Swyer PR, Chance GW. Intrauterine fatty acid accretion rates in human brain: implications for fatty acid requirements. Early Hum Dev. 1980;4:121–9.[Medline]
2. Francois CA, Connor SL, Wander RC, Connor WE. Acute effects of dietary fatty acids on the fatty acids of human milk. Am J Clin Nutr. 1988;67:301–8.
3. Helland IB, Saarem K, Saugstad OD, Drevon CA. Fatty acid composition in maternal milk and plasma during supplementation with cod liver oil. Eur J Clin Nutr. 1998;52:839–45.[Medline]
4. Francois CA, Connor SL, Bolewicz LC, Connor WE. Supplementing lactating women with flaxseed oil does not increase docosahexaenoic acid in their milk. Am J Clin Nutr. 2003;77:226–33.
5. Bauer JE, Heinemann KM, Bigley KE, Lees GE, Waldron MK. Maternal diet alpha-linolenic acid during gestation and lactation does not increase canine milk docosahexaenoic acid. J Nutr. 2004;134:2035S–8.
6. Heinemann KM, Waldron MK, Bigley KE, Lees GE, Bauer JE. Long-chain (n-3) polyunsaturated fatty acids are more efficient than -linolenic acid in improving electroretinogram responses of puppies exposed during gestation, lactation, and weaning. J Nutr. 2005;135:1960–6.
7. Bauer JE, McAlister KG, Rawlings JM, Markwell P. Molecular species of cholesteryl esters formed via plasma lecithin:cholesterol acyltransferase in fish oil supplemented dogs. Nutr Res. 1997;17:861–72.
8. Sauerwald TU, Hachey DL, Jensen CL, Chen H, Anderson RE, Heird WC. Intermediates in endogenous synthesis of C22:6 omega 3 and C20:4 omega 6 by term and preterm infants. Pediatr Res. 1997;41:183–7.[Medline]
9. Szitanyi P, Koletzko B, Mydlilova A, Demmelmair H. Metabolism of 13C-labeled linoleic acid in newborn infants during the first week of life. Pediatr Res. 1999;45:669–73.[Medline]
10. Rodriguez A, Sarda P, Nessmann C, Boulot P, Leger CL, Descomps B. 
6- and 5-Desaturase activity in human foetal liver: Kinetic Aspects. J Lipid Res. 1998;39:1825–32.
11. Bauer JE, Dunbar BL, Bigley KE. Dietary flaxseed in dogs results in differential transport and metabolism of n-3 polyunsaturated fatty acids. J Nutr. 1998;128: Suppl:2641S–4.
12. Bauer JE, Heinemann KM, Lees GE, Waldron MK. Retinal functions of young dogs are improved and maternal plasma phospholipids are altered with diets containing long-chain n-3 polyunsaturated fatty acids during gestation, lactation, and after weaning. J Nutr. 2006;136:1991S–94S.
13. National Research Council (NRC). Nutrient requirements of dogs and cats. Washington DC: National Academy Press. 2006.
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
