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Abstracts

Monday | Tuesday | Wednesday

Effects of Milk Consumption on Prenatal Growth and Twinning
Consumption of Cow's Milk and Measures of Foetal Growth: A Study Within the Danish National Birth Cohort
Sjurdur Olsen, PhD

Association of Low Intake of Milk and Vitamin D During Preganncy With Decreased Birth Weight
Kristine Koski, PhD, RD
Some pregnant women may be advised or choose to restrict milk comsumption and may not take appropriate supplements. We hypothesized that maternal milk restriction during pregnancy, which can reduce intakes of protein, calcium, riboflavin and vitamin D, might represent a health risk by lowering infant birth weight. When we controlled for previously established predictors of birth weight, our results showed that our healthy Canadian women consuming < 250mL/d of milk gave birth to infants who weighed less (3410 g vs 3530 g). The only nutrient to predict this lowered birth weight was intake of Vitamin D during pregnancy.

Bovine Hormones and Spontaneous Twinning in Humans
Gary Steinman, MD, PhD
The consumption or avoidance of milk correlates with the rate of twinning in humans. Insulin-like growth factor appears to be the active agent because of its ability to survive pasteurization and digestion as well as it known effect in stimulating ovulation. The rise in the national twinning rates parallels the use or prohibition of bST in cows.

Novel Regulatory Mechanisms of Fetal and Placental Growth by the Insulin-Like Growth Factor (IGF) System
Victor Han, MD, FRCP
Objectives: To determine the role of the IGF system in fetal and placental growth in normal and FGR, we have utilized environmental manipulation (maternal undernutrition) and genetic manipulation (transgenic and conditional gene targeting) to create a model of FGR in the mouse.
Results: Both undernutrition and overexpression of circulating IGFBP-1 caused significant growth restriction with different effects on the placenta, and phenotype-specific alterations in the IGF system genes. IGFBP-6 was identified as the major IGFBPs that was overexpressed in muscle of FGR mice. Cell biological studies demonstrated that IGFBP-6 inhibited growth and promoted apoptosis in both IGF-dependent and –independent actions.
Conclusions: Our data suggest that the circulating and tissue IGF system play differential roles in the regulation of fetal and placental growth, and IGFBP-1 and IGFBP-6 play IGF-dependent and –independent actions in tissue-specific manner.


Traditional Versus Current Milk Production Methods
Commercial Dairy Farming Practices – Then and Now
Xin Zhao, PhD
The dairy industry is one of the oldest established industries in North America. During the past 100 years, the dairy industry has experienced a broad array of major changes. In particular, the U. S. dairy industry has seen a nearly 6-fold increase in the average yield per cow over the span of the past 100 years. These major changes and underlining factors for these changes will be discussed in this talk. Establishment of the Dairy Herd Improvement Program, introduction of artificial insemination technology and application of sophisticated statistical models have contributed to significant genetic improvement in dairy cows. Better nutrition and better management practices are also responsible for increased milk yield per cow. Several modern methods to increase milk production will also be presented.

Milk Fatty Acid Composition: Lessons From the Human and from Mice
Margaret Neville, PhD

The fatty acids in milk are secreted in milk fat globules, mostly in the form of triacylglycerols. Although they provide a large proportion of the energy in milk, fatty acids, particularly the long-chain polyunsaturated forms, LC-PUFA, are also important for membrane formation. In human infants, for example, these fatty acids are transferred across the placenta and are used by the fetus for myelination of neurons in the last trimester of pregnancy. Because the enzymes for elongation and desaturation of fatty acids do not mature until sometime after birth, the high LC-PUFA of human milk may be important for membrane formation and myelination in the neonate as well. Mouse milk also contains significant quantities of LC-PUFA, likely synthesized within the mammary gland itself. In both humans and mice, these fatty acids can also be acquired from the diet, or from the adipose tissue of the animal. On the other hand, the content of LC-PUFA in cow's milk is low because of the saturation of fatty acids in the rumen. Fatty acids are also synthesized within mammary epithelium utilizing glucose or acetate as a substrate. The mechanisms of dietary regulation of the fatty acid composition of milk will be discussed along with the possibility that amino acids may, under some conditions, also serve as substrate for lipid synthesis.

Genetic Change in Dairy Cattle Over the Past Three Decades
Gary W Rogers, PhD

The efficient use of selective breeding has lead to dramatic increases in milk, butterfat, and protein yield in dairy cattle over the past several decades. However, the substantial genetic improvement in yield has had several important consequences, which are currently being addressed in breeding programs. Intense selection for milk yield has resulted in dairy cattle with reduced reproductive performance and with increased susceptibility to many diseases. Changes in milk constituents such as fatty acid profiles and hormone levels are not well documented, but some changes have likely occurred. Voluntary feed intake, nutrient partitioning and other metabolic processes have changed as a result of selection for increased yield. However, changes in feeding and management may have had a much larger impact on milk constituents than genetic change.

Reproductive and Endocrine Status/Function of the High Producing Lactating Dairy Cow:
“Foster Mother of the Human Race”
William Thatcher, PhD

Presentation will describe the current infertility of the high producing dairy cow due to hypo-secretion of reproductive hormones (i.e., estradiol and progesterone) in association with lactation. Systems to control ovulation to optimize fertility with physiological treatments of GnRH, PGF2α and progesterone will be described. Hypo-secretion of IGF-1 appears to be associated with low fertility, and pregnancy rates can be stimulated when dairy cows receive supplementation with bovine Somatotropin. Evidence will be presented that nutraceuticals, such as polyunsaturated fatty acids, can improve postpartum health and subsequent pregnancy rates via dietary supplementation.

Designer Milk by Embryo Biotechnologies
X Cindy Tian, PhD

Milk Hormones: Origin, Concentration, and Bioactivity
Craig Baumrucker, PhD

An extensive list of hormones detected in milk has been described. The origin of these factors, their mechanism of milk appearance, and selected hormone potential bioactivity will be addressed.

Measuring Hormones in Milk
Saskia Sterk, PhD
Hormone analysis in milk can range from quick and easy to time consuming
and very difficult using sophisticated techniques. This depends on the
information you want to obtan from the analysis. During the talk insight
will be given into the possibilities of instrumental analysis and generic
effect assays. Things to consider when planning the analyses and the effect
they can have on the results will also be discussed. The possibilities of analyzing growth hormone in milk, the current state of the art, will be briefly reviewed.


Hormone and IGF Levels in Different Types of Commercially Available Milk
Lindsay Frazier, MD, ScM

Removal of Caseins from the Milk of Transgenic Animals Using CaP Micro-Particles and “CaP-Insulin-Casein” Oral Insulin Delivery System
Tulin Morcol, PhD

This presentation will focus on a novel process for selective removal of caseins from regular milk or from milk of transgenic animals producing clinically important human therapeutics. Based on preliminary data and observations, we speculated that, being relatively large molecules and often containing Ca++-binding moieties, recombinant human proteins expressed in milk might be expressed with or entrapped within the 3D-network of casein micelles. Thus, during the early fractionation steps, these trapped proteins need to be freed from casein micelles for accurate detection and for purification. In our process, we first manipulated the casein micelles in milk with chelating agents and then removed them away from soluble proteins using our proprietary calcium phosphate (CaP) microparticles. As a result, the recombinant product was recovered in a casein-free clarified medium for further processing. In the second part of the presentation, a CaP-based oral insulin delivery system containing casein as the protective outer layer will be described.

Milk Effects in Animal Models
Activation of Aryl Hydrocarbon Receptor (AhR) by Infant Formula and Human Milk
Shinya Ito, MD, ABCP, FRCPC
Compared to infant formula, human milk is known to contain high levels of
persistent organic pollutants, which may pose health risks through the
Ah-receptor mediated pathway. However, does human milk really activate AhR?


Studies Regarding Intestinal Absorption and Action of Insulin-Like Growth Factors in the Newborn
Anthony Philipps, MD

Insulin-Like Growth Factors I and II (IGF's), although synthesized endogenously, are also present in mammalian milks and probably play a role in intestinal growth and development in early postnatal life. In addition, there is some evidence that they, particularly IGF-I, are absorbed biologically intact into the portal circulation and perhaps systemic as well. Mechanisms of action and absorption will also be discussed as well as speculation on the roles of these potent growth factors in the neonate.

Health Effects of Cow’s Milk
Akio Sato, MD
Ganmaa Davaasambuu, PhD

Birth Weight and Risk of Mammary Cancer
Leena Hilakivi-Clarke, PhD
The observation that high birth weight is associated with increased breast cancer risk suggests that hormone and growth factor levels during normal pregnancy affect later risk of developing this disease. In our animal study, high birth weight increased mammary cancer in rats and was linked to elevated fetal leptin levels. The high birth weight rats also exhibited reduced expression of estrogen receptor a and increased activation of mitogen activated protein kinase (MAPK) in their mammary glands. In addition, mammary epithelial cell proliferation was increased and the glands contained more terminal end buds – structures that are the sites of malignant transformation. These findings indicate that fetal factors leading to altered birth weight induce epigenetic modifications in the mammary gland and consequently alter the developmental programming of genes that regulate mammary gland development and susceptibility to breast cancer.


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