Nutrient requirements of dairy cattle , Nutrient requirements of dairy cattle , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Nutrient requirements of dairy cattle

1 Many human fetuses have to adapt to a limited supply of nutrients In doing so they permanently change their structure and metabolism 2 These 'programmed' changes may be the origins of a number of diseases in later life, including coronary heart disease and the related disorders stroke, diabetes and hypertension 3 This review examines the evidence linking these diseases to fetal undernutrition and provides an overview of previous studies in this area

In utero programming of chronic disease

https://www.webpages.uidaho.edu/ruminant_nutrition/Reading%20materials%20411/dietary%20factors%20affecting%20feed%20intake-Allen2000.pdf

Effects of Diet on Short-Term Regulation of Feed Intake by Lactating Dairy Cattle

Roles of growth hormone and insulin-like growth factor 1 in mouse postnatal growth.

Effect of Feed on the Composition of Milk Fat

Changes in mammary gland histology, dry weights, nucleic acids and in vitro rates of substrate oxidation in incorporation into lipid were measured in mammary biopsies of three gilts each on d 30, 45, 60, 75, 90, 105 and 112 of pregnancy, and d 1 and 4 of lactation. Histological changes noted were progressive duct growth early in pregnancy followed by rapid lobulo-alveolar development between d 75 and 90 to complete mammogenesis. Colostrum and lipid were evident by d 105 with marked distension of alveolar lumina on d 112. Complete differentiation of the secretory process was apparent on the day of parturition. Concentrtion of dry, fat-free tissue (DFFT) and DNA changed little before d 60 but increased fourfold between d 75 and 90. No further increases in DFFT or DNA were noted. RNA concentrations paralleled DNA through d 90, after which they steadily increased. Rates of acetate and glucose oxidation increased transiently during midpregnancy then declined and remained low until initiation of lactogenesis. Substrate incorporation into lipid increased slightly at midpregnancy and again at d 105, after which it increased markedly. Collectively, results indicate that mammogenesis is complete by d 90, after which lactogenesis is initiated in a two-stage process. Metabolic rates expressed on a DNA basis indicated considerable rates of oxidation, but not of lipogenesis by proliferating mammary tissue. Preferential metabolism of acetate vs glucose near parturition suggests coordination of metabolism between the mammary gland and other maternal tissues.

Nucleic acid, metabolic and histological changes in gilt mammary tissue during pregnancy and lactogenesis.

The effects of accelerated growth rates and estrogen implants in prepubertal Holstein heifers on estimates of mammary development and subsequent reproduction and milk production

Nutrient Uptake and Endocrine Regulation of Milk Synthesis by Mammary Tissue of Lactating Sows

Evidence is discussed which indicates that nutrient partitioning between muscle and adipose tissue can be altered by growth hormone administration in meat animals. In the limited number of studies conducted with meat animals, growth rate, feed efficiency and carcass composition were improved by growth hormone administration. When insulin was administered to normally growing swine no improvement in growth performance was observed. The mechanisms by which growth hormone affects growth performance are not clear but considerable data from rodent studies exist to indicate that many of the growth promoting effects of this hormone are due to somatomedins. However, few data are available for meat animals to indicate whether the growth promoting effects of growth hormone are mediated by somatomedins. Knowledge about the mechanisms that regulate growth hormone synthesis, secretion and biological action is accumulating. It is apparent that growth hormone administration induces an insulin-resistant state in rodents and meat animals. It is not clear whether chronic growth hormone administration in meat animals induces a growth hormone resistant state. Based on the available information, manipulation of systemic hormone concentrations and(or) tissue sensitivity to hormones involved in growth and differentiation may result in means to manipulate fetal and postnatal growth and development.

R.S. Kensinger

Papers

Nucleic acid, metabolic and histological changes in gilt mammary tissue during pregnancy and lactogenesis.

The effects of accelerated growth rates and estrogen implants in prepubertal Holstein heifers on estimates of mammary development and subsequent reproduction and milk production

Nutrient Uptake and Endocrine Regulation of Milk Synthesis by Mammary Tissue of Lactating Sows

Endocrine regulation of fetal and postnatal meat animal growth.

Estrone and 17β-estradiol concentrations in pasteurized-homogenized milk and commercial dairy products