Effects of a Maternal Essential Fatty Acid and Conjugated Linoleic Acid Supplementation during Late Pregnancy and Early Lactation on Hematologic and Immunological Traits and the Oxidative and Anti-Oxidative Status in Blood Plasma of Neonatal Calves.

Fatty acids are known for their regulatory role in inflammation and oxidative stress. The present study investigated 38 calves born from dams, abomasally supplemented with coconut oil, essential fatty acids (EFA), conjugated linoleic acid (CLA) or EFA + CLA, according to immunological traits and the oxidative and anti-oxidative status for the first 5 days of life. On day 2 of life, plasma total bilirubin, cholesterol, interleukin 1-ß and ferric ion reducing anti-oxygen power (FRAP) were lower in calves with than without maternal EFA supplementation, and FRAP additionally on day 4. On day 3, the concentrations of reactive oxygen metabolites were higher in calves with than without maternal EFA supplementation and additionally on day 5 together of retinol. Total leucocyte counts were decreased in the EFA group compared to the CLA group on day 5. Lymphocyte proportions decreased from day 1 to 5 only in the EFA + CLA group. On day 2, plasma total protein was higher in CLA and EFA + CLA than in EFA calves. Similarly, CLA calves had higher interleukin 1-ß concentrations compared to EFA + CLA calves. FRAP was decreased by CLA on day 4. Overall, the maternal fatty acid supply affected the inflammatory response and the oxidative and anti-oxidative status of the neonatal offspring.

Effects of Feeding Milk Replacer Ad Libitum or in Restricted Amounts for the First Five Weeks of Life on the Growth, Metabolic Adaptation, and Immune Status of Newborn Calves.

The pre-weaning period is critical for calf health and growth, and intensive milk feeding programs may assist postnatal development by improving body growth and organ maturation. The aim of the present work was to study the effects of ad libitum milk replacer (MR) feeding on the growth, metabolic adaptation, health, and immune status of newborn calves. Twenty-eight newborn Holstein and Holstein x Charolais crossbred calves were fed ad libitum (ADLIB) or in restricted amounts (6 liters per day; RES) during the first five weeks of life. The MR intake in the ADLIB treatment was gradually reduced at weeks 6 and 7, and all calves then received 6 liters of MR per day until day 60. Blood samples were collected to measure the plasma concentrations of metabolites, insulin, insulin-like growth factor (IGF)-I and IGF binding proteins (IGFBP), immunoglobulins, and acute phase proteins. The expression of mRNA associated with both the somatotropic axis and gluconeogenic enzymes was measured in the liver on day 60. Intensive feeding improved MR intake and growth in ADLIB without influencing concentrate intake. Carcass weight, perirenal fat, and muscle mass were greater in ADLIB. Plasma concentrations of glucose, triglycerides, insulin, and IGF-I were greater, whereas plasma concentrations of ß-hydroxybutyrate, total protein, albumin, urea, IGFBP-2 and -4, and fibrinogen were lower at distinct time points in ADLIB. The hepatic mRNA expression of cytosolic phosphoenolpyruvate carboxykinase was greater in ADLIB. Most metabolic and endocrine differences occurred during the MR feeding period, but a slightly greater concentrate intake was associated with increased plasma IGF-I and insulin at the end of the study. The immune and health status of the calves were not affected by MR feeding. However, increased plasma fibrinogen in the RES group suggested differences in the acute phase response.

Reduced AgRP activation in the hypothalamus of cows with high extent of fat mobilization after parturition.

Agouti-related protein (AgRP), produced by neurons located in the arcuate nucleus of the hypothalamus stimulates feed intake. During early lactation dairy cows increase their feed intake and additionally mobilize their fat reserves leading to increased plasma non-esterified fatty acid (NEFA) concentrations. Since cows with a higher extent of fat mobilization exhibit the lower feed intake, it seems that high NEFA concentrations confine hyperphagia. To test the involvement of AgRP neurons, we investigated 18 cows from parturition until day 40 postpartum (pp) and assigned the cows according to their NEFA concentration on day 40pp to either group H (high NEFA) or L (low NEFA). Both groups had comparable feed intake, body weight, milk yield, energy balance, plasma amino acids and leptin concentrations. Studies in respiratory chambers revealed the higher oxygen consumption and the lower respiratory quotient (RQ) in H compared to L cows. mRNA abundance of neuropeptide Y, peroxisome proliferator-activated receptor-gamma, AMP-activated protein kinase, and leptin receptor in the arcuate nucleus were comparable between groups. Immunohistochemical studies revealed the same number of AgRP neurons in H and L cows. AgRP neurons were co-localized with phosphorylated adenosine monophosphate-activated kinase without any differences between groups. The percentage of cFOS-activated AgRP neurons per total AgRP cells was lower in H cows and correlated negatively with oxygen consumption and NEFA, positively with RQ, but not with feed intake. We conclude that AgRP activation plays a pivotal role in the regulation of substrate utilization and metabolic rate in high NEFA dairy cows during early lactation.

Plasma ghrelin is positively associated with body fat, liver fat and milk fat content but not with feed intake of dairy cows after parturition.

Ghrelin is a gastrointestinal peptide hormone that is present in blood mostly in a non-posttranslationally modified form, with a minor proportion acylated at Ser(3). Both ghrelin forms were initially assigned a role in the control of food intake but there is accumulating evidence for their involvement in fat allocation and utilization. We investigated changes in the ghrelin system in dairy cows, exhibiting differences in body fat mobilization and fatty liver, from late pregnancy to early lactation. Sixteen dairy cows underwent liver biopsy and were retrospectively grouped based on high (H) or low (L) liver fat content post-partum. Both groups had a comparable feed intake in week -6 (before parturition) and week 2 (after parturition). Only before parturition was preprandial total ghrelin concentration higher in L than in H cows and only after parturition was the basal plasma concentration of non-esterified fatty acids higher in H than in L cows. Both before and after parturition, H cows had higher preprandial plasma concentrations of acyl ghrelin, a higher acyl:total ghrelin ratio, lower plasma triacylglyceride concentrations and a lower respiratory quotient compared with L cows. These group differences could not be attributed to an allelic variant of the acyl ghrelin receptor. Rather, the ratio of acyl:total ghrelin correlated with several aspects of fat metabolism and with respiratory quotient but not with feed intake. These results show that endogenous ghrelin forms are associated with fat allocation, fatty liver, and utilization of fat during the periparturient period.

Increased anaplerosis, TCA cycling, and oxidative phosphorylation in the liver of dairy cows with intensive body fat mobilization during early lactation.

The onset of milk production lets mammals experience an enormous energy and nutrient demand. To meet these requirements, high-yielding dairy cows mobilize body fat resulting in an augmented hepatic oxidative metabolism, which has been suggested to signal for depressing hunger after calving. To examine how the extent of fat mobilization influences hepatic oxidative metabolism and thus potentially feed intake, blood and liver samples of 19 Holstein cows were taken throughout the periparturient period. Retrospectively grouped according to high (H) and low (L) liver fat content, H cows showed higher fatty acid but lower amino acid plasma concentrations and lower feed intake than L cows. The hepatic phospho-AMPK/total AMP ratio was not different between groups but decreased after parturition. A 2-DE coupled MALDI-TOF-TOF analysis and qRT-PCR studies revealed H cows having lower expressions of major enzymes involved in mitochondrial ß-oxidation, urea cycling, and the pentose phosphate pathway but higher expressions of enzymes participating in peroxisomal and endoplasmic fatty acid degradation, pyruvate and TCA cycling, amino acid catabolism, oxidative phosphorylation, and oxidative stress defense. These data indicate that increasing lipolysis leads to augmenting nutrient catabolism for anaplerosis and mitochondrial respiration, providing a molecular link between hepatic oxidative processes and feed intake.