Publikationsdatenbank

Effects of essential fatty acids and conjugated linoleic acid on performance and energy metabolism in dairy cows from late gestation to early lactation (2021)

Art

Hochschulschrift

Autor

Vogel, Laura (WE 4)

Quelle

Gießen: DVG Service GmbH, 2021 — XXII, 178 Seiten

ISBN: 978-3-86345-606-1

Sprache

Englisch

Verweise

URL (Volltext): https://refubium.fu-berlin.de/handle/fub188/32590

Kontakt

Institut für Tierernährung

Königin-Luise-Str. 49
14195 Berlin
+49 30 838 52256
tierernaehrung@vetmed.fu-berlin.de

Abstract / Zusammenfassung

Common dairy cow nutrition changed from pasture-based feeding to barn systems with the incorporation of preserved feed with corn silage as the main component in the diet. Cows on pasture take up high amounts of essential fatty acids, especially α-linolenic acid. Corn silage, on the other hand, is rich in linoleic acid but contains low levels of fat and α-linolenic acid. The unsaturated α-linolenic and linoleic acid are classified as essential fatty acids because of the inability of mammals, including ruminants, to synthesize them endogenously de novo and must be obtained by feed, particularly in the form of fresh grass. Conjugated linoleic acid is a bioactive compound formed either in the rumen, by biohydrogenation from essential fatty acids, or is synthesized in mammary gland tissue. Therefore, feeding regime and forage type strongly affect the essential fatty acid status and n-6/n-3 fatty acid ratio as well as the conjugated linoleic acid status of dairy cows. The essential fatty acid and conjugated linoleic acid isomers might have distinct metabolic modulating characteristics and functions in dairy cows and conjugated linoleic acid effects can be partly independent of or synergistic to the effects of essential fatty acids. An insufficient essential fatty acid and conjugated linoleic acid supply might lead to impaired metabolic functions and additional supplementation with these fatty acids could potentially be useful in stabilizing the metabolism of a dairy cow, independently or in combination with each other, by compensating for an insufficient energy intake during the transition period, which could be utilized as a strategy to promote animal health and welfare. Therefore, a study with high-yielding dairy cows was conducted that aimed to assess the scope of impact of a combined essential fatty acid and conjugated linoleic acid supplementation on performance and energy utilization during the transition period and to inspect changes in milk composition with a reflecting milk fatty acid pattern resulting from pasture-based dairy nutrition. In the present study, the impact on lipid and glucose metabolism and the regulation of nutrient partitioning through the somatotropic axis resulting from the abomasal infusion of essential fatty acids, mainly α-linolenic acid, together with conjugated linoleic acid during late and early lactation was evaluated. High-yielding rumen cannulated German Holstein cows in their second lactation (n = 40) were set up in 5 blocks of 8 cows from wk 9 antepartum to wk 9 PP respectively, and dried off wk 6 before calving. The cows were fed with a corn-silage-based total mixed ration ad libitum to provide low amounts of essential fatty acids, especially α-linolenic acid, and conjugated linoleic acid. Cows were assigned to one of 4 treatment groups and abomasally supplemented with either coconut oil, linseed and safflower oil, conjugated linoleic acid, or a combination of the last two. Milk composition was then analyzed weekly, and blood samples were taken several times before and after parturition to determine plasma concentrations of metabolites and hormones related to lipid and glucose metabolism and somatotropic axis. Liver samples were obtained by biopsy on d 63 and 21 antepartum and on d 1, 28, and 63 postpartum to measure triglyceride and glycogen concentration and mRNA abundance of genes related to gluconeogenesis and the somatotropic axis. On d 28 antepartum and 21 postpartum, endogenous glucose production and glucose oxidation were measured via tracer technique. Body composition was determined after slaughter. Supplementation with conjugated linoleic acid was found to improve the energy status thanks to reduced milk fat concentration, increased body fat mass, and improved energy balance in late and early lactation. Furthermore, after calving, conjugated linoleic acid additives reduced non-esterified fatty acid concentration in plasma, lowered triglyceride and raised glycogen content in the liver, decreased endogenous glucose production, and stimulated the somatotropic axis. Thus, the critical metabolic situation of the negative energy balance after calving was shown to be alleviated by supplementation of conjugated linoleic acid. The different degrees of effects during late and early lactation were most likely not only a consequence of a different lactation stage but also due to the fact that cows in early lactation received the treatments for a much longer time. The essential fatty acid administration minorly interferes with the performance and lipid or glucose metabolism of transitioned cows. Treatment with exclusively essential fatty acids had hardly any influence on the endocrine regulation of nutrient partitioning during the investigated experimental period but resulted in the highest endogenous glucose production postpartum to retain glucose homeostasis, which might improve as well as stabilize a cow's overall metabolism. Our results indicate that supplementing essential fatty acid in ad-dition to conjugated linoleic acid may have influenced changes in mammary gland fatty metabolism achieved by conjugated linoleic acid and had a variable influence on hepatic mRNA expression. The combined treatment showed particularly similar results as the conjugated linoleic acid treatment and improved both the energy status of dairy cows (due to conjugated linoleic acid supplementation) and supposedly optimized cows’ periparturient metabolism (due to changes in hepatic glucose metabolism due to essential fatty acid supplementation). In summary, outcomes and possible impacts based on the findings were connected to a significant influence on performance and energy metabolism during late gestation and early lactation by supply of conjugated linoleic but not of α-linolenic acid or provision of a modified n-6/n-3 ratio. Metabolic and endocrine changes in blood plasma support the improved energy status in cows supplemented with conjugated linoleic acid, but additive essential fatty acid treatment, as in pasture feeding, does not improve the results. This study demonstrated that a fatty acid profile high in conjugated linoleic acid instead of α-linolenic is more crucial to ensure transition cow metabolic health during high production response in early lactation.