Lipid metabolism in the adipose tissue of ruminant animals

Publisher Summary
This chapter discusses lipid metabolism in the adipose tissue of ruminant animals. Adipose tissue has a critical role as an energy source during lactation in high milk-yielding cows, but it is also implicated in the depression in the yield of milk fat found in animals fed high-concentrate diets. The dominant factor that determines the direction of the metabolic flux of adipose tissue in all species is the energy balance of the animal. This is modulated by the composition of the diet that determines the relative contribution of exogenous fatty acids and fatty acid synthesis to lipid deposition during anabolic metabolism. However, there are also mechanisms that ensure that partition of nutrients between adipose tissue and other parts of the body normally favors the latter. Thus, skeletal and musculature development precedes fattening, and fetal growth and milk production usually take precedence over fat accumulation. Adipose tissue metabolism responds to variations in the availability of nutrients in the blood and the activity of the sympathetic nervous system. The role of the sympathetic nervous system in promoting lipolysis during certain conditions is clear, but the role under other conditions of increased lipolysis has not been defined.

The aim of the present work is to study whether the introduction of rosemary plant byproduct, from plant steam distillation, in daily Segurena sheep feeding allows the transfer of active antioxidant components to lamb meat, without detriment to the animal productivity. For this, 36 Segurena ewes were assigned randomly to three homogeneous groups. One group was fed a basal diet as a control and the diet of the other two groups was modified by substituting 10 or 20% of the control diet (respectively) with distilled rosemary leaves. Chromatographic analysis allowed the identification of 11 polyphenolic components previously identified in the rosemary and basal diet pellets, respectively. Among them, rosmarinic acid, carnosol, and carnosic acid were the phenolic components that had a significantly increased presence (P < 0.05) in the lamb meat from sheep mothers fed this aromatic herb, when compared to the control group. The incorporation of this byproduct into the animal diet favored the antioxidant capacity...

Polyphenolic Transmission to Segureño Lamb Meat from Ewesʼ Diet Supplemented with the Distillate from Rosemary (Rosmarinus officinalis) Leaves

The values shown in Table 1 are from sheep designated “fed”. Plasma glucose may range from 550 to 1100 mg/l — the higher values may be due to pre-sampling excitement among animals. The values in Table 1 were selected because fairly large numbers of animals were used (20) or measurements were made at intervals over two years (59).

Carbohydrate and Lipid Metabolism

Concentrations of plasma non-esterified fatty acids (NEFA) in sheep were found to be within the range 0.1–0.9 m-equiv/l. Relatively high levels (1.0–2.5 m-equiv/l) occurred in pregnant and non-pregnant sheep when fasted. Intravenous injection of glucose (1.0 g/kg body wt.) depressed KEFA concentrations to levels of about 0.05 m-equiv/l. Insulin, injected intravenously, caused an initial fall in the NEFA level, followed by a sharp rise which was maintained throughout hypoglycaemia. These results suggest that in sheep, as in many other species, NEBA are of major metabolic importance.

Plasma non-esterified fatty acids in sheep.

The objective of the investigations reported in this paper was to examine the possibility of using plasma free fatty acid concentrations as a means of estimating food requirements for maintenance purposes in sheep. Estimates derived in these investigations are considered to be less satisfactory than those based on live-weight change. It is concluded, however, that the technique merits further consideration, and that, with more precise knowledge of FFA concentrations in maintenance-fed sheep and of the FFA: food intake response curve, it could provide a useful alternative means of estimating maintenance requirements.

A. J. F. Russel

Papers

Observations on the use of plasma free fatty acid concentrations in the determination of maintenance requirements of sheep.