METABOLISME KARBOHIDRAT PADA TERNAK RUMINANSIA - Oleh Haridsyah

Summary

This lecture covers the process of carbohydrate metabolism in ruminants, highlighting the role of microbial fermentation in the rumen. It explains how ruminants digest complex carbohydrates like cellulose and hemicellulose, which are broken down by microorganisms into volatile fatty acids (VFAs) such as acetic acid, propionic acid, and butyric acid. These VFAs are absorbed and utilized for energy production, fat synthesis, and gluconeogenesis. The transcript also emphasizes the differences in carbohydrate metabolism between ruminants and monogastric animals, and the importance of the rumen's microbial community in digestion and overall metabolic health.

Takeaways

• 😀 Ruminant animals' diet consists of 60-70% carbohydrates, mainly in the form of cellulose, hemicellulose, and starch, which are fermented by rumen microbes.
• 😀 Unlike monogastric animals, ruminants rely on rumen microorganisms for carbohydrate digestion, producing volatile fatty acids (VFAs) such as acetate, propionate, and butyrate as the end products.
• 😀 Carbohydrates in ruminants are divided into soluble (sugars and starch) and insoluble (cellulose, hemicellulose) types, with different digestion pathways.
• 😀 Rumen microbes, including bacteria, fungi, and protozoa, break down fibrous carbohydrates like cellulose into simpler sugars and oligosaccharides, which are further fermented into VFAs.
• 😀 The fermentation process in the rumen produces not only VFAs but also gases such as methane (CH4), carbon dioxide (CO2), and hydrogen (H2), which are expelled through belching (eructation).
• 😀 VFAs like acetate, propionate, and butyrate are absorbed by the rumen wall, enter the bloodstream, and are utilized by body tissues for energy and biosynthesis.
• 😀 Acetate and butyrate contribute to the synthesis of milk fat in ruminants, while propionate plays a key role in glucose synthesis through gluconeogenesis.
• 😀 Microbial enzymes in the rumen (not enzymes from the ruminant itself) are responsible for the fermentation and breakdown of carbohydrates into VFAs.
• 😀 The composition of VFAs in the rumen is dominated by acetate, propionate, and butyrate, with smaller amounts of other acids like formate, isobutyrate, and valerate.
• 😀 The metabolic pathways of acetate, propionate, and butyrate include their conversion into various compounds such as acetyl-CoA (for energy metabolism), oxaloacetate (for glucose synthesis), and beta-hydroxybutyrate (for ketone formation).

Q & A

What are the primary carbohydrates in ruminant feed according to Tielman et al.?

According to Tielman et al., 60-70% of ruminant feed consists of carbohydrates, mainly cellulose, hemicellulose, and starch.

How do the carbohydrate metabolism processes differ between ruminants and monogastric animals?

In monogastric animals, carbohydrate metabolism is primarily influenced by enzymes, leading to glucose production. In ruminants, carbohydrate metabolism is influenced by rumen microorganisms, resulting in the production of volatile fatty acids (VFAs) instead.

What are the two types of carbohydrates mentioned in the script, and how do they differ?

The two types of carbohydrates mentioned are 'soluble carbohydrates' (such as sugars and starch) and 'insoluble carbohydrates' (such as cellulose and hemicellulose). Soluble carbohydrates are easier to digest, while insoluble carbohydrates are fermented by rumen microbes.

What are volatile fatty acids (VFAs), and which ones are most commonly found in ruminant rumen?

Volatile fatty acids (VFAs) are the end products of carbohydrate fermentation in the rumen. The most common VFAs in ruminants are acetic acid, propionic acid, and butyric acid.

How are carbohydrates broken down into VFAs in the rumen?

The breakdown of carbohydrates into VFAs in the rumen occurs in two stages: first, extracellular hydrolysis of complex carbohydrates like cellulose and hemicellulose into simple sugars; second, the fermentation of these sugars by rumen microbes into VFAs.

What gases are produced during carbohydrate metabolism in ruminants?

During carbohydrate metabolism in ruminants, gases such as methane (CH4), carbon dioxide (CO2), and hydrogen (H2) are produced, which are expelled through eructation (belching).

What happens to VFAs after they are absorbed through the rumen wall?

After VFAs are absorbed through the rumen wall, they enter the bloodstream and are transported to body tissues, where they undergo further metabolic processes, such as biosynthesis of fats and glucose.

What role does acetic acid play in ruminant metabolism?

Acetic acid is mainly used for biosynthesis of milk fats in ruminants. It is metabolized into acetyl-CoA, which is then utilized in the citric acid cycle for energy production and fat synthesis.

How is propionic acid utilized in ruminant metabolism?

Propionic acid is converted into glucose through gluconeogenesis in the liver, which is essential for energy metabolism in ruminants.

What is the role of butyric acid in ruminant metabolism?

Butyric acid is mainly metabolized into ketones, particularly beta-hydroxybutyrate, which serves as an energy source and is used in the liver and other tissues.