Tag: Ruminant digestion

Carbohydrates typically comprise 60 to 70 percent of diets for animals like dairy cattle, making them the most significant source of dietary energy. This macronutrient class is not only crucial for powering daily activities but also plays a fundamental role in maintaining gastrointestinal health and metabolic processes.

Approximately 60-70% of a typical dairy cow's diet is comprised of carbohydrates. Basal energy feed, often referred to as a carbohydrate concentrate, is a high-energy animal feed that provides the necessary sugars and starches to power the vital functions of livestock and other animals. These feeds are low in crude fiber, low in protein, and are highly digestible to provide an efficient source of calories.

In principle, a human could physically eat grass, but a study published in the Proceedings of the National Academy of Sciences confirms that we cannot effectively digest it. Our digestive systems lack the necessary enzymes and structure to process the cellulose, meaning that while you might fill your stomach, you would ultimately starve. This biological limitation reveals a fundamental difference between humans and grazing animals.

Over 50% of the world's mammals are herbivores, yet plants are generally considered poor sources of protein. So, how did herbivores get protein to build their massive muscles and robust bodies? The answer lies not just in the plants they eat, but in the complex, symbiotic relationships with microbes that have evolved within their digestive systems.

Approximately 73% of cellulose consumed by humans passes through the digestive system undigested, primarily acting as dietary fiber. The answer to 'Can cellulose be used as a source of energy for humans?' is, for the most part, no, due to a key enzymatic deficiency in our digestive system.

The average person consumes approximately 15 grams of fiber, including cellulose, per day, yet it passes through our system largely untouched. We can easily digest starch, another plant carbohydrate, but why can't human beings digest cellulose, the most abundant organic polymer on Earth?. The answer is rooted in our evolutionary history and the specific enzymes our bodies produce.

Unlike almost all other vitamins, Vitamin B12 is not synthesized by plants, animals, or fungi, but exclusively by certain species of bacteria and archaea. This unique biological process means that humans and other animals must obtain this crucial nutrient from external sources, primarily through their diet. This fact forms the basis for understanding all dietary sources of Vitamin B12, from animal products to fortified foods and supplements.

In 2018, a study published in the Journal of Dairy Science detailed the numerous microbial, chemical, and plant toxin hazards present in silage, highlighting why it is unsuitable and potentially dangerous for humans to eat. Silage is a fermented forage crop, but while it is a nutritional staple for livestock, the human digestive system is neither designed to process it nor equipped to handle the associated health risks.

Cellulose is the most abundant organic polymer on Earth, forming the rigid structural component of all plant cell walls. However, despite its ubiquity in our plant-based foods, the simple answer to why is cellulose not fit for human diet is that humans lack the specific enzymes required to break it down. While indigestible, this complex carbohydrate plays a crucial role in maintaining digestive health.

It takes approximately 80 hours for fibrous grass to pass through a bison's digestive tract, allowing for maximum nutrient absorption from lower-quality forage. This prolonged digestive period is a key survival adaptation that distinguishes bison from many other herbivores.