WINTER BONUS MAGAZINE 2025

forestomach compartments in ruminants change significantly with age. At birth, the rumen and reticulum are small, nonfunctional, and account for only 39% of the total stomach volume. These compartments lack microorganisms, and the rumen papillae and the omasum folds are still undeveloped. In this phase of life, the calf’s largest stomach compartment is the abomasum, constituting more than 50% of the total stomach area. The rumen wall is very thin with limited muscularisation and blood supply, and there are also minimal to no rumen papillae present. The rumen and reticulum will remain undeveloped and nonfunctional as long as the diet is restricted to milk. There is a structure called the oesophageal groove located in the reticulum wall that allows milk to bypass the rumen and directly enter the omasum and abomasum. The calf’s nursing behaviour causes a reflex action that closes the oesophageal groove, which prevents milk from entering the rumen. The size of the rumen (the volume) drastically increases from birth with a massive growth spurt significantly faster than the rest of the body. In the first weeks after birth the animal will get sufficient nutrition from the milk, but as the milk volume and density starts to decrease, the young animal must get more and more absorbable nutrients from the rumen to make up for the shortage of milk. n Development ruminant is born, it is born with an underdeveloped rumen and reticulum. The neonate is essentially a mono ning its gastrointestinal system. Th relativ size and development of the forestomach compartments in ru significantly with ge. At birth, the rumen and reticulum are small, nonfunctional, and account for only 39% of t h volume. These compartments lack microorganisms, and the rumen papillae and the omasum folds loped. In this phase of life, the calf’s largest stomach compartment is the abomasum, constituting more than l stomach area. The rumen wall is very thin with limited muscularization and blood supply, and there are also men papillae present. en and reticulum will remain undeveloped and nonfunctional as long as the diet is restricted to milk. There is a st he oesophageal groove located in the reticulum wall that allows milk to bypass the rumen and directly enter the o omasum. The calf's nursing behaviour causes a reflex action that closes the oesophageal groove, which preve tering the rumen. e of the r (the vol me) drastically increases from birth with a massive growth spurt, significantly faster t the body. In the first weeks after birth the animal will get sufficient nutrition from the milk, but as the milk volu starts to decrease the young animal must get more and more absorbable nutrients from the rumen to make up e of milk. atest in fluence on rumen siz e and muscularization is the physical structure of the feed. To increase the rum The gr atest influence on rumen size and muscularisation is the physical structure of the feed. To increase the rumen size, the feed must have a larger particle size and highly effective The rumen h s five distinct yet connected compartments that create different niche environments. These subregions’ development is incorporated with the development of the rumen size. They have different fermentative profiles based on their microbial activity in these compartments. The microbe composition will cha ge based on these subregions, helping to improve effici nt food digestion that will impact the diversity of microbial populations inhabiting these regions. fibre to increase the physical stimulation of the rumen wall. This scratch factor will subsequently increase the rumen volume, the muscle in the rumen wall and the motility thereof. The physical structure of the feed will also help the rumen to increase the muscularisation (the process of smooth muscle cell accumulation) of the rumen wall and will increase blood supply to the rumen wall. A study showed that calves that were fed only milk showed signs of rumen motility at ten weeks of age, calves that received sponges showed signs of motility at seven weeks of age, but calves that received a grain-based diet showed signs of rumen motility at three weeks of age. We can, therefore, conclude that motility is not only a function of muscle development but that the nutrient value of the feed also plays a role. With the increased muscularisation of the rumen wall, we autom tically get an increase in blood supply. The incre sed blood supply plays a critical role in xygen and utrient s pply to the muscles, but they must also absorb and transfer the nutrients from the digestive tract to the body. www.agribonus.co.za Winter 2025 BONUS 43