BECOMING A RUMINANT IS NOT OBVIOUS


Credit : Sophie Dale

The gastro intestinal tract of a calf is not fully developed at birth. Calf is considered physiologically as a monogastric as his rumen become truly functional only after the weaning. This pre-weaning period must prepare the calf to become a ruminant and maximize the development of his rumen in term of feed intake and absorption capacity for a productive future life. The length of this period is heavily diet-dependant. Furthermore, this time is risky in term of health control and stays expensive due to specific feed and time-consuming management. We will see however that those expenses can be wise investment. Calf development is very particular and misconceptions remain strong on the field


Vietnamese version



Why a calf doesn't born as true ruminant?


During nine months of gestation, the cow feeds his calf throughout the placenta with very simple nutrients. There aren’t in utero microbe’s transmissions from cow to calf. Rumen is small and sterile at birth and rumen papillae are nearly absent.


In early life, all digestive process will take place in the stomach or abomasum. The oesophageal groove is a curved muscle that lies in the throat of the calf. Milk can bypass the rumen and go directly in the abomasum. There, milk is coagulated by calf specific enzyme and is digested. Oesophageal groove is activated only with warm milk (40°C). If milk is cold, it ends up in the rumen and leads to lactic fermentation and diarrhoea. Thanks to vaginal flora and mother’s licking reflex after calving, rumen microflora will be seed in the calf. This licking is essential for the future rumen development. Rumen is contaminated with both aerobic and anaerobic flora and the challenge will be to develop the anaerobic one.

Proportion of different stomachs in the calf’s gastro intestinal tract change quickly after birth (figure1). Rumen is going to be fully functional after 4 months. Objectives for functional rumen are:

  • Acquires motility

  • Increase size

  • Develop absorption capacity

  • Set up the microflora



Figure 1: Proportion of different part of calf's stomach (From A.Ferran)


Motility and size are acquired with physical stimulation. Milk doesn’t develop motility and that explains the necessity to offer dry feed shortly after birth. This feed could be dry roughage or concentrate but it is much more relevant to start the feeding with a specific calf starter diet. Actually, chemical stimulation of the rumen is more important than the physical one at the beginning. The physical stimulation from pellet is enough and necessity of roughage before weaning remains highly controversial… Fermentation of concentrate by microflora resulting in a higher supply of volatile fatty acid (VFA): acetate, propionate and butyrate. Those VFA are essential for feeding the rumen microflora and develop ruminal epithelium. Importance of early distribution of calf starter feed Microbial fermentation of carbohydrates in the rumen is the most important source of butyrate for ruminants. Up to 90% of ruminal butyrate is absorbed directly from the rumen and most of this pool is metabolized by ruminal epithelium as an important source of energy. Infusion of butyrate in pre ruminant calves increase epithelial cells proliferation, length of papillae and reduce apoptosis. Sugar and starch are efficient precursors of butyric acid and propionic acid. Feeding a diets high in starch and sugar after the colostrum intake is highly recommended to speed up the development of forestomach in preruminant calves. A famous study was done by PennState University, you will see a comparison of various stomachs development for different diets at 6 weeks of age. We clearly see that the diet with milk + concentrate shows the better villi development. Calf starter is absolutely necessary to develop the rumen and must be available from the third day of life.



Milk only

Milk + Concentrate