NUTRITION ▶▶▶
Rumen at the heart of feed efficiency
BY JUSTINE LAISEMENT, PRODUCT MANAGER AT MIXSCIENCE F
0.26 0.27 0.28 0.29 0.30 0.31 0.32
0.23 0.24 0.25
*Valopro
eed efficiency can be defined as the ratio between performance and feed consumption. In dairy farming, performance can be expressed by Energy Corrected Milk (ECM), which takes into account milk yield, but
also protein and fat contents. Feed consumption is commonly expressed in kilogrammes of Dry Matter Intake (DMI).
What can explain variation in feed efficiency? Important variation in feed efficiency can be measured among animals and numerous possible causes have been identified. This includes days in milk, body weight change, ac- tivity, etc. However, main factors are linked to feed itself: diet composition, raw materials digestibility – especially forages – as well as distribution, palatability or rumen passage rate. Ru- men is actually the keystone of feed efficiency: it is the main first organ of the cow digestive tract. This large vault harbours a wide microflora population responsible for nutrient diges- tion and distribution to the host organs and tissue. Rumen, in
Figure 1 - Results of trial in Holstein cows. Protein efficiency
= Milk Protein content (kg) / Crude Protein Intake (kg)
1.05 0.31 1.00 0.95 0.90 0.26 0.85 0.80 0.75 Control Product A* 0.85 1.00
The rumen is actually the keystone of feed efficiency: it is the main first organ of the cow digestive tract. What can be done to further optimise it?
association with the reticulum, is indeed a very effective fer- menter that breakdown diet constituents: starch, cellulose, protein and, to a lesser extent, fat. Among the multiple pro- cesses happening in the rumen, two main outcomes are ex- pected from rumen functioning: Volatile Fatty Acids (VFA) and Metabolisable Protein (MP). Improving feed efficiency, from rumen perspective, means a maximal availability of these two nutrients in the intestinal tract.
Effect of feeding practices Dairy farmers have historically fed diets with a protein level beyond cow requirements, notably to counteract a naturally poor use of proteins by the cows. Indeed, research has demonstrated that usually less than 30% of protein intake can be retrieved in milk protein content form. Such practice can also be advised by nutritionists in order to provide
Energy efficiency = ECM (kg) / Net Energy Intake (kg)
1.20 1.25 1.30 1.35 1.40 1.45 1.50 1.55 1.60 1.65
Feed efficiency = ECM (kg) / Dry Matter intake (kg) 1.62
1.37
▶ DAIRY GLOBAL | Volume 5, No. 4, 2018
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