When we think about feeding the cow, we are actually feeding the rumen bugs, the rumen bugs will then feed the cows. As dairy producers we must make full use of this, manipulating the rumen population and its end produce to meet the cow’s requirement for production.
Protein
The cow doesn’t have a crude protein requirement, instead, like monogastric, they metabolise amino acids (AA). Metabolisable Protein (MP) is the protein available for absorption by the animal in the small intestine, coming from a combination of microbial protein (60-65%) and protein that has not been broken down in the rumen, but is available for absorption in the small intestine -known as bypass protein, contributing up to 35% of MP supply.
Rumen degradable protein (RDP), can be supplied as nonprotein nitrogen (NPN) or true protein (Amino N as shown below in Figure 1). This is then broken down in the rumen to ammonia, which is used to create microbial protein as the rumen bugs multiply. The rumen bugs also need sufficient fermentable carbohydrates such as starch and sugar to feed the bug's energy. If there is much ammonia and insufficient energy, ammonia will build up and passes through to the bloodstream. Ammonia is toxic to ruminants so is converted to urea in the liver. There is an energy and metabolic cost to doing this which can affect performance.
UK diets are often based on grazed grass or grass silage as the main forage source. Although a great feed source and the cheapest available dry matter on the farm, these diets are unbalanced for generating MP. Grazed grass and grass silages are high in crude protein, from amino nitrogen and NPN, meaning there is an excess of ammonia within the rumen. The limiting factor for MP generation in these types of diets are often fermentable carbohydrates (starch and sugar).
Protein is one of the most expensive ingredients on the farm, so efforts should be made to capture as much quality protein as possible from grass to limit the need to purchase as much to supplement the diet. Due to the deficit in fermentable carbohydrates in the diet, we are losing metabolisable protein production, and wasting a lot of the protein which has been fed into the rumen, which was expensive to do so.
Addressing the imabalnce through supplementary feeding
Whether it is 0.5t/year or 3t/year of purchased feed, make sure it’s making full use out of your homegrown forage and is complementing the performance.
Increasing starch within diets is usually associated with increasing the risk of SARA (Sub Acute Rumen Acidosis), especially fibre sources are often replaced with starch to increase overall starch supply. Understanding Neutral Detergent Fibre (NDF) and how we can balance rumen fibre allows for higher rates of starch within our diets, without exposing the rumen to SARA and achieving higher MP production from less supplemental protein.
NDF analytics from Cornell University allows us to break NDF down into 3 pools allowing us the opportunity to balance accordingly with supplementation. Through understanding the degradability of the fibre sources, it is possible to increase starch within our diets safely capturing more of the nitrogen within the rumen, therefore being more efficient.
If we are unable to generate sufficient microbial protein from the rumen, the ration will be short of the MP requirement of the cow. At this time the use of rumen-protected proteins, through rumen-protected rape meal and soya, play a vital part in the diet. However microbial protein synthesis is the cheapest source of MP and we should realise this potential first.
The AminoMatch Concept
The AminoMatch concept is based on this theory to deliver what the cow needs in the most cost-effective and efficient way. Here are a few tips from the AminoMatch concept to ensure greater efficiency in the performance of the animals, financial performance and environmental efficiency;
- Capture as much protein form homegrown forage as possible
- Reduce the need to supplement purchased protein
- Increase fermentable carbohydrates within the diet
- Balance fibre pools
- Supplement bypass protein when necessary
Iwan Vaughan
Head of Dairy Technical Services
m: 07990 578548
e: iwan.vaughan@wynnstay.co.uk
@maesmochnant
