Ruminating cows receive digestive aid

Scientists at the Institute of Grassland and Environmental Research are developing new plant breeding techniques which can improve the efficiency of cow digestion and reduce pollution at the same time. Grass isn’t the easiest food to digest, and even cows appear to have difficulty doing it efficiently. Dr. Alison Kingston-Smith and Mrs. Rosalind Shaw will present results at the SEB annual meeting at Heriot-Watt University in Edinburgh outlining how selective plant breeding can improve the amount of protein retained when cows digest grass.

“Cows digest protein in their feed very inefficiently” explains Dr. Kingston-Smith “A lot of ammonia is excreted in their urine, resulting in nitrogen pollution on farmland.” Farmers usually attempt to fatten up their cows by feeding them high protein diets, resulting in unacceptable levels of nitrogen pollution. Dr. Kingston-Smith and her colleagues decided to examine grass itself to come up with a better solution. When cows eat, the grass is passed to the first stomach, which acts as a microbial fermenter that converts plant protein into microbial protein. The problem is that the enzymes in the ingested plants break the protein down too fast for the microbes in the stomach to be able to assimilate the products efficiently, so a lot is passed on before the microbes can retain it.

In order to find a way for the protein to be broken down more slowly, Mrs. Rosalind Shaw is studying a number of different species of grass that can hybridise naturally. She has discovered that rates of protein degradation differ enormously between these species. Her aim now is to find the part of the chromosome responsible for slow protein degradation rates in one species of grass and combine this desirable trait with the higher palatability of another grass species. The result: a tastier, easily digestible feed that fattens up the cows while reducing nitrogen pollution.