Introduction
Low levels of milk protein have long been recognised as a major limiting factor in the competitiveness of the dairy sector in Northern Ireland. The problem is especially acute in that approximately 85 percent of the milk produced is destined for processing where compositional quality is much more important than for the liquid market. In contrast to butterfat, increasing milk protein production is not constrained by quotas and provides an attractive means of increasing the value of each litre of milk produced.
Dairy products are a rich source of protein
Milk proteins contribute directly to the nutritional value and the physical characteristics of many dairy products, and also can affect the actual amount of product manufactured. Dairy products are a rich source of protein and play an important role in the diet.
Factors influencing milk protein content
Milk protein concentration is influenced by many factors including:-
- Nutrition - The overall energy intake and the type and quality of foods offered to the cow has a major impact on milk protein production.
- Breed/Strain - Channel Island and Ayrshire cows produce milk with a higher protein content than Friesian/Holstein cows. Variation within a breed is also substantial.
- Stage of lactation - Milk protein content is high at calving, falls rapidly to a minimum at peak yield and gradually improves when the cow is back in calf and yield declines.
- Age of cow - Dairy cows generally produce their highest milk protein in the first lactation, with a decline of 0.05 percent between the first and fourth lactation.
- Seasonal effects - Late winter low milk protein from the autumn calving cow normally results from the combination of stage of lactation effects and declining nutritional status over the winter.
