Food Conversion Efficiency is often misunderstood and overlooked, despite its role in profitability.
How much milk a cow produces at any time in the lactation will be influenced by a myriad of factors including genetics, stage of lactation, lactation number, amount and types of feed eaten, walking distance and climatic factors. It would be impossible to discuss all these in one article so I’m going to look at a few common nutrition related reasons why cows underperform relative to farmer expectations or compared to the herd next door.
The amount of energy a cow can eat determines how much milk she can produce.
Bigger cows eat more and therefore produce more milk. Typical peak drymatter intakes for pasture-based cows are in the range 3.2 – 3.5 %1 of bodyweight, while cows on a total mixed ration can eat as much as 3.8 %2 of their bodyweight.
I have heard farmers say their 450kg Kiwi-cross cows are eating 18-19kgDM, so they should be producing more milk. The reality is, these cows might be offered 18-19kgDM, but it is highly unlikely they are consuming this much pasture.
For most New Zealand herds energy is the key limiting factor to achieving higher milk yields (see table 1). In many cases the issue is the amount of feed offered rather than the amount or quality of feed the cows can physically eat that limits production. In saying that, in pasture-based systems there is a close relationship between pasture allowance, pasture intake and pasture utilisation. Offering more feed will result in higher intakes but pasture utilisation will be reduced. As pasture utilisation decreases, residuals rise and pasture quality falls. Lower pasture quality means lower intake and therefore lower milk production.
Feed quality plays a crucial role in determining milk production levels. Higher energy pastures and supplements will generally deliver higher milk production levels than lower quality feeds, providing the diet contains enough fibre to maintain rumen health, and protein and minerals are not limiting.
If your cows are underperforming, first look at the total drymatter intake then consider the quality of the feed being offered, starting with those feeds being fed in the highest volume. Often supplements get the blame for poor production, when the key issue is either too little pasture or poor quality pasture. This is particularly relevant at this time of year when pasture heads into its reproductive phase and quality declines.
If you are chasing really high production make sure you test the quality of supplements and pasture on a regular basis. Rations should be put through a ration-balancing programme to ensure cow nutrient requirements are being met.
Well conditioned cows produce more milk than cows that are too skinny or too fat. The target body condition score at calving is 5.0 for mature cows and 5.5 for first and second calvers.
Cows calving 1 BCS lower than target will produce about 15kg less milksolids the following lactation. They will take 8-10 days longer to start calving, resulting in a later calving date next year.3
At a $5.30/kgMS payout the extra production generates a return of $80 per cow, or $24,000 for a 300-cow herd.
Maize silage is one of the best systems feeds for producing more milk. It is a high-energy silage which can be used to plug feed deficits, increasing lactation persistence and days in milk. It can be fed on a feed pad when either there is not enough pasture or when the soil is wet and is therefore in danger of being pugged. Energy from maize silage is used 50% more efficiently for condition score gain than energy in autumn pasture. Because of its high starch content, maize silage produces more milk protein and less milk fat than a more fibrous feed like PKE.
1Glassey et al. 1980. New Zealand Society of Animal Production 40:59
2Kolver, E.; Muller, L. 1998. Performance and Nutrient Intake of High Producing Holstein Cows Consuming Pasture or a Total Mixed Ration. Journal of Dairy Science. 81: 1403–1411
3DairyNZ, 2010. Facts and Figures for New Zealand Dairy Farmers.