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Is High Genetic Merit Semen Value for Money?

Milk Manager Results

The average AI fees for a farmer using Milk Manager was £16 per cow in 1995/96. This masks the fact that individuals had costs of £60 while others used a stock bull and recorded no AI fees. The cost of producing a heifer calf can be substantial. If it is assumed that it requires 4 straws of semen to produce 1 heifer, semen costs of £100 plus are possible even without using "top of the range" sires. The question must be "is this semen value for money?".

Milk Manager results do not show a correlation between yield per cow and AI fees. This of course is a very crude measure of value for money as it does not take into account milk quality or the fact that semen used today will not influence milk production for a number of years.

Profit Index

The development of PIN for dairy sires was intended not only as a bull selection aid for farmers but also to put in monetary terms the benefit of using a particular bull. PIN is defined as the predicted additional margin over food and quota costs, per lactation, which the bull is expected to pass to its offspring. PIN assumes that protein achieves 1.5 times the value of fat per kilogram and that quota leasing is at 6 pence per litre. The proposed United Dairy Farmers payment scheme for 1997 will pay a 1.78:1 premium for fat over protein while quota leasing has traded in excess of 12 pence per litre for most of this quota year. There are now a large number of different payment schemes for milk and it would be impossible to cater for all of them. The other point to note is that the cows produced from bulls used today will be milking after the year 2,000 when the quota regime may have changed or gone completely. A weighting is given to the various elements in the PIN formula to give an overall value for a bull. The formula is as follows:

PIN =

  • PTA 95 Milk (kgs) * -0.03 +
  • PTA 95 Fat (kgs) * 0.60 +
  • PTA 95 Protein (kgs) * 4.04

Relative breeding index

RBI is the equivalent formula used in Southern Ireland. It is as follows:

RBI =

  • 100 +
  • PTA 95 Milk (kgs) * -0.014 +
  • PTA 95 Fat (kgs) * 0.36 +
  • PTA 95 Protein (kgs) * 1.64 +
  • PTA 95 Protein (%) * 74

It can be seen that RBI will select for bulls with higher protein percentages due to the high weighting in the formula. This is demonstrated by the following two bulls:

  • Bull B
    • Milk+549kgs
    • Fat+31.6kgs(+0.18)
    • Protein+26.0kgs(+0.15)
    • PIN 107
    • RBI 157
  • Bull A
    • Milk+1220kgs
    • Fat+30.8kgs(-0.29)
    • Protein+38.0kgs(-0.02)
    • PIN 135
    • RBI 155

Index of Total Economic Merit

ITEM is a refinement of PIN which takes into account the longevity of a particular sire’s progeny. Longevity is correlated with foot angle, teat length, angularity and udder depth. These are all given a different weighting in the formula. ITEM is to change in 1997 with the dropping of angularity from the formula. PTA’s for longevity and SCC will be published in a bull’s proof and these will be incorporated into ITEM. The best value for money in bull semen will be obtained by selecting the highest ITEM sire that you can afford.

Langhill Results

Experimental work in Scotland has calculated that an extra 1 kilogram of combined fat and protein in a bull’s proof is worth £2.60. This has been calculated using the following assumptions:

  • 4.4 straws to produce 1 heifer
  • 3.35 lactations per cow
  • 5.8 years is the average time when returns from the semen used today occur
  • A bull used today will influence a herd for 10 years.

Using this calculation, virtually all bulls now available are better value for money than using a bull with a PTA of zero. This calculation should help when choosing between two bulls. For example, bull A above has 11.2 kilos more combined fat and protein than bull B. Thus the difference in the bulls is worth £29 per straw of semen to the farmer. If bull A is £35 more expensive than bull B, bull B would be better value. Similarly if bull A is £20 more expensive than bull B, bull A would be better value.

Investing in Dairy Genetics

Thus, although semen may seem expensive, in most cases high merit bull semen will give a good return on the "investment" made. There are a number of different indices which can aid the farmer in choosing a bull. The refinements to ITEM in early 1997 should make it the best figure to use when selecting a bull. If the choice is narrowed to a small number of bulls, the final selection can be made by valuing a kilogram of fat and protein in the bull’s proof at £2.60 per straw of semen.