Breeding to increase milk protein
Breeding can make a significant contribution to raising milk protein in the medium to long term. Channel Island and Ayrshire cows can produce milk with a higher protein content than Friesian/Holstein cows. Within any breed there are large variations in milk protein content and selection on the basis of positive protein deviation can improve milk protein production. The two key aspects of any breeding programme are dam selection and sire selection.
Dam selection based on milk records
It is important that breeding decisions are planned and based on reliable information as inseminations now will affect the quality of heifers entering the herd three years hence. The first requirement of a planned breeding programme is to know where you are starting from. Milk recording is an excellent means of identifying which cows in the herd are producing high levels of milk protein and those which are not. This information is vital in influencing which cows to breed replacements from and those to cull or replace.
Milk recording allows decisions to be based on facts
Sire selection
Choosing the cows from which to breed replacements from is only part of the story, selecting the right sire is also vitally important. Currently there is a large selection of bulls available on the market with information regarding their genetic potential. This information is provided in the form of profitability indices and predicted transmitted abilities (PTAs) which are intended as an aid to bull selection and they seek to define the benefits of a particular bull in monetary terms.
Profit Index (PIN) is the predicted additional margin over feed and quota costs, per lactation, that a bull is expected to pass to its offspring. It is calculated from the PTA (Predicted Transmitting Ability) values for weight of milk, butterfat and protein in the bulls proof. The latest addition to the list of indices is Lifetime Production Index (£PLI). This should prove to be a useful addition as it not only takes into account genetic merit in terms of milk, fat and protein production, but also those type traits which influence longevity and actual records of how long a bulls daughters survive.
A short list of bulls can be drawn up based on profit index and a final selection made on the basis of protein production. Selection on weight of protein (KG) alone will tend to reduce protein percent, likewise selection on protein percentage alone should be avoided as this will seriously reduce milk yield.
At Greenmount Campus the twin approach of dam and sire selection is used on the Protein Improver Herd. The top 50 cows from the Campus herd were selected in 1996 using milk records to identify those cows with the highest protein percentage. The best cows in the Protein Improver Herd have been bred to bulls with the following characteristics:
| Milk | >800 KG |
| Weight of protein | >25 KG |
| Protein deviation | >+0.05% |
| Reliability | >70% |
Bulls selected for use on the Protein Improver Herd have produced a batch of heifers calving in 1999/2000 with an average PTA for protein of 20.8 KG (+0.02 percent)
Is breeding for milk protein effective?
Milk protein percentage has a relatively high heritability of 40 percent, higher in fact than milk yield or weight of fat and protein (30 percent), therefore breeding to improve milk protein is both feasible and worthwhile.
The following example outlines the potential to raise milk protein in a commercial situation. The Poppy family has been established in the Greenmount Campus Protein Improver Herd through careful selection of sires to be used on cows with good milk protein records. The following are milk production details and PTAs from the members of the Poppy family.
Tirgracey Klaus Poppy
| Lactation | Milk Yield (KG) | Protein % | Butterfat % |
|---|---|---|---|
| 1 | 5531 | 3.37 | 4.19 |
| 2 | 7019 | 3.26 | 4.01 |
| 3 | 8326 | 3.34 | 3.75 |
Tirgracey Bert Poppy DOB: 20/9/93
Tirgracey Fatal Poppy DOB: 4/11/97
ITEM £79
Milk 506 KG
Protein 19.6 KG (+0.05 percent)
Butterfat 17.5 KG (-0.04)
| Lactation | Milk Yield (KG) | Protein % | Butterfat % |
|---|---|---|---|
| 2 | 6672 | 3.61 | 4.37 |
| 3 | 7067 | 3.51 | 4.41 |
| 4 | 5999 | 3.81 | 4.45 |
The aim of an effective breeding program should be to identify those cows with superior protein production potential. Ideally replacements should be bred from superior cows. Increasing the replacement rate will speed the rate of genetic progress and should, over time, improve milk protein production. This should be balanced by bearing in mind the cost of maintaining a high replacement rate.
- Milk record to identify cows with high milk protein yields from which to breed replacements.
- Breed replacements from cows with high milk protein yields.
- Breed replacements from cows with high milk protein percentages.
- Select well proven AI sires (reliability over 70 percent) with high PTAs for fat plus protein yields and high profit indices (ITEM, £PLI).
- From a shortlist of bulls with desirable PINs and conformation, select those with the highest protein percent deviation.
- Maintain a young herd. Aim for a replacement rate of 20% - 25%. This will increase the proportion of heifers in the herd, assisting genetic progress.
- Breed replacements from heifers.
