Cow and bull selection

Dr. Patrick Kelly

With calving coming to a slow down now it is time to start thinking about other on farm decisions.

From the early milk recording you can start making decisions on cows that should be getting dairy straws, beef straws or culled. Cows with high SCC or mastitis cases in the previous year need to be checked to see if they have cured or need to be culled. If they still have high SCC or mastitis in the same quarter then the need to be removed from the herd to protect the rest of the herd and the young heifers coming in. Cows that are after picking up mastitis need to be treated so they don’t become a problem. You can use your milk recording SCC figures to identify the cows to use the California milk testing paddle on, this will help to identify the quarter you are dealing with. If you have a lot of the same quarter being infected, flushing of the cluster between the cows when milking will slow down the transfer.

Moving on to the topic of breeding there are a few things to think about. With nitrates in place you need to know how much stock your farm can carry and how many milkers are going to be there going forward. This will allow you to identify how many replacements you need, either for your own herd or selling. When you know the amount you need, then you can pick the cows to get the replacement straws and the ones to get beef straws. Using beef straws early in your breeding season means you don’t have replacements coming from cows not performing in your herd.

You need to look at how the cows are performing across a number of traits:

• Fertility performance - Calving interval, going in calf early

• Production performance value – top 20 % of cows plus top cows from average group if needed

• Health – SCC, Lameness and Feet & Legs

Remember - Not all your young stock are your best genetics; a poor heifer out of a poor cow does not lead to a good replacement

The first step is do identify the cows in the bottom 20% using your milk recording. These are cows that you should not have replacements from. They are in your herd getting the exact same treatment as the top 20%, but there is a major difference in their performance value. Take the two herds to the right (Figure 1); one in the very high costs scheme (>9000kg) and the 2nd herd in a high cost scheme (7000 - 9000kg). There is €2.10 and €1.50 difference in the milk recorded margin per day respectively between their top and bottom 20%. This might not seem a lot per day but when worked out over a year it equates to over €700 and €500 per cow per year.

Table 1 above shows you the large difference between animals in the same parity for the bottom and top 20%. The top 20% are where you want your replacements from if they are fertile.

When you move into the 3rd and greater calvers they will not be in the top group without having good fertility. I cannot stress the importance of putting in the correct dry off dates to improve accuracy with all of these figures

Bull selection- What bull do you need?

This all depend on your herd status for fertility, production, health and functional conformation. Balanced bulls will get the best results. If you want to maintain the production level and percentages you currently have you need to select the bulls that are at the same level or slightly better. If you want to improve one of the production traits you need to select bulls with higher than your herd in that trait but on par with your herd in the other traits. The below are examples of herds PTA figures for production and fertility, these figure help when trying to match bulls with cows and improve the next generation.

From a functional conformation you need to be looking at the classification of the dams to ensure there is good linear behind the bull. The next step is to look at the conformation of the cow that suits your system, gives no trouble walking or milking. Then look at the other cows that you have selected as replacement dams compared to her, this will allow you to select the bull conformation that will best achieve the conformation of cow you want in the future. When selecting bulls look to make sure the bull is pedigree so this will

Provides sustained enhancement of the cow’s metabolism in the liver and rumen, and additional energy.

Energy and rehydration support ~ can also be given to calves around weaning.

Stimulates metabolism through fast, available energy.