Farm Ireland

Sunday 25 March 2018

Only 5pc of recorded herds are achieving lactation targets

Most herds can't do anything about genetics
Most herds can't do anything about genetics

Nora O'Donovan

Cow fertility and longevity are critical components of herd profitability. While reproductive performance has improved in recent years, the average performance on Irish dairy farms remains below the optimum. Currently only 5pc of milk recording herds are achieving the target number of lactations.

The optimum average parity in a stable herd is 4.5 lactations, which equates to an annual replacement rate of 18pc. Expanding herds, with more heifers than normal coming in will have a lower number of lactations per cow. For these herds the average number of lactations per cow culled will give a more appropriate figure.

The reality is that a heifer will take an average of 1.63 lactations before she starts leaving any profit. Any heifer that leaves the herd before this has not fully paid off her rearing costs. National statistics show that 16.5pc of Irish cows do not survive beyond the mid point of their second lactation. At the current milk price, replacement costs is vitally important.

Recent studies in Moorepark show that genetic selection using the EBI will deliver improved performance and profitability under intensive grass based systems. The NGH herd is comparing the national average genetics (EBI of €133) to the top 1pc (EBI €249). The trends after two seasons are clear. The top 1pc are producing more milk solids with 14pc higher six and 12 week in-calf rates.

But excellent genetics will not compensate for poor management and likewise best management practices will not fully compensate for poor genetics.

Most herds can't do anything about genetics until next April. But body condition at calving has a big effect on getting cows back in calf next season.

The benefits are trouble-free calving, improved conception rates, reduced empty rates and increased milk solids production for the coming year. October is the time to focus on the Body Condition Score (BCS) and plans to get cows to the target BCS at calving which is 3.25. There are three main options for managing body condition.

Feed level and quality

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Make an effort to keep grass in the diet for as long as possible this autumn while setting yourself up to have grass available next spring. Test your silage now as quality will have an impact on both dry and milking cows. On good quality silage, cows will gain about half a unit of BCS over an eight week dry period. On poor quality silage cows will lose condition.

Length of Dry Period

The standard eight weeks dry will be enough where cows are at target BCS of 3 at drying off and silage quality is reasonable (68 DMD). Where cow condition or silage quality is below target an extra month dry is required. But where cows are thin and silage quality is poor a long dry period plus meal will be required.

Milking frequency

Once a day milking (OAD) is a proven method of improving BCS but needs at least six weeks to have an effect either pre drying or post calving. It is important to continue feeding as if cows were being milked twice a day. Avoid on cows with SCC higher than 200,000.

Heifers are the other variable effecting fertility which can be impacted by current management. Reaching the target weights is crucial to having heifers regularly cycling in time for breeding. Likewise achieving target weights at first calving will increase performance and conception rates as first lactation cows. This will result in increased longevity and overall profitability.

On good quality grass heifers will gain 1 kg/day. But once they go in on silage even with ration it's hard to get growth rates like this. Heifers should be weighed now and pick out the lightest for preferential treatment.

Some farmers are considering milking on cows into December to improve cashflow this winter. If body condition suffers, this will have a negative impact on farm profitability far beyond next spring.

Likewise this is not the winter to carry surplus heifers with a portion of them not reaching target weights for breeding next year.

Nora O'Donovan is a Teagasc advisor based in Tralee, Co Kerry

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