Farm Ireland

Sunday 25 February 2018

Drying off is key for milk yield and cow heatlh in '14

Dr Siobhan Kavanagh

The dry period is a rest phase in the lactation cycle of the cow. The objective is to set up the cow for a trouble free transition to the next lactation.

A good dry cow management strategy will have a positive impact on milk production, colostrum quality and calf health, reduced incidence of metabolic problems during the transition phase and better fertility results.

This year, given current milk price, the temptation may be to continue milking cows over the winter in some parts of the country, shortening the dry period.

However this could have a double negative effect on cow condition, subsequent milk yield and fertility.

The opposite also holds true. Extended dry cow periods, due to quota issues or late calving cows, can result in over conditioned cows.

Length of the dry period

Cows should have at least an eight week dry period in preparation for the next lactation. This may need to be extended if cows are in very poor condition.

Managing body condition score

Also Read

The target body condition score (BCS) at calving is 3.25 for dairy cows, with an acceptable range of 0.25 above or below this point.

Figure 1, right, shows the effects of under-conditioning, including low milk yield and anoestrus, while over-conditioning will cause milk fever and ketosis.

The rule of thumb is that every half a condition score (0.5 BCS), equating to approximately 25kg in bodyweight, that a cow is below target at calving results in a 225-litre drop in milk production in the following lactation and reduced fertility.

Act early to manage BCS

Take stock of your herd early to make changes in time.

The following points will help you decide how and when to act:

* Herd average BCS is not particularly useful for herd management. Focus instead on using BCS of individual animals and make decisions on a cow-by-cow basis.

* Check the body condition score of the herd at least 14 weeks before the beginning of the calving season.

* Write down expected calving date for each cow.

* Assign each cow to a management plan to meet target BCS using one or more of the tools available. Batch cows according to cow condition.

* Internal parasites and lameness have a negative impact on the cow's ability to achieve target BCS.

Implement a parasite control programme and treat any lame cows in the herd.

Managing cow condition

The main tools for BCS management during the dry period are:

1.Feed intake and quality

Feed energy (UFL) intake drives BCS gain in the dry period. In the dry period, poor quality silage has a double effect of poor dry matter intakes and low energy content.

The aim should be to maximise energy intake from silage. Check the quality of your forage and aim to feed grass silage of 68pc dry matter digestibility (DMD) to the dry cow.

Supplementation of the dry cow will be driven by BCS, length of the dry period and forage quality. Guidelines on supplementation rates during the dry period based on forage quality and BCS are outlined in Table 1, left.

As a guide, cows at condition score 2.5 need 12 weeks dry and, if being fed 68DMD silage, need 1kg of supplementary meal.

2.Dry period length and days in milk

At the standard 60-75 days dry, cows at BCS 2.75 drying off and eating reasonable quality (68-70 DMD) silage will be at target BCS calving down. Allow at least 30 extra days dry where BCS and/or silage quality are below target.

This would mean drying off in late October for early February calving, mid-late November for March calving and mid-December for April calving.

Table 2, below, outlines when cows need to be dried off, depending on the required length of the dry period.

For example, if expected calving date is February 1, thin cows that need 12 weeks dry, should be dried off by November 2.

Siobhan Kavanagh is an animal nutrition specialist with Teagasc.

Irish Independent