Farm Ireland
Independent.ie

Tuesday 6 December 2016

Ensure body condition remains focus for dry cows

Dairy

Mary Kinston

Published 30/11/2011 | 06:00

With the milking season over on most spring-calving farms, herds of dry cows -- either housed or being wintered on crops -- are now a common sight across the country.

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It's a nice time of year to slow down and reduce the length of the working day, especially with the short day lengths. However, there is the risk that the dry cow can be managed by neglect. The fact that the dry cow period has the lowest nutrient requirements has given farmers the wrong impression of the importance of this period in terms of cow health and future production.

The importance of body condition score at calving has been known for decades. Calving a cow at a score of 3.25, where the backbone is smooth, ribs are flat and not easily felt, the pin and hip bone is rounded and the tail head is full and firm (heifer at 3.5 -- tail head full and obviously fat but ligament visible), is optimal for both milk production and fertility. Getting this wrong could cost you dearly, with research suggesting a loss of milk equating to 112-224 litres per cow over first eight weeks, along with a longer anoestrus period, and 7pc higher infertility rates.

These figures may seem small but the reality of an empty rate of 8pc after 12 weeks of mating, compared to 15pc, is substantial.

Yet, at farm level most farmers are still struggling to find strategies that both monitor and guarantee that 95pc of our cows reach this target of 3.25 a month prior to calving. Obviously, late lactation strategies, such as early dry off of low condition-scored cows and first calvers or increased and preferential feeding of cows in late lactation, can help. The following are key management strategies to help you hit those targets:

•Act early as a target of 3.25 needs to be achieved before the last month of pregnancy. Cows calving in early February now only have 30 days to gain an adequate body condition.

•Identify cows by calving date, split off low-conditioned cows and preferentially feed these animals.

•Keep younger and lighter cows apart to reduce competition with mature, heavier cows.

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•Make sure transition onto and off a crop or different feed straights, such as rolled barley, is done gradually.

•Have a timely dosing and vaccination schedule to promote good health and a gain in condition. Use diagnostic sampling where appropriate to identify issues that are causing ill thrift.

•Feed a diet adequate in both amount and quality to promote the desired amount of condition score gain.

•Consider small changes to infrastructure or the feeding management on a crop to facilitate having different groups, adequate feeding space, or batch feeding.

When it comes to the debate about what to feed, when and how much, it can get quite complicated. However, we can assume that a cow can maintain herself and her present condition score on silage only. This will equate to 8kgDM/day for a cow in her seventh month of pregnancy. This will then rise to around 9.5-10kgDM/day in the ninth month of pregnancy. To increase condition from 2.8 to 3.25 requires a gain of 33kgLW for a 500kg cow and to 36kgLW for a 550kg cow, while 68MJ ME is required per 1kgLW gain. If we assume silage quality is 10.5MJ ME/kgDM, a cow needing to move up 0.5 of a condition score is likely to require an extra 214-233kgDM of feed over the course of her dry period. This is no small amount of feed and over 60 days equates to an extra 3.5-4kgDM/day/hd and would boost intake requirement to 11.5-12kgDM/day at seven months. However, if this condition score gain is required over one month, an extra 7-8kgDM/day is needed and intake would have to rise to 15-16kgDM, which is challenging on silage alone. Therefore, the diet quality needs to improve, and feeding a concentrate or ration of higher quality is required in this scenario. Around 3-4kgDM may be necessary over a short period.

At the other end of the spectrum, there is the risk of some cows getting too fat and calving above 3.5. This has little effect on milk production but it increases the likelihood of milk fever and ketosis.

Also, it's vital to provide adequate magnesium for a minimum of four weeks pre-calving to reduce any metabolic issues.

Dr Mary Kinston is a farm consultant based in Kerry. Email: mary.kinston@gmail.com

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