Culling Within The Dairy Herd

18 October 2018

Over this past year, farmers’ have experienced extreme weather conditions which have led to grass and fodder shortages rolling over into the coming winter in many parts of the country. The high cost of buying in fodder, with increased feed prices this winter will have a huge impact on the economics of many farm businesses. Forward planning will be key and assessing the herd on an individual animal basis, with the intention to take the best stock through the winter and into next year, is a realistic place to start, especially if forage stocks are inadequate.

Culling has a major impact on a farm and with this year’s cull cow trade being strong; this may be an opportunity for the business. Before culling, calculating the cost involved is vital as milk production, expansion efforts and profitability are all negatively affected when cull rates are too high. Ideally, culling should be an economic decision by removing one animal to replace it with one that is more profitable. However, if forage is in short supply, reducing numbers through culling and not necessarily replacing them may be obligatory.

With a recommended target cull rate of below 30% for a herd maintaining its size, there are many factors to consider during the decision-making process. A checklist should be made up which is specific to your herd. The main factors to consider when deciding which animals should be culled are:

Calving Intervals

Cows not in calf or those with extended calving intervals, especially if this reoccurs year-on-year, results in reduced annual revenue. A shorter dry period of 35 days tends to result in more problems relating to negative energy balance in cows. It is recommended that first lactation animals have dry periods of 60 days (Pezeshki et al., 2007) to avoid the risk of energy balance issues in early lactation as this can be detrimental to fertility.

Calving Problems

Poor fertility can be a result of cows having experienced metabolic disorders postpartum (e.g. retained placenta, metritis and milk fever) or a difficult calving such as internal tearing or a traumatic caesarean. Any infection or damage caused to the reproductive tract can affect the cow’s ability to get back in calf.

Low Fertility

The animals that have low fertility will require a higher number of services per conception which prolongs the period of time for the cow to get in calf or not at all, overall costing the business more money.

Mastitis

Cows that regularly suffer from chronic mastitis and do not respond positively to treatment can have an effect on reproductive efficiency as well as reduced milk yields. Cows that also have a high somatic cell count also increase the chances of mastitis spreading through the herd. It is recommended that cows which take mastitis in the same quarter within the same lactation are culled, as are cows which have at least 5 cases of mastitis (in more than 1 quarter) in the same lactation.

Overall Health

Undesirable traits such as lameness, aggression, udder shape, teat structure and placement and poor production can be other factors to consider when deciding which cows to cull. Comparing milk production against the herd average can be used to identify cull cows.

Culling should not be considered a substitute for solving any underlying problems that can be rectified by veterinary treatment or better management. However, considering key factors when culling cattle can economically benefit the business through better-time utilisation, reduced labour costs dealing with problematic animals and increasing the overall herd performance.

Reference

Pezeshki A, Mehrzad J, Ghorbani GR, Rahmani HR, Collier RJ, Burvenich C. Effect of short dry periods on performance and metabolic status in Holstein dairy cows. J Dairy Sci. 2007;90:5531–5541.

Gillian McMillan

Gillian.mcmillan@sac.co.uk

 

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