The Importance of Dairy Cow Body Condition at Drying Off

September 1, 2021

Dr Jane Sayers, CAFRE Dairy Development Adviser, continues on from her guidance on how to dry off dairy cows with a focus on body condition scoring (BCS). Jane says that BCS is a useful tool to minimise problems post calving and advises that “ideally cows should be dried off at condition score of 3 and maintained at this level until calving.  At this condition score, the cow will be able to mobilise her body reserves in early lactation to meet the extra demands of milk production”. 

Jane suggests that “cows which calve down in poor condition, that is BCS less than 2.5, are unlikely to achieve their full genetic milk yield potential and are prone to lower fertility performance”.  It may be beneficial to feed these cows extra energy via concentrates in late lactation to allow them to gain condition.  Lactating cows utilise energy 25% more efficiently for live-weight gain than dry cows so late lactation is an ideal time to improve body condition.  A longer dry period should also be allowed. 

Jane advises that “over conditioned cows are particularly at risk of suffering from metabolic issues such as milk fever, and the goal is to have cows fit but not fat.  There will be a range of body conditions in the cows you are drying off, so it is beneficial to split them into groups and feed accordingly”.

At CAFRE Greenmount Campus cows with condition score 3 are offered bulky forage which is sufficient to maintain condition and keep the rumen expanded and working.  Thinner cows, BCS less than 2.5, receive better quality silage plus 2 kg maize meal per day.  A rule of thumb is that every condition score (equating to approx. 50 kg) below target at calving results in the cow producing 450 litres less milk during the lactation and having reduced fertility. The reduced milk yield can have a financial cost of around £135 per cow in lower milk sales (based on 450 litres x 30ppl).

Nutritional considerations for the dry period

The dry cow’s diet should be balanced to meet her nutritional needs and that of the developing unborn calf.  The total protein content of the diet should be 12 – 14%.  The energy requirements of the cow plus developing calf increases from 95 MJ/day in the early dry period to over 120 MJ/day approximately 3 weeks before calving.  This is at a time when the cow’s dry matter intake declines.  Consequently the nutrient density of the diet must increase to support the cow’s protein and energy needs.  This is usually done by supplementation with a suitable pre-calver concentrate. 

Dry cows should be fed forages which are low in potassium (K) to minimise milk fever risk. Choose grass or silage grown on an area where the soil is low in K or use whole-crop cereals. A mineral analysis can determine the level of milk fever risk for the particular forages being fed. Remember, ‘close-up’ cows should be housed a minimum of three weeks before calving, as grass is particularly high in potassium. Throughout the dry period cows should be supplemented with dry cow minerals.

Jane summaries that successful dry cow management should address the key issues of the length of the dry period, dry cow treatment, body condition and nutritional management. Care taken with assessing body condition score and feeding the dry cows carefully throughout the dry period will pay dividends in the subsequent lactations. For further information and advice on any aspect of dry cow management contact the local CAFRE Dairying Adviser.