Dry Cow Nutrition & Management

Although cow condition should be over four at drying off, there may still be a window of opportunity during late autumn and winter for cows to regain some condition and prepare for calving and early lactation. It is not easy to put on condition during the latter part of the dry period, as foetal growth increases exponentially, such that its needs are equivalent to about 50% of their mother’s. For example the maintenance energy requirement of cows is about 60 MJ ME/day, and the foetus just prior to calving is about 30 MJ ME/day. This would require about 10 kg DM of forage supplying 10 MJ ME/kg DM.

About 30 MJ are required to gain a kilogram of bodyweight, with one condition score being equivalent to about 25 kg LW for Jersey or 40 kg for Friesian cows. Therefore, gaining say 0.5 kg LW a day during the dry period increases cow requirements considerably at a time of increasing foetal demand, and declining appetite close to calving. Cows that are either too fat or too thin at calving tend to have more problems at calving, cycle later and are more difficult to get back into calf than cows calving with condition scores of about five. Later calving cows tend to have shorter lactations, resulting in losses of income of at least $5 for each additional empty day.

A number of factors influence how soon cows start to cycle after calving namely, nutrition and condition score prior to calving, ease of calving, nutrition and metabolic issues after calving, disease and stress. Essentially, cows should be well fed prior to calving remembering that responses to trace minerals are not immediate. Thin cows are likely to have longer calving to first oestrus intervals, and fat cows are more likely to become ketotic, through inadequate voluntary feed intake after calving.

The three weeks immediately before and after calving (transition period) have a major bearing on subsequent milk production and fertility rates. Poor feeding and management during this period can result in a host of problems around calving such as dystocia (difficult calvings), retained placenta, milk fever (hypocalcaemia), grass staggers (hypomagnesaemia), rapid weight loss and ketosis.

Many of these issues are related as one may lead to manifestation of the other conditions, due often in part to depressed feed thus nutrient intakes. Costs arising from these conditions are usually calculated based on clinical cases. However, loss of income arising from lower milk yields and delayed pregnancies with sub-clinical cows is more important, bearing in mind there may be 10-15 sub-clinical cases for each clinical case.

Cows need to be fed good quality feeds containing adequate long fibre according to condition during the dry period, to minimise the risks highlighted above. Suitable mineral supplementation (magnesium, trace minerals) should be part of the feeding regime. A separate “springer cow” diet should be implemented during the 2-3 weeks before calving. This should include similar feeds to those fed after calving to allow the rumen microbial population to adapt to changes in nutrient supply. Cows obtain about 80% of their energy and protein supplies from volatile fatty acids arising from microbial degradation of feeds and digesting microbial protein respectively. Therefore, it is important to ensure microbial activity is optimised when feed intakes are depressed.

Magnesium chloride and sulphate (anionic salts) are preferable to magnesium oxide during this period in helping to reduce the risk of milk fever at or soon after calving. There may also be a need to feed some vitamin D to cows with low pasture intakes, as this vitamin along with magnesium is important in mobilising calcium from the bones after calving, where about 80% of calcium reserves are stored. Trace minerals should also be fed, as these are important components in many metabolic pathways involved in energy utilisation, health and fertility. Although good nutrition is very important for good production, fertility and health, it needs to be combined with good stockmanship, facilities, hygiene and management.