Abstract
Three main preventive principles against milk fever were evaluated in this literature review, and the efficacy of each principle was estimated from the results of controlled investigations. Oral calcium drenching around calving apparently has a mean efficacy of 50%–60% in terms of milk fever prevention as well as prevention of milk fever relapse after intravenous treatment with calcium solutions. However, some drenches have been shown to cause lesions in the forestomacs. When using the DCAD (dietary cation-anion difference) principle, feeding rations with a negative DCAD (measured as (Na + K) – (Cl + S)) significantly reduce the milk fever incidence. Calculating the relative risk (RR) of developing milk fever from controlled experiments results in a mean RR between 0.19 and 0.35 when rations with a negative versus positive DCAD are compared. The main drawback from the DCAD principle is a palatability problem. The principle of feeding rations low in calcium is highly efficient in milk fever prevention provided the calcium intake in the dry period is kept below 20 g per day. Calculating the relative risk (RR) of developing milk fever from controlled experiments results in a very low mean RR (between 0 and 0.20) (daily calcium intake below versus above 20 g/d). The main problem in implementing the low-Ca principle is difficulties in formulating rations sufficiently low in calcium when using commonly available feeds. The use of large doses of vitamin D metabolites and analogues for milk fever prevention is controversial. Due to toxicity problems and an almost total lack of recent studies on the subject this principle is not described in detail. A few management related issues were discussed briefly, and the following conclusions were made: It is important to supply the periparturient cow with sufficient magnesium to fulfil its needs, and to prevent the dry cows from being too fat. Available information on the influence of carbohydrate intake, and on the effect of the length of the dry period and prepartum milking, is at present insufficient to include these factors in control programmes.
Highlights
Milk fever, the clinical manifestation of parturient hypocalcaemia, is a disease of considerable importance for dairy cow welfare and economy
Oral calcium drenching is recommended as a supplement to intravenous therapy for the prevention of milk fever relapses (Table 2)
The extensive urinary calcium excretion seen in cows fed anionic salts, may stimulate the vitamin D-related calcium homeostatic mechanisms, and in this way help prevent parturient paresis (Vagoni & Oetzel 1998) Fig. 1 shows the incidence of milk fever obtained in experiments applying feed with different dietary cation-anion difference (DCAD)
Summary
Milk fever (paresis puerperalis), the clinical manifestation of parturient hypocalcaemia, is a disease of considerable importance for dairy cow welfare and economy. Oral calcium drenching is recommended as a supplement to intravenous therapy for the prevention of milk fever relapses (Table 2). In this case a programme involving 1 or 2 doses is most often recommended. As discussed below, such calcium chloride drenchings were later discovered to have a prophylactic effect when given according to a programme covering the peak of the risk period. Preventive effect on milk fever1) (MF incidence in experimentals vs controls, %). The calcium solution thereby avoids dilution within the rumen, and a high concentration gradient would be obtained in the abomasum favouring passive Ca transport (Goff & Horst 1993).
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