Liver function in dairy cows in late pregnancy and early lactation

Abstract

During early lactation, the dairy cow has to contend with a variety of factors which can lead to impairment of hepatic function. Studies have shown that since the overall energy requirement is greatly increased, rates of metabolic processes within the liver have to be increased in proportion. Priority appears to be given to the nutrient requirements of the foetus during gestation and to the lactating mammary gland in early lactation. The cow may be in a state of negative energy balance as peak milk yields are reached 3 to 7 weeks after calving whereas peak voluntary food intake is not reached until 8 to 10 weeks after calving. Hormone production is such as to encourage lipid mobilization. As a result of this energy deficit, cows mobilize their tissue reserves for milk production and may lose appreciable amounts of body weight and muscle. Similar factors may also pertain in late pregnancy.

One of the possible consequences of mobilization of body reserves is the development of a fatty liver. It was estimated that up to a third of high yielding dairy cows in the U.K. were affected by consequence of fatty liver. Substantial mortality may occur as a consequence of fatty liver in dairy cows and complications such as chronic ketosis, parturient paresis, displaced abomasum, retained placenta, endometritis, an impaired immune response and an adverse effect on fertility have been reported.

The purpose of this investigation was to establish any changes that may occur in liver function in periparturient dairy cows, when compared with non-lactating cows, in order to aid identification of the cows which are likely to develop fatty liver.