Relationships between size, live-weight change and milk production characters in early lactation in dairy cattle

Abstract

Live weight, milk yield, fat, protein and lactose percentage of 236 cows and heifers of four breeds of dairy cattle were recorded at 2-week intervals, starting within a week after calving, during the winter and spring of 1972/73. Lactation curves of the form X(n) = Xn b e cn were fitted to each animal's records, where X, b, c are constants, e the base of natural logarithms and X(n) the value of the character at the nth 2-week interval. Correlations between the curves, and between deviations from the curves, showed that the production of milk, fat, protein and lactose was negatively correlated with live-weight change in the long term, but that deviations from the curves were not correlated. There were significant positive correlations between milk yield and size, and between potential compositional quality and size (the values of X in the model). Of the four breeds studied, Friesian, Ayrshire, Guernsey and Jersey, adult Friesian cows required less dietary energy per kg of total solids produced than any other group, according to the principles of the metabolizable energy system of calculating energy requirements. During the period of negative energy balance, an average 10% to 15% of energy output in the form of milk was derived from the mobilization of body reserves.

Empirical algebraic modelling of live weight of Irish dairy cows over lactation

“…The effect of environmental and seasonal factors, independent of stage of lactation, was also examined. The models under consideration were the models of Wood et al (1980), Wilmink (1987) and Guo and Swalve (1995) (see Table 1). These models were fitted to data which were pooled across animals and days-inmilk using nonlinear regression and the effects of lactation number, calving month, herd and total milk yield were removed from the parameter estimates.…”

“…In contrast to the modelling of lactation curves for both milk production and composition, relatively few researchers have contributed to the progression of work in modelling patterns in live weight change of individual animals; Wood et al (1980) examined the live weight changes of several breeds of British dairy cows using an incomplete gamma function. However, this analysis was restricted to the first 20 weeks after calving.…”

“…Korver et al (1985) constructed a function from the incomplete gamma function incorporating live weight level (scale), together with variables representing pregnancy status, the maximum decrease of live weight during lactation, and the time during lactation at which minimum live weight occurred. Berglund and Danell (1987) and Lopez-Villalobos et al (2001) also used the model of Wood et al (1980) to predict live weight change in their respective studies.…”

“…The principal model to describe live weight over a lactation is the model of Wood et al (1980). As this model form was previously used to describe milk yield, other models that were used by Quinn et al (2005) to describe milk yield were also investigated.…”

Dehydration as a risk factor for calf mortality in northern Australia

“…In dairy cows, during the negative energy balance experienced during early lactation, an average of 10% to 15% of energy output in milk was derived from the mobilisation of body reserves (Wood et al, 1980). For dairy cows in early lactation, the conversion efficiency of energy within body reserves to milk energy was 82-84% (Moe et al, 1971).…”