Body score of dairy cows.

Body CS measurement, based on a standardized technique leading to a numerical assessment, provides a cheap, easily applied measure of fatness in cattle and hence an immediate absolute appraisal that avoids the problems of live weight. The scale is limited and the divisions are coarse. The nutritional significance of CS/C has received considerable research attention. Higher CS/C is associated with smaller feed intake in early lactation, increased loss of CS, increased fat content of milk, especially when the general content is low, and slightly reduced milk protein content. Evidence on the effect of CS/C on subsequent MY is conflicting: some experiments have shown a benefit from increased CS/C but others have not. This outcome may depend on the plane of nutrition after calving. CS/C values > 3.25 have led to small decreases in MY. During lactation, CS responds to change in plane of nutrition in parallel with MY, milk protein content, and live weight. Some but not all the available evidence indicates that the fall in CS in early lactation may be limited physiologically, and subsequent recovery of body reserves may be characterized by a compensatory partition of nutrients to body as well as a response to increased plane of nutrition relative to requirements for milk production. Further investigation is required regarding application of CS to mid to late lactation, particularly partition of nutrients between milk and body, to multiple lactations, to health and fertility, and to CS in relation to the cow potential.

Effect of amount and composition of feed given over three lactations on the performance of the dairy cow.

Eighty-nine autumn-calving first calf and adult Friesian cows participated in an experiment on the effect of feeding over three lactations on milk production and live weight change. Fixed daily allowances of digestible energy (DE) formed two of the treatments (h, H; moderate, M). Diets of similar composition were used for both treatments and rations were weighed daily for each cow. The cows within these treatments were re-randomized to H or M at second and again at third parturition on experiment. A further treatment (ALF), applied continuously over three lactations, consisted of the M allowance of compound feed, weighed daily for each cow, plus as lib. weighed, group-fed forages. The ALF animals were randomized for each lactation into two groups both of which received the same total compound feed allowance over the first 26 weeks of lactation. For one group (Flat) equal amounts were given daily whilst for the other group (Step) the daily amount was decreased monthly. After week 26 equal rations were fed. Hay, maize silage and grass silage formed the forages in winter. Grass, cut for the H and M groups but grazed for the ALF group, provided the summer forage. Energy intakes covered some 80-110% of requirements. Yields of milk and of milk solids responded similarly for both parties. In the first experimental lactation, treatment H led to greater yields compared with M. H also led to smaller losses of live weight in early lactation, equal gains in mid lactation, and smaller gains in late lactation and the dry period, compared with M. Extension of H into a second lactation increased the advantage in milk and solids yields observed in the first lactation on experiment. Recovery of body reserves on treatment M continued. Treatment H in a second lactation on experiment after M in the first lactation led to even greater compensatory gains in live weight at the expense of milk production. There was no effect in the third lactation of experiment of treatments applied in the first lactation. Treatments H and M applied factorially over lactations 2 and 3 gave the same pattern of treatment effects as in lactations 1 and 2. Treatment ALF broadly supported the same milk yield and live weight change as treatment H but improved fat, protein and lactose yields. Within treatment ALF, Flat and Step distribution of compound led to equal performance. Multiple lactation effects of ALF equalled those of H. The effects on milk composition of H compared with M treatment were variable. In general an advantage accrued to ALF over M but without long term effects.