1981). The management of calves on an early-weaning system: the relationship of voluntary water intake to dry feed intake and liveweight gain to 5 weeks. ABSTRACTA trial compared the voluntary water intake of 72 purchased British Friesian bull calves fed at different nutrient intake levels by varying the type and strength of the milk replacer given to 5 weeks of age. There was no control group without water on offer. Water was offered from the 1st day the animals entered the unit. All calves received 4 I/day of either cows' milk (12 calves), milk replacer with 100 g fat per kg (24 calves), milk replacer with 170 g fat per kg (24 calves) or milk replacer with 200 g fat per kg (12 calves). Standard early-weaning pellets containing 190 g crude protein per kg and hay ad libitum were on offer from the 2nd day on the unit. Results indicated that voluntary intakes of water were highest with calves fed on cows' milk and lowest on the milk replacer with 100 g fat per kg given at the lowest mixing strength, although differences were only significant in week 5 (P<005). By covariance analysis, the effects of water intakes on live-weight gain and on pellet intake were examined. The regression coefficient of live-weight gain (weeks 0 to 5) (kg) on water intake (weeks 1 to 5) (1) was b = 0-056 (s.e. 0021, P < 0 0 1 ) . The regression coefficient of pellet intake (weeks 0 to 5) (kg) on water consumption was: b = 0-082 (s.e. 0031, P < 0 0 1 ) . There was thus a significant correlation of both live-weight gain and pellet intake with water intake. For each extra litre of water consumed per day, there was an extra pellet intake of 0082 kg and an increase in live-weight gain of 0056 kg. There was a significant difference in total water intake according to the initial live weight of the calf.

Results are presented from six trials dealing with aspects of management on the cold ad libitum system of calf rearing using an acidified milk replacer containing over 600 g skim milk powder per kg.Thirty-six calves were housed in pens of six for each trial and were fed through a teat and pipeline from a storage barrel. Acidified milk replacer, pH 5·6, was mixed cold at 125 g/1 and made available ad libitum to 3 weeks. A rationed allowance was given daily, on a reducing scale, over the following 2 weeks with weaning completed at 35 days. A pelleted dry food containing 180 g crude protein per kg, together with water in buckets and barley straw in racks, was available ad libitum throughout. Each trial lasted 8 weeks. Results for the mean of the six cold ad libitum trials involving 216 calves were compared with the mean results of 10 conventional bucket-fed trials carried out separately at the same unit, involving 912 calves. All calves were purchased British Friesian male (bull) calves.Calves on the ad libitum system showed improved live-weight gains of 9·4 kg at 3 weeks, 8·8 kg at 5 weeks and 7·5 kg at 8 weeks, compared with the conventional system. The consumption of milk replacer powder was higher in ad libitum trials at 29·4 kg cf. 12·5 kg by bucket but intake of pelleted dry feed was lower on the ad libitum system at 50·7 kg cf. 71·3 kg to 8 weeks. Calf appearance scores were significantly improved on the ad libitum system which gave the main improvement in performance in the first 3 weeks.

Cassava is increasingly available in the United Kingdom for use in compound feeds. The trial reported here was a 2 × 4 factorial and compared dairy cow compound feeds containing nil or 400 g of cassava per kg, and crude protein levels of 100, 120, 140 and 160 g/kg, given in conjunction with grass silage.Forty-eight Friesian cows were used in a change-over design with four periods each of 4 weeks. The trial, therefore, compared six blocks of four cows on each of the non-cassava and cassava treatments, with each cow in a block receiving a different protein level. Compound feeds without cassava had a mean barley content of 600g/kg whereas feeds with cassava had a mean barley content of 103g/kg.There were no significant differences in milk yield (21 14 and 22·27 kg/day) or milk fat level (41·4 and 40·4g/kg milk) on the non-cassava and cassava treatments respectively (P ≤ 0·05). Differences in solids-not-fat concentration were also not significant.Average intakes of silage were similar on each type of diet. Daily intakes of the compound feed per cow varied from 6·95kg on the non-cassava treatment to 7·08kg on the cassava treatment. This difference in compound intake was not significant. The results indicated that compound feed containing 400 g of cassava per kg perform as well as cereal-based feeds and, therefore, cassava can be considered as a satisfactory replacement for cereals up to a level of 400 g/kg in compound feeds for dairy cows.

The response to avoparcin in cattle diets was examined in two trials. In trial 1 compound diets containing 0, 15, 30 or 60 mg/kg avoparcin were given to 32 British Friesian bulls from 231 kg body weight to slaughter at a mean body weight of 422 kg. In trial 2 diets containing 0, 15, 30 or 45 mg/kg avoparcin and composed of equal portions of dry matter (DM) from grass silage and compound food were given to 64 British Friesian steers over a 12-week period from 258 kg body weight to 340 kg body weight.There was a significant growth response of 120 g per head daily in trial 1 and 80 g per head daily in trial 2 to inclusion of 15 mg/kg avoparcin in the diet compared to the control diet without avoparcin. Food conversion efficiency of diets with 15 mg/kg avoparcin was improved by a reduction of 0·52 and 0·61 kg DM per kg live-weight gain respectively in the two trials. There was no further growth response or improvement in food conversion with higher levels of avoparcin with the diets used, the type of cattle employed and the management which applied in these trials. These findings are in good agreement with those previously published.

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