ALBERT

Description: SUMMARYTwo trials were conducted, using 18 and 30 castrated male calves respectively, to investigate the importance of milk in the diet of calves during the first 8 months of life and its effect on herbage intake and live-weight change. Reconstituted milk substitute was fed in a manner that simulated the supply of milk for lactation, yields of 2101, 1635 and 1165 kg (Expt 1) and 1906, 1609, 1304, 1005 and 701 kg (Expt 2) over a 240-day period. Calves were purchased in mid-February, when approximately 1 week old, and housed individually until turned out to graze at 10 weeks of age. At pasture, the calves were strip grazed on swards of Lolium perenne cv. S. 23 or S. 24 and given a daily herbage allowance of 60 g D.m./kg live weight.The live-weight gain response to milk consumption was 81 g/kg milk fed during the housed period and 50 g during the grazing season. Herbage and milk intake per unit live weight were inversely related but because the grazing season responses were confounded with the treatments during the housed periods, it was not possible to determine true replacement rates. Herbage intake per head increased with time but there was no general trend when intake was expressed per unit live weight.

Description: SUMMARYTwo trials were conducted to measure the herbage intake of South Devon cross calves suckling Hereford × Friesian cows and to test the validity of applying the relationships established between milk and herbage intake and milk intake and live-weight gain for artificially fed calves to suckled calves. In Expt 1 the milk and herbage intakes of eight calves were monitored. Their average milk consumption was 2250 kg and their growth rate was 1·14 kg/day. Both milk consumption and growth rate were higher than those recorded in other studies with artificially-reared calves. Nevertheless, it was possible to predict the herbage intake and growth rate of the calves from the relationship previously established for artificially reared calves. The nutrition of cows in Expt 2 was manipulated to induce changes in milk production and the consequent effect on the herbage intake of their calves assessed. Milk consumption was at a lower level and herbage intakes fell within the expected range. Herbage intake also responded to changes in the milk production of the cows. The observed herbage intakes and live-weight gains were similar to those predicted from previously established relationships with artificially fed calves.

Description: SUMMARYForty-eight Hereford × Friesian steer calves purchased at 7–10 days of age were reared on reconstituted milk substitute and groups of 12 were weaned at 86, 128, 170 or 212 days. Six calves at each weaning age were fed high (H) and low (L) quantities of milk normally associated with 240-day lactation yields of 2000 or 1000 kg. Calves were housed until day 63 of the experiment and then strip-grazed on swards of Loliun perenne with a daily allocation of herbage dry matter equivalent to 60 g/kg LW.Herbage intake per unit live weight prior to weaning was consistently greater for the calves receiving low quantities of milk. Following weaning there was a rapid rise in herbage intake towards a maximum of 30 g OM/kg LW when sward conditions were non-limiting. The amount of milk fed prior to weaning affected herbage intake after weaning, and H groups did not achieve similar intakes to their L contemporaries until some weeks after weaning. The H groups grew faster from birth to weaning than the L groups but they experienced a more severe check in live-weight gain after weaning which nullified the advantage of better weight gains between the start of the grazing period and weaning. In consequence, there was no significant effect of the quantity of milk consumed prior to weaning upon live-weight gain during the grazing season. The results indicate a marked benefit from distributing a given quantity of milk over a longer feeding period as similar growth rates occurred for the H86 v. L128, H128 v. L170 and H170 v. L212 groups. Calves receiving milk consumed less herbage and spent a smaller proportion of the day grazing than weaned contemporaries, which suggests that metabolic rather than physical or behavioural factors are likely to limit their intake.