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355. Calves can normally be weaned at 5 weeks of age, when they are eating at least 1kg of compound feed. They are usually housed in loose yards where good quality forage can be gradually introduced to the diet. Summer and early autumn calves should be housed during the winter in a well-ventilated and draught-free building. When weather conditions permit, calves should be turned out and should continue to receive compound feed which can be gradually withdrawn as grass becomes plentiful. On known mineral deficient soils, suitable mineral supplement should be available throughout the grazing season.
356. Heifers can remain outside as long as weather and ground conditions allow, provided they have access to adequate supplementary feed and some form of shelter. In many cases it is more convenient to house heifers in loose housing. If a cubicle system is in use, it is desirable to adapt it in order to train the heifers for future housing.
357. Heifers should be served at 15 months to calve at two years of age. Target weights vary depending on the breed. Achieving target weight at service and calving is vital for good welfare. Calving under 21 months and over 27 months is likely to produce more difficult calvings and higher calf mortality. It is important to feed adequately for four weeks before and four weeks after service to achieve a consistently high conception rate. Methods of improving oestrus detection and conception rates have been discussed in the section on fertility.
358. Young animals at grass are vulnerable to internal parasites. When clean pasture is not available, a worm control programme for intestinal and lungworms should be drawn up.
359. In late summer, pregnant heifers are particularly susceptible to summer mastitis and control measures suggested in this report should be implemented.
360. Major changes in housing or diet should be avoided, particularly around the service period.
361. Heifers should be suitably marked to allow easy identification and thus reduce handling stress.
362. Heifers should be introduced to the dairy herd with care, at least four weeks before calving, to allow time to become used to their new, unfamiliar surroundings. If space is limited, they should not be housed with older cows which will dominate their feeding and lying areas.
363. Before calving, heifers should be trained to the use of the milking parlour and, where applicable, cubicles.
364. Pregnant heifers should not be allowed to become excessively fat.
365. In the last two months of pregnancy, heifers should be observed carefully at least twice daily. They should be housed in clean, dry conditions, or run in a convenient, accessible field.