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The growth rate and carcase characteristics of Friesian bulls and steers were compared when the animals were fed solely on pasture from 8 to 18 months of age. The animals were set stocked at rates ranging from 3.0 to 6.0 animals ha-1, so that average growth rates of the steers ranged from 0.87 to 0.57 kg d-1. All were slaughtered at 18 months of age for the manufacturing meat trade. For each additional animal per hectare the average daily liveweight gain of both bulls and steers was reduced by 0.1 0 kg d-1. However, at all stocking rates bulls maintained a 0.06 kg d-1 advantage over the steers. These results do not support the suggestion that as the plane of nutrition increases, so does the advantage in growth rate of the bulls over that of the steers. Seasonal liveweight gains of the two sex types and the effect of stocking rate on these are discussed. For each 0.1 0 kg d-1 increase in steer liveweight gain carcase weight per animal increased by 19 kg and the bulls produced 25 kg more carcase weight than the steers. As the plane of nutrition increased, the percentage of saleable meat produced by the steers was constant (66.2%) while that of the bulls increased (68.7%-72.3%). This trend was reversed for the percentage of fat trimmed out of the carcases. The fat trim of the bulls was 3.6% while that of the steers increased from 6.4% to 8.9%. Over the entire range of nutrition levels, bulls were superior to steers in all attributes considered necessary for the manufacturing trade. However, under Australian conditions, seemingly unjustifiable penalty rates for slaughtering and, to a lesser extent, farmer prejudice, severely restrict the use of young grazing bulls for lean meat production.

The effect of time (morning or afternoon), intensity (three or four calves per cow), frequency Once or twice daily) and duration (1, 2, 4 or 8 weeks) of suckling on the performance of multiparous Friesian cows in early lactation was studied in four experiments. In each experiment there was a group of cows that were machine milked twice daily from calving. Milk production from sucked cows was greater during the suckling period than from machine-milked cows in the same period, but in no case was there any significant difference between suckling treatments. Increases in production during the 8-week suckling period ranged from 7.1 (P > 0.05) to 19.4% (P< 0.05), or from 75-21 8 kg. The extra milk produced by the cows sucked once daily went to the calves, and similar (P > 0.05) quantities or significantly less milk (P< 0.05) was produced at the alternate machine milkings compared with non-sucked cows in the same period. Regardless of suckling treatment in early lactation, the cows failed to show any carryover benefit. Lactation length and liveweight change in cows was unaffected by suckling treatment. The interval of post-partum anoestrus increased by about 6 days for each additional week of suckling. The average increase due to 8 weeks suckling in the four experiments ranged from 41-66 days. Teat damage increased with duration of twice-daily suckling, but had no effect on yields after sucking stopped. Teat damage of cows sucked once or twice daily to 8 weeks was similar. The incidence of mastitis was low in both sucked and machine-milked cows, and was not related to suckling treatment. Multiple sucking of Friesian cows in early lactation is a means of obtaining more milk from individual cows without incurring penalties in liveweight and body condition loss; it has no effect on post-weaning milk production.

Two management systems for dairy farms, early (silage farmlet) and late (hay farmlet) conservation, were compared for milk production in 4 consecutive years, at 2 cowsha. Half of the total silage farmlet area was made to wilted silage in each year. The remaining area was conserved as direct-cut silage in the first year and hay in the fourth year. About 40-50% of the hay farmlet area was made to hay. Over the 4 years, the silage farmlet produced an average of 8.2% more milk and 11.9% more (P<0.01) milk fat per year than the hay farmlet. The improvement in milk and milk fat production averaged 2.7 and 5% (P<0.01) in the spring and 27.4 and 30% (P<0.01) in the period from commencement of supplementary feeding in the summer. On average, the silage farmlet conserved a greater area, but because of high storage losses and greater consumption, it required more brought-in feed than the hay farmlet.

Growth rate and carcase characteristics were compared for Friesian bulls and steers fed solely on pasture and set stocked at 4.9 animals ha-1 Over a period of 11 3 weeks the animals achieved a mean liveweight gain of 0.5 kg animal-1 day-1. At this level of nutrition no significant difference in the growth rates of the bulls and steers was evident. However, the bulls had a higher dressing percentage (3.4 per cent), a higher percentage yield of meat (5.5 per cent), a lower percentage yield of trim (2.3 per cent), a lower percentage yield of bone (3.1 per cent), a larger eye muscle area (4.9 cm2), a greater carcase weight (1 7 kg), and a greater weight of saleable meat (24.1 kg). The steers had a higher percentage of total carcase in the hindquarter (3.6 per cent).

Liveweight and skeletal size at mating and first calving, and milk production in the first lactation of 193 heifers from 16 farms in West Gippsland, Vic., were compared with the productions of mature cows in each herd (mean mature cow production, 136-270 kg milkfat/cow). Mean minimum target liveweights ( s.e.) for successful conception were calculated to be 219 3 and 319 7 kg for Jerseys and Friesians, respectively. These weights were related by regression to skeletal sizes to aid in the management of feeding heifers. Within the range of heifer sizes considered in this study (mean liveweight [s.e.] after calving of 279 28 kg and 383 40 kg for Jerseys and Friesians, respectively), we conclude that, provided heifers are sufficiently grown to conceive, their milk production in first lactation will not be substantially affected by size at mating and calving.

Parturition was induced in one member from each of eight sets of monozygous twin dairy cows by intramuscular injection of 20 mg Dexamethasone trimethylacetate. The resulting gestation lengths were less (P < 0.01) than those of the untreated twin counterparts. The actual 'within' twin calving spread was reduced to nil to 32 days (mean S.D. 9 12 days) from an expected range of 22 to 53 days (mean S.D. 38 12 days). The drug had a variable latent period (time from injection to parturition) and had no apparent effect upon the ensuing lactation yield (P > 0.05) or the subsequent return to postpartum oestrus (P > 0.05). The induced calves had lighter birth weights (P <: 0.01) and a higher mortality (6/8) than calves-from untreated cows (no deaths). There was a significant (P < 0.01) positive correlation (r = 0.846) between gestation length and birth weight of the calf.