This study looked at ewe effects on the number of lambs reared (litter size and mortality) and lamb 12 week weight (birth weight and growth rate). Over six years, data was collected on 5571 lambs born to around 3390 Romney (R), Finn cross Romney (F x R), East Friesian cross Romney (EF x R) and Poll Dorset cross Romney (PD x R) ewes. Ewe live weights were recorded pre-lambing and 12 weeks post-lambing. Lambs were weighed at birth and 12 weeks post-lambing. Ewe effects played a significant role in affecting the productivity of the system and many effects were cumulative. Over six years, the lambing percentage (lambs born/ewes lambing) was 165 %. Two tooth ewes had lower lambing percentages than the mixed age ewes (155 vs 170 %). Lambing percentages were 186 % for F x R, 171 % for the EF x R, 155 % for the PD x R and 153 % for the R ewes. Birth weights ranged from 1 kg to 9.8 kg, with a mean of 4.8 kg. Lambs born to F x R ewes (4.28 kg) were significantly lighter at birth than those born to PD x R ewes (5.34 kg). On average, 5 % of lambs were dead at tagging and 11 % of all lambs born were not present at 12 wks of age. The relationship between birth weight and mortality differed to previously published New Zealand reports with high survival rates in the present study over a wide range of birth weights from 3 to 9 kg. It is likely that changes in management practices (improved nutrition, heavier ewes, and selection for easy care lambing) may have contributed to the reduced mortality rates in the heavier lambs in the present study. Ewe genotype modified the effect of birth rank on birth weight and mortality. The average penalty for each additional lamb was smaller for the progeny of the EF x R and F x R ewes (0.85 and 0.88 kg, respectively) than for the progeny of the R and PD x R ewes (1.09 and 1.17 kg, respectively). Triplets born to R ewes had significantly lower survival rates than the other lambs. Heavier birth weights are likely to result in heavier lambs at 12 weeks of age that can be sold earlier. Keywords: birth rank, birth weight, ewe breed, lamb growth, lamb survival

No abstract

The production of resident pastures on rolling hill country was measured in three paddocks over 20 years at Poukawa in Central Hawke’s Bay. The pastures had been routinely fertilised with 250 kg/ha/yr of superphosphate but no pasture renovation, nor nitrogen fertiliser application, occurred during the measurement period. Total annual dry matter (DM) yield ranged from 4.5 to 12.8 t/ha/yr, which shows the level of variability to be expected in this summer-dry environment. The greatest proportion (60-90%) of growth occurred in winter/spring with consistent mean growth rates of 50-62 kg DM/ha/d in September and October. These rates were calculated to be 5.49±0.55 kg DM/ha/°Cd when spring moisture was non-limiting. The pastures had a mean water use efficiency of 16.9±0.34 kg DM/ha/mm of water available (R2 = 0.93). The amount of water available was calculated from a soil water budget based on a plant available water holding capacity of 124 mm (0-1.0 m depth). The results provide coefficients that can be combined with readily available climate data to predict pasture growth rates for feed budgeting purposes. Rainfall data collected on-site was highly correlated (r=0.94) with that predicted from the NIWA virtual climate station network.

No abstract

Yield and animal performance data from plantain/clover and resident ryegrass-based pastures were collected over several years from six properties on the East Coast of the North Island. This information was used in a FARMAX® model developed for a hypothetical farm based on data collected by the Beef + Lamb Economic Service. The hypothetical farm was 495 ha with 50 ha of flats used for silage and/or winter forage crop. The base model had a gross margin of $703/ha. The 50-ha flat block was modelled as if in a plantain rotation with two thirds in plantain and one third in annual ryegrass each year. The higher yields and better-quality feed on the plantain block improved animal performance and carcass weights. Early mating of one-year ewes for feeding on plantain provided a very high-returning enterprise. More ewes and lambs were killed early at heavier carcass weights with a premium before the onset of summer-dry conditions. This became a force multiplier across the entire farm as more feed was available for other stock and lamb carcass weights increased across the farm. Highest returns were generated by using the extra quality feed to increase ewe liveweights by 8 kg. Whilst ewe numbers had to be decreased, this was more than compensated for by the higher lambing percentage and greater number of lambs from mated hoggets. The combined effect was an increase in farm gross margin by around $200/ha and in farm returns of $100,000.

No abstract

This study aimed to examine the economic response to high rates of N in a winter lamb trading operation and was an "add on" to a commercial lamb trading operation in Hawkes Bay. The general policy of the lamb trading operation was to purchase store lambs in autumn at 35 kg liveweight, rotationally graze through winter and early spring and draft for slaughter at 45 kg liveweight. Keywords: nitrogen fertiliser, lamb performance, farmlet trials, lamb finishing, cost effectiveness