BULL BEEF PRODUCTION

The development of a 74 hectare bull beef productlon system is outlined. With pasture development regarded as a high priority techniques used to apply sufficient grazing pressure to change pasture composition are discussed. The combination of stock classes and pasture management changes has allowed a dramatic increase in the proportion of ryegrass and white clover in the sward. Currently a slightly modified one year bull beef system 1s being operated. Spring calves (140) are farmed through to 16-18 months of age and in addition autumn reared calves (60) are taken through to slaughter at 19-20 months. Performance and management objectives are given for this producton system and fhe key factors relating to their practical implementation are discussed.</jats:p

WINTER GRAZING MANAGEMENT SYSTEMS BASED ON INCORRECT PASTURE GROWTH RATES

Comparisons were made between three winter grazing management systems based on different pasture growth rate predictions. Management systems were chosen to restrict ewes to their budgeted intakes while at the same time reaching a target of 1500 kg DM/ha average pasture cover at lambing. Two of the three farmlets failed to meet their planned objectives. Changes in average pasture mver were frequently the result of an interaction between pasture growth rate and herbage intake. It was concluded that rotation length alone gave insufficient control over the management system and for a farmer to be able to make appropriate adjustments a minimum level of monitoring would be to estimate animal intake rate and average pasture cover.</jats:p

Can we reverse the process of deterioration in a run down prairie grass pasture?

An experiment was designed to determine whether aerating soil with a seed drill coulter, or improving soil fertility through nitrogen application, could reverse the deterioration of a 'Grasslands Matua' prairie grass pasture. A simple model outlining the changes in yield components characteristic of pasture deterioration is proposed, against which the effects of the treatments have been compared. The aeration treatment accelerated deterioration, probably because the technique caused plant damage and/or soil compaction. However, autumn nitrogen application was successful in reversing the early stages of pasture deterioration by improving plant size through increased tiller size. Keywords Matua prairie grass, Bromus willdenowii Kunth, soil aeration, nitrogen, model, yield components</jats:p

Efficiency of pasture and supplement management in high producing dairy herds

In 1998 a three-year dairy farm monitoring programme funded by AGMARDT (Agricultural Marketing and Research Development Trust) was established on twelve dairy farms in the southern North Island of New Zealand where policy had changed from a focus on high production per ha through high stocking rate to a management based on reduced stocking rate and strategic use of supplements to enhance both production per cow and per ha. The project involved a detailed three-year data collection which included measurements of the quantity and composition of pasture and supplements consumed as well as animal performance. Analysis of the results of the third year (2000/2001) on nine of these farms with complete data sets identified a range of metabolisable energy (ME) intake (50669 - 70135 MJ ME/cow/yr). Supplementary feed represented on average 24% (21 - 27 %) of the total intake of ME, the main supplements being pasture silage (summer to winter), turnips (summer) and maize silage (autumn and winter) consumed by lactating cows, and grazing off by dry stock. There was a range of milksolids (MS) production per cow (372 - 424 kg/year) and per hectare (921 - 1264 kg/year). The average economic farm surplus per hectare of NZ$3077 (NZ$2425 - NZ$3867) for the case-study farms was approximately 43% higher than the top 25% farms in the Manawatu region. Mean values of return on assets for the case-study farms (12.9%) and top 25% farms in Manawatu (13.0%) were similar. Good pasture management based on controlled preand post-grazing herbage mass targets (mean 2650 and 1900 kg DM/ha, respectively), strategic use of supplementary feed to control pasture deficits, and moderate stocking rates (overall mean 2.7 cows/ha), provided high allowances of high quality herbage (organic matter digestibility ranging from 742 to 845 g/kg DM) and maintained high levels of milk production (411 kg MS/cow and 1100kg MS/ha). The comparison with industry data showed that the casestudy farms were highly productive and profitable dairy systems, at least under the conditions of the 2000/2001 season. However, the result indicated the need to improve management skills to limit feed wastage under generous feeding management, and also the limitation of conventional procedures for monitoring pasture consumption in farming systems. Keywords: animal performance, dairy systems, energy intak e, herbage quality, pasture management, profitability</jats:p

Dairy systems study of the effects of contrasting spring grazing managements on pasture and animal production

This paper reports the results of a dairying systems study at No. 4 Dairy, Massey University, investigating whether the benefits of contrasting spring grazing managements previously measured in small-scale experiments could be measured within the management constraints of a selfcontained farm production system. Management contrasts were early control (EC), in which pastures were closely controlled throughout spring and summer, with average pasture cover kept at approximately 2000 kg DM/ha, and late control (LC), in which average pasture cover was increased to 2700 kg DM/ha, allowing some reproductive growth through October and November before returning average pasture cover to 2000 kg DM/ha in December. Average pasture cover and pre- and post-grazing cover differences between treatments were achieved over late spring in all three years. However, average pasture cover during summer did not differ between treatments. Milksolids (MS) production per cow during the spring phase was higher for the LC treatment than for EC, but the differences disappeared over the December control phase and overall differences were small and inconsistent. The use of mechanical topping in December 1995/96 reduced the penalty to LC MS production experienced in previous years. Late control spring grazing management did not significantly increase pasture or MS production within the confines of a closed production system, contrary to the results of previous small-plot and paddock-scale experiments. Keywords: dairy cow, dairy systems, Lolium perenne, milksolids production, pasture production, spring grazing management, Trifolium repens</jats:p

Estimation of dairy pastures - the need for standardisation

A study was undertaken to determine the reason for the differences in the estimation of pasture mass between dairying research centres in New Zealand and to define a common system of estimation that would overcome these differences and be able to describe the pasture situation on commercial dairy farms in different parts of New Zealand. Differences in the visual estimation of pasture between a standard observer and a local observer at the different dairying research centres in the order of 900 kg DM/ha were identified. This was attributed to a lack of regular visual calibration of persons who regularly assessed pasture, as differences between centres in the actual harvested DM yields of the visually assessed plots varied less (200-400 kg DM/ha). To achieve uniformity it is recommended that all centres measure total herbage mass (the amount of herbage above ground level) to regularly calibrate pasture assessment in dairy grazing management studies and on dairy farms. A reasonably consistent estimation of average farm cover, the ranking of paddocks (r2 &gt; 0.9) for the purposes of determining grazing order and the estimation of pre- and post-grazing herbage mass was achieved using the rising plate meter and L'Huillier &amp; Thomson's standard set of calibration equations published in 1988. With these recommendations, estimation of pasture will be more uniform. Standard calibration of the plate meter for the determination of rate of DM disappearance (pre-post grazing) achieved less consistency. Keywords: herbage mass, pasture assessment, pasture height, rising plate meter, visual pasture estimation</jats:p

Morphogenic and structural characteristics of guinea grass pastures submitted to three frequencies and two defoliation severities Características morfogênicas e estruturais de pastos de capim-tanzânia submetidos a três frequências e duas severidades de desfolhação

It was evaluated the morphogenic and structural characteristics of guinea grass under rotational at three grazing intervals and two defoliation intensities. Grazing intervals corresponded to the time needed by the forage canopy to reach 90, 95 or 100% of incident light interception during regrowth and they were evaluated combined to two defoliation severities (post-grazing conditions, 25 and 50 cm of height), being allocated to experimental units according to a complete randomized design, with three replicates and 3 × 2 factorial arrangement. The experiment was conducted from July 2003 to May 2004. For evaluation of morphogenetic and structural characteristics, ten tillers per experimental unit were selected. Morphogenetic and structural characteristics were strongly influenced by seasons of the year inasmuch as leaf elongation rate increased 3.5 fold from winter to summer. In addition to year season effect, there was also an effect of defoliation frequencies on tiller population density, which was greater in the defoliation period corresponding to 90% of light interception, especially if evaluated in relation to the interval corresponding to 100% of light interception. Defoliation frequency is determinant in expression of phenotypic plasticit, acting on the control of stem elongation.<br>Foram avaliadas as características morfogênicas e estruturais do capim-tanzânia sob lotação rotativa em três intervalos de pastejo e duas severidades de desfolhação. Os intervalos de pastejo corresponderam aos tempos necessários para que o dossel forrageiro atingisse 90, 95 ou 100% de interceptação da luz incidente, durante a rebrotação e foram avaliados em combinação a duas severidades de desfolhação (condições pós-pastejo, 25 e 50 cm de altura), sendo alocados às unidades experimentais segundo um delineamento de blocos completos casualizados, com três repetições e arranjo fatorial 3 × 2. O experimento foi realizado de julho de 2003 a maio de 2004. Para avaliação das características morfogênicas e estruturais, foram selecionados dez perfilhos por unidade experimental. As características morfogênicas e estruturais foram fortemente influenciadas pelas épocas do ano, uma vez que a taxa de alongamento de folhas aumentou 3,5 vezes do inverno para o verão. Além do efeito da época do ano, também houve efeito das frequências de desfolhação sobre a densidade populacional de perfilhos, que foi maior no intervalo de desfolhação correspondente a 90% da interceptação luminosa, principalmente se avaliado em relação ao intervalo correspondente a 100% da interceptação luminosa. A frequência de desfolhação é determinante na expressão da plasticidade fenotípica, principalmente por influenciar na densidade populacional de perfilhos, atuando no controle do alongamento dos colmos