New Zealand - part 2
|3. CLIMATE AND AGRO-ECOLOGICAL ZONES
Anticyclones approach from the west across the Tasman Sea and bring settled weather conditions to most of the country. Low pressure troughs (depressions) of varying strength are interspersed between the anticyclones and move up the country from the south. In winter months, these depressions can bring rain, sleet and snow. The majority of snow falls on the Southern Alps of the South Island and Central Plateau of the North Island but may occasionally fall to sea level in Southland, Otago and Canterbury.
The mountainous terrain has a strong influence on regional climates. There is a strong rainfall gradient from west to east, particularly in the South Island (Figure 7). This results from the rain shadow formed by the Southern Alps. Long-term mean annual (1951-1980) rainfall ranges from 360 mm (Alexandra, SE South Island, 45.267°S, 169.383°E) to >6 700 mm at Milford Sound (SW South Island, 44.667°S, 167.917°E). The maximum recorded annual rainfall was 18 000 mm on the West Coast of the South Island (Crop River, Hokitika catchment). Annual rainfall is between 600–1 500 mm for most of the country but large areas of both islands receive >2 500 mm/yr. In most locations, long-term mean monthly rainfall may show slight seasonal variation which is insufficient to replenish the soil water used when potential evapotranspiration increases in summer months. This leads to the development of summer soil moisture deficits that restrict pasture growth. On the east coast of both the North and South Islands these deficits can develop between September and April before autumn rainfall alleviates water stress conditions.
The gradient in mean annual temperature runs north to south. Mean annual temperatures are 16-18°C in the northern North Island and 8-10°C in the south of the South Island. Mean annual temperatures also decrease by about 2°C for every 300 m increase in altitude. Mean annual sunshine hours (1971-2000) are between 900 and 2600 hours/yr. The lowest sunshine hours (900 to 1 400 hr/yr) occur in Fiordland and parts of the west coast of the South Island. The highest (2 200 to 2 600 hr/yr) occur in the northwest of the North Island and the top of the South Island.
This seasonal temperature variation affects the length of the growing season and consequently the potential production that can be achieved in specific regions. Table 4 shows the amount of thermal time accumulated above a base temperature of 0°C from long-term data at selected locations from 1 July to 30 June. Of these, the longest growing season occurs in Kaitaia (5 730°Cd) and the shortest growing season is at Invercargill which is 40% lower (3 563°Cd) but the growth season here is severely restricted by killing frosts.
Rainfall is also influenced by seasonal variations in the strength of the westerly winds. Spring rainfall is increased west of, and in, the mountain ranges as the westerlies rise to their maximum strength in October. Consequently, there is an unavoidable but complementary decrease of rainfall in the lee of the ranges. Long-term records mask this annual variation. For example, at Lincoln, Canterbury, the long-term (1975-2007) mean annual rainfall is 627 mm/yr but has ranged from a minimum of 308 mm (1988) to a maximum of 1 015 mm in 1978. Average monthly rainfall indicates a reasonably even distribution of ~50 mm/month throughout the year with slightly more rainfall in winter months. However, Figure 10 shows that in July (winter), which has a long-term mean monthly rainfall of 63 mm, the minimum rainfall was 11 mm (2000) and the maximum was 161 mm (1977). In December (summer), with a long-term mean monthly rainfall of 54 mm, the minimum was 1 mm (2003) and the maximum was 157 (1978). Thus, rain tends to fall in large (30-130 mm) events at infrequent intervals throughout any given year.
Potential evapotranspiration and potential soil moisture deficits
A potential soil moisture deficit (PSMD) can be calculated as the difference between PET and rainfall in a July-June growing season. When potential soil moisture deficits exceed 100 mm pasture production is compromised and significant losses occur when deficits exceed 150 mm (McAneney
et al., 1982). In eastern
Figure 13a shows the extent of the potential soil moisture deficit,
based on potential evapotranspiration (PET) for dryland areas (no irrigation)
on the 31 December (mid summer) across
Frost and snow events
O’Connor (1993) summarised the main activities and identified
14 distinct landscape areas for
Within pastoral systems, about 55% of improved pastures are flat to
rolling (slope 0-15°). A further 13% are hill country (16-20°
slope) while the remaining area is classified as steep hill or high
country (>21° slope) (Hodgson et al., 2005). There are
nine broad farm classes used to classify ruminant livestock production
Arable and horticultural production
Over the last decade, greater diversification of land use has been evident, especially for horticultural land. As an example, the area of land in vineyards increased by 28% from 1997 to 2002 with large areas converted in Gisborne and Marlborough (Figure 16) with additional expansion into parts of Canterbury and Otago. Table 8 shows the area harvested (ha) for the year ending 30/6/2007 of selected outdoor vegetable, fruit, major cereals and herbage seeds (Department of Statistics, 2007).
4. RUMINANT LIVESTOCK PRODUCTION SYSTEMS
Ruminant livestock systems in
Table 10 compares the environmental and farm structure differences in the eight farm classes used by Meat & Wool New Zealand Ltd (Matthews et al., 1999; Hodgson et al., 2005) plus a ninth class to describe dairy farms. Descriptions of each farm class follow.
South Island high country
Steep hill and mountainous terrain combined with a short growing season means annual pasture production is low and intensification may not be economically viable. Pasture production on high country varies depending on position in the landscape and level of pasture improvement. For example, in a 600-900 mm/yr rainfall environment production from unimproved pastures ranges from 0.3-1.0 t DM/ha/yr; improved pastures on shady faces can yield 2.5-5.5 t DM/ha/yr; on sunny faces improved pastures can produce 2.0-5.0 t DM/ha/yr. Improved pastures on flat land (terraces and valley bottoms) can yield between 4.0-10.0 t DM/ha/yr (Matthews et al., 1999). Farms are stocked with a combination of merino sheep, beef cattle and deer, all of which are seasonally set stocked. Ratios between stock classes are altered depending on the season and commodity prices.
Historically, the main source of revenue has been wool (60-70% of farm income) but recent low wool prices have resulted in a shift to store lamb and calf production to increase farm income. Currently farm incomes are 51% from wool, 21% from lamb and 15% from beef (Figure 19) with a gross farm income of NZ$ 59/ha. Some farms have also run deer to sell weaners for finishing (venison) and for immature antlers (velvet) from a stag herd.
Appropriate stock management in winter and spring is essential in these systems due to the short growing season and harsh environmental conditions for production. Frost can occur throughout the year and snow may lie at altitudes above 1 000 m for several months. Within a grazing area, pasture production is highly variable because of variations in slope, aspect and altitude. In winter months animals grazing at high altitude may be lost due to snow if appropriate measures are not taken to protect vulnerable stock. Long (4-5 month), cold winters mean the active growing season is short. Therefore, these properties are highly reliant on forage crops (e.g. swedes, Brassica napus) and conserved feed from lucerne (alfalfa; Medicago sativa) or pasture based hay or silage, which is generally grown in spring on the limited flat land available in river valleys and old river terraces. These flatter areas are well subdivided and break fenced for feeding out during critical periods when feed demand exceeds supply.
Previously, about 80% of land grazed by high country farms was under pastoral lease from the Crown (i.e. owned by the government). These properties have been the subject of recent “Tenure Review” (see below). The process negotiates for landscapes of value to the nation. Large areas of higher altitude tussock grasslands have been returned to government management (Department of Conservation) and withdrawn from grazing. In the current review cycle higher value is placed on the lower altitude landscapes within this property class. In return, lease holding farmers are able to freehold lower altitude land which is less vulnerable to erosion.
Rangeland on these properties is dominated by native tussock species. These include: Chionocloa spp. (tall tussock or snow grass), Festuca novae-zelandiae (fescue or hard tussock) and Poa cita (silver tussock) interspersed with introduced low yielding but persistent browntop (Agrostis capillaris). Invasion by Hieracium species over the last 50 years has reduced the productivity of unimproved tussock grasslands. The most prostrate of these perennial daisies, Hieracium pilosella, has the greatest effect on productivity. Introduced woody weeds, gorse (Ulex europaeus), broom (Cytisus scoparius), sweet brier (Rosa rubiginosa) and conifers (wilding Pinus spp. from exotic forestry plantations) are also difficult to control under these extensive grazing systems.
South Island hill country
Properties within this land class (Figure 20) produce wool and breed lambs and cattle which are then sold to lowland intensive finishing properties (Farm Class 6). Mid micron sheep (merino x coarse wool cross breeds or Corriedale) are the dominant breeds and they graze modified tussock grasslands. Typically, about 75% of the stock wintered are sheep and 25% are beef cattle at about 4 s.u./ha. These properties are being forced to intensify as dairy conversions displace the intensive sheep and beef finishing properties on the more fertile lowland plains. The gross revenue for farms in this class in 2007/08 was NZ$ 211/ha and contributions from different sources are shown in Figure 21.
Low input pastures are a mix of low fertility tolerant and lower yielding pasture species which include Notodanthonia spp., browntop, sweet vernal (Anthoxathum odoratum), silver tussock, Yorkshire fog (Holcus lanatus), adventive annual legumes such as suckling (Trifolium dubium) and haresfoot (T. arvense) clovers. Development of improved pastures, which includes grass/legume pastures, areas of lucerne for hay and brassicas for winter feed, depends on the level of investment for improvements. Soils tend to be naturally acidic (pH 4.5-5.5) and fertility can be improved by the application of lime and superphosphate fertilizers on river flats, terraces and easier lower slopes. Improved pasture species include perennial ryegrass, cocksfoot (Dactylis glomerata) white and subterranean (T. subterraneum) clovers. Supplements (predominantly brassicas) are grown on cultivatable land to provide winter feed. Clovers can be introduced to hill slopes by aerial broadcasting of inoculated seed followed by heavy stocking with sheep and cattle to trample in the seed.
North Island hard hill country
Annual rainfall for farms in this class is usually >800 mm and temperatures allow year round pasture production although lower rates occur in winter months. Steep hills are prone to soil erosion by mass movement following high intensity, saturating rain events and this is compounded when pastures are overgrazed.
Pasture yields are 2.0-6.0 t DM/ha/yr and properties are stocked at about 8-9 s.u./ha with dual purpose sheep breeds and beef cattle (about 60:40 sheep:beef s.u.). The majority of farm income is from the sale of store lambs, wool, cast-for-age ewes and beef weaners (Matthews et al., 1999; Hodgson et al., 2005). In the 2007/08 season, 63% of total gross farm income (NZ$ 351/ha) was from wool and sheep with a further 31% from cattle (Figure 23).
Low fertility, low producing species which include browntop, Yorkshire fog, sweet vernal, crested dogstail (Cynosurus cristatus), white clover and adventive annual legumes dominate pasture production. Significant fertility transfer of nitrogen, phosphorus and sulphur (Gillingham and During, 1973; Saggar et al., 1990) can occur on a micro-scale from slopes to sheep tracks and camps (section 5) where perennial ryegrass and white clover can dominate.
North Island hill country
Lower slopes and flat land are easily cultivated to introduce improved pasture species (Figure 24). Predominantly these are perennial ryegrass and white clover but subterranean clover and cocksfoot use is also widespread. In stock camps high fertility weed species dominate. These include Californian (Cirsium arvense), scotch (C. vulgare) and nodding (Carduus nutans) thistles, barley grass (Hordeum murinum) and nettle (Urtica urens). Nitrogen deficiency often compromises potential pasture production and this is addressed by management to encourage pasture legumes and some use of inorganic N fertilizer when it is economic.
Annual pasture production is 5.0-8.0 t DM/ha/yr (Matthews et al., 1999) from improved species and stocking rates can be 10+ s.u./ha. A high proportion of stock are sold in forward store or prime condition. Income from cattle accounted for 38% of total gross farm income (NZ$ 550/ha) in 2007/08 and a further 41% was from sheep production (Figure 25).
North Island intensive finishing systems
Stocking rates may reach 12-13 s.u./ha with the majority sold in prime condition to the freezing works. In favourable environmental conditions pasture production allows purchase and finishing of replacement ewes and store lambs obtained from surrounding hill country farms (Farm Classes 3 and 4). Income is from a combination of beef (including bull beef from the dairy industry) and prime lamb production. Gross revenue was NZ$ 799/ha in 2007/08. Providing grazing for dairy cattle and cash crops provided about 13% of gross farm income (Figure 27).
South Island finishing-breeding farms
Perennial ryegrass/white clover pastures dominate under irrigation while specialist forages such as lucerne and brassicas are sown to ensure the supply of high quality feed particularly on the dryland properties exposed to summer moisture limitations. Perennial ryegrass is generally infected with wild type or a novel endophyte to ensure pastures persist due to combined effects of pest load and periodic exposure to drought. Cocksfoot is more suited to these environments but yields can be below potential due to nitrogen deficiency, which can have a greater effect on total annual pasture production than the periodic summer drought (Mills et al., 2006). In dryland systems, where soil water stress compromises pasture production, white clover also fails after loss of the taproot 12-18 months after sowing. Weed species include browntop, twitch (Elymus repens), barley grass, vulpia (Vulpia spp.), dock (Rumex obtusifolius) and thistles. Pastures are renewed at 6-10 year intervals depending on the level of weed and pest infestation and the need for land to grow winter forage crops. Typically, about 10% of the property is renewed annually to maintain production of high quality forage and ensure winter feed supply. Lucerne can represent 30-40% of the effective farm area and cultivars need to be resistant to blue green aphid (Acyrthosiphon kondoi) and resistant/tolerant of stem nematode (Ditylenchus dipsaci) to ensure production and persistence. Lucerne stands are rotationally grazed to ensure optimum animal performance and stand persistence, and may be conserved as hay or silage.
Perennial ryegrass based pasture yields are generally 7.0-10.0 t DM/ha/yr in the Canterbury and Otago regions. This increases in years with above average summer rainfall. This allows stocking rates on dryland properties to be maintained at 9-10 s.u./ha and replacements are generally bred on-farm. Irrigated pastures may produce 15.0 t DM/ha/yr and carry up to 20 s.u./ha.
Of the NZ$ 670/ha gross income almost half (Figure 28) is generated from sheep production and income may be supplemented by using a limited farm area for vegetable or arable cash crops sown for either processing or seed production. Conversion of suitable sheep and beef farms to dairying occurs when irrigation is available and commodity prices provide a financial incentive.
South Island intensive finishing farms
South Island mixed cropping and finishing farms
About 70% of gross farm income is derived from grain and small seed production. Revenue sources and contributions to farm income per hectare for 2007/08 (NZ$ 2 348/ha) are shown in Figure 34. The remainder is split between stock finishing and process crops. In these systems specialist finishing pastures of lucerne or red clover, chicory and annual (Lolium multiflorum) or hybrid ryegrass may be used to maximise animal liveweight gains. Permanent pastures are uncommon because the pasture phase is part of the cropping rotation used to increase soil organic matter levels and restore soil structure.
Dairy systems are high input, and high fertility farms which are intensively managed. Perennial ryegrass pastures dominate with some white clover. Supplementary feed is required (pasture and maize (Zea mays) silage, palm kernel, brassicas) for winter months to complement perennial ryegrass pasture production curves. In the North Island turnips (Brassica rapa) and maize (for silage) dominate supplementary feed which may also be used to supplement pasture in summer. In the South Island, kale (B. oleracea spp. acephala) is the dominant forage crop for winter grazing. Dry stock are often wintered on other properties (e.g. mixed cropping properties described in Farm Classes 6 and 8) off the “milking platform”, particularly in the South Island.
Ruminant sector demographics, products and exports
The sheep industry
Total sheep numbers (Figure 36) have decreased from 70.3 million in 1982 to ~50 million in 1994 (MAF, 2009) and declined further to an estimated 34 million in 2008 (Department of Statistics, 2009b). This decrease represents the dynamic nature of the livestock industry which has responded to low sheep meat prices and an east coast drought. The drought reduced the national lambing percentage by 5.3% to 113% because ewes were in a poorer condition than usual at mating. Changes in land use included conversion of sheep farms to dairying, viticulture and cropping which offered higher returns than meat. Breeding ewe numbers decreased almost 10% in 2008, and the greatest reduction (almost 15%) was in Marlborough/Canterbury (Meat & Wool New Zealand Economic Service, 2009a). Dairy conversions occurred on 330 sheep and beef properties in 2008 which displaced 1.3 M sheep and beef stock units. Total conversions in 2008 were second only to the 360 properties converted in 1996/97. In contrast, only 70 farms underwent dairy conversion in 2007.
Despite the >30% decline in sheep numbers since 1990 (MAF, 2009), total national lamb meat production has increased by 12% over the same period. This reflects improvements in on-farm management practices, genetic gains for animals, higher quality pastures, animal and pasture based research and uptake of new knowledge by pastoral farmers.
In June 2000 it was estimated that 58% of all sheep were the dual purpose Romney. This was the dominant breed in the North Island and south of the South Island. In Canterbury, Marlborough and Otago the main breeds were Corriedale and Half breed dual purpose sheep which accounted for 6% and 4% of the national flock. South Island high country properties favour merinos (7% of all sheep) for their fine wool production. The other two major breeds are the Coopworth and Perendale which accounted for 10% and 7% of the national flock. The remaining 8% consists of crossbreeds, composites, Texel, Suffolk, Borderdale, Dorper, Poll Dorset and others. As producers move towards dual purpose flocks, genetics from Texel, Finn and East Friesian are being used to increase fertility and the meat production potential of the existing Romney, Perendale and Coopworth based flocks.
Half of New Zealand lamb exports in 2007/08 (volume) and 64% of lamb export receipts (value) were to the European Union. Of this, 30% was chilled lamb and 70% frozen. For the 2007/08 year (Sept) lamb exports accounted for NZ$ 2.52 billion (Meat & Wool New Zealand Economic Service, 2009a).
The Beef Industry
In June 2008, total beef cattle numbers were 4.3 M which was a 3.2% decrease from June 2007 (Figure 38) and 31% of these were breeding cows and heifers. Over 2.0 M head are slaughtered annually with 200 000 t of beef and veal meat exported to North America (54% of total beef exports) and 100 000 t to North Asia (28%). At 30 June 2008, the main beef breeds were Angus (~20%), Friesian (~23%), Angus/Hereford (8%) and Hereford (~8%) and mixed breed (32%).
About 70-80% of all beef cattle are farmed in the North Island (Farm Classes 3, 4 and 5). In Taranaki/Manawatu the 5.6% decrease in beef cattle numbers between 2007 and 2008 was a result of drought and dairy conversion whereas beef cattle numbers on the east coast of the North Island increased 5.3%. In the South Island, dairy conversion of finishing properties in Southland and Canterbury resulted in a 1.2 M head reduction between 2007 and 2008. This decreased weaner cattle numbers by almost 30% in Southland. However, breeding cow numbers increased 6-8% in Southland and Otago. The majority of the increase in breeding cow numbers occurred on Farm Class 2 (South Island Hill Country) properties in Otago, Farm Class 6 (South Island Finishing-Breeding) in Southland and retention of weaners on Farm Class 1 (South Island High Country) land in Marlborough/Canterbury regions.
The Deer industry
The NZ Deer Industry Industry was developed from aerial capture of wild red deer from the South Island high country. Deer were initially released in the Southern Alps and foothills of the Canterbury Plains in the mid 1800s for sport. Lack of predation and a suitable environment resulted in significant increases in the feral population. These animals are considered pests that destroy native vegetation. Aerial eradication programmes were used to control numbers in the wild and export of feral venison began in the 1960s.
In the 1970s live capture of feral red deer was initiated and these bloodlines form the basis of the deer industry. Red deer account for over 85% of the national herd with the remainder from Wapiti (Elk; Cervus canadensis) and red deer/wapiti crosses. A small number of fallow deer (Dama dama) are also commercially farmed. Genetic improvements have been made through the import of genetic material from Eastern Europe, the UK and North America.
The total number of farmed deer decreased 28% between 2005 and 2008 to 1.2 M (Figure 39) in response to product prices. About 70% of farmed deer are in the South Island (Department of Statistics, 2009b). In 2002, the total export value of the deer industry was NZ$ 375 M.
Deer farming occurs in a range of farming systems from small herds on lifestyle blocks (10-20 ha) to large herds grazing on extensively managed high country farms (Farm Class 1). In these larger farming systems deer are usually part of a diversified stock portfolio which includes sheep and beef cattle (Deer Industry New Zealand, 2009). Farming systems may focus on 1) breeding, 2) venison finishing or 3) velvet production, but commonly farms run a combination of operations to spread the economic risk. In 2002/03, deer contributed >50% of farm revenue on 2 300 farms nationwide and these farms accounted for 63% of the farmed deer population (Ministry of Agriculture and Fisheries, 2009b).
The red deer gestation period is ~233 days with fawning in November/December. This timing does not match traditional ryegrass/white clover pasture production curves which peak a month earlier in most dryland systems. Feed demand by this class of stock is also highly seasonal. Consequently, the majority of farmed deer sold for venison are slaughtered at 12-15 months of age by which time they have achieved 50-60 kg carcass weight. Target liveweights for commercially farmed stags and hinds of different breeds are presented in Table 11 . Velvet production ranges from 1 kg/head from young animals (2 years age), 2.5 kg/head from stags aged 5-8 years) with a 4.5 kg/hd maximum (Hodgson et al., 2005).
Most herds graze perennial ryegrass based pastures but specialist pastures of herbs and legumes such as chicory, red clover and lucerne are used to promote high liveweight production. During periods of feed deficit hay, silage and grain may be fed out to maintain feed supply.
The Dairy industry
New Zealand dairy systems are based on year round outdoor pastoral grazing. Direct grazing contributes about 90% of the animal feed demand and means production costs are low by international standards (Hodgson et al., 2005). When pasture production is insufficient to meet stock demand, due to low winter temperatures, or summer drought conditions, or when pasture quality is insufficient to meet the animals’ energy requirements, supplements such as hay, silage, concentrates and/or forages fed in situ are included. The primary pasture is perennial ryegrass/white clover which is high producing in environments with adequate rainfall (annual and seasonal) or where there is access to irrigation. Dairy systems are intensively managed with rotational grazing, twice a day shifts (which are often back fenced) which coincide with milking. Recently some farmers have begun ‘once a day’ milking programs.
Farms are generally run as either 1) owner operated 2) contract milk or 3) share-milking farm structures. Owner operators account for 63% of the national herd (DairyNZ and LIC, 2009). The majority of owner operator and contract milk structures dominate with smaller herd sizes (<200 cows). Almost 80% are based in the North Island. Share-milking is a farm structure in which there is a partnership between a farmer (landowner) and a share-milker (herd owner). Partnerships vary depending on the resources contributed by each of the partners. The 50/50 share milking structure accounts for a further 22% of the national herd while 10% are managed under a <20-29% share-milking structure and <2% are >54% share-milkers. Share-milking is the dominant farm operating structure when herd size is 200-449 cows and reflects the inputs necessary to manage larger herds.
The national dairy herd is >4 M milking cows/heifers and has increased by more than 50% since 1992/93. During this time the average herd size has increased from 180 cows/herd to 351 cows/herd while the number of herds has declined by 20% to 11 436 (DairyNZ and LIC, 2009). The average on-farm stocking rate has increased from 2.5 to 2.8 cows/ha and varies regionally from 2.2 cows/ha in Northland to 3.3 cows/ha in North Canterbury.
Herd sizes varied in 2007/08, with ~3% having <100 cows and ~3% having >1000 cows. About 52% of all national herds have 150-349 cows. The majority of dairy farms (79%) are located in the North Island of which 32% are in the South Auckland/Waikato region and 16% in Taranaki. Farm sizes in the South Island (526 cows/herd and 186 effective ha) are larger than those in the North Island (305 cows/herd and 110 effective ha) with the largest average herd size in Canterbury (>700 cows/herd).
Increased production by the New Zealand dairy industry is a reflection of improvements in on-farm management and genetic gain. Over 70% of the national herd undergo herd testing which allows low producing or disease prone (predominantly mastitis) animals to be identified and culled. The best performing stock are then used for breeding. Since 1998/99 the total amount of milk processed from the national herd has increased 40% from 10.6 billion l/yr to 14.7 billion l/yr. Milk solids (MS) production has increased by ~3.9 kg MS/cow/yr from 653 (1992/93) to 934 kg MS/cow/yr in 2006/07. Figure 40 shows the changes in annual milk solids production in New Zealand between 1992/93 and 2008/08 on a per cow and per hectare basis.
Main breeds and production differences. In all regions except Taranaki, Holstein-Friesian is the dominant breed and accounts for almost 45% of the national herd. Holstein-Friesian/Jersey crossbreeds account for ~33% (DairyNZ and LIC, 2009). Other breeds include Jersey (14%), Ayrshire (<1%) and “Other” (7%). The Holstein-Friesian dominates because of its higher average milk production (4 043 l milk/cow/yr) which is 12-43% more than the other breeds and consequently gives higher levels of protein (144 kg/cow/yr) and milk solids (318 kg/cow/yr). The average cow is in milk for ~250 days with Holstein-Friesian/Jersey crossbreeds having the highest average milkfat production (176 kg/cow/yr) while Jersey cows have the highest average milk solids (9.75%) and protein (4.03%) content.
Average cow liveweights differ with age and breed with 2 yr old cows having an average weight of 322-405 kg/cow. Across the three main breeds and all age groups (2->10 years) average liveweights range from 385 kg (Jersey) to 487 kg (Holstein-Friesian).
Since 1999/00, over 75% of the national herd has been mated using artificial insemination (AI). Successful AI requires on average 1.25-1.35 inseminations/cow. Bulls may be put out with the herd post AI with 1 bull/75 cows for a period of 4-5 weeks. To maintain a 365 d cycle all cows must be mated about 80 d after calving with a target body score condition of 5.0. The start of calving varies regionally due to environmental conditions. In Northland the start of calving is in mid July compared with early August in the South Island.
Animal health and welfare
Prevention is more desirable than control. For example, introducing new feed sources slowly allows the rumen to adapt and can reduce the risk of acidosis, bloat, diarrhoea and photosensitivity (Fleming, 2003). Shearing sheep to remove dags (wool contaminated with faeces) reduces potential for fly-strike. Culling of poor performing or susceptible stock is common practice to ensure the genetic structure of the herd/flock is suited to the system and environment.
Fortunately New Zealand’s isolation, border inspection and quarantine measures have ensured that economy crippling diseases such as Bovine Spongiform Encephalopathy (BSE) and foot and mouth disease (FMD) are not present. The Ministry for Agriculture and Fisheries (MAF) has protocols in place to allow rapid containment of any potential outbreak. Hydatids eradication programs have been highly successful and an eradication program for sheep measles which involves dosing working dogs and preventing access to raw sheep meat is in progress.
External parasites are treated with organo-phosphate dips or synthetic pyrethroids and insect growth regulators. Wool withholding periods following treatment range from 60 d for coarse wool breeds to 180 d for fine wool breeds. Prevalence of fly-strike has increased since the Australian green blowfly (Lucilia cuprina) arrived in New Zealand in 1982 but Lucilia sericata, Calliphora stygia and Chrysomya rufifacies also commonly initiate fly-strike. Ensuring diets have adequate fibre (reduced diarrhoea), and removal of faeces contaminated wool (shearing –crutching) are critical to reducing risk of fly strike. Animals which do become fly-blown require immediate treatment and this is highly successful when affected stock are identified early.
Although the fungus is found in grazed pastures worldwide the most severe problems occur in New Zealand. Exposed skin of infected animals develop weeping dermatitis and scabby skin and these areas can become infected or fly-blown. Furthermore, infected animals can have reduced fertility levels and reduced immunity levels to other diseases. A range of fungicide sprays can be applied to pastures but for control they must be applied before spore numbers increase. When spore numbers reach >200 000/g fungicides are unable to reduce them to safe levels so the risk of infection remains high.
Breeding programs which use disease resistant genetics is a major management tool to reduce prevalence of this disease. Use of rams tolerant to FE will not result in 100% of progeny showing tolerance but fewer progeny will be susceptible which will reduce incidence within the flock. Rams are tested using the Ramguard FE tolerance testing Service. Other management tools to control the disease infected animals include treatment with zinc salts which can help protect susceptible animals as the zinc binds with the toxin which can then not damage the liver or bile ducts. Controlled release zinc treatments are more expensive but offer protection for up to six weeks compared with drenches which do not offer protection for as long. Zinc can also be applied to pasture prior to grazing. Alternative pastures which have high legume content, tall fescue and/or chicory are recommended for grazing during periods of high risk. Forage crops are also a safe option. Spore levels are highest in regrowth from urine patches (more litter and a higher N content).
Dairy herd diseases
Two herds tested positive for EBL in the 2007/08 season and were culled while another two herds were treated (DairyNZ and LIC, 2009). Incidence of EBL is considered low by international standards. Nationally, herd incidence of EBL was <0.17% and no detections occurred in the North Island. For Tb testing, the prevalence of host species which include possums and ferrets determines the vector status of an area. Legally, all movement of cattle must be documented in case of an outbreak. Almost 3.1 M dairy cows were tested in 2007/08 of which 402 tested positive. Most animals (299) were identified in the South Island and 82% of these were found in areas with a known risk. The industry as a whole is proactive in monitoring, treating and preventing the infection and spread of disease.
Socio-economic limitations of pastoral agriculture
Currently legislation to control pastoral use of land relates to limitations being applied to some high altitude (above 900 m) tussock grasslands and to the extremely erosion prone soils in some steep hill country where tree planting is encouraged.
Land tenure of pastoral farms is mainly freehold. There are however some large areas of Maori land in the North Island which are farmed successfully as incorporations on behalf of iwi (tribal groups). Much of the South Island high country is Crown (Government) owned land which is leased for grazing to individual pastoralists. Some of those leases are currently being renegotiated. There are no communal pastures as flocks or herds are owned by individual farmers or commercial companies. These privately owned livestock do not graze any pasture or natural rangeland in common with domesticated livestock owned by other farmers.
The land tenure systems and lack of communal grazing mean that the New Zealand pastoral landscape is characterised by post and wire fences to maintain individual farm boundaries to avoid mixing privately owned livestock. Subdivision fences within farms form separate paddocks (grazed fields) so that different classes of livestock (species, age, sex) on a farm may be grazed separately. This provides a high degree of farmer control on when and where animals graze. The specific grazing management requirements of pasture species (e.g. lucerne) are more easily achieved with this acceptance of the need for fenced paddocks.
Because most products from pastoral production are exported, market access is an issue of national importance. New Zealand strongly advocates international free trade and the removal of agricultural subsidies in developed countries. The New Zealand government does not subsidise farm production. This ensures that scarce resources of land, capital and labour are used efficiently. This has led to New Zealand pastoral products being able to compete on world markets. However, the profitability of the New Zealand pastoral exports is vulnerable to exchange rate fluctuations and the use of rural subsidies by its trading partners.
More recently (2008/09) the extreme distance of New Zealand from its main markets has resulted in its pastoral products being challenged on the basis of their total energy content when delivered to northern hemisphere consumers. The suggestion that the concept of food miles should disqualify New Zealand pastoral products in environmentally sensitive western markets was shown to be false when the energy cost of livestock production in New Zealand plus its transportation was compared with competing subsidised UK and European local meat and dairy products (Saunders et al., 2006). New Zealand lamb was produced four times more efficiently and milk solids production efficiency was double compared with UK lamb and milk solids production. The greater use of N fertilizers, grain feeding and the need to house animals in winter in northern hemisphere production systems results in higher energy costs of production than the imported New Zealand livestock products. The low energy cost of production of the NZ products are related to the high reliance on N fixation by pasture legumes, relatively low use of N fertilizers, little grain feeding and the fact that grazing livestock are outside all year without winter housing. These production efficiencies allow New Zealand pastoral products to have lower total energy cost even when the cost of delivery to export markets is included.
New Zealand has a declining area in pastoral production. With marginal land being excluded from grazing and the encroachment of urban development the only way to increase pastoral production will be through intensification.
Crown pastoral land act 1998
The resource management act (RMA) 1991
The Act is intended to provide sustainable management plans which will protect the environment for future generations. The RMA states that every New Zealander, resource user and developer has obligations/responsibility to prevent, remedy or mitigate the effects of their actions on the environment.