The effects of high stocking rates on milk production from dryland and irrigated Mediterranean pastures

2009 ◽  
Vol 49 (2) ◽  
pp. 100 ◽  
Author(s):  
S. Valentine ◽  
P. Lewis ◽  
R. T. Cowan ◽  
J. DeFaveri

An experiment using herds of ~20 cows (farmlets) assessed the effects of high stocking rates on production and profitability of feeding systems based on dryland and irrigated perennial ryegrass-based pastures in a Mediterranean environment in South Australia over 4 years. A target level of milk production of 7000 L/cow.year was set, based on predicted intakes of 2.7 t DM/cow.year as concentrates, pasture intakes from 1.5 to 2.7 t/cow.year and purchased fodder. In years 1 and 2, up to 1.5 t DM/cow.year of purchased fodder was used and in years 3 and 4 the amounts were increased if necessary to enable levels of milk production per cow to be maintained at target levels. Cows in dryland farmlets calved in March to May inclusive and were stocked at 2.5, 2.9, 3.3, 3.6 and 4.1 cows/ha, while those in irrigated farmlets calved in August to October inclusive and were stocked at 4.1, 5.2, 6.3 and 7.4 cows/ha. In the first 2 years, when inputs of purchased fodder were limited, milk production per cow was reduced with higher stocking rates (P < 0.01), but in years 3 and 4 there were no differences. Mean production was 7149 kg/cow.year in years 1 and 2, and 8162 kg/cow.year in years 3 and 4. Production per hectare was very closely related to stocking rate in all years (P < 0.01), increasing from 18 to 34 t milk/ha.year for dryland farmlets (1300 to 2200 kg milk solids/ha) and from 30 to 60 t milk/ha.year for irrigated farmlets (2200 to 4100 kg milk solids/ha). Almost all of these increases were attributed to the increases in grain and purchased fodder inputs associated with the increases in stocking rate. Net pasture accumulation rates and pasture harvest were generally not altered with stocking rate, though as stocking rate increased there was a change to more of the pasture being grazed and less conserved in both dryland and irrigated farmlets. Total pasture harvest averaged ~8 and 14 t DM/ha.year for dryland and irrigated pastures, respectively. An exception was at the highest stocking rate under irrigation, where pugging during winter was associated with a 14% reduction in annual pasture growth. There were several indications that these high stocking rates may not be sustainable without substantial changes in management practice. There were large and positive nutrient balances and associated increases in soil mineral content (P < 0.01), especially for phosphorus and nitrate nitrogen, with both stocking rate and succeeding years. Levels under irrigation were considerably higher (up to 90 and 240 mg/kg of soil for nitrate nitrogen and phosphorus, respectively) than under dryland pastures (60 and 140 mg/kg, respectively). Soil organic carbon levels did not change with stocking rate, indicating a high level of utilisation of forage grown. Weed ingress was also high (to 22% DM) in all treatments and especially in heavily stocked irrigated pastures during winter. It was concluded the higher stocking rates used exceeded those that are feasible for Mediterranean pastures in this environment and upper levels of stocking are suggested to be 2.5 cows/ha for dryland pastures and 5.2 cows/ha for irrigated pastures. To sustain these suggested stocking rates will require further development of management practices to avoid large increases in soil minerals and weed invasion of pastures.

1975 ◽  
Vol 15 (77) ◽  
pp. 740 ◽  
Author(s):  
RT Cowan ◽  
IJR Byford ◽  
TH Stobbs

Forty Friesian cows were grazed continuously on a green panic (Panicum maximum var. trichoglume)/glycine (Glycine wightii cv. Tinaroo) pasture at stocking rates of 1.3, 1.6, 1.9 and 2.5 cows ha-1 for two years on the Atherton Tableland, Queensland. A supplement of 3.6 kg crushed maize cow-1 day-1 was fed for 50 days post-partum to half the cows in each group in both years. Milk yield per cow was reduced from 3811 kg lactation-1 at 1.3 cows ha-l to 3289 kg lactation-1 at 2.5 cows ha-1. With increasing stocking rate milk yield per hectare increased linearly to 8309 kg ha-1 at 2.5 cows ha-1. At 1.9 and 2.5 cows ha-1 cows lost weight over the two years and in late lactation levels of milk solids were often low. Also at these stocking rates cows had to be supplemented for up to 60 days during the main dry season. Legume content of the pasture declined linearly (P < 0.05) with increasing stocking rates. Maize feeding in early lactation increased milk yield over the total lactation by approximately 12 per cent, the response being 2.3 kg milk per kg maize fed, Response was greater at lighter stocking rates as cows in the heavier stocking rate treatments dried off prematurely. It was concluded that per hectare milk production from tropical grass/legume pastures can approach that from temperate pastures and that energy supplementation early in lactation would substantially increase per cow production.


Author(s):  
J. Hodgson

Recent assessments of the relative importance of stocking rate. stocking policy and grazing management on the output from pastoral systems are used as a starting point to argue the need for objective pasture assessments to aid control of livestock enterprises to meet production targets. Variations in stocking rates, stocking policy and other management practices all provide alternative means of control of pasture conditions which are the major determinants of pasture and animal performance. Understanding of the influence of pasture conditions on systems performance should provide a better basis for management control and for Communication between farmers, extension officers and researchers. Keywords: Stocking rate, pasture condition, pasture cover


1977 ◽  
Vol 28 (1) ◽  
pp. 133 ◽  
Author(s):  
JP Langlands

Grass and milk consumption and liveweight changes of lambs grazed at stocking rates ranging from 9 to 35 sheep/ha were measured during a 105 day lactation. Grass consumption and wool production of their mothers and of similar ewes without lambs were also determined. The forage and total organic matter intakes of the lamb increased with time while milk consumption declined; all three variables were negatively correlated with stocking rate. The intake of the ewe and its liveweight gain were not sensitive to increasing stocking rate, but wool production declined at higher stocking rates. The maintenance requirement of the ewes was estimated to be 218 kJ metabolizable energy/kg liveweight, and the efficiency with which metabolizable energy was utilized for milk production was 66%. Lactation increased the intake of the ewe but reduced its wool production.


1985 ◽  
Vol 25 (3) ◽  
pp. 505 ◽  
Author(s):  
TM Davison ◽  
RT Cowan ◽  
RK Shepherd ◽  
P Martin

A 3-year experiment was conducted at Kairi Research Station on the Atherton Tablelands, Queensland, to determine the effects of stocking rate and applied nitrogen fertilizer on the pasture yield and composition, diet selection by cows, and soil fertility of Gatton panic (Panicum maximum cv. Gatton) pastures. Thirty-two Friesian cows were used in a 4x2 factorial design: four stocking rates (2.0, 2.5, 3.0 and 3.5 cows/ha), each at two rates of fertilizer application 200 and 400 kg N/ha.year. The higher rate of fertilization increased the pasture green dry matter on offer at all samplings (P < 0.01); the increase ranged from 1 106 kg/ha in summer to 548 kg/ha in spring. Green dry matter decreased ( P< 0.0 1) with increasing stocking rate, with mean yields of 3736 and 2384 kg/ha at 2.0 and 3.5 cows/ha, respectively. Weed yields increased over the 3 years at the higher stocking rates for pastures receiving 200 kg N/ha.year. The crude protein content of leaf and stem increased with increasing stocking rate and amount of applied nitrogen fertilizer. Values ranged from 12.1 to 26.5% of dry matter (DM) in leaf and from 3.7 to 13.8% DM in stem. In leaf, sodium concentration (range 0.05-0.20% DM) was increased, while phosphorus concentration (range 0.21-0.44% DM) was decreased by the higher rate of fertilizer application. Plant sodium and phosphorus levels were inadequate for high levels of milk production. Dietary leaf content and crude protein contents were consistently increased by both a reduced stocking rate, and the higher rate of fertilization. Cows were able to select for leaf and at the lowest stocking rate, leaf in the diet averaged 38%; while the leaf content of the pasture was 20%. Dietary leaf content ranged from 38 to 57% in summer and from 11 to 36% in winter. Dietary crude protein ranged from 13 to 15% in summer and from 7 to 11% in winter and was positively correlated with pasture crude protein content and dietary leaf percentage. Soil pH decreased (P<0.05) from an overall mean of 6.3 in 1976 to 6.1 at 200 N and 5.8 at 400 N in 1979. Soil phosphorus status remained stable, while calcium and magnesium levels were lower (P<0.01) after 3 years.


2000 ◽  
Vol 40 (2) ◽  
pp. 125 ◽  
Author(s):  
D. R. Kemp ◽  
P. M. Dowling

Naturalised pastures across the higher rainfall (>600 mm) perennial pasture zone of south-eastern Australia are less productive than they were, while sown pastures fail to maintain their initial levels of production. Several factors have contributed to this, including lack of knowledge of suitable grazing practices, weed invasion, increasing acid soils, rising water tables and poor management practices during droughts. A key issue in each case is the decline in perennial grass species which is both a cause and effect of the decline in productivity and sustainability of these ecosystems. This paper introduces a volume devoted to the largest collaborative study done to evaluate tactics for better grazing management and to improve the sustainability of perennial pasture ecosystems. Grazing practices to manage the composition of pastures have been largely neglected in pasture research, but are an important first step in improving pasture sustainability. This paper also outlines a new, open communal grazing experimental design which was developed and used across 24 sites on farms in New South Wales, Victoria, Tasmania and South Australia, to evaluate tactics for grazing management. The general aim across these experiments was to maintain (if adequate) or enhance (if degraded), the proportion of desirable perennial grasses in the sward to achieve more sustainable pastures. The results will provide the basis for building more sustainable grazing systems.


1967 ◽  
Vol 15 (3) ◽  
pp. 198-206
Author(s):  
J.P.H. Van der Veen

A trial was begun in 1963 at the Wadi al A'azib Range and Sheep Experiment Station to compare stocking rates of 9.0, 6.0 and 4.5 ha/sheep on animal production (liveweight of ram and ewe lambs, milk production and unwashed wool yield) and on the composition and density of the vegetation which was classified into 5 units: (a) valley stream-bed and floodplain on alluvial silt, (b) valley terrace on higher floodplain, (c) Artemisia herbaalba associations on marly soils, (d) Haloxylon articulation associations in small valleys and on hill-slopes, (e) Haloxylon articulatum/Noea mucronata associations on shallow, stony, grey desert soil on folded limestone hills. Fresh herbage yields in 1964 were 3129, 1126, 1312 and 859 kg/ha for areas (a), (b), (d) and (e), respectively. Average yields were lower at the higher stocking rate in the drought year 1966, but results were generally inconclusive. It was concluded that, pending further work, a stocking rate of 4.5 ha/adult ewe would not seriously deplete the grazable herbage.-M.G.W. (Abstract retrieved from CAB Abstracts by CABI’s permission)


Author(s):  
M.B. O'Connor ◽  
P.J. Tonkin ◽  
T.E. Ludecke

Parent materials such as volcanic ash and sedimentary siltstone and sandstone form soils which differ markedly in their physical and chemical properties. In stocking x fertilizer rate trials on two families of soils, Te Kuiti-Tumutumu (volcanic ash) and Mahoenui-Mangatea (siltstonesandstone) , the former showed marked response to increasing rates of superphosphate in terms of pasture availability and animal production but -the latter showed negligible response above :the lowest rate (250 kg/ha). Responses to superphosphate were apparent on Te Kuiti-Tumutumu only at the high stocking rate. Sward composition showed no measurable improvement with the application of superphosphate. Manage ment practices were undoubtedly important in this respect. Differential 'topdressing should be practised where feasible. When soil test levels for phosphate are medium to low, Te Kuiti-Tumutumu soils should receive at least 500 kg/ha/yr of superphosphate, Mahoenui-Mangatea soils 250 kg/ha/yr. Stocking rates and management practices must be such as to allow full utilization of the additional pasture grown.


1985 ◽  
Vol 36 (6) ◽  
pp. 845 ◽  
Author(s):  
TH Brown ◽  
GE Ford ◽  
DW Miller ◽  
I Beveridge

The effects of nematodiasis on productivity in weaner sheep was measured at Kybybolite Research Centre, South Australia, during 1976-81. Three levels of control were compared at two stocking rates (7.5 ha-1 and 16 ha-1). One group was not treated with anthelmintics, another group was treated every 3 weeks and the third group (Planned) was given five doses of anthelmintics each year: once in October, twice during the hot dry summer and twice during the winter months. The sheep were replaced by weaner sheep at shearing in October each year. The drenching regime of sheep on a particular paddock was the same for all five years. Nematodes, particularly Trichostrongylus spp., had a very large effect on the production of the sheep. The mean annual death rate of the untreated sheep was 22% and 56070, for the low and high stocking rates respectively. The regularly drenched sheep were 9-31% heavier and cut 11-46% more wool than the survivors of the untreated sheep at the low stocking rate. At the high stocking rate the regularly drenched sheep were 17-58% heavier and cut 14-56% more wool than the survivors of the undrenched sheep. The sheep given the Planned drenching program had similar final liveweights each year to the regularly drenched sheep, and in only two years out of five did the regularly drenched sheep produce significantly more wool than the sheep given the Planned program. The effect of drenching on the contamination of wool with faeces, and the resultant effect on the incidence of fly strike, is discussed. There was a significant variation between years in amount of available pasture, and there was generally slightly more pasture available on the Nil drench treatment paddocks.


1974 ◽  
Vol 14 (67) ◽  
pp. 155 ◽  
Author(s):  
RL Colman ◽  
AG Kaiser

Dairy production was measured over two lactations on kikuyu grass pastures fertilized with 336 kg N ha-1year-1, at stocking rates from 2.47 to 4.94 cows ha-1. Mean butterfat production per cow was low, varying from 72 to 109 kg, and declined by 6.1 kg per cow (P < 0.05) for a unit increase in stocking rate. Annual production per hectare was high, reaching a maximum of 448 kg butterfat and increasing by 72.6 kg ha-1 (P < 0.01) for a unit increase in stocking rate. A supplement of crushed oats was fed at the highest stocking rate during early lactation. This increased production by up to 20 per cent. The stability of the system is discussed in relation to pasture productivity, soil fertility and animal production.


2010 ◽  
Vol 50 (7) ◽  
pp. 705 ◽  
Author(s):  
R. G. Chataway ◽  
D. G. Barber ◽  
M. N. Callow

Dairy farms in Queensland were stratified by six regions, three levels of enterprise size (0.25–0.69, 0.7–1.39 or >1.4 ML milk/year) and two rainfall zones (<1000 and >1000 mm/year). Thirteen percent of farmers (89 farms) were surveyed using a prepared questionnaire to ascertain the current production systems, forage management practices and preferences for extension services. Herd size, dairy area, milk production per cow, the use of cropping, pit silage, concentrate input and irrigation input all increased (P < 0.05) with larger enterprises. At the same time the stocking rate on high milk volume farms was almost twice that on smaller farms. The drier zone (<1000 mm/year) was associated with lower stocking rate, higher per cow production and a greater emphasis on cropping and feedpad usage (P < 0.05). The importance of enterprise growth through intensification of the existing farm land resource base is indicated through these findings. Apart from ration formulation, processes used to manage cropping land, irrigation and grazing were primarily based on tradition or intuition. In valuing extension activities, farmers across all enterprise sizes were in general agreement that information products warranted only a small investment. As enterprise size increased, a more individualised and focussed extension service, delivered through targeted discussion groups and personal coaches was favoured.


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