NEWS another measure of stocking rate – total liveweight per irrigation corrected hectare . I did this by counting each irrigated hectare as one hectare , and each dryland hectare as half a hectare . Using the irrigation corrected stocking rate , I found that higher stocking rates are associated with ( see Table 5 for actual results ):
• all the same results as in the previous two analyses , except for nitrogen use efficiency , which was not correlated with stocking rate , and as with the first analysis , gross margin per litre was not correlated with stocking rate
• lower production of milk solids ( kg solids / 100 kg weight )
• higher concentrates fed to the cows in milk per litre of milk ( g / l )
• lower phosphorous fertiliser application rates ( kg P / ha )
• higher cost of feed ( R / l )
Figure 2 . An example of a disadvantage of higher stocking rates is the negative correlation with pasture utilisation .
These results are indicative of the stocking rate dilemma being a little bit more complicated than purely a higher stocking rate is better . The results still point towards a higher stocking rate being more profitable , but it also shows a higher cost to milk production . Many people might say that doesn ’ t matter because it is still more profitable , but a higher cost of production is a dangerous path in the long term because it means more risk of exposure to inflation . This is a big reality in South Africa and must be taken into consideration when deciding on the most sustainable farm system for the future .
The role of pasture
I decided to explore this dilemma further . A seemingly clear assumption is that the lower the stocking rate , the more pasture there will be available for each animal on the farm . This should mean greater profitability . But is this the case ? It seems a bit more complicated than that in view of the data which has been presented in this case study .
Figure 3 . An important reason to provide as much pasture per cow as possible is that it is associated with a lower cost of feed per litre produced .
above , therefore showing that the trend discussed above is true even when we use a smaller dataset with more directly compared farm systems
• higher gross margin per litre , which was not found in the previous data set
These results further strengthen the argument for a higher stocking rate being better .
One of the factors that could skew these results is that farms which are able to have a higher stocking rate are the ones which have more irrigated areas . When looking at the results in terms of stocking rate per irrigation corrected hectare . To overcome this bias I added
I decided to calculate a figure for how much pasture there is grown and therefore available for each animal – kilogram of pasture per kilogram of liveweight on the farm . I wanted to see how this figure correlated with the other parameters . The more pasture there is available per animal the ( see Table 6 for actual results ):
• lower the stocking rate , both in terms of total hectares ( kg weight / ha ), and in terms of irrigation corrected hectares ( kg weight / irrigation corrected ha )
• higher the milk solids ( kg solids / 100 kg weight )
• lower concentrates fed to the cows
15 Grassroots Vol 22 No 2 July 2022