NEWS
Table 5 . Correlations between stocking rate and various profitability , productivity , and sustainability indicators using data from the Trace & Save research database on farms which raise heifers on the farm and do not grow any home-grown roughage , and have predominantly pasture areas ( n = 176 ).
Table 6 . Correlations between pasture grown per cow and various profitability , productivity , and sustainability indicators using data from the Trace & Save research database on all the farms which raise heifers on the farm ( n = 316 ) from the other farms ( see Table 8 for actual results ).
Some of the other differences which are not statistically significant , but are still important to point out since any farmer would recognise that these results are meaningful , are presented in Table 3 below .
I find these results to be fascinating in our quest to understand stocking rates better . Other than higher stocking rates , there are some very important additional aspects of their farms . Although the stocking rates of these farms are higher than the rest of the farms , their stocking rate is nowhere close to as high as the highest stocking rate farms in the previous analysis ( i . e . 1 933 vs 2 277 kg weight / ha ). And the stocking rate per irrigation corrected hectare , although higher , was not statistically significantly higher on these top-performing farms . Chasing the highest possible stocking rate is not the answer . Too low of a stocking rate is an obvious problem , but so too is too high of a stocking rate .
fertiliser per litre is lower than the rest of the farms . Only the gross margin per hectare is higher on the higher stocking rate farms , not the gross margin per litre , so there is still the issue of exposure to the risk of inflation . The biggest reason for this is the high feed that is still being relied upon on these farms .
The holistic , sustainable farm system
I have one more step to explore in this data , since just looking at the highest stocking rate farms did not yield much extra insight . Once again using the smaller 176 farm dataset , I used four measures to rank farms : gross margin per litre ; gross margin per hectare ; carbon footprint ; and nitrogen use efficiency . I ranked all the observations from
1-176 for each measure . Then I looked at which observations were in the top third ( i . e . top 33 %) in all four categories . This resulted in 15 observations ( out of interest from 10 different farms ) of farms which I would argue are the most sustainable based on overall measures . Hence , they are the farms we should be looking to as examples of an ideal system .
Using these 15 observations I wanted to see if there was anything to learn from their stocking rates and other parameters . So I compared the average of all the parameters we have been looking at between these 15 observations and the other 161 observations ( using a Mann-Whitney U test ). The best-performing farms were distinct
One of the distinct advantages of a higher stocking rate throughout this case study has been that a higher stocking rate is associated with a higher gross margin per hectare . These 15 observations show that a more balanced approach blows a high stocking rate out of the water . These farms had an average gross margin of R81 619 R / ha , whereas the average for the highest stocking rate farms was R68 601 . And these topperforming farms had a much higher gross margin per litre as well .
The important things that these topperforming farms were able to achieve , which are different to the highest stocking rate farms , are a combination of :
• Optimal milk production – better milk production per weight and higher solids per weight are important aspects of a sustainable dairy farm . Since these are not correlated with stocking , they are independent of the stocking rate and are therefore an important distinguishing factor on top-performing farms .
• Better feed conversion in terms of lower concentrates , lower proportion of bought feed , higher pasture utilisation and lower cost of feed . This is also a different balance than what is found with high stocking rates . This means these farms buck the trend of less pasture with higher stocking rates , which allows them to get away with less bought feed and hence a lower cost of feed . This is such an important distinction . The danger of too high stocking rate is too high cost of bought feed . Farmers must figure out how to strike
17 Grassroots Vol 22 No 2 July 2022