I’m sure you’ve heard of the saying, “a chain is only as strong as its weakest link”. The same goes for animal nutrition and tending to the most limiting nutrient in a production system. In our previous blogs on why you should be supplementing your herd and understanding the different phosphorous sources, we touched on the theory of Liebig’s Law of Minimums. It states that livestock growth and development is determined by the nutrient that is most limiting or scarce. 


Picture a wine barrel where each plank represents an important macro or micronutrient that your herd requires…energy, protein, calcium, phosphorous etc. The height of each plank that forms the structure of the wine barrel varies depending on the nutrient availability from the pasture. Now imagine you start to fill the barrel and the protein availability in the pasture is lower than the availability of energy and other macronutrients. This results in a shorter plank and consequently the water leaks out over the protein plank. The height of this plank is the determining factor in the outcome or efficacy of the production system. If a protein source is supplied through a form of supplementation (and effectively patched up), the next limiting factor is often energy available and the constraint of minimums continues.  

Let’s take a look at a standard dry season in Northern Australia. As the season progresses after the wet, the body of grass that was once green and lush begins to turn brown and dry off. As the grass dries off and lignifies, protein becomes the first major limiting nutrient and must be addressed in order for your herd to utilise the feed and maintain the health of rumen microbes. This, of course, is where supplementation enters the situation. Water supplementation is perhaps the most targeted form of supplementation for livestock in the North as it addresses acute deficiencies directly in order to fix the most limiting nutrient. Protein supplements (i.e. urea supplements) are the most cost-effective source of protein available that can address the protein shortage in the dry season. 

Photos courtesy of Eloise Moir DAF Cloncurry