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Part 1 | rbST: Friend or Foe

Updated: Aug 10, 2022

In recent years, the dairy industry has become more aware of the rising input costs faced on farms. With monthly increases in feed and fuel costs, it is becoming harder for farmers to produce milk profitably.

How can farmers improve their profitability? The effects and benefits of improved genetics, nutrition, and management changes take time to make themselves felt. In this article, we offer farmers a solution technology, more specifically biotechnology.

If we look at products such as rennin (used in cheese production), lactase (used in lactose-free milk), and insulin for diabetes, it becomes apparent that biotechnology is used in everyday processes. Let us discuss a controversial product, recombinant

bovine somatropin (rbST).

What is bST and where does it come from?

Bovine somatropin (rbST) is a protein hormone that is produced in the pituitary gland of cows. Protein hormones are made from chains of amino acids that are broken down into amino acids by the gut once consumed Bovine somatropin is made up of 191 amino acids and is biologically equivalent to natural bST produced by the cow, except for one amino acid at one end (methionine).

As early as the 1920s, bovine somatropin was used in studies to improve animal performance during food shortages. In the 1970s, the scientists DE Bauman and WB Currie from Cornell University continued their investigation of this hormone. Bauman’s group showed that pituitary-derived bST had a significant effect on milk yield, even in high producing cows.

During this period, they were using biotechnology – the development of recombinant DNA. Companies such as Monsanto and Genentech committed to producing bST through recombinant technology. They produced the first successful rbST. Bauman’s

group did the first study in December 1981. The supply increased and universities, governments, and industries worldwide started their own studies on rbST. In November 1993, the Food and Drug Administration in the United States approved rbST for commercial use in animals. In South Africa, Lactatropin is distributed by Lionel's Veterinary Supplies.

Why is rbST important for South African farmers?

Farmers are struggling to deal with rising input costs.

Firstly, bST is a natural hormone and major regulator in milk production. It coordinates metabolism, allowing more nutrients for milk production in animals. During calving, the cow naturally produces BST, which is transported to the liver where it is metabolised into an insulin-like growth factor 1 (IGF-1), which is used in various systems and organs throughout the body. A cow will reach peak production around 60 days into lactation. The cow is producing her maximum natural bST levels at this point and these levels will start to decrease as her lactation continues.

Recombinant bovine somatropin is administered at 60 days of a cow’s lactation cycle when milk production normally begins to decrease, and is repeated every 14 days until two weeks before dry-off. Maintaining peak production for longer will result in higher milk yield per cow per day over the entire lactation period.

Lactatropin is a slow-releasing plant oil formulation. An average response of 4,5 kg extra milk per cow per day and about 1 000 litres of milk per cow in total lactation yield can be expected. Lactatropin can make the entire herd perform more like the high-yielding cows, and thereby increase productivity.

Secondly, rbST decreases the carbon footprint on farms by 8–9% per 3,8 litres of milk, while increasing milk production. By increasing milk yield without increasing the number of animals and maintaining the same milk yield, we limit the environmental effect of dairying. This will increase production efficiency and decrease the production of methane and greenhouse gases from manure and land erosion.

In our next article, we will discuss the different factors involved in the use of rbST on dairy cattle.

Milk production improvement due to rbST on a South African pasture farm

Reference: Bauman, D. 2015. Facts about recombinant bovine somatotropin (rbST). Date of Access: 16 Mar. 2022


Enquiries about rbST or Lactatropin: Please contact Frances Roos on 021 932 2019 or

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