Key Points:

• POSILAC^® has consistently increased milk yields in a wide range of management systems.
• Countries around the globe have determined that bST is safe.

POSILAC has been evaluated on dairy farms in many countries worldwide (see Table 1 for responses obtained during administration of POSILAC in different countries). Commercialization commenced in South Africa in 1989 and more recently has been widely distributed in Brazil, Mexico and Jamaica. POSILAC has consistently increased milk yields in a wide range of management systems. In South Africa and many of the farms in Mexico, management was similar to much of the U.S. with a high level of grain feeding complementing basal diets of alfalfa and corn silage. Milk yields and milk yield responses to POSILAC were also similar to our field trial experiences in the U.S., ranging from 6 to 14 lbs/cow/day. In Jamaica, the Jamaican Hope, which is a cross-bred cow (Jersey X Zebu), is the predominant breed. The Jamaican Hope grazes African Star grass pastures and is supplemented with some concentrates in the milk parlor. Milk yields are low compared to the U.S., typically averaging around 20 to 25 lbs/cow/day. Responses to POSILAC have been in the range 3 to 6 lbs/cow/day.

In Brazil, the dairy industry ranges from sophisticated dairies utilizing top Holstein genetics to unsophisticated dairies in which the major source of feed is tropical pastures. POSILAC has been used successfully in both situations, but, as expected, the responses tend to be higher in the better managed dairies.

Table 1
Milk yield response to POSILAC in different countries

Animal protein is in short supply in many parts of the world, and particularly in Africa. POSILAC has been evaluated in Zimbabwe in both commercial dairies where cows yield up to 50 lbs/cow/day and in small farms which are lower input operations where cows typically yield 10 to 20 lbs/cow/day. In both cases, the increased milk production was about 20%. Remarkably, a similar percentage increase has also been observed in N'Dame cattle which suckle a calf, feed by foraging the limited native pastures, and yield about 2 lbs/cow/day.

Of equal importance to the immediate increase in milk yield is the effect of POSILAC on the persistency or duration of lactation. In fact, the increase in persistency of lactations in Bos indicus breeds in Zimbabwe has resulted in up to fourfold increases in milk yields.

Although the appropriateness and value of POSILAC in the poorest of African countries is still being assessed, it is a product of high technology which is extremely simple to use. Small landholders have no problems giving their cows a shot once every two weeks with 20%-30% increases in milk production. No changes in management were implemented with cows continuing to receive the normal types of feed. What is certain is that any technology which can increase dairy production must be fully explored if the protein-deficient diets of most Africans are to be improved.

For six years studies were conducted with POSILAC in Russia, the Ukraine, Bulgaria and Czechoslovakia. Trials have been conducted at both academic institutions and state farms with increases in milk yield ranging from 15%-25%. POSILAC has been approved for commercial sale in all four countries, although use has been limited due to the turbulent and rapid changes occurring in this world area.

POSILAC has been fully evaluated in clinical trials in the United Kingdom, France, Germany and the Netherlands. These studies began in 1985 and some cows received POSILAC for up to five consecutive lactations (the United Kingdom). As in all other countries, the safety of milk from cows supplemented with bST has never been an issue and milk from the trials was marketed through normal channels. Furthermore, in early 1993 the 12 countries of the EC unanimously agreed that POSILAC was safe and effective for dairy cows and was approved on a technical-scientific basis. However, the so-called "fourth hurdle," or the assessment of a socio-economic need for bST in a situation where there is currently an oversupply of dairy products in Western Europe, led the political bodies of the EC to declare a moratorium on the commercial sale of bST within the EC until December 1994.

Reference

1. Phipps RH, Madakadze C, Mutsvangwa T, Hard DL, and Kerchove G: Use of bovine somatotropin in the tropics; the effect of sometribove on milk production of Bos indicus, dairy cross-bred and Bos taurus cows in Zimbabwe. J Agri Sci 1991;117:257.

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