How is rbst administered

A pproval of this product has been subject to controversy in this country since the early s, primarily because of its possible effects on human health. The various House of Commons and Senate committees with an interest in the subject have regularly examined the issue and held hearings on it.

I n January , Canada decided not to approve the sale or use of rbST in Canada, having concluded that rbST had harmful effects on the health of animals to which it was given. From , from this the time of the first application for approval of an rbST-based product until the decision by Health Canada, the department responsible for approval, 11 years had passed. T his document presents various issues relating to rbST and considers its effects on health and the dairy industry, its regulation in Canada, and its use abroad.

B ovine somatotropin bST , which is also called bovine growth hormone, is a natural hormone produced in the pituitary glands of cattle, which stimulates growth in calves and lactation in adult cows.

A relationship has been found between the quantity of bST present in cows and their milk production. T he hormone bST, which is present in milk, is, like any other protein, broken down in the digestion process. It is also destroyed to a large extent by pasteurization. U ntil the s, the only means of obtaining rbST was to produce an extract from the pituitary glands of dead animals -- just as the insulin required by individuals suffering from diabetes was originally taken from the pancreas of human cadavers.

However, the limited amounts of the product obtained in this way and its impurity meant that it could never be used commercially. R ecombinant bovine somatotropin rbST is simply bST produced "outside the animal. This process, which is the same as that used to produce insulin, makes it possible to obtain large quantities of a very pure product.

T he rbST produced by pharmaceutical companies differs only very slightly from naturally occurring bovine somatotropin.

Although it is possible in theory to detect the presence of rbST in cattle, it is very difficult to do so in practice. At the present time there is no practical method of testing for its presence in milk or blood serum, either directly or indirectly. T he effects of rbST on human and animal health are still controversial. The following facts are generally accepted. Where the overall composition of milk is concerned mineral, vitamin, protein and lactose content, for example , no difference has been observed between milk from rbST-treated cows and milk from untreated cows.

Nor has a higher concentration of rbST been observed in the milk of rbST-treated cows. Thus the quantity of rbST contained in milk is the same whether or not the cows have been given rbST. However, according to the Monsanto submission in the United Kingdom, IGF-1 concentrations in the milk of rbST-treated cows could be five times higher than concentrations in the milk of untreated cows. T he following organizations have concluded that milk from cows treated with rbST in accordance with sound veterinary practices does not constitute a risk to human health:.

N evertheless, some points are worth considering, particularly the activity of rbST and IGF-1 in the human body. S ome observers claim that rbST, like any other protein, is broken down in the digestive tract where, since it is specific to cattle, it is inactive in humans.

It is also claimed that IGF-1 is broken down in the digestive tract and thereby becomes biologically inactive. A day study on sub-chronic exposure in rats was submitted by Monsanto; it showed that, after high doses were given orally, rbST could be absorbed intact from the digestive tract and cause an immune response. The consequences of this observation have not been fully assessed by the HSD.

A lso according to the Health Canada report, recent experimental data indicate that IGF-1 can survive in the digestive tract and be absorbed intact, particularly when ingested with milk proteins. IGF-1 absorption after milk consumption should not increase IGF-1 concentration in the body or its organs, even if all the IGF-1 present in the milk is absorbed within the digestive tract. T he effects of the increased use of antibiotics for cows to counter the increased incidence of mastitis caused by rbST use are also a subject of concern see the section entitled Animal Health.

In February , the Joint FAO-WHO Expert Committee on Food Additives studied the possible contamination of milk as a result of the increased incidence of mastitis and the resulting increased use of antibiotics for cows. It concluded that the use of rbST does not increase the risk to human health when antibiotics are used to treat mastitis, and that possible higher concentrations of antibiotic residues in milk can be managed using existing dairy industry practices.

The possibility of emerging resistance to antibiotics in pathogens transmissible to humans has not been studied. I n mid, Health Canada commissioned an expert panel, working under the auspices of the Royal College of Physicians and Surgeons of Canada, to evaluate whether rbST was harmful to human health.

In its January report, the panel reached the following conclusions. If the results of the day study on rats carried out by the rbST manufacturer are valid, there is a possibility of an allergic reaction in humans who consume products from animals that have been given rbST.

The panel therefore recommended that the study be carried out again in order to clarify this point. There is no plausible biological basis for concluding that an increased concentration of IGF-1 in milk causes immune responses, changes in the intestinal development of newborns, or risks of cancer among consumers of products from animals that have been given rbST. At present there is no evidence that oral absorption of IGF-1 is carcinogenic. Although IGF-1 plays a role in the development of certain forms of cancer, Health Canada has not asked the rbST manufacturer for an additional study on risks of cancer.

Any increased exposure of bacteria to antibiotics resulting from mastitis related to use of rbST is marginal in comparison with the exposure resulting from other agricultural and human uses. Thus it is unlikely that rbST has an impact on increased resistance to antibiotics. At this time, it is not clear that drinking milk, produced with or without rBGH treatment, increases blood IGF-1 levels into a range that might be of concern regarding cancer risk or other health effects.

These were:. At least 8 other national and international review committees have evaluated the evidence concerning potential health effects of rBGH on humans and dairy cows. These reviews and the most recent year they convened are listed below.

Several of these reports document adverse effects on cows, including higher rates of mastitis, foot problems, and injection site reactions. Although the use of rBGH is still approved in the United States, demand for the product has decreased in recent years. Many large grocery store chains no longer carry milk from cows treated with rBGH.

The available evidence shows that the use of rBGH can cause adverse health effects in cows. Only 30 of these are actually FDA approved. Some of these drugs are used illegally to treat mastitis and even Monsanto used a number of drugs illegally in their trials of rBST. Given this widespread use of unapproved drugs, Hansen questions whether the FDA can effectively enforce its safety standards for drug residues in milk.

Hansen notes that only four of six beta lactams are subject to testing in each milk tanker load, and though FDA has expanded its monitoring program, it still only tests for 12 drugs, notifies dairies in advance of sampling, and takes only about samples per year. Increased mastitis, Hansen argues, will lead to increased use of antibiotics the control over which is too limited. IGF insulin-like growth factors is a natural substance that mediates the effects of growth hormones in cows and humans.

The molecular structure of bovine IGF-1 and human IGF are identical, and since the chemical is not species specific the impact of increased levels due to rBST is important. IGF-1 content in milk varies over the lactation cycle and between cows in their first or subsequent cycle.

The study maintains that the amounts of IGF-1 in cows administered rBST are within the normal of that found in untreated cows. Opponents of rBST use maintain that elevated levels of IGF-1 can lead to a disease called acromegaly which results in enlargement of hands, feet, nose and chin; glucose intolerance, and hypertension. The Consumer Policy Institute maintains that recent evidence suggests a potential link between IGF-1 and cancer and tumor growth.

Epstein, letter to FDA commissioner D. Another study, not referred to in the Science article, that took place near the end of the lactation cycle when IGF-1 levels are normally at a minimum , revealed IGF-1 levels at least 3.

Hansen notes that a problem with virtually all studies is that a number of investigators have recently shown that the most common IGF-1 test is unreliable. It cites a study that suggests IGF-1 in milk can survive the human digestive tract and be taken up by the body. According to the institute, the study found that IGF-1 stimulates growth in cultures of epithelial cells lining the intestine.

The institute also disagrees with the conclusions and finds fault with the reasoning of a Monsanto sponsored study to determine whether IGF-1 is orally active in normal rats. The study was relied on by the FDA. The institute concludes:. In sum, we believe that the lone oral feeding study involving normal rats described in Science , is a poor study that appears to have been designed to minimize the chance of finding IGF-1 to be orally active.

In spite of this, the study contains suggestive data that IGF-1 may be orally active. This, combined with the facts that IGF-1 stimulates growth and division of epidermal cells in the intestine and has also been associated with colon tumor growth and, potentially, with human epidermal carcinoma, suggests that until we know more about the role of IGF-1, extreme caution should be exercised. Among these foods are supplements that come from rendering animals.

Blood samples were collected every seven days, from day 90 of gestation until day prepartum pre-induction. During feed restriction days to of gestation , blood samples were collected twice a day. From day until the parturition post-induction period blood samples were collected every 3 days.

Thumbnail Table 1. Chemical composition of the commercial supplement. Blood samples were taken weekly during 8 weeks postpartum. The samples from all animals were collected into two tubes, with EDTA and potassium fluoride for analysis of glucose and one without anticoagulant to obtain serum for further analysis and centrifuged at 1.

Lamb blood was also collected for analysis of the same metabolites described before in addition to total protein TP Labtest Diagnostica SA, Brazil in the first 24 hours after birth and seven days later. The lamb body weight was evaluated at 24 hours of age and then every 7 days for 7 weeks. From the start of rbST injections all animals were monitored daily. During the induction period, clinical evaluation of all females was performed, evaluating the heart and respiratory rate, ruminal movements, rectal temperature, and color of mucous membranes.

The data analysis was performed using the Statistical Analysis System Statistical Only one ewe in the control group had signs of clinical ketosis and therefore it was removed from the experiment. There was only single lambing in both groups during this study. There were three pregnancy losses after the induction period, all in the control group, representing a rate of There was no difference between periods for the metabolites measured Table 2.

Figure 1. It was observed that prepartum administration of rbST did not affect most of the blood biochemical parameters analyzed in pregnant ewes. Moreover, the greater body weight gain of lambs from dams receiving rbST in prepartum was also very relevant, observed already in the second week of life, which is probably due to better milk production of these dams.

During the induction of ketosis an increase in serum BHB was observed for all ewes, confirming the occurrence of ketosis subclinical BHB blood levels above 0.