Study on effect of feeding extruded soybean food on reproductive hormone profile in pet dogs.
Nutrition plays a complex and controversial role in Animal health. Today, the animal feed industry worldwide is becoming increasingly dependent upon vegetable protein sources. There are many hundreds of these bioactive plant chemicals found in dietary sources of fruits, vegetables, legumes, whole grains, nuts, seeds, herbs and spices. Isoflavones are a class of organic compounds and biomolecules related to the flavonoids . Increasing consumer awareness of soybean as a healthy food ingredient has led to a tremendous growth in sales of soy isoflavone-enriched foods and dietary supplements . Although the active components of soy proteins have not been clearly determined, a large number of studies have reported that isoflavones are the most beneficial group of soy components. Phytochemicals such as isoflavones occur naturally in plants and mostly in soybeans. Phytochemicals are bioactive compounds and are non-nutritive, as they do not play any nutritional role. They act as phytoestrogens in mammals. Isoflavones have the ability to behave as estrogen mimics, but also have other important non-hormonal properties that have attracted the attention of many investigators . After ingestion soybean isoflavones are hydrolyzed by intestinal glucosidases, which releases the aglycones, daidzein, genistein and glycitein. These may be absorbed or further metabolized to many specific metabolites, including equol and p-ethylpheno [1,9]. As indicated in fig-O1 and 02, the two primary
Isoflavones that are found in soybean foods are daidzein [4,7-dihydroxyisoflavone] and genistein (4', 5,7-trihydroxyisoflavone) and their respective glucosides, genistein (fig-O1) and daidzein (fig-02). Soybean foods typically contain more genistein than daidzein, although this ratio varies among different soybean products. Isoflavones have received a great deal of research on non-hormonal properties especially for possible cancer and heart disease-preventive properties . Though much attention by researchers was given to its beneficial effects, not much work was focused on phytoestrogens and its pseudo estrogenic activity  in pets when soybean is incorporated in pet foods. The objective of this study was to evaluate the use of extruded soybean in pet food formulations and its implications on dog's reproductivity.
Hence the studies were planned to understand the possible effects of extruded soybean enriched pet food feeding trials on dogs.
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The determinations of concentrations of hormones in biological fluids including plasma, urine, saliva and feces have been useful in determining the reproductive status of animals'. Although there are a number of factors that influence hormone concentrations, the hormone fluctuations do happen due to nature of food intake.
The feeding trials for 'pet food with extruded soyabean' was conducted on six adult cross- bred dogs aged approximately 30 months. The dogs ranged from 12 to 25 kilograms in body weight. This study was approved by the Institutional Animal Ethics Committee and all the dogs were cared for according to the principles outlined in the "CPCSEA GUIDELINES FOR LABORATORY ANIMAL FACILITY" & NIH Guide for the Care and Use of Laboratory Animals (NRC, 1985 (18)).
A. Study protocol
(i) Six healthy dogs of three male and three female were selected and housed separately.
(ii) 400 gram of pet food enriched with extruded soybean was offered simultaneously to all adult dogs in separate bowls along with water for a period of 52 weeks.
(iii) Before and after the trial period the dogs were examined for physical health condition.
(iv) The blood was collected 14 and serum seperated before taking for hormone analysis.
Testosterone levels in male dogs, progesterone and estrogen levels in female dogs were tested and the hormone levels of experimental dogs are compared with normal values.
B. Composition of the diet
A typical pet food formula consists of the following specifications and ingredients and the formulations are done as per regular maintenance diet [15,16,17] for dogs. The pet food formulation was done using the ingredients as mentioned in table-02 and to meet the product specifications indicated in table-O1. The ingredients such as extruded soybean, poultry byproduct meal, ground wheat, ground rice, rice bran, corn gluten meal, vitamin, mineral and salt mix were used to in the formulation. Ground wheat and rice were incorporated as starch additives, rice bran as source of fibre, soybean, poultry byproduct meal and corn gluten meal as protein sources. The composition of this formula was extruded and fed to the dogs to assess the effect of extruded soybean pet food on pets' re-productivity.
In this food interaction study, the mean average consumption of Pet food was 353g/day/dog as indicated in table-04. During feeding programme dogs maintained normal health and weight.
As indicated in table-03, the pet food consumption was recorded minimum of 345 g/day for dog No. 6 (native breed) and maximum of 363 g/day for dog No. 3 (cross bred) for whole feeding trial period of 52 weeks. As indicated in table-05, the testosterone levels in serum samples varied between 173 to 368 lug/dl for male dogs. In female dogs the progesterone levels varied between 0.67 to 4.76 qg/ml and estradiol levels remained constant at <10 ng/ml.
As indicated in Table-05, it was demonstrated that feeding of pet food did not influence the main sex hormones in serum of the dogs indicating that Pet food containing extruded soybean may not influence the serum progesterone, estrogen and testosterone levels. This discussion further supports the earlier studies of W. Gregory Dr., Urbana  where they demonstrated the negative or no effect of soy protein in rat reproductive system. The progesterone and estrogen levels of dogs are in normal range of 0.67 to 4.76 igg/ml and <10 bg/ml respectively as indicated in table-06 and as discussed by Foster & Smith, Inc . and Hase M. et.al . The serum testosterone levels are in the range of 173 to 368 ng/dl. Testosterone levels in dogs' range  from 10l00ng/dl during normal seasons. However, the range may increase depending upon peak reproductive seasons and climatic conditions. The results indicated that testosterone levels are similar to the values as observed in normal healthy dogs.
The objective of this study was to evaluate the use of extruded soybean in pet food formulations and its implications on dog's fertility profile. It is indicated through hormone serum levels that the main sex hormone were not affected by feeding the pet food containing extruded soybean for 52 weeks. Hence extruded soybean can be used in pet food formulations.
 Axelson M, Sjovall J, Gustafsson B, Setchell KDR. 1984, Soya- A dietary source of the non-steroidal oestrogen equol in humans and animals. J Endocrin, 102:49-56.
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B. Purushotham *, PM Radhakrishna (1), BS. Sherigara (2) and Shiva Kumar (1)
Department of Post Graduate Studies and Research in Industrial Chemistry, Kuvempu University, Shankaraghatta, Shimoga-577 451
* Tetragon Chemie Pvt. Ltd., IS 40, KHB colony, Yelahanka New Town, Bangalore-560106 Corresponding Author Email: email@example.com
(1) Research and Development Centre, Tetragon Chemie Pvt. Ltd., Bangalore
[2) Industrial chemistry, Kuvempu university
Table 01: Maintenance diet specifications for adult dog. Constituent % Specification Moisture 10.00 Crude protein 24.00 Crude fat 08.00 Crude fibre 05.00 Table 02: Pet food formulations. Sl. No. Ingredients Quantity (in %) 1. Extruded soybean 31 2. Ground wheat 36 3. Ground rice 5 4. Rice bran 2 5. Poultry by product meal 15 6. Corn gluten meal 5 7. Additives 0.5 8. Vitamins, Minerals and salt mix. 5 Table 03: Pet food feeding with average consumption details. Dog Age Daily average food consumption No. Breed (months) (g/day) month I II III IV V VI 1 C/B 8 350 340 361 346 355 365 2 C/B 8 349 352 370 352 352 353 3 C/B 8 370 365 375 367 365 365 4 C/B 8 345 355 365 345 355 355 5 C/B 48 350 360 340 367 340 320 6 Native 18 345 347 350 347 367 347 Dog Daily average food consumption No. (g/day) month VII VIII IX X XI X1I 1 355 346 357 360 355 356 2 353 354 359 344 350 369 3 364 354 360 345 365 366 4 344 340 355 343 358 357 5 365 354 350 356 349 349 6 335 357 335 335 348 330 C/B= Cross Bred breed Table 04: Average mean consumption of pet food. Dog Breed Age Mean average No. (months) consumption g 1 C/B 8 353.83 2 C/B 8 354.75 3 C/B 8 363.41 4 C/B 8 351.41 5 C/B 48 350.00 6 Native 18 345.25 Total mean consumption 353.00 C/B= Cross Bred breed Table 05: Hormone levels in experimental dogs after feeding trials. Dog Dog Age (months) Found value No. Testosterone Progesterone Estradiol ng/dl ng/ml ng/ml 1 C/B 8 358.67 -- -- 2 C/B 8 173.99 -- -- 3 C/B 8 368.63 -- -- 4 C/B 8 -- 4.76 <10 5 C/B 48 -- 1.24 <10 6 Native 18 -- 0.67 <10 C/B= Cross Bred breed Table 06: Progesterone and estrogen levels for breeding. * Day Estrogen Progesterone Level Level (ng/ml) -3 day High < 1 -2 day Moderate 2-3 -1 day Low 3-4 0 (ovulation) Low 5 +1 day -- > 5 +2 day -- > 5 +3 day -- > 5 +2-3 weeks -- 10-80 +62 day +/- 1 -- 2 +63 +/- 1 -- 1 * Foster & Smith, Inc Hormone Levels: Determining Breeding Times and Whelping Dates, Peteducation.com
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|Author:||Purushotham, B.; Radhakrishna, P.M.; Sherigara, B.S.; Kumar, Shiva|
|Publication:||International Journal of Biotechnology & Biochemistry|
|Date:||Sep 1, 2009|
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