Addah, W., Baah, J., Groenewegen, P., Okine, E. K. and McAllister, T. A. 2011. Comparison of the fermentation characteristics, aerobic stability and nutritive value of barley and corn silages ensiled with or without a mixed bacterial inoculant. Can. J. Anim. Sci. 91: 133–146. Barley (Hordeum vulgare L.) and corn (Zea mays) silage are the most commonly used forages in feedlot diets in western Canada, and are often inoculated in an effort to improve their preservation and quality. However, the relative value of these two forages in feedlot diets or their responses to inoculation have not previously been compared. Whole-crop barley (B) and corn (C) forage were ensiled for 63 and 77 d, respectively, in both mini silos and Ag Bags® without and with inoculation [Lactobacillus plantarum, Enterococcus faecium, Pediococcus acidilactici at 1.0×105 CFU g-1 forage; inoculated barley (IB), inoculated corn (IC)]. At the end of the ensiling period in mini silos, the pH of C and IC was lower (P<0.001) than B and IB silage, but lactate:acetate was higher (P<0.001) in IB than other silages (8:1 vs. ∼4:1). Inoculation did not affect dry matter (DM) loss during ensiling, but losses in barley were higher (P<0.001) than in corn silage. Barley silage appeared to be more stable than corn after 2 d of aerobic exposure. Inoculation of barley or corn did not affect in situ organic matter disappearance (OMD) or DM intake, average daily gain (ADG) or feed efficiency of steers. However, steers fed barley silage had a higher (P=0.037) DM intake, ADG (P=0.002) and improved (P=0.002) feed efficiency compared with those fed corn silage. The inoculant was more effective at improving the fermentation and aerobic stability of barley as compared with corn, and growth and feed efficiency of cattle fed barley silage was superior to those fed corn silage.

Hypophysectomized male Sprague-Dawley rats were fed milk from cows treated with recombinant bovine somatotropin (bST) to determine whether immunoreactive bST in milk has a growth-promoting effect following oral ingestion. The first three treatment groups were fed either 1) milk from control cows, 2) milk from control cows with 500 ng bST/mL added directly to the milk or 3) milk from bST-treated cows. Treatments 4, 5 and 6 were the same as 1, 2 and 3, respectively, except that the milk was heat-treated before being fed. Although injection of bST into hypophysectomized rats (0, 5, 20 or 80 micrograms bST/d) resulted in a dose-dependent response in average daily weight gain, width of the tibial epiphyseal growth plate and fractional weights of selected organs, ingestion of milk containing added bST (resulting in intakes of 1.3 +/- 0.03 mg bST/d) had no effect on these growth indices. Levels of immunoreactive bST in milk from bST-treated cows were not significantly different from those of untreated cows (4.2 +/- 1.9 ng/mL versus 3.3 +/- 1.7 ng/mL, respectively, p greater than 0.05). Heat treatment reduced the immunoreactive quantities of bST in milk by 85 to 90% (p less than 0.001). Feeding heat-treated milk to hypophysectomized rats resulted in reduced liver weights (p less than 0.001) compared to those of similar rats fed milk that was not treated by heat. The effects of milk from bST-treated cows were not different from those of milk from untreated cows following oral ingestion by hypophysectomized rats.

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The use of exogenous hormones to etrhance human consumption. One question being animal produciion has prompted concern asked is whether use of recombinant bovine regarding the relative safety of food for somatotropin (rbST)

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