The experimental variable considered for this study was weight gain average. On the basis of an expected average difference of weight gain of 11 kg, with a standard deviation of 9,5 kg under 5% confidence level and with 80% of statistical power, a minimum sample size of 14 animals was calculated for each experimental group. Each animal was considered an experimental unit. Thus, 40 Nelore bulls with an average age of 25 + 7.7 month bulls with a 211.08 + 41.7 kg as initial average weight, were randomly assigned to two experimental groups of 20 animals each. However, there were 4 withdrawals in control group at the beginning of the study. The weight of for a animal was monitored every 15 days during a 90-day period. This trial was run from September to January, for a 105-day period. The treatment consisted of 3 injections of 1 mL of Modivitasan for every 50 kg of body weight repeated at 30-day intervals, being the first administration on day 1, the second one on day 30 and the last one on day 60. The results presented at Table 1 show a signicant statistical difference on the final weight gain value for the treatment group compared to the control group. This way, existence of higher weight gain has been evidenced, 13.3 kg weight average which favors the animals that were administered with the organic modifier, Modivitasan, as it is observed in Picture 1. This increase of weight gain could be explained by the supply of minerals, energy, vitamins and amino acids contained within this organic modifier. Weight gain comparison The averages were statistically different (p<0.01)
The averages were statistically similar (p=0.21) Weight gaining Treatment Group and Control Group Experimental Group By the end of this trial the average weight gain shows an increase of 44% for the treatment group compared to the control group.
Despite of poor quality pastures, daily weight gain was 0,482 kg in the Treatment Group compared to the Control Group which reached an average daily weight gain of 0,334 kg. An increase of the voluntary food intake can be attributed to energy, vitamin and protein contribution of Modivitasan, due voluntary intake and digestibility respond to protein and energetic supply when pastures contain less than 8 to 10% of crude protein, which is the case of the pastures used for this trial (Allison, 1985; Del Curto et al., 1990). Weight gain comparison Study On the other hand, it must be emphasized that the obtained weight gain has a positive effect over breeder's economy according to a simple economic analysis. Considering a treatment of Modivitasan for 3 PEN (1.10 USD aprox.) per animal for each injection, the sale price of 4 PEN (1.5 USD aprox.) per kg of body weight and; 43.4 kg and 30,1 kg as the weight gain average for the treatment group and control group respectively, we have a 44.2 PEN (16.10 USD aprox.) net prot with the use of Modivitasan (Picture 2). Economic gain per animal by using Modivitasan Study 1. Allison CD. 1985. Factors affecting forage intake by range ruminants: a review. J. Range Manage. 12(3): 38-305.
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