MATERIALS AND METHODS

This research was time schedule from November, 2010 up to June, 2011 in Shahroud commercial dairy farms. There were questionnaires for this purpose which distributed among 65 commercial dairy farms from which we could find required information about 50 herds for our further analysis. The first part of that questionnaire includes necessary information about managerial strategies considered to manage cows in transition period and for prevention from acidosis metabolic disorder including pay attention to fiber importance and proper fiber ratio to concentrate in transition period’s diets, increase of feeding frequency in day and benefiting from sodium bicarbonate for facilitation of buffering of rumen. Also the application or implementation costs of these strategies have been measured in this part as well.

The next part is about relevant information of incidence rate of acidosis by relying upon clinical sign and hygienic and treatment records and also acidosis therapeutic costs for each cow. The next part of questionnaire is related to producing and economic information including average production parameters per cow and also gross income of milk sale in each lactation cycle. The last part of questionnaire is related to reproductional records, average fertility and its costs.Upon regulating the obtained information it was possible to analysis the factors through Multiple Linear Regression method (MLR) and by statistical SAS 9.1 software with following model:

Furthermore we could measure correlation rate of effective managerial strategies on acidosis and related variables through Correlation method and by SAS software as well.

Following is the related model of this study:

RESULTS AND DISCUSSION

In this part we may separate the type and any effects of mentioned items on economic and managerial variables.

Pay attention to the importance of fiber and following up the suitable rate of which with concentrate in rations of transition period: Generally 70% of cattlemen had good knowledge about the importance of fiber regulation and its correct rate with concentrate throughout Shahroud commercial dairy farms. They applied this subject after calving and under supervision of nutrition advisor for relevant diets. But 30% of them were unfamiliar and had no information in this regard. The results of analysis of variance upon applying of Multiple Linear Regression method (MLR) made it clear that any applying of this managerial strategy has a significant effect on variables of acidosis incidence rate, treatment costs, average production, fertility costs (p<0.01) and average fertility (p<0.05). But it did not have a statistically significant effect on gross income parameter (p>0.05) (Table 1).

The mentioned findings are in compliance with the obtained results by Seyyed-Almusavi et al. (2008) who did consider that improper ration balancing on Total Mixed Ration (TMR), ignoring PeNDF and physical effective fiber in rate, chopping or processing more than limited parts of the diets as the major factors of acidosis. Also these findings may confirm the obtained results by Haghparvar et al. (2008) who stated that in order to have acidosis control it is necessary to change the ration gradually plus feeding with high forage and incomplete processed grains for prevention from acidosis epidemy.

Table 1:	The effect of managerial strategies to prevention from acidosis on economical and managerial variables
**Significant difference (p<0.01), *Significant difference (p<0.05), nsNon Significant differences (p>0.05)

Hoseini-Nejad et al. (2008), stated that high grain rations and low forage instead of increasing the efficiency may cause twine problems with acidosis such as reducing of milk production, digestive diseases, laminitis and undesirable cullings. It has been stated in a report made by American National Research Center (NRC, 2001) that high forage and low fiber may even increase milk production but may cause some metabolic disorders such as rumen acidosis, laminitis and milk fat syndrome. Krause et al. (2002) and Teimouri-Yansari et al. (2004) stated that any increase in chewing activity resulted from increase PeNDF consumption may cause an increase in pH of rumen and facilitate the reduction of acidosis in dairy farms. Yang and Beauchemin (2009) specified that any increase of rumen acidosis after PeNDF increase is not only under the effect of chewing but is related to betterment of rumen circumstances.

Also the results of average comparision show that there is statistical significant difference between studied groups and about incidence rate of acidosis and relevant treatment costs (p<0.05). But there is not a significant difference between both groups from average production, gross income, average fertility and fertility costs (p>0.05) (Table 1).

Also according to the study of correlation coefficient between current variables and other managerial and economic indices, it was specified that pay attention to fiber and its suitable rate with ration concentrate has an extra ordinary relation with reduction of acidosis incidence (r = -0.91). We could calculate the relation between this managerial strategy with treatment costs by Pearson correlation coefficient (r = -0.80) which is a sign of its role in reduction of acidosis treatment costs. Furthermore we could obtain the correlation coefficient for this variable and average production (r = 0.56), gross income (r = 0.27), average fertility (r = 0.34) and fertility costs (r = 0.46) (Table 3).

Increasing the number of feeding times in day: The real purpose of this strategy is to increase feeding distribution in day and continuous entrance of nutrition to rumen along with fixing rumen pH which may reduce any suffering from acidosis.

Although, 66% of cattlemen in this research believed that any applying of that method needs an increase in power and labor costs but considered it as an effective solution in prevention of acidosis and performed it accordingly. About 34% of cattlemen ignored the method for various reasons and did not perform it at all.

The obtained results of variance analysis show that applying of this managerial strategy has a significant effect on betterment of acidosis incidence rate, treatment costs, average production, gross income of milk sale (p<0.01) and fertility costs (p<0.05). But it has not a statistically significant effect on average fertility (p>0.05) (Table 1).

The mentioned results are in compliance with findings of Pitt and Pell (1997) who have stated that increase supplying of feeding may cause lower fluctuations of rumen pH. Shabi et al. (1999) stated that any increase in meal times may reduce any negative effect of serious fermentation of non structural carbohydrates. Also any increase in feeding time may increase dry matter intake, milk production efficiency as well. It was stated according to Shaver (2002) that feeding based upon once per day will reduce labor costs but since it will make cows to separate feeding for finding fresher and more palatable part of feed, this may threaten them to suffer from rumen acidosis. De Vries et al. (2005), concluded that any increase in number of feeding will cause harmonized distribution of feed through the day. This may cause a reduction in rumen pH changes and further reduction of rumen acidosis as well.

Ghorbani and Asadi Alamuti (2004) stated that any reduction in meal rate along with supplying enough feeding, are positive steps towards reducing of rumen acidosis incidence rate. The results obtained from average comparisons among studied groups show that there is statistically significant difference between acidosis incidence rate and treatment costs (p<0.05).

Although, there are some differences in studied variables such as average production, gross income, average fertility and fertility costs but it was not so much statistically significant (p>0.05) (Table 1).

The obtained results out of calculation the correlation coefficients for this variables show that applying of this strategy has a great relation with reduction of acidosis incidence rate (r = -0.90) and its treatment costs (r = -0.89). The correlation coefficient between current variable and production average was r = 0.47, gross income r = 0.44, average fertility r = 0.18 and fertility costs r = -0.30 (Table 3).

Applying of sodium bicarbonate for facilitating of rumen buffering circumstances: In this part we will study the effects of sodium bicarbonate as a buffering compound in complex with concentrate or in free choice form. In total 50 studied farms about 60% of them benefited from this managerial strategy and the remained 40% did not apply it no more.

The obtained results of variance analysis showed that any applying of this managerial strategy has a significant effect on acidosis incidence rate, treatment costs, average production, gross income, average fertility and fertility costs (p<0.01) (Table 1). Therefore, any applying of which may cause significant betterment of above mentioned variables.

These findings are in compliance with the results of Ghorbani and Asadi Alamuti (2004) who stated that benefiting from sodium bicarbonate make betterment in milk production and milk fat percentage. Furthermore the mentioned findings will approve the obtained results of Solorzano et al. (1989) who stated that benefiting from sodium bicarbonate will increase rumen PH, dry matter digestibility, crude protein and NDF. Ghorbani et al. (1989) reported that adding 1% of sodium bicarbonate to the shares of dairy cows will significantly increase the pH of rumen. Hu and Murphy (2005) evaluated the effect of adding sodium bicarbonate to the rations of dairy cows at early and mid lactation and concluded that it has no more effects in milk production but may increase milk fat percentage accompanied with an increase of 0.13 in rumen pH.

The obtained results out of comparing the average amount show that there is a statistically significant difference among studied groups from incidence rate variable and treatment costs (p<0.05). But there is not a significant difference among mentioned groups from 4 other variables including average production, gross income, average fertility and fertility costs (p>0.05). By calculation regression coefficients for evaluation any relation of this variable with other managerial and commercial indices it was revealed that sodium bicarbonate and incidence rate is r = -0.79. It is a sign of applying which for reducing treatment costs. The correlation coefficients for various variables including average production, gross income, average fertility and fertility costs respectively was equal to 0.56, 0.47, 0.31 and -0.44 as a sign of correlation rate of this variable with other indices (Table 3).

Effect of managerial strategies to acidosis prevention in transition period on production, economical and managerial parameters: This index is an average of performing considered managerial strategies for betterment of herds from acidosis viewpoint which is in fact a sign of applying these strategies in transition period.

Table 2:	The effect of applying rate and costs of effective managerial strategies on prevention from acidosis on economical and managerial variables
**Significant difference (p<0.01), *Significant difference (p<0.05), nsNon Significant differences (p>0.05)

Table 3:	Correlation coefficients among effective managerial strategies on prevention from acidosis and other managerial and economical indices

Upon performing multiple linear regression method for this variable and other indices and also variance analysis, it was revealed that percentage rate of effective managerial strategies had a positive and significant effect on acidosis incidence rate, treatment costs, average production, gross income, fertility costs (p<0.01) and average fertility (p<0.05). It is in a way that any increase in the level and implementation rate of these strategies may cause better conditions of these indices (Table 2).

According to the results of average comparison for different parameters among studied groups from view point of percentage of performing managerial strategies show that there was a statistically significant difference for acidosis incidence rate and treatment costs (p<0.05). In spite of some differences among these groups it was not significant for the average production, gross income, average fertility and fertility costs (p>0.05) (Table 2).

Also upon study the correlation coefficients among this variable and other related variables, it was revealed that correlation coefficients for implementation percentage of strategies and incidence rate was r = -0.97 and for treatment costs r = -0.92. It is a sign of further effects of increasing of applying level of effective managerial strategies on acidosis prevention and its result in reduction of treatment costs. Furthermore the calculated correlation coefficient for performing of managerial strategies and average production was r = 0.59, gross income r = 0.44, average fertility r = 0.30 and fertility costs r = -0.45 (Table 3).

The effect of applying costs of effective managerial strategies on prevention from acidosis on managerial and commercial parameters: The above mentioned parameter includes total costs for prevention from acidosis per head. This part is allocated to study any effects of which on managerial and economic parameters.

Upon performance of Multiple Linear Regression (MRL) and study of the results of analysis of variance, it was revealed that implementation costs of effective managerial strategies on acidosis prevention have a statistically significant effect on incidence rate and also treatment costs, average production, gross income, average fertility and fertility costs (p<0.01). It is in a way that any increase in applied costs for management of this metabolic disorders will make more betterment in mentioned parameters (Table 2).

The results of average comparisons show that there is a significant difference among various groups for applying costs of managerial strategies and incidence rate and treatment costs (p<0.01). On the other hand, it was not so much significant for other variables such as average production, gross income, average fertility and fertility costs (p>0.05) (Table 2).

Followings are the results of correlation coefficients on implementation costs and other indices:

Also followings are the results of general study of correlation coefficients for effective managerial strategies on prevention from acidosis: