Formulation and preparation method of pine sawdust-based food for rumiants

The waste products of the wood industries, particularly pine sawdust, represent a great potential source of dietary energy for ruminants. Even though the use of pine sawdust as part of a ruminant’s diet represents an important environmental impact, studies on this subject are scarce. It is worth mentioning that pine sawdust is currently being used as a source of fibre in ovine diet. However, its digestion is limited due to its high lignin content. The objective of the present investigation consists in the design of a new treatment process for lignin degradation into pine sawdust through the use of the fungus Pleurotus ostreatus. From the results obtained, a new and sustainable food for the ruminants based on degraded pine sawdust is proposed. The experiments carried out showed significant elevation in the exploitation of the nutritious components of pine sawdust contained in the developed product due to the improvements in the digestive parameters of the ruminants. With the results obtained, besides the nutritional and environmental impact, a better control of the costs generated by the feeding of the ruminants is intended. This is due to the fact that pine sawdust does not suffer from production variation in comparison with other consumables.


Intoduction
In Mexico, the increased usage of forages has caused the supply of these agricultural by-products to be insufficient.The constant growth of the cost of stubbles of maize, straws of wheat barley, oats, etc. is being observed, causing a considerable increase in its cost.It is worth mentioning that these forages are not available all the year and their production usually lowers on rainy seasons.On the other hand, a little more than 8 million cubic meters of wood are processed annually in Mexico [1].Sawdust is the main waste product in the wood industry, whose estimated production is 2.8 million cubic meters a year [2].The natural degradation of sawdust is very slow and it is a waste of low use nowadays.Its storage is creating serious pollution problems in the soils in which it is settled [3][4][5][6].Because it occupies a lot of space, sawdust causes considerable environmental problems.However, in the last years, the efforts to find alternatives for its utilization in order to obtain new high value products have increased.The incorporation of sawdust inside the nutrition of ruminants represents an economic and nutrimental advantage of its use [7].One of its advantages as a raw material is that the sawdust does not compete directly with the food destined for human consumption.In the systems of food production for ruminants, the forages can constitute from 5 to 40% of the total of the diet.Usually, the forages are added into the ruminants food to have the necessary fiber to support the functions of the rumen and to avoid disorders of the digestive tract.Nevertheless, to be able to use lignocellulosic materials contained in sawdust in food for ruminants, the degradation of the lignin contained within is important [8].The lignin, after the cellulose, is the principal component of wood.The importance of the degradation of the lignin is owed to the fact that this substance is completely indigestible for the ruminant bacteria and can cause an increase in the intestinal diseases, since its digestion requires the presence of oxygen [9][10][11].The excess of fiber reduces the capacity of food ingestion, the synthesis of ruminal microbial protein, the digestibility of the ration and the energy supply [12].Biological degradation of the lignin is very slow [13].According to the existing research, there are several ways in which a treatment can be given to a substratum of sawdust to modify its composition.However, according to N. Mosier et al. (2005), the pre-treatment of the lignocellulosic biomass in order to raise the performance is one of the most expensive steps [14].The objective of this research consisted in the design of a new treatment mechanism for lignin degradation into pine sawdust through a series of designed processes.The proposed development implied subjecting the sawdust to 4 different processes: physical, chemical, thermic and finally, a mixing process with the rest of the ingredients to reach the formulation of the final product.From the results obtained, a new and sustainable pine sawdust food for ruminants was proposed.

Processes
The development used in the present research implies subjecting the sawdust to 4 different processes:  the first one is a physical process (mashing) with the objective of minimizing the size of the particle to achieve a better size for digestive use  the second one is to reduce through a chemical process the percentage of lignin that the sawdust contains and to subsequently degrade the present cellulose in a sustainable manner. the third process refers to the thermic compression of the sawdust through the application of pressure and temperature to modify its properties. the fourth process is the interaction of the rest of the ingredients that will mix with the treated sawdust.
The particle size of the sawdust used in the present project was on average 2mm, with the purpose of increasing the contact area with the cellular and hemolytic microorganisms in the ruminants digestive tract.To obtain this particle size, a hammer mill with a screen size of 2 mm was used.Through the procurement of sawdust in 2 mm particle size, a chemical treatment using a solution of sodium hydroxide (NaOH) in a concentration range between 20-40% and a temperature between 80-90 °C during 45 minutes was used.The thermic process for lignin reduction was performed by heating up the sawdust in a microwave (MW).Nine different tests with 1 kg of sawdust each in which the temperature of the sawdust varied to achieve the desired properties was performed.The tests were performed so that the sawdust would reach a temperature of 40, 80 and 120 degrees through a heating process in the microwave with a power of 1100 W with an applied irradiation time of 70-80 seconds.The temperature that provided the best results was that off 80 °C.Under this processing, the lignin amount in the pine sawdust was reduced by 2-5%.Finally, the food for ruminants was formed adding the treated sawdust to wheat bran, soy, coconut flour, corn, oats, calcium supplement and salt with the proportions shown in Table 1.Posteriorly, 10 ruminants were fed with the food created for a period of 3 months.The analysis performed in the samples of food confirmed their nutritional value for a ruminant.The results from the Hematic Biometry Analysis performed on ovines are presented in Table 3.The results of improvements in the observed analysis are presented in Table 4.The sawdust treatment processes described above allowed to regulate in a better manner the ruminant conditions and therefore, propitiated a better exploitation of the food by the animal.Positive impact was generated and the digestive metabolism of the ovines was improved, which was reflected in the increase of consumption levels, weight increase and better food conversion.The interaction of the ingredients of the created formula propitiate digestion conditions with an increased microbial activity, especially due to the ruminant pH regulation and the energetic-proteic balance that the food consumption generates.This is reflected in an increased production of microbial protein, short length fatty acids (acetic, propionic and butyric) and primary metabolites (glucose, fatty acid and total protein), which were absorbed at the intestinal level.The serum concentrations of these metabolites and their proportions regulate the operation of certain organs and tissues.For the present investigation, the inclusion of pine sawdust in a diet formulated for ovines improved their hepatic physiology, which is evidenced through the measurement of diverse enzymes in the bloodstream of the observed ovines.An increase in the serum concentrations of these enzymes is positively correlated with a functional deterioration of the liver, this is to say that a reduction of these enzymes' concentrations in the blood serum indicated a better liver performance.In the same manner, the elaborated formula allowed to increase the levels of cholesterol in the blood serum, which can provoke a better energetic and protein use in the basal metabolism of the ovines.https://doi.org/10.1051/matecconf/201819203008ICEAST 2018

Conclusions
The sawdust comes from pine wood, which is produced and processed year-round, no matter the season.The results of the present project impact the wood industries directly, giving them an opportunity to re-invest their money.Likewise, the present project offers ranchers the possibility of obtaining a food product for their cattle which is of high quality and of fixed price for any time of the year.The present project has a major impact on the wood industries, allowing money to re-enter the market to be able to sell the sawdust with a good profit margin.The processed sawdust comes from pine trees, which are produced and processed year-round, no matter the season.This product has the advantage of being produced all the time, as opposed to ruminant nourishments derived from other products, which can depend on the season and the availability of the product.The solution this project offers for the reuse of pine sawdust waste is the multiple possibility to obtain nourishment at any time of the year.The degradation of lignin from sawdust through the design presented in this research, generates a new form of nourishment for ruminants, which has the advantage of improving its digestibility.Furthermore, sawdust can be combined with different sources of protein and minerals to help generating the highest levels of microbial degradation in ruminants that is possible.This form of nourishment allows the increase of digestive parameters as well as liver performance, which translates into a higher biological efficiency and productivity of the animal.The invention presented in this research is currently under request for a patent.

Table 1 :
Food formulation for sheep using pine sawdust.

Table 2 .Table 2 .
Physicochemical formulation for sheep utilizing the nourishment with pine sawdust.

Table 4
Improvements that the sheep had by being fed with the created formulation