Effective fiber is the fraction of fiber that stimulates the animal to chew the feed and is related to factors such as the size of the forage pieces.
Effective fiber (peNDF) significantly affects the ruminal activity of livestock. peNDF is the fraction of fiber that stimulates animal chewing and is related to factors such as forage portion size. Along with the increase in the amount of fiber and especially the effective fiber in animal feed, the amount of saliva secretion and the ratio of acetic acid to propionic acid and the amount of milk fat and the stability of rumen pH increase. When using rations with optimal portion sizes and appropriate amounts of NDF in feeding ruminants, the amount of feed consumption and its digestibility increases and in general positively affects livestock performance. According to the recommendations of the National Research Council (NRC), fiber should account for 25% of the dry matter of animal feed, and at least 75% of that fiber should be provided through forage. The Pennsylvania sieve can be used to evaluate the size distribution of forage particles and also to calculate the amount of effective fiber in the diet. Until now, due to the lack of optimal standards and appropriate methods for determining the properties of effective fiber, no specific recommendations have been provided in this field.
An introduction to the importance of effective fiber in ruminant nutrition
Fiber is very important in feeding ruminants. Maintaining animal health and optimal rumen function and creating optimal physiological conditions are among the duties of fiber. Fiber can be defined as the indigestible part or part of the feed with low digestibility and completely inaccessible, which occupies a lot of space in the animal’s digestive system. From a nutritional point of view, fiber has physical and chemical properties that are related to factors such as mechanical processes of digestion (chewing feed and passing) and enzymatic decomposition during the fermentation process. The amount of fiber in the diet is expressed by ADF and NDF indices. ADF includes cellulose and lignin, and its amount is strongly related to factors such as feed digestibility, while it has little relationship with the amount of feed consumed by livestock. NDF includes cellulose, hemicellulose and lignin in animal feed and is more related to feed volume and chewing process than ADF and crude fiber.
In general, ruminants require effective fiber, which significantly affects the process of chewing feed and ruminal activities in livestock. Effective fiber stimulates the animal to chew the feed. Along with increasing the amount of fiber and especially effective fiber in the diet, the amount of saliva secretion and the ratio of acetic acid to propionic acid increases. The use of rations with optimal portion sizes and appropriate amounts of NDF leads to an increase in animal feed consumption and its digestibility, and this positively affects animal performance. In order to evaluate the effect of effective fiber in feeding ruminants, it is necessary to pay attention to parameters such as the process of chewing food, pH of the rumen, the amount of animal feed consumed, and the percentage of milk fat. By using effective fiber, information can be obtained on the chemical properties of NDF and feed components. Therefore, this parameter is considered as an efficient measure to evaluate rumen performance
The size of the pieces of fodder
Improving the size of fodder pieces can be considered as one of the important nutritional strategies in dairy cows. Small feed particles pass through the rumen quickly and cause less stimulation of the animal to chew the feed and its performance. In other words, the results of the studies indicate that the appropriate size of the feed pieces increases ruminal digestion due to the increase in the availability of effective microbial enzymes for fiber breakdown. Research results show that in high-producing cows, reducing the average size of forage pieces increases the amount of feed consumption and nutrient supply. Therefore, the size of feed pieces should be taken into consideration as one of the important issues in animal nutrition, but determining the right size for fodder pieces in practice is difficult and difficult.
Influence on the process of chewing and rumination
The process of chewing food should be considered as one of the factors affecting the amount of saliva production and secretion. The type of fodder, the ratio of fodder to concentrate, the amount of fodder consumption and the physiological state of the animal are among the factors affecting this process. The amount of fiber and the ratio of fodder to concentrate affects the density of the ration and digestibility, the amount of digestion, the duration of rumination, the total duration of chewing the feed, and the rate of passage of digested materials through the rumen. Effective fiber stimulates the animal to chew the feed, increases the process of chewing the feed by the animal and thus leads to an increase in the secretion of saliva, which acts as a buffering agent and is effective in maintaining the pH of the rumen and the ratio of acetic acid to propionic acid and The amount of fat in milk works. It should be mentioned that along with the reduction of particle size, the chewing process of feed is reduced per kilogram of NDF.
The information from table (1) indicates that due to the use of rations containing ground fodder or fodder with small particles, the process of chewing food in livestock is 20 to 60% lower than when using fodder with Long particles are reduced. There is a defining relationship between the length of fodder particles and the process of chewing feed, and using it, it has been proven that the animal’s chewing activity when it eats fodder particles with a length of 40, 20, 5 and 1 mm will be 80, 70, 50 and 25, respectively. Was.
Forage particle size affects the feeding behavior of livestock. The presence of a stable environment in the rumen leads to the favorable growth of the microbial population in it, which is caused by the uniformity of the supply of nutrients. The results of the research indicate that there is the highest correlation between the amount of food remaining on the 19 mm tray and the process of chewing the feed and the feeding behavior of the animal. The relationship between feed particle size and chewing process is not completely linear. Ruminants tend to consume diets containing long, coarse particles containing high amounts of fiber, which greatly affect rumen fermentation. For this important practical reason, the effect of particle size or physical effective fiber on activity and feeding behavior of livestock is essential.
Effect on rumen pH
The pH of the rumen should be considered as a very important factor because it significantly affects the growth process of the rumen microbial population. The growth of rumen microbial population affects the production rate of rumen microbial fermentation products and their physiological function. The consumption of fermentable carbohydrates and the rate of production, absorption and consumption of volatile fatty acids are among the factors affecting rumen pH. The suitability of rumen pH varies depending on different activities. For example, starch is digested at a pH of 5.8 to 6.4, but bacteria effective in breaking down fiber work at a pH of 6.2 to 6.8. To meet the needs of all nutritional measures, rumen pH should be maintained in the range of 5.8 to 6.4. The use of rations containing optimal amounts of effective fiber leads to stability in rumen pH and maintaining it in the range of 5.8 to 6.4. Rumen pH can be used as an indicator to evaluate rumen health and optimal performance.
Diets containing higher fermentable carbohydrate or non-fibrous carbohydrate (NFC) lead to higher organic acid production and peNDF on the other hand lead to higher chewing activity and salivation. Balanced diets that have adequate NFC and peNDF levels are better achieved when preparing TMR diets than feeding forage and concentrate alone.
Effect on the consumption of animal feed
The size of the feed particles and the number of times the feed is consumed are factors that affect the amount of animal feed consumed. These two factors are influenced by particles and ratio of concentrate to forage. In high-producing cows, the amount of feed consumption increases in order to maintain the amount of milk production and profitability. The ease of hydrolysis of NDF leads to its rapid passage through the rumen and increasing optional feed consumption in livestock.
In high-yielding dairy cows, the effect of the size of ration pieces and effective fiber on the amount of animal feed consumption have often been discussed to a great extent, which increase the amount of animal feed consumption due to the positive effect on the amount of rumen filling.
After combining the results of various studies, the researchers concluded that the effect of the size of the ration pieces on the amount of feed consumption depends on the type of fodder source and the ratio of fodder to concentrate and the type of concentrate, which significantly affects the process of rumen decomposition. They say that changes in rumen decomposition are a reflection of the influence of effective factors on the condition of the rumen and the digestive process.
Effect on milk fat content
Effective fiber plays an important role in maintaining the microbial population and increasing the efficiency of ruminal fermentation. The use of rations containing large amounts of effective fiber positively affects the amount of milk production and feed efficiency. The amount of milk fat production is directly related to the amount of rumen fermentation products and its performance. Milk fat can be used as an indicator to evaluate the health of the rumen and evaluate the desirability of the amount of fiber in the diet. According to the results of using the Pennsylvania sieve, the diet of Holstein cows in early to mid-lactation in order to maintain the amount of milk fat in high-producing cows, to such things as the amount of fiber consumption in the diet and the process of chewing feed and saliva secretion and rumen fermentation it is related. The use of diets containing large amounts of fiber leads to an increase in the process of chewing feed and saliva secretion, and creates a favorable environment for the growth of microbes effective in the decomposition of cellulose and the production of acetic acid. Acetic acid is considered a necessary precursor for milk fat, therefore increasing the ratio of acetic acid to propionic acid in rumen fluids leads to more milk fat production.
Identifying the physical characteristics of the ration is one of the essential things to improve the rumen fermentation performance. Ruminants need roughage. This type of fiber significantly affects the process of chewing feed and rumen activities. Effective fiber is a part of the diet that stimulates the animal to chew the feed and leads to the secretion of saliva and the production of a buffer and increasing the pH of the rumen. peNDF is an index that can be used to evaluate the amount of effective fiber in the diet. Different methods can be used to measure the peNDF in the diet, each of which has a different application and validity point of view. Are. The amount of effective fiber in each food item can be calculated using the amount of NDF and the physical effectiveness factor. The Pennsylvania sieve is a common tool that can be used to express the size distribution of feed particles and calculate the amount of effective fiber in the diet. Until now, due to the lack of a standard and a valid method to identify and evaluate the physical properties of fiber in the diet, no specific recommendations have been provided. Properly reducing the size of forage pieces may reduce the amount of effective fiber in the diet, but on the other hand, it increases the amount of feed consumption and its digestibility, as well as the amount of volatile fatty acids in the rumen. Reducing the incidence of feed separation behaviors by livestock and increasing the amount of fiber consumption. There is a great relationship between the size of the ration pieces and the process of chewing the feed, which itself affects the pH of the rumen. When feeding animals with diets containing optimal amounts of NDF, other factors such as the amount of fermentable carbohydrates become more important. and should be paid attention to.