Dairy cattle forage provides the nutrients and effective fiber needed by the cow to increase the digestibility of the whole diet because the rumen of ruminants is designed to eat forage and the quality of dairy cattle fodder is based on achieving high production, health, useful performance and efficiency. Above is a herd of dairy cows. Composition, digestibility and physical form of forage limit cattle performance.
Dairy cattle forage is a good quality feed that provides the necessary nutrients and effective fiber to the cow without forcing people to change the recipe of the feed ration.
The quality of the ration determines how much of it you can use in the ration and how much food material is required to be added to the ration, but the quality of dairy cattle fodder cannot be defined alone and must be based on the content of the ration. and judged how much it can help the performance of the cow.
First step: measuring the amount of fodder for dairy cows
The first thing to do in relation to the composition and digestibility of fodder is to accurately measure their amounts. Take the sample from the food that the cow eats. Otherwise, analysis of compounds and digestibility will not be useful.
Soluble fiber in neutral detergent is a part of forage whose physical form stimulates rumination and its digestion rate is much lower than other parts of fiber. Measurement of fiber digestibility (NDFD) provides a tool that determines the potential of forage fiber to meet the nutritional needs of cattle. This volume measurement helps the farmer to evaluate these things: 1- To what extent the microbes can perform the fermentation process to produce nutrients for the cow. 2- How much fodder can a cow eat without filling its rumen with slow-digesting fiber. The higher the NDFD, the lower the forage quality. The amount of NDFD is estimated in several steps, and because it is fermented by rumen microbes, it is more variable than the estimate of crude protein, which has only one complete chemical measure in the feed. On average, in the conducted experiments, it was shown that the evaluated values of 30 hourly NDFD of animal feed samples are in the range of ±4.9% of the average (consider an NDFD sample with an average of 50%, the range of these values in the laboratory is between will be 45 to 55 percent). Values can vary in each laboratory, variations in fermentation rates are due to differences between samples in the initial hours of fermentation.
Another part of forages is non-forage carbohydrates (NFC), which are estimated to be 98% digestible. This digestibility is mainly due to water soluble carbohydrates (sugar, oligosaccharides, fructans) but not necessarily due to starch. Starch digestion is affected by the amount of feed grinding, fermentation and protein matrix structure.
Forage digestibility and performance of dairy cattle
The main list of needs of dairy cows:
• Digestible feed materials that provide the nutritional needs of dairy cows.
• Effective fiber that has a structure that maintains rumen function and protects the rumen against rumen acidosis.
• Some parts of animal feed that are not digestible and can pass through the rumen and reach the small intestine for further digestion.
In addition, due to the physical limitation of the rumen in terms of filling, it is necessary to provide fodder that prevents consumption reduction, while providing enough fiber to maintain rumen function and cow health.
The NRC software in 2001 attempted to provide recommendations for NDF, forage NDF, and non-fibrous carbohydrate (NFC). The amount of dairy cattle fodder and fiber required to maintain good production in the herd also varies according to the type of feed (NFC).
The higher the forage’s NDF, the more NFC or starch can be added. If conditions are such that the cow eats too much grain in its rations, separates feed, swallows feed, suffers from heat stress, or consumes sources of starch with very high fermentation rates (high moisture corn husks, barley or fine milled wheat), is considered a high-risk management issue to add more NDF and less NFC to avoid digestive problems.
Good quality fodder provides nutrients and effective fiber needed by cows to increase the digestibility of the whole animal feed, while poor quality dairy fodder has the opposite effect.
NRC recommendations when adjusting the amount of NDF of dairy cattle forage and its digestibility:
• Fodder NDF should constitute 75% of total NDF.
• Forage NDF should be adjusted to 0.8 to 1% of cow’s body weight.
• If the goal is to adjust the NDFD of the total ration to provide nutrients, it is necessary to balance the digestibility of the forage, the amount of forage NDFD that can be fed to the cow without distorting intake, and the amount of non-forage NDF that can be supplemented. A balance must be made to provide digestible NDF and maintain acceptable starch intake to the fed cow.
The amount of NDF included in the forage is an indicator to ensure that the cow is receiving enough physically effective fiber to maintain effective rumen function and rumination to create a balance between starch fermentation and other NFCs. If the fiber is fermented (rapidly and to a large extent) or reduced in size, it passes through and does not remain in the rumen long enough to be effective, and conversely, if the fiber is fermented slowly, it can remain in the rumen for a long time. remain and be effective.
Corn silage is an edible forage that shows the effect of digestibility on fiber effectiveness. Feeding corn silage does not increase total gastrointestinal fiber digestibility as much as laboratory NDFD evaluations suggest, but does increase dry matter intake and rumen emptying of NDF. The explanation that can be given for these results is that corn or silage corn with higher digestibility is broken down and passes through the rumen faster before being completely fermented.
When rations are adjusted to meet nutritional requirements based on forage composition and digestibility, there is no absolute way to determine in advance whether the forage’s NDF composition and digestibility will exceed effective fiber. provides sufficient or insufficient. It is necessary to consider cows, cows are the only source for accurate assessment of the amount of effective fiber in the diet, rumination of at least 50% of the cows indicates the adequacy of effective fiber in the diet, if they are sleeping, drinking or in heat. not be Among these cows, only 5% of these cows’ stools may not be abnormal and not like other cows (they seem to show no signs of disease or separation of feed) and somehow a small number of loose or long fiber stools. (longer than 2.5 centimeters(.
The digestibility of starch increases with the increase in the time that the corn grain remains in the silo, so the analysis of the degradability of the silated corn starch should be done over time due to the change. The problem with ration adjustment is that starch digestibility in silage or corn or high moisture is a variable target.
Starch fermentability may increase dramatically when corn with a suitable moisture content (32-35%) is kept in silage throughout the winter.
It may be necessary to limit the use of highly fermentable starches in the diet to avoid reduced digestibility. This may be problematic when the starch content of silage corn is high (more than 30% of dry matter) and silage corn constitutes the majority of forage in the diet of dairy cows.
Good quality dairy cattle fodder:
It was talked about feeding high quality fodder, but what should be focused on is the proper quality of fodder. A good quality dairy forage is a feed that provides enough nutrients and effective fiber for the cow without tempting people to defy the ration recipe.
Forages with high or low NDFD can be problematic. As NDF increases, the digestibility of fiber decreases somewhat. There are usually limits on the amount of such forage eaten without reducing the absorption and consumption of digestible nutrients. The percentage of starch should not be more than 25-28%.
Fermentable fiber sources such as soybean hulls can be added to digestible foods without overly restricting starch intake. Eating too much starch does not necessarily meet the cow’s energy needs and can cause the herd to suffer from digestive disorders until performance, digestibility, feed efficiency and income are reduced.
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