Business Field

What are the characteristics of protein digestion?

 

The digestion of protein by cattle and sheep is mainly carried out in the rumen. The feed protein entering the rumen is decomposed into peptides under the action of rumen microorganisms and proteolytic enzymes, and further decomposed into amino acids. These peptides and amino acids are partially used by rumen microorganisms to synthesize bacterial proteins, and the other part can continue to be broken down into ammonia, carbon dioxide, and volatile fatty acids. Non-protein nitrogenous compounds in feed can also be decomposed into ammonia and carbon dioxide under the action of bacterial urease.

 

Ammonia in the rumen is metabolized through three metabolic pathways, one is that ammonia is used by bacteria to synthesize bacterial proteins, and then digested and absorbed in the true stomach and small intestine; The second is directly absorbed into the blood by the rumen wall, and urea is synthesized in the liver, part of which is excreted with urine, and the other part enters the salivary glands through the blood, and then enters the rumen in the form of saliva, so that the cycle is repeated, forming a nitrogen cycle in the rumen; The third is to enter the true stomach and small intestine after being absorbed into the blood, and to the liver to synthesize urea with urine excretion or participate in the nitrogen cycle.

Unused feed proteins and their degradation products in the rumen, as well as some newly synthesized bacterial proteins and endogenous proteins enter the true stomach and small intestine with chyme, and then are digested and absorbed, and the unabsorbed ones are excreted. The factors affecting the microbial protein synthesis of bovine rumen mainly include energy level, dietary nitrogen level, feeding level, energy source, different nitrogen sources, branched-chain fatty acids, minerals, silage, feeding frequency, ambient temperature, etc.

 

 

What is the energy needs of cattle and sheep with carbohydrate nutrition?

 

(1) The need for energy of beef cattle: Energy is necessary to maintain life activities or growth, reproduction, production, etc. China's current cattle and sheep feeding standards use the comprehensive net energy value, also known as the net energy system, that is, the comprehensive net energy = maintenance net energy + weight gain net energy unit is megajoules (MJ).

 

(2) Nutrition of carbohydrates: The composition of carbohydrates can be divided into two types: soluble and insoluble.

 

Insoluble carbohydrates refer to crude fiber substances, including cellulose, hemicellulose, and lignin. Cellulose is broken down to become glucose; After hydrolysis of hemicellulose, xylose, five-carbon sugar, etc. can be generated, because it is smaller than the molecule of cellulose, so it is easier to hydrolyze than cellulose.

 

Nutritional effect of carbohydrates: After carbohydrates are decomposed, low-grade fatty acids are generated, which are absorbed by the intestinal wall and participate in the tricarboxylic acid cycle in cattle and sheep to form high-energy phosphate compounds and generate heat energy. In addition to converting the carbohydrates ingested into glycogen for heat energy, the excess is converted into fat and stored as an energy substance in case of malnutrition, which is very important for fattening cattle and sheep.

 

Digestion and metabolism of carbohydrates by cattle and sheep carbohydrates are decomposed by microorganisms into lower fatty acids and carbon dioxide gas in the rumen, and the lower fatty acids are mainly acetic acid, propionic acid and butyric acid. Carbohydrates that are not digested in the rumen enter the true stomach and small intestine, and are affected by intestinal amylase and maltase in the small intestine, and part of the sugar and starch continue to be digested into glucose to be absorbed by the intestinal wall and enter the liver to synthesize glycogen.

 

The substances that are still not digested in the true stomach and small intestine enter the cecum and colon, where they are subjected to the action of bacteria to decompose cellulose and hemicellulose into lower fatty acids, which act the same as the rumen. Substances that are still not digested are excreted with the feces.

 

 

How do cattle and sheep digest and utilize the fat in feed?

 

(1) Digestion and metabolism of fat in the rumen After feed fat enters the rumen, three changes occur, namely, hydrolysis, hydrogenation of hydrolysates and synthesis of fatty acids. Rumen microorganisms can hydrolyze fat into fatty acids and glycerol (non-rumen fat can be caused by rumen acidosis by some rumen microorganisms). Fatty acids are saturated with microbial hydrogenation, and glycerol is further fermented and degraded to produce propionic acid. Rumen microorganisms can synthesize fatty acids of various structures.

 

(2) Digestion of fat in the small intestine: Although rumen microorganisms have a certain digestive effect on fat, the main role is the small intestine. Under the action of bile and pancreatic juice, fat is completely degraded and absorbed in the posterior part of the jejunum.

 

 

What role and efficacy of vitamins do cattle and sheep need?

 

(1) Vitamin A

The role of vitamin A is to maintain the health of mucosal epithelial tissue, and the normal function of mucosal epithelial tissue, maintain normal vision and reproductive function of cattle and sheep, so it is especially important for cows and sheep during pregnancy. If there is a lack of vitamin A, it is easy to lead to weakened resistance of the mucosal epithelial tissue of the whole body, causing a series of related diseases, more typically, the lack of vitamin A leads to the occurrence of pregnancy in cattle and sheep: abortion, stillbirth and other pregnancy diseases.

 

(2) Vitamin D

The main role of vitamin D is to regulate the absorption and utilization of calcium and phosphorus, and promote the growth and development of bones. Vitamin D deficiency can cause rickets in newborn calves and rickets in cows.

 

(3) Vitamin E

The main role of vitamin E is to resist the oxidation and improve the immune response of cells and body fluids, thereby improving the body's immunity. Usually, adult cattle can get enough vitamin E from their feed, and calves with vitamin E deficiency can cause muscular dystrophy. In addition, in long-term storage of feed, vitamins will continue to be lost with storage time, so we should not over-store feed, resulting in reduced nutrition of cattle feed.

 

(4) Water-soluble vitamin B

Water-soluble B vitamins include: thioflavin, riboflavin, pyridoxine, biotin, niacin, choline, etc., which have different effects on regulating physiological metabolism. The rumen of adult cattle and sheep can absorb nutrients in feed and synthesize some vitamin B, but the rumen of calves and lambs is underdeveloped, and can only be supplemented by drinking milk, if we artificially breastfeed calves, we must ensure that the milk temperature is within 40 degrees Celsius to prevent these vitamin B dissolving and disappearing.

 

The above are the four types of vitamins that cattle and sheep need: vitamin A, vitamin D, vitamin E, vitamin B function, and symptoms of deficiency.

 

 

What is the function of mineral nutrition for cattle and sheep?

 

The role of minerals is as follows:

1. Important components of animal body structure, about 5/6 are found in bones and teeth, mainly calcium, phosphorus and magnesium. The remaining 1/6 is found in tissues such as hair, hooves, horns, and muscles.

 

2. Participate in the composition of a variety of enzymes in the body, closely related to the metabolic process of sugar, fat and protein, and play an important role in the metabolic process in the animal, such as manganese, zinc, iron, iodine, cobalt is a component of certain enzymes, can also be the composition of hormones and vitamins and other active substances in the body.

 

3. Maintain the acid-base (pH) balance of the blood to maintain normal life activities.

 

4. Regulate blood, lymph and osmotic pressure to keep the osmotic pressure of body fluids constant, ensure that cells get nutrients, and maintain normal life activities of cells. The kidneys control the amount of minerals excreted in the urine through a change in osmolality.

 

5. In the process of metabolism of the body, affect the solubility of other substances in the body, such as hydrochloric acid in gastric juice can make the protein in the feed expand and denature, accelerate the hydrolysis of protein enzymes.

 

6. Minerals can also activate the activity of certain enzymes and enhance digestion.

 

7. It can maintain the excitability of nerves and muscles, such as sodium, potassium and hydroxide ions can make neuromuscular excitability. Calcium, magnesium and hydrogen ions reduce nerve and muscle excitement.

 

 

What are the nutritional characteristics of green feed?

 

(1) Crude protein

Crude protein content is rich, digestible, excellent quality, high biological value. The crude protein content generally accounts for 10%~20% of the dry matter, which is characterized by more content in leaves than straw, more leguminae than grasses, and high digestibility of crude protein. For example, the crude protein digestibility of alfalfa is as high as 76%, and the crude protein digestibility of wild grass and mountain grass is only 51%. The protein quality in green feed is better, the essential amino acids are more comprehensive, the content of lysine and histidine is more and the content of methionine is less, which has a good effect on the growth, reproduction and lactation of beef cattle. Because the amino acids contained in green feed are more comprehensive, the biological value of protein is higher, up to 80%, while the general seed feed is only 50%~60%.

 

(2) Rich in vitamins

Carotene content is one of the important factors that determine the nutritional value of feed. Green feed contains a large amount of carotene, 50~80 mg per kilogram, which is higher than other types of feed. The content of carotene and B vitamins in legume grass was higher than that in grass. Grass has a higher vitamin content than autumn grass. In addition, green feed is also rich in thiamine, riboflavin, niacin and other B vitamins, as well as more vitamin E, vitamin C and vitamin K.

 

(3) The content of calcium and phosphorus varies greatly

According to dry matter, the content of calcium in green feed is 0.2%~2.0%, phosphorus 0.2%~5%. Calcium and phosphorus in green feed are mostly concentrated in leaves, and their percentage of dry matter decreases with the maturity of plants.

 

(4) There is more nitrogen-free extractable

Less crude fiber. The crude fiber content of grass accounts for about 30% of dry matter, and the content of nitrogen-free extract accounts for 40%~50%. The digestibility of organic matter of high-quality forage is 75%~85%. Green feed has less crude fiber content and has the effect of stimulating the secretion of digestive glands in beef cattle, so it has good palatability and high digestibility, which can be regarded as health feed for beef cattle.

 

 

 

What are the nutritional characteristics of cereal feed?

 

Grain feed is one of the most important energy feed, the structure of cereal feed consists of seed coat, paste layer, endosperm and germ four parts, due to the different functions of the four tissues, the nutrients contained are also very different, the common main corn, wheat, sorghum, barley, oats, millet, rice, etc., the specific nutritional characteristics of the premix mixer are as follows:

 

(1) High content of nitrogen-free extract: usually accounts for 70% to 80% of dry matter, of which starch accounts for 80% to 90% of nitrogen-free extract, starch is the most valuable part of this type of feed, high digestibility for animals, so high net energy for fattening.

 

(2) Low crude fiber content: an average of 2% to 6%, so it is said that the digestion utilization rate of grain feed is high.

 

(3) Low protein content and poor quality: the average protein content is about 10%, which is difficult to meet the protein requirements of livestock and poultry. Poor protein quality, amino acid imbalance, lack of essential amino acids, especially lack of lysine, threonine, tryptophan, must be supplemented when preparing livestock and poultry diets.

 

(4) Imbalance in mineral content: calcium deficiency, general calcium content is less than 0.1%; high phosphorus content, general phosphorus content is 0.1% to 0.5%, but mainly phytate phosphorus, low utilization rate, and can interfere with the utilization of other mineral elements.

 

(5) Unbalanced vitamin content: Feed premix machinery found that most cereal feed is rich in vitamin B1, niacin and vitamin E, but lacks vitamin A, vitamin D, vitamin B2 and vitamin B12.

 

 

What are the nutritional characteristics of bran feed?

 

Bran feed contains more crude fat and crude protein, even B vitamins are rich, the disadvantage is that the proportion of calcium and phosphorus contained is extremely unbalanced, and most of the phosphorus exists in the form of phytic phosphorus, bran feed mainly refers to wheat bran, rice bran and so on.

 

Among them, wheat bran has a high crude protein content, up to 12%-17%, and the quality is relatively good, containing lysine content of 0.5%-0.6%, but the methionine content is very low, only about 0.1%, and the B vitamin content is also high. The energy value of bran is low, the calcium and phosphorus content is very unbalanced, calcium accounts for about 0.1%-0.2% in dry matter, phosphorus accounts for 1.0%-1.3%, almost 1:8 ratio. Most of the phosphorus exists in the form of phytate, and the utilization rate is low. Therefore, when using wheat bran as sheep feed, special attention is paid to supplementing calcium and phosphorus.

 

Rice bran, rice bran contains more fat and protein, of which the fat content is about 14%. The protein content is about 13%, in addition to being rich in vitamins such as thiamine and niacin. The content of unsaturated fatty acids in fat is also more, so it is easy to oxidize rancidity, which is not conducive to storage. The content of calcium and phosphorus in rice bran is also very different, up to a ratio of 1:22, and the same amount exists in the form of phytate, which is not conducive to being absorbed by sheep, so when feeding sheep with rice bran as sheep feed, you need to pay attention to supplementing phosphorus and calcium.

 

 

What should I pay attention to when feeding cake meal to cattle and sheep?

 

Cattle and sheep feeding cake meal mainly include soybean cake, rapeseed cake, flaxseed cake, cottonseed cake, peanut cake, sunflower cake, coconut cake, palm cake, sesame meal, castor seed meal, etc. However, this type of feed has a lot of resistant nutritional factors, so pay attention to the following problems when using.

 

First: Although the nutritional value of soybean cake is high, the digestion utilization rate is also high, feeding calves lambs and young cattle is very effective, but it should not be used more for fattening cattle and fattening sheep, because it can make the fat soft and affect the quality of meat.

Second: cottonseed cake contains cottonseed toxin, also known as gossypol, gossypol is very toxic, often chronic cumulative poisoning, its feeding generally only accounts for less than 7% of the diet. To reduce toxicity, it can be heated at 80-85°C for 6-8 hours, or fermented for 5-7 days, or add 100kg of ferrous sulfate per 1kg of cottonseed cake before feeding.

Third, rapeseed cake contains a erucic acid substance, which is subjected to the action of mustard hydrolase in the body, which will form isosulfates, which are toxic.

Fourth, flax kernel cake through the action of linxase, will cause cattle poisoning, but it can be detoxified after boiling water for ten minutes, and its feeding amount generally only accounts for less than 7% of the diet.

Fifth, peanut cake does not contain toxins, but the content of lysine and methionine is insufficient, and it is susceptible to aflatoxin, and its feeding amount generally accounts for less than 10% of the diet.

 

Urea as a protein supplement?

 

1. The amount of urea should not exceed 1/3 of the total nitrogen requirement, and not more than 1% of the dry matter of the diet.

2. Due to the good hygroscopicity of urea, it is easy to decompose into ammonia, can not be fed alone or dissolved in water, and can not drink water 2 hours after feeding.

3. Urea palatability is poor, add it to mixed concentrate feeding or with starch feed, salt and other mineral feed to make urea mineral feed licking bricks for cattle to lick and reduce the intake rate.

4. When feeding urea in feed, raw bean cake cannot be fed at the same time, because raw bean cake contains urease, which accelerates the decomposition of urea in the presence of water, causing losses.

5. The total amount of urea fed every day is fed multiple times, which is conducive to stabilizing the concentration of ammonia in the rumen and avoiding waste or poisoning. While urea is a good protein supplement that provides nitrogen to cattle, it does not provide other nutrients. Therefore, when supplementing protein with urea, it is necessary to supplement energy, minerals and vitamins at the same time. in order to get the desired effect.

 

 

 

What are the commonly used calcium feeds for cattle and sheep?

 

In cattle and sheep breeding, a nutritionally balanced diet is more important for the growth of cattle and sheep. Among the nutrients required by beef cattle, calcium and phosphorus are indispensable, while green feed often has insufficient calcium and phosphorus content, so calcium source feed needs to be supplemented. So what are the commonly used calcium source feeds?

 

1. Calcium carbonate. Calcium carbonate is white or off-white, odorless powder, commercially available pure calcium carbonate content should be more than 95%, calcium content above 38%. In general, its price is higher.

2. Shell powder. Shell powder is a product made from the shell of oysters, etc., which is crushed and is a gray-white or gray powder. Its chemical composition is also calcium carbonate. The calcium content of shell powder should reach 32%-34%, and the price is slightly higher than calcium carbonate. Good quality calcium carbonate powder and shell powder must contain about 38% calcium, and the magnesium content should not exceed 0.5%.

3. Dolomite. After crushing, natural dolomite can also be used as calcium feed. The chemical composition is calcium carbonate and magnesium carbonate compound salt, some magnesium content is 10%, calcium content is about 24%. Feeding efficiency is poor.

4. Plaster. The chemical formula of gypsum is an aqueous calcium sulfate, gray or white crystalline powder. There are two products. One is a crushed product of natural gypsum, and the other is a by-product of the phosphoric acid manufacturing industry. The latter often contains large amounts of fluorine and should be noted. The calcium content of gypsum is between 20% and 30%, which varies greatly.