The need for young cattle in amino acids
In growing calves for breeding flocks (heifer replacement) the goal is the next level of weight gain:
1-8 Life Week - 700-800 g / day;
9-12 Life Week - 750-900 g / day.
From 4 th to 7 th week of life comes the greatest consumption of whole milk substitute (milk).
animal lure prestarter for calves and high-quality hay to stimulate the development of the rumen function, which begins at the latest with the third week of life, significantly reduces the content of crude protein and essential amino acids in the overall diet. At the same time formed in the rumen microbial protein it takes an increasing share in covering the needs of animals in amino acids.
Smooth and individual transition from whole milk or milk replacer diet on ruminant makes it possible to use substitute milk of different quality and price category. The earlier the separation from WMS, the higher the requirements to the quality of the protein. In the first weeks of life of whole milk substitutes, which contain casein, is an advantage. On the 5 th week of life enough milk replacer, whose amino acid preferably derived from whey protein and soy. In general, whole milk replacers, which contain a fraction of skim milk powder, They should be supplemented with lysine and methionine in the synthetic form.
Fattening calves of average weight gain:
в 1-8 Time Life - 1200 г;
в 9-16 Time Life - 1400 г.
High weight gains are achieved by increasing the amount of permanent fed milk replacer and its concentration. In the second half of the watering period the products are often used with a high-fat and low-protein fraction and amino acids.
Table 1. Recommendations for amino acids calves (in milk replacer)
Cows need for amino acids
In contrast to the feeding of pigs and poultry, Cow calculations are still carried out on the crude protein or used in the duodenum crude protein (digestion of proteins, nXP). This is due mainly to the fact, that the process of digestion in ruminants characterized by a symbiosis between the host animal and a variety of microorganisms in the proventriculus, and so it is difficult to estimate the flow. This is partly due to the failed, What is known feed composition, the composition of microbial protein and protein composition of milk. The consequence of this is that, that in some countries, eg, in France and in the US, balancing rations for amino acids is a common practice.
essential amino acids.
Numerous scientific studies, the main limiting amino acids for dairy cows called lysine and methionine. The reasons for this are as follows:
- Microbial protein in its amino acid composition is best satisfies the need cow. Most of the protein from feed raw material contains less methionine and lysine in relation to the total content of essential amino acids, than microbial protein. Lysine different lower intestinal digestibility, other than a non-cleavable amino acids in the rumen of feed protein (UDP).
- The proportion of the total amount of lysine in the UDP essential amino acids is very often lower, than the same feed to rumen fermentation.
Methionine and lysine - is the essential amino acids in the microbial protein for cattle growing animals.
Methionine is particularly important for metabolism in the liver, regardless of cow productivity parameters, such as the milk yield or the milk protein content. One side, methionine used by veterinarians at such problems as the low consumption of feed or disturbances in fat metabolism. On the other hand, Through the addition of methionine can improve liver function.
Recommendations for cows amino acids
to ensure cows amino norms, compared with pigs and poultry, It is not so unambiguous. table 2 given amino acid requirements for cows, which are used in practice in France. Так, eg, cow with a live weight 650 kg and milk yield 30 kg (4% fat, 3,4% milk) in the small intestine is about the need for lysine 130 g and about the need for methionine 41 г.
Table 2. Cows need for amino acids
1)FCM: amount of milk based on 4% milk fat
2)PDI: digestibility in the small intestine protein
Stable amino acids in the rumen
Microbial protein has a high biological value due to its favorable amino acid composition. But still, especially for high yielding cows, formed in the microbial protein of methionine and lysine is insufficient for optimum performance cow. With the help of the methods available today drawing rations such deficit situation can be prevented. for example, by introducing into the diet in the rumen stable methionine and / or lysine is possible to meet requirements of animals in these amino acids. Due to this you can also increase the productivity of such indicators, the protein content in the milk produced or the amount of milk protein.
But the debate about the stable in the rumen amino acid is conducted not only in relation to the classic indicators of productivity. More importantly, that the addition of methionine can reduce the concentration of ketone bodies (beta-hydroxybutyrate and acetone). Stable rumen methionine can make an important contribution to reducing ketoznoy perspective in the first third of lactation in high yielding animals.
Also feeding sheep have reported a positive effect of methionine. The amino acid profile of the protein coat is characterized particularly high proportion of sulfur-containing amino acids. Therefore, a stable rumen methionine particularly positive effect on hair growth.
protein, coming from the feed, cleaved in ruminants primarily in proventriculus, and liberated in this process, ammonia is used as a bacteria source of nitrogen in protein synthesis. When providing nitrogen from feed protein or nonprotein nitrogen compounds exceeds the capacity of protein synthesis in bacteria proventriculus, excess ammonia is synthesized in the liver into urea. Therefore, excess protein leads to stress. Stable rumen amino acids can from this point of view the need to intentionally close the animals in the individual amino acids, without, To increase the ammonia concentration in the rumen.
protein metabolism in cows