Determining amino acid levels
The amount of amino acids consumed by pigs greatly influences growth rates, feed efficiency and the overall productivity of the hog operation.
Lysine is the most important amino acid, and while it is present in Manitoba feed, it appears in the lowest quantity relative to the pigs’ requirements.
Determining the optimum level of lysine intake for your pigs depends on a number of factors: age, lean growth rate and sex.
The rate of muscle deposition decreases with increasing liveweight and age. This, along with increased feed intake, means as pigs mature, they require less amino acid.
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In addition to simply being wasted, a high lysine diet fed during the finishing phase will actually result in decreased performance. This is likely because of the metabolic costs associated with eliminating excess amino acids from the body.
Altering dietary lysine levels to match the pig’s growth curve can improve performance and lower production costs.
Dietary requirements
Growing-finishing pigs with high-lean deposition rates require more amino acids in their diets because of great protein (muscle) synthesis, a slightly higher maintenance requirement for some amino acids and a lower daily feed intake. The dietary amino acid needs of high-lean growth-rate pigs (over 340 g/day) can be up to 30 percent higher than for medium growth-rate pigs.
Determining the lean deposition rate is one of the main difficulties in applying lysine estimates to farm situations. However, if a producer is using livestock from a commercial supplier, the company should know the expected lean deposition rate.
The other option is to challenge feed. That is, feed more protein than is needed to a representative group of pigs through to slaughter and then estimate the maximum lean deposition rate from carcass data.
Gilts require a higher concentration of amino acids than barrows because of their lower feed intake and increased leanness.
Sex and amino acids
The impact of sex on amino acid requirements is highly dependent on the pigs’ weight. Rates of lean tissue growth are similar between barrows and gilts at light weights (20 to 30 kg), but gilts gain more lean tissue than barrows as they mature.
Consequently, differences in daily lysine requirements increase as gilts and barrows approach maturity. These differences have resulted in the practice of “split-sex feeding,” where gilts and barrows are penned separately and fed different diets. Research shows that split-sex feeding can reduce production costs by as much as $1/cwt.
After the lysine requirement has been determined, the remaining amino acid levels fall in place under the concept of “ideal protein.” Ideal protein matches the amino acid balance in the feed to the amino acid balance in the meat.
A problem facing hog producers when formulating rations is determining how much their pigs are consuming. Accurate feed intake data is essential.
For example, if growing pigs require 20 g of lysine per day, this corresponds to a dietary concentration of 0.8 percent if pigs are eating 2.5 kg/day. If eating only 2.0 kg/day, the necessary dietary level is one percent lysine.
– Animal Nutrition Update
