The attitude of our customers remains positive. It’s a nice thing to hear that these farms are making good use of forwarding contracting in both hogs and feed supplements.

Energy density of the diet

With modern lean-type pigs, one of the biggest limiting factors in pig growth under practical conditions is reduced energy intake, especially for pigs up to 65 kg. As the energy density of the diet increases, there is an increase in protein growth up to the level of the genetic potential of the pigs. With good genotypes, this may occur at about 85 kg. After this weight, daily lean growth remains the same up to slaughter weight (113 kg). However, the response in fat growth to increased dietary energy level remains linear.

Although an increase in the energy level of the diet usually results in a decrease in feed intake, energy intake usually increases. The formulation or nutrient specifications of your diets should be farm- specific, that is, the diets should be formulated on the basis of knowledge of the lean tissue growth rate and feed intake of the pigs on your farm. Without such knowledge, estimates of nutrient requirements must be made. An example of such estimated requirements is shown in Table 1.

Table 1. Nutrition allowance for growing-finishing pigs

Weight, kg	20-40	40-60	60-80	80-100	100-115
Feed intake/day, kg	1.3	1.85	2.40	2.90	3.30
Gain/day, kg	0.70	0.85	0.92	1.00	0.95
DE, Mcal/kg	3.47	3.45	3.25	3.25	3.25
% Protein	21	19	17	15	14
% Lysine	1.30	1.15	1.00	0.85	0.70
% Calcium	0.8	0.70	0.65	0.60	0.60
% Phosphorus	0.60	0.55	0.55	0.50	0.50

Table 2. Ideal pattern of amino acids as a percent of the lysine level

Amino Acid	Digestible amino acid basis
Pig weight, kg	20-50	50-75	75-120
Lysine	100	100	100
Threonine	61	63	63
Tryptophan	17	18	18
Methione + Cystine	57	58	59

These suggested nutrient allowances should be appropriate for pigs of above-average growth rate. Although they won’t promote excessive fatness, they should allow carcass backfat levels between 18-24 mm, which should facilitate easy removal of skin from the carcass by pulling in skinning slaughter plants.

For hogs sold to packers that do not skin the carcass (scalding plants), the dietary energy level could be reduced to 3.15 Mcal DE/kg in the growth period 80 to 115 kg.

Because pigs can adjust their feed intake according to the energy content of the diet, it is essential that the amino acid lysine be fed in a specific ratio to the energy in the diet, at least up to the late finishing stage. A suggested lysine to energy ratio for pigs with good lean growth rate might be:

Pig weight, kg	Grams digestible lysine/Mcal DE
20-40	2.4
40-80	2.1
80-100	1.8
100-120	1.6

There are other dietary essential amino acids that must be included in the diet if the pig is to grow well. These essential amino acids are included in the diet in a specific ratio to lysine, reflecting the approximate ratios that they occur in pig muscles. An example of such a ratio is shown in Table 2. This ratio of amino acids is called an ideal ratio. Only those amino acids likely to be limiting in Western Canada are included in the table.

The final step

By careful selection of feedstuffs on the basis of cost and quality, diets can be formulated to meet the pig’s nutrient requirements and thereby promote optimum and cost effective lean tissue growth.