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18 August 2016
Pork News & Views
be more accurate. Adding by-products high
in fiber to the mix will affect the DE and ME
values to some extent due to energy and heat
present through internal interactions, making
NE a more reliable value. In addition, studies
suggest that by using NE values, feed cost and
nitrogen excretion can be reduced.
Fats/Lipids/Oils
Fats such as oils and lipids are added to
manage energy levels of the diet and vary in
digestibility depending on chain length and
saturation. Saturated fats are made of single
carbon bonds only. The digestibility is af-
fected by the ratio of unsaturated to saturated
fatty acids and declines as the ratio falls below
1.6 to 1. In addition, as the length of the
chain increases, the digestibility decreases.
Price and digestibility are the main factors
affecting the determination for ingredients to
be used as a fat source. Fats are highly palat-
able and can be added during extreme heat
to provide energy while producing little addi-
tional body heat due to digestion. The type of
fat can affect the quality of the carcass; feed-
ing high amounts of saturated fats produces
high saturated fats in the pigs’ body fat and
is regularly added to finishing diets for that
purpose. Fats added to diets can improve
palatability and is also a means to control dust
in feed, while acting as a lubricant during the
manufacturing of feeds, especially pelleting.
However, fats added in excess quantities can
decrease pellet quality, impact animal perfor-
mance and feed efficiency. Fats have more
impact on the latter during hot summers
than during colder seasons. This is important
because if feed intake goes down, the con-
centration of other nutrients required need
to be increased to meet the pigs’ demands.
The ratio between calories and amino acids
consumed must be kept consistent.
For example:
A swine diet consists of 3400kcal/kg DE with
0.85% lysine. A pig eats 1.6kgs/day of this
diet, consumes 5440kcal and 13.6g of lysine
a day. Heat stress sets in and we increase the
energy content of the diet to 3600kcal/kg DE.
Assuming the pig still eats the 5440 kcal a day
as it adjusts to meet energy requirements, the
pig will now eat 1.51kgs/day and was unable
to maintain its lysine intake which decreased
to 12.8g/day. Therefore, for this particular
diet the lysine concentration will need to be
increased to 0.9%.
Carbohydrates
Carbohydrates play an important role in
providing energy to the animal and are made
up of chains of sugars linked together and
are named according to the number of single
sugars bonds: monosaccharides, disaccha-
rides, and polysaccharides. Similar to protein
digestion, enzymes are needed to break down
the carbohydrates to make them available.
However, monogastrics lack the enzymes to
break down complex sugars found in legumes
as well as those found in soybeans. For this
reason enzymes are often added to the diet.
Starch/Sugar/Fiber
As said before, simple sugars and starches are
used as a source of energy for pigs. Simple
sugars such as glucose and lactose are great
for energy sources for young pigs, but caution
is advised when feeding fructose and sucrose
as it may cause diarrhea. Due to its costs, sug-
ars are most often used in neonates. Starches
are the main energy source, but are not well
digested by pigs until they are 3 weeks old.
Fiber is another energy component and is
referred to as acid detergent fiber (ADF) and
neutral detergent fiber (NDF) and is deter-
mined by laboratory testing. Although some
nutritionists see these components more
applicable to determining a ration for rumi-
nants, it gives an indication of the digestibility
and energy available. ADF to refers to the
cell wall portion and is made up of lignin and
cellulose. The value is important as it relates
to the ability of an animal to digest where
a higher ADF suggests a decrease in digest-
ibility. NDF refers to the cell wall fraction that
includes lignin, cellulose and hemicellulose.
Looking at both the ADF and NDF, nutrition-
ists are able to determine the digestibility and
energy available to the animal.
Minerals
Minerals are added when the basal diet pro-
vides insufficient quantities. Minerals are cat-
egorized between macro minerals (calcium,
phosphorous, sodium, chloride, potassium,
magnesium) and micro minerals (iron, zinc,
copper, manganese, iodine, and selenium).
Macro minerals such as calcium, phospho-
rous, sodium, and chloride make up the
majority of the required minerals. Phospho-
rous (P) levels, however, create a concern for
the environment and ingredients are evalu-
ated to have a high P digestibility to avoid
over feeding and match the animals’ needs.
Additional phytase is added to aid its diges-
tion, as P is involved in essential metabolic
processes. Calcium plays an important role in
bone mineralization and is usually expressed
as a ratio to total P- typically at a ratio of 1.0 to
1.5, or as a ratio to available P of 2.1 to 3.1.
Vitamins
Vitamins are essential in generating chemi-
cal reactions needed for metabolism and
almost all are made up of carbon, oxygen
and hydrogen. Vitamins are needed in much
smaller amounts than any other ingredient,
yet there can be adverse effects when animals
are deficient. There are two types of vitamins,
water soluble and fat soluble. Water soluble
vitamins cannot be stored in the pigs’ body,
and excess is excreted mainly in urine. Water
soluble vitamins include vitamin C, thiamin,
riboflavin, niacin, vitamin B6 and B12, folate,
biotin, choline, and phanthothenic acid. Vita-
mins A, D, E and K are considered fat soluble
and are important for the animal to function
and maintain health. Vitamins A and E may be
added to the diet separately or incorporated
into the minerals as a supplement. This gives
the feed manufacturer flexibility in prepar-
ing diets based on the stage of life the diet
is being manufactured for. Due to their low
inclusion rate, these are a small price for the
benefits vitamins provide.
Water
In addition to the nutritional analysis of feed,
water testing should also be done regularly.
Water is often the forgotten nutrient yet is so
important. Remember that water makes up
70% of the live weight and body water turn-
over is higher in young and highly productive
animals, especially during lactation. Table
1 shows the water intake of sows, farrow to
finish, (Pork Production Reference Guide
2000, Prairie Swine Centre Inc). Water quality
must be tested routinely and be free of high
concentrations of adverse minerals, sulphates,
bacteria contamination, and chemical con-
tamination.
Remember that nutrient recommendations
are guidelines containing a safety margin to
account for the variation found in ingredients
used. Laboratory analyses of ingredients help
to create a cost effective and balanced diet
while meeting the animals’ requirements.
In addition, good quality water should be
provided, as it is required in greater quantity
than any other nutrient.