Agriculture Reference
In-Depth Information
Effective ME requirements for milk production can be estimated with reasonable accuracy
from average daily gain of the litter (ADGl) and litter size (LS; NRC, 2012):
Effective ME requirement for milk production (kcal/d) = 7.03 × ADGl (g) - 129 × LS
In practical terms, when using corn and soybean meal-based diets with an effective ME
content of 3,300 kcal/kg, a lactating sow with a body weight of 200 kg will require 1.6 kg
feed/d for maintenance and 1.7 kg feed per kilogram of litter growth rate.
In modern highly productive sows, energy intake generally is not sufficient to support
energy requirements for body maintenance functions and milk production. As a
consequence, these sows will mobilize energy from both body protein and body lipid
stores, which can impact long-term sow reproductive performance as discussed earlier.
Therefore, management of lactating sows should be aimed at maximizing energy intake,
which is discussed later in this chapter.
6.3.3
Energy sources
Dietary energy encompasses the energy produced from oxidation of proteins, lipids and
carbohydrates after digestion and absorption. Oxidation of glucose derived from starch,
the main form of carbohydrates in cereal grains and pulses, represents the major source of
dietary energy for the sow. Common grains in sow diets include yellow dent corn, barley,
oats, sorghum and wheat, with levels of inclusion varying depending on grain availability
and prices, and stage of production. Grains contain relatively low concentrations of crude
protein (8.3% in corn up to 14% in hard red wheat) and are often limiting in lysine or
threonine; in contrast, their starch concentration is high, varying between 39% in oats to
as high as 70% in sorghum. The energy and starch composition of these grains is presented
in Table 6.1. Of the grains presented, corn and sorghum have the highest energy content,
in part because of their relatively high content of fats and starch. For the nursing sow,
it is common to add additional sources of energy in the form of vegetable oil or animal
fat to improve palatability and increase the energy density of the diet. Energy generated
from the oxidation of fatty acids derived from dietary lipids is over two-fold that of starch
(Table 6.1). Supplemental oil or fat at an inclusion rate of 2 to 7% is acceptable depending
on the ingredient composition of the diet and environmental temperature. Schoenherr
et
al.
(1989) reported improved litter gain in sows fed diets containing 10.6% supplemental
choice white grease when exposed to a thermal stress of 32 °C. Higher inclusion levels
of fats, however, may decrease flow through feeders. High quality distillers dried grains
with solubles (DDGS) produced by the ethanol industry and containing over 27% crude
protein, 33% neutral detergent fibers and over 6% fat, may be used as a source of energy,
fiber and protein in gestating and lactating sow diets. While the peer-reviewed literature
is limited, it is recommended that the maximum inclusion levels of high quality DDGS
be up to 40% in gestation diets and up to 30% in lactation diets (Hill
et al.
2008; Stein,
2007; Stein and Shurson, 2009).
