Agriculture Reference
In-Depth Information
(2005) proposed that it is possible that a thin lactating sow which is gaining weight and
putting on backfat will be more productive than a fatter sow which is losing weight or
backfat.
In the past 5 to 10 years, a growing opinion suggests that a specific minimum body fat
content at first breeding is not needed to ensure lifetime reproductive success. Sørensen
(2006) showed data of a commercial Danish study where feeding a diet containing 15%
less amino acids and 20% more energy from 100 to 140 kg body weight resulted in backfat
thicknesses greater than if fed a typical lactation diet for the same period. However,
the increased fatness did not affect the subsequent reproduction performance or
longevity of gilts. It was believed that gilts fed the less energy-dense diet were sufficiently
fat. The animals used in that study therefore did not need the fat enhancing regimen.
Gill (2007) also presented data indicating no relationship between gilt backfat depth
at first mating and lifetime productivity (Figure 1.2). In his study gilts were fed a low
protein diet to restrict lean gain and increase fat deposition during development. The
regimen successfully increased backfat depth at first service; but was not associated with
the number of piglets born in the female's lifetime. On the other hand, backfat depth
was associated with a reduced parity one weaning to conception interval and a smaller
number of sows culled for reproductive failure prior to the completion of parity two. This
suggests that fatness may still have some importance for longevity. Differences in backfat
thicknesses lasted until weaning at parity two.
Not all new research supports a viewpoint that fat is not important. Some contend
that there is increased risk of poorer reproduction and stayability with gilts that start
reproduction with too little or too much body fat. Indeed, Bussières (2013) reported a
clear linear relationship between backfat depth at first service and lifetime total born
(Figure 1.3). A first service target of 15 to 16 mm is recommended by this author. It is
100
Total alive
80
60
40
20
0
0
5
10
15
20
25
30
35
Backfat thickness at
rst service (P2, mm)
Figure 1.2. Relationship between backfat thickness at first service and total number born alive in the sow's
lifetime (taken from Gill, 2007).
