Publication history: Accepted - 2 May 2020; Published online - 9 May 2020.Improved genetics in commercial
pig production have resulted in larger litter sizes.
However this has increased the prevalence of compromised
pigs exhibiting inferior birthweights,
weaning weights, and lifetime performance. This
study aimed to determine the effects of increased
sow lactation feed intake on growth of low and
average birthweight piglets until 10 wk of age. Low
(Low BW; <1 kg) and average (Av BW; 1.3–1.7 kg)
birthweight animals were reared in uniformly
weighted litters comprising 14 piglets on a foster
mother offered either a low (Low FA; max 7.5 kg/d)
or high (High FA; max 11 kg/d) feed allowance over
a 28- ± 1-d lactation. Piglet performance was monitored
from birth until 10 wk of age. Sows offered
a High FA consumed 42.4 kg more feed on average
than those offered Low FA, resulting in a greater
derived milk yield (P < 0.05). Animals of Av BW
remained heavier than Low BW pigs throughout
the trial (P < 0.05). Piglets reared by High FA sows
were heavier at weeks 3, 4, 5, and 7 (P < 0.05) but
not week 10 (P > 0.05). Growth rate of piglets relative
to their birthweight was significantly greater
for Low BW piglets than those of Av BW during
lactation (P < 0.001). Piglets reared by sows offered
a High FA expressed greater relative growth preweaning
(P < 0.05); however, postweaning relative
growth for piglets reared on sows offered a Low FA
was greater (P < 0.05) suggesting compensatory
growth. Neither birthweight nor sow feed allowance
significantly affected preweaning mortality (P
> 0.05). However, Low BW animals on sows with
a High FA recorded half the preweaning mortality
of Low BW pigs on sows with a Low FA. During
week 1 of lactation, Av BW litters recorded a
greater total suckling duration compared to Low
BW litters (P < 0.05) but there was no difference
in suckling frequency (P > 0.05). During week 3 of
lactation, High FA litters displayed a significantly
lower suckling frequency (P < 0.05) yet a greater
total suckling duration (P < 0.001). Average daily
gain was greater for Av BW pigs during weeks 4–7
(P < 0.001) but no difference was recorded between
weeks 7 and 10 (P > 0.05). Average daily feed intake
was greater for Av BW pigs throughout the nursery
period (P < 0.05) but feed–conversion ratio did not
differ compared to Low BW pens (P>0.05). In conclusion,
offering sows a High FA increased weaning
weight of all animals; however, birthweight was the
major determinant of postweaning performance
