Ag. Sinclair et al., PARTITIONING OF DIETARY-PROTEIN DURING LACTATION IN THE MEISHAN SYNTHETIC AND EUROPEAN WHITE BREEDS OF PIG, Animal Science, 62, 1996, pp. 355-362
Litter size of commercial European sow lines can be increased by the i
ntroduction of genes from the highly prolific, but obese Meishan. The
introduction of these genes into sow lines may necessitate different n
utritional strategies for lactation. A 2 x 2 x 2 factorial experiment
was used to investigate the influence of breed type (Meishan synthetic
50% (M) or purebred European Landrace and Large White (W)) and parity
(1 or 3) on response to dietary protein level (H=178g crude protein (
CP) per kg 8 g lysine per kg, L=136 g CP per kg 5 g lysine per kg over
a 5-week lactation. M were lighter and fatter at farrowing than W (P<
0.001), consumed more food (M=7.33 v. W=6.98 (s.e.d. 0.17) kg/day, P<0
.05) but had higher maternal weight loss (M=16.2 v. W=11.9 (s.e.d. 1.8
8) kg, P<0.05) and higher fat loss (M=6.5 v. W=2.6 (s.e.d. 0.77) mm P-
2 P<0.001) during lactation. Litter growth rate was higher for M than
for W (P<0.005) and for H than for L (P<0.005). Differences were found
between breeds in the partitioning of food protein. Overall, higher c
orrelations between lysine intake and litter growth rates were found i
n M (r=0.55, P<0.001) than in W (r=0.13, P>0.05). Lysine intake and so
w weight loss were more correlated in W (r=0.66, P<0.001) than in M (r
=0.15), P>0.05). Fat loss was correlated with initial fat depth in M (
r=0.61, P<0.001) but not in W. Weaning to conception intervals showed
a breed X diet interaction (log(e) days:ML=1.38, MH=1.55, WL=1.73, WH=
1.43, s.e.d. 0.14, P<0.05). It is concluded that M, with greater initi
al fat reserves, catabolize more body fat to support greater milk outp
ut. This is facilitated by provision of a high protein diet. The W sow
s do not utilize the extra protein for mild production but instead use
it to minimize weight loss (maintain protein status of their own body
) which may help prevent an extended weaning to conception interval.